JP2006205695A - Adhesive composition for wooden fibrous plate and manufacturing method of wooden fibrous plate using composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an adhesive composition capable of giving a wooden fibrous plate having excellence in both performance of high stiffness and high tenacity, and to provide a manufacturing method of the wooden fibrous plate using the composition. <P>SOLUTION: The object is achieved by using the adhesive composition for the the wooden fibrous plate, and the composition comprises a compound having two or more isocyanate groups in a molecule, wax emulsion and a compound having three or more hydroxyl groups in a molecule. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an adhesive composition for a wood fiber board, and a method for producing a wood fiber board using the composition. Specifically, it is possible to impart both high hardness and high strength performance, consisting of a compound having two or more isocyanate groups in one molecule, a wax emulsion, and a compound having three or more hydroxyl groups in one molecule. The present invention relates to an adhesive composition for wood fiberboard, and a method for producing a wood fiberboard using the adhesive composition.

  In the production of wood fiberboard, the use of a compound having two or more isocyanate groups in one molecule as an adhesive is already known and widely practiced by those skilled in the art.

  In recent years, wood fiberboard has been required to have high strength that can be used as a structural material in, for example, building materials, and based on a compound having two or more isocyanate groups in one molecule. Studies have been made on the adhesive composition for wood fiber board.

  On the other hand, the present situation is that the wood fiber board is also required to have high hardness to prevent the collapse of the surface layer of the board that occurs when used for various purposes after molding.

  As a technique for imparting high strength to a wood fiberboard, for example, a method of increasing the strength of a wood fiberboard by mixing polyols in advance or at the time of defibration to obtain a uniform adhesive force (see, for example, Patent Document 1) ) Has been proposed.

  However, in this method, the performance of high strength is imparted to the wood fiber board as described above, but not sufficiently imparted until the hardness is increased.

  Moreover, it is assumed that the load on the defibrating apparatus due to the adhesion of the polyol to be mixed increases.

JP 2002-52515 A

  An object of the present invention is to provide an adhesive composition capable of obtaining a wood fiberboard imparted with both high hardness and high strength based on the above-mentioned requirements, and the adhesive composition. It is in providing the manufacturing method of the used wood fiber board.

  As a result of intensive studies, the present inventors have found that an adhesive composition comprising an organic polyisocyanate compound, a wax emulsion, and a specific compound provides a wood fiberboard with both high hardness and high strength. The present invention has been completed.

  That is, this invention is shown by the following (1)-(3).

(1) It consists of an organic isocyanate compound (A) having two or more isocyanate groups in one molecule, a wax emulsion (B), and a compound (C) having three or more hydroxyl groups in one molecule. An adhesive composition for wood fiberboard.

(2) The adhesive composition for wood fiber board according to (1), wherein the compound (C) having 3 or more hydroxyl groups in one molecule has an isocyanurate ring structure in the molecule.

(3) A method for producing a wood fiber board, comprising using the wood fiber board adhesive composition according to (1) or (2).

  With the adhesive composition according to the present invention, it is possible to obtain a wood fiber board excellent in both performance of high hardness and high strength.

  In addition, the production method according to the present invention eliminates the need for mixing the polyol in advance or at the time of defibration, so that the load on the defibrating apparatus is small and the production can be easily performed.

  Hereinafter, the present invention will be described in detail.

  As the organic isocyanate compound (A) having two or more isocyanate groups in one molecule in the present invention, various known polyfunctional aliphatic, alicyclic and aromatic isocyanates can be used. Methylene diisocyanate (HDI), isophorone diisocyanate (IPDI), 4,4-dicyclohexylmethane diisocyanate (H12MDI), tolylene diisocyanate (TDI), crude tolylene diisocyanate, modified tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate (4,4) 4′-MDI), polymeric MDI (crude diphenylmethane diisocyanate, crude MDI, etc .: hereinafter abbreviated as “p-MDI”), modified diphenylmethane diisocyanate (carbodiimide-modified, prepo Mer-modified, etc.), ortho-toluidine diisocyanate (TODI), naphthylene diisocyanate (NDI), xylylene diisocyanate (XDI), and the like lysine diisocyanate (LDI). These can be used alone or as a mixture of two or more. In the present invention, 2,4′-diphenylmethane diisocyanate (2,4 ′) is excellent from the viewpoint that it is excellent in the safety of the working environment in handling and that the wood fiber board can have the highest hardness and the highest strength. -MDI), 2,2'-diphenylmethane diisocyanate (2,2'-MDI), 4,4'-MDI, and p-MDI, which is a mixture of polymethylene polyphenylene polyisocyanate having three or more benzene rings Is preferred.

  Further, as the organic isocyanate compound (A) having two or more isocyanate groups in one molecule in the present invention, a part of the isocyanate groups in the above-mentioned p-MDI may be, for example, polyalkylene glycol monoalkyl ether. Such water-dispersed p-MDI that can be obtained by reacting with a compound having one hydroxyl group in one molecule can also be suitably used.

  Examples of the wax emulsion (B) in the present invention include those containing a wax (B1) and an emulsifier (B2), which have an effect of developing releasability from a hot platen.

  Examples of the wax (B1) include an ester compound composed of a monocarboxylic acid having 9 or more carbon atoms in the fatty chain and an aliphatic monoalcohol having 9 or more carbon atoms in the fatty chain.

  Examples of monocarboxylic acids having 9 or more carbon atoms in the fatty chain include capric acid (decanoic acid), lauric acid (dodecanoic acid), myristic acid (tetradecanoic acid), palmitic acid (hexadecanoic acid), and stearic acid (octadecanoic acid). ), Nonadecanoic acid, arachidic acid (eicosanoic acid), and the isomers thereof. These can be used alone or as a mixture of two or more.

  Examples of the aliphatic monoalcohol having 9 or more carbon atoms in the fatty chain include nonyl alcohol (nonanol), decyl alcohol (decanol), undecyl alcohol (undecanol), lauryl alcohol (dodecanol), tridecyl alcohol (tridecanol). ), Myristyl alcohol (tetradecanol), pentadecanol, cetyl alcohol (hexadecanol), heptadecanol, stearyl alcohol (octadecanol), nonadecanol, eicosanol (arachidyl alcohol) and the isomers thereof Can do. These can be used alone or as a mixture of two or more.

  Examples of the emulsifier (B2) include compounds obtained by addition polymerization of ethylene oxide by a known method alone or in a mixture of the above aliphatic monoalcohol having 9 or more carbon atoms in the fatty chain.

  Examples of the compound (C) having three or more hydroxyl groups in one molecule in the present invention include glycerin, trimethylolpropane, hexanetriol, triethanolamine, pentaerythritol, diglycerin, tetramethylolcyclohexane, and methylglucoside. 2,2,6,6-tetrakis (hydroxylmethyl) cyclohexanol, sorbitol, mannitol, dulcitol, sucrose, tris (2-hydroxyethyl) isocyanurate, tris (2-hydroxypropyl) isocyanurate, tris (2- Hydroxybutyl) isocyanurate, tris (α-methyl-β-hydroxypropyl) isocyanurate and the like can be mentioned. Moreover, polyether polyols obtained by addition polymerization of alkylene oxides such as ethylene oxide, propylene oxide, butylene oxide, etc. can be given as examples. In addition, these can be used individually or in mixture of 2 or more types.

  In the present invention, from the viewpoint that excellent high hardness and high strength can be obtained in the obtained wood fiber board, these compounds (C) having three or more hydroxyl groups in one molecule are used. Of the series of compounds, it is preferable to use a compound having an isocyanurate ring structure in the molecule. Among them, tris (2-hydroxyethyl) isocyanurate represented by the following structural formula is used from the viewpoint that it is excellent in water solubility and can be most stably used in the production of wood fiberboard. Is more preferable.

  Tris (2-hydroxyethyl) isocyanurate is available from the market as “Tanac” manufactured by Nissan Chemical Industries, Ltd. and “Sake” manufactured by Shikoku Chemicals Co., Ltd.

  In the present invention, it is also possible to use a formalin condensation resin as required. The formalin condensation resin that can be used in combination is not particularly limited, and examples thereof include a urea resin, a melamine resin, a urea melamine cocondensation resin, a phenol resin, and a phenolmelamine cocondensation resin. These can be used alone or as a mixture of two or more.

  In the present invention, in view of the environment, when a formalin condensation resin is used, a low formalin type resin (the molar ratio during condensation is formalin / other raw material compounds = 1.0 to 1.1). Are preferably used. In addition, it is preferable to use a formalin catcher agent such as urea or ammonia in combination.

  In the present invention, if necessary, as a catalyst for promoting reaction hardening in the production of wood fiberboard, a tertiary amine catalyst, an amine catalyst having a hydroxyl group, a metal catalyst, etc. It is also possible to use a known urethanization catalyst. These can be used alone or as a mixture of two or more.

  Examples of the tertiary amine catalyst include triethylamine, triethylenediamine, N-methylmorpholine, N-methylimidazole, 1-methylimidazole, 1-ethylimidazole, 1-propylimidazole, 1-cyanoimidazole, 1-cyanomethylimidazole. 1,2-dimethylimidazole, 1,4-dimethylimidazole, 1-methyl-2-ethylimidazole, 1-methyl-4-ethylimidazole, 1-ethyl-2-methylimidazole, 1-ethyl-4-methylimidazole , Pyridine, α-picoline and the like.

  Examples of the amine-based catalyst having a hydroxyl group include monoethanolamine, diethanolamine, triethanolamine, N, N, N′-trimethylaminoethylethanolamine, N, N, N ′, N′-tetramethylhydroxypropylenediamine, and the like. Can be mentioned.

  Examples of the metal catalyst include dibutyltin dilaurate, dioctyltin dilaurate, calcium naphthenate, potassium octylate, tin octylate, octyl and the like.

  In the present invention, further, if necessary, inorganic fillers such as cement, blast furnace slag, gypsum, calcium carbonate, clay, aluminum hydroxide, antimony trioxide, quicklime, slaked lime, bentonite, leveling agent, anti-aging It is also possible to adjust the blending amount of an agent, a heat resistance imparting agent, an antioxidant and the like as appropriate.

  Then, the manufacturing method of a wood fiber board is demonstrated.

  As a raw material of the wood fiber board in the present invention, a wood fiber material, that is, a wood fiber material can be used regardless of whether it is a hardwood or a conifer. In addition, lignocellulosic chips such as sorghum stalk, bagasse, rice husk, hemp, straw, grass, ashi, kenaf, coconut, tree, rubber tree, corn, sawdust and the like can also be used. These can be used alone or as a mixture of two or more.

  The adhesive composition for wood fiber board in the present invention comprises an organic isocyanate compound (A) having two or more isocyanate groups in one molecule, a wax emulsion (B), and three or more hydroxyl groups in one molecule. Each of these raw materials is stirred and mixed using, for example, a static mixer in the adhesive coating step in the manufacturing process of the wood fiber board. The obtained wood fiber board adhesive composition is applied.

  In addition, since some of the compounds exemplified as specific examples of the compound (C) having three or more hydroxyl groups in one molecule are in powder form, generally, they are dissolved in the wax emulsion (B), or An adhesive for wood fiber board is prepared by adding a compound (C) having three or more hydroxyl groups in one molecule to a solution in which water (D) is further added to the wax emulsion (B) as required to obtain a mixture. It is preferable when obtaining a composition.

  In the present invention, wood chips are steamed in a closed container with steam, and the chips are fiberized by a pressure refiner. Subsequently, while passing through a pipe called a blow line, the adhesive composition of the present invention is added and applied during the passage. Thereafter, the fiber coated with the wood fiber board adhesive composition is formed by adjusting to a predetermined moisture content by a drying step, and then hot-pressed using a hot press. With this series of manufacturing methods, the desired wood fiber board of the present invention can be obtained.

  Next, although the detailed usage example of the adhesive composition of this invention is demonstrated, this invention is not limited only to this Example.

Examples 1 and 2 and Comparative Examples 1 to 4
According to the blending ratio shown in Table 1, an organic isocyanate compound (A) having two or more isocyanate groups in one molecule, a wax emulsion (B), and a compound (C) having three or more hydroxyl groups in one molecule The wood fiber board adhesive composition comprising the above and a wood raw material were provided according to the method described below to produce a wood fiber board, and various physical properties were measured. Table 1 shows the blending ratio and the physical property evaluation results.

Water-dispersed p-MDI in Table 1 (isocyanate A1: equivalent to (A) in the present invention): trade name “WC-300 (manufactured by Nippon Polyurethane Industry Co., Ltd.)”
p-MDI (isocyanate A2: equivalent to (A) in the present invention): trade name “WC-220 (manufactured by Nippon Polyurethane Industry Co., Ltd.)”
Wax emulsion (corresponding to (B) in the present invention): Mixture shown below.
Wax: esterified product of stearic acid and stearyl alcohol Emulsifier: ethylene oxide polyaddition product of stearyl alcohol Wax / emulsifier = 100/25
Solid content = 30%
THEIC (corresponding to (C) in the present invention): Tris (2-hydroxyethyl) isocyanurate, trade name “Tanac (manufactured by Nissan Chemical Industries, Ltd.)”

Hot pressing of wood fiberboard:
(1) Molding conditions Board size: 46cm x 46cm
Board thickness: 20mm
Setting density: 0.710 g / cm ³
Wood fiber tree species: hardwood / conifer mixture product moisture content: 8%
Matt moisture content: 10%
Press temperature: 200 ° C
Press pressure: 3MPa
Pressing time: 220 seconds (2) Molding method Using a pressure refiner, a hardwood / conifer mixed chip of the amount shown in Table 1 is defibrated (fibrosis) under the conditions of cooking pressure = 0.7 MPa and cooking temperature = 120 ° C. )did. It was passed through a blow line, and the wood fiber board adhesive composition consisting of isocyanate A1, isocyanate A2, wax emulsion, and THEIC in the amounts shown in Table 1 previously mixed therewith, and water for adjusting the mat moisture content. Was applied to the defibrated material. Subsequently, it was dried by the drying process until the water content of the mat was reached. Thereafter, the wood fibers coated with the adhesive composition were weighed and formed so that the density of the hot-pressed product became the set density, and hot-pressed under the above conditions by hot pressing.

  Various physical property values of the wood fiberboard were measured according to JIS-A5908.

  As shown in Table 1, the wood fiber board using the adhesive composition of the present invention as an example is higher in hardness and strength than the wood fiber board used as a comparative example, and exhibits an excellent value. The effect was confirmed.

  As described above, the wood fiber board adhesive composition according to the present invention provides a wood fiber board having excellent performance of high hardness and high strength. The wood fiberboard obtained by the production method using the adhesive composition is used in fields that have hitherto failed to meet the required performance in terms of high hardness and high strength (for example, structural materials such as building materials). It is possible to expand into fields that have not been developed yet.

The fact that such development is possible means that, from the viewpoint of forest protection, etc., the possibility of recycling wood pieces that will be disposed of after wood processing and used wood that will be disposed of will be greatly expanded in terms of usage. Thus, the significance of the present invention is very great.

Claims (3)

  It consists of an organic isocyanate compound (A) having two or more isocyanate groups in one molecule, a wax emulsion (B), and a compound (C) having three or more hydroxyl groups in one molecule, Adhesive composition for wood fiber board.   The adhesive composition for wood fiber boards according to claim 1, wherein the compound (C) having three or more hydroxyl groups in one molecule has an isocyanurate ring structure in the molecule.   A method for producing a wood fiber board, wherein the adhesive composition for wood fiber board according to claim 1 or 2 is used.