WO2021006014A1

WO2021006014A1 - Plywood board

Info

Publication number: WO2021006014A1
Application number: PCT/JP2020/024213
Authority: WO
Inventors: 内藤　茂樹; 前田　直彦; 中川　雅博; 大野　宗一郎; 彩乃藤本
Original assignee: パナソニックＩｐマネジメント株式会社
Priority date: 2019-07-11
Filing date: 2020-06-19
Publication date: 2021-01-14
Also published as: JPWO2021006014A1

Abstract

The plywood board comprises a plurality of single boards. The plurality of single boards have been layered and adhered to one another. Each of the plurality of single boards is a single board formed from a plant containing at least one species of saccharide selected from the group consisting of monosaccharides and disaccharides. At least one single board among the plurality of single boards contains a polycarboxylic acid.

Description

Wood laminate

The present disclosure generally relates to a wood laminate including plywood and a single plate laminate, and more particularly to a wood laminate including a plurality of plant single plates containing sugars.

Patent Document 1 discloses a method for joining oil palm thin plates. This method of joining the oil palm thin plate includes a thin plate step, a thin plate drying step, a laminating step, a heating step, a pressing step, and a fixing step.

And, in Patent Document 1, the trunk of the oil palm is used so that the single plate can be joined without adding a component different from the component originally possessed by the oil palm.

However, in Patent Document 1, since only the components originally possessed by oil palm are used, there is room for improvement in the water resistance and strength of the laminated plywood.

On the other hand, Patent Document 2 discloses plywood. The plywood comprises a plurality of single plates bonded together with an adhesive. Then, the adhesive is infiltrated into the fibers exposed on the surfaces of the plurality of single plates.

Specifically, as the adhesive, a melamine resin adhesive, a melamine / urea resin adhesive, a phenol resin adhesive, or the like is used. These adhesives are so-called synthetic adhesives.

As described above, in Patent Document 2, a synthetic adhesive is used, but there is a request to refrain from using such a synthetic adhesive.

Japanese Unexamined Patent Publication No. 2014-019029 Japanese Unexamined Patent Publication No. 2011-08801

An object of the present disclosure is to provide a wood laminated board having excellent water resistance and strength without using a synthetic adhesive.

The wood laminated board according to one aspect of the present disclosure includes a plurality of single boards. The plurality of single plates are laminated and adhered. Each of the plurality of single plates is a single plate of a plant containing at least one sugar selected from the group consisting of monosaccharides and disaccharides. At least one or more of the plurality of single plates contains a polyvalent carboxylic acid.

FIG. 1 is a flowchart of a first manufacturing method of a wood laminated board according to an embodiment of the present disclosure. FIG. 2 is a flowchart of the second manufacturing method of the same wood laminated board. FIG. 3 is a flowchart of a third manufacturing method of the same wood laminated board.

(1) Outline The wood laminated board according to the present embodiment includes a plurality of single boards. A plurality of single plates are laminated and bonded. Each of the plurality of single plates is a single plate of a plant containing at least one sugar selected from the group consisting of monosaccharides and disaccharides. At least one or more of the plurality of single plates contains a polyvalent carboxylic acid. The polyvalent carboxylic acid can penetrate multiple single plates. Adjacent single plates are adhered to each other by reacting at least one saccharide selected from the group consisting of monosaccharides and disaccharides with a polyvalent carboxylic acid.

Therefore, the wood laminated board according to the present embodiment has excellent water resistance and strength without using a synthetic adhesive.

(2) Details <Wood laminated board>
First, the wood laminated board according to this embodiment will be described. The wood laminated board includes a plurality of single boards. The number of single plates included in the wood laminated plate is not particularly limited, but is, for example, in the range of 3 or more and 10 or less. The number of single plates included in the wood laminated plate may be an odd number or an even number. The thickness of the wood laminated board is not particularly limited, but is, for example, in the range of 3 mm or more and 30 mm or less.

A single plate can be obtained by cutting a log of a plant with a cutting machine. Cutting machines include, for example, rotary races and slicers. The thickness of the single plate is not particularly limited, but is, for example, in the range of 2 mm or more and 8 mm or less.

Plant logs are roughly divided into heartwood and sapwood. The heartwood includes the inner layer of the xylem of the tree trunk. The sapwood includes a soft whitish part of wood that occupies the periphery of the wood of the tree. The single plate includes a single plate obtained from the core material and a single plate obtained from the sapwood. The density of the core material is lower than the density of the sapwood. Therefore, if the wood laminated board is manufactured by using a large amount of the single board obtained from the core material, the density of the wood laminated board can be reduced. In addition, by combining an appropriate number of single plates according to the density of the single plate obtained from the core material and the density of the single plate obtained from the sapwood, a wood laminated board with almost the same density can be stably manufactured. can do.

Multiple single plates are laminated and glued together. The fiber direction of each of the plurality of single plates is not particularly limited. The fiber directions of adjacent single plates may be non-parallel or parallel. Non-parallel includes orthogonality. Therefore, the wood laminated board includes plywood, single board laminated material and the like. In plywood, the fiber directions of adjacent single plates intersect. In the single plate laminated material, the fiber directions of adjacent single plates are parallel.

Each of the plurality of single plates is a single plate of a plant containing at least one sugar selected from the group consisting of monosaccharides and disaccharides. The plant is a woody plant and has a woody stem (tree trunk). The plant is preferably palm (palm), and among the palms, oil palm and coconut are preferable. This is because palm contains a relatively large amount of at least one of monosaccharides and disaccharides as compared with other plants.

By the way, the palm oil industry is thriving in Southeast Asia, but palms will not bear fruit in 20 to 30 years, so how to treat such old trees is a problem. This is because the incineration of old trees is prohibited for the purpose of preventing the release of greenhouse gases, and in addition, palms have a high water content, making it difficult to reuse them as wood. For these reasons, it is desired to make effective use of felled old palm trees and the like, and they can be easily obtained as raw materials for wood laminated boards. As described above, in the present embodiment, if the plant is a palm, an old palm tree or the like can be effectively used.

As described above, the plant of the present embodiment contains at least one sugar selected from the group consisting of monosaccharides and disaccharides. These sugars may be contained in the plant at only one type or at least two types.

Monosaccharide is a type of carbohydrate that is not hydrolyzed into simpler molecules. Examples of monosaccharides include fructose, glucose, ribose, arabinose, rhamnose, xylulose and deoxyribose.

Disaccharides produce two molecules of monosaccharides by hydrolysis. That is, the disaccharide is composed of two molecules of monosaccharides glycosidic bonded. Examples of the disaccharide include sucrose, maltose, trehalose, turanose, lactulose, maltulose, palatinose, gentiobiulose, melibiulose, galactosucrose, rutinulose and planteobiose.

The total amount of monosaccharides and disaccharides contained in the single plate is preferably 1% by mass or more of the solid content of the single plate, and more preferably 3% by mass or more of the solid content of the single plate. In this case, a wood laminated board having excellent water resistance and strength can be obtained without using a synthetic adhesive. The method for measuring the total amount of monosaccharides and disaccharides contained in the single plate is not particularly limited. For example, monosaccharides and disaccharides are boiled and extracted from a single plate with hot water, and measured by liquid chromatography-mass spectrometry (LC / MS method) to determine the total amount of monosaccharides and disaccharides contained in the single plate. Can be sought.

The plant may contain polysaccharides. Polysaccharides, in a broad sense, refer to all carbohydrates that produce two or more monosaccharides by hydrolysis, including oligosaccharides such as disaccharides, trisaccharides and tetrasaccharides. However, in the present embodiment, when distinguishing between a disaccharide and a polysaccharide, the polysaccharide does not include the disaccharide. That is, when distinguishing between a disaccharide and a polysaccharide, the polysaccharide is composed of three or more molecules of monosaccharides in a glycosidic bond. Examples of polysaccharides include starch, agarose, alginic acid, glucomannan, inulin, chitin, chitosan, hyaluronic acid, glycogen, cellulose, and oligosaccharides. Examples of oligosaccharides include fructooligosaccharides, galactooligosaccharides, mannan oligosaccharides and stachyose.

At least one or more of the plurality of single plates contains a polyvalent carboxylic acid. The polyvalent carboxylic acid can penetrate multiple single plates. By reacting at least one of a monosaccharide and a disaccharide with a polyvalent carboxylic acid, adjacent single plates are adhered to each other. Further, by reacting at least one of monosaccharides and disaccharides with the polyvalent carboxylic acid, the fibers inside the monosaccharide are also adhered to each other. Compared with polysaccharides, monosaccharides and disaccharides react more easily with polyvalent carboxylic acids and react faster, so that the adhesive strength between single plates and the adhesive strength between fibers can be increased in wood laminated boards. In the present embodiment, the plant may contain a polysaccharide, but in this case, at least a part of the polysaccharide is decomposed by a polyvalent carboxylic acid to become a monosaccharide, and this monosaccharide can contribute to adhesion. Guessed.

The polyvalent carboxylic acid is not particularly limited as long as it is a compound having a plurality of carboxy groups. Examples of polyvalent carboxylic acids include citric acid, tartaric acid, malic acid, gluconic acid, sebacic acid, itaconic acid, succinic acid, oxalic acid, adipic acid, malonic acid, phthalic acid, maleic acid, fumaric acid, and glutaric acid (1). , 5-Pentane diic acid), glutaconic acid and penten diic acid. Acid anhydrides can also be used as the polyvalent carboxylic acid.

Of the polyvalent carboxylic acids listed above, citric acid, tartaric acid, malic acid, gluconic acid, sebacic acid, and itaconic acid are particularly preferable because they can be produced from plants as raw materials. When plants are used as raw materials in this way, the use of fossil resources is suppressed, so that wood laminated boards can be obtained without imposing a burden on the environment. The polycarboxylic acid is synonymous with a polycarboxylic acid.

Preferably, the density (air-dry density) of the wood laminated board is in the range of 0.4 g / cm ³ or more and 0.6 g / cm ³ or less. This makes it possible to further improve the water resistance and strength of the wood laminated board while reducing the weight of the wood laminated board.

Preferably, the peel strength of the wood laminated board is 0.3 MPa or more. Thereby, the strength of the wood laminated board can be further improved. The peeling strength of the wood laminated board is measured in accordance with JIS A 5908.

Preferably, the water absorption thickness expansion coefficient of the wood laminated board is 10% or less. Thereby, the water resistance of the wood laminated board can be further improved. The water absorption thickness expansion coefficient of the wood laminated board is measured in accordance with JIS A 5908.

Preferably, at least one or more of the plurality of single plates contains ammonium sulfate and / or ammonium chloride. Ammonium sulfate and ammonium chloride function as catalysts for the curing reaction of at least one of the monosaccharide and disaccharide saccharides with the polyvalent carboxylic acid. Thereby, the water resistance and strength of the wood laminated board can be further improved. Hereinafter, unless otherwise specified, ammonium sulfate and / or ammonium chloride is referred to as an ammonium salt.

The wooden laminated board according to the present embodiment is not particularly limited, but can be widely used, for example, for furniture, cabinets, building bases (floors, walls, fields), building members, and the like.

<Manufacturing method of wood laminated board>
Next, a method for manufacturing a wood laminated board according to the present embodiment will be described. Examples of the method for manufacturing the wood laminated board include the following first to third manufacturing methods. Hereinafter, they will be described in order.

≪First manufacturing method≫
〔Overview〕
FIG. 1 shows a flowchart of the first manufacturing method. The first manufacturing method includes a temporary drying step S11, a mixing step S12, a secondary drying step S13, and a thermal pressure step S14. In the first manufacturing method, the temporary drying step S11, the mixing step S12, the secondary drying step S13, and the thermal pressure step S14 are indispensable steps. Preferably, the addition step S15 such as squeezing juice is further included. The squeezing and the like addition step S15 is an arbitrary step. In the following, essential steps will be described first, and then arbitrary steps will be described.

[Primary drying step S11]
The primary drying step S11 is a step of drying the single plate. Specifically, a primary dried product can be obtained by drying the single plate within the range of 80 ° C. or higher and 150 ° C. or lower. By drying the single plate in this way, the water content in the single plate can be evaporated and removed. By removing the water, the time required for the subsequent thermal pressure step S14 can be shortened. Therefore, the productivity of the wood laminated board can be improved.

[Mixing step S12]
The mixing step S12 is a step of mixing the primary dried product and the polyvalent carboxylic acid to obtain a mixture. Ammonium salts may be added to the mixture.

The mixture can be obtained as follows. That is, a mixture can be obtained by spraying the polyvalent carboxylic acid aqueous solution toward the primary dried product by spraying or the like. Further, a mixture can be obtained by immersing the primary dried product in a polyvalent carboxylic acid aqueous solution. Further, the polyvalent carboxylic acid aqueous solution can be applied to the primary dried product with a roll or a brush to obtain a mixture. Further, the powder of the polyvalent carboxylic acid can be directly sprayed on the primary dried product to obtain a mixture. The case of adding the ammonium salt is the same as that of the polyvalent carboxylic acid. Ammonium salts may be added to the polyvalent carboxylic acid aqueous solution.

[Secondary drying step S13]
The secondary drying step S13 is a step of drying the mixture. Specifically, a secondary dried product can be obtained by drying the mixture in the range of 80 ° C. or higher and 150 ° C. or lower. By drying the mixture in this way, the water content in the mixture can be evaporated and removed. By removing the water, the time required for the subsequent thermal pressure step S14 can be shortened. Therefore, the productivity of the wood laminated board can be improved.

[Thermal pressure step S14]
The thermal pressure step S14 is a step of heating and pressurizing the secondary dried product for molding. In other words, in the heat-pressing step S14, a plurality of single plates, which are secondary dried products, are stacked and heat-pressed with a hot plate. In the thermal pressure step S14, for example, a press machine having upper and lower hot plates (hot plates) is used.

The molding temperature is not particularly limited, but is, for example, in the range of 140 ° C. or higher and 230 ° C. or lower. The molding pressure is also not particularly limited, but is, for example, in the range of 0.5 MPa or more and 4 MPa or less. The molding time is also not particularly limited, but is, for example, in the range of 10 seconds or more and 15 minutes or less, preferably 1 minute or more and 10 minutes or less.

Here, the curing reaction of the secondary dried product will be described. The curing reaction of the secondary dried product mainly means the reaction of at least one of monosaccharides and disaccharides with a polyvalent carboxylic acid. When the secondary dried product is heat-treated, it is completely cured through a two-step reaction, and adjacent single plates are adhered to each other.

By heat treatment for the curing reaction, sugars (particularly disaccharides) contained in the secondary dried product are hydrolyzed to produce a hydrolysis product. Further, the hydrolysis product is dehydrated and condensed to produce a reaction product of a sugar denaturing product. The condensed water generated at this time is removed by an appropriate method.

For example, when the saccharide is sucrose, it is presumed that the curing reaction proceeds as follows. First, sucrose is hydrolyzed to produce glucose and fructose. Next, the dehydration reaction of fructose produces furfural (specifically, 5- (hydroxymethyl) furfural). Furfural, which is a sugar-modified product, becomes a thermosetting resin, furan resin, by further heat treatment, and is cured in the presence of a polyvalent carboxylic acid. On the other hand, glucose becomes a sugar ester polymer by a dehydration condensation reaction and is cured.

In particular, when the plant used for the single plate is palm (oil palm), it contains 1% by mass or more of monosaccharides and disaccharides in terms of solid content, so that a large amount of thermosetting resin is produced by heat treatment. It is possible to firmly bond the single plates to each other.

The stage of pressurization is not particularly limited. For example, the pressurization may be performed from the start of the heat treatment to the end of the heat treatment, or may be started slightly later than the start of the heat treatment and may be performed until the end of the heat treatment. Further, the heating may be completed a little later than the end of the pressurization.

[Addition step S15 such as squeezing juice]
The squeezing and the like addition step S15 is a step of adding the squeezing and / or the intermediate product to the mixture after the mixing step S12.

The juice is obtained by squeezing the plant. In this case, the plant is preferably a residual material generated when the trunk is cut and the single plate is taken out. Plant pomace (residue) can be discarded. It is highly possible that water-soluble sugars are dissolved in the juice. The water-soluble saccharide is, for example, a saccharide having a large proportion of hydrophilic hydroxy groups with respect to the proportion of hydrophobic hydrocarbon groups. By adding the juice in which such water-soluble sugars are dissolved to the mixture, the water resistance and strength of the wood laminated board can be further improved. The juice may be concentrated into a concentrate and this concentrate may be added to the mixture. It is also possible to use the juice obtained by squeezing a single plate.

On the other hand, the intermediate product is obtained by heat-treating the juice with a polyvalent carboxylic acid. Intermediate products are substances that are in the middle of the curing reaction. By adding the intermediate product to the mixture, the water resistance and strength of the wood laminate can be further improved.

The juice and intermediate products are almost the same as those in the pressing step S22 of the second production method described later.

≪Second manufacturing method≫
〔Overview〕
FIG. 2 shows a flowchart of the second manufacturing method. The second production method includes a mixing step S21, a pressing step S22, and a hot pressing step S23. In the second production method, the mixing step S21, the pressing step S22, and the hot pressing step S23 are indispensable steps. Preferably, the second production method further comprises one or more steps selected from the group consisting of the intermediate product addition step S24, the ammonium salt addition step S25, and the drying step S26. The intermediate product addition step S24, the ammonium salt addition step S25, and the drying step S26 are arbitrary steps.

In the following, the essential steps will be explained first, and then the arbitrary steps will be explained. For convenience of explanation, the optional steps will be described in the order of the ammonium salt addition step S25, the drying step S26, and the intermediate product addition step S24.

[Mixing step S21]
The mixing step S21 is a step of mixing a single plate and a polyvalent carboxylic acid to obtain a mixture.

The mixture can be obtained as follows. That is, a mixture can be obtained by spraying an aqueous solution of a polyvalent carboxylic acid toward a single plate by spraying or the like. Further, a mixture can be obtained by immersing the single plate in a polyvalent carboxylic acid aqueous solution. Further, a mixture can be obtained by applying a polyvalent carboxylic acid aqueous solution to a single plate with a roll or a brush. Further, the powder of polyvalent carboxylic acid can be directly sprayed on a single plate to obtain a mixture.

As described above, when the single plate and the polyvalent carboxylic acid are mixed, the polyvalent carboxylic acid may be in the powder state or in the aqueous solution state. In the case of an aqueous solution, the concentration of the polyvalent carboxylic acid aqueous solution is not particularly limited, but is, for example, in the range of 20% by mass or more and 50% by mass or less.

The content of the polyvalent carboxylic acid is preferably in the range of 3% by mass or more and 15% by mass or less, more preferably 5% by mass or more and 10% by mass or less, based on the total mass of the dried product (described later). Here, the dried product has the same meaning as the dried product obtained after the drying step S26 (described later). As a result, it is possible to suppress a decrease in the strength of the wood laminated board due to the acid and suppress an environmental deterioration due to the elution of the acid.

The content of the polyvalent carboxylic acid is based on the dried product obtained after the drying step S26, but the amount of the polyvalent carboxylic acid to be supplied to the single plate in the mixing step S21 is, for example, as follows. It is possible to ask for it. Experimentally, in the mixing step S21, a known amount of polyvalent carboxylic acid was first supplied to a known amount of a single plate and mixed to obtain a mixture, and then the dried product was subjected to a pressing step S22 and a drying step S26. Obtain (see FIG. 2). Then, the content of the polyvalent carboxylic acid in the dried product or the amount of the polyvalent carboxylic acid contained in the juice obtained in the pressing step S22 is measured. As a result, a guideline can be set as to how much polyvalent carboxylic acid should be supplied in the mixing step S21 to obtain the above-mentioned preferable content. As described above, once the guideline is established, the drying step S26 does not necessarily have to be performed thereafter unless the manufacturing conditions are drastically changed.

[Squeezing step S22]
The pressing step S22 is a step of pressing the mixture to obtain a pressed product and a juice. The pressed product is the pomace (residue) of the mixture. In the pressing step S22, the polyvalent carboxylic acid is pushed into the inside of the single plate. As a result, not only the polyvalent carboxylic acid adheres to the surface layer of the pressed product, but also the polyvalent carboxylic acid can permeate and adhere to the inside of the pressed product. An appropriate squeezing machine such as a pressure press and a pressure roll is used to squeeze the mixture.

Moisture may remain in the pressed product. The water content of the pressed product is not particularly limited, but is, for example, in the range of 20% or more and 200% or less.

On the other hand, there is a high possibility that water-soluble sugars and polyvalent carboxylic acids are dissolved in the juice. Therefore, this squeezed juice can be used for the synthesis of intermediate products (described later).

Since a large amount of water contained in the single plate is accumulated inside the cells, the permeability of the polyvalent carboxylic acid is low. Therefore, in the mixing step S21, when the single plate before pressing and the polyvalent carboxylic acid are mixed, the polyvalent carboxylic acid easily dissolves in the water content of the surface portion of the water contained in the single plate, but the center of the single plate. Polyvalent carboxylic acid is difficult to dissolve in the water content of the portion. In such a state, when the single plate is pressurized in the pressing step S22, the single plate is compressed, and the intracellular water in the central portion of the single plate goes out of the cells and moves to the surface portion to move to the surface portion. The polyvalent carboxylic acid present in the portion is mixed with high-concentration water. After that, when the pressure on the single plate is released, the compressed single plate expands. At this time, the monoplate expands while sucking the water in the surface portion into which the polyvalent carboxylic acid is dissolved into the central portion of the single plate, so that the polyvalent carboxylic acid easily permeates into the inside of the single plate. This is the same regardless of whether the polyvalent carboxylic acid supplied to the single plate is in the powder state or the aqueous solution state.

[Thermal pressure step S23]
The thermal pressure step S23 is a step of heating and pressurizing the pressed product for molding. In other words, in the heat-pressing step S23, a plurality of single plates, which are pressed products, are stacked and heat-pressed with a hot plate. In the thermal pressure step S23, for example, a press machine having upper and lower hot plates (hot plates) is used.

Here, the curing reaction of the pressed product will be described. Since the curing reaction of the pressed product is almost the same as the curing reaction of the secondary dried product in the thermal pressure step S14 of the first production method, the description thereof will be omitted as appropriate. When the pressed product is heat-treated, it is completely cured through a two-step reaction, and adjacent single plates are adhered to each other.

By heat treatment for the curing reaction, sugars (particularly disaccharides) contained in plants are hydrolyzed to produce hydrolysis products. Further, the hydrolysis product is dehydrated and condensed to produce a reaction product of a sugar denaturing product. The condensed water generated at this time is removed by an appropriate method.

In the second production method, since the polyvalent carboxylic acid permeates the inside of the pressed product, not only the surface layer of the pressed product but also the inside, at least one of monosaccharides and disaccharides and the polyvalent carboxylic acid The curing reaction with and can proceed. Therefore, a wood laminated board having excellent water resistance and strength can be obtained. In addition, the wood laminate may also have good dimensional stability.

[Ammonium salt addition step S25]
The ammonium salt addition step S25 is a step of adding the ammonium salt to the mixture. The ammonium salt addition step S25 may be a step simultaneous with the mixing step S21, or may be a step after the mixing step S21. This means that the mixing order of the single plate, the polyvalent carboxylic acid, and the ammonium salt does not matter. However, the ammonium salt addition step S25 is a step prior to the pressing step S22.

It is preferable to add an ammonium salt to the mixture. This will result in the mixture containing single plates, polyvalent carboxylic acids, and ammonium salts. When this mixture is squeezed, the ammonium salts, like the polyvalent carboxylic acid, are more likely to penetrate the inside of the squeezed product. Ammonium salts serve as catalysts for the curing reaction of at least one of the monosaccharide and disaccharide saccharides with the polyvalent carboxylic acid. That is, when the ammonium salt permeates the inside of the pressed product, the curing reaction between at least one of the monosaccharide and disaccharide saccharides and the polyvalent carboxylic acid can proceed not only in the surface layer of the pressed product but also inside. .. Therefore, it is possible to impart more excellent water resistance to the wood laminated board. Since the ammonium salt is a salt having a relatively weak acidity, the strength of the wood laminated board is maintained even if it remains on the wood laminated board.

[Drying step S26]
The drying step S26 is a step of drying the pressed product. Specifically, the dried product can be obtained by drying the pressed product in the range of 80 ° C. or higher and 150 ° C. or lower. By drying the pressed product in this way, the water content in the pressed product can be evaporated and removed. By removing the water, the time required for the subsequent thermal pressure step S23 can be shortened. Therefore, the productivity of the wood laminated board can be improved.

[Intermediate product addition step S24]
The intermediate product addition step S24 is a step of adding the intermediate product obtained by heat-treating the squeezed juice to the pressed product. Here, the intermediate product is a substance in the intermediate stage of the curing reaction in which at least one of monosaccharides and disaccharides is reacted with the polyvalent carboxylic acid. The intermediate product can be synthesized by reacting the juice obtained in the pressing step S22 under conditions looser than the conditions for heat treatment in the hot pressing step S23 (hereinafter, this reaction is referred to as "preliminary reaction"). There is). Examples of the heating conditions for this preliminary reaction include heating at a lower temperature than the conditions for heat treatment in the thermal pressure step S23, and heating for a shorter period of time. The juice is likely to contain a polyvalent carboxylic acid, but if necessary, the polyvalent carboxylic acid may be added and then pre-reacted to synthesize an intermediate product. The intermediate product can become a solid product by evaporating water and the like by heat treatment for a preliminary reaction. This solid material may be added to the pressed product as it is, but preferably, the solid material is crushed into a powder, or the powder is dissolved in a solvent such as water to obtain an aqueous solution. This facilitates the uniform addition of intermediate products to the pressed product.

The amount of the intermediate product added is preferably in the range of 1 part by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the pressed product.

By further containing the intermediate product in the pressed product, excellent water resistance and strength can be imparted to the wood laminated board. The intermediate product may be added to the pressed product before the drying step S26 as described above, or may be added to the dried product after the drying step S26.

≪Third manufacturing method≫
〔Overview〕
FIG. 3 shows a flowchart of the third manufacturing method. The third manufacturing method includes a pressing step S31, a mixing step S32, a drying step S33, and a hot pressing step S34.

[Squeezing step S31]
The pressing step S31 is a step of pressing a single plate to obtain a pressed product and a juice. The pressed product is a single plate with a lower water content than before pressing. For squeezing the single plate, an appropriate squeezing machine such as a pressure press and a pressure roll is used. In the third production method, as in the first production method, the concentrate and / or the intermediate product may be supplied to the mixture. The concentrate is obtained by concentrating the juice. The intermediate product is obtained by processing the juice.

[Mixing step S32]
The mixing step S32 is a step of mixing the pressed product and the polyvalent carboxylic acid to obtain a mixture. Ammonium salts may be added to the mixture.

The mixture can be obtained as follows. That is, a mixture can be obtained by spraying an aqueous solution of a polyvalent carboxylic acid toward a pressed product by spraying or the like. Further, a mixture can be obtained by immersing the pressed product in an aqueous solution of a polyvalent carboxylic acid. Further, a mixture can be obtained by applying a polyvalent carboxylic acid aqueous solution to a pressed product with a roll or a brush. Further, the powder of the polyvalent carboxylic acid can be directly sprayed on the pressed product to obtain a mixture. The case of adding the ammonium salt is the same as that of the polyvalent carboxylic acid. Ammonium salts may be added to the polyvalent carboxylic acid aqueous solution.

[Drying step S33]
The drying step S33 is a step of drying the mixture. Specifically, a dried product can be obtained by drying the mixture in the range of 80 ° C. or higher and 150 ° C. or lower. By drying the mixture in this way, the water content in the mixture can be evaporated and removed. By removing the water, the time required for the subsequent thermal pressure step S34 can be shortened. Therefore, the productivity of the wood laminated board can be improved.

[Thermal pressure step S34]
The thermal pressure step S34 is a step of heating and pressurizing the dried product for molding. In other words, in the thermal pressure step S34, a plurality of single plates, which are dried products, are stacked and heat-press-tightened with a hot plate. In the thermal pressure step S34, for example, a press machine having upper and lower hot plates (hot plates) is used.

Here, the curing reaction of the dried product will be described. Since the curing reaction of the dried product is almost the same as the curing reaction of the secondary dried product in the thermal pressure step S14 of the first production method, the description thereof will be omitted as appropriate. When the dried product is heat-treated, it is completely cured through a two-step reaction, and adjacent single plates are adhered to each other.

<Modification example>
In the first manufacturing method, the temporary drying step S11 may be omitted.

(3) Summary As is clear from the above embodiments and modifications, the present disclosure includes the following aspects.

The wood laminated board according to the first aspect includes a plurality of single boards. The plurality of single plates are laminated and adhered. Each of the plurality of single plates is a single plate of a plant containing at least one sugar selected from the group consisting of monosaccharides and disaccharides. At least one or more of the plurality of single plates contains a polyvalent carboxylic acid.

According to this aspect, a wood laminated board having excellent water resistance and strength can be obtained without using a synthetic adhesive.

In the wood laminated board according to the second aspect, in the first aspect, the density of the wood laminated board is in the range of 0.4 g / cm ³ or more and 0.6 g / cm ³ or less.

According to this aspect, it is possible to further improve the water resistance and strength of the wood laminated board while reducing the weight of the wood laminated board. Furthermore, it is possible to achieve both usability and performance of the wooden laminated board.

In the wood laminated board according to the third aspect, in the first or second aspect, the peel strength of the wood laminated board is 0.3 MPa or more.

According to this aspect, the strength of the wood laminated board can be further improved.

In the wood laminated board according to the fourth aspect, the water absorption thickness expansion coefficient of the wood laminated board is 10% or less in any one of the first to third aspects.

According to this aspect, the water resistance of the wood laminated board can be further improved. Therefore, the wood laminated board is suitable for applications around water and can be used in a place with high humidity.

In the wood laminated board according to the fifth aspect, in any one of the first to fourth aspects, at least one or more of the plurality of single plates contains ammonium sulfate and / or ammonium chloride.

According to this aspect, the water resistance and strength of the wood laminated board can be further improved.

In the wood laminated board according to the sixth aspect, the plant is palm in any one of the first to fifth aspects.

According to this aspect, old palm trees and the like can be effectively used. Further, since palm contains a relatively large amount of at least one of monosaccharides and disaccharides as compared with other plants, the water resistance and strength of the wood laminate are further improved.

The present disclosure will be specifically described by way of examples. However, the present disclosure is not limited to the following examples.

(Example 1)
A palm (oil palm) single plate was used as a single plate of a plant containing at least one sugar selected from the group consisting of monosaccharides and disaccharides. The coconut single plate was obtained by cutting a coconut log with a cutting machine. The thickness of the single palm board is 3 mm.

First, a primary dried product was obtained by drying a single coconut board at 105 ° C.

Next, as a polyvalent carboxylic acid, an aqueous citric acid solution (concentration: 30% by mass) was sprayed at the blending amount shown in Table 1 toward the primary dried product to obtain a mixture.

Next, the mixture was dried at 105 ° C. to obtain a secondary dried product.

Next, five secondary dried products were stacked with the fiber directions orthogonal to each other, regulated by a distance bar so that the distance between the upper and lower hot plates was 9 mm, and then the molding conditions (temperature, temperature, A wood laminated board was manufactured by hot-press molding with pressure and time).

(Example 2)
In Example 1, a wood laminated board was produced in the same manner as in Example 1 except that the coconut single board obtained from the core material was used in a larger amount than the coconut single board obtained from the sapwood.

(Example 3)
A wood laminated board was produced in the same manner as in Example 1 except that a concentrate of squeezed juice was added to the mixture in Example 1. The juice was obtained by squeezing the palm.

(Example 4)
A wood laminated board was produced in the same manner as in Example 1 except that an intermediate product was added to the mixture in Example 1. The intermediate product was synthesized by heat-treating the juice of Example 3 at 105 ° C. and pre-reacting it.

(Comparative Example 1)
A wood laminated board was produced in the same manner as in Example 1 except that a single sugi board was used instead of the single coconut board in Example 1.

(Comparative Example 2)
In Comparative Example 1, a wood laminated board was manufactured in the same manner as in Comparative Example 1 except that the molding conditions (time) were changed.

(Comparative Example 3)
A palm monoplate was used as a plant containing at least one sugar selected from the group consisting of monosaccharides and disaccharides. The coconut single plate was obtained by cutting a coconut log with a cutting machine and then drying it at 105 ° C. The thickness of the single palm board is 3 mm.

First, five palm single plates were stacked with the fiber directions orthogonal to each other and with a urea-melamine adhesive. Next, this is regulated by a distance bar so that the distance between the upper and lower hot plates is 9 mm, and then divided into two stages (specifically, (1) and (2)) under the molding conditions shown in Table 1. ) A wood laminated board was manufactured by hot pressure molding.

(Comparative Example 4)
A wood laminated board was produced in the same manner as in Example 1 except that the polyvalent carboxylic acid was not used in Example 1.

(Comparative Example 5)
In Comparative Example 4, a wood laminated board was manufactured in the same manner as in Comparative Example 4 except that the molding conditions (time) were changed.

<Evaluation>
[Water absorption thickness expansion coefficient]
In order to evaluate the water resistance, a water absorption thickness expansion coefficient test was performed in accordance with JIS A 5908.

[Peeling strength]
In order to evaluate the strength, a peel strength test was conducted in accordance with JIS A 5908.

As is clear from Table 1, in Examples 1 to 4, it can be seen that the wood laminated board has excellent water resistance and strength as compared with Comparative Examples 1 to 5.

In Comparative Example 1, a sugi single plate is used, but since the sugi single plate is not a single plate of a plant containing at least one saccharide selected from the group consisting of monosaccharides and disaccharides, the water absorption thickness expansion It can be seen that both the rate and the peeling strength are poor.

In Comparative Example 2, in Comparative Example 1, the molding time was lengthened to increase the adhesive strength, but as a result, even if the molding time was lengthened, the water absorption thickness expansion coefficient and the peel strength were hardly improved. You can see that.

In Comparative Example 3, a single palm plate is used, but since a urea-melamine adhesive is used without using a polyvalent carboxylic acid, it can be seen that the water absorption thickness expansion coefficient and the peeling strength are not so good. One of the causes is that the urea-melamine adhesive does not penetrate into the inside of the single plate.

In Comparative Example 4, a coconut single plate was used, but since a polyvalent carboxylic acid was not used and no adhesive was used, it can be seen that both the water absorption thickness expansion rate and the peeling strength were poor.

In Comparative Example 5, the molding time was lengthened in Comparative Example 4 to increase the adhesive strength, but as a result, even if the molding time was lengthened, the water absorption thickness expansion coefficient and the peel strength were hardly improved. You can see that.

Claims

It is a wood laminated board provided with a plurality of single boards, and the plurality of single boards are laminated and bonded.
Each of the plurality of single plates is a single plate of a plant containing at least one sugar selected from the group consisting of monosaccharides and disaccharides.
At least one or more of the plurality of single plates contains a polyvalent carboxylic acid.
Wood laminated board.
The density of the wood laminate is in the range of 0.4 g / cm 3 or more and 0.6 g / cm 3 or less.
The wood laminated board according to claim 1.
The peel strength of the wood laminated board is 0.3 MPa or more.
The wood laminated board according to claim 1 or 2.
The water absorption thickness expansion coefficient of the wood laminated board is 10% or less.
The wood laminated board according to any one of claims 1 to 3.
At least one or more of the plurality of single plates contains ammonium sulfate and / or ammonium chloride.
The wood laminated board according to any one of claims 1 to 4.
The plant is a palm,
The wood laminated board according to any one of claims 1 to 5.