超级军网郁闷 摆渡不到
来源：百度文库 编辑：超级军网 时间：2024/05/02 17:38:10
怎么让木材在几个小时内快速吸水？摆渡怎么也查不到 [:a10:]怎么让木材在几个小时内快速吸水？摆渡怎么也查不到 [:a10:]
烧成木炭
你没有这样的设备。在庭院花架上和地基上的的木材，那种青色的木材就是一种用压力把防蛀防腐化学剂注入木纤维中而形成的特种木料。靠正常吸收，除非这种树木长得飞快，特别松软。
日本有一种化学药水可以让木材硬度大三到四倍 目前正在实用化实验 这个的应用价值极大 被评为十大什么的发明 我现在找不到了 老兄有看过报道吗？
PS：本人想要的是普通木材能在几个小时内快速吸水的方法 增加木材的水分含量:handshake
PS：本人想要的是普通木材能在几个小时内快速吸水的方法 增加木材的水分含量:handshake
:L 怎么大家的问题越来越专业了哦
把它泡在水里，煮啊煮啊煮啊煮啊煮啊煮啊煮啊煮啊煮啊煮啊煮
一天几十上百吨 怎么煮？ :L
快搜一下，这里有一个专利讲的是木材加硬技术。
http://www.freepatentsonline.com/y2006/0134342.html
木材快速吸水只能靠压力，另外是加大截面积，但这样就破坏了木材的结构。
http://www.freepatentsonline.com/y2006/0134342.html
木材快速吸水只能靠压力，另外是加大截面积，但这样就破坏了木材的结构。
有没有什么药剂加入水中可以加快木材吸水能力？ 还有那个网站不行啊
Title:
Methods for increasing breaking strength in wood products
Document Type and Number:
United States Patent 20060134342
Kind Code:
A1
Abstract:
The invention provides a method for increasing strength in wood that comprises contacting with the wood to be treated with a copolymer of silicone units having the general formula: (MaDbTcQd)x where M is R3SiO1/2—; D is R2SiO—; T is RSiO3/2—; Q is Si(O1/2)4—; R is a generalized organic radical selected from: linear or branched hydrocarbon radicals of 1-8 carbons containing 0-1 degree of unsaturation, or phenyl, or trifluoropropyl radicals; a, b, c, d are real numbers and further provided the ratio of a/(c+d) is between 0 and 4; the ratio of b to the rest is not subject to limitation provided the final base viscosity is between 50-3500 cSt; and at least one R group of each molecule must be a hydrolysable group; and maintaining the contact for a time sufficient to establish a change in the chemical structure of the wood which is reflected in an increase in at least one measurable parameter reflecting an increase in the strength of the wood over an untreated wood from the same lot.
Inventor:
Glassel, David (Spring, TX, US), Gary Ernest (Grapevine, TX, US)
Application Number:
11/016636
Publication Date:
06/22/2006
Filing Date:
12/17/2004
View Patent Images:
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Referenced by:
View patents that cite this patent
Export Citation:
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Primary Class:
427/325
Other Classes:
427/440, 427/397
International Classes:
B05D3/00; B05D1/18
Attorney, Agent or Firm:
Martin, Mcgregor L. (26415 Oak Ridge Drive, Spring, TX, 77380, US)
Claims:
We claim:
1. A method for increasing strength in wood that comprises contacting with the wood to be treated with a copolymer of silicone units having the general formula: (MaDbTcQd)x where M is R3SiO1/2—; D is R2SiO—; T is RSiO3/2—; Q is Si(O1/2)4—; R is a generalized organic radical selected from: linear or branched hydrocarbon radicals of 1-8 carbons containing 0-1 degree of unsaturation, or phenyl, or trifluoropropyl radicals; a, b, c, d are real numbers and further provided the ratio of a/(c+d) is between 0 and 4; the ratio of b to the rest is not subject to limitation provided the final base viscosity is between 50-3500 cSt; and at least one R group of each molecule must be a hydrolysable group; and maintaining the contact for a time sufficient to establish a change in the wood which is reflected in an increase in at least one measurable parameter reflecting an increase in the strength of the wood over an untreated wood from the same lot.
2. The method of claim 1 that further comprises mixing a cross-linking agent with the copolymer that comprises a siloxane polymer of the general formula: (MaDbTcQd)x formula to which the following parameters apply: the ratio of a/(c+d) is between 0 and 4; the ratio of b to the rest is not subject to limitation provided the final cross-linking agent viscosity is below 350 cSt; and R is a generalized organic radical selected from: linear or branched hydrocarbon radicals of 1-8 carbons containing 0-1 degree of unsaturation, or phenyl, or trifluoropropyl radicals and at least one R group of each molecule must be a hydrolysable group.
3. The method of claim 1 that further comprises providing a crosslinking catalyst mixed with the copolymer.
4. The method of claim 3 wherein the catalyst is a tetraalkyl titanate or tetraalkyl zirconate.
5. The method of claim 1 comprising diluting the copolymer with an aliphatic solvent composed primarily of C7-C16 paraffinic, cycloparaffinic and isoparaffinic hydrocarbons containing less than about 0.5% aromatic hydrocarbons.
6. The method of claim 5 comprising wherein the aliphatic solvent is composed primarily of C9-C14, paraffinic, cycloparaffinic and isoparaffinic hydrocarbons.
7. The method of claim 5 comprising wherein the aliphatic solvent is composed primarily of C10-C10, cycloparaffinic and isoparaffinic hydrocarbons.
8. The method of claim 5 comprising the aliphatic solvent Conosol 145.
9. The method of claim 5 wherein a natural product oil selected from the group consisting of almond bitter oil, anise oil, basil oil, bay oil, caraway oil, cardamom oil, cedar oil, celery oil, chamomile oil, cinnamon oil, citronella oil, clove oil, coriander oil, cumin oil, dill oil, eucalyptus oil, fennel oil, ginger oil, grapefruit oil, lemon oil, lime oil, mint oil, parsley oil, peppermint oil, pepper oil, rose oil, spearmint oil (menthol), sweet orange oil, thyme oil, turmeric oil, oil of wintergreen, juniper oil, tall oil, pine oil; a synthetic natural product oil mimic that comprises at least one synthetically produced or isolated chemical identified as a component of a natural product oil elected from the group consisting of almond bitter oil, anise oil, basil oil, bay oil, caraway oil, cardamom oil, cedar oil, celery oil, chamomile oil, cinnamon oil, citronella oil, clove oil, coriander oil, cumin oil, dill oil, eucalyptus oil, fennel oil, ginger oil, grapefruit oil, lemon oil, lime oil, mint oil, parsley oil, peppermint oil, pepper oil, rose oil, spearmint oil (menthol), sweet orange oil, thyme oil, turmeric oil, oil of wintergreen, juniper oil, tall oil, pine oil.
10. The method of claim 9 wherein the oil is from the group consisting of cedar oil, cinnamon oil, citronella oil, clove oil, eucalyptus oil, juniper oil, tall oil, and pine oil.
11. The method of claim 1 wherein the oil is cedar oil.
12. The method of claim 1 wherein R groups may be the same or different and each is a lower alkyl group of no more that four carbons.
13. The method of claim 1 that wherein all non-terminal copolymer R groups are methyl.
14. The method of claim 2 that comprises a crosslinker having wherein an R group in an alkoxy group is an alkyl group comprising from 1 to 4 carbon atoms.
15. The method of claim 14 that further comprises methyl groups at each non-alkoxy position.
16. An article of manufacture comprising wood processed according to claim 1.
17. An article of manufacture comprising wood processed according to claim 5.
18. An article of manufacture comprising wood processed according to claim 8.
19. An article of manufacture comprising wood processed according to claim 9.
20. An article of manufacture comprising wood processed according to claim 11.
Description:
TECHNICAL FIELD
This invention provides methods for increasing the strength of wood. The invention also provides novel break resistant wooden articles of manufacture.
BACKGROUND OF THE INVENTION
As supplies of old growth timber are depleted world wide, increased emphasis on new rapid growing sources of wood has developed. One major concern with new growth wood, especially certain rapid growth hybrids is the lack of strength in the new growth woods compared to the strength of old growth woods. Numerous agents have been reported to increase the strength of treated wood, for example, U.S. Pat. No. 6,686,056 teaches improved strength in wood imparted by drying oils. A trade secret material of unknown composition was marketed in the United States from shortly after the First World War until the late 1950s under the trade names Vaccinol or Seasonal. This product claimed to increase the strength of treated wood.
Among the various agents that can impart strength to wood are materials that impregnate the wood and crosslink its internal structural elements to increase the cohesion of the wood fibers to each other. These materials include polymer forming reagents such as siloxanes, silanes and methylsilioxanes.
In the prior art these materials have been applied to various aspects of wood treatment including dimensional stabilization and moisture control. One approach focuses on surface coatings such as paints stains, varnishes and sealants. These methods treat the surface of the material to be protected but do not fully penetrate the wood. Whenever the coating is broken or flawed the protective effect is decreased. Since the protection is localized on the surface, it is subject to weathering and as the coating is broken down, for example by mechanical abrasion or ultraviolet radiation damage, the protection is gradually lost. Typical examples of this group are U.S. Pat. Nos. 5,413,867; 5,354,832; 5,085,695; 4,913,972, and references cited therein. These patents teach the use of organosilanes and organosilicates for the preparation of coating materials, but do not focus on the goal of the present invention, modification of the internal structure of the wood to exclude moisture.
Modification of wood by treatment with siloxanes is disclosed in U.S. Pat. No. 5,652,026 and references cited therein. This approach focuses on altering wood to increase its fire resistance and only incidentally mention the additional benefits of increased dimensional stability derived from excluding water from the cellulose fiber structure. The methylsiloxanes disclosed require the presence of a boron or phosphorus function, while the references cited therein focused on formation of inorganic complexes with metal alkoxides within the wood cells. None of the references recognized that changing the surface activity of cellulose or lignocellulose structures with simple carbon substituted siloxanes would produce the beneficial results sought while avoiding the use of potentially toxic materials such as the metal salts, phosphorus and boron compounds.
Another use of siloxane reagents to modify wood or cellulose materials is found in U.S. Pat. Nos. 5,204,186 and 5,120,581. These patents teach a very broad group of compounds useful as fire retardants. These patents also note the additional benefits derived by moisture reduction in the treated materials. The silioxane materials disclosed require either at least a group in each molecule that contains a halogen, or a group having a silicon bond that requires less than 72 kcal/mole to break. Neither of these requirements is present in the compounds of the present invention.
U.S. Pat. No. 6,303,234 involves a process of imparting fire retardant properties to a cellulosic material comprising coating a cellulosic material with sodium silicate by contacting a sodium silicate solution with the material to be coated, dehydrating the coating, and depositing a coating of a silicon oxide glassy film on the sodium silicate coated material. In one embodiment, the coating of silicon oxide is a monomolecular layer of silicon monoxide. The “water glass” or liquid sodium silicate is a salt of silicic acid, and while it may include polysilicates is quite different from the siloxane polymers of the present invention.
No art was found that teaches altering the internal structures of wood to increase the strength of the wood by contacting the wood with a siloxane polymer optionally diluted with a hydrocarbon solvent carrier, and optionally a naturally occurring oil. A method and composition to practice the novel treatment are described below, and produce novel articles of manufacture are set out below.
SUMMARY OF THE INVENTION
The invention provides a method for increasing strength in wood that comprises contacting with the wood to be treated with a copolymer of silicone units having the general formula: (M a D b T c Q d ) x where M is R 3 SiO 1/2 —; D is R 2 SiO—; T is RSiO 3/2 —; Q is Si(O 1/2 ) 4 —; R is a generalized organic radical selected from: linear or branched hydrocarbon radicals of 1-8 carbons containing 0-1 degree of unsaturation, or phenyl, or trifluoropropyl radicals; a, b, c, d are real numbers and further provided the ratio of a/(c+d) is between 0 and 4; the ratio of b to the rest is not subject to limitation provided the final base viscosity is between 50-3500 cSt; and at least one R group of each molecule must be a hydrolysable group; and maintaining the contact for a time sufficient to establish a change in the wood which is reflected in an increase in at least one measurable parameter reflecting an increase in the strength of the wood over an untreated wood from the same lot. Preferably the method further comprises mixing a cross-linking agent with the copolymer that comprises a siloxane polymer of the general formula: (M a D b T c Q d ) x meeting the following parameters apply: the ratio of a/(c+d) is between 0 and 4; the ratio of b to the rest is not subject to limitation provided the final cross-linking agent viscosity is below 350 cSt; and R is a generalized organic radical selected from: linear or branched hydrocarbon radicals of 1-8 carbons containing 0-1 degree of unsaturation, or phenyl, or trifluoropropyl radicals and at least one R group of each molecule must be a hydrolysable. It is also preferred to provide a crosslinking catalyst mixed with the copolymer. Any crosslinking catalyst known in the art may be used however preferred catalysts are tetraalkyl titanates or tetraalkyl zirconates where the alkyl groups may be the same or different. This mode of treatment provides a surface treatment and in some woods permeation of the wood is possible with some undiluted polymers; however, it is generally preferred to dilute the polymer with a solvent. While an aqueous solvent or even high pressure steam might be used, hydrocarbon solvents are preferred.
Because the viscosity of the copolymer may decrease or prevent penetration to the interior of the wood, it is desirable to dilute the copolymer with a hydrocarbon solvent. Use of a hydrocarbon solvent also decreases the rate of undesirable side reactions such as gel formation. Although any hydrocarbon solvent that carries the copolymer into cellulose fiber structures, such as wood, may be used the preferred solvents are aliphatic solvents composed primarily of C 7 -C 16 paraffinic, cycloparaffinic and isoparaffinic hydrocarbons containing less than about 0.5% aromatic hydrocarbons. More preferably, the aliphatic solvent is composed primarily of C 9 -C 14 , paraffinic, cycloparaffinic and isoparaffinic hydrocarbons and of those range of C 10 -C 13 is preferred. The current most preferred solvent is Conosol 145 marketed by Penreco, Inc, of Houston, Tex. Optionally additional benefits maybe obtained by adding to the treatment mixture a natural product oil selected from the group consisting of almond bitter oil, anise oil, basil oil, bay oil, caraway oil, cardamom oil, cedar oil, celery oil, chamomile oil, cinnamon oil, citronella oil, clove oil, coriander oil, cumin oil, dill oil, eucalyptus oil, fennel oil, ginger oil, grapefruit oil, lemon oil, lime oil, mint oil, parsley oil, peppermint oil, pepper oil, rose oil, spearmint oil (menthol), sweet orange oil, thyme oil, turmeric oil, oil of wintergreen, juniper oil, tall oil, pine oil; a synthetic natural product oil mimic that comprises at least one synthetically produced or isolated chemical identified as a component of a natural product oil elected from the group consisting of almond bitter oil, anise oil, basil oil, bay oil, caraway oil, cardamom oil, cedar oil, celery oil, chamomile oil, cinnamon oil, citronella oil, clove oil, coriander oil, cumin oil, dill oil, eucalyptus oil, fennel oil, ginger oil, grapefruit oil, lemon oil, lime oil, mint oil, parsley oil, peppermint oil, pepper oil, rose oil, spearmint oil (menthol), sweet orange oil, thyme oil, turmeric oil, oil of wintergreen, juniper oil, tall oil, pine oil. Preferred oils are cedar oil, cinnamon oil, citronella oil, clove oil, eucalyptus oil, juniper oil, tall oil, and pine oil. The most preferred oil is cedar oil.
In the copolymer the R groups may be the same or different and each is a lower alkyl group preferably of no more that four carbons. Especially preferred are those copolymers wherein all non-terminal copolymer R groups are methyl. In the preferred cross-linking agent each has an R group in an alkoxy group that is an alkyl group comprising from 1 to 4 carbon atoms. Especially preferred cross-linking agents further comprise methyl groups at each non-alkoxy position.
The invention also provides novel articles of manufacture comprising wood processed according to the various embodiments summarized above. Treatment according to the methods of the invention generates polymers within the structural matrix of the wood which increase the strength of the wood by increased cohesion of the wood fibers to each other.
DETAILED DESCRIPTION OF THE INVENTION
General Description of the Invention
In order to understand the invention at its most basic level it is importation to understand the basic properties of wood. According to a standard text, “Construction: Principles, Materials, and Methods” by Simmons, H. Leslie.; Olin, Harold Bennett, New York, N.Y., John Wiley & Sons, Inc. (US), 2001, Chapter 6 page 366 et seq., {Cited below as Simmons et al.} (Captions deleted from quotation. “ . . . ” indicates deletions other than captions and [ ] indicates insertions or change in case), “ . . . [w]ood cells, or fibers, are primarily cellulose cemented together with lignin. The wood structure is about 70% cellulose, between 12% and 28% lignin, and up to 1% ash-forming materials. These constituents give wood its hygroscopic properties, its susceptibility to decay, and its strength. The bond between individual fibers is so strong that when tested in tension they commonly tear apart rather than separate. The rest of wood, although not part of its structure, consists of extractives that give different species distinctive characteristics such as color, odor, and natural resistance to decay.
It is possible to dissolve the lignin in wood chips using chemicals, thus freeing the cellulose fibers. By further processing, these fibers can then be turned into a pulp from which paper and paperboard products are made. It is also possible to chemically convert cellulose so that it may be used to make textiles (such as rayon), plastics, and other products that depend on cellulose derivatives.”
Just as it is possible to dissolve the lignin in wood chips and release the wood fibers it is also possible to add to the cohesion of the wood fibers by adding polymeric materials to the internal structure of the wood and strengthens the wood as a result. The treatment of the present invention results in increased strength for new growth lumber, making it a useful replacement of old growth materials.
(Continue)
Methods for increasing breaking strength in wood products
Document Type and Number:
United States Patent 20060134342
Kind Code:
A1
Abstract:
The invention provides a method for increasing strength in wood that comprises contacting with the wood to be treated with a copolymer of silicone units having the general formula: (MaDbTcQd)x where M is R3SiO1/2—; D is R2SiO—; T is RSiO3/2—; Q is Si(O1/2)4—; R is a generalized organic radical selected from: linear or branched hydrocarbon radicals of 1-8 carbons containing 0-1 degree of unsaturation, or phenyl, or trifluoropropyl radicals; a, b, c, d are real numbers and further provided the ratio of a/(c+d) is between 0 and 4; the ratio of b to the rest is not subject to limitation provided the final base viscosity is between 50-3500 cSt; and at least one R group of each molecule must be a hydrolysable group; and maintaining the contact for a time sufficient to establish a change in the chemical structure of the wood which is reflected in an increase in at least one measurable parameter reflecting an increase in the strength of the wood over an untreated wood from the same lot.
Inventor:
Glassel, David (Spring, TX, US), Gary Ernest (Grapevine, TX, US)
Application Number:
11/016636
Publication Date:
06/22/2006
Filing Date:
12/17/2004
View Patent Images:
Images are available in PDF form when logged in. To view PDFs, Login or Create Account (Free!)
Referenced by:
View patents that cite this patent
Export Citation:
Click for automatic bibliography generation
Primary Class:
427/325
Other Classes:
427/440, 427/397
International Classes:
B05D3/00; B05D1/18
Attorney, Agent or Firm:
Martin, Mcgregor L. (26415 Oak Ridge Drive, Spring, TX, 77380, US)
Claims:
We claim:
1. A method for increasing strength in wood that comprises contacting with the wood to be treated with a copolymer of silicone units having the general formula: (MaDbTcQd)x where M is R3SiO1/2—; D is R2SiO—; T is RSiO3/2—; Q is Si(O1/2)4—; R is a generalized organic radical selected from: linear or branched hydrocarbon radicals of 1-8 carbons containing 0-1 degree of unsaturation, or phenyl, or trifluoropropyl radicals; a, b, c, d are real numbers and further provided the ratio of a/(c+d) is between 0 and 4; the ratio of b to the rest is not subject to limitation provided the final base viscosity is between 50-3500 cSt; and at least one R group of each molecule must be a hydrolysable group; and maintaining the contact for a time sufficient to establish a change in the wood which is reflected in an increase in at least one measurable parameter reflecting an increase in the strength of the wood over an untreated wood from the same lot.
2. The method of claim 1 that further comprises mixing a cross-linking agent with the copolymer that comprises a siloxane polymer of the general formula: (MaDbTcQd)x formula to which the following parameters apply: the ratio of a/(c+d) is between 0 and 4; the ratio of b to the rest is not subject to limitation provided the final cross-linking agent viscosity is below 350 cSt; and R is a generalized organic radical selected from: linear or branched hydrocarbon radicals of 1-8 carbons containing 0-1 degree of unsaturation, or phenyl, or trifluoropropyl radicals and at least one R group of each molecule must be a hydrolysable group.
3. The method of claim 1 that further comprises providing a crosslinking catalyst mixed with the copolymer.
4. The method of claim 3 wherein the catalyst is a tetraalkyl titanate or tetraalkyl zirconate.
5. The method of claim 1 comprising diluting the copolymer with an aliphatic solvent composed primarily of C7-C16 paraffinic, cycloparaffinic and isoparaffinic hydrocarbons containing less than about 0.5% aromatic hydrocarbons.
6. The method of claim 5 comprising wherein the aliphatic solvent is composed primarily of C9-C14, paraffinic, cycloparaffinic and isoparaffinic hydrocarbons.
7. The method of claim 5 comprising wherein the aliphatic solvent is composed primarily of C10-C10, cycloparaffinic and isoparaffinic hydrocarbons.
8. The method of claim 5 comprising the aliphatic solvent Conosol 145.
9. The method of claim 5 wherein a natural product oil selected from the group consisting of almond bitter oil, anise oil, basil oil, bay oil, caraway oil, cardamom oil, cedar oil, celery oil, chamomile oil, cinnamon oil, citronella oil, clove oil, coriander oil, cumin oil, dill oil, eucalyptus oil, fennel oil, ginger oil, grapefruit oil, lemon oil, lime oil, mint oil, parsley oil, peppermint oil, pepper oil, rose oil, spearmint oil (menthol), sweet orange oil, thyme oil, turmeric oil, oil of wintergreen, juniper oil, tall oil, pine oil; a synthetic natural product oil mimic that comprises at least one synthetically produced or isolated chemical identified as a component of a natural product oil elected from the group consisting of almond bitter oil, anise oil, basil oil, bay oil, caraway oil, cardamom oil, cedar oil, celery oil, chamomile oil, cinnamon oil, citronella oil, clove oil, coriander oil, cumin oil, dill oil, eucalyptus oil, fennel oil, ginger oil, grapefruit oil, lemon oil, lime oil, mint oil, parsley oil, peppermint oil, pepper oil, rose oil, spearmint oil (menthol), sweet orange oil, thyme oil, turmeric oil, oil of wintergreen, juniper oil, tall oil, pine oil.
10. The method of claim 9 wherein the oil is from the group consisting of cedar oil, cinnamon oil, citronella oil, clove oil, eucalyptus oil, juniper oil, tall oil, and pine oil.
11. The method of claim 1 wherein the oil is cedar oil.
12. The method of claim 1 wherein R groups may be the same or different and each is a lower alkyl group of no more that four carbons.
13. The method of claim 1 that wherein all non-terminal copolymer R groups are methyl.
14. The method of claim 2 that comprises a crosslinker having wherein an R group in an alkoxy group is an alkyl group comprising from 1 to 4 carbon atoms.
15. The method of claim 14 that further comprises methyl groups at each non-alkoxy position.
16. An article of manufacture comprising wood processed according to claim 1.
17. An article of manufacture comprising wood processed according to claim 5.
18. An article of manufacture comprising wood processed according to claim 8.
19. An article of manufacture comprising wood processed according to claim 9.
20. An article of manufacture comprising wood processed according to claim 11.
Description:
TECHNICAL FIELD
This invention provides methods for increasing the strength of wood. The invention also provides novel break resistant wooden articles of manufacture.
BACKGROUND OF THE INVENTION
As supplies of old growth timber are depleted world wide, increased emphasis on new rapid growing sources of wood has developed. One major concern with new growth wood, especially certain rapid growth hybrids is the lack of strength in the new growth woods compared to the strength of old growth woods. Numerous agents have been reported to increase the strength of treated wood, for example, U.S. Pat. No. 6,686,056 teaches improved strength in wood imparted by drying oils. A trade secret material of unknown composition was marketed in the United States from shortly after the First World War until the late 1950s under the trade names Vaccinol or Seasonal. This product claimed to increase the strength of treated wood.
Among the various agents that can impart strength to wood are materials that impregnate the wood and crosslink its internal structural elements to increase the cohesion of the wood fibers to each other. These materials include polymer forming reagents such as siloxanes, silanes and methylsilioxanes.
In the prior art these materials have been applied to various aspects of wood treatment including dimensional stabilization and moisture control. One approach focuses on surface coatings such as paints stains, varnishes and sealants. These methods treat the surface of the material to be protected but do not fully penetrate the wood. Whenever the coating is broken or flawed the protective effect is decreased. Since the protection is localized on the surface, it is subject to weathering and as the coating is broken down, for example by mechanical abrasion or ultraviolet radiation damage, the protection is gradually lost. Typical examples of this group are U.S. Pat. Nos. 5,413,867; 5,354,832; 5,085,695; 4,913,972, and references cited therein. These patents teach the use of organosilanes and organosilicates for the preparation of coating materials, but do not focus on the goal of the present invention, modification of the internal structure of the wood to exclude moisture.
Modification of wood by treatment with siloxanes is disclosed in U.S. Pat. No. 5,652,026 and references cited therein. This approach focuses on altering wood to increase its fire resistance and only incidentally mention the additional benefits of increased dimensional stability derived from excluding water from the cellulose fiber structure. The methylsiloxanes disclosed require the presence of a boron or phosphorus function, while the references cited therein focused on formation of inorganic complexes with metal alkoxides within the wood cells. None of the references recognized that changing the surface activity of cellulose or lignocellulose structures with simple carbon substituted siloxanes would produce the beneficial results sought while avoiding the use of potentially toxic materials such as the metal salts, phosphorus and boron compounds.
Another use of siloxane reagents to modify wood or cellulose materials is found in U.S. Pat. Nos. 5,204,186 and 5,120,581. These patents teach a very broad group of compounds useful as fire retardants. These patents also note the additional benefits derived by moisture reduction in the treated materials. The silioxane materials disclosed require either at least a group in each molecule that contains a halogen, or a group having a silicon bond that requires less than 72 kcal/mole to break. Neither of these requirements is present in the compounds of the present invention.
U.S. Pat. No. 6,303,234 involves a process of imparting fire retardant properties to a cellulosic material comprising coating a cellulosic material with sodium silicate by contacting a sodium silicate solution with the material to be coated, dehydrating the coating, and depositing a coating of a silicon oxide glassy film on the sodium silicate coated material. In one embodiment, the coating of silicon oxide is a monomolecular layer of silicon monoxide. The “water glass” or liquid sodium silicate is a salt of silicic acid, and while it may include polysilicates is quite different from the siloxane polymers of the present invention.
No art was found that teaches altering the internal structures of wood to increase the strength of the wood by contacting the wood with a siloxane polymer optionally diluted with a hydrocarbon solvent carrier, and optionally a naturally occurring oil. A method and composition to practice the novel treatment are described below, and produce novel articles of manufacture are set out below.
SUMMARY OF THE INVENTION
The invention provides a method for increasing strength in wood that comprises contacting with the wood to be treated with a copolymer of silicone units having the general formula: (M a D b T c Q d ) x where M is R 3 SiO 1/2 —; D is R 2 SiO—; T is RSiO 3/2 —; Q is Si(O 1/2 ) 4 —; R is a generalized organic radical selected from: linear or branched hydrocarbon radicals of 1-8 carbons containing 0-1 degree of unsaturation, or phenyl, or trifluoropropyl radicals; a, b, c, d are real numbers and further provided the ratio of a/(c+d) is between 0 and 4; the ratio of b to the rest is not subject to limitation provided the final base viscosity is between 50-3500 cSt; and at least one R group of each molecule must be a hydrolysable group; and maintaining the contact for a time sufficient to establish a change in the wood which is reflected in an increase in at least one measurable parameter reflecting an increase in the strength of the wood over an untreated wood from the same lot. Preferably the method further comprises mixing a cross-linking agent with the copolymer that comprises a siloxane polymer of the general formula: (M a D b T c Q d ) x meeting the following parameters apply: the ratio of a/(c+d) is between 0 and 4; the ratio of b to the rest is not subject to limitation provided the final cross-linking agent viscosity is below 350 cSt; and R is a generalized organic radical selected from: linear or branched hydrocarbon radicals of 1-8 carbons containing 0-1 degree of unsaturation, or phenyl, or trifluoropropyl radicals and at least one R group of each molecule must be a hydrolysable. It is also preferred to provide a crosslinking catalyst mixed with the copolymer. Any crosslinking catalyst known in the art may be used however preferred catalysts are tetraalkyl titanates or tetraalkyl zirconates where the alkyl groups may be the same or different. This mode of treatment provides a surface treatment and in some woods permeation of the wood is possible with some undiluted polymers; however, it is generally preferred to dilute the polymer with a solvent. While an aqueous solvent or even high pressure steam might be used, hydrocarbon solvents are preferred.
Because the viscosity of the copolymer may decrease or prevent penetration to the interior of the wood, it is desirable to dilute the copolymer with a hydrocarbon solvent. Use of a hydrocarbon solvent also decreases the rate of undesirable side reactions such as gel formation. Although any hydrocarbon solvent that carries the copolymer into cellulose fiber structures, such as wood, may be used the preferred solvents are aliphatic solvents composed primarily of C 7 -C 16 paraffinic, cycloparaffinic and isoparaffinic hydrocarbons containing less than about 0.5% aromatic hydrocarbons. More preferably, the aliphatic solvent is composed primarily of C 9 -C 14 , paraffinic, cycloparaffinic and isoparaffinic hydrocarbons and of those range of C 10 -C 13 is preferred. The current most preferred solvent is Conosol 145 marketed by Penreco, Inc, of Houston, Tex. Optionally additional benefits maybe obtained by adding to the treatment mixture a natural product oil selected from the group consisting of almond bitter oil, anise oil, basil oil, bay oil, caraway oil, cardamom oil, cedar oil, celery oil, chamomile oil, cinnamon oil, citronella oil, clove oil, coriander oil, cumin oil, dill oil, eucalyptus oil, fennel oil, ginger oil, grapefruit oil, lemon oil, lime oil, mint oil, parsley oil, peppermint oil, pepper oil, rose oil, spearmint oil (menthol), sweet orange oil, thyme oil, turmeric oil, oil of wintergreen, juniper oil, tall oil, pine oil; a synthetic natural product oil mimic that comprises at least one synthetically produced or isolated chemical identified as a component of a natural product oil elected from the group consisting of almond bitter oil, anise oil, basil oil, bay oil, caraway oil, cardamom oil, cedar oil, celery oil, chamomile oil, cinnamon oil, citronella oil, clove oil, coriander oil, cumin oil, dill oil, eucalyptus oil, fennel oil, ginger oil, grapefruit oil, lemon oil, lime oil, mint oil, parsley oil, peppermint oil, pepper oil, rose oil, spearmint oil (menthol), sweet orange oil, thyme oil, turmeric oil, oil of wintergreen, juniper oil, tall oil, pine oil. Preferred oils are cedar oil, cinnamon oil, citronella oil, clove oil, eucalyptus oil, juniper oil, tall oil, and pine oil. The most preferred oil is cedar oil.
In the copolymer the R groups may be the same or different and each is a lower alkyl group preferably of no more that four carbons. Especially preferred are those copolymers wherein all non-terminal copolymer R groups are methyl. In the preferred cross-linking agent each has an R group in an alkoxy group that is an alkyl group comprising from 1 to 4 carbon atoms. Especially preferred cross-linking agents further comprise methyl groups at each non-alkoxy position.
The invention also provides novel articles of manufacture comprising wood processed according to the various embodiments summarized above. Treatment according to the methods of the invention generates polymers within the structural matrix of the wood which increase the strength of the wood by increased cohesion of the wood fibers to each other.
DETAILED DESCRIPTION OF THE INVENTION
General Description of the Invention
In order to understand the invention at its most basic level it is importation to understand the basic properties of wood. According to a standard text, “Construction: Principles, Materials, and Methods” by Simmons, H. Leslie.; Olin, Harold Bennett, New York, N.Y., John Wiley & Sons, Inc. (US), 2001, Chapter 6 page 366 et seq., {Cited below as Simmons et al.} (Captions deleted from quotation. “ . . . ” indicates deletions other than captions and [ ] indicates insertions or change in case), “ . . . [w]ood cells, or fibers, are primarily cellulose cemented together with lignin. The wood structure is about 70% cellulose, between 12% and 28% lignin, and up to 1% ash-forming materials. These constituents give wood its hygroscopic properties, its susceptibility to decay, and its strength. The bond between individual fibers is so strong that when tested in tension they commonly tear apart rather than separate. The rest of wood, although not part of its structure, consists of extractives that give different species distinctive characteristics such as color, odor, and natural resistance to decay.
It is possible to dissolve the lignin in wood chips using chemicals, thus freeing the cellulose fibers. By further processing, these fibers can then be turned into a pulp from which paper and paperboard products are made. It is also possible to chemically convert cellulose so that it may be used to make textiles (such as rayon), plastics, and other products that depend on cellulose derivatives.”
Just as it is possible to dissolve the lignin in wood chips and release the wood fibers it is also possible to add to the cohesion of the wood fibers by adding polymeric materials to the internal structure of the wood and strengthens the wood as a result. The treatment of the present invention results in increased strength for new growth lumber, making it a useful replacement of old growth materials.
(Continue)
EXAMPLE 1
A copolymer solution suitable for treating wooden materials according the invention is prepared by slowly adding 20 parts of a silicone polymer obtained from GT Products, Inc. of Grapevine, Tex. designated X5814 to 80 parts of Conosol 145. When the addition is complete, 4 foot sections cut from building grade 8 foot pine 2×4s are immersed in a tank of circulating solution for one hour and dried to constant weight. The untreated 4 ft section of each 2×4 was market and used as a control in subsequent tests.
Randomly selected treated and the matching untreated 2×4s are split and the interior portions of the split wood was sprayed with water. The treated wood showed water beading even in the center of the material while all surfaces of the untreated portions were readily wet, showing complete penetration of the copolymer to the interior of the wood.
EXAMPLE 2
Insect Protection and Interior Penetration
A solution containing 80 parts Conosol 145, 15 parts X5814 and 5 parts Cedar Oil available from CedarCide, Inc. of Spring, Tex. was prepared as described in example 2. When the matched 2×4s were split the beading of water sprayed on the interior surfaces demonstrated penetration of the copolymer to all portions of the wood.
When filter papers composed of cellulose fibers were treated with the mixture and tested against untreated controls, worker termites readily feed on the untreated paper but no feeding was observed on the treated papers.
EXAMPLE 3
Strength Increase
Substantially equivalent nominal 8 feet Pine 2×4s were purchased from a retail chain home improvement center in the Houston, Tex. metropolitan area. Randomly selected boards were cut into two 4 foot sections and marked, one section was retained as a control and the other was treated according to the invention by immersion in a composition of 80% Conosol 145, 15% X5814, and 5% cedar wood oil for one hour, and then being permitted to air dry for several days.
The 4 foot section boards were then tested to breaking for strength retention in static bending. The test pieces were supported at the ends and a hydraulic jack with a gauge indicated the applied pressure was applied at the center until the test piece broke. Two separate sample sets of short leaf southern pine were tested. The pressure was applied to the center of the span on the 4 inch width, toward the 2 inch dimension. Sample 1 untreated failed at 400 pounds applied pressure after bending 2.25 in, and broke cleanly in to two separate pieces. Sample 1 treated failed at 900 pounds after bending 1.25 in. and the break was with long shards, with many bent shards remaining attached. Sample 2 untreated failed at 600 pounds with a 1.25 in bend, and again broke cleanly. Sample 2 treated failed at 2000 pounds, and again splintered rather than breaking cleanly. Examination of the broken, treated samples showed that the treatment was distributed through out the piece with no evidence of untreated areas.
EXAMPLE 4
Hygroscopic Behavior
Two samples of 22.5 mm×89 mm (1 in. by 4 in.) southern short leaf pine were dried to constant weight by heating in an oven at 110 deg. C. and weighing daily until no weight change was observed. One sample of the wood was then treated as described above, dried for several days and then placed in a chamber maintained at 100% humidity. The samples were weighed daily and the weights in grams are reported in table 1 below.
TABLE 1
Sample 1 2 3 4 5 6 7
#45-A-1 298 298 298 298 298 299 298
untreated 285 293 297 301 306 308 310
As shown above the treated sample did not gain weight by absorbing moisture from the atmosphere, while the untreated control showed the typical hygroscopic behavior of wood.
A copolymer solution suitable for treating wooden materials according the invention is prepared by slowly adding 20 parts of a silicone polymer obtained from GT Products, Inc. of Grapevine, Tex. designated X5814 to 80 parts of Conosol 145. When the addition is complete, 4 foot sections cut from building grade 8 foot pine 2×4s are immersed in a tank of circulating solution for one hour and dried to constant weight. The untreated 4 ft section of each 2×4 was market and used as a control in subsequent tests.
Randomly selected treated and the matching untreated 2×4s are split and the interior portions of the split wood was sprayed with water. The treated wood showed water beading even in the center of the material while all surfaces of the untreated portions were readily wet, showing complete penetration of the copolymer to the interior of the wood.
EXAMPLE 2
Insect Protection and Interior Penetration
A solution containing 80 parts Conosol 145, 15 parts X5814 and 5 parts Cedar Oil available from CedarCide, Inc. of Spring, Tex. was prepared as described in example 2. When the matched 2×4s were split the beading of water sprayed on the interior surfaces demonstrated penetration of the copolymer to all portions of the wood.
When filter papers composed of cellulose fibers were treated with the mixture and tested against untreated controls, worker termites readily feed on the untreated paper but no feeding was observed on the treated papers.
EXAMPLE 3
Strength Increase
Substantially equivalent nominal 8 feet Pine 2×4s were purchased from a retail chain home improvement center in the Houston, Tex. metropolitan area. Randomly selected boards were cut into two 4 foot sections and marked, one section was retained as a control and the other was treated according to the invention by immersion in a composition of 80% Conosol 145, 15% X5814, and 5% cedar wood oil for one hour, and then being permitted to air dry for several days.
The 4 foot section boards were then tested to breaking for strength retention in static bending. The test pieces were supported at the ends and a hydraulic jack with a gauge indicated the applied pressure was applied at the center until the test piece broke. Two separate sample sets of short leaf southern pine were tested. The pressure was applied to the center of the span on the 4 inch width, toward the 2 inch dimension. Sample 1 untreated failed at 400 pounds applied pressure after bending 2.25 in, and broke cleanly in to two separate pieces. Sample 1 treated failed at 900 pounds after bending 1.25 in. and the break was with long shards, with many bent shards remaining attached. Sample 2 untreated failed at 600 pounds with a 1.25 in bend, and again broke cleanly. Sample 2 treated failed at 2000 pounds, and again splintered rather than breaking cleanly. Examination of the broken, treated samples showed that the treatment was distributed through out the piece with no evidence of untreated areas.
EXAMPLE 4
Hygroscopic Behavior
Two samples of 22.5 mm×89 mm (1 in. by 4 in.) southern short leaf pine were dried to constant weight by heating in an oven at 110 deg. C. and weighing daily until no weight change was observed. One sample of the wood was then treated as described above, dried for several days and then placed in a chamber maintained at 100% humidity. The samples were weighed daily and the weights in grams are reported in table 1 below.
TABLE 1
Sample 1 2 3 4 5 6 7
#45-A-1 298 298 298 298 298 299 298
untreated 285 293 297 301 306 308 310
As shown above the treated sample did not gain weight by absorbing moisture from the atmosphere, while the untreated control showed the typical hygroscopic behavior of wood.
谢谢！ 说来见笑 本人的英语水平实在很囧 ----------
好象听说有人为了让肉多些水分而加了什么添加剂在水里吗？ 这个用在木材也可以吧
好象听说有人为了让肉多些水分而加了什么添加剂在水里吗？ 这个用在木材也可以吧
这个是往木材里注水溶性化学剂的美国专利：
http://www.freepatentsonline.com/4303705.html
http://www.freepatentsonline.com/4303705.html
烤干～
原帖由 花男胖虎 于 2008-9-7 21:34 发表
谢谢！ 说来见笑 本人的英语水平实在很囧 ----------
好象听说有人为了让肉多些水分而加了什么添加剂在水里吗？ 这个用在木材也可以吧
上面贴得是木材加硬的专利。马上贴一个注水（化学剂）的专利。
原帖由 lqvod 于 2008-9-8 11:12 发表
把它泡在水里，煮啊煮啊煮啊煮啊煮啊煮啊煮啊煮啊煮啊煮啊煮
温水浸泡可以一试:D
注水（化学剂）的专利
http://www.freepatentsonline.com/4303705.html
Title:
Treatment of wood with water-borne preservatives
Document Type and Number:
United States Patent 4303705
Abstract:
A process for the treatment of wood is disclosed in which water-borne wood treatment materials, such as CCA salts, are forced into the wood under pressure and the water-borne wood treatment materials are held within the wood under pressure until they are deposited as by precipitation or chemical affixation. The precipitation or chemical affixation step is conducted at elevated temperatures. The elevated temperatures may be established by heating the wood treatment materials while they are in contact with the wood, by draining the wood treatment materials from external contact with the wood, while maintaining a sufficient pressure to prevent kickback and heating the wood as by steaming or by submerging the wood in a heated aqueous bath. If a heated aqueous bath is used it may advantageously contain additional wood treatment materials such as wood-softening agents, antichecking agents, filmformers, coloring agents, dimensional stabilizers, flame-retardants, antistatic agents and the like.
In a preferred embodiment, the wood is placed under an initial pressure, lower than the impregnation pressure, so that the kick-back is maximized and the liquid retained within the wood is minimized.
Inventors:
Kelso Jr., William C. (14 Bulldog Dr., Starkville, MS, 39759)
Application Number:
05/836986
Publication Date:
12/01/1981
Filing Date:
09/27/1977
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Referenced by:
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Export Citation:
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Primary Class:
427/351
Other Classes:
427/370, 427/440, 427/397
International Classes:
B27K3/08; B27K3/32; B27K3/52; B27K3/02; B27K3/16; B05D3/12; B05D1/18; B05D3/02
Field of Search:
427/325, 427/331, 427/440, 427/441, 427/297, 427/370, 427/397, 427/351, 21/7
US Patent References:
2799597 Method of impregnating wood with wood-preserving oil July, 1957 Walker et al. 427/441
2909450 Impregnating solutions and method of impregnation therewith October, 1959 Goldstein 427/294
3080212 Treatment of wood with hot chromated copper arsenate solutions March, 1963 Oberley et al. 21/7
3200003 Process for impregnating wood with pentachlorophenol and composition therefor August, 1965 Bescher 427/440
3560251 February, 1971 Hager 427/351
3874908 COMPOSITION AND METHOD FOR MAINTAINING A CONSTANT CONCENTRATION OF AGENTS AND AMOUNT OF SOLVENT IN A WOOD TREATING PROCESS April, 1975 Liddell 21/7
3968276 Process for the preservation of wood July, 1976 Allen 427/440
4062991 Treatment of wood December, 1977 Kyte et al. 427/440
Foreign References:
CA613300 January, 1961 427/440
Primary Examiner:
Lusignan, Michael R.
Claims:
I claim:
1. A process for treating wood with water-borne materials, comprising;
placing the wood in a pressure vessel;
introducing the water-borne materials into the vessel and submerging the wood;
raising the pressure within the vessel and impregnating the wood with the water-borne materials until a desired gross absorption is achieved;
heating the interior of the vessel to a temperature of at least 150° F.;
maintaining the temperature and pressure after the gross absorption has been achieved for at least an hour and until a major portion of the water-borne materials become affixed to or precipitated on the wood; and
relieving the pressure and collecting the kick-back.
2. A process according to claim 1 wherein at least 90% of the water-borne materials of the solution become fixed to or precipitated on the wood.
3. A process for treating wood in accordance with claim 1 wherein the water-borne materials are drained from external contact with the wood while maintaining a pressure within the vessel sufficient to prevent kick-back from occurring prior to the time the temperature and pressure are established to affix or precipitate the water-borne materials on the wood.
4. A process according to claim 1 in which the interior of the vessel is heated by heating the water-borne materials while they are in contact with the wood.
5. A process for treating wood in accordance with claim 4 wherein the water-borne materials are drained from the pressure vessel after the water-borne materials become affixed to or precipitated on the wood while a sufficient pressure is maintained to avoid kick-back and thereafter the pressure is relieved and the kick-back is separately collected.
6. A process according to claim 1 wherein the heating is from 180° F. to 240° F.
7. A process according to claim 1 wherein the heating is from 200° F. to 230° F.
8. A process according to claim 1 wherein the water-borne materials are CCA salts.
9. A process according to claim 1 wherein the water-borne materials pentachlorophenol or its salts.
10. A process according to claim 1 wherein the solution is drained from external contact with the wood while maintaining a sufficient pressure to prevent kick-back and the interior of the vessel is then heated by submerging the wood in a heated aqueous bath.
11. A process according to claim 9 wherein the aqueous bath includes water-borne treatment materials.
12. A process according to claim 10 wherein the water-borne wood treatment materials include wood softening agents, antichecking agents, film formers, coloring agents, dimensional stabilizers, flame retardants or antistatic agents.
Description:
FIELD OF THE INVENTION
This invention relates to the pressure impregnation of wood with water-borne wood treatment materials to improve the properties of the wood. More particularly, this invention relates to a modified empty-cell process for the impregnation of wood in which water-borne wood treatment materials, such as CCA salts, are deposited within the wood, as by precipitation or chemical affixation, during a separate and distinct phase of the pressure impregnation cycle which is conducted prior to the time that kickback is permitted.
DESCRIPTION OF THE PRIOR ART
It has been common practice for many years to impregnate wood with preservatives and the like by utilizing pressure impregnation processes. The impregnants are selected to reduce decay and rot of the wood; to protect the wood from attack by fungus, micro-organisms and other pests; and to improve the properties of the wood as by giving it greater dimensional stability, preventing checking, or making it less flammable. The pressure impregnation processes are advantageous as compared with nonpressure methods in that they achieve a deeper and more uniform penetration and a higher absorption of the treatment material in the wood in a comparatively short period of time.
The various processes for the pressure impregnation of wood are usually classified as being either "full-cell" or "empty-cell" processes. In the full-cell process, the liquid forced into the wood is largely retained by the wood after impregnation, whereas in the empty-cell process, most of the treatment liquid is expelled from the wood after impregnation. The terms "full" and "empty" derive from the fact that the cells of the wood are substantially filled with impregnants in the full-cell process, but tend only to be coated with the impregnant in the empty-cell process.
The full-cell process makes use of a vacuum/pressure impregnation cycle in which the wood is first placed under vaccum and then, without admitting air, the treatment vessel is filled with the treatment liquid. After the wood is fully immersed in the liquid, the pressure is increased to perhaps ten atmospheres or so, and the liquid is forced into the wood. After the wood has been treated to refusal, or until a predetermined gross absorption of the treatment liquid has been achieved, the pressure is relieved and the treatment fluid is drained from the vessel. Usually a short vacuum cycle follows to remove excess liquid from the surface of the wood.
In distinction to the full-cell process, the empty-cell process does not make use of an initial vacuum, but rather, as most commonly practiced, the wood is placed under pressure prior to the time that it is contacted with the treatment liquid. While maintaining this initial pressure, the treatment vessel is filled with the treatment liquid and the pressure is increased to a second higher pressure so that the treatment liquid is forced into the wood against the air pressure initially established within the wood. As a result, when the pressure is relieved at the end of the impregnation cycle, the air compressed within the wood expands and expels much of the liquid that was forced into the wood. (Sometimes the empty-cell process is modified by omitting the initial pressurization of the wood before impregnation.) Usually, as is the case with the full-cell treatment, a vacuum is pulled on the treatment vessel at the end of the process to increase the recovery of the treatment fluid and shorten the period of time during which the fluid will drip from the surface of the wood.
The wood impregnated by the empty-cell process differs from the wood of the full-cell process in that the treated wood is not saturated with the treatment liquid. The empty-cell process is therefore especially advantageous when treating wood with water-borne materials since the wood, after treatment, is ready for shipment, further treatment or immediate use since there is no large quantity of water which must be removed from the wood. On the other hand, the full-cell process is used when it is the purpose of the impregnation process to keep as much of the treatment liquid in the wood as possible, such as when the impregnant is creosote or another petroleum-based preservative.
The term of art used in describing the liquid that is expelled from the interior of the wood after the pressure has been relieved in the empty-cell process is "kickback". When treating wood with water-soluble preservatives, such as CCA salts, kickback is undesirable because the kickback will include water-soluble reducing substances leached from the wood (e.g., hemicelluloses) which will react with the CCA salts and precipitate a dense sludge that will foul the equipment. (For the purposes of this specification and the appended claims, "CCA salts" is used to mean not only the standard chromium/copper/arsenic salts, but also modifications of these salts including those containing other soluble metal ions such as zinc salts.) In current practice, the kickback is collected in the tank containing the working treatment liquid and the insoluble material must periodically be removed between treatment cycles. It is desirable to make use of the kickback to utilize the residual salts and also because of the toxicity of the kickback and the hazard its discharge would pose to the environment. For these reasons, it has been standard practice to utilize the full-cell process for impregnating wood with CCA salts since, other than the small amount of vacuum drip, there is no kickback.
Another difficulty encountered when the kickback is reused is that the several salts used in treatment solutions, particularly the CCA salts, are extracted by the wood at different rates, requiring the kickback to be analyzed and the balance between the several salts restored before reuse.
It is for these reasons--that is, minimizing the amount of kickback liquid that must be treated forrecycling or disposal--that full-cell pressure impregnation processes are conventionally used to impregnate wood with water-soluble wood preservatives such as CCA salts.
Unfortunately, there are disadvantages attendant to the full-cell process when the object is to deposit the water-borne materials of the treatment liquid in the wood rather than to retain the liquid within the wood, among which the following can be listed:
The weight of the wood is greatly increased when it is filled with a treatment liquid, such as water, and, as a result, the wood must be dried in kilns or left to air-dry for a number of months to make shipment reasonably economic.
It is sometimes desirable to follow the initial impregnation of the wood with a second impregnation. For example, to achieve maximum preservation of wood for marine purposes, wood is first treated with a CCA salt and later impregnated with creosote. However, before any useful amounts of creosote can be driven into the wood, the retained water from the CCA salt treatment must be removed, either by costly kiln drying or lengthy air drying.
CCA salts tend to discolor wood during a drying operation. This discoloration occurs due to the migration of the salts to the surface of the wood during drying. The discoloration and color changes in the wood are believed to be photoactivated and any portion of the surface of the wood that is exposed to sunlight will turn a different color from those portions that are in the shade. This largely destroys the value of the wood for those uses in which the appearance of the wood is important.
Workers who handle wood saturated in the full-cell process may find it necessary to wear protective gear, such as gloves and aprons, if they have a sensitivity to the impregnating salts.
But even with these and other limitations inherent in practicing the full-cell process, the full-cell process is usually preferred over the empty-cell process simply because returning the kickback to the working solution or otherwise disposing of the kickback presents even greater problems.
SUMMARY OF THE INVENTION
Accordingly, it is an object of this invention to provide a modified empty-cell process for the impregnation of wood.
Another object of this invention is to provide an empty-cell type process for the pressure impregnation of wood in which the liquid-borne active materials are deposited on the wood as by precipitation or chemical affixation before permitting kickback.
Another object of this invention is to provide improved methods and means for the pressure impregnation of wood with water-borne salt preservatives in which the retention of the salts within the wood is maximized.
Another object of this invention is to provide improved methods and means for the pressure impregnation of wood with water-borne salt preservatives in which the liquid retained within the wood is minimized.
Another object of this invention is to provide a process for the pressure impregnation of wood with water-borne preservatives which makes possible, during the treatment process, the treatment of the wood with other wood treatment materials.
Briefly, these and other objects of this invention are achieved by pressure impregnating wood with a water-borne treatment material, detaining the impregnated wood under pressure for a sufficient time for the water-borne treatment materials to react with or otherwise become fixed to the wood, and finally, after the treatment materials have completed at least their initial reaction with the wood, relieving the pressure and permitting kickback to occur. By these means, the amount of water-borne treatment materials in the kickback is reduced to a minimum and the need to process the kickback for recycling or discharge is largely avoided.
In its simplest form, this invention normally occur over a number of weeks following treatment and exposure can be made to occur during the impregnation process, thus making it practical to use the basic empty-cell process since the kickback will be substantially free of precipitating reaction products and high levels of unreacted treatment salts. In one embodiment of this invention, the treatment liquid, after impregnation, is drained from contact with the wood while maintaining sufficient pressure to prevent kickback. After the treatment liquid is removed from contact with the wood, the wood is heated as by steaming to increase the temperature of the wood and increase the rate and efficiency of the reactions. One reason that the treatment liquid may be drained from contact with the wood prior to the time the wood is heated is due to the belief, as is universally held by those skilled in the art, that CCA salts cannot be heated to above about 120° F. without causing precipitation of the CCA salts. This belief may have come about since, if CCA salts are heated prior to the time they are brought in contact with the wood, they readily precipitate within the wood at the start of the impregnation process, clog the outer cellular structure of the wood and thus make it difficult to impossible to obtain the desired degree and depth of impregnation into the wood.
It has now been discovered that CCA salts do not precipitate when heated if they are not in contact with wood at the time the heating takes place. Accordingly, in another embodiment of this invention the treatment solution may be used as the heat exchange medium (which is heated only after impregnation) for accelerating the chemical reactions within the wood. While some precipitation of the CCA salts may take place at the surface of the wood after impregnation and during subsequent heating, such precipitation is at worst nominal and it has proven possible to use the treatment liquid, after impregnation, as the heat exchange medium to achieve the desired chemical reactions in the wood before kickback.
In yet another embodiment of the instant invention, the treatment liquid may be drained away from contact with the wood while impregnating pressures are maintained to prevent kickback, and the wood is then heated to achieve the desired chemical reactions by introducing an aqueous heat exchange liquid into the treatment vessel which, if desired, may contain other wood treatment materials such as wood-softening agents, antichecking agents, film-formers, coloring agents, dimensional stabilizers, flame-retardants, antistatic agents, and the like. By this means, a secondary treatment of at least the surface of the wood may be provided for during the same treatment procedure in which the wood is given a primary treatment.
EXAMPLE I
A charge of kiln-dry (15% moisture content) Southern pine tomato stakes and grape stakes consisting of thirty tomato stakes measuring 1"×1"×72"(1.25 cubic feet) and 15 grape stakes measuring 1 5/8"×15/8"×72"(1.65 cubic feet) was given a modified empty-cell treatment with a 2.0% (oxide basis) solution of CCA as follows:
An initial pressure of 10 p.s.i. air was introduced into the treatment vessel and held for five minutes. The vessel was then filled with the CCA solution without relieving the initial pressure, and the pressure was increased to 100 p.s.i. in a forty-five minute period by increasing the pressure 10 p.s.i. at five minute intervals.
(Continue)
http://www.freepatentsonline.com/4303705.html
Title:
Treatment of wood with water-borne preservatives
Document Type and Number:
United States Patent 4303705
Abstract:
A process for the treatment of wood is disclosed in which water-borne wood treatment materials, such as CCA salts, are forced into the wood under pressure and the water-borne wood treatment materials are held within the wood under pressure until they are deposited as by precipitation or chemical affixation. The precipitation or chemical affixation step is conducted at elevated temperatures. The elevated temperatures may be established by heating the wood treatment materials while they are in contact with the wood, by draining the wood treatment materials from external contact with the wood, while maintaining a sufficient pressure to prevent kickback and heating the wood as by steaming or by submerging the wood in a heated aqueous bath. If a heated aqueous bath is used it may advantageously contain additional wood treatment materials such as wood-softening agents, antichecking agents, filmformers, coloring agents, dimensional stabilizers, flame-retardants, antistatic agents and the like.
In a preferred embodiment, the wood is placed under an initial pressure, lower than the impregnation pressure, so that the kick-back is maximized and the liquid retained within the wood is minimized.
Inventors:
Kelso Jr., William C. (14 Bulldog Dr., Starkville, MS, 39759)
Application Number:
05/836986
Publication Date:
12/01/1981
Filing Date:
09/27/1977
View Patent Images:
Images are available in PDF form when logged in. To view PDFs, Login or Create Account (Free!)
Referenced by:
View patents that cite this patent
Export Citation:
Click for automatic bibliography generation
Primary Class:
427/351
Other Classes:
427/370, 427/440, 427/397
International Classes:
B27K3/08; B27K3/32; B27K3/52; B27K3/02; B27K3/16; B05D3/12; B05D1/18; B05D3/02
Field of Search:
427/325, 427/331, 427/440, 427/441, 427/297, 427/370, 427/397, 427/351, 21/7
US Patent References:
2799597 Method of impregnating wood with wood-preserving oil July, 1957 Walker et al. 427/441
2909450 Impregnating solutions and method of impregnation therewith October, 1959 Goldstein 427/294
3080212 Treatment of wood with hot chromated copper arsenate solutions March, 1963 Oberley et al. 21/7
3200003 Process for impregnating wood with pentachlorophenol and composition therefor August, 1965 Bescher 427/440
3560251 February, 1971 Hager 427/351
3874908 COMPOSITION AND METHOD FOR MAINTAINING A CONSTANT CONCENTRATION OF AGENTS AND AMOUNT OF SOLVENT IN A WOOD TREATING PROCESS April, 1975 Liddell 21/7
3968276 Process for the preservation of wood July, 1976 Allen 427/440
4062991 Treatment of wood December, 1977 Kyte et al. 427/440
Foreign References:
CA613300 January, 1961 427/440
Primary Examiner:
Lusignan, Michael R.
Claims:
I claim:
1. A process for treating wood with water-borne materials, comprising;
placing the wood in a pressure vessel;
introducing the water-borne materials into the vessel and submerging the wood;
raising the pressure within the vessel and impregnating the wood with the water-borne materials until a desired gross absorption is achieved;
heating the interior of the vessel to a temperature of at least 150° F.;
maintaining the temperature and pressure after the gross absorption has been achieved for at least an hour and until a major portion of the water-borne materials become affixed to or precipitated on the wood; and
relieving the pressure and collecting the kick-back.
2. A process according to claim 1 wherein at least 90% of the water-borne materials of the solution become fixed to or precipitated on the wood.
3. A process for treating wood in accordance with claim 1 wherein the water-borne materials are drained from external contact with the wood while maintaining a pressure within the vessel sufficient to prevent kick-back from occurring prior to the time the temperature and pressure are established to affix or precipitate the water-borne materials on the wood.
4. A process according to claim 1 in which the interior of the vessel is heated by heating the water-borne materials while they are in contact with the wood.
5. A process for treating wood in accordance with claim 4 wherein the water-borne materials are drained from the pressure vessel after the water-borne materials become affixed to or precipitated on the wood while a sufficient pressure is maintained to avoid kick-back and thereafter the pressure is relieved and the kick-back is separately collected.
6. A process according to claim 1 wherein the heating is from 180° F. to 240° F.
7. A process according to claim 1 wherein the heating is from 200° F. to 230° F.
8. A process according to claim 1 wherein the water-borne materials are CCA salts.
9. A process according to claim 1 wherein the water-borne materials pentachlorophenol or its salts.
10. A process according to claim 1 wherein the solution is drained from external contact with the wood while maintaining a sufficient pressure to prevent kick-back and the interior of the vessel is then heated by submerging the wood in a heated aqueous bath.
11. A process according to claim 9 wherein the aqueous bath includes water-borne treatment materials.
12. A process according to claim 10 wherein the water-borne wood treatment materials include wood softening agents, antichecking agents, film formers, coloring agents, dimensional stabilizers, flame retardants or antistatic agents.
Description:
FIELD OF THE INVENTION
This invention relates to the pressure impregnation of wood with water-borne wood treatment materials to improve the properties of the wood. More particularly, this invention relates to a modified empty-cell process for the impregnation of wood in which water-borne wood treatment materials, such as CCA salts, are deposited within the wood, as by precipitation or chemical affixation, during a separate and distinct phase of the pressure impregnation cycle which is conducted prior to the time that kickback is permitted.
DESCRIPTION OF THE PRIOR ART
It has been common practice for many years to impregnate wood with preservatives and the like by utilizing pressure impregnation processes. The impregnants are selected to reduce decay and rot of the wood; to protect the wood from attack by fungus, micro-organisms and other pests; and to improve the properties of the wood as by giving it greater dimensional stability, preventing checking, or making it less flammable. The pressure impregnation processes are advantageous as compared with nonpressure methods in that they achieve a deeper and more uniform penetration and a higher absorption of the treatment material in the wood in a comparatively short period of time.
The various processes for the pressure impregnation of wood are usually classified as being either "full-cell" or "empty-cell" processes. In the full-cell process, the liquid forced into the wood is largely retained by the wood after impregnation, whereas in the empty-cell process, most of the treatment liquid is expelled from the wood after impregnation. The terms "full" and "empty" derive from the fact that the cells of the wood are substantially filled with impregnants in the full-cell process, but tend only to be coated with the impregnant in the empty-cell process.
The full-cell process makes use of a vacuum/pressure impregnation cycle in which the wood is first placed under vaccum and then, without admitting air, the treatment vessel is filled with the treatment liquid. After the wood is fully immersed in the liquid, the pressure is increased to perhaps ten atmospheres or so, and the liquid is forced into the wood. After the wood has been treated to refusal, or until a predetermined gross absorption of the treatment liquid has been achieved, the pressure is relieved and the treatment fluid is drained from the vessel. Usually a short vacuum cycle follows to remove excess liquid from the surface of the wood.
In distinction to the full-cell process, the empty-cell process does not make use of an initial vacuum, but rather, as most commonly practiced, the wood is placed under pressure prior to the time that it is contacted with the treatment liquid. While maintaining this initial pressure, the treatment vessel is filled with the treatment liquid and the pressure is increased to a second higher pressure so that the treatment liquid is forced into the wood against the air pressure initially established within the wood. As a result, when the pressure is relieved at the end of the impregnation cycle, the air compressed within the wood expands and expels much of the liquid that was forced into the wood. (Sometimes the empty-cell process is modified by omitting the initial pressurization of the wood before impregnation.) Usually, as is the case with the full-cell treatment, a vacuum is pulled on the treatment vessel at the end of the process to increase the recovery of the treatment fluid and shorten the period of time during which the fluid will drip from the surface of the wood.
The wood impregnated by the empty-cell process differs from the wood of the full-cell process in that the treated wood is not saturated with the treatment liquid. The empty-cell process is therefore especially advantageous when treating wood with water-borne materials since the wood, after treatment, is ready for shipment, further treatment or immediate use since there is no large quantity of water which must be removed from the wood. On the other hand, the full-cell process is used when it is the purpose of the impregnation process to keep as much of the treatment liquid in the wood as possible, such as when the impregnant is creosote or another petroleum-based preservative.
The term of art used in describing the liquid that is expelled from the interior of the wood after the pressure has been relieved in the empty-cell process is "kickback". When treating wood with water-soluble preservatives, such as CCA salts, kickback is undesirable because the kickback will include water-soluble reducing substances leached from the wood (e.g., hemicelluloses) which will react with the CCA salts and precipitate a dense sludge that will foul the equipment. (For the purposes of this specification and the appended claims, "CCA salts" is used to mean not only the standard chromium/copper/arsenic salts, but also modifications of these salts including those containing other soluble metal ions such as zinc salts.) In current practice, the kickback is collected in the tank containing the working treatment liquid and the insoluble material must periodically be removed between treatment cycles. It is desirable to make use of the kickback to utilize the residual salts and also because of the toxicity of the kickback and the hazard its discharge would pose to the environment. For these reasons, it has been standard practice to utilize the full-cell process for impregnating wood with CCA salts since, other than the small amount of vacuum drip, there is no kickback.
Another difficulty encountered when the kickback is reused is that the several salts used in treatment solutions, particularly the CCA salts, are extracted by the wood at different rates, requiring the kickback to be analyzed and the balance between the several salts restored before reuse.
It is for these reasons--that is, minimizing the amount of kickback liquid that must be treated forrecycling or disposal--that full-cell pressure impregnation processes are conventionally used to impregnate wood with water-soluble wood preservatives such as CCA salts.
Unfortunately, there are disadvantages attendant to the full-cell process when the object is to deposit the water-borne materials of the treatment liquid in the wood rather than to retain the liquid within the wood, among which the following can be listed:
The weight of the wood is greatly increased when it is filled with a treatment liquid, such as water, and, as a result, the wood must be dried in kilns or left to air-dry for a number of months to make shipment reasonably economic.
It is sometimes desirable to follow the initial impregnation of the wood with a second impregnation. For example, to achieve maximum preservation of wood for marine purposes, wood is first treated with a CCA salt and later impregnated with creosote. However, before any useful amounts of creosote can be driven into the wood, the retained water from the CCA salt treatment must be removed, either by costly kiln drying or lengthy air drying.
CCA salts tend to discolor wood during a drying operation. This discoloration occurs due to the migration of the salts to the surface of the wood during drying. The discoloration and color changes in the wood are believed to be photoactivated and any portion of the surface of the wood that is exposed to sunlight will turn a different color from those portions that are in the shade. This largely destroys the value of the wood for those uses in which the appearance of the wood is important.
Workers who handle wood saturated in the full-cell process may find it necessary to wear protective gear, such as gloves and aprons, if they have a sensitivity to the impregnating salts.
But even with these and other limitations inherent in practicing the full-cell process, the full-cell process is usually preferred over the empty-cell process simply because returning the kickback to the working solution or otherwise disposing of the kickback presents even greater problems.
SUMMARY OF THE INVENTION
Accordingly, it is an object of this invention to provide a modified empty-cell process for the impregnation of wood.
Another object of this invention is to provide an empty-cell type process for the pressure impregnation of wood in which the liquid-borne active materials are deposited on the wood as by precipitation or chemical affixation before permitting kickback.
Another object of this invention is to provide improved methods and means for the pressure impregnation of wood with water-borne salt preservatives in which the retention of the salts within the wood is maximized.
Another object of this invention is to provide improved methods and means for the pressure impregnation of wood with water-borne salt preservatives in which the liquid retained within the wood is minimized.
Another object of this invention is to provide a process for the pressure impregnation of wood with water-borne preservatives which makes possible, during the treatment process, the treatment of the wood with other wood treatment materials.
Briefly, these and other objects of this invention are achieved by pressure impregnating wood with a water-borne treatment material, detaining the impregnated wood under pressure for a sufficient time for the water-borne treatment materials to react with or otherwise become fixed to the wood, and finally, after the treatment materials have completed at least their initial reaction with the wood, relieving the pressure and permitting kickback to occur. By these means, the amount of water-borne treatment materials in the kickback is reduced to a minimum and the need to process the kickback for recycling or discharge is largely avoided.
In its simplest form, this invention normally occur over a number of weeks following treatment and exposure can be made to occur during the impregnation process, thus making it practical to use the basic empty-cell process since the kickback will be substantially free of precipitating reaction products and high levels of unreacted treatment salts. In one embodiment of this invention, the treatment liquid, after impregnation, is drained from contact with the wood while maintaining sufficient pressure to prevent kickback. After the treatment liquid is removed from contact with the wood, the wood is heated as by steaming to increase the temperature of the wood and increase the rate and efficiency of the reactions. One reason that the treatment liquid may be drained from contact with the wood prior to the time the wood is heated is due to the belief, as is universally held by those skilled in the art, that CCA salts cannot be heated to above about 120° F. without causing precipitation of the CCA salts. This belief may have come about since, if CCA salts are heated prior to the time they are brought in contact with the wood, they readily precipitate within the wood at the start of the impregnation process, clog the outer cellular structure of the wood and thus make it difficult to impossible to obtain the desired degree and depth of impregnation into the wood.
It has now been discovered that CCA salts do not precipitate when heated if they are not in contact with wood at the time the heating takes place. Accordingly, in another embodiment of this invention the treatment solution may be used as the heat exchange medium (which is heated only after impregnation) for accelerating the chemical reactions within the wood. While some precipitation of the CCA salts may take place at the surface of the wood after impregnation and during subsequent heating, such precipitation is at worst nominal and it has proven possible to use the treatment liquid, after impregnation, as the heat exchange medium to achieve the desired chemical reactions in the wood before kickback.
In yet another embodiment of the instant invention, the treatment liquid may be drained away from contact with the wood while impregnating pressures are maintained to prevent kickback, and the wood is then heated to achieve the desired chemical reactions by introducing an aqueous heat exchange liquid into the treatment vessel which, if desired, may contain other wood treatment materials such as wood-softening agents, antichecking agents, film-formers, coloring agents, dimensional stabilizers, flame-retardants, antistatic agents, and the like. By this means, a secondary treatment of at least the surface of the wood may be provided for during the same treatment procedure in which the wood is given a primary treatment.
EXAMPLE I
A charge of kiln-dry (15% moisture content) Southern pine tomato stakes and grape stakes consisting of thirty tomato stakes measuring 1"×1"×72"(1.25 cubic feet) and 15 grape stakes measuring 1 5/8"×15/8"×72"(1.65 cubic feet) was given a modified empty-cell treatment with a 2.0% (oxide basis) solution of CCA as follows:
An initial pressure of 10 p.s.i. air was introduced into the treatment vessel and held for five minutes. The vessel was then filled with the CCA solution without relieving the initial pressure, and the pressure was increased to 100 p.s.i. in a forty-five minute period by increasing the pressure 10 p.s.i. at five minute intervals.
(Continue)
The excess preservative was removed while maintaining cylinder pressure at 100 p.s.i.
The gross absorption of the CCA solution during the pressurization period was 35.9 lbs/cu.ft.
The charge was steamed 11/2 hours at 100 p.s.i. pressure with the maximum temperature of 240° F. being reached in one hour and then held at this temperature for a half hour.
A kick-back sample taken at the end of the steaming cycle had a pH of 3.1.
The charge was exposed to a 26" Hg. vacuum for one hour before being removed and weighed to determine net solution retention. The net solution retention obtained during treatment was 10.22 lbs/cu.ft.
Analysis of the original treating solution and kick-back resulting from the treatment of this charge gave the following results:
______________________________________
% Reduction of: Sample pH CuO CrO 3 As 2 O 5 CuO CrO 3 As 2 O 5
______________________________________
Treatment
1.5 0.345 0.958 0.718 -- -- --
solution
Kick-back
3.1 0.021 0.016 0.019 93.9 98.3 97.4
______________________________________
EXAMPLE 2
Precipitation of Cu and Cr from acid copper chromate in kiln-dry (20% moisture content) Southern pine by steaming before permitting the kick-back to occur.
A piece of kiln-dry Southern pine 61/2" in diameter and 18" long was impregnated as follows:
A. Preservative Solution:
A 2.38% solution (oxide basis) of acid copper chromate was prepared from a commercial (Celcure) concentrate of this preservative containing 3.84% copper sulfate (anhydrous), 5.01% sodium dichromate (anhydrous), and 0.20% chromic acid (anhydrous) by dilution with water. The pH of this fresh solution was 3.4.
B. Impregnation Cycle:
40 p.s.i. initial air was held five minutes, the treatment vessel was filled with the preservative solution at this pressure, and the pressure was then increased to 140 p.s.i. and held for two hours.
Excess preservative solution was drained from the vessel while maintaining the cylinder pressure at 140 p.s.i.
A kick-back sample was taken at the end of the pressure period but before starting the steaming by momentarily reducing the pressure slightly. The pH of this kick-back sample was 3.85.
The gross absorption of preservative during the pressure period was 29.29 lbs/cu.ft.
The sample was steamed at 212° F. for three hours while maintaining 140 p.s.i. pressure on the cylinder.
A kick-back sample taken at the end of the steaming cycle had a pH of 5.45.
The sample was exposed to a 26" Hg. vacuum for one hour before being removed and weighed to determine net solution retention.
A sample of the drip obtained during the final vacuum had a pH of 5.50.
The net solution retention obtained during treatment was 9.09 lbs/cu.ft. so that the gross absorption was reduced by over 20 lbs/cu.ft.
A disc obtained from the middle of this sample after treatment was dried in an oven to determine its average moisture content. Its moisture content expressed as a percent of oven-dry weight was 40.3%.
Analysis of the samples obtained during the treatment of this sample for Cu and Cr gave the results indicated in the table below. In this table, Sample 1 was the original treatment solution; Sample 2 was the kick-back after impregnation but before steaming; Sample 3 was the kick-back after impregnation and steaming; and Sample 4 was the drip from the wood during final vacuum.
______________________________________
% Reduction % Reduction Sample pH % CuO of CuO % CrO 3 of CrO 3
______________________________________
1 3.40 0.717 -- 1.661 --
2 3.85 0.628 12.41 1.527 8.07
3 5.45 0.014 98.06 0.027 98.37
4 5.50 0.025 96.58 0.009 99.46
______________________________________
The disc obtained from this sample after treatment and steaming indicated complete penetration by the preservative.
EXAMPLE 3
In this example, the wood was given a pretreatment with Ba(OH) 2 prior to treatment with CCA to determine if the sugars could be precipitated in the wood so that they would not contaminate the kick-back.
A piece of kiln-dry Southern pine (20% mositure content) 51/2" in diameter and 18" long was impregnated as follows:
A. Ba(OH) 2 Solution:
A 0.50% of Ba(OH) 2 (anhydrous) solution was prepared from a 1.00% solution by dilution with water.
B. Ba(OH) 2 Impregnation Cycle:
20 p.s.i. initial air pressure was established and held for five minutes. The treatment vessel was charged with the Ba(OH) 2 solution and a pressure of 120 p.s.i. was established and held for two hours.
Excess Ba(OH) 2 solution was drained from the vessel while maintaining cylinder pressure at 120 p.s.i.
A kick-back sample was taken by momentarily reducing the pressure slightly at the end of the pressure period but before starting the steaming cycle. The pH of this kick-back sample was 12.4.
The gross absorption of the Ba(OH) 2 solution during the pressure period was 31.24 lbs/cu.ft.
The sample was steamed at 212° F. for three hours while maintaining 120 psi pressure on the cylinder.
A kick-back sample was taken at the end of the steaming cycle. The pH of this sample was 6.1.
The sample was exposed to a 26" Hg. vacuum for one hour before being removed and weighed to determine net solution retention.
The net solution retention obtained during treatment was 2.50 lbs/cu.ft.
The sample was replaced in the cylinder immediately following the above weighing and given an empty-cell treatment in accordance with this invention with a 2% (oxide basis) solution of CCA as follows:
C. CCA Impregnation Cycle:
20 p.s.i. initial air pressure was established and held for five minutes. The treatment vessel was charged with the CCA solution and a pressure of 120 p.s.i. was established and held for two hours.
Excess CCA solution drained from the vessel while maintaining cylinder pressure at 120 p.s.i.
A kick-back sample was taken at the end of the pressure period but before starting the steaming cycle by momentarily reducing the pressure slightly. The pH of this kick-back sample was 2.3.
The gross absorption of the CCA solution during the pressure period was 26.48 lbs/cu.ft.
The sample was steamed at 212° F. for three hours while maintaining 120 p.s.i. pressure on the cylinder.
A kick-back sample was taken at the end of the steaming cycle. The pH of this sample was 4.0.
The sample was exposed to a 26" Hg. vacuum for one hour before being removed and weighed to determine net retention of CCA solution.
The net CCA solution retention was 3.24 lbs/cu.ft., with the total gain in weight during both impregnation cycles being 9.45 lbs/cu.ft.
The sample was sawed at midlength to determine the depth of penetration of the CCA solution. The entire cross section was penetrated.
Analysis of the kick-back samples obtained during the CCA impregnation cycle gave the following results. In the table, Sample 1 was the original treatment solution; Sample 2 was the kick-back after impregnation; and Sample 3 was the kick-back after steaming.
______________________________________
% Reduction of: Sample pH CuO CrO 3 As 2 O 5 CuO CrO 3 As 2 O 5
______________________________________
1 1.6 0.329 0.916 0.689 -- -- --
2 2.3 0.163 0.604 0.428 50.46 34.06 37.88
3 4.0 0.000 0.002 0.003 100.00
99.56 99.56
______________________________________
Enough CCA concentrate was added to a portion of Sample 3 to bring its concentration up to 2.0% (oxide basis) to determine if the Cu, Cr and As would remain in solution. No precipitate occurred in this sample after two weeks' storage in the laboratory, indicating that the wood sugars were precipitated in the wood and did not, to any observable extent, contaminate the kick-back.
EXAMPLES 4-6
In Examples 4 through 6, samples of Southern pine wood were treated with CCA salts under varying process conditions, as shown in the following table. In this table, the column headed "Initial p.s.i." indicates the pressure to which the wood was exposed prior to impregnation. The column headed "Impregnation p.s.i." indicates the pressure that was established within the treatment vessel after the vessel had been filled with the treatment liquid. The "Steaming Temperature" was the ultimate temperature reached, over a period of about an hour, after the impregnation pressure was imposed. The "Holding Time" is the period of time that the vessel was maintained at the impregnation pressure and the steaming temperature.
The other columns indicate the percentage of the active ingredients in the initial treatment solution, the kick-back, and the percentage of the active ingredients that were retained within the wood. Note that in Examples 4 and 5 where the temperature of the treatment vessel was not increased above ambient, the deposition of the CCA salts did not begin to approach completion even after a holding time of as long as six hours. In contrast to this, Example 6 shows that at a steaming temperature of 210° F., well over 95% of the CCA salts were deposited in the wood after a holding time of only two hours.
________________________________________________________ __________________
TREATMENT RETAINED Ini- Impreg- Steam- Hold- SOLUTION KICK-BACK SALTS Ex- tial nation ing ing % % % % % % % % ample psi psi Temp. Time CuO CrO 3 As 2 O 5 CuO As 2 O 5 CuO CrO 3 As 2 O 5
________________________________________________________ __________________
4 10 100 None
3 hrs.
0.382
1.010
0.718
0.139
0.425
0.070
63.6
57.9
90.3
5 10 110 None
6 hrs.
0.331
0.962
0.692
0.096
0.338
0.170
71.1
64.8
75.5
6 10 120 210° F.
2 hrs.
0.314
0.904
0.819
0.011
0.006
0.017
96.5
99.3
97.9
________________________________________________________ __________________
EXAMPLE 7
A charge of air-dried (25% moisture) pine fence posts about 4"×8'6" in size were placed in a pressure vessel and an initial air pressure of 20 psi was introduced into the treatment vessel and held for about five minutes. The vessel was then filled with a CCA solution (see Table 1) without relieving the initial pressure, and the pressure was increased to 140 psi over a period of about 55 minutes. The temperature of the CCA impregnating solution was about 90° F. and the gross absorption achieved was 31.4 lb/cu.ft.
When the required gross absorption had been obtained steam was admitted to the coils in the cylinder and the CCA solution in the cylinder was heated to 200° F. within 30 minutes and this temperature was maintained for 60 minutes. No precipitation of CCA salts from the treatment solution was noted during this heating cycle.
At the end of the heating period, the CCA solution was removed from the cylinder without permitting the pressure on the system to change, following which the pressure on the system was released to collect the kickback separate from the CCA solution. The temperature of the kickback solution was 180° F. A final vacuum of 60 minutes at 25 in. Hg. followed after releasing the pressure on the system.
The wood was removed from the cylinder and weighed. It was determined that the net preservative solution retention was 7 lb/cu.ft.
Results of anaylses performed on the CCA before treatment, after treatment and heating and on a sample of the kickback after heating are contained in Table 1:
TABLE 1
______________________________________
Metal Content (% oxide basis) Solution pH CuO CrO 3 As 2 O 5 Total Salt
______________________________________
CCA before treatment
1.92 0.304 0.870 0.643 1.817
CCA after treatment
2.03 substantially the same as above
and heating
Kickback 4.18 0.008 0.017 0.022 0.047
______________________________________
An increment core was taken from midlength of each post for analysis for Cu, Cr and As retention after treatment. The cores were cut into 1/2" segments and similar segments were combined for analysis. Results for these analyses are contained in Table 2:
TABLE 2
______________________________________
Retention of Metals - lb/cu.ft. Depth from (Oxide Basis) Surface (inches) CuO CrO 3 As 2 O 5 Total Salt
______________________________________
0.0 to 0.5 0.161 0.352 0.251 0.765
0.5 to 1.0 0.123 0.244 0.019 0.385
1.0 to 1.5 0.074 0.177 0.014 0.265
______________________________________
The times, pressures and temperatures utilized in the above-described modified empty-cell process may vary substantially, depending upon the species of wood being treated and the nature of the treatment liquid. Also, the treatment times are temperature-dependent since the desired reactions generally take place faster at higher temperatures. By way of example, representative data has been obtained in treating Southern pine with CCA salts and it was found that temperatures ranging from about 150° F. to 250° F. are useful. At temperatures lower than these, the reaction rates are inconveniently slow, and at higher temperatures, damage may be done to the wood. A preferred temperature range for treating Southern pine with CCA salts is from about 180° F. to 240° F. and, more preferably still, from about 200° F. to 230° F.
Treatment times will vary considerably and, depending on the temperature used in the treatment cycle, satisfactory results have been obtained using treatment times of from about one to about seven hours. Longer times can, of course, be used, but in the interest of productivity of the process, no purpose is served in prolonging the treatment time after the desired reactions have neared or reached completion.
The modified empty-cell process of this invention has been described primarily with regard to the impregnation of wood with CCA salts, but it can readily be understood by those of ordinary skill in the wood treatment arts that the invention is of utility in treating wood with other wood preservatives such as, for example, pentachlorophenol. Further, the water-borne materials may include such things as wood-softening agents, antichecking agents, film-formers, coloring agents, flame retardants, antistatic agents, dimensional stabilizers, and other wood-treating agents. The process of this invention may also be used to leach materials, such as sugars, from wood, or, conversely, to precipitate sugars in the wood prior to a subsequent preservation step. The pH of the treatment liquid can be adjusted to maximize solubilization of the sugars and, if it is the object to fix the sugars in the wood, cations, such as barium or copper, may be included in the treatment liquid to form insoluble products with the sugars.
The modified empty-cell process of this invention makes it possible to conduct a plurality of sequential impregnations without the intervening drying or curing steps required in the full-cell process. For example, substantially immediately after wood is treated with CCA salts in accordance with this invention, it may be impregnated with oil-based preservatives. Another example would be to impregnate with preservative inorganic salts followed by a subsequent treatment with pentachlorophenol. This increases the degree of protection for the wood and is advantageous if aresenic salts must be excluded from the treatment liquid because of environmental hazards.
The gross absorption of the CCA solution during the pressurization period was 35.9 lbs/cu.ft.
The charge was steamed 11/2 hours at 100 p.s.i. pressure with the maximum temperature of 240° F. being reached in one hour and then held at this temperature for a half hour.
A kick-back sample taken at the end of the steaming cycle had a pH of 3.1.
The charge was exposed to a 26" Hg. vacuum for one hour before being removed and weighed to determine net solution retention. The net solution retention obtained during treatment was 10.22 lbs/cu.ft.
Analysis of the original treating solution and kick-back resulting from the treatment of this charge gave the following results:
______________________________________
% Reduction of: Sample pH CuO CrO 3 As 2 O 5 CuO CrO 3 As 2 O 5
______________________________________
Treatment
1.5 0.345 0.958 0.718 -- -- --
solution
Kick-back
3.1 0.021 0.016 0.019 93.9 98.3 97.4
______________________________________
EXAMPLE 2
Precipitation of Cu and Cr from acid copper chromate in kiln-dry (20% moisture content) Southern pine by steaming before permitting the kick-back to occur.
A piece of kiln-dry Southern pine 61/2" in diameter and 18" long was impregnated as follows:
A. Preservative Solution:
A 2.38% solution (oxide basis) of acid copper chromate was prepared from a commercial (Celcure) concentrate of this preservative containing 3.84% copper sulfate (anhydrous), 5.01% sodium dichromate (anhydrous), and 0.20% chromic acid (anhydrous) by dilution with water. The pH of this fresh solution was 3.4.
B. Impregnation Cycle:
40 p.s.i. initial air was held five minutes, the treatment vessel was filled with the preservative solution at this pressure, and the pressure was then increased to 140 p.s.i. and held for two hours.
Excess preservative solution was drained from the vessel while maintaining the cylinder pressure at 140 p.s.i.
A kick-back sample was taken at the end of the pressure period but before starting the steaming by momentarily reducing the pressure slightly. The pH of this kick-back sample was 3.85.
The gross absorption of preservative during the pressure period was 29.29 lbs/cu.ft.
The sample was steamed at 212° F. for three hours while maintaining 140 p.s.i. pressure on the cylinder.
A kick-back sample taken at the end of the steaming cycle had a pH of 5.45.
The sample was exposed to a 26" Hg. vacuum for one hour before being removed and weighed to determine net solution retention.
A sample of the drip obtained during the final vacuum had a pH of 5.50.
The net solution retention obtained during treatment was 9.09 lbs/cu.ft. so that the gross absorption was reduced by over 20 lbs/cu.ft.
A disc obtained from the middle of this sample after treatment was dried in an oven to determine its average moisture content. Its moisture content expressed as a percent of oven-dry weight was 40.3%.
Analysis of the samples obtained during the treatment of this sample for Cu and Cr gave the results indicated in the table below. In this table, Sample 1 was the original treatment solution; Sample 2 was the kick-back after impregnation but before steaming; Sample 3 was the kick-back after impregnation and steaming; and Sample 4 was the drip from the wood during final vacuum.
______________________________________
% Reduction % Reduction Sample pH % CuO of CuO % CrO 3 of CrO 3
______________________________________
1 3.40 0.717 -- 1.661 --
2 3.85 0.628 12.41 1.527 8.07
3 5.45 0.014 98.06 0.027 98.37
4 5.50 0.025 96.58 0.009 99.46
______________________________________
The disc obtained from this sample after treatment and steaming indicated complete penetration by the preservative.
EXAMPLE 3
In this example, the wood was given a pretreatment with Ba(OH) 2 prior to treatment with CCA to determine if the sugars could be precipitated in the wood so that they would not contaminate the kick-back.
A piece of kiln-dry Southern pine (20% mositure content) 51/2" in diameter and 18" long was impregnated as follows:
A. Ba(OH) 2 Solution:
A 0.50% of Ba(OH) 2 (anhydrous) solution was prepared from a 1.00% solution by dilution with water.
B. Ba(OH) 2 Impregnation Cycle:
20 p.s.i. initial air pressure was established and held for five minutes. The treatment vessel was charged with the Ba(OH) 2 solution and a pressure of 120 p.s.i. was established and held for two hours.
Excess Ba(OH) 2 solution was drained from the vessel while maintaining cylinder pressure at 120 p.s.i.
A kick-back sample was taken by momentarily reducing the pressure slightly at the end of the pressure period but before starting the steaming cycle. The pH of this kick-back sample was 12.4.
The gross absorption of the Ba(OH) 2 solution during the pressure period was 31.24 lbs/cu.ft.
The sample was steamed at 212° F. for three hours while maintaining 120 psi pressure on the cylinder.
A kick-back sample was taken at the end of the steaming cycle. The pH of this sample was 6.1.
The sample was exposed to a 26" Hg. vacuum for one hour before being removed and weighed to determine net solution retention.
The net solution retention obtained during treatment was 2.50 lbs/cu.ft.
The sample was replaced in the cylinder immediately following the above weighing and given an empty-cell treatment in accordance with this invention with a 2% (oxide basis) solution of CCA as follows:
C. CCA Impregnation Cycle:
20 p.s.i. initial air pressure was established and held for five minutes. The treatment vessel was charged with the CCA solution and a pressure of 120 p.s.i. was established and held for two hours.
Excess CCA solution drained from the vessel while maintaining cylinder pressure at 120 p.s.i.
A kick-back sample was taken at the end of the pressure period but before starting the steaming cycle by momentarily reducing the pressure slightly. The pH of this kick-back sample was 2.3.
The gross absorption of the CCA solution during the pressure period was 26.48 lbs/cu.ft.
The sample was steamed at 212° F. for three hours while maintaining 120 p.s.i. pressure on the cylinder.
A kick-back sample was taken at the end of the steaming cycle. The pH of this sample was 4.0.
The sample was exposed to a 26" Hg. vacuum for one hour before being removed and weighed to determine net retention of CCA solution.
The net CCA solution retention was 3.24 lbs/cu.ft., with the total gain in weight during both impregnation cycles being 9.45 lbs/cu.ft.
The sample was sawed at midlength to determine the depth of penetration of the CCA solution. The entire cross section was penetrated.
Analysis of the kick-back samples obtained during the CCA impregnation cycle gave the following results. In the table, Sample 1 was the original treatment solution; Sample 2 was the kick-back after impregnation; and Sample 3 was the kick-back after steaming.
______________________________________
% Reduction of: Sample pH CuO CrO 3 As 2 O 5 CuO CrO 3 As 2 O 5
______________________________________
1 1.6 0.329 0.916 0.689 -- -- --
2 2.3 0.163 0.604 0.428 50.46 34.06 37.88
3 4.0 0.000 0.002 0.003 100.00
99.56 99.56
______________________________________
Enough CCA concentrate was added to a portion of Sample 3 to bring its concentration up to 2.0% (oxide basis) to determine if the Cu, Cr and As would remain in solution. No precipitate occurred in this sample after two weeks' storage in the laboratory, indicating that the wood sugars were precipitated in the wood and did not, to any observable extent, contaminate the kick-back.
EXAMPLES 4-6
In Examples 4 through 6, samples of Southern pine wood were treated with CCA salts under varying process conditions, as shown in the following table. In this table, the column headed "Initial p.s.i." indicates the pressure to which the wood was exposed prior to impregnation. The column headed "Impregnation p.s.i." indicates the pressure that was established within the treatment vessel after the vessel had been filled with the treatment liquid. The "Steaming Temperature" was the ultimate temperature reached, over a period of about an hour, after the impregnation pressure was imposed. The "Holding Time" is the period of time that the vessel was maintained at the impregnation pressure and the steaming temperature.
The other columns indicate the percentage of the active ingredients in the initial treatment solution, the kick-back, and the percentage of the active ingredients that were retained within the wood. Note that in Examples 4 and 5 where the temperature of the treatment vessel was not increased above ambient, the deposition of the CCA salts did not begin to approach completion even after a holding time of as long as six hours. In contrast to this, Example 6 shows that at a steaming temperature of 210° F., well over 95% of the CCA salts were deposited in the wood after a holding time of only two hours.
________________________________________________________ __________________
TREATMENT RETAINED Ini- Impreg- Steam- Hold- SOLUTION KICK-BACK SALTS Ex- tial nation ing ing % % % % % % % % ample psi psi Temp. Time CuO CrO 3 As 2 O 5 CuO As 2 O 5 CuO CrO 3 As 2 O 5
________________________________________________________ __________________
4 10 100 None
3 hrs.
0.382
1.010
0.718
0.139
0.425
0.070
63.6
57.9
90.3
5 10 110 None
6 hrs.
0.331
0.962
0.692
0.096
0.338
0.170
71.1
64.8
75.5
6 10 120 210° F.
2 hrs.
0.314
0.904
0.819
0.011
0.006
0.017
96.5
99.3
97.9
________________________________________________________ __________________
EXAMPLE 7
A charge of air-dried (25% moisture) pine fence posts about 4"×8'6" in size were placed in a pressure vessel and an initial air pressure of 20 psi was introduced into the treatment vessel and held for about five minutes. The vessel was then filled with a CCA solution (see Table 1) without relieving the initial pressure, and the pressure was increased to 140 psi over a period of about 55 minutes. The temperature of the CCA impregnating solution was about 90° F. and the gross absorption achieved was 31.4 lb/cu.ft.
When the required gross absorption had been obtained steam was admitted to the coils in the cylinder and the CCA solution in the cylinder was heated to 200° F. within 30 minutes and this temperature was maintained for 60 minutes. No precipitation of CCA salts from the treatment solution was noted during this heating cycle.
At the end of the heating period, the CCA solution was removed from the cylinder without permitting the pressure on the system to change, following which the pressure on the system was released to collect the kickback separate from the CCA solution. The temperature of the kickback solution was 180° F. A final vacuum of 60 minutes at 25 in. Hg. followed after releasing the pressure on the system.
The wood was removed from the cylinder and weighed. It was determined that the net preservative solution retention was 7 lb/cu.ft.
Results of anaylses performed on the CCA before treatment, after treatment and heating and on a sample of the kickback after heating are contained in Table 1:
TABLE 1
______________________________________
Metal Content (% oxide basis) Solution pH CuO CrO 3 As 2 O 5 Total Salt
______________________________________
CCA before treatment
1.92 0.304 0.870 0.643 1.817
CCA after treatment
2.03 substantially the same as above
and heating
Kickback 4.18 0.008 0.017 0.022 0.047
______________________________________
An increment core was taken from midlength of each post for analysis for Cu, Cr and As retention after treatment. The cores were cut into 1/2" segments and similar segments were combined for analysis. Results for these analyses are contained in Table 2:
TABLE 2
______________________________________
Retention of Metals - lb/cu.ft. Depth from (Oxide Basis) Surface (inches) CuO CrO 3 As 2 O 5 Total Salt
______________________________________
0.0 to 0.5 0.161 0.352 0.251 0.765
0.5 to 1.0 0.123 0.244 0.019 0.385
1.0 to 1.5 0.074 0.177 0.014 0.265
______________________________________
The times, pressures and temperatures utilized in the above-described modified empty-cell process may vary substantially, depending upon the species of wood being treated and the nature of the treatment liquid. Also, the treatment times are temperature-dependent since the desired reactions generally take place faster at higher temperatures. By way of example, representative data has been obtained in treating Southern pine with CCA salts and it was found that temperatures ranging from about 150° F. to 250° F. are useful. At temperatures lower than these, the reaction rates are inconveniently slow, and at higher temperatures, damage may be done to the wood. A preferred temperature range for treating Southern pine with CCA salts is from about 180° F. to 240° F. and, more preferably still, from about 200° F. to 230° F.
Treatment times will vary considerably and, depending on the temperature used in the treatment cycle, satisfactory results have been obtained using treatment times of from about one to about seven hours. Longer times can, of course, be used, but in the interest of productivity of the process, no purpose is served in prolonging the treatment time after the desired reactions have neared or reached completion.
The modified empty-cell process of this invention has been described primarily with regard to the impregnation of wood with CCA salts, but it can readily be understood by those of ordinary skill in the wood treatment arts that the invention is of utility in treating wood with other wood preservatives such as, for example, pentachlorophenol. Further, the water-borne materials may include such things as wood-softening agents, antichecking agents, film-formers, coloring agents, flame retardants, antistatic agents, dimensional stabilizers, and other wood-treating agents. The process of this invention may also be used to leach materials, such as sugars, from wood, or, conversely, to precipitate sugars in the wood prior to a subsequent preservation step. The pH of the treatment liquid can be adjusted to maximize solubilization of the sugars and, if it is the object to fix the sugars in the wood, cations, such as barium or copper, may be included in the treatment liquid to form insoluble products with the sugars.
The modified empty-cell process of this invention makes it possible to conduct a plurality of sequential impregnations without the intervening drying or curing steps required in the full-cell process. For example, substantially immediately after wood is treated with CCA salts in accordance with this invention, it may be impregnated with oil-based preservatives. Another example would be to impregnate with preservative inorganic salts followed by a subsequent treatment with pentachlorophenol. This increases the degree of protection for the wood and is advantageous if aresenic salts must be excluded from the treatment liquid because of environmental hazards.
胖虎找的是不是怎么作压缩木呀:$
摆渡"压缩木工艺"
压缩木生产全套工艺流程
http://www.wood365.cn/know/knowledgeDisplay_101.html
水蒸气处理法制作压缩整形木的研究(Ⅱ)──物理力学特性和工艺性
这个是CNKI上的,摆渡可以找到免费帐号密码的;P
http://www.cnki.com.cn/Article/CJFD2000-DBLY200004003.htm
摆渡"压缩木工艺"
压缩木生产全套工艺流程
http://www.wood365.cn/know/knowledgeDisplay_101.html
水蒸气处理法制作压缩整形木的研究(Ⅱ)──物理力学特性和工艺性
这个是CNKI上的,摆渡可以找到免费帐号密码的;P
http://www.cnki.com.cn/Article/CJFD2000-DBLY200004003.htm
我早就回了不能自然吸水，只能靠压力。水蒸气是不能往木头里注水的。:$ :$
请联系痴痴滴小木头:b
[:a4:] [:a4:] [:a4:] 痴痴滴小木头MM呢?
看来都是专业技术问题
本来以为可以考虑一下 烘干木材 然后加湿的
看样子不行
本来以为可以考虑一下 烘干木材 然后加湿的
看样子不行
你要吸水干吗？？？？？？