JPH0452763B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of the Invention) The present invention relates to a method for manufacturing artificial wooden boards (particle board, fiber board, etc.), and more particularly, to a method for chemically modifying hydroxyl groups in wood components. Relating to a method for producing wooden artificial board materials, which comprises the steps of attaching an adhesive to each of a piece of wood and a piece of untreated wood, stacking the treated wood piece and the untreated wood piece as appropriate, and then press-fitting the pieces together. .

(Prior art and its problems) Traditionally, wooden artificial boards have been developed because of the effective use of resources, the ability to obtain uniform large-sized products, and the ability to obtain boards with various properties depending on the material, adhesive, and pressing force. , construction materials, and a wide range of other uses.

However, on the other hand, it is easy to rot due to erosion by various fungi and damage from insects such as termites, and in today's housing environment where airtightness is high and heating devices are widespread, the occurrence of such rot is difficult. In fact, it has been increasing, and is becoming a major problem as one of the causes of decreased durability of wooden artificial boards.

In order to improve the problem of insect damage, it is common practice to add preservatives and insect repellents during manufacturing, but they are toxic and pose a danger to humans and animals, so the areas where they can be used are limited. There is.

On the other hand, although wooden artificial boards absorb and release moisture depending on the surrounding environmental conditions, so-called breathability, they also swell and swell due to repeated absorption and release of moisture. warp,
It has the essential drawback of causing deformations such as twisting and expansion/contraction.

(Object of the Invention) The object of the present invention has been made in view of the above-mentioned drawbacks, and is a wooden artificial board (particle board,
The purpose of the present invention is to provide a method for manufacturing fiberboard (fiberboard, etc.).

(Structure of the Invention) In order to achieve the above object, the present inventors, as a result of intensive research, have chemically modified the hydroxyl groups in wood components with organic compounds that replace them with non-hydrophilic groups, resulting in a substitution with low reactivity. Focusing on the fact that the treated wood pieces obtained by introducing the group are resistant to decay and have sufficient rot and insect repellent properties without the use of preservatives and insect repellents, they also have a low water absorption rate and are difficult to swell. At least one surface layer of the layers is formed of the treated wood piece.

The gist of the present invention is, in order to achieve the above-mentioned object, to apply adhesive to wood pieces obtained by cutting raw wood material into pieces, and to deposit the adhesive on at least one side of the front and back surfaces of the deposited layer. Wood that is chemically modified with an organic compound that replaces the hydroxyl groups in the wood components with non-hydrophilic groups, and is formed by forming layers of treated wood pieces to which an adhesive is attached, and then press-fitting them together. It is in the manufacturing method of artificial board material.

For convenience, the method for producing a wooden artificial board according to the present invention will be described in detail in a first step of obtaining untreated wood pieces and treated wood pieces, and of the untreated wood pieces and treated wood pieces obtained in this first step, respectively. The explanation will be divided into a second step in which an adhesive is applied to the adhesive, and the adhesive is deposited and laminated as appropriate, and then the adhesive is press-fitted.

In the first step, the untreated wood pieces can be obtained by cutting raw wood into pieces into fibers, chips, flakes, particles, etc. using a chipper or other suitable device. Note that there are no particular restrictions on the species of wood used as the raw material.

In addition, as a method for obtaining treated wood pieces, the untreated wood pieces are chemically treated by contacting them with an organic compound that introduces non-hydrophilic groups by an appropriate means, so that the wood components, particularly the hydroxyl groups of cellulose, are treated. There is a method of chemically modifying.

Here, the organic compound refers to a substance that chemically modifies the hydroxyl group of wood components, particularly cellulose, and introduces non-hydrophilic and low-reactivity substituents into wood pieces. The following esterifying agents and etherifying agents may be mentioned.

Esterifying agents include organic acid anhydrides (for example, acid anhydrides such as acetic acid, propionic acid, and butyric acid), organic acid halides (for example, in addition to the above acids, acid halides such as caproic acid, lauric acid, stearic acid, and methacrylic acid). chlorides, especially acid chlorides), and mixtures of organic acid anhydrides and fatty acids (for example mixtures with trifluoroacetic anhydride or chloroacetic anhydride, propionic acid, caproic acid or lauric acid, etc.). These esterifying agents can be used alone or in combination of two or more.

A catalyst for promoting the reaction with the wood component and/or a solvent for promoting the penetration of the esterifying agent into the wood cell membrane can be added to the esterifying agent. Such catalysts include sulfuric acid, perchloric acid, urea-ammonium sulfate, fatty acid salts, and pyridine, and solvents include benzene, toluene, dimethylformamide, and dinitrogen tetroxide.
Examples include dimethylformamide, and two or more of each may be used as a mixture.

Instead of or in addition to being added to the esterifying agent, these catalysts and/or solvents may be pre-impregnated into the untreated wood piece before being treated with the esterifying agent.

Next, as the etherification agent, for example, 1,2- such as ethylene oxide, propylene oxide, etc.
Activated with epoxides, alkyl halides such as methyl chloride and ethyl chloride, aromatic halides such as benzyl chloride, dialkyl sulfates such as dimethyl sulfate, α-halogen acids such as monochloroacetic acid, and negative groups such as vinyl cyanide. Vinyl compounds, aldehydes such as formaldehyde, etc. can be used.

In the case of an etherification agent, as in the case of an esterification agent, a catalyst (for example, an alkaline catalyst such as sodium hydroxide) and a solvent (for example, a solvent similar to that used in the case of an esterification agent) are added as appropriate. It is also possible to pre-impregnate the untreated wood pieces with the etherifying agent before treatment, although the latter is particularly preferred in the case of catalysts.

Examples of the method of bringing the untreated wood piece into contact with the organic compound include a method of immersing the untreated wood piece in an organic compound solution, or exposing the untreated wood piece to a vaporized organic compound and bringing it into contact. If such a method is carried out under reduced pressure, under increased pressure, or by a reduced pressure method, the impregnation of the organic compound into the untreated wood piece can be further promoted. In addition,
The contact time between the organic compound and the untreated wood chips varies depending on the treatment conditions mentioned above.

Through chemical treatment with such organic compounds, untreated wood chips undergo chemical modifications such as esterification and etherification of the hydroxyl groups of the wood components, especially cellulose, and introduce substituents that are non-hydrophilic and have low reactivity. This results in treated wood pieces.

In addition, in the above-mentioned method, a method of obtaining treated wood pieces by chemically treating raw wood material after cutting it into small pieces was shown, but this is not necessarily the case. , this may be cut into pieces to obtain treated wood pieces.

As a method for applying the adhesive in the second step, for example, there is a method of spraying the adhesive onto each of the falling untreated wood pieces and treated wood pieces.

As a method for depositing, for example, the treated wood pieces to which the adhesive has been adhered are mechanically blown away, relatively small pieces of treated wood are placed on the surface layer using the difference in mass of each treated wood piece, and then the treated wood pieces are placed on the surface layer. A three-layer structure is created by depositing the above-mentioned untreated wood pieces on top of the treated wood pieces to a certain thickness, and then depositing the treated wood pieces on top of the untreated wood pieces in the same manner as described above. Good too.

Furthermore, it is not always necessary to pile up pieces of wood with the same shape, but with wood pieces of different shapes, for example, treated wood pieces in the form of fibers and untreated wood pieces in the form of chips.
It may be deposited as appropriate. For example, after depositing fibrous treated wood pieces to a certain thickness, chip-like untreated wood pieces of increasing particle size are sequentially deposited on top of it,
Furthermore, fibrous treated wood pieces may be deposited thereon to form a three-layer structure.

According to this method, since the front and back surfaces are covered with smooth fibrous treated wood pieces, there is an advantage that an artificial wooden board having excellent water resistance can be manufactured.

In addition, in the above-mentioned method, although the case where a three-layer structure is formed was shown, the case is not necessarily limited to this, and it goes without saying that a two-layer structure or a laminated structure of three or more layers may be formed.

As a method for compression bonding, for example, there is a method in which stacked treated wood pieces and untreated wood pieces are press-fitted in one press operation. It goes without saying that depending on the type of adhesive, heating may be applied during pressurization.

Moreover, the method of press-fitting is not limited to a method of press-fitting in one press-clamping operation, but may be a method of carrying out press-fitting after preliminary press-clamping. For example, after appropriately piling up treated and untreated wood pieces, pre-pressing them to form a plate-like body, stacking these plate-like bodies and pressing them together, produces a multilayer wooden artificial board. There is a way to do it.

This method has the advantage that it is possible to easily produce a wooden artificial board having a treated layer made of treated wood pieces of uniform thickness.

(Explanation of Examples) Examples according to the present invention will be described below.

Example After coarsely crushing wood with a chipper, it was further broken into pieces with a flaker to obtain untreated wood pieces for particle board having an average size of about 12 mm in length, 1.5 mm in width, and 0.5 mm in thickness. Then, a part of this untreated wood piece is placed in a reaction vessel, and after injecting acetic anhydride into this reaction vessel, the reaction vessel is heated to 125°C, and this temperature is maintained for 50 minutes to cause a reaction. A treated wood piece was obtained in which a portion of the hydroxyl groups were replaced with non-hydrophilic acetyl groups. The total dry weight of this treated wood piece is approximately 17% lower than the total dry weight of the original untreated wood piece.
% increase.

Next, the treated wood pieces are mechanically dropped, and a melamine resin adhesive is sprayed to adhere to the treated wood pieces that are falling, and the treated wood pieces to which the adhesive has adhered are deposited uniformly. A pine-like material with a thickness of about 10 mm was obtained. Note that the melamine resin adhesive is applied to treated wood pieces of 100
The solid content was sprayed at a ratio of 4 parts by weight to parts by weight (on a completely dry basis).

Next, untreated wood pieces to which melamine resin adhesive has been applied are deposited uniformly on the top surface of the pine-like object made of treated wood pieces deposited to a uniform thickness in the same manner as described above. A pine-like material with a two-layer structure of about 50 mm was obtained. The above melamine resin adhesive is made from 100 parts by weight of untreated wood pieces (dry equivalent).
The solid content was sprayed at a rate of 7 parts by weight.

Furthermore, treated wood pieces to which melamine resin adhesive has been attached are deposited uniformly on the top surface of the untreated wood pieces, using the same operation as described above, to form a three-layer pine-like structure with a thickness of approximately 60 mm. I got something.
Note that the melamine resin adhesive is applied to treated wood pieces.
The solid content is 4 parts per 100 parts by weight (on a completely dry basis).
It was sprayed in parts by weight.

Finally, the three-layered pine-like material thus obtained is heated and pressurized at 145°C and 30 kg/cm ² to form the front and back layers of treated wood chips, and the core layer is untreated. A 15 mm thick wooden artificial board made of wood chips was obtained.

(Effects of the Invention) As is clear from the above description, according to the present invention, the surface layer on one side exposed to the atmosphere is formed of treated wood pieces, so the wooden artificial board made only of untreated wood pieces It has better preservative and termite-proofing properties than other products, and does not use toxic preservatives and insect repellents.
A wooden artificial board material that is harmless to humans and animals and free from environmental pollution can be obtained.

Furthermore, since the treated wood pieces according to the present invention have a low water absorption rate, the adhesive is not absorbed, so the amount of adhesive applied is reduced, and the softening of the wooden artificial board due to swelling can be prevented, making it an excellent product. A wooden artificial board material having moisture resistance can be obtained.

In addition, since at least one surface layer of the wooden artificial board according to the present invention is formed of treated wood pieces, it is difficult for moisture to reach the untreated wood pieces.
It has excellent dimensional stability. Therefore, it can be used in places where moisture resistance is required, and since it has antiseptic and termite properties, it can be used in a wide range of applications.

Furthermore, since all the layers are not made of treated wood pieces, there is an advantage that it can be manufactured at low cost.

Claims (1)

[Scope of Claims] 1. An adhesive is attached to wood pieces obtained by cutting raw wood material into pieces, and hydroxyl groups in the wood components are added to at least one of the front and back surfaces of the deposited layer formed by depositing this adhesive. A method for producing an artificial wooden board, which comprises forming a layer of treated wood pieces that have been chemically modified with an organic compound substituted with a non-hydrophilic group and attached with an adhesive, and then press-fitting the pieces. 2 The treated wood pieces are wood pieces such as wood fibers and wood chips obtained by cutting wood raw materials into pieces, which are chemically treated with an organic compound that reacts with the hydroxyl groups in the wood components and replaces them with non-hydrophilic groups. The method for manufacturing an artificial wooden board according to claim 1, which is obtained by processing. 3. The treated wood pieces are obtained by chemically treating raw wood with an organic compound that reacts with hydroxyl groups in wood components and substituting them with non-hydrophilic groups, and then cutting the wood into small pieces. A method for manufacturing a wooden artificial board according to claim 1. 4. The method for producing a wooden artificial board according to any one of claims 1 to 3, wherein the organic compound is an esterification agent or an etherification agent.