Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B27—WORKING OR PRESERVING WOOD OR SIMILAR MATERIAL; NAILING OR STAPLING MACHINES IN GENERAL
  • B27K—PROCESSES, APPARATUS OR SELECTION OF SUBSTANCES FOR IMPREGNATING, STAINING, DYEING, BLEACHING OF WOOD OR SIMILAR MATERIALS, OR TREATING OF WOOD OR SIMILAR MATERIALS WITH PERMEANT LIQUIDS, NOT OTHERWISE PROVIDED FOR; CHEMICAL OR PHYSICAL TREATMENT OF CORK, CANE, REED, STRAW OR SIMILAR MATERIALS
  • B27K3/00—Impregnating wood, e.g. impregnation pretreatment, for example puncturing; Wood impregnation aids not directly involved in the impregnation process
  • B27K3/16—Inorganic impregnating agents
  • B27K3/22—Compounds of zinc or copper
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B27—WORKING OR PRESERVING WOOD OR SIMILAR MATERIAL; NAILING OR STAPLING MACHINES IN GENERAL
  • B27K—PROCESSES, APPARATUS OR SELECTION OF SUBSTANCES FOR IMPREGNATING, STAINING, DYEING, BLEACHING OF WOOD OR SIMILAR MATERIALS, OR TREATING OF WOOD OR SIMILAR MATERIALS WITH PERMEANT LIQUIDS, NOT OTHERWISE PROVIDED FOR; CHEMICAL OR PHYSICAL TREATMENT OF CORK, CANE, REED, STRAW OR SIMILAR MATERIALS
  • B27K3/00—Impregnating wood, e.g. impregnation pretreatment, for example puncturing; Wood impregnation aids not directly involved in the impregnation process
  • B27K3/02—Processes; Apparatus
  • B27K3/15—Impregnating involving polymerisation including use of polymer-containing impregnating agents
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B27—WORKING OR PRESERVING WOOD OR SIMILAR MATERIAL; NAILING OR STAPLING MACHINES IN GENERAL
  • B27K—PROCESSES, APPARATUS OR SELECTION OF SUBSTANCES FOR IMPREGNATING, STAINING, DYEING, BLEACHING OF WOOD OR SIMILAR MATERIALS, OR TREATING OF WOOD OR SIMILAR MATERIALS WITH PERMEANT LIQUIDS, NOT OTHERWISE PROVIDED FOR; CHEMICAL OR PHYSICAL TREATMENT OF CORK, CANE, REED, STRAW OR SIMILAR MATERIALS
  • B27K3/00—Impregnating wood, e.g. impregnation pretreatment, for example puncturing; Wood impregnation aids not directly involved in the impregnation process
  • B27K3/16—Inorganic impregnating agents
  • B27K3/26—Compounds of iron, aluminium, or chromium
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B27—WORKING OR PRESERVING WOOD OR SIMILAR MATERIAL; NAILING OR STAPLING MACHINES IN GENERAL
  • B27K—PROCESSES, APPARATUS OR SELECTION OF SUBSTANCES FOR IMPREGNATING, STAINING, DYEING, BLEACHING OF WOOD OR SIMILAR MATERIALS, OR TREATING OF WOOD OR SIMILAR MATERIALS WITH PERMEANT LIQUIDS, NOT OTHERWISE PROVIDED FOR; CHEMICAL OR PHYSICAL TREATMENT OF CORK, CANE, REED, STRAW OR SIMILAR MATERIALS
  • B27K3/00—Impregnating wood, e.g. impregnation pretreatment, for example puncturing; Wood impregnation aids not directly involved in the impregnation process
  • B27K3/16—Inorganic impregnating agents
  • B27K3/28—Compounds of arsenic or antimony
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B27—WORKING OR PRESERVING WOOD OR SIMILAR MATERIAL; NAILING OR STAPLING MACHINES IN GENERAL
  • B27K—PROCESSES, APPARATUS OR SELECTION OF SUBSTANCES FOR IMPREGNATING, STAINING, DYEING, BLEACHING OF WOOD OR SIMILAR MATERIALS, OR TREATING OF WOOD OR SIMILAR MATERIALS WITH PERMEANT LIQUIDS, NOT OTHERWISE PROVIDED FOR; CHEMICAL OR PHYSICAL TREATMENT OF CORK, CANE, REED, STRAW OR SIMILAR MATERIALS
  • B27K5/00—Treating of wood not provided for in groups B27K1/00, B27K3/00
  • B27K5/06—Softening or hardening of wood
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L97/00—Compositions of lignin-containing materials
  • C08L97/02—Lignocellulosic material, e.g. wood, straw or bagasse
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L33/00—Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides or nitriles thereof; Compositions of derivatives of such polymers
  • C08L33/04—Homopolymers or copolymers of esters
  • C08L33/14—Homopolymers or copolymers of esters of esters containing halogen, nitrogen, sulfur, or oxygen atoms in addition to the carboxy oxygen
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L71/00—Compositions of polyethers obtained by reactions forming an ether link in the main chain; Compositions of derivatives of such polymers
  • C08L71/02—Polyalkylene oxides

Definitions

• the invention consists in treating wood to permanently reduce its hardness. More particularly, the present invention relates to a treatment for providing a permanent decrease of the hardness of wood, and an increased moisture content at equilibrium by in situ polymerization of prepolymers therein. The invention is also directed to articles of wood which are impregnated with polymeric networks providing a permanent reduction of their hardness, and an increased moisture content at equilibrium, (b) Description of Prior Art
• CC copper-chromium
• CCA copper-chromium-arsenate
• CCB copper-chromium-boron
• CFK copper- chromium-fluoride
• CCFB copper-chromium-fluoroborate
• CCP copper-chromium-phosphorous
• Other waterborne preservatives exist that include copper or chromium.
• a CCA type C solution normally contains 19% CuO, between 16 and 45% AS2O5 and between 36 and 65% Cr ⁇ 3.
• additives include polyethylene glycol (PEG 1000), marketed under the trade designation CCA-PEG, and polyethylene glycol of higher molecular weight (PEG 8000), marketed under the trade designation
• CCA-PEG + Another additive is a wax which makes wood impermeable and which has been marketed under the trade designation CCA- ULTRAWOOD®.
• CCA-ETTM an additive based on a formulation containing an oil emulsion in water is sold under the trade designation CCA-ETTM.
• the posts are introduced into an autoclave in which a vacuum (e.g. 636 mm Hg) is applied to remove the air contained in wood cells.
• a vacuum e.g. 636 mm Hg
• the treating solution of CCA at 2% is introduced into the autoclave and a maximum pressure of for example 1040 kPa is applied so as to enable the penetration of the preservative into wood. This pressure is maintained for about 5 hours for red pine and the solution is thereafter flushed away.
• CCA is then fixed to the wood at a temperature of for example 60°C for a few hours.
• Japanese Laid-Open Application 1196302 published August 8, 1989 discloses a method wherein a woody material is impregnated with an aqueous solution of water soluble and radically polymerizable compounds, water soluble and radically polymerizable metal salts of organic acids and possibly water soluble salts of inorganic acids.
• the radically polymerizable compounds may be glycerin di(meth)acrylate, trimethylolpropane tri(meth)acrylate, polyethylene glycol mono(meth)acrylate or polyethylene glycol di(meth)acrylate.
• the water soluble and radically polymerizable metal salts are preferably acrylates of Zn, Ba, Ca, Mg or Al. Wood thus treated has good durability, flame resistance, hardness, dimensional stability, rot resistance and insect resistance. This document however does not disclose a specific hardness which is maintained during the entire life of a pole.
• Wood material thus treated has improved durability and dimensional stability at a low impregnation degree.
• Japanese Patent 79012524 dated May 23, 1979 describes the manufacture of wood plastic composites using an ethylenically unsaturated monomer and a polymerization initiator, thereby preventing local heating and excess buildup.
• This patent is mute with respect to the hardness of a wood treated by that process, and is therefore not relevant to the subject matter ofthe present invention.
• U.S. Patent No. 4,567,115 issued January 28, 1986 describes treating wood with an aqueous solution containing water, hexavalent chromium, copper, arsenic and polyethylene glycol 1000.
• the polyethylene glycol 1000 introduced into the wood treated by this process is easily washed away so that the reduced hardness obtained is not permanent.
• Japanese Laid-Open Application 9160645 published March 26, 1991 discloses the preparation of resin-impregnated wood for exterior walls by immersing wood in a polymerizable resin solution including a pyrolignous acid as a preservative. Contrary to the teaching ofthe present invention, the material obtained is hard (high strength) and does not undergo a permanent reduced hardness.
• Canadian Patent No. 907,232 issued August 8, 1972 relates to the preservation of wood using a monomeric or polymeric methylacrylate which is used in association with a preservative, in order to prolong the service life of wood products, and has nothing to do with the reduction of wood hardness.
• Canadian Patent No. 866,158 issued March 16, 1971 describes a method of manufacturing hard, synthetic polymer-containing wood wherein wood is impregnated with a mixture of a monomer, an additional polymer and a free radical catalyst.
• the method gives a hard product contrary to the aim ofthe present invention, which instead intends to reduce its hardness.
• U.S. Patent No. 4,205,097 issued May 27, 1980 relates to a process for producing an impregnated article by impregnating it with a polymerizable solution followed by heat treatment, so as to give a product which needs no after-treatment. Again this treatment has nothing to do with reduced hardness ofthe product obtained.
• Swedish Patent 9002302 issued June 29, 1990 relates to a wood treatment with a multi functional allyl ether, a (meth)acrylate terminated polyether and/or urethane prepolymer to provide a wood which is dimensionally stable.
• This invention is of course totally unrelated to the aim of the present invention which intends at permanently reducing the hardness of wood.
• Japanese Laid-Open Application 4259506 published September 16, 1992 discloses the use of a dicarboxylic anhydride with a methacrylate to impregnate wood in order to give it high dimensional stability and weather resistance.
• the same comments apply as those made with respect to Swedish Patent 9002302.
• Other references of interest include French Application 2,661,685 published November 8, 1991, Canadian Application No. 2,041,561 published November 2, 1991 and French Application 2,278,708 published February 13, 1978.
• a treatment for wood which includes the steps of (a) providing articles of wood, (b) introducing these articles of wood into an autoclave under conditions to substantially remove the air contained therein, (c) introducing into the autoclave a solution optionally containing a wood preservative, and impregnating the articles of wood with the solution, and (d) submitting the articles of wood which have been impregnated to a temperature higher than ambient for fixation of the optionally present preservatives.
• the treatment is characterized in that the solution optionally containing the wood preservatives also contains at least one water soluble prepolymer of low molecular weight ( ⁇ 10,000) having reactive groups which can be specifically localized at the end of the main or lateral chains, or statistically or block distributed in the main chain, in order to ensure a multi- dimensional cross-linking in the wood in the presence of the solution optionally containing the wood preservatives.
• the method may comprise adding the wood preservative into the treatment solution, and impregnating the articles of wood with the wood preservative during step (c), or it may comprise impregnating the wood preservatives into the wood articles before introducing them into the treatment solution, the latter then being substantially free of wood preservative.
• the method may also comprise treating articles of wood only with the prepolymer without using a wood preservative.
• the reactive groups enabling cross-linking may be selected from the allyl, vinyl, acrylate or methacrylate or issued from compounds having at least one reactive double bond.
• the solution also contains a polymerization initiator.
• the solution could optionally contain a crosslinking agent to increase the efficiency of the crosslinking reaction.
• the crosslinking agent could be selected from the group consisting of trimethylolpropane trimethacrylate, trimethylolpropane triacrylate, glycerol trimethacrylate and glycerol triacrylate.
• Step (d) is characterized in that it is carried out in a gaseous atmosphere which may be substantially free of oxygen or which may comprise air under conditions to allow for the polymerization of the prepolymers.
• the treatment enables to reduce the hardness of the wood and to increase the moisture content of the wood at equilibrium while ensuring reduced hardness and increased moisture content to be maintained during aging of the wood outside under leaching conditions, substantially at the same level as immediately following the treatment.
• the wood preservatives are based on hydrosoluble formulations.
• Step (b) is normally carried out under a vacuum of about 600 mm Hg, preferably under a vacuum of 636 mm Hg.
• Step (c) consists of introducing the solution that contains preferably about 2% w/v of chromated copper arsenate into the autoclave at a pressure of about 1000-1040 kPa, preferably 1040 kPa, so as to facilitate penetration of the preservative into wood.
• the solution contains about 4 to 10% w/v of prepolymer and up to about 5 weight percent of polymerization initiator with respect to the prepolymer.
• Step (d) is normally carried out at a temperature between about 25 and 100°C for a period of time, preferably for about 2.5 to 48 hours, that allows for a substantial fixation of all the optionally present wood preservative components in the wood and for polymerization of the prepolymers in the wood.
• the prepolymer which may be used may be selected from the following: i) copolymer of formula:
• A is a homopolymer or copolymer of ethylene oxide or derivatives thereof, and B' is an acrylate group ofthe formula:
• R is H or CH3.
• the most suitable prepolymer is a polyethylene glycol diacrylate or dimethacrylate, commercially available from Polysciences in a plurality of molecular weights; ii) copolymer of formula:
• Z is a residue of a compound having at least one active hydrogen
• k is a whole number between 1 and 6
• m is a number equal to 0 or whole number not less than 1
• n is a number equal to 0 or whole number not less than 1
• B" is an alkyl group, an acyl group or a group having at least one reactive double bound
• R is an allyl group, an alkenyl group or a group of formula:
• R is an alkyl or alkenyl group and Re is a segment of formula
• compositions are those wherein Z is a residue of glycerin or trimethylolpropane and k is a number equal to 3, or Z is a residue of ethylene glycol and k is a number equal to 2; iii) copolymer of type:
• A represents a segment derived from homopolymers or copolymers of ethylene oxide or derivatives thereof
• B represents segments comprising radicals having at least one double bond (for example derivatives of alkynes, styrene or dimethylfuran).
• A is a POE or a copolymer POE/POP and B' " is a vinyl group:
• R is R a , wherein R a is an alkyl, alkenyl or alkynyl having 1 to 12 carbon atoms or -CH2-0-Re-Ra wherein Ra is defined above, R e is a polyether of the formula -(CH2CH2-0)p, wherein p is an integer from 0 to 10, or a cyclic ether wherein the ring has more than 3 carbon atoms.
• the invention also relates to wood articles impregnated, preferably at a depth which corresponds to at least a given portion of the sapwood as required for the preservative itself, by the American Wood Preservers'
• AWPA American Standards Association
• CSA Canadian Standards Association
• red pine blocks 40 cm long by 8 cm wide were treated under conditions similar to those used in the industry.
• a solution is prepared according to the norms which are used in the industry by optionally adding to a volume of water a given amount of an inorganic preservative so as to obtain a concentration of 2% w/v of the said optionally present wood preservative.
• To this solution there was included a variable quantity (4 to 10% w/v) of prepolymer and a quantity of polymerization initiator equal to 5% of he weight ofthe prepolymer.
• fixation-polymerization The treatment under pressure was carried out in a stainless steel autoclave having a diameter of 25 cm and a length of 80 cm. Fixation of the optionally present inorganic preservative and polymerization are carried out during the same step called fixation-polymerization. This step is carried out at 95°C in an atmosphere substantially free of oxygen for a period of 2.5 to 16 hours, depending on the dimensions of the block of red pine. The chosen temperature is dependent on the choice of the polymerization initiator. Five water soluble polymerization initiators having activation temperatures (t ⁇ / 2 of 44°C, 56°C, 61°C, 69°C and 86°C) respectively #1 to #5, were tested with substantially the same results. These polymerization initiators (commercially available from Wako Pure Chemical Industries Ltd.) are respectfully the following: 1) 2,2'azobis[2-(2-imidazolin-2-yl) propane]- dihydro chloride
• initiators that can be used include an oxidizing agent such as potassium sulfate.
• a plurality of prepolymers have been used, e.g. polyethylene glycol diacrylates (PEGDA) and polyethylene glycol dimethacrylate (PEGDM), in which the average molecular weight varied between 200 and 1000, glycerol tri[poly(oxyethylene) (oxypropylene) monoacrylate] tri-(OE-OP-MA) having a molecular weight of 8000 and copolymer of ethylene oxide — butylene oxide — allyl glycidyl ether (OE-OB-AGE) having a molecular weight of 5000.
• PEGDA polyethylene glycol diacrylates
• PEGDM polyethylene glycol dimethacrylate
• OE-OP-MA glycerol tri[poly(oxyethylene) (oxypropylene) monoacrylate] tri-(OE-OP-
• All these prepolymers are soluble in an aqueous medium.
• the fixation-polymerization step enables to produce a tridimensional network which makes the polymers insoluble. Therefore, it is believed that the polymer fills the cavities of the wood structure. Because the resulting polymers form a network and are insoluble, their molecular weights cannot be characterized.
• the concentration of polymer in the wood after impregnation represents an average over the treated portion of the wood block and is evaluated by quantifying the prepolymer extracted from the wood before and after the polymerization takes place.
• the blocks of wood are oven-dried to decrease their moisture content to a value around 30%, as it is normally done in the industry.
• An additional oven-drying is carried out to reduce the moisture content between 15 and 20%, in order to be close to the moisture contents found in similar posts which are in service, for comparison purposes.
• the moisture content of the blocks was measured in the first two centimeters of depth, because it may influence the hardness of the wood.
• the moisture contents measured and the corresponding standard deviation illustrate that the range of values is sufficiently restricted for these data to be compared with one another.
• the blocks for each treatment that includes a polymer have been separated into two groups, a group stuck as such and another one aged then stuck. Accelerated aging of the blocks in the laboratory enables to simulate an aging as established by comparison with CCA PEG 1000 treated poles that have been in service for a few years, in order to evaluate the permanence of the effect of the polymer additive in wood. It consists in an alternation of periods of spraying with demineralized water and periods of drying.
• the treatment may be carried in the presence of air or oxygen.
• the wood preservative may include at least one reactive group enabling its introduction in the polymer matrix at the cross-linking step.
• the wood preservative is chemically fixed in the prepolymer.
• the wood preservative is solubilized in water using a surfactant material.
• a vacuum of 636 mm Hg is applied to remove the air contained in the wood cells.
• a 50-L volume of solution A is obtained by diluting 2 L of a 50 %w/v solution of chromium copper arsenate (CCA) with water.
• a solution B is obtained by adding 1936.1 g of polyethylene oxide dimethacrylate of molecular weight 600 and 101.34 g of 2,2'- azobis[2-methyl-N-(2-hydroxyethyl)-propionamide] to the 50-L volume of solution A.
• a portion of solution B is introduced into the autoclave at a maximum pressure of 1040 kPa. The pressure is maintained for 5 hours and the solution is thereafter flushed away.
• the polymerization is done in the autoclave under an inert atmosphere at 95 °C during 6 hours, leading to an
• EXAMPLE 2 In an autoclave, we introduced three wood blocks of 40 cm long by 8 cm wide obtained from a CCA-treated red pine pole. A vacuum of 636 mm Hg is applied to remove the air contained in the wood cells. A 50-L volume of solution A is obtained by adding 2017.3 g of polyethylene oxide dimethacrylate of molecular weight 600 and 96.42 g of 2,2'-azobis[2- methyl-N-(2-hydroxyethyl)-propionamide] to 50 L of water. A portion of solution A is introduced into the autoclave at a maximum pressure of
• the wood blocks are oven-dried to an average moisture content of 18.7 ⁇ 0.8 % in the 0-2 cm depth. Their resistance to gaff penetration at 23 °C is lower than that of wood treated with CCA only, see Table 1.
• EXAMPLE 3 In an autoclave, we introduced three blocks of untreated red pine 40 cm long by 8 cm wide. A vacuum of 636 mm Hg is applied to remove the air contained in the wood cells. A 50-L volume of solution A is obtained by adding 2103.4 g of polyethylene oxide dimethacrylate of molecular weight 600 and 99,72 g of 2,2'-azobis[2-methyl-N-(2- hydroxyethyl)-propionamide] to 50 L of water. A portion of solution A is introduced into the autoclave at a maximum pressure of 1040 kPa. The pressure is maintained for 5 hours and the solution is thereafter flushed away. The polymerization is done in the autoclave under an inert atmosphere at 95 °C during 6 hours, leading to an average concentration of
• a solution A is obtained by adding 1037.3 g of Cr ⁇ 3 to 50 L of water.
• a solution B is obtained by adding 2046.8 g of polyethylene oxide dimethacrylate of molecular weight 600 and 103.47 g of
• the wood blocks are oven-dried to an average moisture content of 12.4 ⁇ 1.0% in the 0-2 cm depth. Their resistance to gaff penetration is lower than that of wood treated with CCA only, see
• a solution B is obtained by adding 1920.6 g of polyethylene oxide dimethacrylate molecular weight of 600 and 98.59 g of
• the wood blocks are oven-dried to an average moisture content of 19.6 ⁇ 1.7% in the 0-2 cm depth. Their resistance to gaff penetration is lower than that of wood treated with CCA only, see
• a solution A is obtained by adding 1022.1 g of ZnO to 50 L of water.
• a solution B is obtained by adding 2058.0 g of polyethylene oxide dimethacrylate of molecular weight 600 and 93.51 g of 2,2'-azobis[2- methyl-N-(2-hydroxyethyl)-propionamide] to the 50-L volume of solution A.
• a portion of solution B is introduced into the autoclave at a maximum pressure of 1040 kPa. The pressure is maintained for 5 hours and the solution is thereafter flushed away.
• the polymerization is done in the autoclave under an inert atmosphere at 95 °C during 6 hours, leading to an average concentration of PEGDM of 18.0 ⁇ 1.8 glv? in the treated portion of the wood blocks.
• a solution A is obtained by adding 1132.1 g of H3BO3 to 50 L of water.
• a solution B is obtained by adding 2004.7 g of polyethylene oxide dimethacrylate of molecular weight 600 and 98.68 g of
• the wood blocks are oven-dried to an average moisture content of 17.2 ⁇ 1.8% in the 0-2 cm depth. Their resistance to gaff penetration is lower than that of wood treated with CCA only, see Table 1.
• EXAMPLE 9 In an autoclave, we introduced three blocks of red pine of 40 cm long by 8 cm wide. A vacuum of 636 mm Hg is applied to remove the air contained in the wood cells. A solution A is obtained by adding 976.8 g of NaF to 50 L of water. A solution B is obtained by adding 2071.5 g of polyethylene oxide dimethacrylate of molecular weight 600 and 102.24 g of 2,2'-azobis[2-methyl-N-(2-hydroxyethyl)-propionamide] to the 50-L volume of solution A. A portion of solution B is introduced into the autoclave at a maximum pressure of 1040 kPa. The pressure is maintained for 5 hours and the solution is thereafter flushed away. The polymerization is done in the autoclave under an inert atmosphere at 95 °C during 6 hours, leading to an average concentration of PEGDM of 31.4 ⁇ 4.1 kg/m 3 in the treated portion of the wood blocks .
• the wood blocks are oven-dried to an average moisture content of 23.8 ⁇ 2.9% in the 0-2 cm depth. Their resistance to gaff penetration is lower than that of wood treated with CCA only, see
• a 50-L volume of solution A is obtained by diluting 2 L of a 50 %w/v solution of chromium copper arsenate (CCA) with water.
• a solution B is obtained by adding 2143.2 g of polyethylene oxide dimethacrylate of molecular weight 600 and 100.77 g of 2,2'- azobis[2-methyl-N-(2-hydroxyethyl)-propionamide] to the 50-L volume of solution A.
• a portion of solution B is introduced into the autoclave at a maximum pressure of 1040 kPa. The pressure is maintained for 5 hours and the solution is thereafter flushed away.
• the polymerization is done in the autoclave under an inert atmosphere at 95 °C during 6 hours, leading to an
• a 50-L volume of solution A is obtained by diluting 2 L of a 50 %w/v solution of chromium copper arsenate (CCA) with water.
• a solution B is obtained by adding 1936.1 g of polyethylene oxide dimethacrylate of molecular weight 600 and 101.34 g of 2,2'- azobis[2-methyl-N-(2-hydroxyethyl)-propionamide] to the 50-L volume of solution A.
• a portion of solution B is introduced into the autoclave at a maximum pressure of 1040 kPa. The pressure is maintained for 5 hours and the solution is thereafter flushed away.
• the polymerization is done in the autoclave under an inert atmosphere at 95 °C during 6 hours, leading to an
• a 50-L volume of solution A is obtained by diluting 2 L of a 50 %w/v solution of chromium copper arsenate (CCA) with water.
• a solution B is obtained by adding 2143.2 g of polyethylene oxide dimethacrylate of molecular weight 600 and 100.77 g of 2,2'- azobis[2-methyl-N-(2-hydroxyethyl)-propionamide] to the 50-L volume of solution A.
• a portion of solution B is introduced into the autoclave at a maximum pressure of 1040 kPa. The pressure is maintained for 5 hours and the solution is thereafter flushed away.
• the polymerization is done in the autoclave under an inert atmosphere at 95 °C during 6 hours, leading to an
• the wood blocks are oven-dried to an average moisture content of 17.4 + 1.5% in the 0-2 cm depth, and aged as described previously using alternations of water spraying and air-drying. Their resistance to gaff penetration at -35 °C is lower than that of wood treated with CCA only, see Table 1.
• EXAMPLE 13 In an autoclave, we introduced three blocks of red pine of 40 cm long by 8 cm wide. A vacuum of 636 mm Hg is applied to remove the air contained in the wood cells. A 50-L volume of solution A is obtained by diluting 2 L of a 50 %w/v solution of chromium copper arsenate (CCA) with water. A solution B is obtained by adding 5103.7 g of polyethylene oxide dimethacrylate of molecular weight 600 and 247.21 g of 2,2'- azobis[2-methyl-N-(2-hydroxyethyl)-propionamide] to the 50-L volume of solution A. A portion of solution B is introduced into the autoclave at a maximum pressure of 1040 kPa.
• CCA chromium copper arsenate
• the pressure is maintained for 5 hours and the solution is thereafter flushed away.
• the polymerization is done in the autoclave under an inert atmosphere at 95 C during 6 hours, leading to an average concentration of PEGDM of 47.5 ⁇ 4.6 kg/m 3 in the treated portion ofthe wood blocks.
• the wood blocks are oven-dried to an average moisture content of 18.2 ⁇ 2.1 % in the 0-2 cm depth. Their resistance to gaff penetration at 23 °C is lower than that of wood treated with CCA only, see Table 1.
• a 50-L volume of solution A is obtained by diluting 2 L of a 50 %w/v solution of chromium copper arsenate (CCA) with water.
• a solution B is obtained by adding 5052.5 g of polyethylene oxide dimethacrylate of molecular weight 600 and 254.34 g of 2,2'- azobis[2-methyl-N-(2-hydroxyethyl)-propionamide] to the 50-L volume of solution A.
• a portion of solution B is introduced into the autoclave at a maximum pressure of 1040 kPa. The pressure is maintained for 5 hours and the solution is thereafter flushed away.
• the polymerization is done in the autoclave under an inert atmosphere at 95 °C during 6 hours, leading to an
• the wood blocks are oven-dried to an average moisture content of 20.1 ⁇ 2.5% in the 0-2 cm depth, and aged as described previously using alternations of water spraying and air-drying. Their resistance to gaff penetration at 23 °C is lower than that of wood treated with CCA only, see Table 1.
• EXAMPLE 15 In an autoclave, we introduced three blocks of red pine of 40 cm long by 8 cm wide. A vacuum of 636 mm Hg is applied to remove the air contained in the wood cells. A 50-L volume of solution A is obtained by diluting 2 L of a 50 %w/v solution of chromium copper arsenate (CCA) with water. A solution B is obtained by adding 5103.7 g of polyethylene oxide dimethacrylate of molecular weight 600 and 247.21 g of 2,2'- azobis[2-methyl-N-(2-hydroxyethyl)-propionamide] to the 50-L volume of solution A. A portion of solution B is introduced into the autoclave at a maximum pressure of 1040 kPa. The pressure is maintained for 5 hours and the solution is thereafter flushed away. The polymerization is done in the autoclave under an inert atmosphere at 95 °C during 6 hours, leading to an
• the wood blocks are oven-dried to an average moisture content of 18.2 ⁇ 2.1% in the 0-2 cm depth. Their resistance to gaff penetration at -35 °C is lower than that of wood treated with CCA only, see Table 1.
• EXAMPLE 16 In an autoclave, we introduced three blocks of red pine of 40 cm long by 8 cm wide. A vacuum of 636 mm Hg is applied to remove the air contained in the wood cells. A 50-L volume of solution A is obtained by diluting 2 L of a 50 %w/v solution of chromium copper arsenate (CCA) with water. A solution B is obtained by adding 5052.5 g of polyethylene oxide dimethacrylate of molecular weight 600 and 254.34 g of 2,2'- azobis[2-methyl-N-(2-hydroxyethyl)-propionamide] to the 50-L volume of solution A. A portion of solution B is introduced into the autoclave at a maximum pressure of 1040 kPa.
• CCA chromium copper arsenate
• a vacuum of 636 mm Hg is applied to remove the air contained in the wood cells.
• a 50-L volume of solution A is obtained by diluting 2 L of a 50 %w/v solution of chromium copper arsenate (CCA) with water.
• a solution B is obtained by adding 2006.9 g of polyethylene oxide diacrylate of molecular weight 200 and 98.04 g of 2,2'-azobis[2- methyl-N-(2-hydroxyethyl)-propionamide] to the 50-L volume of solution
• a portion of solution B is introduced into the autoclave at a maximum pressure of 1040 kPa. The pressure is maintained for 5 hours and the solution is thereafter flushed away. The polymerization is done in the autoclave under an inert atmosphere at 95 °C during 6 hours, leading to an
• EXAMPLE 18 In an autoclave, we introduced three blocks of red pine of 40 cm long by 8 cm wide. A vacuum of 636 mm Hg is applied to remove the air contained in the wood cells. A 50-L volume of solution A is obtained by diluting 2 L of a 50 %w/v solution of chromium copper arsenate (CCA) with water. A solution B is obtained by adding 1807.3 g of polyethylene oxide diacrylate of molecular weight 200, 194.29 g of trimethylolpropane triacrylate (TMPTA) and 101.72 g of 2,2*-azobis[2-methyl-N-(2- hydroxyethyl)-propionamide] to the 50-L volume of solution A.
• CCA chromium copper arsenate
• a solution B is obtained by adding 1807.3 g of polyethylene oxide diacrylate of molecular weight 200, 194.29 g of trimethylolpropane triacrylate (TMPTA) and 101.72 g of 2,2*-azobis
• a portion of solution B is introduced into the autoclave at a maximum pressure of 1040 kPa. The pressure is maintained for 5 hours and the solution is thereafter flushed away.
• the polymerization is done in the autoclave under an inert atmosphere at 95 °C during 6 hours, leading to an average concentration of PEGDA of 12.1 ⁇ 1.0 kg/m 3 and of TMPTA of 2.4 ⁇ 0.3 kg/m 3 in the treated portion ofthe wood blocks.
• a 50-L volume of solution A is obtained by diluting 2 L of a 50 %w/v solution of chromium copper arsenate (CCA) with water.
• a solution B is obtained by adding 2073.2 g of polyethylene oxide diacrylate of molecular weight 200 and 97.18 g of 2,2'-azobis[2- methyl-N-(2-hydroxyethyl)-propionamide] to the 50-L volume of solution
• a portion of solution B is introduced into the autoclave at a maximum pressure of 1040 kPa. The pressure is maintained for 5 hours and the solution is thereafter flushed away. The polymerization is done in the autoclave under an inert atmosphere at 95 °C during 6 hours, leading to an
• a 50-L volume of solution A is obtained by diluting 2 L of a 50 %w/v solution of chromium copper arsenate (CCA) with water.
• a solution B is obtained by adding 1969.2 g of a copolymer of ethylene oxide — buthylene oxide — allyl glycidyl ether (OE-OB-AGE) having a molecular weight 5000 and 102.46 g of 2,2'-azobis[2-methyl-N-(2- hydroxyethyl)-propionamide] to the 50-L volume of solution A.
• a portion of solution B is introduced into the autoclave at a maximum pressure of 1040 kPa. The pressure is maintained for 5 hours and the solution is thereafter flushed away.
• the polymerization is done in the autoclave under an inert atmosphere at 95 °C during 6 hours, leading to an average concentration of OE-OB-AGE of 11.2 + 1.1 kg/m in the treated portion of the wood blocks. After the treatment, the wood blocks are oven-dried to an average moisture content of 16.4 ⁇ 2.1% in the 0-2 cm depth. Their resistance to gaff penetration at 23 °C is lower than that of wood treated with CCA only, see Table 1.
• a 50-L volume of solution A is obtained by diluting 2 L of a 50 %w/v solution of chromium copper arsenate (CCA) with water.
• a solution B is obtained by adding 4984.6 g of glycerol tri[poly(oxyethylene)(oxypropylene)monoacrylate] tri-(OE-OP-MA) having a molecular weight 8000 and 251.50 g of 2,2'-azobis[2-methyl-N-(2- hydroxyethyl)-propionamide] to the 50-L volume of solution A.
• a portion of solution B is introduced into the autoclave at a maximum pressure of 1040 kPa. The pressure is maintained for 5 hours and the solution is thereafter flushed away. The polymerization is done in the autoclave under an inert atmosphere at 95 °C during 6 hours, leading to an average
• EXAMPLE 22 In an autoclave, we introduced three blocks of red pine of 40 cm long by 8 cm wide. A vacuum of 636 mm Hg is applied to remove the air contained in the wood cells. A 50-L volume of solution A is obtained by diluting 2 L of a 50 %w/v solution of chromium copper arsenate (CCA) with water. A solution B is obtained by adding 2010.1 g of polyethylene oxide dimethacrylate of molecular weight 600 and 98.58 g of 2,2'azobis[2-
• the wood blocks are oven-dried to an average moisture content of 17.3 ⁇ 2.0% in the 0-2 cm depth. Their resistance to gaff penetration at 23 °C is lower than that of wood treated with CCA only, see Table 1.
• a 50-L volume of solution A is obtained by diluting 2 L of a 50 %w/v solution of chromium copper arsenate (CCA) with water.
• a solution B is obtained by adding 1994.3 g of polyethylene oxide dimethacrylate of molecular weight 600 and 100.39 g of azobis(2- amidinopropane)dihydro chloride to the 50-L volume of solution A.
• a portion of solution B is introduced into the autoclave at a maximum pressure of 1040 kPa. The pressure is maintained for 5 hours and the solution is thereafter flushed away.
• the polymerization is done in the autoclave under an inert atmosphere at 65 °C during 6 hours, leading to an
• the wood blocks are oven-dried to an average moisture content of 16.5 ⁇ 1.8% in the 0-2 cm depth. Their resistance to gaff penetration at 23 °C is lower than that of wood treated with CCA only, see Table 1.
• EXAMPLE 24 In an autoclave, we introduced three blocks of red pine of 40 cm long by 8 cm wide. A vacuum of 636 mm Hg is applied to remove the air contained in the wood cells. A 50-L volume of solution A is obtained by diluting 2 L of a 50 %w/v solution of chromium copper arsenate (CCA) with water.
• CCA chromium copper arsenate
• a solution B is obtained by adding 1532.1 g of polyethylene oxide dimethacrylate having a molecular weight of 600 and 3478.7 g of glycerol tri[poly(oxyethylene)(oxypropylene)monoacrylate] tri-(OE-OP- MA) having a molecular weight 8000 and 248.25 g of 2,2'-azobis[2-methyl- N-(2-hydroxyethyl)-propionamide] to the 50-L volume of solution A.
• a portion of solution B is introduced into the autoclave at a maximum pressure of 1040 kPa. The pressure is maintained for 5 hours and the solution is thereafter flushed away.
• the polymerization is done in the autoclave under an inert atmosphere at 95 °C during 6 hours, leading to an
• the wood blocks are oven-dried to an average moisture content of 19.0 ⁇ 1.6% in the 0-2 cm depth. Their resistance to gaff penetration at 23 °C is lower than that of wood treated with CCA only, see Table 1.

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