JP2016222843A - Thermosetting adhesive and molded sheet using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a powdery thermosetting adhesive capable of being dispersed uniformly in plant pieces regardless of temperature condition and further excellent in adhesiveness.SOLUTION: A powdery thermosetting adhesive contains saccharide and camphorsulfonic acid. A molded sheet contains the thermosetting adhesive and a plurality of plant pieces adhered by the thermosetting adhesive. Because the camphorsulfonic acid has low hygroscopic property, it can be dispersed uniformly in the plant pieces regardless of temperature condition. Because the saccharide and the camphorsulfonic acid have high reaction speed, molding time can be reduced and adhesiveness can be enhanced.SELECTED DRAWING: None

Description

  The present invention relates to a thermosetting adhesive and a molded plate using the same. Specifically, the present invention relates to a powdery thermosetting adhesive excellent in adhesiveness, and a molded plate using the thermosetting adhesive.

  As woody adhesives, those derived from biomass such as casein, soybean glue, and glue have been known since ancient times. However, these have poor physical properties such as adhesiveness, and have recently been replaced with petroleum-derived thermosetting resin adhesives such as urea, melamine, and phenol. Then, with these adhesives, woody or herbaceous plant fibers, small pieces and veneers, and element pieces such as inorganic fibers are bonded to produce woody boards such as plywood, particle board, and fiber board.

  Here, the above-mentioned thermosetting resin adhesive is derived from petroleum, and is further required to be water-based. These adhesives are usually cured by adding formaldehyde. However, since petroleum-derived raw materials are problematic in terms of resources and the environment, it is desirable to reduce the amount used as much as possible. In addition, since formaldehyde is a problem in terms of diffusion, it is preferable that the amount used be small.

  Therefore, conventionally, an adhesive composition containing saccharides and organic sulfonic acid as main components and cured by heating and pressing has been disclosed (for example, see Patent Document 1). As organic sulfonic acids, p-toluenesulfonic acid and benzenesulfonic acid are disclosed.

Japanese Patent Application Laid-Open No. 2014-101489

  Since the adhesive composition containing saccharides and organic sulfonic acid as essential components is solid, it is suitable for being dispersed in powder with respect to the element pieces. However, since organic sulfonic acids such as p-toluenesulfonic acid and benzenesulfonic acid easily absorb moisture, the adhesive composition aggregates under high humidity conditions and is difficult to disperse evenly in the element pieces. .

  The present invention has been made in view of such problems of the prior art. An object of the present invention is to provide a powdery thermosetting adhesive that can be evenly dispersed in the element pieces regardless of humidity conditions, and further has excellent adhesion, and a molded plate using the same. It is in.

  In order to solve the above problems, the powdery thermosetting adhesive according to an embodiment of the present invention contains sugar and camphorsulfonic acid.

  The thermosetting adhesive of the present invention can be bonded under heating and pressure conditions using powdered sugar and powdered camphorsulfonic acid. And since camphorsulfonic acid has low hygroscopicity, it can disperse | distribute uniformly to an element piece irrespective of humidity conditions. In addition, since sugar and camphorsulfonic acid have a high reaction rate, it is possible to shorten the molding time and obtain an adhesive having excellent adhesiveness.

It is a graph which shows the relationship between the amount of water vapor | steam in air | atmosphere at the time of manufacture, and bending strength (MOR) regarding the fiber board of Examples 2-1 and 2-2 and Comparative Examples 2-1 to 2-3. It is a graph which shows the relationship between the amount of water vapor | steam in air | atmosphere at the time of manufacture, and a water absorption thickness expansion coefficient (TS) regarding the fiber board of Examples 2-1 and 2-2 and Comparative Examples 2-1 to 2-3. It is a graph which shows the relationship between the amount of water vapor | steam in air | atmosphere at the time of manufacture, and the amount of formaldehyde emission regarding the fiber board of Examples 2-1 and 2-2 and Comparative Examples 2-1 to 2-3.

  Hereinafter, the thermosetting adhesive according to this embodiment and a molded plate using the thermosetting adhesive will be described in detail.

[Thermosetting adhesive]
(First embodiment)
First, the thermosetting adhesive according to the first embodiment will be described in detail.

  Conventional woody adhesives are generally liquids such as solutions or emulsions. For this reason, an adhesive agent is adhered to an element piece such as a fiber, a small piece, or a veneer of a woody material or a herbaceous plant by a method such as spraying, application, or impregnation, and then adhered. However, several problems arise due to the liquid adhesive.

  Specifically, when an organic solvent is used for the liquid adhesive, the working environment and the recovery of the solvent at the time of board molding become a problem. Further, when water is used for the liquid adhesive, molding is performed while evaporating water at the time of heat molding, so that the temperature is difficult to rise, and molding takes time. And, a phenomenon that water vapor expands and the molded plate is damaged during the manufacturing process, so-called puncture easily occurs. Furthermore, since the adhesive component also moves and aggregates when water evaporates and moves, the adhesive component tends to be unevenly distributed. For this reason, after the dispersion of the liquid adhesive, a pretreatment for removing the solvent is often performed, followed by heat molding. Accordingly, there is a demand for an adhesive that is not a liquid but a solid, such as a powder or fiber, and that can be dispersed in element pieces and solidified by heating.

  The thermosetting adhesive according to this embodiment is an adhesive composition that is cured by heating and pressing. Specifically, the thermosetting adhesive according to this embodiment is in a powder form and further contains sugar and camphorsulfonic acid.

  As the sugar, at least one selected from the group consisting of monosaccharides, disaccharides, oligosaccharides and polysaccharides can be used. Examples of the monosaccharide include glucose, fructose, ribose, arabinose, rhamnose, xylulose, deoxyribose and the like. Examples of the disaccharide include sucrose, maltose, cellobiose, trehalose, and tulanose. Examples of the oligosaccharide include fructooligosaccharide, galactooligosaccharide, mannan oligosaccharide, stachyose and the like. The oligosaccharide may be, for example, a sugar in which 10 or less sugar chains are linked. Examples of the polysaccharide include starch, agarose, alginic acid, glucomannan, inulin, chitin, chitosan, hyaluronic acid, glycogen, and cellulose. As the sugar, one or a combination of the above compounds can be used.

  Moreover, it is preferable that sugar is 1 type, or 2 or more types chosen from monosaccharide and disaccharide. The monosaccharide is preferably at least one of glucose and fructose. The disaccharide is preferably at least one selected from the group consisting of sucrose, maltose and cellobiose. Furthermore, sucrose can be more preferably used as the sugar. In addition, in the thermosetting adhesive of this embodiment, all the above-mentioned sugars are used in a powder form without using a solvent.

  Camphorsulfonic acid (10-camphorsulfonic acid) is a kind of organic sulfonic acid. Other examples of the organic sulfonic acid include p-toluenesulfonic acid, benzenesulfonic acid, methanesulfonic acid, aminoethanesulfonic acid, sulfamic acid and the like. Of such organic sulfonic acids, camphorsulfonic acid is suitable for being dispersed in powder.

Camphorsulfonic acid has a high catalytic effect and can polymerize by proceeding a polymerization reaction between low-molecular modified products of sugar. And the compound obtained by superposing | polymerizing the said low molecular modified substance contributes to adhesion | attachment of element pieces. Furthermore, camphorsulfonic acid has a molecular structure in which a hydrophilic sulfo group (—SO ₃ H) is introduced into a methyl group of a hydrophobic camphor (camphor). Therefore, camphorsulfonic acid has a low water absorption, so that it can be kept in a powder form regardless of humidity conditions. In contrast, p-toluenesulfonic acid, benzenesulfonic acid, and methanesulfonic acid have high catalytic effects and can be polymerized by advancing the reaction between low-molecular modified products of sugar, but have high water absorption. It is difficult to maintain a powder form under high humidity conditions. Therefore, these are not suitable as a powdery adhesive. Aminoethanesulfonic acid and sulfamic acid have a low catalytic effect. Therefore, camphorsulfonic acid is preferably used in this embodiment.

  In the thermosetting adhesive of this embodiment, it is preferable to contain 0.1 to 75 parts by mass of camphorsulfonic acid with respect to 100 parts by mass of sugar. When the sugar is 100 parts by mass, if the content of camphorsulfonic acid is 0.1 parts by mass or more, the effect as a reaction catalyst is easily obtained. Moreover, when the sugar is 100 parts by mass, if the content of camphorsulfonic acid is 75 parts by mass or less, the hydrolysis reaction of the sugar will not be promoted excessively, and the polymerization will be less inhibited. . In addition, it is difficult for the acid to remain, and it is difficult to reduce the strength of the molded body. Further, even when the mixture of the adhesive and the element pieces comes into contact with the press machine or the like during pressurization, metal corrosion is unlikely to proceed.

  More preferably, when the sugar is 100 parts by mass, the content of camphorsulfonic acid is 0.15 parts by mass to 70 parts by mass. More preferably, when the sugar is 100 parts by mass, the content of camphorsulfonic acid is 0.2 parts by mass to 60 parts by mass. Particularly preferably, when the sugar is 100 parts by mass, the content of camphorsulfonic acid is 0.2 parts by mass to 30 parts by mass.

  The sugar is hydrolyzed in the presence of camphor sulfonic acid, temporarily denatured and denatured, and then camphor sulfonic acid serves as a catalyst to accelerate the polymerization reaction between the low molecular weight compounds to be polymerized. For this reason, the polymerized compound contributes to adhesion between the element pieces. Moreover, since camphorsulfonic acid has a lower reactivity with metals than inorganic acids, it is difficult to adversely affect metal facilities and the like during molding. Furthermore, the reaction system of sugar and camphorsulfonic acid does not contain an organic solvent or formaldehyde, nor does it contain a tertiary amine or the like that generates formaldehyde by decomposition. Therefore, it becomes easy to suppress the emission of organic solvents and formaldehyde. This effect can also be caused by the reaction of a saccharide with an acid such as a carboxylic acid. However, the combination of a saccharide and camphorsulfonic acid has a higher reactivity for polymerization. Therefore, the thermosetting adhesive of the present embodiment includes sugar and camphor sulfonic acid as essential components.

  It should be noted that sugar can undergo a reaction of low molecular weight by hydrolysis and subsequent high molecular weight even in the presence of carboxylic acid. However, in the reaction between a saccharide and a carboxylic acid, a reaction containing a fructose residue is fast, but a sugar containing a glucose residue tends to be slow. On the other hand, in the reaction of sugar with camphorsulfonic acid, it was found that the reaction was fast even with a sugar containing no fructose residue.

  Here, the sugar which does not contain a fructose residue is obtained by saccharifying starch produced from corn, potato, sweet potato, tapioca and the like with an enzyme. Specifically, maltose as a disaccharide is obtained by the action of amylase, and glucose (glucose) is obtained by the action of glucoamylase. Cellobiose can be obtained by saccharifying cellulose. These sugars do not contain fructose residues as they are, and the reaction rate is slow in the reaction with carboxylic acids. However, in the reaction between sugar and camphorsulfonic acid, the reaction rate can be increased regardless of the presence or absence of fructose residues. Therefore, the range of sugar selection can be expanded, and a wide variety of sugars can be used, so that an excellent thermosetting adhesive utilizing natural resources can be obtained.

  In the thermosetting adhesive of this embodiment, sugar and camphor sulfonic acid are the main components. Here, the main component is a component that contributes to adhesiveness among the components in the thermosetting adhesive.

  Moreover, the thermosetting adhesive of this embodiment may contain an additive. Examples of the additive include a stabilizer, a colorant, a thickener, a reaction accelerator, and a dispersion aid.

  The thermosetting adhesive of this embodiment is a powder and not a liquid. In other words, when an organic solvent is used, the working environment and solvent recovery in board molding become problems, and when water is used, molding time is likely to occur, and puncture and adhesive components are likely to be unevenly distributed. For this reason, it is preferable that the thermosetting adhesive of this embodiment is not a liquid but a solid, especially a powder that can be easily dispersed.

  And since the above-mentioned component is substantially solid, a powdery thermosetting adhesive can be obtained by mixing. In addition, since the particle size of a powdery thermosetting adhesive is selected by the dispersibility with an element piece, it is not specifically limited.

  The thermosetting adhesive of this embodiment may be composed only of sugar and camphorsulfonic acid. However, the thermosetting adhesive of this embodiment may further contain a petroleum-based thermosetting resin adhesive. That is, the thermosetting adhesive may contain an adhesive mainly composed of a petroleum-derived thermosetting resin. Thereby, the adhesiveness and water resistance of a shaping | molding board can be improved. For wood boards such as particle boards and fiber boards, it is common to use an adhesive mainly composed of amino resin such as phenol resin, urea / melamine resin, or isocyanate resin. Therefore, a petroleum-based thermosetting resin adhesive can be added in the above thermosetting adhesive as long as the physical properties are further improved as long as the adhesiveness is exhibited by sugar and camphorsulfonic acid.

  The petroleum thermosetting resin adhesive is preferably at least one selected from the group consisting of a phenol resin adhesive, a urea / melamine resin adhesive, and an isocyanate resin adhesive, but is not particularly limited. It is preferable to select the type and amount of the petroleum-based thermosetting resin adhesive depending on the use of the molded plate. When strength is required, the amount added can be increased. Moreover, when water resistance is calculated | required, adhesives with high water resistance, such as a phenol resin adhesive and an isocyanate resin adhesive, are suitable. The petroleum thermosetting resin adhesive is preferably powder. In that case, the miscibility with sugar and camphorsulfonic acid can be enhanced.

  When blending a petroleum-based thermosetting resin adhesive, the solid content of the petroleum-based thermosetting resin adhesive is 1 part by mass or more when the total amount of sugar and camphorsulfonic acid is 100 parts by mass. It is preferable to blend so as to be 200 parts by mass or less. In that case, the adhesiveness of the thermosetting adhesive obtained can be improved. However, when a petroleum-based thermosetting resin adhesive is contained, formaldehyde is likely to be generated. Therefore, from the viewpoint of formaldehyde suppression, it is preferable not to contain a petroleum-based thermosetting resin adhesive. Moreover, even if it is a case where a petroleum thermosetting resin adhesive is mix | blended, the one where the quantity is smaller is preferable. Therefore, for example, when the total amount of sugar and camphorsulfonic acid is 100 parts by mass, the solid content of the petroleum-based thermosetting resin adhesive is more preferably 100 parts by mass or less, and 50 parts by mass or less. More preferably, it is more preferably 10 parts by mass or less.

  In the above thermosetting adhesive, even when a petroleum thermosetting resin adhesive is used, the amount of the thermosetting adhesive can be reduced, so that generation of formaldehyde can be suppressed. In addition, petroleum-based thermosetting resin adhesives may cause harmful gas generation during combustion at the time of disposal, but the generation of harmful gas is suppressed by reducing the amount of adhesive used. be able to.

  The thermosetting adhesive of this embodiment is a mixture of the above sugar and camphor sulfonic acid, and optionally a petroleum-based thermosetting resin adhesive, and if necessary, other additives. Can be obtained. At this time, if the powder is mixed, a thermosetting adhesive of powder can be obtained.

  The thermosetting adhesive of the present embodiment can exhibit adhesiveness and adhere to the adherend by heating and pressurizing it between the adherend and the adherend. The heating and pressing are preferably a press. According to the press, the adhesiveness can be easily expressed. The adherend may be two or more solid members having an adhesive surface, or may be a plurality of small pieces formed by a thermosetting adhesive. When bonding two solid members, for example, by placing a thermosetting adhesive between the members by application or spraying, pressing the members in a direction approaching each other, and heating and pressurizing The curing reaction of the thermosetting adhesive proceeds and the members can be bonded. Further, when molding by bonding a plurality of small pieces with a thermosetting adhesive, for example, by mixing a plurality of small pieces with a thermosetting adhesive, placing this mixture in a mold, and heating and pressing, The curing reaction of the thermosetting adhesive proceeds, and a compact can be formed by bonding small pieces.

  The thermosetting adhesive can be used for bonding various members and small pieces. For example, a thermosetting adhesive can be used for metal bonding. Further, the thermosetting adhesive can bond the stainless steel block. Further, the thermosetting adhesive can be used for bonding wood or glass.

(Second embodiment)
Next, the thermosetting adhesive according to the second embodiment will be described in detail. Detailed descriptions of the same materials as those in the first embodiment are omitted.

  The thermosetting adhesive according to the present embodiment further contains a carboxylic acid in addition to the sugar and camphorsulfonic acid detailed in the first embodiment. By containing the carboxylic acid, in addition to the reaction between the sugar and camphorsulfonic acid, the reaction between the sugar and the carboxylic acid can coexist, so that the reactivity can be increased and the adhesion can be improved. . In addition, when the carboxylic acid is contained, the bondability of the obtained cured product is increased, so that the water resistance can be improved.

  The carboxylic acid is preferably contained in an amount of 0.1 to 600 parts by mass with respect to 100 parts by mass of the sugar. When the sugar is 100 parts by mass, the effect of the carboxylic acid is further enhanced when the content of the carboxylic acid is 0.1 parts by mass or more. Further, when the saccharide content is 100 parts by mass, when the carboxylic acid content is 600 parts by mass or less, unreacted carboxylic acid hardly remains and the curability can be improved. More preferably, when the sugar is 100 parts by mass, the carboxylic acid content is 0.2 to 200 parts by mass. More preferably, when the sugar is 100 parts by mass, the content of carboxylic acid is 0.3 parts by mass to 100 parts by mass. Note that the content of carboxylic acid may be less than the content of camphorsulfonic acid. For example, the content of carboxylic acid may be less than half of the content of camphorsulfonic acid.

  As the carboxylic acid, at least one of a monovalent carboxylic acid and a polyvalent carboxylic acid can be used. The polyvalent carboxylic acid is preferably an organic carboxylic acid having a plurality of carboxyl groups (COOH) in one molecule. In addition, it is more preferable that the thermosetting adhesive of this embodiment further contains a polyvalent carboxylic acid and 0.1 to 600 parts by mass of the polyvalent carboxylic acid with respect to 100 parts by mass of the sugar. By using a polyvalent carboxylic acid as the carboxylic acid, it is possible to further promote the reaction of reducing the molecular weight of sugar by hydrolysis and the subsequent polymerization in the presence of camphorsulfonic acid.

  Examples of the monovalent carboxylic acid include formic acid, acetic acid, propionic acid, butyric acid, valeric acid, lactic acid, benzoic acid and the like. As the polyvalent carboxylic acid, at least one selected from the group consisting of a divalent carboxylic acid, a trivalent carboxylic acid, a tetravalent carboxylic acid, and a pentavalent or higher carboxylic acid can be used. Of these, divalent to tetravalent carboxylic acids are preferable because they are easy to use. Examples of the polyvalent carboxylic acid include citric acid, itaconic acid, malic acid, tartaric acid, succinic acid, oxalic acid, adipic acid, malonic acid, phthalic acid, sebacic acid, maleic acid, fumaric acid, glutaric acid (pentanedioic acid). ), Gluconic acid, glutaconic acid, pentenedioic acid and the like. These monovalent carboxylic acids and polyvalent carboxylic acids may be anhydrides. Among these, the polyvalent carboxylic acid preferably contains at least one of citric acid and itaconic acid. Citric acid and itaconic acid can be produced from plants. In this case, since the use of fossil resources can be suppressed, the load on the environment is reduced, which is preferable.

  The polyvalent carboxylic acid may have a hydroxyl group. In that case, it becomes possible to improve adhesiveness. The polyvalent carboxylic acid preferably has a molecular weight of 500 or less, more preferably 300 or less. When the molecular weight of the polyvalent carboxylic acid is small, the catalytic efficiency for sugar can be increased.

  The thermosetting adhesive of this embodiment contains sugar, camphorsulfonic acid and carboxylic acid, but preferably does not contain excessive polyvalent carboxylic acid. As mentioned above, polyvalent carboxylic acids may react slowly with sugars. Moreover, when polyhydric carboxylic acid is contained excessively, progress of reaction with saccharide | sugar and camphorsulfonic acid may be prevented. Therefore, it is preferable that the thermosetting adhesive of this embodiment contains a polyvalent carboxylic acid within the above range.

  When the thermosetting adhesive contains a carboxylic acid, the reaction between the sugar and the carboxylic acid is slower than the reaction between the sugar and camphorsulfonic acid, so the carboxylic acid can remain as an unreacted material left behind in the reaction. There is sex. If carboxylic acid remains after curing, the curing reaction may not proceed sufficiently. Therefore, it is preferable that no carboxylic acid remains after curing. In order to prevent carboxylic acid from remaining after curing, the thermosetting adhesive only needs to contain carboxylic acid to such an extent that carboxylic acid does not remain after curing. In particular, polyvalent carboxylic acids are expected to react with sugars, but if they remain, the adhesiveness may not be sufficiently exhibited. Therefore, it is preferable that no polycarboxylic acid remains after curing.

  Unreacted carboxylic acid after curing can be confirmed by analyzing the cured product obtained by curing the thermosetting adhesive. For example, whether a carboxylic acid is contained is detected by analyzing a hot water extract of the cured product by nuclear magnetic resonance (1H NMR) or by high performance liquid chromatography (HPLC). be able to. At this time, polyvalent carboxylic acid can also be detected. Although there are differences depending on the accuracy of the device, the number of integrations, the amount of extraction, the presence or absence of concentration, etc., the lower limit of detection is about 100 ppm as the concentration in the hot water extraction solution. Therefore, carboxylic acid can be detected if the concentration is 100 ppm or more. From this, when 1 g of the cured product is extracted with 10 mL of hot water, it is possible to detect up to about 1 mg, that is, a content of about 0.1% by mass of the cured product. Whether the carboxylic acid is positively added to the thermosetting adhesive can be determined based on the concentration of the remaining carboxylic acid.

  In the thermosetting adhesive of this embodiment, sugar and camphor sulfonic acid are the main components for adhesion, and carboxylic acid is a component that assists adhesion. Therefore, the thermosetting adhesive of this embodiment may be composed only of sugar, camphorsulfonic acid and carboxylic acid. However, as in the first embodiment, the thermosetting adhesive of this embodiment may contain a petroleum-based thermosetting resin adhesive. That is, the thermosetting adhesive may contain an adhesive mainly composed of a petroleum-derived thermosetting resin. Thereby, the adhesiveness and water resistance of a shaping | molding board can be improved. For wood boards such as particle boards and fiber boards, it is common to use an adhesive mainly composed of amino resin such as phenol resin, urea / melamine resin, or isocyanate resin. Therefore, in the above thermosetting adhesive, as long as the adhesiveness is exhibited by sugar, camphorsulfonic acid and carboxylic acid, a petroleum thermosetting resin adhesive may be added for further improvement of physical properties. it can.

  The thermosetting adhesive of this embodiment is a mixture of sugar, camphorsulfonic acid and carboxylic acid, and optionally a petroleum thermosetting resin adhesive, and if necessary, other additives. Can be obtained. As other additives, those described in the first embodiment can be used. A powder thermosetting adhesive can be obtained by mixing these raw materials in powder form.

  Note that the thermosetting adhesive of the present embodiment also exhibits adhesiveness by being heated and pressed between the adherend and the adherend, as in the first embodiment. The material can be glued. The thermosetting adhesive can also be used for bonding various members and small pieces.

[Molded plate]
Next, the molded plate according to the present embodiment will be described in detail. The molding board of this embodiment contains the above-mentioned thermosetting adhesive and the some plant piece adhere | attached with a thermosetting adhesive.

  As described above, a molded body can be formed by using the thermosetting adhesive of the present embodiment and a plurality of small pieces. Since a small piece becomes an element in a molded object, you may call it an element piece. And since the thermosetting adhesive of this embodiment exhibits adhesiveness by heating and pressurization, it can be used suitably for formation of a molded object. In addition, the thermosetting adhesive may not contain an organic solvent or formaldehyde in the reaction system, and may not contain a tertiary amine that generates formaldehyde by decomposition. Therefore, it is possible to suppress the diffusion of the organic solvent derived from the adhesive and the diffusion of formaldehyde.

  The molded body of the present embodiment is preferably a molded plate. Formed boards (boards) are preferable because they can be applied to various materials including architecture and have a wide range of applications. And as a preferable example of a shaping | molding board, a glass fiber containing shaping | molding board is mentioned. Glass fiber can be applied to various materials, and if the above thermosetting adhesive is used, a good glass fiber-containing molded plate can be obtained. Moreover, an airgel containing molded board is mentioned as another preferable example of a molded board. Since airgel has high porosity, it is lightweight and has high heat insulating properties, it can be applied to heat insulating materials and heat insulating boards.

  Further, by using a thermosetting adhesive, an inorganic small piece molded plate can be formed. In this case, an inorganic board can be obtained. For example, a rock wool board can be obtained from rock wool and a thermosetting adhesive. For example, a glass wool board can be obtained from glass wool and a thermosetting adhesive. When the above-mentioned thermosetting adhesive is used as an adhesive that hardens the inorganic pieces, the thermosetting adhesive forms a polymer cured product, so that excellent adhesiveness and moldability can be exhibited.

  The thermosetting adhesive of this embodiment is preferably used for bonding plant pieces. Thereby, the molded object which a plant piece adhere | attaches with a thermosetting adhesive agent can be obtained. The molded body may be a molded plate. Therefore, a shaping | molding board is obtained as a thing to which the plant piece was adhere | attached with said thermosetting adhesive.

  Examples of plants used as raw materials for plant fragments include woody plants such as conifers and broad-leaved trees, annual or biennial herbaceous plants, or agricultural waste after harvesting grains, vegetable oils, plant sugars, and the like. Specific examples of agricultural waste include herbs such as kenaf, rice, bamboo, and flax, bagasse, beet pulp, rice straw, wheat straw, and oil palm fiber. By using these, effective use of resources can be achieved. In particular, the utilization of resources can be promoted by using annual or biennial herbaceous plants or agricultural waste.

  Here, woody plants such as conifers and hardwoods contain a large amount of cellulose, hemicellulose, and lignin. In addition, herbaceous plants have cellulose, hemicellulose, and lignin as main constituents, the same as woody plants. Furthermore, herbaceous plants have a high content of low-molecular components such as hemicellulose components and hot water-soluble components compared to woody plants, and are characterized by being rich in components that denature into adhesive components under heat and pressure. . Therefore, it is suitable for the material of the forming plate.

  Specific examples of the hemicellulose component include arabinoglucuronoxylan, glucomannan, and glucuronoxylan. Arabinoglucuronoxylan and glucomannan are components that are mainly contained in conifers. Glucuronoxylan and glucomannan are components that are mainly contained in hardwoods. The plant piece may contain these components or components similar thereto.

  The plant piece may be obtained by cutting a plant, etc., and may be a small piece, a fiber, a single plate, or a powder. Good. A plant piece is contained in a shaping | molding board, and becomes an element piece which comprises the one part. The molded board obtained by the plant piece and the thermosetting adhesive can be a wooden molded board or a wooden board. Here, the wooden molded plate is a molded product having a wood-like texture, and even those obtained from plants other than wood are included in the wooden molded plate and the wooden board.

  The plant piece preferably contains at least one selected from the group consisting of a cellulose component, a hemicellulose component and lignin. In that case, since adhesiveness can be expressed by the component derived from a plant piece, adhesiveness can be improved. Moreover, the plant piece may contain sugar. In that case, since the sugar derived from a plant piece reacts with camphorsulfonic acid to develop adhesiveness, the adhesive force between the plant piece and the thermosetting adhesive can be further increased.

  As the plant piece, a wood piece obtained by cutting wood can be used. Examples of the wood pieces include a saw board, a single board, a wood strand, a wood chip, and a wood fiber. A material obtained by bonding wood pieces with an adhesive can be a wood board such as a laminated board, plywood, particle board, fiber board, or MDF. Moreover, when said thermosetting adhesive is used as an adhesive agent, since the thermosetting adhesive forms a polymer cured product, excellent adhesiveness and moldability can be expressed. Although it does not specifically limit as wood, Appropriate materials, such as a cedar, a cypress, a hiba, a pine, a hemlock, and a drill, may be sufficient.

  A herbaceous plant can also be used as the plant piece. As the herbaceous plant, at least one of sugar cane and sugar beet can be used. Since these can utilize residual sugar, physical properties are improved when the above-mentioned thermosetting adhesive is used. In addition, since the remaining sugar can be reduced in the molded plate, the physical properties can be improved. In particular, bagasse, which is a pomace of sugarcane, can be used effectively.

  Low molecular components such as hemicellulose components, sugars, and hot water soluble components contained in plant fragments are denatured into adhesive components under heat and pressure, but the reaction is promoted by the coexistence of camphorsulfonic acid, resulting in a strong adhesive component. . That is, hemicellulose components and sugars are hydrolyzed by the presence of camphorsulfonic acid to temporarily lower the molecular weight, and then camphorsulfonic acid serves as a catalyst to promote the polymerization reaction between the low molecular compounds. Therefore, when these components are contained in the plant piece, the adhesiveness is further increased.

  Further, when the thermosetting adhesive contains an organic carboxylic acid, the organic carboxylic acid contributes to the modification of the hemicellulose component and sugar. Furthermore, organic carboxylic acid ester-bonds with the hydroxyl group in the cellulose, hemicellulose, lignin, and a hot water soluble component contained in a plant piece, and reduces the hydroxyl group which worsens water absorption and hygroscopicity. For this reason, the water resistance, hot water resistance, and moisture resistance of the molded plate are improved. In addition, if low molecular components such as hemicellulose and sugar remain in the molding plate, this component may cause mold generation. However, the addition of organic carboxylic acid may cause low molecular components such as hemicellulose and sugar in the molding plate. The residual amount can be reduced. Therefore, it is possible to obtain a molded plate in which generation of mold is suppressed.

  Thus, when camphor sulfonic acid is allowed to coexist with plant pieces, the molded plate can be molded in a short time. On the other hand, if camphorsulfonic acid is not present, the reaction between the modified low molecular weight compounds is slowed, which may lead to a decrease in physical properties. Moreover, since camphorsulfonic acid has lower reactivity with metals than inorganic acids, it hardly causes adverse effects on metal facilities and the like during molding. Further, the reaction system of sugar and camphorsulfonic acid does not contain an organic solvent or formaldehyde, and does not contain a tertiary amine or the like that generates formaldehyde by decomposition. Therefore, it becomes easy to suppress the emission of the organic solvent and formaldehyde derived from the molded product.

  The plant pieces may have a ratio of soluble components obtained by extraction with hot water of 90 ° C. for 3 hours to 3% by mass or more in the dry components. Thereby, excellent adhesiveness can be obtained. That is, since the hot water-soluble component may contain a substance that can be modified into an adhesive component, the adhesiveness can be further improved. In addition, a dry component means the component when it becomes constant weight when a plant piece is heated at 105 degreeC, ie, the component when it becomes constant weight.

  Although the upper limit of the said soluble component ratio is not specifically limited, Preferably it is 10 mass% or less. When it exceeds 10 mass%, there exists a possibility of causing the fall of the physical property as a plant piece. In addition, if the amount of reactive substances in the hot water-soluble component increases too much, it takes time for all the hot water-soluble components to react, and the components such as cellulose are relatively reduced. There is a risk that physical properties will deteriorate. The soluble component ratio of the plant piece is more preferably 5% by mass or more and 10% by mass or less in the dry component.

  Specific examples of the hot water-soluble component in the plant piece include low-molecular sugars such as monosaccharides and oligosaccharides, polysaccharides such as pectin, tannins and lignans. And in plant pieces, low-molecular sugars such as monosaccharides and oligosaccharides which are hot water-soluble components, polysaccharides such as pectin, tannins, lignans and the like contribute to adhesion. These hot water soluble components contribute to adhesion because camphor sulfonic acid serves as a catalyst and polymerizes by advancing the reaction between the modified products and the reaction between the modified product and the carboxylic acid.

  The plant which is the raw material of the molded plate can be processed into particles having a diameter of several hundreds μm to several cm by pulverization. Moreover, the plant used as the raw material of the molded plate has a diameter (fiber diameter) of about 50 μm to 2 mm and a length (fiber length) of about 100 μm to 20 mm by defibrating the bast portion and stem core portion. It can be processed into fine fibers. Then, using these particles and fine fibers as plant pieces (fine pieces), a molded plate can be produced.

  When using the plant piece containing sugar, 3 mass% or more of the content rate of the sugar obtained by extracting the said plant piece with 90 degreeC hot water for 3 hours may be sufficient. Thereby, since the sugar in a plant piece can be utilized for adhesion | attachment, adhesiveness can be improved. Although the upper limit of the content rate of the sugar in a plant piece is not specifically limited, Preferably it is 10 mass% or less.

  In addition, when using the plant piece containing sugar, the sugar in a plant piece contributes to adhesiveness. That is, the sugar in the plant piece reacts with camphorsulfonic acid. Therefore, in the thermosetting adhesive, camphorsulfonic acid can sufficiently exhibit adhesiveness even when the amount is more than 75 parts by mass with respect to 100 parts by mass of the sugar in the thermosetting adhesive. For example, camphorsulfonic acid may be 100 parts by mass or more or 200 parts by mass or more with respect to 100 parts by mass of the sugar in the thermosetting adhesive. The upper limit of the content of camphor sulfonic acid in this case is not particularly limited, but camphor sulfonic acid is preferably 10000 parts by mass or less with respect to 100 parts by mass of sugar in the thermosetting adhesive, and 1000 parts by mass. It is more preferable that

  When bonding plant pieces, the thermosetting adhesive preferably further contains carboxylic acid in addition to sugar and camphorsulfonic acid as in the second embodiment described above. When the carboxylic acid is used, the carboxylic acid can complement the catalytic reaction of camphorsulfonic acid to exert a catalytic action, and the adhesiveness can be improved. Moreover, when the reaction of camphorsulfonic acid and the reaction of carboxylic acid are mixed, a stronger cured product can be formed, and a molded plate having high strength can be obtained.

  The molded plate can be produced by mixing a small piece, which is an adherend, and the above-mentioned thermosetting adhesive, and molding the mixture by heating and pressing. When a plant piece is used as the adherend, the plant piece used as a raw material may be a dry raw material. Thereby, handling becomes easy. Moreover, the ground material which grind | pulverized the shaping | molding board using a plant piece can also be used as a plant piece. In that case, the plant piece can be reused. In molding, heat and pressure molding can be efficiently performed by using sugar and camphorsulfonic acid in combination. For this reason, it becomes possible to perform heat-press molding in a shorter time.

  The method for attaching the thermosetting adhesive to the above-mentioned plant piece is not particularly limited. For example, the plant piece and the powdered thermosetting adhesive may be mixed in a dry manner. At this time, for example, it is preferable that the liquid is attached to the plant piece, and the plant piece to which the liquid is further attached and the powder thermosetting adhesive are mixed. By adhering the liquid to the plant piece, the powder thermosetting adhesive is easily fixed on the surface of the plant piece, so that the thermosetting adhesive can be more highly dispersed. As the liquid, water or an organic solvent can be used, but water is more advantageous from the viewpoint of productivity.

  And a thermosetting adhesive reacts and it can obtain a shaping | molding board by heating the mixture of a plant piece and a powder thermosetting adhesive, pressurizing. Moreover, when using a plant piece, the adhesion component which arises when the component contained in the plant piece itself denatures is added, and a plant piece is adhere | attached.

  The conditions for heat and pressure molding, for example, the molding pressure, molding temperature, molding time, and the like can be appropriately set depending on the type and shape of the plant piece, its surface condition, the thickness of the molding plate, and the like. The molding temperature is preferably 140 ° C. or higher and 220 ° C. or lower. When the molding temperature is 220 ° C. or lower, the deterioration of the components hardly proceeds, so that the physical properties as a molded plate are difficult to decrease. On the other hand, when the molding temperature is 140 ° C. or higher, the reaction rate is unlikely to decrease and the composition is easily cured. The molding temperature is more preferably 200 ° C. or lower. In this case, deterioration of the adherend can be suppressed. The molding temperature is preferably 160 ° C. or higher. In this case, the reaction rate is less likely to decrease, and the curing becomes easier.

  The molding pressure is appropriately set depending on the thickness and specific gravity of the molded plate, but is preferably 0.5 MPa or more and 4 MPa or less. When the molding pressure is 0.5 MPa or more, it is possible to sufficiently press-bond, and it is easy to improve the strength of the molded plate. When the molding pressure is 4 MPa or less, the molding pressure is not too large and the molded plate is hardly broken. The molding pressure is more preferably 3 MPa or less. In this case, it is possible to make the board more difficult to break. The molding pressure is more preferably 0.7 MPa or more. In this case, the thermosetting adhesive and the adherend can be sufficiently bonded, and the strength of the molded plate can be further increased.

  Regarding the molding time, for example, it can be in the range of 1 minute to 60 minutes, preferably 2 minutes to 30 minutes, more preferably 3 minutes to 15 minutes. Thereby, a favorable molded board can be manufactured efficiently.

  The mixing ratio of the plant piece and the thermosetting adhesive is appropriately set depending on the raw materials to be used, molding conditions, properties of the molded plate, etc., and is not particularly limited. However, in this embodiment, it is preferable to contain 5-30 mass parts of thermosetting adhesives with respect to 100 mass parts of dry mass of a plant piece. If the amount of the thermosetting adhesive is too small, the adhesive strength may be reduced, and if the amount of the thermosetting adhesive is too large, an adhesive layer may be formed and the interfacial adhesion may be reduced. The thermosetting adhesive is preferably blended at the above ratio. As for a thermosetting adhesive agent, it is more preferable that it is 8 mass parts or more with respect to 100 mass parts of dry mass of a plant piece. In this case, the adhesiveness is further increased. Moreover, as for a thermosetting adhesive agent, it is more preferable that it is 25 mass parts or less with respect to 100 mass parts of dry mass of a plant piece. In this case, a decrease in interfacial adhesion can be further suppressed. In addition, the dry mass of a plant piece means the mass when a plant piece becomes constant weight when heated at 105 ° C., that is, a constant weight.

  The molded plate of this embodiment may further contain a powdery petroleum-based thermosetting resin adhesive. By containing a petroleum-based thermosetting resin adhesive, it becomes possible to further improve the adhesion and water resistance of the molded plate.

  As a method of attaching a petroleum-based thermosetting resin adhesive to a plant piece, as in the above-described thermosetting adhesive, a powdery petroleum-based thermosetting resin adhesive is directly sprayed on the plant piece. be able to. In addition, when the petroleum-based thermosetting resin adhesive is dissolved in water, it can be attached by a method suitable for a liquid, such as spraying, coating, or impregnation, separately from the thermosetting adhesive.

  In addition, it is preferable that sugar is not left as much as possible on the obtained molded plate. Thereby, while improving adhesiveness, water resistance can be improved. In addition, when no sugar remains, the generation of mold can be suppressed. That is, the sugar in the thermosetting adhesive is modified with camphorsulfonic acid, but it is preferable that the total amount of the sugar is modified. Moreover, when a plant piece contains saccharide | sugar, it is preferable to also modify | denature the saccharide | sugar in a plant piece. For example, the ratio of the sugar obtained by extracting the molded plate with hot water at 90 ° C. for 3 hours is preferably less than 5% by mass, and more preferably 1% by mass or less. Moreover, it is more preferable that the ratio of the said saccharide | sugar is 0.5 mass% or less in a dry component, and it is especially preferable that it is 0.1 mass% or less. In addition, a dry component means the component when it becomes constant weight when a shaping | molding board is heated at 105 degreeC, ie, a component when it becomes constant weight.

  It is better that the resulting molded plate contains as little carboxylic acid derived from the thermosetting adhesive as possible. That is, the carboxylic acid in the thermosetting adhesive is used for the reaction with the sugar, but it is preferable that the entire amount of the carboxylic acid is used for the reaction and does not remain. Thereby, while improving adhesiveness, water resistance can be improved. For example, the ratio of the carboxylic acid obtained by extracting the molded plate with hot water at 90 ° C. for 3 hours is preferably less than 5% by mass, more preferably 1% by mass or less. . Further, the ratio of the carboxylic acid is more preferably 0.5% by mass or less, and particularly preferably 0.1% by mass or less in the dry component.

  The molded plate may be provided with a surface material on one surface or both surfaces thereof. By providing the surface material, the strength of the molded plate can be increased. The surface material may be a board shape, a sheet shape, or the like. In this case, the molded plate becomes a part of the composite molded plate made of the composite material. The surface material may be provided by being adhered to the molded plate after molding, or may be provided by being overlapped at the time of molding the molded plate and adhered by a component in the thermosetting adhesive. As the surface material, a board-like material such as wood, particle board or fiberboard, a veneer formed by thinly slicing wood, a decorative sheet made of plastic or paper, a sheet-like material such as a moisture-proof sheet, etc., as appropriate Can be used.

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

[Examples 1-1 and 1-2, and Comparative Examples 1-1 to 1-3]
(Sample preparation)
First, sucrose (manufactured by Wako Pure Chemical Industries, Ltd., the same applies below) and citric acid (manufactured by Wako Pure Chemical Industries, Ltd., the same applies below) are weighed and mixed while being ground in a mortar at the ratio shown in Table 1. Sucrose-citric acid powder was prepared.

  The obtained sucrose-citric acid powder was transferred to a Teflon (registered trademark) processed container, and then an organic sulfonic acid powder was added and mixed with a spoon. Then, the Teflon container containing the mixture was placed on a 200 ° C. hot plate, covered with a 500 mL beaker, and heated for 30 minutes to obtain a cured sample of each example. As organic sulfonic acid, camphorsulfonic acid was used in Examples 1 and 2. Further, p-toluenesulfonic acid was used in Comparative Example 1, aminoethanesulfonic acid was used in Comparative Example 2, and sulfamic acid was used in Comparative Example 3.

(Hot water extraction)
A sample of each cured example and 15 mL of distilled water were added to a 50 mL eggplant flask and subjected to hot water extraction. In addition, hot water extraction was performed by heating the mixture of a sample and distilled water at 90 degreeC for 3 hours. And the mixture after hot water extraction was filtered, and it isolate | separated into the hot water insoluble material and the hot water soluble material.

(Drying and mass measurement)
The hot water insoluble material and the hot water soluble material were dried with a dryer at 105 ° C., and then mass measurement was performed. And the ratio of the hot water soluble material was calculated from the mass of the sample before hot water extraction and the mass of the hot water soluble material. The ratio of the hot water soluble material is shown in Table 1.

  As shown in Table 1, in Example 1-1 and Example 1-2 using camphor sulfonic acid, the ratio of the hot water soluble material after the reaction was compared with Comparative Examples 1-2 and 1-3. It was found to be low and highly reactive with sugar. Moreover, from Examples 1-1 and 1-2 and Comparative Example 1-1, it was found that camphorsulfonic acid had a high catalytic effect equivalent to p-toluenesulfonic acid.

[Examples 2-1 and 2-2, and Comparative Examples 2-1 to 2-4]
(Sample preparation)
(Example 2-1)
As a plant fiber, a bute fiber bundle of jute (width: 1 to 2 cm, length: 2 to 4 m) was cut in the length direction by a cutting machine, and then mechanically defibrated using a lapping machine. As a result, jute plant fibers having an average fiber length of about 55 mm and an average fiber diameter of about 150 μm were obtained.

Then, air in the amount of steam ^{3.0g / m 3, 7.6g / m} 3, in a different day 16.6 g / ^{m 3,} respectively mixed powder adhesive and vegetable fibers, after forming the mat, A fiber board was produced by heating and pressing with a hot press.

  Specifically, after mixing the components of the powder adhesive in advance, the plant fiber and the powder adhesive are put into a small cotton blender with a pinned cylinder and mixed so that the fibers and the powder adhesive are uniform. To make a mixture. In addition, each component of the powder adhesive used the following, and the compounding ratio of the powder adhesive and the vegetable fiber was adjusted as follows.

・ Powder adhesive: sucrose (Wako Pure Chemical Industries, Ltd.) (average particle size of about 20 μm), 5 parts by mass ・ Powder adhesive: citric acid (Wako Pure Chemical Industries, Ltd.) (average particle size of about 20 μm), 2 parts by mass / powder adhesive: camphorsulfonic acid (manufactured by Wako Pure Chemical Industries, Ltd.) (average particle size of about 20 μm), 1 part by mass / powder adhesive: powdered phenol resin adhesive (manufactured by Gunei Chemical Industry Co., Ltd.) (Average particle diameter of about 20 μm), 8 parts by mass / vegetable fiber: jute bast fiber, 84 parts by mass

  Next, this mixture was sprinkled on the mold using a simple forming device (inner size in mold: 30 cm square) to form a mat, thereby obtaining a fiber mat. Here, the spraying amount of the mixture was adjusted so that the mass of the obtained fiber mat was about 290 g.

This fiber mat is heated and pressed under the conditions of a temperature of 200 ° C., a pressure of 2 MPa, and a time of 5 minutes using a small hot press machine, thereby producing a fiber of this example having a 30 cm square size and a thickness of 4.5 mm. Got the board. The density of this fiber board was about 750 kg / m ³ .

(Example 2-2)
A fiber board of this example was produced in the same manner as in Example 1 except that the powder adhesive was changed to the following materials and blends.
・ Powder adhesive: sucrose, 10 parts by mass ・ Powder adhesive: citric acid, 4 parts by mass ・ Powder adhesive: camphorsulfonic acid, 2 parts by mass

(Comparative Example 2-1)
A fiber board of this example was produced in the same manner as in Example 1 except that the powder adhesive was changed to the following materials and blends.
-Powder adhesive: sucrose, 5 parts by weight-Powder adhesive: citric acid, 2 parts by weight-Powder adhesive: p-toluenesulfonic acid, 1 part by weight-Powder adhesive: Powdered phenol resin adhesive, 8 parts by weight

(Comparative Example 2-2)
A fiber board of this example was produced in the same manner as in Example 1 except that the powder adhesive was changed to the following materials and blends.
-Powder adhesive: sucrose, 10 parts by mass-Powder adhesive: citric acid, 4 parts by mass-Powder adhesive: p-toluenesulfonic acid, 2 parts by mass

(Comparative Example 2-3)
A fiber board of this example was produced in the same manner as in Example 1 except that the powder adhesive was changed to the following materials and blends.
・ Powder adhesive: Powdered phenol resin adhesive, 16 parts by mass

(Comparative Example 2-4)
An attempt was made to produce the fiber board of this example in the same manner as in Example 1 except that the powder adhesive was changed to the following materials and blends, but could not be formed into a board shape.
・ Powder adhesive: 11 parts by mass of sucrose ・ Powder adhesive: citric acid, 5 parts by mass

(Evaluation)
About the fiber board produced by said Example 2-1 and 2-2 and comparative example 2-1 to 2-4, according to the prescription | regulation of JISA5905 (fiber board), bending strength (MOR), water absorption thickness The expansion coefficient (TS) and formaldehyde emission were measured. The results of bending strength are shown in Table 2 and FIG. 1, the results of water absorption thickness expansion rate are shown in Tables 3 and 2, and the results of formaldehyde emission are shown in Tables 4 and 3.

  As shown in Tables 2 to 4, Comparative Example 2-4 did not adhere sufficiently under the current molding conditions, and a fiber board capable of measuring physical properties could not be produced. This is thought to be because the curing reaction of the adhesive was delayed because no organic sulfonic acid was added. On the other hand, Examples 2-1 and 2-2, and Comparative Examples 2-1 to 2-3 were able to produce a fiber board regardless of the amount of water vapor.

  Moreover, as a result of visually observing the mixing process of the jute plant fiber and the powder adhesive, even when Examples 2-1 and 2-2 were produced under conditions with a large amount of water vapor, the dispersion of the adhesive was uniform. It was. Furthermore, in Examples 2-1 and 2-2, the physical properties (bending strength and water absorption thickness expansion coefficient) of the fiber board were also good regardless of the amount of water vapor.

  However, regarding Comparative Examples 2-1 and 2-2, the mixing process was visually observed. As a result, when the amount of water vapor was large, the dispersion of the adhesive became uneven. In Comparative Examples 2-1 and 2-2, when the amount of water vapor is large, the physical properties (bending strength and water absorption thickness expansion coefficient) of the fiber board are deteriorated. This is because, in Comparative Examples 2-1 and 2-2, p-toluenesulfonic acid having high hygroscopicity was used, so that the adhesives aggregated together, and the dispersibility of the adhesive to the fibers decreased. It is also thought that it has declined.

  Since Comparative Example 2-3 used only the phenol resin adhesive as the petroleum-based thermosetting resin adhesive as the adhesive, the physical properties of the fiber board were high regardless of the amount of water vapor. However, since hexamethylenetetramine as a curing agent was added to the powdered phenol resin adhesive, the amount of formaldehyde emitted increased due to the decomposition of this component. On the other hand, in Examples 2-1 and 2-2, it can be seen that the formaldehyde emission amount is reduced regardless of the water vapor amount.

[Reference Examples 1 and 2]
(Sample preparation)
(Reference Example 1)
As a plant material, the kenaf stem core part after removing the bast fiber which becomes the outer skin part of the kenaf stem which is herbaceous was used. And the chip | tip of the kenaf stalk core part was obtained by cut | disconnecting a kenaf stalk core part to about 5 cm in length, and grind | pulverizing this using a grinder (ring flaker). The dimensions of this chip were an average length of 15 mm, an average width of 5 mm, and an average thickness of 2 mm. In addition, the ratio of the soluble component obtained by extracting a kenaf stalk core chip | tip with 90 degreeC hot water for 3 hours was 5.8 mass% in a dry component.

  Next, a liquid adhesive was prepared using sucrose as the sugar and p-toluenesulfonic acid as the organic sulfonic acid. Specifically, a liquid adhesive was prepared by mixing sucrose, p-toluenesulfonic acid and water in a mass ratio of sucrose: p-toluenesulfonic acid: water = 10: 5: 15.

And said liquid adhesive was sprayed with the spray so that solid content addition rate might be 15 mass parts with respect to 100 mass parts of said kenaf stalk core chips. Thereafter, kenaf stalk core chips were laminated to form a laminated mat, and this laminated mat was compressed at a surface pressure of 2 MPa for 10 minutes while being heated to 200 ° C. with a heating press. As a result, a kenaf stalk core chip board of this example having a thickness of 5 mm and an air-drying density of 0.6 g / cm ³ was obtained.

(Reference Example 2)
First, a liquid adhesive was prepared using sucrose as a sugar, p-toluenesulfonic acid as an organic sulfonic acid, and citric acid as a polyvalent carboxylic acid. Specifically, sucrose, p-toluenesulfonic acid, citric acid and water are mixed at a mass ratio of sucrose: p-toluenesulfonic acid: citric acid: water = 4.7: 0.3: 15: 20. By doing so, a liquid adhesive was prepared.

Next, with respect to 100 parts by mass of the kenaf stalk core chip used in Reference Example 1, the liquid adhesive was sprayed so that the solid content addition rate was 20 parts by mass. Thereafter, kenaf stalk core chips were laminated to form a laminated mat, and this laminated mat was compressed at a surface pressure of 2 MPa for 10 minutes while being heated to 200 ° C. with a heating press. As a result, a kenaf stalk core chip board of this example having a thickness of 5 mm and an air-drying density of 0.6 g / cm ³ was obtained.

(Evaluation)
For the kenaf stalk core chip board produced in Reference Examples 1 and 2, peel strength and water absorption thickness expansion coefficient (TS) were measured in accordance with the provisions of JIS A5905 (fiberboard). The water absorption thickness expansion rate test includes a room temperature water expansion rate test in which a 50 mm square kenaf stalk core chipboard is immersed in water at 20 ± 1 ° C. for 24 hours, and a 200 mm square kenaf stalk core chipboard at 80 ± 1 ° C. Two types of hot water expansion coefficient tests were performed, which were immersed in hot water for 5 minutes. Table 5 shows the measurement results of the peel strength and the water absorption thickness expansion coefficient.

  As shown in Table 5, when the reference example 1 using sucrose and p-toluenesulfonic acid was compared with the reference example 2 using sucrose, p-toluenesulfonic acid and citric acid, the peel strength and the water absorption thickness were compared. It can be seen that the coefficients of expansion are equivalent. That is, it can be seen that the same adhesive strength can be obtained without using carboxylic acid (citric acid) as the adhesive. And from Example 1-1 and Comparative Example 1-1, camphorsulfonic acid has a catalytic effect equivalent to p-toluenesulfonic acid. From these, it can be seen that even when the powdery thermosetting adhesive does not contain carboxylic acid and is composed of sugar and camphorsulfonic acid, it is excellent in adhesiveness.

  As described above, the contents of the present embodiment have been described according to the examples. However, the present embodiment is not limited to these descriptions, and it is obvious to those skilled in the art that various modifications and improvements are possible. is there.

Claims (7)

Sugar,
Camphorsulfonic acid,
A powdery thermosetting adhesive containing   The thermosetting adhesive according to claim 1, wherein the sugar is one or more selected from monosaccharides and disaccharides.   The thermosetting adhesive according to claim 1 or 2, comprising 0.1 to 75 parts by mass of the camphorsulfonic acid with respect to 100 parts by mass of the sugar. Further containing a polyvalent carboxylic acid,
The thermosetting adhesive according to any one of claims 1 to 3, comprising 0.1 to 600 parts by mass of the polyvalent carboxylic acid with respect to 100 parts by mass of the sugar. The thermosetting adhesive according to any one of claims 1 to 4,
A plurality of plant pieces adhered by the thermosetting adhesive;
Molded plate containing   The molded board of Claim 5 which contains 5-30 mass parts of said thermosetting adhesives with respect to 100 mass parts of dry mass of the said plant piece.   The molded board according to claim 5 or 6, further comprising a powdery petroleum-based thermosetting resin adhesive.

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