WO2009096046A1

WO2009096046A1 - Wood composite material and process for producing the same

Info

Publication number: WO2009096046A1
Application number: PCT/JP2008/056006
Authority: WO
Inventors: Koichi Karukaya; Keisuke Hashimoto; Masafumi Nakatani
Original assignee: Sekisui Chemical Co., Ltd.
Priority date: 2008-02-01
Filing date: 2008-03-28
Publication date: 2009-08-06
Also published as: JP2009179042A

Abstract

A wood composite material which is produced from raw materials containing no harmful substance and which can be sufficiently used as a structural material; and a process for producing the wood composite material. The wood composite material is one produced by piling slender wood chips mixed with a binder while orienting the chips in one direction to form a wood mat and pressing the mat with heating, wherein the binder is a tannin-based adhesive containing tannin derived from acacia or a modified tannin obtained therefrom. The process comprises mixing slender wood chips with a tannin-based adhesive containing (modified) tannin derived from acacia, piling the mixture while orienting the major axes of the wood chips in one direction to form a wood mat, conveying the wood mat to a pressing machine, and heating and pressing it with the pressing machine to bond the wood chips to one another.

Description

WOODY COMPOSITE MATERIAL AND METHOD FOR PRODUCING THE SAME

The present invention relates to a wood-based composite material and a method for producing the same.

After obtaining a slender wooden chip crushed wood as a wood-based molding material, an adhesive is attached to this wooden chip, and the wooden chip is aligned and aligned in the longitudinal direction to form a wooden mat A method for obtaining a wood-based composite material by heating and pressing the wood mat is known. The obtained wood-based composite material has high bending strength by orienting the wood chips (see, for example, Patent Document 1).
Examples of the wood-based composite material obtained by bonding wood chips with an adhesive as described above include a single plate laminate (LVL), particle board, medium density fiber plate (MDF), and hard board.

However, although the above-mentioned conventional wood-based composite materials are recyclable resource materials in which the wood chips used are made of plant resources, they are generally non-renewable natural resources such as phenol resins, melamine resins, and urea resins. Petroleum materials such as isocyanate resins are used as main raw materials. Therefore, the obtained wood-based composite material cannot be said to be a recycling material. Further, there is a problem that harmful volatile substances (for example, formaldehyde) are generated from the product if the manufacturing conditions are not sufficiently controlled.

As a method for solving such a problem, for example, an elongated wooden chip obtained by pulverizing used waste wood with a crusher and classification, and an adhesive mainly composed of tannin, which is a natural component (hereinafter referred to as this). Tannin-based adhesive), and the tannin-based adhesive is heated and cured, and the wood chips made of natural resources that use renewable resources as raw materials by bonding the wood chips with the cured adhesive A method of obtaining a system composite material is known (see, for example, Patent Document 2). The obtained wood-based composite material can have practically sufficient strength, and no harmful volatile substances are generated from the product.
However, in recent years, attention to health awareness and environmental issues has become extremely high, and there is no interest in the presence or absence of harmful substances in raw materials, not to mention the generation of harmful volatile substances from products. It is becoming an important factor that affects the value of a product. As for tannin-based adhesives, instead of the conventional technique using formaldehyde as a curing agent (see, for example, Patent Document 2), a technique for producing a high-strength wood-based composite material that does not contain harmful substances in raw materials is required. It has been.

However, the strength of wood-based composite materials using tannin-based adhesives is not necessarily sufficient for use in areas where excessive stress is applied as a structural material, and the strength decreases when water is absorbed. There was a drawback.
JP 63-107507 A Japanese Patent No. 3515099

An object of the present invention is to provide a wood composite material that does not contain harmful substances in the raw material and can be sufficiently used as a structural material, and a method for manufacturing the same, in view of the problems of conventional wood composite materials. There is.

As a result of intensive studies to solve the above problems, the present inventors have used a tannin-based adhesive containing tannin derived from acacia and its modified tannin as a binder, and one piece of an elongated wooden piece mixed with the binder. The present inventors have found that the above-mentioned problems can be achieved by a wood-based composite material obtained by heating and pressing a wood mat formed by laminating while being oriented in the direction. The present invention has been made based on this finding.

That is, according to the first aspect of the present invention, a wood-based composite material produced by heating and pressing a wood mat formed by laminating elongated wood pieces mixed with a binder while being oriented in one direction. The wood-based composite material is characterized in that the binder is a tannin-based adhesive containing tannin derived from acacia or a modified tannin obtained by modifying it.

Further, according to the second invention of the present invention, there is provided a woody composite material according to the first invention, wherein the binder has adhesiveness.

According to a third aspect of the present invention, there is provided a woody composite material according to the first aspect, wherein the acacia is Morishima acacia.
Such a wood-based composite material can be adapted to the second invention. That is, in the second invention, the same woody composite material as in the third invention can be obtained. In other words, this wood composite material is characterized in that, in the second invention, the acacia is Morishima acacia.

According to a fourth aspect of the present invention, there is provided the wood-based composite material according to the first aspect, wherein the elongated wooden material piece is made of recycled wood.
Such a wood-based composite material can be adapted to the second or third invention. That is, in the second or third invention, the same woody composite material as in the fourth invention can be obtained.

Moreover, according to the 5th invention of this invention, the structural material characterized by using the wood type composite material of the 1st invention is provided.
Such a structural material can be adapted to the woody composite material of any one of the second to fourth inventions. That is, the wood-based composite material can be the same structural material as the fifth invention.

Further, according to the sixth aspect of the present invention, an elongated wooden piece is mixed with an adhesive binder comprising a tannin-based adhesive containing tannin derived from acacia or a modified tannin obtained by modifying it. The wood mat is formed by laminating the long wooden pieces with the longitudinal direction oriented in one direction, and the wood mat is placed on a conveying means and conveyed to a press machine, and heated and pressed by the press machine. Provides a method for producing a wood-based composite material characterized in that wood material pieces are joined together.

Moreover, according to the seventh aspect of the present invention, there is provided the manufacturing method according to the sixth aspect, wherein the acacia is Morishima acacia.

Moreover, according to the 8th invention of this invention, the structural material characterized by using the wood type composite material obtained by the manufacturing method of the 6th invention is provided.
Such a structural material can also be adapted to the wood-based composite material obtained by the manufacturing method of the seventh invention. That is, the wood-based composite material can be the same structural material as that of the eighth invention.

The wood-based composite material of the present invention is composed of a binder composed of a wood material material and a natural product component, and since it is made from natural resources, it can be regenerated and has a harmful catalyst in the tannin-based adhesive. Since it is not used, no harmful substances such as volatile substances are generated, and structural materials such as pillars, beams, foundations, joists, large draws, girders, purlins are used while using the tannin-based adhesive. There is an advantage that it has sufficient strength and water resistance that it can be sufficiently used as rafters, purlins, braces, fire hits and the like.

In addition, according to the method for producing a wood-based composite material of the present invention, when a wood chip mat is conveyed to a press machine, there is a remarkable effect that no noticeable disorder of orientation or stacking failure of the end portion occurs. .

In the present invention, a tannin-based adhesive containing tannin derived from acacia or a modified tannin obtained by modifying the tannin is used as a binder used for bonding wood pieces.
This binder preferably has tackiness, and this tackiness means the property that the wood pieces in contact with each other are difficult to peel off or move due to the sticking of the binder, specifically, In the inclined ball tack test described in JIS Z0237, the ball number at an inclination of 30 degrees is preferably 2 inches or more, more preferably 3 inches or more.

Acacia-derived tannins are generally extracts from acacia trees, have good affinity with wood-based molding materials, have moderate tackiness, and become high strength when cured.
The tree species of acacia is not particularly limited, but Morishima acacia (black wattle) is preferably used.
Tannins extracted from Morishima Acacia are characterized by extremely high reactivity with crosslinking agents and curing agents and low content of impurities such as sugars. Accordingly, when a tannin-based adhesive is used, not only a highly reactive curing agent (for example, formaldehyde) but also a less reactive curing agent (for example, hexamethylenetetramine) is used as a reaction as an adhesive. Since it has high properties, it can be made a high-strength wood-based composite material. In addition, when using a tannin-based adhesive as an aqueous solution, the tannin derived from Morishima acacia has a lower viscosity than other tannins, and thus has an advantage that it is easy to handle and uneven mixing with a wooden piece is difficult. .

Even if impurities such as sugar are mixed in tannin, there is no particular problem. However, when it is intended to obtain a high-strength wood-based composite material, it is better to have less impurities. The purity of tannin can be evaluated by, for example, Stiasny Value (hereinafter referred to as “SV”), and SV is preferably 50 or more, more preferably 70 or more.
The SV can be obtained as follows, for example.
That is, about 100 mg of a pre-dried sample (bark extract or standard catechin) was weighed into a 25-ml round bottom flask, and 10 ml of distilled water, 2 ml of 37% formaldehyde aqueous solution, and 1 ml of hydrochloric acid (10 N) were added in this order. The flask is then heated and boiled for 30 minutes. Immediately after the heating, the sample is filtered at once with a glass filter whose mass has been measured in advance, and washed successively with hot water and methanol. The glass filter is dried in an oven at 105 ° C. overnight, the mass is measured, the residue mass is calculated, and is calculated using the following formula. In order to correct the value, SV of standard catechin is also measured.
SV = (residue mass / sample mass) × (104.1 / SV of standard catechin) × 100

In the present invention, the tannin as extracted may be used as it is, but it may be used as a modified tannin that has been modified and modified if it needs to be modified due to performance or viscosity as an adhesive. Good.
Hereinafter, such tannins and modified tannins may be collectively referred to as (modified) tannins.
The (modified) tannin may be handled as a powder, but in view of ease of handling and the performance of the wood-based composite material obtained using the adhesive, it is preferable to use it in a liquid state by dissolving or dispersing in water. In this case, the (modified) tannin concentration is preferably 20% by mass to 70% by mass. The viscosity is preferably 10,000 cps or less, and is preferably 2,000 cps or less because it is easy to handle when mixing with the wood-based molding material by spraying an adhesive.

Although the tannin-based adhesive used in the present invention contains the above-mentioned (modified) tannin, since tannin alone may not have sufficient adhesive strength, it is preferable to use a crosslinking agent or a curing agent in combination.

The crosslinking agent or curing agent is not particularly limited as long as it has an effect of crosslinking and curing (modified) tannin. Examples of such a crosslinking agent include a tertiary amine, a compound having a methylol group, and an epoxy group. A compound having an isocyanate group, a compound having an aldehyde group, an amino resin, and the like. These may be used singly or in combination of two or more. Among them, a tertiary amine is obtained from a wood-based composite material obtained by using a tannin-based adhesive containing it. It is preferable because it can be excellent.

Examples of the tertiary amine include aliphatic tertiary amines such as triethylamine, triethyltetramine, tributylamine, diethylenetriamine, hexamethylenetetramine, and diethylaminopropylamine, and aromatic tertiary amines such as benzyldimethylamine, dimethylaminomethylphenol, and dimethylaniline. A tertiary amine etc. are mentioned.
These tertiary amines may be used alone or in combination of two or more, but the use of hexamethylenetetramine can increase the strength of the wood composite material described later and increase productivity. It is preferable because no harmful volatile substances are generated and the material cost is low.
Hexamethylenetetramine may be in the form of powder or pellets.

The compound having a methylol group is roughly classified into an aliphatic compound having a methylol group, an alicyclic compound having a methylol group, and an aromatic compound having a methylol group. However, the methylol group has a high reactivity with tannin. The aliphatic compound which has is preferable.
The aliphatic compound having a methylol group is preferably a polyfunctional compound, such as trishydroxymethylaminomethane (2-hydroxymethyl-2-amino-1,3-propanediol), dihydroxymethylaminomethane (2-methyl-2 -Amino-1,3-propanediol), trishydroxymethylnitromethane (2-hydroxymethyl-2-nitro-1,3-propanediol), dihydroxymethylnitromethane (2-methyl-2-nitro-1,3-propanediol), etc. Is mentioned.
These aliphatic compounds having a methylol group may be used alone or in combination of two or more. However, the use of trishydroxymethylnitromethane can make the wood composite material described later high in strength. It is preferable because it is excellent in productivity, does not generate harmful volatile substances, and has a low material cost.
Trishydroxymethylnitromethane may be in the form of powder or pellets.

The compound having an epoxy group is preferably a polyfunctional compound, for example, glycerol polyglycidyl ether, ethylene glycol diglycidyl ether, diethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, resorcinol diglycidyl ether, Examples include 1,6-hexanediol diglycidyl ether, pentaerythritol polyglycidyl ether, diglycerol polyglycidyl ether, polyglycerol polyglycidyl ether, and sorbitol polyglycidyl ether.
These compounds having an epoxy group may be used alone or in combination of two or more.

The compound having an isocyanate group is preferably a polyfunctional compound. For example, tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), polymethylene polyphenylene polyisocyanate (polymeric MDI), xylylene diisocyanate, hexamethylene diisocyanate, tetramethyl. Examples include xylylene diisocyanate, α-dimethylbenzyl isocyanate, norbornane diisocyanate, naphthalene diisocyanate, and diphenylmethane diisocyanate.
These compounds having an isocyanate group may be used singly or in combination of two or more. However, the use of polymeric MDI can increase the strength of the wood composite material described later and increase productivity. It is preferable because no harmful volatile substances are generated and the material cost is low.

Examples of the compound having an aldehyde group include formaldehyde, paraformaldehyde, glyoxal, glutaraldehyde, adipaldehyde, malealdehyde, fumaraldehyde, phthalaldehyde, isophthalaldehyde, terephthalaldehyde, and the like.
These compounds having an aldehyde group may be used alone or in combination of two or more.

Examples of amino resins include urea resins (urea resins), melamine resins, melamine / urea co-condensation resins, and the like.
These amino resins may be used alone or in combination of two or more.

In the tannin-based adhesive, the content ratio of the crosslinking agent or curing agent is preferably 1 to 20 parts by mass, more preferably 3 to 10 parts by mass with respect to 100 parts by mass of (modified) tannin. If this ratio is less than 1 part by mass, curing of (modified) tannin is difficult to proceed, and there is a possibility that a practically sufficient adhesive strength may not be exhibited. There is a risk that it will harden before being added, and it will not be economical.

In the present invention, it is preferable to use a resol-type phenol resin in combination with the crosslinking agent or the curing agent, particularly when attention is paid to applications that require strength and water resistance. By using these in combination, the disadvantages of the single use are complemented, the adhesive has an appropriate cross-linked structure, and the strength and water resistance of the tannin-based adhesive are improved. As a result, the wood-based composite material obtained by bonding wood materials with a tannin-based adhesive can be made to have higher strength, with excellent productivity, no generation of harmful volatile substances, and further material costs However, it can be made an inexpensive wood-based composite material.
A resol type phenol resin may be used independently or may use 2 or more types together.
The content ratio of the resol type phenol resin in the tannin-based adhesive is preferably 1 to 50 parts by mass, more preferably 5 to 25 parts by mass with respect to 100 parts by mass of tannin. If this ratio is too small, curing of tannin is difficult to proceed, and there is a possibility that practically sufficient adhesive strength will not be exhibited, and if it is too large, the ratio of tannin in the adhesive will decrease, and sufficient curing strength will be obtained. It is difficult to obtain, and there is a risk that the curing reaction will be too early and it will harden before being put into the press, and it will not be economical and the adhesive will become too sticky, so the wood-based molding material The admixture adheres to the production line, causing line troubles and increasing the frequency of cleaning.

The tannin-based adhesive is preferably alkaline in pH, more preferably higher than 7 and lower than or equal to 13, more preferably higher than 7 and lower than or equal to 12, particularly using a tertiary amine as a crosslinking agent or curing agent. That is the case.
The aqueous solution of tannin usually has a pH of about 4 to 7, but the tannin aqueous solution can adjust the reactivity and physical properties of the tannin-based adhesive by adjusting the pH.
By making the pH of the tannin-based adhesive alkaline, it is possible to moderately delay the reaction rate of the adhesive, making it easy to handle the adhesive, and providing the adhesive to a wood-based molding material. It will contribute to the improvement of productivity and performance of wood composite materials. This is because, for example, when the pH of the adhesive is acidic, the reaction is too fast and may be cured before being charged into the press, whereas the pH is alkaline, resulting in an appropriate reaction rate. Therefore, the adhesive is not cured until it is put into the press machine after blending the adhesive, and it is clearly shown that the adhesive is cured only when heated and pressed by the press machine.
In addition, when the pH of the adhesive is acidic, excessive decomposition of the tertiary amine may occur when the adhesive is heated and cured, and harmful volatile substances may be generated. Thus, excessive decomposition of the tertiary amine is suppressed when the adhesive is heat-cured, thereby preventing generation of harmful volatile substances.

In addition, by making the pH alkaline, the reactivity of the resol-type phenol resin is improved, and the crosslinking reaction with tannin proceeds efficiently. As a result, the strength and water resistance of the tannin-based adhesive are improved, and at the time of pressing. The hydrolysis of hemicellulose in the wood-based molding material and the softening of the wood-based molding material thereby are further promoted. Due to this softening action, it is possible to consolidate the wood chips even at low pressing pressure, the density in the thickness direction of the product can be made uniform, the water resistance is improved, and the pressure during pressing can be lowered. preferable. As a result, product performance such as strength and water resistance is improved.

However, if the pH is higher than 13 and the alkalinity becomes too strong, it is necessary to be careful in handling, and the wood component (for example, hemicellulose) is partially decomposed and denatured through the softening, so that the wood composite material becomes Since there is a possibility of coloring black, it is not preferable.
When tannin is provided as an aqueous solution, the pH is preferably adjusted in advance before mixing with the crosslinking agent or curing agent. The alkali for adjusting the pH is not particularly limited, but sodium hydroxide and potassium hydroxide are preferable.

Moreover, the tannin-based adhesive may contain various additives usually used for this type of adhesive as long as the intended purpose is not impaired. Examples of the additive include water-soluble polymers such as polyvinyl alcohol, vinyl acetate emulsion, styrene butadiene rubber (SBR), and acrylic emulsion; organic solvents such as toluene, xylene, methanol, ethylene glycol, and polyethylene glycol; phthalate esters Plasticizers such as film forming agents; extender pigments such as clay, calcium carbonate, calcium sulfate, talc, mica, silicate powder; fillers or extenders such as wheat flour, corn starch, wood flour, coconut shell powder; titanium oxide, etc. Color pigments; dyes; thickeners; viscosity modifiers; dispersants; emulsifiers; wetting agents such as urea; antifoaming agents; anti-freezing agents; antiseptics; And a reagent for quality. Furthermore, in order to improve strength reinforcement, viscosity, mechanical properties, etc., urethane resin, polyester resin, alkyd resin and the like, prepolymers thereof, starch, chitosan, lignin, resorcinol and the like may be contained.

The wood-based composite material of the present invention is obtained by mixing an elongated wood material piece with an adhesive binder comprising a tannin-based adhesive containing a tannin derived from acacia or a modified tannin obtained by modifying it. A piece of wood is laminated with its longitudinal direction oriented in one direction to form a wood mat, and this wood mat is placed on a transporter and placed in a press machine. It can be manufactured by bonding pieces of material.

It is preferable to use Morishima Acacia as the acacia.

In addition, as the raw material tree species of the above-mentioned wood material pieces, conifers such as cedar, cypress, pine, spruce, and fur, broad-leaved trees such as birch, apiton, sengonlaut, and aspen can be cited. Plant material is also included.

Examples of forms that can be used include raw materials such as the above-mentioned logs, thinned wood, scraps generated at factories and residential construction sites, waste pallet materials discarded after transportation of components, and demolition waste materials generated at the time of building demolition. It is done. In particular, scrap materials such as demolition waste, waste pallet material, thinned wood, scraps generated during lumbering, and wood materials used as fuel and papermaking raw materials are preferred.

In the method of processing the above raw materials into elongated wooden pieces, a hammer mill, a uniaxial crusher that crushes wood by rotating a roll with a blade on its surface, a biaxial or multiaxial crusher with a structure in which rotating blades are engaged However, it is also possible to use a rotary cutter that cuts a veneered product into a chopsticks shape to make a stick, a flaker that cuts a log or the like with a rotary blade to make a strand, and the like. In particular, when a recycled material is used as a raw material, a crusher is preferable in that foreign substances are easily mixed and the durability of the blade is high.

Since the elongated wooden piece obtained by the above method has a variation in size, a wooden piece of a predetermined size is obtained by a classification process. As a classification method at this time, there are a roller screen method, a vibrating mesh method, a wind selection method, and the like. The elongated wooden piece is preferably 20 to 150 mm long and 1 to 15 mm thick.

It is preferable to adjust the moisture content of the classified and slender wooden pieces in a certain range. By keeping the moisture content constant, there is no variation in the quality of the molded product during production. A preferable water content is 0 to 14%.

細長い The long and slender wood pieces that have been classified and adjusted in water content are mixed with the binder. The amount of the binder to be mixed depends on the density, shape and surface state of the wood piece, but is usually preferably 1 to 20% by weight with respect to the weight of the wood piece.

Examples of the means for mixing the wood piece and the binder include a method in which the wood piece and the binder are put into a mixer such as a Henschel mixer and mixed. However, when the binder is liquid, it is on a conveyor or in a drum blender. When a binder is attached to the surface of the wood material piece by using an application means such as spray on the wood material piece, etc., a structural material having a uniform and stable strength can be obtained.

The mixture of the above-mentioned wood material pieces and the binder is laminated while being oriented in a certain direction to form a wood-based mat. Specifically, it can be performed by putting a piece of wood material into a mold and laminating it. The orientation in a certain direction means that the fiber direction of the wood chip is oriented at an angle of less than 20 degrees on the average with respect to the longitudinal direction of the formed wood-based composite material. In order to orient in one direction, an orientation laminating apparatus such as a forming type divided at regular intervals or a disk orienter used in the manufacture of an oriented strand board (OSB) or the like is used.

After forming the mat, it is put into a heatable press machine and press-molded. Heating and pressurization may be performed simultaneously, may be performed after pressurization, or may be performed after heating. Examples of the pressing device include a method of transferring heat from the surface of a wooden piece like a hot plate to the inside by heat transfer, and a method of directly heating the inside such as steam injection and high frequency heating.

The wood-based composite material obtained in this way can have various shapes and can be used for various applications. In particular, it is suitable for structural materials such as pillars, beams, foundations, joists, large draws, girders, purlins, rafters, purlins, braces, and fire strikes.

Hereinafter, the present invention will be described in more detail with reference to comparative examples, but the present invention is not limited to these examples.

Example 1
The wood-based composite material was molded by the following manufacturing process.
The long wooden piece is 1-8mm thick using a wave roller screen device (manufactured by Taihei Co., Ltd.), which is a roller screen type, using a chip for board (crushed by a single screw crusher) purchased from a wood waste disposal contractor. Classified wooden chips.
After adjusting the wood chip to a moisture content of 6%, 10% by weight of tannin-based adhesive as a binder was added to the drum blender and mixed. The tannin adhesive used was prepared by the following procedure. First, Morishima acacia tannin powder was dissolved in hot water at about 40 ° C. to a concentration of 40% by mass. Thereafter, the pH was adjusted to 10 with an aqueous sodium hydroxide solution having a concentration of 50% by mass. A 40% by mass aqueous solution of hexamethylenetetramine was used as a curing agent, and mixed so that hexamethylenetetramine was 10 parts by mass with respect to 100 parts by mass of tannin. The tackiness of the tannin adhesive was measured according to JIS Z 0237. The ball number was 5 inches.

Next, the blended binder and the wood chip were put into an OSL forming machine (manufactured by Taihei Co., Ltd.) and put into a forming mold (vertical 2000 mm, horizontal 500 mm, height 100 mm).
In the forming mold, a metal partition plate (thickness: 2 mm) was used, which was divided into 10 equal parts at 50 mm intervals, and oriented and laminated in one direction.
Next, the forming mold and the partition plate were removed, and the mat was put into a press machine. When the wood chip mat was transported to the press machine, it was transported by placing it on a carriage at a distance of about 10 m. However, due to its adhesiveness, there was no noticeable disruption of orientation or collapse of the stack of the edges.
The mold of the press machine is 2500 mm long, 500 mm wide, and 150 mm high. The press machine was a heat transfer type, and a 300 t press made by Kawasaki Oil Works was used. The plate-shaped molded body having a final shape of 2000 mm × 500 mm × 30 mm was obtained by pressing for 20 minutes at a heating temperature of 180 ° C. and a pressure of 3 MPa.
The three-point bending strength of the formed body was measured and found to be 43 MPa. The water absorption thickness expansion coefficient was measured and found to be 10%.

(Comparative Example 1)
Example 1 is the same as Example 1 except that quebracho tannin was used as the tannin-based adhesive.
The tackiness of the tannin adhesive was measured according to JIS Z 0237. The ball number was 5 inches.
When the wood chip mat was transported to the press machine, it was transported by placing it on a carriage at a distance of about 10 m. However, due to its adhesiveness, there was no noticeable disruption of orientation or collapse of the stack of the edges.
When the three-point bending bending strength of the formed body was measured, it was 34 MPa. The water absorption thickness expansion coefficient was measured and found to be 12%.

(Comparative Example 2)
The same as Example 1 except that an isocyanate adhesive was used as the binder.
The tackiness of the isocyanate adhesive was measured according to JIS Z0237. The ball number was 2 inches.
When transporting a wood chip mat to a press machine, if it is transported on a carriage for a distance of about 10 m, the orientation is disturbed over the entire mat because it does not have stickiness, and significant stacking failure occurs at the edges. Occurred.
When the three-point bending bending strength of the formed body was measured, it was 33 MPa. The water absorption thickness expansion coefficient was measured and found to be 8%.

According to the wood-based composite material of the present invention, it is composed of a binder composed of a wood material piece and a natural product component, and uses natural resources as a raw material, so that it can be regenerated and is a harmful catalyst for tannin-based adhesives. No toxic substances such as volatile substances are generated, and structural materials such as pillars, beams, foundations, joists, large draws, girders are used while using the tannin-based adhesive. There is an advantage that it can have sufficient strength and water resistance that can be used sufficiently as a purlin, rafters, purlins, braces, fire hits, etc., and according to the method for producing a wood-based composite material of the present invention When a wood chip mat is conveyed to a press machine, there is no noticeable disorder of orientation or stacking failure at the end, which is very useful in the industry.

Claims

A wood-based composite material produced by heating and pressing a wood mat formed by laminating elongated wood pieces mixed with a binder in one direction, wherein the binder is tannin derived from acacia or A wood-based composite material characterized by being a tannin-based adhesive containing a modified tannin obtained by modifying it.
2. The woody composite material according to claim 1, wherein the binder has adhesiveness.
The woody composite material according to claim 1, wherein the acacia is Morishima acacia.
2. The wood-based composite material according to claim 1, wherein the elongated wooden material pieces are made of recycled wood.
A structural material comprising the woody composite material according to any one of claims 1 to 4.
A long wooden piece is mixed with an adhesive binder made of a tannin-based adhesive containing a tannin derived from acacia or a modified tannin obtained by modifying it, and the long wooden piece is unidirectional in its longitudinal direction. The wood mat is formed by being oriented and laminated, and the wood mat is placed on a transport means and transported to a press machine, and the wood material pieces are bonded to each other by being heated and pressed by the press machine. A method for producing wood-based composite materials.
The manufacturing method according to claim 6, wherein the acacia is Morishima acacia.
A structural material using a wood-based composite material obtained by the production method according to claim 6 or 7.