Self-emulsifying polyisocyanate for adhesives for hot-pressed molded articles, adhesive composition for hot-pressed molded articles, and hot-pressed molded articles

Abstract

To provide a self-emulsifying polyisocyanate for an adhesive for a hot-pressed molded body and an adhesive composition for a hot-pressed moded body which contribute to the production of a hot-pressed molded body having excellent curability and high strength.SOLUTION: There is provided a self-emulsifying polyisocyanate for an adhesive for a hot-pressed molded body which contains a first self-emulsifying polyisocyanate which is a reaction product of a first self-emulsifying polyisocyanate precursor and a first polyether compound having an ethylene oxide unit, wherein the first self-emulsifying polyisocyanate precursor is any one or more polyisocyanates selected from the group consisting of an aliphatic diisocyanate, an alicyclic diisocyanate and a modified polyisocyanate thereof, the polyisocyanate contains one or more selected from the group consisting of an isocyanurate bond, an allophanate bond and a urethane bond and the content of the first self-emulsifying polyisocyanate is 8 to 100 mass%.SELECTED DRAWING: None

Description

Technical Field

[0001] The present disclosure relates to a self-emulsifying polyisocyanate for adhesives of thermocompression molded bodies, an adhesive composition for thermocompression molded bodies, and a thermocompression molded body.

Background Art

[0002] As thermocompression molded bodies made of lignocellulose such as wood chips and wood fibers, boards such as particle boards and medium-density fiberboards (MDF) are known. As adhesives for thermocompression molded bodies of base materials made of these wood-based materials or non-wood-based materials, for example, emulsion-type adhesives composed of a self-emulsifying polyisocyanate in which a hydrophilic group is introduced into an organic polyisocyanate and water are used. Wooden boards are not limited to furniture and construction uses, and their range of use has expanded and they are also used for structures in the construction field, and higher strength than before is required. Here, Patent Document 1 discloses a method for producing a thermocompression molded wood board in which a lignocellulose-based material is impregnated in advance with an isocyanuration catalyst and an organic polyisocyanate compound is spray-coated as an adhesive during molding.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, the method for manufacturing a hot-pressed wood-based board described in Patent Document 1 is inefficient because it requires impregnating the substrate with an isocyanurate catalyst. Therefore, there is a strong need for an adhesive composition for hot-pressed molded articles that can achieve both strength and curability without impregnating the substrate with an isocyanurate catalyst during the production of the hot-pressed molded article. Therefore, one aspect of this disclosure is aimed at providing a self-emulsifying polyisocyanate for use as an adhesive for hot-pressed articles, and an adhesive composition for hot-pressed articles, which contribute to the production of hot-pressed articles with excellent curability and high strength. Another aspect of this disclosure is aimed at providing hot-pressed articles with excellent productivity and high strength. [Means for solving the problem]

[0005] According to one aspect of this disclosure, The self-emulsifying polyisocyanate (A) comprises a first self-emulsifying polyisocyanate (a1), The first self-emulsifying polyisocyanate (a1) is The first self-emulsifying polyisocyanate precursor (a1-1), The reaction product of a first polyether compound (a1-2) having an ethylene oxide unit, The first self-emulsifying polyisocyanate precursor (a1-1) is Aliphatic diisocyanates (a1-1-1), and Alicyclic diisocyanates (a1-1-2), and, One or more polyisocyanates selected from the group consisting of (a1-1-3) obtained by modifying these, The polyisocyanate (a1-1-3) contains one or more selected from the group consisting of isocyanurate bonds, allophanate bonds, and urethane bonds. A self-emulsifying polyisocyanate (A) for use as an adhesive for hot-pressed articles is provided, wherein the content of the first self-emulsifying polyisocyanate (a1) is 8% by mass or more and 100% by mass or less in the self-emulsifying polyisocyanate (A).

[0006] According to other aspects of this disclosure, The above self-emulsifying polyisocyanate (A) and An adhesive composition for hot-pressed molded articles is provided, comprising a curing accelerator (B).

[0007] According to yet another aspect of this disclosure, A base material for a hot-pressed molded body, A thermo-molded body is provided, comprising a thermo-cured product of the above-mentioned adhesive composition for thermo-molded bodies, which is formed by bonding a substrate for the thermo-molded body to the body. [Effects of the Invention]

[0008] According to one aspect of this disclosure, a self-emulsifying polyisocyanate for use as an adhesive for hot-pressed articles, and an adhesive composition for hot-pressed articles, can be provided, which contribute to the production of hot-pressed articles with excellent curability and high strength. Furthermore, according to another aspect of this disclosure, a hot-pressed article with excellent productivity and high strength can be provided. [Modes for carrying out the invention]

[0009] The following describes in detail exemplary embodiments for carrying out each aspect of this disclosure.

[0010] <Adhesive composition for hot-pressed molded articles, self-emulsifying polyisocyanate for use as an adhesive for hot-pressed molded articles> [Self-emulsifying polyisocyanate (A)] A self-emulsifying polyisocyanate (A) for adhesives for hot-pressed articles according to one aspect of this disclosure is: The self-emulsifying polyisocyanate (A) comprises a first self-emulsifying polyisocyanate (a1), The first self-emulsifying polyisocyanate (a1) is The first self-emulsifying polyisocyanate precursor (a1-1), The reaction product of a first polyether compound (a1-2) having an ethylene oxide unit, The first self-emulsifying polyisocyanate precursor (a1-1) is An aliphatic diisocyanate (a1-1-1), and An alicyclic diisocyanate (a1-1-2), and Any one or more polyisocyanates selected from the group consisting of polyisocyanates (a1-1-3) obtained by modifying these, The polyisocyanate (a1-1-3) contains any one or more selected from the group consisting of isocyanurate bonds, allophanate bonds, and urethane bonds, The content of the first self-emulsifiable polyisocyanate (a1) is 8% by mass or more and 100% by mass or less in the self-emulsifiable polyisocyanate (A). Further, the adhesive composition for a thermocompression molded body according to one aspect of the present disclosure is The above self-emulsifiable polyisocyanate (A) and A curing accelerator (B), and includes.

[0011] Next, the self-emulsifiable polyisocyanate (A) for an adhesive of a thermocompression molded body and the components of the adhesive composition for a thermocompression molded body will be described.

[0012] [[First self-emulsifiable polyisocyanate (a1)]] The self-emulsifiable polyisocyanate (A) includes the first self-emulsifiable polyisocyanate (a1). The first self-emulsifiable polyisocyanate (a1) is A reaction product of a first self-emulsifiable polyisocyanate precursor (a1-1) and A first polyether compound (a1-2) having an ethylene oxide unit.

[0013] The first self-emulsifiable polyisocyanate precursor (a1-1) is An aliphatic diisocyanate (a1-1-1), and An alicyclic diisocyanate (a1-1-2), and Any one or more polyisocyanates selected from the group consisting of polyisocyanates (a1-1-3) obtained by modifying these.

[0014] Examples of aliphatic diisocyanates (a1-1-1) include hexamethylene diisocyanate, tetramethylene diisocyanate, 2-methylpentane-1,5-diisocyanate, 3-methylpentane-1,5-diisocyanate, lysine diisocyanate, trioxyethylene diisocyanate, and the like.

[0015] Examples of alicyclic diisocyanates (a1-1-2) include isophorone diisocyanate, cyclohexyl diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, norbornane diisocyanate, hydrogenated tolylene diisocyanate, hydrogenated xylene diisocyanate, and hydrogenated tetramethylxylene diisocyanate.

[0016] Polyisocyanate (a1-1-3) is a polyisocyanate (a1-1-3) obtained by modifying an aliphatic diisocyanate (a1-1-1) or an alicyclic diisocyanate (a1-1-2). Polyisocyanate (a1-1-3) contains one or more bonds selected from the group consisting of isocyanurate bonds, allophanate bonds, and urethane bonds. The polyisocyanate (a1-1-3) preferably contains isocyanurate bonds obtained by modifying hexamethylene diisocyanate.

[0017] Aliphatic diisocyanates (a1-1-1), alicyclic diisocyanates (a1-1-2), and polyisocyanates (a1-1-3) obtained by modifying them can be used individually or in combination of two or more.

[0018] As the first self-emulsifying polyisocyanate precursor (a1-1), hexamethylene diisocyanate or a modified version thereof is particularly preferred from the viewpoint of strength development and durability.

[0019] The specific manufacturing method for polyisocyanate (a1-1-3) is described below. Polyisocyanates (a1-1-3) can be produced using diisocyanates as a starting material. For example, they can be produced by removing unreacted diisocyanate monomers after an isocyanuration reaction, allophanation reaction, urethane reaction, etc. Removing unreacted diisocyanates is not strictly necessary, but it is preferable to remove them from the standpoint of odor and other factors.

[0020] • Urethane formation of polyisocyanate (a1-1-3) The reaction time varies depending on the presence or absence of a catalyst and the type of isocyanate, but is generally within 10 hours, preferably 1 to 5 hours. The reaction temperature is 40 to 120°C, preferably 60 to 100°C. Known urethane catalysts can be used in the urethane reaction. Specifically, examples of urethane catalysts include organometallic compounds such as dibutyltin diacetate, dibutyltin dilaurate, and dioctyltin dilaurate; and organic amines such as triethylenediamine and triethylamine, and their salts. These catalysts can be used individually or in combination of two or more.

[0021] • Isocyanuration of polyisocyanates (a1-1-3) The isocyanurate catalyst used in the reaction can be appropriately selected from known catalysts. Examples of isocyanurate catalysts include metal salts of carboxylic acids and tetraalkylammonium salts. Examples of metals that constitute metal salts of carboxylic acids include alkali metals (lithium, sodium, potassium, etc.), alkaline earth metals (magnesium, calcium, barium, etc.), and other typical metals (zinc, tin, lead, etc.). Examples of tetraalkylammonium salts include octylates of tetramethylammonium. These catalysts can be used individually or in combination of two or more.

[0022] The isocyanurate catalyst content is preferably 0.0001% by mass or more and 0.01% by mass or less, relative to the total mass of the diisocyanate and polyol, and more preferably 0.0005% by mass or more and 0.003% by mass or less. If the content is 0.0001% by mass or more, the isocyanurate reaction proceeds more easily and the reaction time can be further reduced. If the content is 0.01% by mass or less, runaway reaction due to rapid exothermic reaction can be further suppressed, and discoloration of the prepolymer and an increase in unwanted viscosity can be further suppressed.

[0023] Here, the isocyanurate reaction is carried out at a reaction temperature of 40 to 80°C, preferably 50 to 70°C. If the reaction temperature is 40°C or higher, the isocyanurate reaction proceeds more easily and the reaction time can be further reduced. If the reaction temperature is 80°C or lower, the formation of polymers can be further suppressed, further reducing the coloration of the prepolymer and further suppressing the increase in unwanted viscosity.

[0024] • Allophanation of polyisocyanate (a1-1-3) The allophanate catalyst used in the reaction can be appropriately selected from known catalysts. Examples of allophanate catalysts include metal salts of carboxylic acids.

[0025] Examples of metals that constitute the metal salts of carboxylic acids include typical metals (zinc, tin, lead, etc.) and transition metals (manganese, iron, cobalt, nickel, copper, zirconium, etc.). These catalysts can be used individually or in combination of two or more. The content of the allophanate catalyst is preferably 0.001% to 0.1% by mass, and more preferably 0.005% to 0.03% by mass, relative to the total mass of the diisocyanate and polyol. A content of 0.001% by mass or more facilitates the allophanate reaction and further reduces the reaction time. A content of 0.1% by mass or less suppresses the formation of by-products such as polyisocyanates containing allophanate groups with high molecular weight and polyisocyanates containing nurate groups, further suppresses the increase in viscosity, and results in higher purity.

[0026] Here, the allophanate reaction is carried out at a reaction temperature of 70 to 150°C, preferably 90 to 130°C. A reaction temperature of 70°C or higher allows the reaction to proceed more easily and further reduces the reaction time. A reaction temperature of 150°C or lower further suppresses the formation of by-products such as polyisocyanates containing allophanate groups with high molecular weight, and further suppresses the unwanted increase in viscosity.

[0027] ·Catalyst poison After the isocyanurate or allophanate reaction, a catalyst poison is added to halt the reaction. In the isocyanuration reaction, it is preferable to add the catalyst poison as soon as the desired NCO content is reached. The timing of adding the catalyst poison in the allophanate reaction is not particularly limited, but it is preferable to add it promptly after the reaction is complete in order to suppress the progress of side reactions.

[0028] Examples of catalyst poisons include inorganic acids such as phosphoric acid and hydrochloric acid, organic acids having sulfonic acid groups, sulfamic acid groups, etc., and their esters, acyl halides, and other known compounds. These catalyst poisons can be used individually or in combination of two or more.

[0029] The amount of catalyst poison varies depending on the type of catalyst poison and catalyst, but it is preferably between 0.5 equivalents and 10 equivalents of the catalyst, and particularly preferably between 0.8 equivalents and 5.0 equivalents. If the amount of catalyst poison is 0.5 equivalents or more, deterioration of storage stability such as a decrease in NCO content, thickening, and discoloration of the obtained polyisocyanate can be further suppressed. If the amount is 10 equivalents or less, discoloration of the polyisocyanate can be further suppressed.

[0030] In the purification process, it is preferable to remove the free, unreacted diisocyanate monomers present in the reaction mixture to a residual content of 1.0% by mass or less, for example, by thin-film distillation at 120-140°C under a high vacuum of 10-100 Pa. A residual content of 1.0% by mass or less further reduces odor and suppresses the deterioration of storage stability.

[0031] Among the polyisocyanates obtained by the above operation, polyfunctional polyisocyanates containing isocyanurate bonds (for example, C-HX, manufactured by Tosoh Corporation) are particularly preferred.

[0032] • Content of the first self-emulsifying polyisocyanate (a1) The content of the first self-emulsifying polyisocyanate (a1) in the self-emulsifying polyisocyanate (A) is 8% by mass or more and 100% by mass or less, and more preferably 20% by mass or more and 80% by mass or less. A polyisocyanate (a1-1-3) content of 8% by mass or more is preferable because it results in excellent flexural strength of the resulting molded article. A polyisocyanate (a1-1-3) content of 80% by mass or less is preferable because it lowers the viscosity of the self-emulsifying polyisocyanate (A) at 25°C before emulsification (for example, making it easier to keep it below 5000 mPa·s).

[0033] The first polyether compound (a1-2) is a polyether compound having an ethylene oxide unit. The first polyether compound (a1-2) preferably contains an average of 5 or more ethylene oxide units. The first polyether compound (a1-2) preferably contains 80% by mass or more of oxyethylene units, and more preferably has an average number of hydroxyl groups per molecule of 1.5 or less. When the oxyethylene unit content is 80% by mass or more, it becomes easier to form a uniform emulsion when emulsifying with water when used as an adhesive, resulting in uniform dispersion on the substrate. Furthermore, when the average number of functional groups is 1.5 or less, emulsion formation is easier, and the reduction in pot life due to thickening, etc., can be further suppressed.

[0034] Examples of the first polyether compounds (a1-2) include polyethylene glycol, polypropylene glycol, and polytetramethylene ether glycol, etc., with a number average molecular weight of 300 to 10,000 and 1 to 5 functional groups, obtained by ring-opening polymerization of ethylene oxide, propylene oxide, butylene oxide, tetrahydrofuran, etc., using initiators described later; and polyether polyols copolymerized therefrom. Examples of the first polyether compounds (a1-2) include polyester ether polyols obtained by using known polyester polyols and polycarbonate polyols as initiators. Examples of initiators include various monoalcohols, glycols, glycol ethers, monoamines, diamines, amino alcohols, water, and urea, all having 1 to 5 functional groups and a number-average molecular weight of 18 to 500. The above compounds may be used individually or as a mixture of two or more.

[0035] [[Second self-emulsifying polyisocyanate (a2)]] The self-emulsifying polyisocyanate (A) preferably further comprises a second self-emulsifying polyisocyanate (a2). The second self-emulsifying polyisocyanate (a2) is, Polyphenylene polymethylene polyisocyanate (a2-1) and, This is the reaction product of a second polyether compound (a2-2) containing an average of 5 or more ethylene oxide units.

[0036] Polyphenylene polymethylene polyisocyanate (a2-1) is a mixture of diphenylmethane diisocyanate (hereinafter also referred to as MDI), which contains two benzene rings and two isocyanate groups, and polynuclear compounds containing three or more benzene rings and three or more isocyanate groups. In addition to these, polyphenylene polymethylene polyisocyanate (a2-1) may also contain small amounts of impurities. Examples of impurities include isocyanate dimers, methylated or chlorinated polynuclear compounds, carbodiimide compounds, or uretonimine compounds. Polyphenylene polymethylene polyisocyanate is also referred to as polymeric MDI. A commercially available example of polyphenylene polymethylene polyisocyanate (a2-1) is MR-200 manufactured by Tosoh Corporation (MDI content 35-45%), which is crude diphenylmethane diisocyanate.

[0037] The second polyether compound (a2-2), which contains an average of 5 or more ethylene oxide units, preferably contains 80% by mass or more of oxyethylene units and has an average of 1.5 or fewer hydroxyl groups per molecule. When the oxyethylene units are 80% by mass or more, it becomes easier to form a uniform emulsion when emulsifying with water when used as an adhesive, resulting in uniform dispersion on the substrate. Furthermore, when the average number of functional groups is 1.5 or less, it becomes easier to form an emulsion, and the reduction in pot life due to thickening, etc., can be further suppressed.

[0038] The second polyether compound (a2-2) may be the same as the first polyether compound (a1-2) described above. Furthermore, the second polyether compound (a2-2) may be identical to or different from the first polyether compound (a1-2).

[0039] [Hardening accelerator (B)]

[0040] The curing accelerator (B) promotes reaction curing with the substrate and reaction curing with water as an adhesive. Examples include a catalyst that promotes reaction curing of the first self-emulsifying polyisocyanate (a1). Examples of catalysts include known urethane catalysts such as tertiary amine catalysts, amine catalysts having hydroxyl groups, and metal catalysts. These urethane catalysts may be used individually or in combination of two or more.

[0041] Examples of tertiary amine catalysts 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, and α-picoline.

[0042] Examples of amine catalysts having hydroxyl groups include monoethanolamine, diethanolamine, triethanolamine, N,N-dimethylethanolamine, N,N,N'-trimethylaminoethylethanolamine, and N,N,N',N'-tetramethylhydroxypropylenediamine.

[0043] Examples of metal catalysts include dibutyltin dilaurate, dioctyltin dilaurate, calcium naphthenate, potassium octoate, tin octoate, and zinc octoate.

[0044] Among these, aliphatic tertiary amine compounds are preferred, and since reactive catalysts suppress emission from the molded article after hot-press molding and allow for easy adjustment of the curing time, aliphatic tertiary amine compounds containing active hydrogen groups are even more preferred, and aliphatic tertiary amines containing hydroxyl groups are particularly preferred.

[0045] The amount of curing accelerator (B) is preferably in proportion to the amount of the first self-emulsifying polyisocyanate (a1) in the self-emulsifying polyisocyanate (A). The content of the curing accelerator (B) is preferably 0.1% by mass or more and 10% by mass or less, and particularly preferably 0.5% by mass or more and 5% by mass or less, relative to the first self-emulsifying polyisocyanate (a1). When the content of the curing accelerator (B) is 0.1% by mass or more, the curing reaction is accelerated, improving productivity by shortening the reaction time, and the physical properties of the hot-pressed molded article tend to be better because sufficient heat and pressure are achieved. When the content of the curing accelerator (B) is 10% by mass or less, the content of the curing accelerator (B) in the adhesive composition for hot-pressed molded articles does not become too high, further suppressing deterioration of adhesive bonding over time and the resulting deterioration of durability that manifests as a decrease in physical properties.

[0046] The adhesive composition is, for example, a two-component mixed adhesive comprising a first liquid containing a self-emulsifying polyisocyanate (A) and a second liquid in which components other than the first liquid have been pre-mixed. In this case, it is preferable that the first liquid is a mixture of a first self-emulsifying polyisocyanate (a1) and a second self-emulsifying polyisocyanate (a2) mixed in a predetermined ratio.

[0047] [Other ingredients] The adhesive composition for hot-pressed molded articles may optionally contain inorganic fillers such as cement, blast furnace slag, gypsum, calcium carbonate, clay, aluminum hydroxide, antimony trioxide, quicklime, slaked lime, and bentonite, as well as leveling agents, flame retardants, anti-aging agents, heat-resistant agents, antioxidants, and the like.

[0048] <Hot-pressed molded body> A hot-pressed article according to one aspect of this disclosure is: A base material for a hot-pressed molded body, The present invention comprises a thermo-cured product of the above-mentioned adhesive composition for thermo-molded articles, which is formed by bonding a base material for the thermo-molded article to the above-mentioned adhesive composition.

[0049] The hot-pressed molded article is obtained by bonding (curing) a substrate for hot-pressed molded articles with the aforementioned adhesive composition. The base material for the hot-pressed molded body is preferably an aggregate of small pieces. The small pieces are prepared, for example, by crushing, cutting, or defibrating the raw material (before it is broken down into smaller pieces). The small pieces are preferably subjected to a drying process before being used for molding. The small pieces constituting the base material are preferably needle-shaped, powder-like, fibrous, or strand-like, and the desired shape is selected depending on the type of molded body. The size of the small pieces constituting the base material is preferably in the range of passing through 4 mesh to 250 mesh. In terms of the shape of the base material, it is particularly preferable that the aggregate of these needle-shaped, powder-like, or fibrous small pieces forms a mat-like structure after sieving. Uncured adhesive composition for hot-pressed molded articles is embedded in the gaps between these aggregated small pieces. When heat and pressure are applied to this, the adhesive composition for hot-pressed molded articles hardens, bonding the small pieces that make up the substrate together.

[0050] Examples of substrates include one selected from the group consisting of wood-based substrates, plant-based substrates, and recycled substrates; or a composite substrate of two or more types.

[0051] Examples of wood-based substrates include (1) aggregates of small pieces such as strand chips, dust chips, and flake chips, which are wood chips; (2) aggregates of small pieces such as laminae; and (3) aggregates of small pieces in a fibrous (wood-based fiber) form. Examples of materials made by hot-pressing the aggregate of (1) include particleboard, oriented strand board (OSB), and wafer board. Examples of materials made by hot-pressing the aggregate of (2) include laminated veneer lumber (LVL), laminated strand lumber (LSL), and parallel strand lumber (PSL). Examples of materials made by hot-pressing the aggregate of (3) include hardboard, medium-density fiberboard (MDF), and insulation board.

[0052] Non-woody substrates include aggregates of small plant-based materials such as fiber (non-woody), sorghum stalks, bagasse, rice husks, hemp, straw, rushes, reeds, coconuts and trees, rubber trees, corn, and sawdust.

[0053] Examples of recycled materials include aggregates of small pieces of waste paper, cloth, etc.

[0054] Among these, lignocellulose-based materials are preferred. These may be used individually (one type) or as a composite substrate combining two or more types.

[0055] The content of the self-emulsifying polyisocyanate (A) is preferably 2% by mass or more and 50% by mass or less, and more preferably 4% by mass or more and 30% by mass or less, relative to the base material for the hot-pressed molded article.

[0056] A method for manufacturing a hot-pressed body is described below with an example. First, the aforementioned adhesive composition for hot-pressed molded articles is applied to the substrate for the hot-pressed molded article. When applying the coating solution, apply one of the following coating solutions, for example, (I) or (II). (I): A coating solution obtained by mixing a mixture of a first self-emulsifying polyisocyanate (a1), a second self-emulsifying polyisocyanate (a2), and a curing accelerator (B) immediately before application to the substrate. (II): A coating solution obtained by emulsifying and mixing a mixture of a first self-emulsifying polyisocyanate (a1) and a second self-emulsifying polyisocyanate (a2) with a system of a curing accelerator (B) and a mixture of water for adjusting the solid content.

[0057] When manufacturing on a continuous line, for example, it can be done according to (1) to (6) below. (1) In advance, A first premixture is prepared by mixing a first self-emulsifying polyisocyanate (a1) and a second self-emulsifying polyisocyanate (a2). Separately, a second premixture is prepared by mixing the curing accelerator (B), the self-emulsifying polyisocyanate (A), and the components other than the curing accelerator (B) with water. (2) Prepare a mixed solution by continuously mixing the first premixture and the second premixture using a static mixer or the like. (3) Apply the resulting mixture to the substrate, (4) The substrate coated with the mixed solution is scattered and deposited to create a deposit, (5) Pre-compress the sediment to create a mat, (6) The mat is heat-pressed to obtain a hot-pressed molded body.

[0058] The hot pressing conditions can be appropriately combined and applied from known forming conditions. Preferred hot pressing conditions include, for example, the following temperature, pressure, and time conditions. Temperature: 100~250℃ Pressure: 1-10 MPa Time (per 1mm thickness): 6-30 seconds More preferably, the following conditions apply. Temperature: 150~230℃ Pressure: 2-5 MPa Time (per 1mm thickness): 6-15 seconds [Examples]

[0059] The present invention will be described more specifically below based on examples and comparative examples, but the present invention is not limited to the following examples. Unless otherwise specified, "parts" and "%" in this text refer to mass.

[0060] [Synthesis of self-emulsifying polyisocyanates] • Synthesis Example 1 Using a 2,000 ml reactor equipped with a stirrer, thermometer, condenser, and nitrogen gas inlet tube, 970 g of polyisocyanate (a1-1) and 30 g of MPEG-400 (a1-2) shown in Table 1 were charged, and the mixture was heated to 80°C and reacted for 3 hours to obtain polyisocyanate (A1). • Synthesis Example 2 Polyisocyanate (A2) was obtained by following the same procedure as in Synthesis Example 1, except that 970g of polyisocyanate (a1-1) was replaced with 970g of polymeric MDI (a2-1), and 30g of MPEG-400 (a1-2) was replaced with 30g of MPEG-700 (a2-2).

[0061] Table 1 shows the types of raw materials, their proportions, and analytical values. Polyisocyanate (A3) was used as is, and polyisocyanate (a1-1) was used as is, and polymeric MDI (a2-1) was used as is, for polyisocyanate (A4).

[0062] [Table 1]

[0063] In Table 1, the details of each ingredient are as follows: • Polyisocyanate (a1-1) Manufactured by Tosoh Corporation, product name C-HX, NCO content = 21.7% • Polymeric MDI (a2-1) Manufactured by Tosoh Corporation, product name: Millionate MR-200, NCO content = 30.5% MPEG-400 (a1-2) Manufactured by Kagaku Chemical Co., Ltd., product name: Surfant MPEG400, polyethylene glycol monomethyl ether 400, number average molecular weight = 400 MPEG-700 (a2-2) Manufactured by Kakaku Chemical Co., Ltd., product name: Surfant MPEG750, polyethylene glycol monomethyl ether 700, number average molecular weight = 700

[0064] The standard formulation viscosities are (A1) and (A2) for emulsions with a solid content of 50%, and (A3) and (A4) for polyisocyanates, respectively.

[0065] [Standard blend viscosity measurement] The viscosity of the standard formulation was measured using the following procedure. (1) Emulsions with a solid content of 50% were prepared using self-emulsifying polyisocyanates (A1) and (A2), which had been preheated to 25°C, and distilled water. (2) The viscosity of emulsions (A1) and (A2), and polyisocyanates (A3) and (A4), which were also temperature-controlled to 25°C, was measured using a Type B viscometer TVB-10M manufactured by Toki Sangyo Co., Ltd. (3) Measurements for (A1), (A2), and (A4) were taken with rotor No. 1 at 30 revolutions, and for (A3) with rotor No. 4 at 60 revolutions.

[0066] [Cureability test] A mixture of the various components listed in Table 2 and water (with a solid content of 50%) was prepared in a 200cc cup to a total of 40g. This mixture was stirred for 30 seconds using a small mixer with a rotation speed of 5000 rpm, and then further stirred with a stirring rod in a 95°C water bath. The time from when the mixture was placed in the water bath until stirring became difficult due to thickening caused by the curing reaction was measured and defined as the curing time.

[0067] [Method for forming hot-pressed articles] Molding conditions Board size: 30cm x 30cm Board thickness: 10mm Setting density: 720kg / m 3 Product moisture content: 9% by mass Mat moisture content: 14% by mass Heating plate (press) temperature: 180℃ Hot plate (press) pressure: 3 MPa (surface pressure) Heating plate (pressing) time: 150 seconds

[0068] The hot-pressed articles listed in Table 2 were prepared by the following method. This method is common to all of the following examples and comparative examples. The amount of base material (wood fiber) listed in Table 2 was placed in a blender with a volume of approximately 50L equipped with stirring blades. The mixture of various components and water for adjusting the water content, also listed in Table 2, was then spray-coated to the blender while mixing and stirring for 5 minutes. After that, the base material coated with the mixture was removed, and the density of the molded body after molding was determined to be the set density (720 kg / m³).3 The material was weighed to the specified size and spread and piled into a frame set to the board size (30cm x 30cm) on a SUS-304 test panel coated with a release agent. Next, a mat was formed by pre-compression and the frame was removed. Then, a test panel of the same shape coated with a release agent was placed on top and hot-pressed under the molding conditions described above.

[0069] [Table 2]

[0070] Curing accelerator (B) Manufactured by Tosoh Corporation, product name TOYOCAT-A30

[0071] [Physical property measurement] The bending strength of the molded articles of Examples 1-5 and Comparative Examples 1-5 in Table 2 was measured in accordance with JIS A-5908.

[0072] Examples 1-5 Self-emulsifying polyisocyanate (a1-1) was mixed with self-emulsifying polyisocyanate (A1) and a curing accelerator (B) at a concentration of 5% relative to the amount of (A1) added. The strength tended to increase as the amount of (A2) substituted for (A1) increased.

[0073] Comparative Examples 1-2 Using the same substrate as in the examples, 5% of self-emulsifying polyisocyanate (a2-1) and 5% of polyfunctional polyisocyanate (A1) were introduced into the binder resin. Both Comparative Examples 1 and 2 had comparable strengths, and their strengths were lower than those of the respective examples.

[0074] Comparative Example 3 In Example 5, molding was carried out in the same manner except that the curing accelerator (B) was not used. As a result, sufficient strength could not be obtained in Comparative Example 3.

[0075] Comparative Example 4 Although only non-self-emulsifying polyisocyanate (A3) was used, its high viscosity prevented spray application to the substrate, making molding impossible.

[0076] Comparative Example 5 Using only non-self-emulsifying polymeric MDI (A4), the molding process was carried out in the same manner. Due to insufficient dispersion on the substrate, numerous glue spots were observed in the molded product, resulting in reduced strength.

Claims

1. A self-emulsifying polyisocyanate (A) for use as an adhesive for hot-pressed articles, The self-emulsifying polyisocyanate (A) comprises a first self-emulsifying polyisocyanate (a1) and a second self-emulsifying polyisocyanate (a2), The first self-emulsifying polyisocyanate (a1) is The first self-emulsifying polyisocyanate precursor (a1-1), The reaction product of a first polyether compound (a1-2) having an ethylene oxide unit, The first self-emulsifying polyisocyanate precursor (a1-1) is Aliphatic diisocyanate (a1-1-1), and Alicyclic diisocyanates (a1-1-2), and, One or more polyisocyanates selected from the group consisting of polyisocyanates (a1-1-3) obtained by modifying these, The second self-emulsifying polyisocyanate (a2) is Polyphenylene polymethylene polyisocyanate (a2-1) and, The reaction product is a second polyether compound (a2-2) having an ethylene oxide unit, The polyisocyanate (a1-1-3) contains one or more selected from the group consisting of isocyanurate bonds, allophanate bonds, and urethane bonds. The content of the first self-emulsifying polyisocyanate (a1) is 25% by mass or more and 75% by mass or less in the self-emulsifying polyisocyanate (A), The content of the second self-emulsifying polyisocyanate (a2) is 25% by mass or more and 75% by mass or less in the self-emulsifying polyisocyanate (A). Self-emulsifying polyisocyanate (A) for use as an adhesive for hot-pressed molded articles.

2. The self-emulsifying polyisocyanate (A) according to claim 1, wherein both the first polyether compound (a1-2) and the second polyether compound (a2-2) contain 80% by mass or more of oxyethylene units and the average number of hydroxyl functional groups per molecule is 1.5 or less.

3. The self-emulsifying polyisocyanate (A) according to claim 2, wherein the first polyether compound (a1-2) and the second polyether compound (a2-2) are different.

4. A self-emulsifying polyisocyanate (A) for use as an adhesive for hot-pressed articles, The self-emulsifying polyisocyanate (A) comprises a first self-emulsifying polyisocyanate (a1), The first self-emulsifying polyisocyanate (a1) is The first self-emulsifying polyisocyanate precursor (a1-1), The reaction product of a first polyether compound (a1-2) having 80% by mass or more of ethylene oxide units, The first self-emulsifying polyisocyanate precursor (a1-1) contains an isocyanurate bond obtained by modifying hexamethylene diisocyanate, A self-emulsifying polyisocyanate (A) for use as an adhesive for hot-pressed articles, wherein the content of the first self-emulsifying polyisocyanate (a1) is 8% by mass or more and 100% by mass or less in the self-emulsifying polyisocyanate (A).

5. A self-emulsifying polyisocyanate (A) according to any one of claims 1 to 4, An adhesive composition for hot-pressed molded articles, comprising a curing accelerator (B).

6. The adhesive composition for a hot-pressed molded article according to claim 5, wherein the content of the curing accelerator (B) is 0.1% by mass or more and 10% by mass or less with respect to the first self-emulsifying polyisocyanate (a1).

7. The adhesive composition for a hot-pressed molded article according to claim 5 or 6, wherein the curing accelerator (B) contains an aliphatic tertiary amine compound.

8. The adhesive composition for a hot-pressed molded article according to claim 7, wherein the curing accelerator (B) is an active hydrogen group-containing aliphatic tertiary amine compound.

9. A base material for a hot-pressed molded body, A hot-pressed molded body comprising a hot-pressed cured product of the adhesive composition for hot-pressed molded bodies according to any one of claims 5 to 8, which is obtained by bonding a base material for the hot-pressed molded body.

10. The hot-pressed molded article according to claim 9, wherein the base material is one selected from the group consisting of wood-based base materials, plant-based base materials, and recycled base materials; or two or more composite base materials.

11. The hot-pressed molded article according to claim 9 or 10, wherein the base material is a lignocellulose-based material.

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