JP2008229878A - Resin for molding high strength lignocellulosic substance - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a hot pressing molded woody board excellent in mechanical strength without damaging storage stability or productivity. <P>SOLUTION: The woody board excellent in mechanical strength is obtained by molding the woody board using an isocyanate group terminal prepolymer, which is obtained by modifying a part of an organic polyisocyanate compound (a) with a hydroxyl group-containing compound (C) having an α, β-unsaturated carbonyl group, as an adhesive. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention is a hot press molding of particle board (PB), oriented strand board (OSB), soft fiber board (insulation board, IB), semi-hard fiber board, MDF, hard fiber board (hard board, HB), etc. In particular, the present invention relates to a method for producing a hot-pressed wood board having excellent mechanical strength.

  Conventionally, urea resin, urea melamine resin, phenol resin, and the like have been used in an extremely large amount as an adhesive for wood and its secondary processed products, plywood, particle board and the like. However, although urea resin is excellent in thermosetting property, it is said that it is inferior in adhesion performance to a substrate having a high water content and water resistance performance as a product. In addition, phenolic resins have poor thermosetting properties, require long-term heat pressure at high temperatures, and are considered difficult to adopt as general-purpose resins in view of energy costs and productivity.

  Recently, in order to solve these drawbacks, it has been tried to use an organic polyisocyanate compound in a mixed system with the above-mentioned resins, and an excellent wood board can be produced. Therefore, a method of using a catalyst in combination is now being studied for the purpose of further improving physical properties.

For example, as shown in Patent Document 1, by using a temperature-sensitive catalyst such as an organic acid salt catalyst of a cyclic amine compound mixed with an organic polyisocyanate compound, the catalyst activity is low at room temperature, and a specific temperature corresponding to the molding temperature. Discloses a method for achieving both the curability and the pot life by exerting catalytic activity. However, because this method cannot mix organic isocyanate and catalyst due to storage stability problems, it must be blended immediately before use or applied to wood at the same time and must be used up shortly after blending. , There is a problem that the management of the formulation becomes complicated. Furthermore, since the crosslinking density of the isocyanate is not different from that of a normal one, there is a problem that a sufficient mechanical strength cannot be obtained.

Japanese Patent Laid-Open No. 11-35918

Furthermore, as disclosed in Patent Document 2, it is disclosed that a wood fiber material is impregnated with an isocyanurate forming catalyst in advance to introduce an isocyanurate bond into the wood board, thereby expressing the mechanical strength of the wood board. ing. However, this method has a problem that it is difficult to increase the productivity because a step of impregnating the wood fiber material with the isocyanurate-forming catalyst in advance is necessary.

Japanese Patent Laid-Open No. 2003-276011

  The problem to be solved by the present invention is to solve the above problems and to provide a method for producing a wooden board having excellent mechanical strength without impairing storage stability and productivity.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have obtained a part of the organic polyisocyanate compound (a) as an adhesive, α, β-unsaturated as a method for solving the above-mentioned problems. It has been found that a wood board having excellent strength can be obtained by molding a wood board using an isocyanate group-terminated prepolymer modified with a hydroxyl group-containing compound (C) having a carbonyl group.

  According to the present invention, the amino group produced after the isocyanate group of the isocyanate group-terminated prepolymer (A) reacts with water (B) is the double of the α, β-unsaturated carbonyl group in the isocyanate group-terminated prepolymer. It becomes possible to highly crosslink by reacting with the bond. Thereby, compared with the case where the normal isocyanate group terminal prepolymer which does not bridge | crosslink is used, it becomes possible to raise the mechanical strength of the wooden board obtained by hot press molding significantly.

That is, the present invention is shown in the following I to III.
I. A method for producing a hot-pressed wood board in which an isocyanate group-terminated prepolymer (A) and water (B) are applied, wherein the isocyanate group-terminated prepolymer (A) comprises an organic polyisocyanate (a) and α, β- A method for producing a hot-pressed wood board, comprising a hydroxyl group-containing compound (C) having a saturated carbonyl group.
II. The method for producing a hot-pressed wood board according to I, wherein the hydroxyl group-containing compound (C) having an α, β-unsaturated carbonyl group is a polyester polyol having an α, β-unsaturated carbonyl group.
III. The hot-press-molded wooden board according to claim 1 or 2, wherein the hydroxyl-containing compound (C) having an α, β-unsaturated carbonyl group is a polyester polyol composed of maleic anhydride, adipic acid and 1,4-butanediol. Production method.

  The present invention provides an isocyanate group-terminated prepolymer (A) composed of an organic polyisocyanate compound (a), a hydroxyl group-containing compound (C) having an α, β-unsaturated carbonyl group, and water (B) in the production of a wood board. By using, a wood board having excellent mechanical properties can be obtained.

  As a raw material for the wood board used 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, straw, grass, kenaf, coconut, rubber tree, corn and sawdust can also be used. Furthermore, it is also possible to use a mixture of these.

  In the present invention, examples of the organic polyisocyanate compound (a) include known 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, xylene-1,4-diisocyanate, xylene-1,3-diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, 2,2'-diphenylmethane diisocyanate, 4,4'-diphenylether diisocyanate, polymethylene polyphenylene polyisocyanate (hereinafter referred to as "polymeric MDI") Abbreviation), 2-nitrodiphenyl-4,4'-diisocyanate, 2,2'-diphenylpropane-4,4'-diisocyanate, 3,3'-dimethyldiphenylmethane-4,4'-diisocyanate, 4,4'- Diphenylpropa Aromatic diisocyanates such as diisocyanate, m-phenylene diisocyanate, p-phenylene diisocyanate, naphthylene-1,4-diisocyanate, naphthylene-1,5-diisocyanate, 3,3'-dimethoxydiphenyl-4,4'-diisocyanate, tetramethylene Aliphatic diisocyanates such as diisocyanate, hexamethylene diisocyanate, 3-methyl-1,5-pentane diisocyanate, lysine diisocyanate, isophorone diisocyanate, hydrogenated tolylene diisocyanate, hydrogenated xylene diisocyanate, hydrogenated diphenylmethane diisocyanate, tetramethylxylene diisocyanate, etc. Alicyclic diisocyanate, its polymer and its polymer, and two or more of these Mixtures thereof.

  In the present invention, the hydroxyl group-containing compound (B) having an α, β-unsaturated carbonyl group is preferably an acrylate ester / methacrylate ester or a polyester polyol.

  Examples of acrylic acid esters and methacrylic acid esters include 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, glycerin diacrylate, triethylene glycol diacrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, glycerin dimethacrylate, tri 1 type, or 2 or more types of mixtures, such as ethylene glycol dimethacrylate, is mentioned.

  The polyester polyol used in the present invention is obtained by dehydration condensation reaction of an α, β-unsaturated polybasic acid or an anhydride thereof with a polyhydric alcohol. Examples of the α, β-unsaturated polybasic acid or anhydride thereof include, for example, maleic acid, fumaric acid, itaconic acid, citraconic acid and the like, and reactive derivatives such as these anhydrides. Or 2 or more types can be used.

  Moreover, when synthesizing these unsaturated polyester polyols, a saturated polybasic acid or an anhydride thereof can be used at the same time. Saturated polybasic acids or their anhydrides include phthalic acid, isophthalic acid, terephthalic acid, tetrahydrophthalic acid, methyltetrahydrophthalic acid, endomethylenetetrahydrophthalic acid, hexahydrophthalic acid, adipic acid, sebacic acid, glutaric acid, hept Examples include acids, tetrabromophthalic acid, trimellitic acid, pyromellitic acid, dimer acid, succinic acid, azelaic acid, rosin-maleic acid adducts and other aromatic carboxylic acids, saturated acids, and derivatives of these anhydrides. Of these, one or more of them can be used.

  Examples of the polyhydric alcohol used when synthesizing these unsaturated polyester resins include dihydric alcohols such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, and tripropylene glycol. , Neopentyl glycol, dibromoneopentyl glycol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,2-pentanediol, 1,3- Aliphatic glycols such as pentanediol, 1,2-hexanediol, 1,4-hexanediol, 1,6-hexanediol and 2,3-hexanediol, fats such as cyclopentanediol, cyclohexanediol and hydrogenated bisphenol A Cyclic All, bisphenol A propylene oxide adduct, aromatic group-containing diols such as p-xylene-α, α'-diol, ethers such as pentaerythritol diallyl ether, trihydric or higher polyhydric alcohols such as glycerin, tri Examples thereof include methylolpropane and pentaerythritol, and one or more of them can be used.

  The isocyanate group-terminated prepolymer (A) used in the present invention comprises an organic polyisocyanate (a) and a hydroxyl group-containing compound (C) having an α, β-unsaturated carbonyl group in a predetermined compounding ratio (isocyanate group / The isocyanate group-terminated prepolymer (A) can be obtained by charging with a hydroxyl group (molar ratio) and reacting at a temperature of 50 to 100 ° C. for 1 to 5 hours. The compounding ratio (isocyanate group / hydroxyl group (molar ratio)) of the organic polyisocyanate (a) and the hydroxyl group-containing compound (C) having an α, β-unsaturated carbonyl group is in the range of 1.5 to 500. In particular, the range of 2 to 400 is particularly preferable. When the equivalent ratio is less than 1.5, the viscosity of the isocyanate group-terminated prepolymer is excessively increased, resulting in problems in workability and the like. Moreover, when this equivalent ratio exceeds 500, since the effect as an isocyanate group terminal prepolymer becomes scarce, it is unpreferable.

  The isocyanate group-terminated prepolymer (A) used in the present invention may be modified with other active hydrogen group-containing compounds in addition to the hydroxyl group-containing compound (C) having an α, β-unsaturated carbonyl group. The active hydrogen group-containing compound is a compound having one or more active hydrogen groups, and examples thereof include long-chain polyols, specifically, saturated polyester polyols, polycarbonate polyols, polyether polyols, and copolyols thereof. . These long chain polyols may be used alone or in combination of two or more. The number average molecular weight of these long-chain polyols is preferably 300 to 10,000.

  Examples of the saturated polyester polyol include known succinic acid, adipic acid, sebacic acid, azelaic acid, terephthalic acid, isophthalic acid, orthophthalic acid, hexahydroterephthalic acid, hexahydroisophthalic acid, hexahydroorthophthalic acid, naphthalenedicarboxylic acid, etc. One or more of dicarboxylic acid, acid ester or acid anhydride and the like, ethylene glycol, 1,3-propylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,3-butanediol, 1, 4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, neopentyl glycol, 1,8-octanediol, 1,9-nonanediol, diethylene glycol, 1,4-cyclohexanedimeta It is obtained by dehydration condensation reaction with one or more of glycols such as ethylene oxide or propylene oxide adduct of bisphenol A, hexamethylene diamine, xylene diamine, isophorone diamine, diamine such as monoethanolamine, or amino alcohol. , Polyester polyol or polyester amide polyol. Moreover, the lactone type | system | group polyester polyol obtained by ring-opening polymerization of cyclic ester (lactone) monomers, such as (epsilon) -caprolactone, is mentioned.

  Examples of the polycarbonate polyol include those obtained by a dealcoholization reaction between a polyhydric alcohol and diethylene carbonate, dimethyl carbonate, diethyl carbonate, diphenyl carbonate, or the like. Examples of the polyhydric alcohol include ethylene glycol, 1,3-propylene glycol, 1,2-propylene glycol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexadiol. Examples include methylenediol, 3-methyl-1,5-pentanediol, neopentyl glycol, 1,8-octanediol, 1,9-nonanediol, diethylene glycol, 1,4-cyclohexanedimethanol and the like.

  As the polyether polyol, polyethylene glycol having a number average molecular weight of 300 to 10,000 having 1 to 5 functional groups obtained by ring-opening polymerization of ethylene oxide, propylene oxide, butylene oxide, tetrahydrofuran or the like using an initiator described later, Polypropylene glycol, polytetramethylene ether glycol, and the like, and polyether polyols obtained by copolymerization thereof, and polyester ether polyols using the above-described polyester polyols and polycarbonate polyols as initiators are also included. As an initiator for obtaining the polyether polyol, various monoalcohols having 1 to 8 functional groups and a number average molecular weight of 18 to 500, glycol, glycol ether, monoamine, diamine, aminoalcohol, water, urea and the like are used. Can do. Said compound can be used individually or in mixture of 2 or more types. As is clear from the above definition, the polyether polyol in the present application includes monool, and alkoxypolyoxyethylene glycol is also included in the polyether polyol, which is advantageous when used as an aqueous adhesive.

  As active hydrogen group-containing compounds other than the hydroxyl group-containing compound (C) having a carbonyl group, short-chain polyols can be suitably used in addition to the above-mentioned long-chain polyols. As the short-chain polyol, those having a molecular weight of 32 to 300 are preferable, and specifically, ethylene glycol, 1,3-propylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,3-butanediol. 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, neopentyl glycol, 1,8-octanediol, 1,9-nonanediol , Diethylene glycol, 1,4-cyclohexanedimethanol, glycols such as ethylene oxide or propylene oxide adducts of bisphenol A, diamines such as hexamethylene diamine, xylene diamine, isophorone diamine, monoethanol amine, amino alcohols, etc. Door can be. Said compound can be used individually or in mixture of 2 or more types.

  The isocyanate group content of the isocyanate group-terminated prepolymer (A) used in the present invention is preferably 5 to 50% by mass, and most preferably 10 to 35% by mass. When the isocyanate group content is 5% by mass or less, the viscosity of the prepolymer becomes high and cannot be applied well to the wood material, and when it is 50% by mass or more, an effect of introducing an α, β-unsaturated carbonyl group is obtained. I can't.

  The unsaturated group concentration in the isocyanate group-terminated prepolymer (A) is preferably 0.03 mmol / g to 3 mmol / g, and more preferably 0.3 mmol / g to 1.5 mmol / g. When the unsaturated group concentration is less than 0.03 mmol / g, the effect of the present invention can be obtained. When the unsaturated group concentration is higher than 3 mmol / g, the viscosity of the isocyanate group-terminated prepolymer (A) becomes too high and good moldability is obtained. There is no problem.

  The proportion of the isocyanate group-terminated prepolymer (A) applied to the wood material is preferably 1 to 20% by mass and more preferably 3 to 10% by mass with respect to the wood material.

  In the process of producing a wooden board according to the present invention, the blending of the isocyanate group-terminated prepolymer (A) and water (B) is carried out in a production method called dry method used in MDF, PB, etc. (A) component / ( Component B) is preferably 10/1 to 1/20, and more preferably 1/2 to 1/5. Moreover, in the wet method used with a hard board (HB) or an insulation board (IB), it is preferable that it is 1/100-1/10000, and it is still more preferable that it is 1/1000-1/5000.

  In the present invention, a formalin condensation resin can be used in combination.

  The formalin condensation resin that can be used in combination is not particularly limited, and examples thereof include urea resins, melamine resins, urea melamine cocondensation resins, phenol resins, and phenol melamine cocondensation resins. These formalin condensation resins may be used alone or in combination of two or more.

  In the present invention, considering the environmental aspect, the formalin condensation resin is a low-formalin type resin (the molar ratio at the time of condensation is formalin / other raw material compounds = 1.0 to 1.1. ) Is preferably used. In addition, it is preferable to use a formalin catcher agent such as urea or ammonia in combination.

  When the above formalin condensation resin is used in combination, the blending ratio is preferably isocyanate group-terminated prepolymer (A) component / formalin condensation resin component = 5/95 to 95/5% by mass, 10/90 to 90. More preferably, it is / 10% by mass.

  In the present invention, as a catalyst for promoting reaction hardening between the isocyanate group-terminated prepolymer (A) and the wood material as a raw material of the wood board, a tertiary amine catalyst, an amine catalyst having a hydroxyl group, and a metal system A known urethanization catalyst such as a catalyst can be used. These urethanization catalysts may be used alone or in combination 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-cyanomethyl. Imidazole, 1,2-dimethylimidazole, 1,4-dimethylimidazole, 1-methyl-2-ethylimidazole, 1-methyl-4-ethylimidazole, 1-ethyl-2-methylimidazole, 1-ethyl-4-methyl Examples include imidazole, pyridine, and α-picoline.

  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. Is mentioned.

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

  In the present invention, as required, inorganic fillers such as cement, blast furnace slag, gypsum, calcium carbonate, clay, aluminum hydroxide, antimony trioxide, quicklime, slaked lime, bentonite, leveling agents, anti-aging agents, A heat resistance imparting agent, an antioxidant and the like can be blended by adjusting the blending amount as appropriate.

  The molding temperature and molding time in the present invention are not particularly limited, and are determined by the material of the wooden board to be used and the physical properties of the target wooden board, but are usually 40 to 230 ° C. and 10 to 600 seconds. The range is preferably 160 to 200 ° C. and 80 to 200 seconds. Similarly, the molding pressure is not particularly limited, and is determined by the material of the wooden board to be used and the physical properties of the target wooden board, but is usually selected from the range of no pressure to 5 MPa.

  Wood boards that can be obtained by the present invention include plywood, particle board (PB), oriented strand board (OSB), soft fiber board (insulation board, IB), semi-rigid fiber board, MDF, hard fiber board ( Hard board, HB) and the like.

  Next, the method for producing a hot-pressed wood board according to the present invention will be described in more detail based on examples. It should be noted that the present invention is not construed as being limited to such examples.

Synthesis example (synthesis of liquid A):
Using a reactor having a capacity of 2,000 ml, equipped with a stirrer, thermometer, cooler and nitrogen gas inlet tube, after charging the types and amounts of raw materials shown in Table 1, the temperature was raised to 80 ° C. 3 By reacting for a time, organic polyisocyanate compounds P1 to P5 were synthesized. The synthesis results are shown in Table 1.

(Raw materials used)
PMDI: Polymeric MDI
Isocyanate content = 31.1%
MDI content in polymeric MDI = 42%
4,4′-MDI content in MDI = 99%
HEA: 2-hydroxyethyl acrylate polyester A: polyester diol obtained from maleic anhydride / adipic acid = 1/1 (molar ratio), 1,4-butanediol
Number average molecular weight = 1,000
MPEG-700: Methoxypolyethylene glycol
Number average molecular weight = 700
Average functional group = 1

Examples 1 and 2 and Comparative Examples 1 and 2
Using the organic polyisocyanate compounds P1, P2, P3, and P4 obtained according to Table 1, MDF was obtained as a wood board. Table 2 shows the evaluation results of the obtained wooden board.

Hot pressing of wood board:
(1) Molding conditions Board size: 46cm x 46cm
Board thickness: 15mm
Setting density: 0.700 g / cm3
Product moisture content: 9%
Matt moisture content: 14%
Hot plate (press) temperature: 180 ° C
Hot plate (press) pressure: 30kg / cm2 (surface pressure)
Hot plate (press) time: 150 seconds (2) Molding method When using wood fiber as a hot-press molded body material, the pressure of the wood chips (conifers) listed in Table 2 using a pressure refiner = 0.7 MPa, cooking temperature = 120 ° C was defibrated (fiberized). It was passed through a pipe, and the amount of the organic polyisocyanate compound shown in Table 2 was spray-coated and then dried until the mat moisture content was obtained to obtain a wood fiber.
When wood chips were used as the pressure-molded body material, wood chips were obtained by spray-coating the amount of organic polyisocyanate compound shown in Table 2 on the amount of wood chips shown in Table 2. Thereafter, the applied wood chip or fiber is taken out and weighed so that the density of the hot-press molded body after molding becomes a set density, and a forming molding apparatus is formed on the following iron plate so as to have the board size. Then, the steel plate having the same shape was placed on top and hot-press molded under the above conditions.

  About the various physical-property value of the wood board of the Example of Table 2, and a comparative example, it measured according to JIS-A5908.

  As shown in Table 2, the wood board introduced with the α, β-unsaturated carbonyl group obtained by the present invention was superior to the wood board without the α, β-unsaturated carbonyl group introduced. Bending strength was obtained.

Claims (3)

A method for producing a hot-pressed wood board in which an isocyanate group-terminated prepolymer (A) and water (B) are applied,
A method for producing a hot-pressed wood board, wherein the isocyanate group-terminated prepolymer (A) comprises an organic polyisocyanate (a) and a hydroxyl group-containing compound (C) having an α, β-unsaturated carbonyl group. The method for producing a hot-pressed wood board according to claim 1, wherein the hydroxyl group-containing compound (C) having an α, β-unsaturated carbonyl group is a polyester polyol having an α, β-unsaturated carbonyl group. The hot-press-molded wooden board according to claim 1 or 2, wherein the hydroxyl-containing compound (C) having an α, β-unsaturated carbonyl group is a polyester polyol composed of maleic anhydride, adipic acid and 1,4-butanediol. Production method.