JP2008238448A - Wood composite material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wood composite material capable of suppressing such deformation as expansion caused by stress after molding. <P>SOLUTION: In the wood composite material in which wood pieces are compressed together in the presence of steam and are integrated by sticking, the wood composite material is made by impregnating the wood pieces in an acidic water solution in advance. This is obtained by a method comprising a wood piece group forming process to collect the wood pieces the surface of which keeps an adhesive sticking to obtain a wood piece group, and the sticking process to compress the wood piece group in the presence of steam to stick and integrate the wood pieces together, and impregnating the wood pieces with the acidic water solution in advance, or a method comprising the wood piece group forming process to collect the wood pieces the surface of which keeps the adhesive sticking to obtain the wood piece group, and the sticking process to compress the wood piece group in the presence of steam to stick and integrate the wood pieces together, and impregnating the wood pieces with the acidic water solution in advance. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a wood-based composite material, and more particularly to a wood-based composite material capable of suppressing deformation such as expansion due to stress after molding.

Wood materials such as plywood, particle board, laminated wood, single-plate laminated material, and OSB (Oriented Strand Board) are widely used for residential building materials.
Molded products that are produced by highly compressing like particle board retain compressive stress in the compression direction of the molded product, that is, the surface direction of the particle board, and expand in this direction due to wet heat. There was a problem. To solve this problem, means such as addition of a water repellent and resin impregnation have been developed, but there are problems of cost and long-term dimensional stability. In addition, although a technique for solving the expansion problem by compressing while heating with water vapor has been developed, there is a problem that the process takes a long time.
In addition, functional wood materials in which various functional agents are impregnated into a wood element have been proposed (see, for example, Patent Document 1), but cannot cope with deformation such as expansion due to stress after molding. Absent.

JP 2006-297890 A

  Under such circumstances, an object of the present invention is to provide a wood-based composite material capable of suppressing deformation such as expansion due to stress after molding.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have previously impregnated an acidic aqueous solution as a wood piece in a wood composite material in which wood pieces are compressed and bonded together in the presence of water vapor. By using it, it discovered that the said subject was achieved and came to make this invention based on this knowledge.

  That is, according to the first invention of the present invention, in the wood-based composite material in which the wood pieces are compressed and bonded together in the presence of water vapor, the wood pieces are impregnated with an acidic aqueous solution in advance. A composite material is provided.

  According to a second aspect of the present invention, there is provided a wood-based composite material according to the first aspect, wherein the acid used in the acidic aqueous solution is solid at room temperature.

  Further, according to the third invention of the present invention, the wooden piece group forming step of collecting the wooden pieces having the adhesive attached to the surface to obtain the wooden piece group, and compressing the wooden piece group in the presence of water vapor A method for producing a wood-based composite material according to the first or second invention, wherein the wood-based composite material is pre-impregnated with an acidic aqueous solution. A manufacturing method is provided.

  According to the fourth aspect of the present invention, a laminated mat forming step of forming a laminated mat by laminating a group of wooden pieces with an adhesive attached to the surface of each wooden piece, and the laminated mat in the presence of water vapor. A method for producing a wood-based composite material according to the first or second invention, comprising a step of compressing and adhering wood pieces together, wherein the wood pieces are impregnated with an acidic aqueous solution in advance. A method for producing a composite material is provided.

  According to the woody composite material of the present invention, remarkable effects such as suppression of deformation such as expansion due to stress after molding can be obtained.

The woody composite material of the present invention is characterized in that wood pieces are compressed and bonded together in the presence of water vapor, and the wood pieces are impregnated with an acidic aqueous solution in advance.
Hereinafter, the wood piece, the acidic aqueous solution, the adhesion integration, the production method, and the like will be described in detail for the wood-based composite material.

<Wood pieces>
The wood pieces used in the present invention are not particularly limited, for example, thinned wood, scraps generated in factories and residential building sites, waste pallet materials discarded after transportation of members, demolition waste materials generated at the time of building demolition, wood chips, A veneer etc. are mentioned.
The size of the wood piece is not particularly limited, but a fine one is suitable because the impregnation rate of the acidic aqueous solution is fast and re-drying is easy. Moreover, it is preferable to select the size of the wooden piece depending on the use of the molded product. If strength is required, a piece of wood with a longer fiber length is suitable.
Individual pieces of wood are usually assembled and used in the form of pieces of wood. As this wood piece group, what contains 70 mass% or more of wood pieces having a length of 20 mm to 150 mm is preferable. When the content ratio of the wood pieces in such a wood piece group is less than 70% by mass, the strength of the obtained molded product may be insufficient or the appearance may be deteriorated.
The method for preparing such a group of wood fragments is not particularly limited. For example, the wood fragments of irregular sizes obtained by crushing or the like are classified using an appropriate classifier such as a wave roller classifier. The method of doing is mentioned. The wave roller classifier is a device that continuously classifies based on the thickness of the wood pieces.

<Acid aqueous solution>
The acid used in the acidic aqueous solution is not particularly limited, and various organic acids and inorganic acids are used. Preferably, the organic acid is, for example, citric acid, malic acid, itaconic acid, succinic acid, fumaric acid, tartaric acid, Lactic acid, adipic acid, gluconic acid, acetic acid, propionic acid, etc. include inorganic acids such as phosphoric acid and boric acid. Among them, it is solid at room temperature, and is highly safe for the human body and the environment. Preferred organic acids are citric acid, malic acid, itaconic acid, succinic acid, fumaric acid, tartaric acid, lactic acid, adipic acid, gluconic acid and the like.
Here, normal temperature refers to the higher of the environment in which the wood-based composite material is manufactured or the environment in which it is used, and normally 20 ° C. is the target.
Use of a liquid acid at room temperature not only has a problem in the working environment, but there is a risk that the acid is easily detached from the wood-based composite material after molding and adversely affects the human body and surroundings. Further, in the case of a volatile acid, an odor is generated, which may be undesirable.

The wooden piece is impregnated with an acidic aqueous solution by immersing the wooden piece in the acidic aqueous solution, applying the acidic aqueous solution to the wooden piece by spraying or spraying it, and spraying the wooden piece under reduced pressure and pressure conditions. There are a pressure reduction treatment and a pressure treatment in which a piece is impregnated with an acidic aqueous solution. When the wood piece is small, the acidic aqueous solution is sufficiently impregnated even under normal pressure treatment, and therefore it is not necessary to use a reduced pressure treatment or a pressurized treatment.
In the impregnation step, the temperature of the wood pieces and the acidic aqueous solution can also be adjusted. For example, if the acidic aqueous solution is heated, the liquid permeability is improved, and the impregnation property of the acidic aqueous solution can be improved.
Moreover, according to the so-called hot / cold bath method of treating with a heated acidic aqueous solution and then with an unheated acidic aqueous solution or a cooled acidic aqueous solution, the permeability can be further increased, Warming the wood pieces is also an effective means for improving the permeability.
When immersing the wood pieces in the acidic aqueous solution, if the concentration of the acidic aqueous solution is too low, the immersion of the acid into the wood pieces becomes insufficient, and if it is too high, it is impregnated more than necessary and is not economical. % Is preferred.

The acidic aqueous solution treatment may be performed at room temperature, but may be performed by heating to promote the impregnation of the acidic aqueous solution into the wood pieces. If the heating temperature in this case is too high, the working environment becomes worse, the apparatus becomes large, and a lot of energy is required.
If the time for immersing the wood pieces in the acidic aqueous solution is too short, the immersion of the acidic aqueous solution in the wood pieces becomes insufficient, and if it is too long, it is not efficient, so 1 to 10 minutes is preferable.
<Adhesion integration>

After the impregnation treatment, a molded product can be obtained by bonding and integrating the wood pieces. Usually, the wood piece subjected to the impregnation treatment is preferably dried in advance to a moisture content suitable for adhesion and molding.
An adhesive is generally used to bond and integrate the wood pieces. Examples of adhesives include urea resin adhesives, melamine / urea co-condensation resin adhesives, phenol / melamine co-condensation resin adhesives, phenol resin adhesives, resorcinol resin adhesives, isocyanate adhesives, and water-based polymer-isocyanates System adhesives and the like. Although adhesion integration without an adhesive is possible, it is generally inferior in strength at the time of water absorption compared to the case where an adhesive is used.

For the adhesive integration, heat treatment in the presence of water vapor, preferably heat compression treatment in the presence of water vapor, heat is transferred quickly to the center even in thick materials, and the wooden pieces are softened by the water vapor, and further the pressure during compression This is desirable because the effect of reducing the compression stress of the wood piece can be reduced. If the heat is not transmitted to the center, a so-called puncture that causes a bonding failure and cracks in the central portion of the material is likely to occur, and a problem that the strength properties are deteriorated even if the puncture does not occur.
In the heat compression treatment, the pressure during compression is usually in the range of 0.5 to 20 MPa, preferably 1 to 10 MPa. If this pressure is too low, the mechanical strength of the resulting molded product will decrease, and if it is too high, the wood pieces will break or uneven specific gravity tends to occur.
In addition to these heating methods, other heating methods may be used in combination.
It is important that such heat treatment or heat compression treatment is performed so that the impregnated acid does not deteriorate and the predetermined function is not sufficiently exhibited. As deterioration under such heating conditions, deactivation due to an acid oxidation reaction, deactivation due to reaction with an adhesive, decomposition, and the like are presumed.

The water vapor is preferably in the temperature range of 150 to 200 ° C. If the temperature of the water vapor is less than 150 ° C., heat transfer is insufficient and the heating time for bonding and integrating the wood pieces becomes long, which is not economical, and the softening of the wood pieces becomes insufficient. Exceeding this will cause the equipment to become large and the wood material to be easily degraded.
For the heat treatment and heat compression treatment, it is preferable to use a water vapor jet apparatus or a high frequency heating apparatus.
Heating with water vapor causes hydrolysis of the components inside the wood, and this hydrolysis has the effect of relaxing the deformation stress of the wood. In the present invention, since the wood piece is further impregnated with the acid, the above hydrolysis is promoted, and as a result, the effect of relieving the deformation stress of the wood is promoted, so that expansion due to water absorption after molding is also suppressed. The

<Wood based composite material>
In the woody composite material of the present invention, the molding method, the apparatus used therefor, the molding conditions, etc. are not particularly limited, but generally the wood pieces are laminated before the wood pieces are bonded and integrated. In the laminating step, in particular, when the wood pieces are laminated with the fiber direction aligned in one direction, the molded article has anisotropy in the direction in which various physical properties are aligned. When used as a column, beam, shaft material, etc., it is preferable to perform such lamination. In the laminating process, when the fiber directions of the wood pieces are randomly laminated, or the layers in which the fiber directions of the wood pieces are aligned in one direction are multiple layers, the adjacent layers are perpendicular to each other in the direction in which the fiber directions are aligned. When laminated in this manner, the performance as a face material is excellent.

A typical example of a method for producing a wood-based composite material is as follows.
(I) A wood piece group forming step for gathering wood pieces having an adhesive attached to the surface to obtain a wood piece group, and a bonding step for compressing the wood piece group in the presence of water vapor to bond the wood pieces together A method of impregnating a wooden piece with an acidic aqueous solution in advance.

  (Ii) A laminated mat forming step of forming a laminated mat by laminating a group of wooden pieces with an adhesive attached to the surface of each wooden piece, and compressing the laminated mat in the presence of water vapor to bond the wooden pieces together A method for producing a wood-based composite material according to the first or second invention, wherein the wood piece is impregnated with an acidic aqueous solution in advance.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited at all by these examples.

Example 1
Wood fragments of residential building materials and waste wood fragments were classified with a wave roller type classifier to prepare wood pieces having a thickness of 1 to 11 mm, a length of 20 to 150 mm, and a length / thickness ≧ 10. This wood piece was immersed in a 1% strength aqueous citric acid solution at 0 ° C. for 3 minutes. Thereafter, it was dried in an oven to a moisture content of 3%. This wood piece was put into a drum blender, and 40 g of an adhesive (Sumitomo Bayer Urethane Co., Ltd., Sumidur 44V10) was applied per 1 kg of the wood piece. Thereafter, the laminated mat is oriented and laminated so that the length direction of the wood piece substantially coincides with the length direction of the molded body to be obtained, and this laminated mat is used as a heating press device using a steam jet press device. A compact was formed by pressing for 5 minutes at a surface pressure of 2.5 MPa while heating to ℃. This molded body was adjusted to a moisture content of 10% to obtain a wood-based composite material product having an air-dry density of 0.75 g / cm ³ .

Example 2
A product was obtained in the same manner as in Example 1 except that the concentration of the citric acid aqueous solution was changed to 0.1%.

Comparative Example 1
A comparative product was obtained in the same manner as in Example 1 except that the wood piece was not subjected to the acidic aqueous solution impregnation treatment.

Comparative Example 2
A comparative product was obtained in the same manner as in Example 1 except that a hot plate press was used as the heating press device.
The hot plate temperature was 180 ° C. and the surface pressure was 5 MPa.

Each product obtained was used as a sample to evaluate the following items.
1) Appearance: The sample was visually checked for cracking and chipping problems.
2) Water absorption thickness expansion coefficient: In accordance with JIS A 5908 Particle Board, for each product, 6 test pieces having a length direction of 50 mm, a width of 50 mm, and a thickness (compression direction) of 38 mm were cut out. The average value of the results of measuring the expansion coefficient in the compression direction by immersing in room temperature water for an hour was obtained.
The evaluation results are shown in Table 1.

  As shown in Table 1 above, the products of Examples 1 and 2 and Comparative Example 1 had no problem in appearance, but in the case of the test piece of Comparative Example 1, the water absorption thickness expansion coefficient was the test of each example. It was bigger than one piece. Further, in the case of the comparative product of Comparative Example 2, a crack occurred in the vicinity of the center, which was a so-called puncture state.

  The wood composite material of the present invention can be used as a housing building material such as a pillar, a beam, a face material, etc., which can not be used as a conventional housing building material. Become.

Claims (4)

  A wood-based composite material in which wood pieces are compressed and bonded and integrated in the presence of water vapor, and the wood pieces are impregnated with an acidic aqueous solution in advance.   The woody composite material according to claim 1, wherein the acid used in the acidic aqueous solution is solid at room temperature.   It includes a wood piece group forming step for gathering wood pieces having an adhesive attached to the surface to obtain a wood piece group, and a bonding step for compressing the wood piece group in the presence of water vapor to bond and integrate the wood pieces together 3. The method for producing a wood-based composite material according to claim 1, wherein the wood piece is impregnated with an acidic aqueous solution in advance.   Laminate mat formation process to form a laminated mat by laminating a group of wood pieces with adhesive attached to the surface of each wooden piece, and an adhesion process to compress and laminate the laminated matte in the presence of water vapor A method for producing a wood-based composite material according to claim 1 or 2, wherein a wooden piece is impregnated with an acidic aqueous solution in advance.