JP7407403B2 - Manufacturing method for wood laminates - Google Patents

Description

The present disclosure generally relates to a method for manufacturing a wood laminate, and more particularly to a method for manufacturing a wood laminate using a plant containing sugars.

Patent Document 1 discloses a composite consolidated plywood. Composite consolidated plywood is consolidated by laminating an inner laminated material and an outer surface material. The internal laminate is a stack of multiple veneers made of oil palm wood. The outer surface material is another veneer made from a tree species other than oil palm wood. The outer surface material is laminated on at least one of the outer surfaces of the outermost layer of the internal laminate material. Patent Document 1 discloses that this allows a composite consolidated plywood with excellent surface quality to be obtained.

On the other hand, Patent Document 2 discloses a laminate. A laminate is formed by laminating and adhering a surface plate to the surface of a composite plate. Composite boards are made by pasting together veneers made of natural wood. The top plate consists of wood fiberboard or wood chipboard obtained from softwood wood. Accordingly, Patent Document 2 discloses that the laminate is suitably used as a surface material or decorative material for interior decoration of buildings, furniture, etc.

Conifers or hardwoods are used as decorative veneers in the composite consolidated plywood described in Patent Document 1 and the laminate described in Patent Document 2, but in recent years, conifers and hardwoods have been decreasing on a global scale. There is a tendency. Therefore, currently, consideration is being given to manufacturing wood laminates without using softwood or hardwood.

However, for example, in Patent Document 1, if the outer surface material is formed from a tree species other than softwood or hardwood, the surface quality of the composite consolidated plywood may deteriorate, and furthermore, there is room for improvement in water resistance. obtain.

Japanese Patent Application Publication No. 2018-122461 Utility Model Publication No. 5-076702

An object of the present disclosure is to provide a method for manufacturing a wood laminate that can produce a wood laminate with excellent water resistance without using a softwood or hardwood veneer for the surface layer.

A method for manufacturing a wood laminate according to one aspect of the present disclosure includes a veneer manufacturing process, a catalyst supply process, and an adhesion process. In the veneer manufacturing process, a saccharide-containing veneer is manufactured from a plant containing saccharides. In the catalyst supply step, a polyhydric carboxylic acid is supplied to the saccharide-containing veneer to obtain a catalyst-containing veneer. In the bonding step, the catalyst-containing veneer is stacked on both sides or one side of the core material, and a heat-pressure treatment is performed to bond the catalyst-containing veneer and the core material. The sugar-containing veneer is more easily compressed than the core material.

1A and 1B are schematic cross-sectional views showing a method for manufacturing a wood laminate according to a first embodiment. 2A to 2C are schematic cross-sectional views showing a method for manufacturing a wood laminate according to the second embodiment. 3A and 3B are schematic cross-sectional views showing a method for manufacturing a wood laminate according to a third embodiment. 4A to 4C are schematic cross-sectional views showing a method for manufacturing a wood laminate according to a fourth embodiment.

(1) Overview In recent years, the number of softwoods and hardwoods that can be used as decorative veneers has been decreasing. In this embodiment, a wood laminate 1 is provided that includes a decorative veneer that can be substituted for softwood and hardwood that have excellent aesthetic appearance.

The method for manufacturing the wood laminate 1 according to this embodiment includes a veneer manufacturing process, a catalyst supply process, and an adhesion process. In the veneer manufacturing process, sugar-containing veneer 4 is manufactured from plants containing sugar. In the catalyst supply step, a polyhydric carboxylic acid is supplied to the saccharide-containing veneer 4 to obtain the catalyst-containing veneer 7. In the bonding step, the catalyst-containing veneer 7 is stacked on both sides or one side of the core material 3, and a heat-pressure treatment is performed to bond the catalyst-containing veneer 7 and the core material 3 (see FIGS. 1A and 1B).

In the above manner, a wood laminate 1 as shown in FIG. 1B is obtained. The saccharide-containing veneer 4 passes through the catalyst-containing veneer 7 and becomes the surface layer 70 . The core material 3 becomes a core layer 30. As mentioned above, the sugar-containing veneer 4 ultimately forms the surface layer 70 of the wood laminate 1.

One of the features of this embodiment is that the sugar-containing veneer 4 is more easily compressed than the core material 3. Even when the saccharide-containing veneer 4 becomes the catalyst-containing veneer 7, it is more easily compressed than the core material 3. In the bonding process, when performing hot pressure treatment, the catalyst-containing veneer 7 is located between the heating plate of the hot press and the core material 3. Since the catalyst-containing veneer 7 is more easily compressed than the core material 3, pressure is intensively applied to the catalyst-containing veneer 7 when the heat-pressure treatment is performed. As a result, the catalyst-containing veneer 7 is highly compacted, making it difficult for moisture to penetrate. Therefore, in the wood laminate 1, it is possible to suppress moisture from penetrating from the surface layer 70 located on the surface to the core layer 30 located inside. Furthermore, since the surface layer 70 is highly consolidated, the surface hardness of the wood laminate 1 can also be improved. Furthermore, the surface texture of the wood laminate 1 becomes finer, and the appearance can be improved. Note that during the heat-pressing treatment, the core material 3 is also consolidated, but the degree of consolidation is lower than that of the catalyst-containing veneer 7.

As described above, according to the present embodiment, the wood laminate 1 having excellent water resistance can be manufactured without using a coniferous or hardwood veneer for the surface layer 70.

As mentioned above, one of the features of this embodiment is that the sugar-containing veneer 4 (catalyst-containing veneer 7) is more easily compressed than the core material 3. , the following problems may occur.

For example, if the sugar-containing veneer 4 (catalyst-containing veneer 7) and the core material 3 are easily compressed to the same extent, if the surface layer 70 is to be highly compacted, the core layer 30 must also be highly compacted. be. In this case, it is necessary to increase the pressure of the hot press, leading to an increase in the size of the manufacturing equipment, leading to concerns about an increase in manufacturing costs.

Furthermore, since both the surface layer 70 and the core layer 30 are highly consolidated, the weight of the wood laminate 1 tends to increase, making it difficult to handle the wood laminate 1.

Moreover, when trying to obtain a wood laminate 1 having the same thickness as the wood laminate 1 according to the present embodiment, the thickness of the core layer 30 is reduced by highly compacting the core layer 30. Therefore, the thickness of the core layer 30 must be adjusted in advance to account for this reduction. For example, when the core layer 30 is formed of a plurality of veneers, more veneers must be added in anticipation of the above reduction.

On the other hand, in this embodiment, the sugar-containing veneer 4 (catalyst-containing veneer 7) is more easily compressed than the core material 3, so the above problem is unlikely to occur.

(2) Details (2.1) First Embodiment FIG. 1B shows a wood laminate 1 according to this embodiment. The wood laminate 1 includes a surface layer 70 and a core layer 30. The surface layer 70 is adhered to both sides or one side of the core layer 30 (both sides in this embodiment). In the wood laminate 1, the surface layer 70 is the outer layer, and the core layer 30 is the inner layer.

The surface layer 70 is formed of the catalyst-containing single plate 7. The catalyst-containing veneer 7 is obtained by supplying the sugar-containing veneer 4 with a catalyst (polycarboxylic acid). In this way, the sugar-containing veneer 4 finally forms the surface layer 70 of the wood laminate 1. Note that the sugar-containing veneer 4 may form the core layer 30 of the wood laminate 1.

The method for manufacturing the wood laminate 1 according to this embodiment includes a veneer manufacturing process, a catalyst supply process, and an adhesion process. Each step of the method for manufacturing the wood laminate 1 will be described below.

≪Veneer manufacturing process≫
The veneer manufacturing process is a process of manufacturing saccharide-containing veneer 4 from a plant containing saccharides.

[Saccharide-containing veneer]
The saccharide-containing veneer 4 is a veneer obtained from a plant containing saccharides. Plants containing sugars are woody and have woody stems. The plant is preferably a palm, and among palms, oil palm and coconut palm are preferred. This is because palm contains a relatively large amount of sugar compared to other plants. This improves the water resistance and strength of the wood laminate 1.

The palm oil industry is thriving in Southeast Asia, but since palm trees stop producing fruit after 20 to 30 years, the problem is how to dispose of these old palm trees (OPT). This is because the burning of old trees is prohibited in order to prevent the release of greenhouse gases, and in addition, palms have a high moisture content, making it difficult to reuse them as wood. For this reason, it is desired to effectively utilize felled old palm trees and the like, and these can be easily obtained as raw materials for the wood laminate 1. In this manner, in this embodiment, if the plant is a palm tree, an old palm tree or the like can be effectively used.

The sugars contained in plants are monosaccharides, disaccharides, and polysaccharides (including oligosaccharides). Disaccharides and polysaccharides are composed of multiple monosaccharides linked together by glycosides. A plant may contain only one type of saccharide or two or more types of saccharide. The total content of monosaccharides and disaccharides is preferably 5% by mass or more based on the mass of the veneer (solid content).

Examples of monosaccharides include fructose, ribose, arabinose, rhamnose, xylulose, and deoxyribose.

Disaccharides include, for example, sucrose, maltose, trehalose, turanose, lactulose, maltulose, palatinose, gentiobiulose, melibiulose, galactosucrose, rutinulose, and planteobiose.

Polysaccharides include, for example, starch, agarose, alginic acid, glucomannan, inulin, chitin, chitosan, hyaluronic acid, glycogen and cellulose. Examples of oligosaccharides include fructooligosaccharides, galactooligosaccharides, mannan oligosaccharides, and stachyose.

A veneer (saccharide-containing veneer 4) is obtained from the above sugar-containing plant. The sugar-containing veneer 4 can be obtained by cutting a plant log using a cutting machine. Cutting machines include, for example, rotary races and slicers.

The thickness of the saccharide-containing veneer 4 is not particularly limited, but is, for example, within a range of 2 mm or more and 8 mm or less.

The density of the sugar-containing veneer 4 is not particularly limited, but is preferably in the range of 300 kg/m ³ or more and 500 kg/m ³ or less, more preferably in the range of 350 kg/m ³ or more and 450 kg/m ³ or less. .

≪Catalyst supply process≫
The catalyst supply step is a step in which a polycarboxylic acid is supplied to the saccharide-containing veneer 4 to obtain the catalyst-containing veneer 7.

[Catalyst-containing veneer]
The catalyst-containing veneer 7 is a veneer in which a polycarboxylic acid is supplied as a catalyst to the saccharide-containing veneer 4. The catalyst-containing veneer 7 contains sugars and polycarboxylic acids.

The polyhydric carboxylic acid is not particularly limited as long as it is a compound having multiple carboxy groups. Examples of polycarboxylic 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, glutaric acid (1 , 5-pentanedioic acid), glutaconic acid and pentenedioic acid. Acid anhydrides can also be used as polyhydric carboxylic acids.

Among the polyhydric carboxylic acids listed above, citric acid, tartaric acid, malic acid, gluconic acid, sebacic acid, and itaconic acid are particularly preferred because they can be produced using plants as raw materials. When plants are used as raw materials in this way, the use of fossil resources is suppressed, so the wood laminate 1 can be obtained without placing a burden on the environment. Note that polyhydric carboxylic acid has the same meaning as polycarboxylic acid.

Preferably, the polycarboxylic acid is supplied as a polycarboxylic acid solution (for example, a polycarboxylic acid aqueous solution). This makes it easier for the polycarboxylic acid to be impregnated into the saccharide-containing veneer 4. As a result, the water resistance of the wood laminate 1 can be further improved.

Specifically, the polyhydric carboxylic acid can be supplied to the sugar-containing veneer 4 as follows. That is, the polycarboxylic acid aqueous solution can be sprayed onto the sugar-containing veneer 4 using a spray or the like. Furthermore, the saccharide-containing veneer 4 can be immersed in an aqueous polycarboxylic acid solution. Further, the polyhydric carboxylic acid aqueous solution can be applied to the sugar-containing veneer 4 using a roll or a brush. Further, the polyhydric carboxylic acid powder can be directly sprinkled onto the sugar-containing veneer 4.

As described above, when supplying the polycarboxylic acid to the sugar-containing veneer 4, the polycarboxylic acid may be in the form of an aqueous solution or a powder. When in the form of an aqueous solution, the concentration of the aqueous polyhydric carboxylic acid solution is not particularly limited, but is, for example, in the range of 1% by mass to 50% by mass.

The amount of polyhydric carboxylic acid supplied is not particularly limited. The amount of polycarboxylic acid supplied is defined, for example, by the mass of polycarboxylic acid present per unit volume of the sugar-containing veneer 4. Preferably, the amount of polyhydric carboxylic acid supplied is within the range of 0.5% by mass or more and 5% by mass or less in solid content ratio.

≪Adhesion process≫
1A and 1B show the bonding process. In the adhesion process, the catalyst-containing veneer 7 is stacked on both sides or one side of the core material 3 (both sides in this embodiment), and a heat pressure treatment (hot press) is performed to bond the catalyst-containing veneer 7 and the core material 3. It is a process. Thereby, the catalyst-containing veneer 7 and the core material 3 are integrated, and a wood laminate 1 as shown in FIG. 1B is obtained.

Here, as shown in FIG. 1A, the core material 3 includes a plurality of sugar-containing veneers 4. A plurality of sugar-containing veneers 4 are laminated. A polyhydric carboxylic acid or an adhesive is supplied to a plurality of saccharide-containing veneers 4. Before performing the heat and pressure treatment, the plurality of saccharide-containing veneers 4 included in the core material 3 are not yet bonded together. In addition, below, the sugar-containing veneer 4 located at the outermost position in the core material 3 may be referred to as the outermost veneer 40.

The fiber direction (direction of wood grain) of each of the plurality of saccharide-containing veneers 4 included in the core material 3 is not particularly limited. The fiber directions of adjacent sugar-containing veneers 4 may be non-parallel or parallel. The fiber directions of the sugar-containing veneer 4 (catalyst-containing veneer 7) serving as the surface layer 70 and the outermost veneer 40 may be non-parallel or parallel. Note that in this specification, non-parallel includes orthogonal.

When polyhydric carboxylic acid is supplied to a plurality of saccharide-containing veneers 4 included in the core material 3, these saccharide-containing veneers 4 become catalyst-containing veneers 7. The method for supplying the polycarboxylic acid to the sugar-containing veneer 4 and the catalyst-containing veneer 7 are as described above. By supplying the polycarboxylic acid to the saccharide-containing veneer 4, the reaction product of the saccharide and the polycarboxylic acid can function as an adhesive.

On the other hand, the adhesive may be supplied to a plurality of saccharide-containing veneers 4. Examples of the adhesive include, but are not limited to, urea-melamine adhesives and phenolic adhesives. The method for supplying the adhesive is not particularly limited, but includes, for example, coating.

The amount of adhesive supplied (amount of application) is not particularly limited. The supply amount of the adhesive is defined, for example, by the mass of the adhesive present per unit area of the sugar-containing veneer 4. Preferably, the amount of adhesive supplied is in the range of 200 g/m ² or more and 500 g/m ² or less.

The peel strength of the wood laminate 1 can be improved by supplying either the polycarboxylic acid or the adhesive to the plurality of saccharide-containing veneers 4 included in the core material 3.

One of the features of this embodiment is that the sugar-containing veneer 4 (catalyst-containing veneer 7) serving as the surface layer 70 is more easily compressed than the core material 3 serving as the core layer 30. Even when the saccharide-containing veneer 4 becomes the catalyst-containing veneer 7, it is more easily compressed than the core material 3. In particular, when the core material 3 includes a plurality of saccharide-containing veneers 4, the saccharide-containing veneer 4 (catalyst-containing veneer 7) serving as the surface layer 70 is more likely to be compressed than the outermost veneer 40 adjacent thereto. .

Compressibility can be compared based on the density after compression when two test specimens are compressed in the thickness direction with the same pressure. A specimen with a higher density after compression is more likely to be compressed. This compressibility can be adjusted by the moisture content of the two test specimens being compared. A specimen with a higher moisture content is more likely to be compressed. Therefore, by making the moisture content of the saccharide-containing veneer 4 that forms the surface layer 70 higher than the moisture content of the core material 3, the saccharide-containing veneer 4 can be made more compressible than the core material 3. Thereby, the saccharide-containing veneer 4 becomes more compressible than the core material 3. The moisture content can be adjusted by adjusting drying conditions (temperature, time, etc.) or by humidification.

Moisture content can be calculated as follows. First, the mass (W ₁ : mass before drying) of two test pieces to be compared is measured. Next, these are dried at 103±2° C. in a dryer, and the mass (W ₂ : total dry mass) when it is recognized that a constant weight has been reached is measured. Then, the moisture content of the two test pieces can be calculated using the following equation (1).

It is advantageous for the saccharide-containing veneer 4 (catalyst-containing veneer 7), which forms the surface layer 70, to be compressed more easily than the core material 3, which forms the core layer 30, for the following reasons. In the bonding process, when performing hot pressure treatment, the catalyst-containing veneer 7 is located between the heating plate of the hot press and the core material 3. As described above, the catalyst-containing veneer 7 is more easily compressed than the core material 3, so when the heat-pressure treatment is performed, pressure is intensively applied to the catalyst-containing veneer 7. At this time, the core material 3 is also compressed, but the catalyst-containing veneer 7 sandwiched between the core material 3 and the hot plate is compressed more than the core material 3. As a result, the catalyst-containing veneer 7 is highly compacted, making it difficult for moisture to penetrate. Therefore, in the wood laminate 1, it is possible to suppress moisture from penetrating from the surface layer 70 located on the surface to the core layer 30 located inside. Furthermore, since the surface layer 70 is highly consolidated, the surface hardness of the wood laminate 1 can also be improved. Furthermore, the surface texture of the wood laminate 1 becomes finer, and the appearance can be improved.

Therefore, according to this embodiment, the wood laminate 1 having excellent water resistance can be manufactured without using a coniferous or hardwood veneer for the surface layer 70.

The heat and pressure treatment will be explained below. Heat-pressure treatment is a process of compressing while heating. In the heat-pressing treatment, a known pressing device (press) can be used. Heat sources include, but are not limited to, steam, hot water, electric heat, and high frequency. Examples of the press method include, but are not particularly limited to, a flat plate (single-stage, multi-stage) press method and a roll (continuous) press method.

The temperature of the heat-pressure treatment is not particularly limited, but is, for example, in the range of 140°C or higher and 230°C or lower. The pressure of the hot pressure treatment is preferably in the range of 0.5 MPa or more and 4 MPa or less. The higher the pressure within this range, the more the surface smoothness of the wood laminate 1 can be improved. The time for the heat-pressure treatment is preferably in the range of 10 seconds or more and 30 minutes or less.

Here, the curing reaction that occurs within the catalyst-containing veneer 7 during the heat-pressure treatment will be explained. A curing reaction means a reaction between a saccharide and a polycarboxylic acid. It is presumed that when the catalyst-containing veneer 7 is heat-treated, it undergoes a two-step reaction and is completely cured.

That is, the first stage reaction progresses by heat treatment, and the second stage reaction progresses and is completed by further heat treatment. The catalyst-containing veneer 7 becomes a cured product upon completion of the second stage reaction. As the second stage reaction approaches, the reaction product of sugar and polycarboxylic acid (for example, sugar citric acid reaction product) becomes thermosetting. By curing this reactant, the fibers inside the catalyst-containing veneer 7 are bonded together. Note that in this specification, the reactant includes a substance before reaction and a substance (product) after reaction.

In the first stage of the reaction, sugars contained in plants are hydrolyzed and hydrolyzed products are produced. Furthermore, the hydrolysis product undergoes dehydration condensation to produce a reaction product of a sugar-modified product. The condensation water generated at this time is removed by an appropriate method.

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

The step of applying pressure is not particularly limited. For example, pressurization may be carried out from the start of the first stage to the end of the second stage, or may be carried out from the start of the second stage to the end of the second stage without being applied in the first stage.

(2.2) Second Embodiment In the second embodiment, components similar to those in the first embodiment may be given the same reference numerals as those in the first embodiment, and detailed description thereof may be omitted.

The method for manufacturing the wood laminate 1 according to this embodiment includes a veneer manufacturing process, a catalyst supply process, and an adhesion process. Preferably, the method for manufacturing the wood laminate 1 further includes a polishing step. The veneer manufacturing process and catalyst supply process are the same as in the first embodiment. In the first embodiment, the bonding step is performed only once, but in this embodiment, the bonding step is divided into two steps.

≪Adhesion process≫
The bonding process is roughly divided into a first bonding process (FIGS. 2A to 2B) and a second bonding process (FIGS. 2B to 2C).

[First adhesion process]
The first bonding step is a step in which a plurality of saccharide-containing veneers 4 are stacked and bonded to obtain the core material 3. An adhesive or polycarboxylic acid is supplied to the plurality of sugar-containing veneers 4. For example, an adhesive or a polycarboxylic acid is interposed between adjacent sugar-containing veneers 4.

Here, the subsequent processing is different depending on whether the adhesive is supplied to a plurality of saccharide-containing veneers 4 or the polyhydric carboxylic acid is supplied to a plurality of saccharide-containing veneers 4, so the cases will be explained separately below. I will explain.

First, a case in which adhesive is supplied to a plurality of saccharide-containing veneers 4 will be described. In this case, in the first bonding step, cold pressing and hot pressing are performed. Cold pressing is a process of pressing at room temperature without heating. The heat and pressure treatment is as described above. In this way, a plurality of saccharide-containing veneers 4 are integrated by the cold pressure treatment and hot pressure treatment, and the core material 3 as the plate material 6 is obtained.

This will be explained in more detail. First, a plurality of saccharide-containing veneers 4 are stacked to form a laminate. At this time, adhesive is supplied to the plurality of sugar-containing veneers 4. The fiber direction of each of the plurality of saccharide-containing veneers 4 is not particularly limited. The fiber directions of adjacent sugar-containing veneers 4 may be non-parallel or parallel.

Next, the above laminate is subjected to cold pressure treatment. As a result, the plurality of saccharide-containing veneers 4 are temporarily bonded. In the cold pressure treatment, a known compaction device can be used. Examples of the press method include, but are not particularly limited to, a flat plate (single-stage, multi-stage) press method and a roll (continuous) press method.

The pressure of the cold pressure treatment is not particularly limited, but is, for example, within a range of 0.5 MPa or more and 4 MPa or less. The time for the cold pressure treatment is not particularly limited, but is, for example, in the range of 10 seconds or more and 20 minutes or less.

Next, the laminate after the cold pressure treatment is subjected to a hot pressure treatment. Thereby, the core material 3 as the plate material 6 is obtained. The plate material 6 includes plywood and/or laminated veneer material. As a result, various wood laminates 1 can be obtained depending on the type of board material 6.

The temperature of the heat-pressure treatment is not particularly limited, but when the adhesive is supplied to a plurality of saccharide-containing veneers 4 as described above, it is preferably in the range of 80 ° C. or more and 150 ° C. or less, and more preferably It is within the range of 105°C or more and 150°C or less. The pressure of the heat-pressure treatment is not particularly limited, but is, for example, within a range of 0.5 MPa or more and 4 MPa or less. The time for the heat-pressure treatment is not particularly limited, but is, for example, in the range of 10 seconds or more and 15 minutes or less.

Next, a case in which polyhydric carboxylic acid is supplied to a plurality of saccharide-containing veneers 4 will be described. In this case, in the first bonding step, only hot pressure treatment is performed without performing cold pressure treatment. The heat and pressure treatment is as described above. In this way, a plurality of saccharide-containing veneers 4 are integrated by the heat-pressing treatment, and the core material 3 as the plate material 6 is obtained.

This will be explained in more detail. First, a plurality of saccharide-containing veneers 4 are stacked to form a laminate. At this time, polyhydric carboxylic acid is supplied to the plurality of saccharide-containing veneers 4. The fiber direction of each of the plurality of saccharide-containing veneers 4 is not particularly limited. The fiber directions of adjacent sugar-containing veneers 4 may be non-parallel or parallel.

Next, the above laminate is subjected to heat-pressure treatment. Thereby, the core material 3 as the plate material 6 is obtained. The plate material 6 includes plywood and/or laminated veneer material. As a result, various wood laminates 1 can be obtained depending on the type of board material 6.

The temperature of the heat-pressure treatment is not particularly limited, but when the polycarboxylic acid is supplied to a plurality of saccharide-containing veneers 4 as described above, it is preferably in the range of 140°C or higher and 230°C or lower. The pressure of the heat-pressure treatment is not particularly limited, but is, for example, within a range of 0.5 MPa or more and 4 MPa or less. The time for the heat-pressure treatment is not particularly limited, but is, for example, in the range of 10 seconds or more and 15 minutes or less.

[Second adhesion process]
The second bonding step is a step of bonding the catalyst-containing veneer 7 to both sides or one side of the core material 3 as the plate material 6 obtained in the first bonding step. In the second adhesion step, only heat-pressure treatment (second time) is performed.

First, the core material 3 and the catalyst-containing veneer 7 are stacked to form a laminate. In FIG. 2B, catalyst-containing veneer plates 7 are arranged on both sides of core material 3, but catalyst-containing veneer plates 7 may be arranged only on one side of core material 3.

The fiber directions of the outermost veneer 40 located on the surface of the core material 3 and the catalyst-containing veneer 7 may be non-parallel or parallel.

Next, the above laminate is subjected to heat-pressure treatment. As a result, a wood laminate 1 is obtained.

The temperature of the heat-pressure treatment is not particularly limited, but is preferably in the range of 140°C or higher and 230°C or lower. The pressure of the heat-pressure treatment is not particularly limited, but is, for example, within a range of 0.5 MPa or more and 4 MPa or less. The time for the heat-pressure treatment is not particularly limited, but is, for example, in the range of 10 seconds or more and 30 minutes or less.

In this embodiment as well, since the sugar-containing veneer 4 (catalyst-containing veneer 7), which forms the surface layer 70, is more easily compressed than the core material 3, when the heat-pressure treatment is performed, the catalyst-containing veneer 7 is concentrated. Pressure is applied. At this time, the core material 3 is also compressed, but the catalyst-containing veneer 7 sandwiched between the core material 3 and the hot plate is compressed more than the core material 3. As a result, the catalyst-containing veneer 7 is highly compacted, making it difficult for moisture to penetrate. Therefore, in the wood laminate 1, it is possible to suppress moisture from penetrating from the surface layer 70 located on the surface to the core layer 30 located inside. Furthermore, since the surface layer 70 is highly consolidated, the surface hardness of the wood laminate 1 can also be improved. Furthermore, the surface texture of the wood laminate 1 becomes finer, and the appearance can be improved.

Therefore, according to this embodiment, the wood laminate 1 having excellent water resistance can be manufactured without using a coniferous or hardwood veneer for the surface layer 70.

≪Polishing process≫
The polishing process is located between the first bonding process and the second bonding process. The polishing step is a step of polishing both or one side of the core material 3 as the plate material 6 obtained in the first bonding step. The catalyst-containing veneer 7 is stacked on the polished surface of the core material 3. In this way, by polishing the surface of the core material 3 on which the catalyst-containing veneer 7 is stacked, the adhesion between the surface layer 70 and the core layer 30 can be improved. Therefore, the peel strength of the wood laminate 1 can be improved.

For sanding, known coated abrasive paper (abrasive cloth and abrasive paper) can be used. The material and particle size of the abrasive used in the coated abrasive paper are not particularly limited.

(2.3) Third Embodiment In the third embodiment, the same components as in the first to second embodiments are given the same reference numerals as in the first to second embodiments, and detailed explanations may be omitted. be.

The method for manufacturing the wood laminate 1 according to this embodiment includes a veneer manufacturing process, a catalyst supply process, and an adhesion process. The veneer manufacturing process and catalyst supply process are the same as in the first embodiment. This embodiment and the first embodiment differ in the core material 3 used in the bonding process.

≪Adhesion process≫
3A and 3B show the bonding process. In the adhesion process, the catalyst-containing veneer 7 is stacked on both sides or one side of the core material 3 (both sides in this embodiment), and a heat pressure treatment (hot press) is performed to bond the catalyst-containing veneer 7 and the core material 3. It is a process. Thereby, the catalyst-containing veneer 7 and the core material 3 are integrated, and a wood laminate 1 as shown in FIG. 3B is obtained.

Here, as shown in FIG. 3A, the core material 3 includes a plurality of veneers 5. The veneer 5 in this case is not particularly limited. The veneer 5 may be the saccharide-containing veneer 4 or a veneer other than the saccharide-containing veneer 4. The veneer 5 may be a veneer obtained from a coniferous tree (for example, cedar) or a veneer obtained from a hardwood (for example, lauan). A plurality of veneers 5 are laminated. Adhesive is supplied to the plurality of veneers 5. Before performing the heat-pressure treatment, the plurality of veneers 5 included in the core material 3 are not yet bonded together. In addition, below, the veneer 5 located at the outermost position in the core material 3 may be referred to as the outermost veneer 50.

The fiber direction (direction of wood grain) of each of the plurality of veneers 5 included in the core material 3 is not particularly limited. The fiber directions of adjacent veneers 5 may be non-parallel or parallel. The fiber directions of the sugar-containing veneer 4 (catalyst-containing veneer 7) serving as the surface layer 70 and the outermost veneer 50 may be non-parallel or parallel.

The adhesive supplied to the plurality of veneers 5 is not particularly limited, and examples thereof include urea-melamine adhesive and phenolic adhesive. The method for supplying the adhesive is not particularly limited, but includes, for example, coating.

The amount of adhesive supplied (amount of application) is not particularly limited. The amount of adhesive supplied is defined, for example, by the mass of adhesive present per unit area of the veneer 5. Preferably, the amount of adhesive supplied is in the range of 200 g/m ² or more and 500 g/m ² or less.

When the adhesive is supplied to the plurality of veneers 5 included in the core material 3, the peel strength of the wood laminate 1 can be improved.

In this embodiment as well, since the sugar-containing veneer 4 (catalyst-containing veneer 7), which forms the surface layer 70, is more easily compressed than the core material 3, when the heat-pressure treatment is performed, the catalyst-containing veneer 7 is concentrated. Pressure is applied. At this time, the core material 3 is also compressed, but the catalyst-containing veneer 7 sandwiched between the core material 3 and the hot plate is compressed more than the core material 3. As a result, the catalyst-containing veneer 7 is highly compacted, making it difficult for moisture to penetrate. Therefore, in the wood laminate 1, it is possible to suppress moisture from penetrating from the surface layer 70 located on the surface to the core layer 30 located inside. Furthermore, since the surface layer 70 is highly consolidated, the surface hardness of the wood laminate 1 can also be improved. Furthermore, the surface texture of the wood laminate 1 becomes finer, and the appearance can be improved.

Therefore, according to this embodiment, the wood laminate 1 having excellent water resistance can be manufactured without using a coniferous or hardwood veneer for the surface layer 70.

(2.4) Fourth Embodiment In the fourth embodiment, the same components as in the first to third embodiments are given the same reference numerals as those in the first to third embodiments, and detailed explanations may be omitted. be.

The method for manufacturing the wood laminate 1 according to this embodiment includes a veneer manufacturing process, a catalyst supply process, and an adhesion process. Preferably, the method for manufacturing the wood laminate 1 further includes a polishing step. The veneer manufacturing process and catalyst supply process are the same as in the first embodiment. The adhesion process is almost the same as the second embodiment, but the core material 3 used in the adhesion process is different between this embodiment and the second embodiment. The polishing process is the same as in the second embodiment.

≪Adhesion process≫
The bonding process is roughly divided into a first bonding process (FIGS. 4A to 4B) and a second bonding process (FIGS. 4B to 4C).

[First adhesion process]
The first bonding step is a step in which a plurality of veneers 5 are stacked and bonded to obtain the core material 3. The veneer 5 is the same as in the third embodiment. In the first bonding step, cold pressure treatment and hot pressure treatment are performed. The cold pressure treatment and hot pressure treatment are as described above. In this way, the plurality of veneers 5 are integrated by the cold pressure treatment and the hot pressure treatment, and the core material 3 as the plate material 6 is obtained.

First, a plurality of veneers 5 are stacked to form a laminate. At this time, adhesive is supplied to the plurality of veneers 5. Specifically, an adhesive is interposed between adjacent veneers 5. The fiber direction of each of the plurality of veneers 5 is not particularly limited. The fiber directions of adjacent veneers 5 may be non-parallel or parallel.

Next, the above laminate is subjected to cold pressure treatment. As a result, the plurality of veneers 5 are temporarily bonded. In the cold pressure treatment, a known compaction device can be used. Examples of the press method include, but are not particularly limited to, a flat plate (single-stage, multi-stage) press method and a roll (continuous) press method.

The pressure of the cold pressure treatment is not particularly limited, but is, for example, within a range of 0.5 MPa or more and 4 MPa or less. The time for the cold pressure treatment is not particularly limited, but is, for example, in the range of 10 seconds or more and 20 minutes or less.

Next, the laminate after the cold pressure treatment is subjected to a hot pressure treatment. Thereby, the core material 3 as the plate material 6 is obtained. The plate material 6 includes plywood and/or laminated veneer material. As a result, various wood laminates 1 can be obtained depending on the type of board material 6.

The temperature of the heat-pressure treatment is not particularly limited, but is preferably in the range of 80°C or higher and 150°C or lower, more preferably in the range of 105°C or higher and 150°C or lower. The pressure of the heat-pressure treatment is not particularly limited, but is, for example, within a range of 0.5 MPa or more and 4 MPa or less. The time for the heat-pressure treatment is not particularly limited, but is, for example, in the range of 10 seconds or more and 15 minutes or less.

[Second adhesion process]
The second bonding step is a step of bonding the catalyst-containing veneer 7 to both or one side of the core material 3 obtained in the first bonding step. In the second adhesion step, only heat-pressure treatment (second time) is performed.

First, the core material 3 and the catalyst-containing veneer 7 are stacked to form a laminate. In FIG. 4B, the catalyst-containing veneer 7 is arranged on both sides of the core material 3, but the catalyst-containing veneer 7 may be arranged only on one side of the core material 3.

The fiber directions of the outermost veneer 50 and the catalyst-containing veneer 7 located on the surface of the core material 3 may be non-parallel or parallel.

Next, the above laminate is subjected to heat-pressure treatment. As a result, a wood laminate 1 is obtained.

The temperature of the heat-pressure treatment is not particularly limited, but is preferably in the range of 140°C or higher and 230°C or lower. The pressure of the heat-pressure treatment is not particularly limited, but is, for example, within a range of 0.5 MPa or more and 4 MPa or less. The time for the heat-pressure treatment is not particularly limited, but is, for example, in the range of 10 seconds or more and 30 minutes or less.

In this embodiment as well, since the sugar-containing veneer 4 (catalyst-containing veneer 7), which forms the surface layer 70, is more easily compressed than the core material 3, when the heat-pressure treatment is performed, the catalyst-containing veneer 7 is concentrated. Pressure is applied. At this time, the core material 3 is also compressed, but the catalyst-containing veneer 7 sandwiched between the core material 3 and the hot plate is compressed more than the core material 3. As a result, the catalyst-containing veneer 7 is highly compacted, making it difficult for moisture to penetrate. Therefore, in the wood laminate 1, it is possible to suppress moisture from penetrating from the surface layer 70 located on the surface to the core layer 30 located inside. Furthermore, since the surface layer 70 is highly consolidated, the surface hardness of the wood laminate 1 can also be improved. Furthermore, the surface texture of the wood laminate 1 becomes finer, and the appearance can be improved.

Therefore, according to this embodiment, the wood laminate 1 having excellent water resistance can be manufactured without using a coniferous or hardwood veneer for the surface layer 70.

(3) Modification In the fourth embodiment, a commercially available plate material is used instead of the core material 3 obtained in the first bonding process, the first bonding process is omitted, and only the second bonding process is performed. You can do it like this.

The above-mentioned board materials include board materials obtained from coniferous trees and board materials obtained from hardwoods.

Furthermore, the above board materials include plywood, veneer laminate (LVL), and lumber core plywood.

(4) Aspect The first aspect is a method for manufacturing a wood laminate (1), which includes a veneer manufacturing process, a catalyst supply process, and an adhesion process. In the veneer manufacturing process, a saccharide-containing veneer (4) is manufactured from a plant containing saccharides. In the catalyst supply step, a polyhydric carboxylic acid is supplied to the saccharide-containing veneer (4) to obtain a catalyst-containing veneer (7). In the bonding step, the catalyst-containing veneer (7) is stacked on both sides or one side of the core material (3), and heat-pressure treatment is performed to bond the catalyst-containing veneer (7) and the core material (3). do. The sugar-containing veneer (4) is more easily compressed than the core material (3).

According to this aspect, a wood laminate (1) with excellent water resistance can be manufactured without using a coniferous or hardwood veneer for the surface layer.

The second aspect is a method for manufacturing a wood laminate (1) based on the first aspect. In the second aspect, the moisture content of the saccharide-containing veneer (4) is higher than the moisture content of the core material (3).

According to this aspect, the saccharide-containing veneer (4) is more easily compressed than the core material (3).

The third aspect is a method for manufacturing a wood laminate (1) based on the first or second aspect. In a third aspect, the core material (3) includes a plurality of the sugar-containing veneers (4). A polyhydric carboxylic acid or an adhesive is supplied to the plurality of saccharide-containing veneers (4).

According to this aspect, the peel strength of the wood laminate (1) can be improved.

A fourth aspect is a method for manufacturing a wood laminate (1) based on the first or second aspect. In a fourth aspect, the core material (3) includes a plurality of veneers (5). An adhesive is supplied to the plurality of veneers (5).

According to this aspect, the peel strength of the wood laminate (1) can be improved.

A fifth aspect is a method for manufacturing a wood laminate (1) based on the first or second aspect. In a fifth aspect, the core material (3) includes a plate material (6). The board material (6) includes plywood and/or laminated veneer material.

According to this aspect, various wood laminates (1) can be obtained depending on the type of board (6).

A sixth aspect is a method for manufacturing a wood laminate (1) based on any one of the first to fifth aspects. In a sixth aspect, the surface of the core material (3) on which the catalyst-containing veneer (7) is stacked is polished.

According to this aspect, the peel strength of the wood laminate (1) can be improved.

Hereinafter, the present disclosure will be specifically explained using examples. However, the present disclosure is not limited to the examples.

(Example 1)
<Saccharide-containing veneer>
Coconut veneer (OPT) was used as the sugar-containing veneer. The thickness and density of the sugar-containing veneer are shown in the surface layer column of Table 1.

<Catalyst-containing veneer>
A catalyst (citric acid aqueous solution with a concentration of 3% by mass) was applied to both sides of the sugar-containing veneer to obtain a catalyst-containing veneer. The catalyst was applied in an adjusted amount of 1% by mass based on the total mass (solid content) of the catalyst and the coconut veneer. Thereafter, the catalyst-containing veneer was dried at 80° C. to adjust the moisture content to 10% by mass.

<Core material>
Coconut veneer (OPT) was used as the sugar-containing veneer. The thickness, density, and number of core layers of the sugar-containing veneer are shown in the core layer column of Table 1.

Next, a catalyst (citric acid aqueous solution with a concentration of 8% by mass) was applied to both sides of the sugar-containing veneer. The catalyst was applied in an adjusted amount of 3% by mass based on the total mass (solid content) of the catalyst and the coconut veneer. Thereafter, the saccharide-containing veneer coated with the catalyst was dried at 80°C to adjust the moisture content to 3% by mass or less.

<Wood laminate>
Next, catalyst-containing veneers were stacked on both sides of the core material and subjected to hot pressure treatment using a pressing device. Table 2 shows the conditions for the heat and pressure treatment. Note that a distance bar was attached between the upper and lower hot plates of the pressing device, and by setting the distance between the distance bars to 12 mm, the thickness of the wood laminate was kept constant (12 mm).

A wood laminate was manufactured as described above. Table 2 shows the thickness and density of the wood laminate.

(Example 2)
A wood laminate was produced in the same manner as in Example 1, except that the moisture content of the catalyst-containing veneer used for the surface layer was changed to 12% by mass by adjusting the drying time.

(Example 3)
A wood laminate was produced in the same manner as in Example 2, except that the conditions of the heat-pressure treatment were changed.

(Example 4)
<Saccharide-containing veneer>
This is the same as in Example 1.

<Catalyst-containing veneer>
This is the same as in Example 1.

<Core material>
The same coconut veneer (OPT) as in Example 1 was used as the sugar-containing veneer. Adhesive was applied to both sides of the sugar-containing veneer. A urea melamine adhesive was used as the adhesive. The amount of adhesive applied is shown in the core layer column of Table 1.

Next, five of the above sugar-containing veneers were stacked and subjected to cold pressure treatment and hot pressure treatment using a pressing device to produce a core material as a plate material. The conditions for the cold pressure treatment and hot pressure treatment are the same as in Comparative Example 2. When performing cold pressure treatment and hot pressure treatment, the thickness of the core material was kept constant (9 mm) by setting the distance between the distance bars to 9 mm. The thickness, density, number of layers, and moisture content of the obtained core material are shown in the core layer column of Table 1. Furthermore, both sides of the core material were polished. The grit of the coated abrasive paper is shown in the sanding column of Table 1.

<Wood laminate>
A wood laminate was produced in the same manner as in Example 1, except that the above core material was used in place of the core material in Example 1, and the conditions (time) of the heat-pressure treatment were changed.

(Example 5)
A wood laminate was produced in the same manner as in Example 4, except that both sides of the core material were not polished.

(Example 6)
<Saccharide-containing veneer>
This is the same as in Example 1.

<Catalyst-containing veneer>
This is the same as in Example 1.

<Core material>
Commercially available softwood plywood was used as the core material. The thickness and moisture content of this softwood plywood are shown in the core layer column of Table 1. Both sides of the softwood plywood were polished. The grit of the coated abrasive paper is shown in the sanding column of Table 1. Adhesive was applied to both sides of the softwood plywood. A urea melamine adhesive was used as the adhesive. The amount of adhesive applied is shown in the core layer column of Table 1.

<Wood laminate>
A wood laminate was produced in the same manner as in Example 4, except that the above core material was used instead of the core material in Example 4.

(Comparative example 1)
A wood laminate was produced in the same manner as in Example 1, except that the moisture content of the catalyst-containing veneer used for the surface layer was changed to 3% by mass or less (same as the moisture content of the core material) by adjusting the drying time. did.

(Comparative example 2)
Coconut veneer (OPT) was used as the sugar-containing veneer. The thickness, density, number of layers, and moisture content of the sugar-containing veneer are shown in the core layer column of Table 1. Adhesive was applied to both sides of the sugar-containing veneer. A urea melamine adhesive was used as the adhesive. The amount of adhesive applied is shown in the core layer column of Table 1.

Next, seven saccharide-containing veneers described above were stacked and subjected to cold pressure treatment and hot pressure treatment using a pressing device to produce a wood laminate. Table 2 shows the conditions for the cold pressure treatment and hot pressure treatment. When performing the cold pressure treatment and the hot pressure treatment, the distance between the distance bars was set to 12 mm, so that the thickness of the wood laminate was kept constant (12 mm).

(Comparative example 3)
<Core material>
This is the same as in Example 4.

<Wood laminate>
Next, MLH (Mixed Light Hardwoods) was layered on both sides of the above-mentioned core material via a urea-melamine adhesive, and cold pressure treatment and hot pressure treatment were performed using a pressing device. MLH is a veneer obtained from hardwood that has been conventionally used as a decorative veneer. Table 2 shows the conditions for the cold pressure treatment and hot pressure treatment. A wood laminate was produced in this way.

<Performance evaluation>
[Smoothness]
In order to evaluate the smoothness, the arithmetic mean roughness (Ra) of the surface of the wood laminate was measured. Performance was evaluated based on the following criteria.

A: Arithmetic mean roughness (Ra) is 3.2 μm or less B: Arithmetic mean roughness (Ra) is more than 3.2 μm and less than 6.3 μm C: Arithmetic mean roughness (Ra) is more than 6.3 μm.

[Surface hardness (weight drop resistance)]
In order to evaluate the surface hardness, a DuPont test was conducted on the wood laminate in accordance with JIS K 5600-5-3. A 500 g weight with a round tip was dropped onto the surface of the wood laminate from a height of 30 cm with the tip facing down. The tip diameter of the weight is 0.5 inches (about 1.27 cm). The depth of the depression formed by the collision of the weights was measured. Performance was evaluated based on the following criteria.

A: The depth of the dent is 0.2 mm or less B: The depth of the dent is more than 0.2 mm and 0.3 mm or less C: The depth of the dent is more than 0.3 mm and 0.5 mm or less D: The depth of the dent is 0. More than 5 mm and less than 0.8 mm E: The depth of the dent is more than 0.8 mm.

[Water resistance (water absorption thickness expansion rate)]
In order to evaluate water resistance, a water absorption thickness expansion test was conducted on the wood laminate in accordance with JIS A 5908. Performance was evaluated based on the following criteria.

A: Water absorption thickness expansion rate is 3% or less B: Water absorption thickness expansion rate is more than 3% and 5% or less C: Water absorption thickness expansion rate is more than 5% and 12% or less D: Water absorption thickness expansion rate is more than 12% .

[Peel strength]
In order to evaluate the strength, a peel strength test was conducted in accordance with JIS A 5908. Performance was evaluated based on the following criteria.

A: Peel strength is 0.4 MPa or more. B: Peel strength is less than 0.4 MPa.

1 Wood laminate 3 Core material 4 Saccharide-containing veneer 5 Veneer 6 Board material 7 Catalyst-containing veneer

Claims (5)

A veneer production process for producing sugar-containing veneers from sugar-containing plants;
a catalyst supply step of supplying a polycarboxylic acid to the sugar-containing veneer to obtain a catalyst-containing veneer;
an adhesion step of stacking the catalyst -containing veneer having a water content higher than that of the core material on both sides or one side of the core material , and performing a heat-pressure treatment to bond the catalyst-containing veneer and the core material; including;
the sugar-containing veneer is more easily compressed than the core material;
Method for manufacturing wood laminates. The core material includes a plurality of the sugar-containing veneers,
A polyhydric carboxylic acid or an adhesive is supplied to the plurality of saccharide-containing veneers,
A method for manufacturing a wood laminate according to claim 1 . The core material includes a plurality of veneers,
Adhesive is supplied to the plurality of veneers;
A method for manufacturing a wood laminate according to claim 1 . The core material includes a plate material,
The board material includes plywood and/or laminated veneer material,
A method for manufacturing a wood laminate according to claim 1 . the surface of the core material on which the catalyst-containing veneer is stacked is polished;
A method for producing a wood laminate according to any one of claims 1 to 4 .

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