JPH11114914A - Method for producing wood-plastic composite and wood-plastic composite produced by the method - Google Patents

Abstract

(57) [Summary] [Problem] A wood-plastic composite that can efficiently produce a wood-plastic composite having excellent dimensional stability in a short time without using a large-scale device, and that does not require environmental measures. A method for producing a body and a wood-plastic composite produced by the method are provided. A cedar wood of 150 mm × 50 mm × 15 mm is heated to 90 ° C.
After boiling in water for 20 minutes, the cedar wood was converted to methyl-α- (hydroxymethyl) containing 0.5% AIBN.
By immersing in the acrylate solution for about 30 minutes, the AI
The cedar material is impregnated with methyl-α- (hydroxymethyl) acrylate together with BN, which is then wrapped in aluminum foil and heated at 80 ° C. for 2 hours by a drier, and then further dried for 10 hours.
By heating at 0 ° C for 1 hour, methyl-α
-Wood plastic composite was obtained by polymerizing (hydroxymethyl) acrylate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a wood-plastic composite in which wood is impregnated with a synthetic resin, and a wood-plastic composite produced by the method.

[0002]

2. Description of the Related Art Wood-plastic composites in which wood is impregnated with a synthetic resin have been known in the art, and are usually formed by a vacuum impregnation method, a pressure impregnation method or a vacuum impregnation method. The impregnated hydrophobic monomer is impregnated with the hydrophobic monomer in the interior of the dried wood, and then heated for a certain period of time to polymerize the impregnated hydrophobic monomer in the wood.

[0003] However, in order to impregnate wood with a hydrophobic monomer by the above-described reduced pressure / pressure impregnation method, pressure impregnation method or reduced pressure impregnation method, a huge apparatus capable of decompression operation and pressure operation is required. Therefore, it is disadvantageous in terms of equipment cost and installation space, and it requires a certain amount of time for decompression treatment and pressure treatment, so that it is not possible to efficiently impregnate synthetic resin monomers into wood in a short time. is there.

Further, as described above, since the monomer to be impregnated into wood is hydrophobic, it is difficult to sufficiently impregnate the monomer into the interior of the cell tissue of wood, and the dimensional stability of the manufactured wood-plastic composite is difficult. Has a problem,
In addition, since an organic solvent must be used as a diluent or a cleaning agent in a manufacturing process, there is a problem that environmental measures need to be taken.

Accordingly, an object of the present invention is to provide a wood-plastic composite having excellent dimensional stability efficiently in a short time without using a large-scale apparatus, and furthermore, there is no need for environmental measures. An object of the present invention is to provide a method for producing a plastic composite and a wood-plastic composite produced by the method.

[0006]

In order to solve the above-mentioned problems, the present invention comprises a step of boiling wood in water for a predetermined time, and immersing the wood boiled in water in a solution containing a hydrophilic vinyl monomer. Accordingly, an object of the present invention is to provide a method for producing a wood-plastic composite, comprising: a step of impregnating the wood with the hydrophilic vinyl monomer; and a step of polymerizing the hydrophilic monomer impregnated on the wood.

The hydrophilic vinyl monomers include methyl-α- (hydroxymethyl) acrylate and ethyl-
α- (hydroxymethyl) acrylate, propyl-α
-(Hydroxymethyl) acrylate, butyl-α-
(Hydroxymethyl) acrylate, t-butyl-α-
(Hydroxymethyl) acrylate, N-vinylpyrroline, acrylic acid, itaconic acid, dimethylaminoethyl methacrylate, acrylamide, 2-methoxyethyl acrylate, acryloyl morpholine and the like can be used, and in particular, methyl-α- ( (Hydroxymethyl) acrylate, ethyl-α- (hydroxymethyl)
A water-soluble vinyl monomer having a methylol group and a carboxylic acid ester such as acrylate, propyl-α- (hydroxymethyl) acrylate, butyl-α- (hydroxymethyl) acrylate, and t-butyl-α- (hydroxymethyl) acrylate is used. It is desirable.

[0008] Any of these hydrophilic vinyl monomers can be used alone, but after impregnating wood with a plurality of types of hydrophilic vinyl monomers, the plurality of types of hydrophilic vinyl monomers are added to the wood. By copolymerization, physical properties such as heat resistance, flexibility, and hardness can be improved.

Further, after impregnating wood with a plurality of types of hydrophilic vinyl monomers including polyfunctional hydrophilic vinyl monomers such as polyethylene glycol diacrylate, pentaerythritol diacrylate monostearate, and pentaerythritol triacrylate, By performing three-dimensional copolymerization of a plurality of types of hydrophilic vinyl monomers in the wood using the above hydrophilic vinyl monomer as a crosslinking agent, physical properties such as heat resistance can also be improved.

[0010] Further, by graft-polymerizing a hydrophilic vinyl monomer impregnated in wood and a cell tissue of wood using a polymerization initiator such as cerium ammonium nitrate, the cell tissue of wood and the impregnated monomer can be combined. When firmly bonded, phenomena such as whitening can be effectively prevented, and a wood-plastic composite having excellent weather resistance can be obtained.

Further, a wood plastic composite produced using a water-soluble vinyl monomer having a methylol group such as methyl-α- (hydroxymethyl) acrylate and a carboxylic acid ester is further heated at a high temperature of 100 ° C. or higher. By doing so, the lactone can be cyclized to improve physical properties such as heat resistance.

In the step of boiling wood, wood may be simply boiled in water, but a hydrophilic organic compound having a wood swelling function such as methanol, formamide, dimethylformamide, acetone, dioxane, dimethylsulfoxide and the like may be used. When the wood is boiled in an aqueous solution in which a solvent is mixed, the boiled wood can be impregnated with the monomer in a state of maximum swelling, so that the dimensional stability of the manufactured wood-plastic composite is further improved. .

As the monomer to be impregnated into wood, it is desirable to use the above-mentioned hydrophilic monomer, but if it is a small amount, it is also possible to use a hydrophobic monomer in combination.

Further, the combined use of a vacuum and pressure impregnation method or the like can further improve the monomer impregnation efficiency.

[0015]

Hereinafter, embodiments of the present invention will be described.
The present invention is not limited to these examples.

Example 1 After a cedar wood of 150 mm × 50 mm × 15 mm was boiled in water at 90 ° C. for 20 minutes, this cedar was used as a polymerization initiator in 0.5% azobisisobutyronitrile (hereinafter referred to as “polymerization initiator”). , AIBN).
about 30 in α- (hydroxymethyl) acrylate solution
The cedar was impregnated with methyl-α- (hydroxymethyl) acrylate together with AIBN by immersing for a minute. Thus, the water-soluble vinyl monomer methyl-α-
After the cedar material impregnated with (hydroxymethyl) acrylate is wrapped in aluminum foil and heated at 80 ° C. for 2 hours by a dryer, and further heated at 100 ° C. for 1 hour, methyl-α- (Hydroxymethyl) acrylate was polymerized to obtain a wood plastic composite. The reason for wrapping the cedar wood in aluminum foil during drying is that
This is for preventing methyl-α- (hydroxymethyl) acrylate impregnated in the cedar wood from volatilizing.

Example 2 A cedar wood of 150 mm × 50 mm × 15 mm was boiled in water at 90 ° C. for 20 minutes, and this cedar was used as a polymerization initiator in ethyl-α-containing 0.5% AIBN. By immersing in (hydroxymethyl) acrylate solution for about 30 minutes, ethyl-α together with AIBN
Cedar wood was impregnated with-(hydroxymethyl) acrylate. The cedar impregnated with the water-soluble vinyl monomer, ethyl-α- (hydroxymethyl) acrylate, was wrapped in aluminum foil and heated at 80 ° C. for 2 hours in a drier, and further heated at 100 ° C. for 1 hour. By heating for 0.5 hours, ethyl-α- (hydroxymethyl) acrylate was polymerized in the cedar wood to obtain a wood plastic composite.

(Example 3) An aqueous solution in which cedar wood of 150 mm x 50 mm x 15 mm is mixed with 70 parts by weight of water and 30 parts by weight of dimethyl sulfoxide which is a hydrophilic organic solvent having a wood swelling function. This cedar wood was boiled at 90 ° C for 20 minutes in a 0.5% AIB as a polymerization initiator.
Cedarwood was impregnated with butyl-α- (hydroxymethyl) acrylate together with AIBN by immersion in a butyl-α- (hydroxymethyl) acrylate solution containing N for about 30 minutes. The cedar material impregnated with butyl-α- (hydroxymethyl) acrylate, which is a water-soluble vinyl monomer, is wrapped in aluminum foil and heated at 80 ° C. for 2 hours in a drier, and further heated at 100 ° C. for 1 hour.
By heating for hours, butyl-α- (hydroxymethyl) acrylate was polymerized in the cedar wood to obtain a wood plastic composite.

Example 4 A cedar wood of 150 mm × 50 mm × 15 mm was boiled in water at 90 ° C. for 20 minutes, and then this cedar was used as a polymerization initiator containing 0.5% of AIBN.
Cedarwood was impregnated with t-butyl-α- (hydroxymethyl) acrylate together with AIBN by immersion in a -butyl-α- (hydroxymethyl) acrylate solution for about 30 minutes. The cedar material impregnated with the water-soluble vinyl monomer, t-butyl-α- (hydroxymethyl) acrylate, is wrapped in aluminum foil and heated at 80 ° C. for 2 hours in a drier, and then at 100 ° C. 1.
By heating for 5 hours, t-butyl-α- (hydroxymethyl) acrylate was polymerized to obtain a wood plastic composite.

Example 5 A cedar wood of 150 mm × 50 mm × 15 mm was boiled in water at 90 ° C. for 20 minutes, and this cedar was used as a polymerization initiator in methyl-containing 0.7% cerium ammonium nitrate. Cedarwood was impregnated with methyl-α- (hydroxymethyl) acrylate together with cerium ammonium nitrate by immersion in an α- (hydroxymethyl) acrylate solution for about 30 minutes. The cedar material impregnated with the water-soluble vinyl monomer, methyl-α- (hydroxymethyl) acrylate, was wrapped in aluminum foil and heated at 40 ° C. for 4 hours with a dryer,
Further, by heating at 100 ° C. for one hour, methyl-α- (hydroxymethyl) acrylate was graft-polymerized with the cell structure of the cedar material in the cedar material to obtain a wood-plastic composite.

Example 6 A cedar wood of 150 mm × 50 mm × 15 mm was boiled in water at 90 ° C. for 20 minutes, and then the cedar wood was mixed with 90 parts by weight of methyl-α- (hydroxymethyl) acrylate in polyethylene. A solution obtained by mixing 10 parts by weight of glycol diacrylate (0.1 g as a polymerization initiator).
Contains 5% AIBN. ) Was impregnated with methyl-α- (hydroxymethyl) acrylate and polyethylene glycol diacrylate together with AIBN into the cedar wood for about 30 minutes. The cedar material impregnated with the water-soluble vinyl monomer, methyl-α- (hydroxymethyl) acrylate, and the polyfunctional hydrophilic monomer, polyethylene glycol diacrylate, is wrapped in aluminum foil by a dryer. After heating at 80 ° C for 2 hours, and further heating at 100 ° C for 1.5 hours, methyl-α- (hydroxymethyl)
Acrylate and polyethylene glycol diacrylate were three-dimensionally copolymerized to obtain a wood plastic composite.

Example 7 The wood plastic composite produced in Example 3 was further heated at 180 ° C. for 2 hours to cyclize the lactone, and the glass transition point (Tg) of the polymer filled in the cedar wood was determined. A wood-plastic composite raised from 60 ° C to 115 ° C was obtained.

COMPARATIVE EXAMPLE In a state where a cedar material of 150 mm × 50 mm × 15 mm was immersed in a styrene monomer solution containing 0.5% of AIBN, the styrene monomer was removed together with AIBN under reduced pressure of about 5 mmHg for 2 hours. Cedar wood was impregnated. The cedar material impregnated with the styrene monomer, which is a hydrophobic monomer, is wrapped in aluminum foil and heated at 80 ° C. for 2 hours by a dryer, and then further heated to 100 ° C.
For 1.5 hours to polymerize the styrene monomer in the cedar wood to obtain a wood plastic composite.

The anti-swelling ability (ASE) of each of the wood-plastic composites of Examples and Comparative Examples obtained as described above was measured based on the following measuring method. The results are shown in Table 1. .

(Method of Measuring Anti-Swelling Ability) A state in which a wood-like treatment agent having a resin component filled therein and an untreated material having no resin component filled in wood are respectively immersed in a container filled with water at 25 ° C. After reducing the pressure to 1 mmHg for 1 hour, the pressure was returned to normal pressure, and these were allowed to stand in a submerged state. After 48 hours, the swelling ratios of the treating agent and the untreated material were measured, and ASE was calculated based on the equation shown in Formula I asked.

[0026]

(Equation 1)

[0027]

[Table 1]

As can be seen from Table 1, hydrophilic (water-soluble)
The wood plastic composites of Examples 1 to 7, in which the cedar material was impregnated with the vinyl monomer by the boiling impregnation method, were more resistant than the wood plastic composite material of the comparative example, in which the cedar material was impregnated with the hydrophobic monomer by the vacuum impregnation method. Very high swelling ability,
It can be said that the wood plastic composite produced by the production method of the present invention has excellent dimensional stability.

The reason for this is that the impregnation of the hydrophilic vinyl monomer in a state of being swollen in advance by boiling the wood results in a greater amount of monomer impregnation than in the conventional method. This is supported by the highest ASE of 73.67 in Example 3, in which cedar was boiled in an aqueous solution mixed with a hydrophilic organic solvent having a wood swelling ability.

Also, since the monomer to be impregnated into the wood is hydrophilic (water-soluble), it penetrates into the details of the wood structure and has high affinity with the cell wall of the wood. It is thought to have contributed to sex.

Further, as described above, in the comparative example employing the reduced pressure impregnation method, it takes about 2 hours to impregnate the monomer into the cedar wood, whereas in the first to fourth embodiments employing the boiling impregnation method. In No. 7, since the impregnation of the cedar material with the monomer is completed in about one hour, the time required for manufacturing the wood-plastic composite is greatly reduced, and the productivity of the wood-plastic composite is improved.

Further, in the boiling impregnation method employed in each of the embodiments, a boiling tank for boiling wood and a monomer storage tank for immersing the boiled wood in a hydrophilic vinyl monomer solution may be used. Unlike the pressure impregnation method, the pressure impregnation method, and the reduced pressure impregnation method, a large-sized device capable of performing a pressurizing operation and a depressurizing operation is not required, which is advantageous in terms of equipment cost and installation space.

Further, as a monomer for impregnating wood,
Since a hydrophilic (water-soluble) vinyl monomer is used,
In the manufacturing process, it is not necessary to use an organic solvent, which is currently attracting attention as an environmental problem, as a diluent or a cleaning agent. This makes it possible to treat with water, and since the hydrophilic monomer has biodegradability, wastewater There is also an advantage that the processing can be easily performed.

[0034]

As described above, according to the method for producing a wood-plastic composite of the present invention, after boiling wood, the wood is immersed in a hydrophilic vinyl monomer solution to convert the hydrophilic vinyl monomer as a monomer. Since wood is impregnated, large-scale impregnation equipment is not required, and wood-plastic composites can be manufactured efficiently in a short period of time.In addition, organic solvents must be used as diluents and cleaning agents in the manufacturing process. Therefore, it can be said that the manufacturing method is excellent also in environmental aspects.

Further, by using a hydrophilic vinyl monomer as a monomer, the monomer can sufficiently penetrate into the cell tissue of wood, so that the manufactured wood-plastic composite can be replaced with a conventional one using a hydrophobic monomer. In comparison, the dimensional stability is extremely excellent.

Claims (7)

[Claims] A step of boiling wood in water for a predetermined time; and a step of impregnating the wood with the hydrophilic vinyl monomer by immersing the wood boiled in water in a solution containing a hydrophilic vinyl monomer. Polymerizing the hydrophilic monomer impregnated in the wood. 2. The method for producing a wood plastic composite according to claim 1, wherein a vinyl monomer having a methylol group and a carboxylic acid ester is used as the hydrophilic vinyl monomer. 3. The wood according to claim 1, wherein the wood is impregnated with a plurality of kinds of hydrophilic vinyl monomers, and then the plurality of kinds of hydrophilic vinyl monomers are copolymerized in the wood. A method for producing a plastic composite. 4. After impregnating the wood with a plurality of types of hydrophilic vinyl monomers including a polyfunctional hydrophilic vinyl monomer, the polyfunctional hydrophilic vinyl monomer is used as a crosslinking agent to form a plurality of types of the hydrophilic vinyl monomers. The method for producing a wood-plastic composite according to claim 3, wherein a vinyl monomer is three-dimensionally copolymerized in the wood. 5. The method according to claim 1, wherein the hydrophilic vinyl monomer impregnated in the wood is graft-polymerized with the wood. 6. The wood plastic composite according to claim 2, wherein after the hydrophilic vinyl monomer impregnated in the wood is polymerized in the wood, the lactone cyclization is carried out by further heating at a high temperature. Production method. 7. A wood-plastic composite produced by the method according to claim 1.