Coating method

Abstract

To provide a method for uniformly coating a substrate with a moisture-curable polyurethane hot-melt resin.SOLUTION: The coating method includes a coating step of discharging a molten moisture-curable polyurethane hot melt resin 1 from a nozzle device 4 onto a substrate 2 to coat the polyurethane hot melt resin 1 on the substrate 2, and a heating step of heating the polyurethane hot melt resin 1 coated on the substrate 2.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a method for coating a moisture-curable polyurethane hot melt resin onto a substrate. [Background technology]

[0002] Conventionally, a substrate on which electrical components are mounted has been coated with a hot melt resin, and Patent Document 1 discloses the use of a polyolefin hot melt resin as a coating agent.

[0003] However, when using a polyolefin-based hot-melt resin, the temperature of the polyolefin-based hot-melt resin is high when it is applied to the substrate, which raises concerns that the electronic components may be damaged.

[0004] Therefore, Patent Document 2 discloses the use of a moisture-curing polyurethane hot-melt resin as a coating agent to be applied to a substrate. This moisture-curing polyurethane hot-melt resin can be applied to a substrate at a low temperature, thereby preventing damage to electronic components.

[0005] Patent Document 3 also discloses a technique for applying hot melt resin droplets to a substrate with a substantially uniform density distribution. In Patent Document 3, hot melt resin droplets (droplets) adhering to the opening end face of an adhesive hole are blown off and dropped by a pressurized air flow, thereby applying the hot melt resin droplets (droplets) to the substrate. In Patent Document 3, as a droplet (droplet) formed on the opening end face of the adhesive hole falls, the next droplet (droplet) is formed on the opening end face of the adhesive hole and falls, and this process is repeated, so that the droplets (droplets) fall continuously onto the substrate at regular intervals. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-194392 [Patent Document 2] Japanese Patent Application Laid-Open No. 2008-156501 [Patent Document 3] Japanese Patent Application Laid-Open No. 2002-320883 Summary of the Invention [Problem to be solved by the invention]

[0007] However, when using the moisture-curable polyurethane hot-melt resin disclosed in Patent Document 2, the high viscosity of the resin makes it difficult to apply the resin uniformly.

[0008] Furthermore, in Patent Document 3, although hot melt resin particles (droplets) can be applied to a substrate with a uniform density distribution, there are areas on the substrate where no particles (droplets) exist between the particles (droplets). For this reason, Patent Document 3 cannot be said to coat the hot melt resin uniformly on the substrate.

[0009] The present invention has been made in view of the above-mentioned problems, and has as its object to provide a method for uniformly coating a substrate with a moisture-curable polyurethane hot-melt resin. [Means for solving the problem]

[0010] To achieve the above object, the present invention includes the following subject matter.

[0011] Item 1. A coating step of coating a molten moisture-curing polyurethane hot melt resin onto a substrate by discharging the polyurethane hot melt resin from a nozzle device onto the substrate; a heating step of heating the polyurethane hot-melt resin applied to the substrate.

[0012] Item 2. The coating method according to Item 1, wherein in the coating step, a nozzle device is used that blows air discharged from an air nozzle hole onto the molten moisture-curing polyurethane hot-melt resin discharged from a resin nozzle hole, so that the polyurethane hot-melt resin discharged from the nozzle device is applied onto the substrate in the form of particles.

[0013] Item 3. The coating method according to Item 1, wherein the coating step uses a nozzle device that discharges the molten moisture-curable polyurethane hot-melt resin in a line from a resin nozzle hole, so that the polyurethane hot-melt resin discharged from the nozzle device is applied in a line onto the substrate.

[0014] Item 4. The coating method according to any one of Items 1 to 3, wherein in the applying step, the polyurethane hot-melt resin is melted by heating it to a temperature of 100°C or higher and 140°C or lower, and the polyurethane hot-melt resin is discharged from the nozzle device in a state where the viscosity of the polyurethane hot-melt resin is 1000 mPa·s or higher and 5000 mPa·s or lower.

[0015] Item 5. The coating method according to any one of Items 1 to 4, wherein in the heating step, hot air is blown onto the polyurethane hot-melt resin applied to the substrate, thereby heating the polyurethane hot-melt resin.

[0016] Item 6. The coating method according to any one of Items 1 to 4, wherein in the heating step, the polyurethane hot-melt resin applied to the substrate is heated by irradiating the polyurethane hot-melt resin with infrared rays.

[0017] Item 7. The coating method according to any one of Items 1 to 4, wherein in the heating step, the substrate coated with the polyurethane hot-melt resin is placed in a heating furnace and heated, thereby heating the polyurethane hot-melt resin.

[0018] Item 8. The coating method according to any one of Items 1 to 7, wherein the polyurethane hot-melt resin has a number average molecular weight (Mn) of 2,000 or more and 15,000 or less. [Effects of the Invention]

[0019] According to the coating method of the present invention, a moisture-curable polyurethane hot-melt resin can be uniformly coated on a substrate. [Brief explanation of the drawings]

[0020] [Figure 1] 1A is a cross-sectional view showing a substrate coated with a polyurethane hot-melt resin by a coating method according to an embodiment of the present invention, and FIG. 1B is a cross-sectional view showing a substrate coated with a polyurethane hot-melt resin by a coating method according to an embodiment of the present invention. [Figure 2] 1A to 1C are cross-sectional views showing steps of a coating method according to an embodiment of the present invention. [Figure 3] 1 is a cross-sectional view showing a coating head of a nozzle device used in a coating method according to an embodiment of the present invention. [Figure 4] 1A is a cross-sectional view showing the procedure of a coating method according to a modified example of the present invention, and FIG. 1B is a modified view showing the procedure of a coating method according to a modified example of the present invention. [Figure 5] FIG. 10 is a cross-sectional view showing a coating head of a nozzle device used in a coating method according to a modified example of the present invention. [Figure 6] 1 is a graph showing the relationship between viscosity and temperature during heating and cooling of the polyurethane hot-melt resin (AMR-10) used in Examples 1 and 2. [Figure 7] 1 is an image showing a state in which a polyurethane hot-melt resin (AMR-09) is coated on a substrate in Example 4. [Figure 8] 1 is an image showing a state in which a polyurethane hot-melt resin (AMR-09) is coated on a substrate in Comparative Example 1. [Figure 9]1 is an image showing a state in which a polyurethane hot-melt resin (AMR-09) is coated on a substrate in Comparative Example 3. DETAILED DESCRIPTION OF THE INVENTION

[0021] <Embodiment> Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

[0022] Fig. 1(A) is a cross-sectional view showing a substrate 2 coated with polyurethane hot-melt resin 1 by a coating method according to an embodiment of the present invention. Fig. 1(B) is a cross-sectional view showing a substrate 2 coated with polyurethane hot-melt resin 1 by a coating method according to an embodiment of the present invention.

[0023] The coating method according to the embodiment of the present invention is a method for coating a substrate 2 with a moisture-curing polyurethane hot melt resin 1. "Moisture-curing" means "curing by reaction with moisture in the air." In this embodiment, a printed circuit board supporting electrical components 3 (e.g., integrated circuits) is used as the substrate 2, and the polyurethane hot melt resin 1 is coated onto the substrate 2 by a coating method described below so that the electrical components 3 are covered with the polyurethane hot melt resin 1.

[0024] As the polyurethane hot-melt resin 1, a polyurethane resin composition containing a crystalline urethane prepolymer (A) and an amorphous urethane prepolymer (B) can be used.

[0025] Here, the polyurethane hot melt resin in the present invention is also commonly known as a "polyurethane resin composition", "urethane hot melt", "reactive urethane hot melt", "urethane prepolymer", or "isocyanate group-terminated urethane prepolymer".

[0026] Crystalline urethane prepolymer (A) The crystalline urethane prepolymer (A) is not particularly limited, and examples thereof include a compound obtained by reacting a crystalline polyol (C) with an isocyanate compound (D).

[0027] Crystalline polyol (C) The crystalline polyol (C) is not particularly limited as long as it is a crystalline solid at room temperature (25°C). The melting point of the crystalline polyol (C) is preferably 70°C or lower. "Crystalline" means having a crystalline structure at room temperature (25°C).

[0028] The melting points of the crystalline urethane prepolymer (A) and the crystalline polyol (C) are measured by differential scanning calorimetry (DSC). Specifically, they are heated at 20°C / min in an air stream together with a standard sample (alumina powder) and the temperature (°C) at which the maximum endothermic peak is observed can be measured.

[0029] Examples of the crystalline urethane prepolymer include a crystalline urethane prepolymer (A1) obtained by reacting a crystalline polyol (C1) obtained by reacting an aliphatic dicarboxylic acid (E) with an aliphatic diol (F1) and / or a cyclic ether (F2) with an isocyanate compound (D); and a crystalline urethane prepolymer (A2) obtained by reacting a crystalline hydrogenated polyolefin polyol (C2) with an isocyanate compound (D).

[0030] Crystalline polyol (C1) obtained by reacting an aliphatic dicarboxylic acid with an aliphatic diol and / or a cyclic ether The crystalline polyol (C1) is not particularly limited as long as it is a crystalline polyol obtained by reacting an aliphatic dicarboxylic acid with an aliphatic diol and / or a cyclic ether. Specifically, examples of the crystalline polyol (C1) include a crystalline polyol obtained by a condensation reaction between an aliphatic dicarboxylic acid and an aliphatic diol; a crystalline polyol obtained by an esterification reaction between an aliphatic dicarboxylic acid and a cyclic ether; and a crystalline polyol obtained by an esterification reaction between an aliphatic dicarboxylic acid, an aliphatic diol, and a cyclic ether.

[0031] Aliphatic dicarboxylic acids (E) The aliphatic dicarboxylic acid is not particularly limited, and examples thereof include succinic acid, adipic acid, sebacic acid (decanedioic acid), and dodecamethylenedicarboxylic acid. Among these, preferred aliphatic dicarboxylic acids are adipic acid, sebacic acid, dodecamethylenedicarboxylic acid, and 1,12-dodecanedicarboxylic acid, and more preferred is sebacic acid. The dicarboxylic acid may be a derivative of a carboxylic acid. Examples of such derivatives include dialkyl esters, such as dimethyl esters and diethyl esters, of the dicarboxylic acids listed above.

[0032] Aliphatic diol (F1) The aliphatic diol is not particularly limited, and examples thereof include ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 2-methyl-1,4-butanediol, neopentyl glycol, 1,6-hexanediol, 2-methyl-1,5-pentanediol, 3-methyl-1,5-pentanediol, etc. Among these, the aliphatic diol is preferably an aliphatic diol having 2 to 10 carbon atoms, more preferably an aliphatic diol having 4 to 8 carbon atoms, and even more preferably ethylene glycol, 1,4-butanediol, and 1,6-hexanediol.

[0033] Cyclic ether (F2) The cyclic ether is not particularly limited, and examples thereof include oxirane (also called epoxide, ethylene oxide, or alkylene oxide), oxetane, and the like.

[0034] Among these, the crystalline polyol (C1) is preferably a polyester polyol obtained by condensation polymerization using adipic acid or sebacic acid as the aliphatic dicarboxylic acid (E) and an aliphatic diol having 4 to 8 carbon atoms as the aliphatic diol (F1), because the crystalline polyol (C1) provides the crystalline urethane prepolymer with an appropriate melting point and recrystallization (solidification) time, thereby improving workability.

[0035] Crystalline hydrogenated polyolefin polyol (C2) The crystalline hydrogenated polyolefin polyol (C2) is not particularly limited, and examples thereof include hydrogenated polyisoprene polyol and hydrogenated polybutadiene polyol.

[0036] The hydrogenated polyolefin polyol (C2) is not particularly limited, and examples thereof include hydrogenated polybutadiene polyol, hydrogenated polyisoprene polyol, and hydroxyl group-modified polyolefins that can be obtained by reacting an acid-modified polyolefin obtained by modifying a polyolefin with an unsaturated (poly)carboxylic acid (anhydride), as described in JP 2018-076428 A, etc., with an amino alcohol.

[0037] The commercially available crystalline hydrogenated polyolefin polyol (C2) is not particularly limited, and examples thereof include Polytail H (hydrogenated polybutadiene polyol, manufactured by Mitsubishi Chemical Corporation).

[0038] The average hydroxyl value of the crystalline polyol (C1) or the crystalline hydrogenated polyolefin polyol (C2) is usually from 5 to 160 mgKOH / g, preferably from 15 to 1100 mgKOH / g, and more preferably from 20 to 80 mgKOH / g. In the present specification, the "average hydroxyl value" refers to the hydroxyl value of the hydroxyl group-containing compound when the crystalline polyol (C1) or the crystalline hydrogenated polyolefin polyol (C2) is used alone, and refers to the average hydroxyl value calculated by multiplying the hydroxyl values ​​of the hydroxyl group-containing compounds by their blending ratios and adding them up when two or more are used in combination. In the present specification, the hydroxyl value is measured in accordance with Method A of JIS K1557-1:2007.

[0039] The crystalline polyol (C) used in the crystalline urethane prepolymer (A) preferably contains a crystalline polyol (C1) because the difference between the melting point and the freezing point is large, improving workability. In the present invention, the freezing point can be rephrased as the crystallization temperature.

[0040] Isocyanate compounds (D) The isocyanate compound (D) is not particularly limited as long as it has two or more isocyanate groups, and various components that are used or can be used in polyurethane resin compositions can be used.

[0041] The isocyanate compound (D) is not particularly limited and may be, for example, (D1) an aliphatic polyisocyanate compound, (D2) alicyclic polyisocyanate compounds, (D3) Aromatic polyisocyanate compounds Polyisocyanate compounds such as; The modified polyisocyanate compound (D-1) (for example, (d-1a) isocyanurate compound, (d-1b) carbodiimide compound, (d-1c) adduct, (d-1d) Biuret body, (d-1e) allophanate, etc.); Examples thereof include the polynuclear derivatives (D-2) of the above polyisocyanate compounds.

[0042] Examples of the aliphatic polyisocyanate compound (D1) include tetramethylene diisocyanate, dodecamethylene diisocyanate, 1,6-hexamethylene diisocyanate (HDI), 2,2,4-trimethylhexamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, lysine diisocyanate, 2-methylpentane-1,5-diisocyanate, 3-methylpentane-1,5-diisocyanate, and 1,5-pentamethylene diisocyanate, and preferably 1,6-hexamethylene diisocyanate (HDI).

[0043] The (D1) aliphatic polyisocyanate compound is preferably an allophanate-modified or urethane-modified aliphatic polyisocyanate compound (D1a-1). For example, in the present invention, a polyisocyanate compound having an isocyanate group at its terminal, derived from 1,6-hexamethylene diisocyanate (hereinafter abbreviated as "HDI"), can be used. Specific examples of such compounds include Duranate (registered trademark) A201H, D101, D201, TKA-100, TSA-100, TSS-100, TSE-100, and TLA-100, all manufactured by Asahi Chemical Industry Co., Ltd.

[0044] Examples of the (D2) alicyclic polyisocyanate compound include isophorone diisocyanate, hydrogenated xylylene diisocyanate, 4,4'-dicyclohexylmethane diisocyanate (hydrogenated 4,4'-diphenylmethane diisocyanate, HMDI), 1,4-cyclohexane diisocyanate, methylcyclohexylene diisocyanate, and 1,3-bis(isocyanatemethyl)cyclohexane.

[0045] The hydrogenated product of 4,4'-diphenylmethane diisocyanate used in the present invention is a polyisocyanate obtained by hydrogenating 4,4'-diphenylmethane diisocyanate (hereinafter abbreviated as MDI). A specific example of this is WANNATE (registered trademark) HMDI manufactured by Wanka Chemical Japan.

[0046] Examples of the aromatic polyisocyanate compound (D3) include tolylene diisocyanate, 2,2'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, 4,4'-diphenylmethane diisocyanate (MDI), 4,4'-dibenzyl diisocyanate, 1,5-naphthylene diisocyanate, xylylene diisocyanate, 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate, dialkyldiphenylmethane diisocyanate, tetraalkyldiphenylmethane diisocyanate, and α,α,α,α-tetramethylxylylene diisocyanate, and preferred are 2,2'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, and 4,4'-diphenylmethane diisocyanate (MDI). A specific example of such an agent is Millionate (registered trademark) MR-200 (a mixture of MDI and its polynuclear derivatives) manufactured by Tosoh Corporation.

[0047] (D3) An example of the modified aromatic polyisocyanate compound (a) is (d-2) a carbodiimide derivative of 4,4'-diphenylmethane diisocyanate (MDI). In the present invention, a polyisocyanate having a carbodiimide group derived from 4,4'-diphenylmethane diisocyanate (carbodiimide-modified MDI) can be used. A specific example of this is Millionate (registered trademark) MTL manufactured by Tosoh Corporation.

[0048] The viscosity of the isocyanate compound (D) varies depending on the type of isocyanate compound, whether modified, and the like, but is not particularly limited. For example, in the case of aromatic polyisocyanate compounds and their modified products and polynuclear products (preferably carbodiimide and polynuclear aromatic polyisocyanate compounds), the viscosity at 25°C is, for example, 5 to 200 mPa·s, preferably 10 to 150 mPa·s, more preferably 15 to 100 mPa·s, and even more preferably 20 to 80 mPa·s. As another example, in the case of aliphatic polyisocyanate compounds and their modified products and polynuclear products, the viscosity at 25°C is, for example, 100 to 3000 mPa·s, preferably 500 to 2500 mPa·s, more preferably 1000 to 2000 mPa·s, and even more preferably 1200 to 1700 mPa·s.

[0049] The NCO content of the isocyanate compound (D) is not particularly limited, but is, for example, 15 to 45%, more preferably 20 to 40%, and even more preferably 20 to 35%.

[0050] As the isocyanate compound (D), from the viewpoint of excellent moisture resistance and suppressing a decrease in electrical insulation, it is preferable to use (Da-1) an allophanate-modified or urethane-modified polyisocyanate compound (more preferably (D1a-1) an allophanate-modified or urethane-modified aliphatic polyisocyanate compound), (D3) an aromatic polyisocyanate compound (more preferably, 4,4'-diphenylmethane diisocyanate (MDI) or a polynuclear MDI, and a mixture of MDI and a polynuclear MDI); (D3) Carbodiimide derivatives of aromatic polyisocyanate compounds (more preferably, polyisocyanates having carbodiimide groups derived from 4,4'-diphenylmethane diisocyanate (carbodiimide-modified MDI)) are included.

[0051] As the isocyanate compound (D), 4,4'-diphenylmethane diisocyanate or a modified or polynuclear compound thereof is more preferred, and specifically, (D3) an aromatic polyisocyanate compound (more preferably, 4,4'-diphenylmethane diisocyanate (MDI) or a polynuclear MDI, and a mixture of MDI and a polynuclear MDI), and A carbodiimide-modified product of 4,4'-diphenylmethane diisocyanate, that is, a polyisocyanate having a carbodiimide group derived from 4,4'-diphenylmethane diisocyanate (carbodiimide-modified MDI) is more preferred.

[0052] Among these, preferred commercially available isocyanate compounds (D) include, for example, Duranate (registered trademark) D201 (manufactured by Asahi Kasei Corporation), Duranate (registered trademark) A201H (manufactured by Asahi Kasei Corporation), Millionate (registered trademark) MT (manufactured by Tosoh Corporation), Millionate (registered trademark) NM (manufactured by Tosoh Corporation), Millionate (registered trademark) MR-200 (manufactured by Tosoh Corporation), and Millionate (registered trademark) MTL (manufactured by Tosoh Corporation), with Millionate (registered trademark) MT (manufactured by Tosoh Corporation) and Duranate (registered trademark) D201 (manufactured by Asahi Kasei Corporation) being more preferred.

[0053] The isocyanate compound (D) may be used alone or in any combination of two or more kinds.

[0054] The content of the isocyanate compound (D) is not particularly limited as long as it is an amount that can be used in a polyurethane resin composition, and the content is, for example, usually 0.01 to 70 mass%, preferably 0.1 to 50 mass%, more preferably 1 to 40 mass%, and particularly preferably 1.5 to 35 mass%, relative to 100 mass% of the crystalline urethane prepolymer (A). By blending the crystalline urethane prepolymer (A) with the isocyanate compound (D) in the above ratio, foaming caused by carbon dioxide gas during moisture curing is suppressed, while the melt viscosity is reduced, improving workability and electrical insulation. The content of the isocyanate compound (D) is, for example, 5 to 75 parts by mass, preferably 8 to 70 parts by mass, and more preferably 10 to 65 parts by mass, relative to 100 parts by mass of the crystalline polyol (C1) or the crystalline hydrogenated polyolefin polyol (C2).

[0055] When two or more types of isocyanate compounds (D) are blended in the crystalline urethane prepolymer (A), the total amount thereof can be adjusted according to the content of the above-mentioned isocyanate compounds (D).

[0056] When the crystalline urethane prepolymer (A) contains an aromatic polyisocyanate compound (D3), the content thereof is usually 0.01 to 70 mass%, preferably 0.1 to 50 mass%, more preferably 1 to 40 mass%, and particularly preferably 1.5 to 35 mass%, relative to 100 mass% of the crystalline urethane prepolymer (A). By blending the aromatic isocyanate compound (D3) with the crystalline urethane prepolymer (A) in the above ratio, foaming caused by carbon dioxide gas during moisture curing is suppressed, while the melt viscosity is reduced, improving workability and electrical insulation.

[0057] The amount of the (D) isocyanate compound and the crystalline polyol (C1) or the crystalline hydrogenated polyolefin polyol (C2) is such that the NCO / OH ratio (INDEX), which is the ratio of the number of moles of isocyanate groups in the isocyanate compound to the total number of moles of hydroxyl groups in the polyol, is usually in the range of 1.3 to 4, preferably 1.5 to 3.5, and more preferably 1.8 to 3.

[0058] Amorphous urethane prepolymer (B) The amorphous urethane prepolymer (B) is not particularly limited, and examples thereof include amorphous urethane prepolymers obtained by reacting at least one hydroxyl group-containing compound (G) selected from the group consisting of polyether polyols, polyester polyols, polybutadiene polyols, and castor oil polyols with an isocyanate compound (D). The amorphous urethane prepolymer (B) refers to a urethane prepolymer that does not have a regular long-chain molecular structure and does not have a crystalline structure. Among these, amorphous urethane prepolymers are preferably those that are liquid at room temperature (25°C).

[0059] Hydroxyl-containing compounds (G) The hydroxyl group-containing compound (G) is not particularly limited, and examples thereof include (G1) polyether polyol, (G2) polyester polyol, (G3) polycarbonate diol, (G4) polyolefin polyol, and (G5) silicone polyol.

[0060] (G1) Polyether polyol The polyether polyol is not particularly limited, and examples thereof include polyether polyols obtained by addition polymerization of alkylene oxides such as ethylene oxide, propylene oxide, and butylene oxide using as initiators water, low-molecular-weight polyols (propylene glycol, ethylene glycol, glycerin, trimethylolpropane, pentaerythritol, etc.), bisphenols (bisphenol A, etc.), and dihydroxybenzenes (catechol, resorcinol, hydroquinone, etc.). Specific examples thereof include polyethylene glycol, polypropylene glycol, polytetramethylene glycol, propylene oxide adducts of bisphenol A (bisphenol ether polyols), and polyether carbonate diols.

[0061] The hydroxyl value of the polyether polyol (G1) is preferably from 1 to 600 mgKOH / g, more preferably from 10 to 400 mgKOH / g, and particularly preferably from 20 to 150 mgKOH / g.

[0062] The average number of functional groups of the polyether polyol (G1) is usually 1.5 to 5, preferably 2 to 4, and more preferably 1.8 to 2.3.

[0063] The number average molecular weight (Mn) of the polyether polyol (G1) is usually in the range of 100 to 5,000, preferably in the range of 300 to 4,000, and more preferably in the range of 500 to 3,500.

[0064] The (G1) polyether polyols can be used alone or in combination of two or more. Among these, polypropylene diol, polytetramethylene glycol, and propylene oxide adduct of bisphenol A (bisphenol ether polyol) are preferred as the polyether polyol (G1).

[0065] The content of the polyether polyol (G1) is usually 0 to 100 mass%, preferably 0 to 70 mass%, more preferably 1 to 60 mass%, and even more preferably 5 to 50 mass%, relative to 100 parts by mass of the hydroxyl group-containing compound (G).

[0066] (G2) Polyester polyol The polyester polyol (G2) is not particularly limited, and examples thereof include condensation type polyester polyols and castor oil-based polyols.

[0067] Condensation type polyester polyols include aliphatic dicarboxylic acids (succinic acid (C4H6O4), adipic acid (C6H 10 O4), azelaic acid (C9H 16 O4), sebacic acid (C 10 H 18Examples of suitable condensation polyester polyols include polycarboxylic acids having 2 to 10 carbon atoms or esters thereof, and more preferred condensation polyester polyols include polycarboxylic acids obtained by reacting a polycarboxylic acid such as adipic acid, sebacic acid, or isophthalic acid with a diol such as ethylene glycol, propylene glycol, butylene glycol, polyethylene glycol, or polypropylene glycol.

[0068] Specific examples of condensation type polyester polyols include polyethylene adipate diol, polybutylene adipate diol, polyhexamethylene adipate diol, polyethylene terephthalate diol, polyhexamethylene isophthalate diol, polyethylene terephthalate diol, polyhexamethylene terephthalate diol, polyneopentyl terephthalate diol, polyneopentyl adipate diol, polyethylene propylene adipate diol, polyethylene butylene adipate diol, polybutylene Examples of the copolymer include hexamethylene adipate diol, polydiethylene adipate diol, poly(polytetramethylene ether) adipate diol, poly(3-methylpentylene adipate) diol, polyethylene azelate diol, polyethylene sebacate diol, polybutylene azelate diol, polybutylene sebacate diol, poly(butylene adipate / butylene terephthalate) copolymer diol, and poly(3-methylpentylene adipate / 3-methylpentylene terephthalate) copolymer diol.

[0069] Commercially available condensation polyester polyols include, for example, Polylite (registered trademark) OD-X-286, OD-X-102, OD-X-355, OD-X-2330, OD-X-240, OD-X-668, OD-X-2108, OD-X-2376, OD-X-2044, OD-X-688, OD-X-2068, OD-X-2547, and OD-X-2 420, OD-X-2523, OD-X-2555, OD-X-2560, Kuraray Co., Ltd. polyols P-510, P-1010, P-2010, P-3010, P-4010, P-5010, P-6010, F-510, F-1010, F-2010, F-3010, P-1011, P-2011, P-2013, P-2030, N-2010, PNNA-2016; Sun-Estar 2610 [polyethylene adipate diol with Mn=1,000, manufactured by Sanyo Chemical Industries, Ltd.], Sun-Estar 4620 [polytetramethylene adipate diol with Mn=2,000], Sun-Estar 2620 [polyethylene adipate diol with Mn=2,000, manufactured by Sanyo Chemical Industries, Ltd.], Kuraray Polyol P-2010 [poly-3-methyl-1,5-pentylene adipate diol with Mn=2,000], Kuraray Polyol P-3010 [poly-3-methyl-1,5-pentylene adipate diol with Mn=3,000], Kuraray Polyol P-6010 [Poly-3-methyl-1,5-pentylene adipate diol with Mn=6000], Kuraray Polyol P-520 [Poly-3-methyl-1,5-pentylene terephthalate diol with Mn=500], Kuraray Polyol P-1020 [Poly-3-methyl-1,5-pentylene terephthalate diol with Mn=1000], Kuraray Polyol P-2020 [Poly-3-methyl-1,5-pentylene terephthalate diol with Mn=2000], Kuraray Polyol P-530 [Poly-3-methyl-1,5-pentylene isoflurane diol with Mn=500] terephthalate diol], Kuraray Polyol P-1030 [poly-3-methyl-1,5-pentylene isophthalate diol with Mn=1000], Kuraray Polyol P-2030 [poly-3-methyl-1,5-pentylene isophthalate diol with Mn=2000], Kuraray Polyol P-1011 [poly(3-methyl-1,5-pentylene adipate / 3-methyl-1,5-pentylene terephthalate) copolymer diol with Mn=1,000], Kuraray Polyol P-2011 [poly(3-methyl-1,5-pentylene adipate / 3- Examples of suitable poly(3-methyl-1,5-pentylene adipate / 3-methyl-1,5-pentylene isophthalate) copolymer diols include Kuraray Polyol P-1012 [poly(3-methyl-1,5-pentylene adipate / 3-methyl-1,5-pentylene isophthalate) copolymer diols with Mn=1000], Kuraray Polyol P-1012 [poly(3-methyl-1,5-pentylene adipate / 3-methyl-1,5-pentylene isophthalate) copolymer diols with Mn=2000], and Kuraray Polyol P-2050 [poly-3-methyl-1,5-pentylene sebacate diol with Mn=2000].

[0070] The castor oil-based polyol is not particularly limited, and examples thereof include castor oil, castor oil derivatives, etc. As the polyester polyol, castor oil-based polyol is preferred.

[0071] Commercially available castor oil-based polyols include URIC H-1824, URIC H-30, URIC Y-403, URIC HF-1300, URIC HF-2009, and URIC PH-5001 manufactured by Ito Oil Mills, Ltd.

[0072] Examples of castor oil derivatives include castor oil fatty acids, hydrogenated castor oils obtained by hydrogenating castor oil or castor oil fatty acids, transesterification products of castor oil and other fats and oils, reaction products of castor oil and polyhydric alcohols, esterification products of castor oil fatty acids and polyhydric alcohols, and compounds obtained by addition polymerization of these with alkylene oxides. Among the above castor oil-based polyols, it is preferable to use esterification products of castor oil or castor oil fatty acids and polyhydric alcohols.

[0073] Examples of the hydrogenated castor oil include those disclosed in Japanese Patent Application Laid-Open No. 2-298574. Hydrogenated castor oil can be obtained by hydrogenating the above-mentioned castor oil-based polyol.

[0074] The average hydroxyl value of the castor oil-based polyol is preferably 5 to 400 mgKOH / g, and more preferably 10 to 200 mgKOH / g.

[0075] The average number of functional groups in the castor oil-based polyol is usually 1.5 to 3.5, more preferably 1.7 to 3, and even more preferably 1.9 to 2.7.

[0076] The number average molecular weight (Mn) of the above castor oil-based polyol is usually in the range of 100 to 5,000, preferably in the range of 200 to 4,000, and more preferably in the range of 300 to 3,500.

[0077] In this specification, the number average molecular weight (Mn) can be measured by gel permeation chromatography (GPC) (polystyrene equivalent). Specifically, the number average molecular weight by GPC is measured using a Shodex GPC System 21 measuring device manufactured by Showa Denko K.K., a Shodex LF-804 / KF-803 / KF-804 column manufactured by Showa Denko K.K., and NMP as the mobile phase at a column temperature of 40°C, and can be calculated using a calibration curve of standard polystyrene.

[0078] Examples of condensation polyester polyols include polyester polyols obtained by condensing a low-molecular-weight polyol having a number average molecular weight (Mn) of less than 300 with a polycarboxylic acid having 2 to 10 carbon atoms or an ester-forming derivative thereof. Among the low-molecular-weight polyols having a number-average molecular weight (Mn) of less than 300 used in the condensation polyester polyol, preferred are ethylene glycol, propylene glycol, 1,4-butanediol, neopentyl glycol, 1,6-hexane glycol, low-molar adducts of bisphenol A with ethylene oxide (hereinafter abbreviated as "EO") or 1,2- or 1,3-propylene oxide (hereinafter abbreviated as "PO"), and mixtures thereof.

[0079] The average hydroxyl value of the condensation type polyester polyol is preferably from 5 to 400 mgKOH / g, and more preferably from 10 to 200 mgKOH / g.

[0080] The average number of functional groups of the condensation type polyester polyol is usually 1.5 to 3.5, more preferably 1.8 to 3, and even more preferably 2 to 2.7.

[0081] The number average molecular weight (Mn) of the condensation type polyester polyol is usually in the range of 100 to 6,000, preferably in the range of 200 to 5,000, and more preferably in the range of 300 to 4,000.

[0082] The polyester polyols may be used alone or in combination of two or more. The polyester polyol is generally contained in an amount of 0 to 100% by mass, preferably 10 to 95% by mass, and more preferably 20 to 90% by mass, relative to 100% by mass of the hydroxyl group-containing compound (G).

[0083] The hydroxyl group-containing compound is not particularly limited as long as it has an average hydroxyl value of 20 to 150 mgKOH / g and the average functionality can be adjusted to 1.5 to 3.5, and it is possible to use compounds that are conventionally used as polyol components in polyurethane resin compositions.

[0084] (G3) Polycarbonate polyol The polycarbonate polyol is not particularly limited, and examples thereof include reaction products of polyols with carbonate compounds such as dialkyl carbonates, alkylene carbonates, and diaryl carbonates.

[0085] Examples of dialkyl carbonates include dimethyl carbonate and diethyl carbonate. Examples of alkylene carbonates include ethylene carbonate. Examples of diaryl carbonates include diphenyl carbonate. Polycarbonate polyols obtained by polycondensation of the above polyol components with phosgene; polycarbonate polyols obtained by transesterification of the above polyol components with carbonate diesters such as dimethyl carbonate, diethyl carbonate, dipropyl carbonate, diisopropyl carbonate, dibutyl carbonate, ethylbutyl carbonate, ethylene carbonate, propylene carbonate, diphenyl carbonate, and dibenzyl carbonate; copolymer polycarbonate polyols obtained by combining two or more of the above polyol components; polycarbonate polyols obtained by esterification of the above various polycarbonate polyols with carboxyl group-containing compounds; and the above various polycarbonate polyols. Examples of the polycarbonate polyol include polycarbonate polyols obtained by etherifying polyols with hydroxyl group-containing compounds, polycarbonate polyols obtained by transesterification of the above-mentioned various polycarbonate polyols with ester compounds, polycarbonate polyols obtained by transesterification of the above-mentioned various polycarbonate polyols with hydroxyl group-containing compounds, polyester-based polycarbonate polyols obtained by polycondensation of the above-mentioned various polycarbonate polyols with dicarboxylic acid compounds, and copolymerized polyether-based polycarbonate polyols obtained by copolymerizing the above-mentioned various polycarbonate polyols with alkylene oxides. Note that polycarbonate polyols can also be called polycarbonate diols.

[0086] (G4) Polyolefin polyol The polyolefin polyol is not particularly limited, and may be, for example, a polymer of a radically polymerizable monomer having two or more unsaturated double bonds, or a copolymer of such a radically polymerizable monomer with another radically polymerizable monomer, and having two or more hydroxyl groups.

[0087] The polyolefin polyols include polyolefin polyols (for example, polybutadiene polyols, polyisoprene polyols), hydrogenated polyolefin polyols (hydrogenated polyolefin polyols), and the like.

[0088] Examples of polyolefin polyols include polybutadiene polyols, polyisoprene polyols, etc. Commercially available polyolefin polyols include polybutadiene polyols [NISSO-PBG series (G-1000, G-2000, G-3000, etc.) manufactured by Nippon Soda Co., Ltd., Poly Bd (registered trademark) series (R-45M, R-45HT, CS-15, CN-15, etc.) manufactured by ARCO Corporation of the United States, Krasol series (LBH-P2000, LBH 2000, LBH-P3000, LBH 3000, etc.) manufactured by Cray Valley Chemical Industries, Ltd., and polyisoprene polyols [Poly ip manufactured by Idemitsu Kosan Co., Ltd.].

[0089] Examples of hydrogenated polyolefin polyols (hydrogenated polyolefin polyols) include hydrogenated polybutadiene polyols, hydrogenated polyisoprene polyols, etc. Commercially available hydrogenated polyolefin polyols include hydrogenated polybutadiene polyols (NISSO-PBGI series (GI-1000, GI-2000, GI-3000, etc.) manufactured by Nippon Soda Co., Ltd.), Krasol series (HLBH-P2000, HLBH-P 3000, etc.) manufactured by Cray Valley, and hydrogenated polyolefin polyols (EPOL manufactured by Idemitsu Kosan Co., Ltd.).

[0090] The hydroxyl value of the polyolefin polyol is preferably from 10 to 120 mgKOH / g, more preferably from 25 to 110 mgKOH / g, and particularly preferably from 30 to 100 mgKOH / g.

[0091] The average number of functional groups of the polyolefin polyol is usually 1.5 to 5, preferably 1.6 to 3, and more preferably 1.7 to 2.5.

[0092] The number average molecular weight (Mn) of the polyolefin polyol is usually in the range of 100 to 5,000, preferably in the range of 1,000 to 4,000, and more preferably in the range of 1,500 to 3,500.

[0093] The hydroxyl group content of the polyolefin polyol is not particularly limited and is usually 0.001 to 3 mol / kg, preferably 0.01 to 2 mol / kg, and more preferably 0.1 to 1.2 mol / kg.

[0094] The viscosity of the polyolefin polyol (30° C.) is usually in the range of 0.01 to 500 Pa·s, preferably in the range of 0.1 to 300 Pa·s, and more preferably in the range of 1 to 150 Pa·s. do.

[0095] The iodine value of the polyolefin polyol is usually in the range of 1 to 1000 g / 100 g, preferably in the range of 5 to 500 g / 100 g, and more preferably in the range of 10 to 100 g / 100 g.

[0096] The polyolefin polyols may be used alone or in combination of two or more. Among these, polybutadiene polyols are preferred as polyolefin polyols, and polybutadiene polyols having a number average molecular weight (Mn) of 1200 or more and a hydroxyl value of 20 to 150 mgKOH / g are more preferred.

[0097] The content of the polyolefin polyol is preferably 0 to 70 mass %, more preferably 3 to 60 mass %, and even more preferably 5 to 55 mass %, relative to 100 mass % of the hydroxyl group-containing compound (G).

[0098] (G5) Silicone polyol The silicone polyol is not particularly limited, and examples thereof include those in which two or more hydroxyl groups and / or organic groups having a hydroxyl group are introduced into the terminals and / or side chains of dimethylpolysiloxane.Preferred examples of the silicone polyol include carbinol-modified silicone oil, polyether-modified silicone oil, and silanol-modified silicone oil. Commercially available silicone polyols include, for example, "Silaplane FMDA26" manufactured by JNC Corporation, and "Shin-Etsu Silicones" manufactured by Shin-Etsu Chemical Co., Ltd., carbinol-modified types: KF-6000, KF-6001, KF-6002, KF-6003, X-22-170BX, silanol-modified types: X-21-5841, KF-9701, and diol-modified type: X-22-176F.

[0099] As the hydroxyl group-containing compound (G), it is preferable to use at least one selected from the group consisting of polyether polyols, polyester polyols, polybutadiene polyols, and castor oil polyols. The hydroxyl group-containing compound (G) used in the present invention may further contain polyol compounds other than the above (G1) to (G5) (sometimes referred to as other polyols).

[0100] Examples of other polyols include dimer acid polyols, polycarbonate polyols, polycaprolactone polyols, acrylic polyols, amine polyols, and hydrogenated versions of these polyols.

[0101] The dimer acid polyol is not particularly limited, and for example, known dimer acid polyols can be used.

[0102] The polycaprolactone polyol is not particularly limited, and examples thereof include caprolactone-based polyester diols obtained by ring-opening polymerization of cyclic ester monomers such as ε-caprolactone and δ-valerolactone.

[0103] Examples of acrylic polyols include copolymers obtained by copolymerizing a hydroxyl group-containing acrylate with a copolymerizable vinyl monomer copolymerizable with the hydroxyl group-containing acrylate.

[0104] Examples of hydroxyl group-containing acrylates include 2-hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, hydroxybutyl (meth)acrylate, 2,2-dihydroxymethylbutyl (meth)acrylate, polyhydroxyalkyl maleate, and polyhydroxyalkyl fumarate, and preferably 2-hydroxyethyl (meth)acrylate.

[0105] Examples of copolymerizable vinyl monomers include C monomers such as methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, butyl (meth)acrylate, isobutyl (meth)acrylate, s-butyl (meth)acrylate, t-butyl (meth)acrylate, pentyl (meth)acrylate, isopentyl (meth)acrylate, hexyl (meth)acrylate, isononyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and cyclohexyl acrylate. 1-12 Alkyl (meth)acrylate; For example, aromatic vinyls such as styrene, vinyltoluene, and α-methylstyrene; For example, vinyl cyanides such as (meth)acrylonitrile; For example, vinyl monomers containing a carboxyl group, such as (meth)acrylic acid, fumaric acid, maleic acid, and itaconic acid, or alkyl esters thereof; For example, alkane polyol poly(meth)acrylates such as ethylene glycol di(meth)acrylate, butylene glycol di(meth)acrylate, hexanediol di(meth)acrylate, oligoethylene glycol di(meth)acrylate, trimethylolpropane di(meth)acrylate, and trimethylolpropane tri(meth)acrylate; For example, vinyl monomers containing an isocyanate group such as 3-(2-isocyanate-2-propyl)-α-methylstyrene can be used.

[0106] The acrylic polyol can be obtained by copolymerizing these hydroxyl group-containing acrylates and copolymerizable vinyl monomers in the presence of a suitable solvent and a polymerization initiator.

[0107] The acrylic polyol includes, for example, silicone polyol, fluorine polyol, and the like.

[0108] Examples of the fluorine polyol include acrylic polyols blended with a fluorine compound containing a vinyl group, such as tetrafluoroethylene or chlorotrifluoroethylene, as a copolymerizable vinyl monomer in the copolymerization of the acrylic polyol described above.

[0109] The vinyl monomer-modified polyol can be obtained by reacting the above-mentioned high molecular weight polyol with a vinyl monomer.

[0110] The amine polyol is not particularly limited, and examples thereof include diethanolamine, triethanolamine, aliphatic amine polyols, etc. Commercially available aliphatic amine polyols include "Sannyx NP-300" manufactured by Sanyo Chemical Industries, Ltd.

[0111] The freezing point of the hydroxyl group-containing compound (G) is preferably 25°C or lower, more preferably 0°C or lower, and particularly preferably from -5 to -80°C.

[0112] Isocyanate compounds (D) The isocyanate compound (D) to be reacted with the hydroxyl group-containing compound (G) can be the same as the isocyanate compound (D) used in the crystalline urethane prepolymer (A).

[0113] The content of the isocyanate compound (D) is not particularly limited as long as it is an amount that can be used in a polyurethane resin composition, and the content is, for example, usually 0.01 to 50 mass%, preferably 0.1 to 35 mass%, more preferably 1 to 30 mass%, and particularly preferably 1.5 to 25 mass%, relative to 100 mass% of the hydroxyl group-containing compound (G). The content of the isocyanate compound (D) relative to 100 parts by mass of the hydroxyl group-containing compound (G) is, for example, 5 to 75 parts by mass, preferably 8 to 70 parts by mass, and more preferably 10 to 65 parts by mass.

[0114] When two or more types of isocyanate compounds (D) are blended in the amorphous urethane prepolymer (B), the total amount thereof can be adjusted according to the content of the above-mentioned isocyanate compounds (D).

[0115] The amorphous urethane prepolymer (B) is preferably an amorphous urethane prepolymer having an unsaturated bond in its chemical structure. When a polybutadiene polyol and / or a castor oil polyol is used as the hydroxyl group-containing compound (G), these polyols have an unsaturated bond in their structure, and therefore the resulting amorphous urethane prepolymer (B) has an unsaturated bond in its chemical structure, making it possible to obtain a coating film with excellent electrical insulation.

[0116] Other ingredients The polyurethane resin composition of the present invention may further contain various additives, as necessary, such as a polymerization catalyst, a plasticizer, an inorganic filler, an antifoaming agent, a flame retardant, a flame retardant aid, a crosslinking agent (chain extender), an antioxidant, a tackifier, a curing accelerator, a colorant, a filler, a pigment, a bulking agent, an ultraviolet absorber, a moisture absorber, an antifungal agent, and a silane coupling agent.

[0117] polymerization catalyst The polymerization catalyst is at least one selected from the group consisting of organometallic catalysts in which the metal is an element of Group 4 of the periodic table, and reactive amine catalysts.

[0118] Organometallic catalysts, wherein the metal is an element of Group 4 of the periodic table As used herein, the term "organometallic catalyst" refers to a catalyst containing an organic radical and at least one metal, where "organic radical" refers to a radical having at least one carbon atom. The metal of the organometallic catalyst is an element belonging to Group 4 of the periodic table. The elements belonging to Group 4 of the periodic table include titanium, zirconium, hafnium, etc., with zirconium and titanium being preferred. As the organometallic catalyst in which the metal is an element of Group 4 of the periodic table, any zirconium compound or titanium compound that is commonly used as a catalyst in urethanization reactions can be used.

[0119] Examples of organometallic catalysts in which the metal is zirconium (hereinafter also referred to as "organozirconium catalysts") include zirconium alkoxide compounds, acylate compounds, and chelate compounds. Examples of zirconium alkoxide compounds (hereinafter also referred to as "zirconium alkoxides") include zirconium tetra-normal propoxide and zirconium tetra-normal butoxide. Examples of zirconium chelate compounds (hereinafter also referred to as "zirconium chelate complexes") include zirconium tetraacetylacetonate, zirconium dibutoxybis(ethylacetoacetate), zirconium tributoxymonoacetylacetonate, and zirconium monobutoxyacetylacetonate bis(ethylacetylacetonate).

[0120] Examples of organometallic catalysts in which the metal is titanium (hereinafter also referred to as "organotitanium catalysts") include titanium alkoxide compounds and chelate compounds. Examples of titanium alkoxide compounds (hereinafter also referred to as "titanium alkoxides") include titanium tetraisopropoxide, titanium tetra-normal-butoxide, titanium tetra-2-ethylhexoxide, and titanium butoxide dimer. Examples of titanium chelate compounds (hereinafter also referred to as "titanium chelate complexes") include titanium tetraacetylacetonate, titanium diisopropoxybis(acetylacetonate), titanium dioctyloxybis(octylene bricolate), titanium diisopropoxybis(ethyl acetoacetate), titanium diisopropoxybis(triethanolaminate), titanium lactate ammonium salt, and titanium lactate.

[0121] Among the organometallic catalysts, organozirconium catalysts are preferred, zirconium chelate complexes are more preferred, and among the zirconium chelate complexes, zirconium tetraacetylacetonate is more preferred.

[0122] Reactive Amine Catalyst The reactive amine catalyst is an amine catalyst having a functional group in the molecule that reacts with an isocyanate compound. The reactive amine catalyst functions as a catalyst during the production of a polyurethane resin, and simultaneously reacts with the isocyanate compound to immobilize the catalyst in the resin skeleton after curing. Examples of functional groups that react with an isocyanate compound include hydroxyl groups. The reactive amine catalyst is preferably an amine compound containing at least one hydroxyl group in the molecule, such as 2-dimethylaminoethanol, 6-dimethylamino-1-hexanol, 2-[2-(dimethylamino)ethoxy]ethanol, or 1,4-azabicyclo[2.2.2]octane-2-methanol, with 1,4-azabicyclo[2.2.2]octane-2-methanol being preferred.

[0123] The content of the polymerization catalyst may be within a range that does not impair the effect, and is, for example, preferably 0.00001 to 10 mass%, more preferably 0.0001 to 5 mass%, and even more preferably 0.001 to 2 mass%, relative to 100 mass% of the polyurethane resin composition.

[0124] The polymerization catalysts may be used alone or in combination of two or more. The polymerization catalyst may be (i) only an organometallic catalyst in which the metal is a Group 4 element of the periodic table, (ii) only a reactive amine catalyst, or (iii) both an organometallic catalyst in which the metal is a Group 4 element of the periodic table and a reactive amine catalyst. In the case of (i) above, it is preferable to use an organic zirconium catalyst, and it is more preferable to use a zirconium chelate complex. In the case of (ii) above, it is preferable to use 1,4-azabicyclo[2.2.2]octane-2-methanol. In the case of (iii) above, it is preferable to use an organic zirconium catalyst in combination with a reactive amine catalyst.

[0125] The polyurethane resin composition of the present invention may contain, as necessary, a known polymerization catalyst other than an organometallic catalyst in which the metal is an element of Group 4 of the periodic table and a reactive amine catalyst.

[0126] Known polymerization catalysts other than organometallic catalysts in which the metal is an element of Group 4 of the periodic table and reactive amine catalysts include organometallic catalysts in which the metal is an element other than an element of Group 4 of the periodic table; non-reactive amine catalysts; and the like.

[0127] Examples of organometallic catalysts in which the metal is an element other than Group 4 elements of the periodic table include organotin catalysts, organolead catalysts, and organobismuth catalysts. Examples of the organotin catalyst include dioctyltin dilaurate, dibutyltin diacetate, dibutyltin dilaurate, and dioctyltin diacetate. Examples of the organic lead catalyst include lead octoate, lead octenoate, and lead naphthenate. Examples of the organic bismuth catalyst include bismuth octoate and bismuth neodecanoate.

[0128] A non-reactive amine catalyst is an amine catalyst that remains in the product after functioning as a catalyst. Catalysts generally referred to as "amine catalysts" fall into this category. Examples of non-reactive amine catalysts include diethylenetriamine, triethylamine, N,N-dimethylcyclohexylamine, N,N,N',N'-tetramethylethylenediamine, N,N,N',N",N"-pentamethyldiethylenetriamine, trimethylenediamine, dimethylaminoethanol, bis(2-morpholinoethyl)ether, and bis(2-dimethylaminoethyl)ether.

[0129] When a known polymerization catalyst other than an organometallic catalyst in which the metal is an element of Group 4 of the periodic table and a reactive amine catalyst is contained, the content thereof may be within a range that does not impair workability, and is, for example, preferably 0.00001 to 10 mass%, more preferably 0.0001 to 5 mass%, and even more preferably 0.001 to 2 mass%, relative to 100 mass% of the polyurethane resin composition.

[0130] The above-mentioned organometallic catalysts in which the metal is an element of Group 4 of the periodic table and known polymerization catalysts other than reactive amine catalysts can be used alone or in combination of two or more. From the viewpoint of safety for the human body and the environment, it is preferable not to use an organotin catalyst as the polymerization catalyst.

[0131] plasticizer The polyurethane resin composition of the present invention may further contain a plasticizer, if necessary.

[0132] The plasticizer used in the polyurethane resin composition of the present invention is not particularly limited as long as it has a melting point or solidification point of 120°C or less, and examples thereof include ester group-containing plasticizers, phosphorus-based plasticizers, and hydrocarbon-based plasticizers.

[0133] Examples of ester group-containing plasticizers include phthalate ester plasticizers such as dioctyl phthalate, diisononyl phthalate (diisononyl phthalate), and diundecyl phthalate; adipate ester plasticizers such as dioctyl adipate, diisononyl adipate, and diisodecyl adipate; castor oil ester plasticizers such as methyl acetyl ricinoleate, butyl acetyl ricinoleate, acetylated ricinoleic acid triglyceride, and acetylated polyricinoleic acid triglyceride; trimellitic acid esters such as trioctyl trimellitate and triisononyl trimellitate; and pyromellitic acid ester plasticizers such as tetraoctyl pyromellitate and tetraisononyl pyromellitate.

[0134] Examples of phosphorus-based plasticizers include triphenyl phosphate (TPP), tricresyl phosphate (TCP), trixylenyl phosphate (TXP), and cresyl diphenyl phosphate (CDP).

[0135] Examples of hydrocarbon plasticizers include olefinic hydrocarbons such as ethylene and α-olefin co-oligomers, poly-α-olefins, and hydrogenated poly-α-olefins, paraffinic hydrocarbons, naphthenic hydrocarbons, and mixed paraphene-naphthenic hydrocarbons.

[0136] Among these, ester group-containing plasticizers and phosphorus-based plasticizers are preferred, with phosphorus-based plasticizers being more preferred because they not only lower the melt viscosity to improve workability but also impart flame retardancy to the resin.

[0137] When the polyurethane resin composition of the present invention contains a plasticizer, the content of the plasticizer is preferably 0.01 to 50 mass%, more preferably 0.1 to 30 mass%, and particularly preferably 1 to 25 mass%, relative to 100 mass% of the polyurethane resin composition.

[0138] The above plasticizers can be used alone or in combination of two or more.

[0139] inorganic fillers An inorganic filler can be added to the polyurethane resin composition of the present invention as long as the effects of the present invention are not adversely affected.

[0140] The inorganic filler used in the polyurethane resin composition of the present invention is not particularly limited, and examples thereof include metal hydroxides, metal oxides, metal nitrides, natural minerals, zeolites, etc. Furthermore, the surface of the metal oxides, etc. may be treated. Examples of methods for treating the surface of the metal oxides, etc. include oxidation treatment and treatment with a surface treatment agent such as a silane coupling agent.

[0141] Examples of metal hydroxides include aluminum hydroxide, magnesium hydroxide, etc. Here, aluminum hydroxide and magnesium hydroxide also function as flame retardants.

[0142] Examples of metal oxides include aluminum oxide (alumina), magnesium oxide, silicon dioxide (silica, etc.), and titanium oxide.

[0143] Examples of metal nitrides include boron nitride, aluminum nitride, and silicon nitride.

[0144] Examples of natural minerals include calcium carbonate, talc (silicate mineral), mica, kaolin, clay, and silica.

[0145] The zeolite is not particularly limited, and any zeolite used in known polyurethane resin compositions can be used.

[0146] Among these, the zeolite is preferably a crystalline hydrous aluminosilicate of an alkali metal or alkaline earth metal.

[0147] The crystal form of the zeolite is not particularly limited, and examples thereof include A-type, X-type, LSX-type, etc. Among these, the preferred crystal form is A-type.

[0148] The alkali metal or alkaline earth metal in the zeolite is not particularly limited, and examples thereof include potassium, sodium, calcium, lithium, etc. Among these, potassium is preferred.

[0149] The inorganic fillers may be used alone or in combination of two or more.

[0150] When the polyurethane resin composition of the present invention contains an inorganic filler, the content of the inorganic filler is preferably 0.1 to 50 mass %, more preferably 0.3 to 30 mass %, relative to 100 mass % of the polyurethane resin composition.

[0151] The antifoaming agent is not particularly limited, and examples thereof include silicones (oil type, compound type, self-emulsifying type, emulsion type, etc.), alcohols, and the like.

[0152] A preferred silicone-based antifoaming agent is a modified silicone-based antifoaming agent (particularly one in which polysiloxane has a lipophilic group and is modified with a hydrophilic group).

[0153] The above antifoaming agents can be used alone or in combination of two or more.

[0154] When an antifoaming agent is contained, its content is not particularly limited, and is preferably 0.001 to 10 mass %, more preferably 0.005 to 5 mass %, relative to 100 mass % of the polyurethane resin composition.

[0155] Examples of the flame retardant include phosphorus-based flame retardants, inorganic flame retardants, bromine-based flame retardants, and chlorine-based flame retardants.

[0156] Examples of phosphorus-based flame retardants that can be used include red phosphorus, phosphate esters, condensed phosphate esters, aromatic condensed phosphate esters, aliphatic phosphate amidates, and phosphazenes.

[0157] Examples of monomeric aromatic phosphate esters include triphenyl phosphate, tricresyl phosphate, trixylenyl phosphate, tris(isopropylphenyl)phosphate, tris(phenylphenyl)phosphate, trinaphthyl phosphate, cresyl diphenyl phosphate, xylenyl diphenyl phosphate, diphenyl(2-ethylhexyl)phosphate, and di(isopropylphenyl)phenyl phosphate.

[0158] Examples of aromatic condensed phosphate esters include condensed phosphate esters such as trialkyl polyphosphate, resorcinol polyphenyl phosphate, resorcinol poly(di-2,6-xylyl) phosphate, hydroquinone poly(2,6-xylyl) phosphate, and condensates thereof.

[0159] A wide variety of known commercially available aromatic condensed phosphate esters can be used, including, for example, "PX-200" manufactured by Daihachi Chemical Industry Co., Ltd.

[0160] As the inorganic flame retardant, in addition to aluminum hydroxide and magnesium hydroxide described above as inorganic fillers, for example, antimony trioxide, antimony pentoxide, ammonium borate, zinc borate, etc. can be used. Examples of bromine-based flame retardants include hexabromobenzene, decabromodiphenyl oxide (DBDPO), tetrabromobisphenol A (TBBA), and ethylenebis(pentabromophenyl). Examples of chlorine-based flame retardants include chlorinated paraffin, perchlorocyclopentadecanone, and chlorendic acid.

[0161] Examples of the flame retardant aid include nitrogen-based compounds and radical trapping agents such as hindered amines. Examples of the nitrogen-based compound include melamine cyanurate, triazine compounds, and guanidine compounds.

[0162] When the polyurethane resin composition of the present invention contains a flame retardant, the content of the flame retardant or the flame retardant mixture containing the flame retardant and the flame retardant auxiliary is preferably 3 to 30 mass%, more preferably 4 to 25 mass%, and particularly preferably 5 to 20 mass%, relative to 100 mass% of the polyurethane resin composition.

[0163] The crosslinking agent (chain extender) is not particularly limited, and examples thereof include aromatic alcohol-based crosslinking agents such as N,N-bis(2-hydroxypropyl)aniline, hydroquinone-bis(β-hydroxyethyl)ether, and resorcinol-bis(β-hydroxyethyl)ether; and aliphatic alcohol-based crosslinking agents such as ethylene glycol, 1,3-butanediol (1,3-butylene glycol), 1,4-butanediol, octanediol, trimethylolpropane, and triisopropanolamine; aromatic amine-based crosslinking agents such as phenylenediamine, tolylenediamine, diphenyldiamine, 4,4'-diaminodiphenylmethane, 3,3'-dichloro-4,4'-diaminodiphenylmethane, 1,2-bis(2-aminophenylthio)ethane, and trimethylene glycol-p-aminobenzoate; Examples of the crosslinking agents include aliphatic amine-based crosslinking agents such as ethylenediamine, propylenediamine, hexamethylenediamine, and diethylenetriamine.

[0164] Among these, aromatic alcohol-based crosslinking agents and aliphatic alcohol-based crosslinking agents are preferred, and aliphatic alcohol-based crosslinking agents are more preferred.

[0165] The number average molecular weight of the crosslinking agent is usually 1,000 or less, preferably 500 or less, and more preferably 400 or less.

[0166] When the polyurethane resin composition of the present invention contains a crosslinking agent, the content of the crosslinking agent is not particularly limited, and is, for example, usually 0.01 to 30 mass %, preferably 0.1 to 20 mass %, and more preferably 1 to 15 mass %, relative to 100 mass % of the polyurethane resin composition.

[0167] The above crosslinking agents can be used alone or in combination of two or more.

[0168] The content of these components may be appropriately determined depending on the intended use from the range of the usual amounts added and the identification thereof so as not to impair the desired properties of the polyurethane resin composition.

[0169] 2. Method for producing polyurethane resin composition The method for producing the polyurethane resin composition of the present invention is not particularly limited, and the composition can be produced according to any known method used for producing polyurethane resin compositions. For example, the method for producing the polyurethane resin composition of the present invention comprises a step of mixing a crystalline urethane prepolymer (A) and an amorphous urethane prepolymer (B).

[0170] The urethane prepolymer used in the present invention can be produced by known methods. For example, the crystalline urethane prepolymer (A) can be produced by reacting the isocyanate compound (D) in a reaction vessel with a crystalline polyol (C1) obtained by reacting an aliphatic dicarboxylic acid (E) from which moisture has been removed with an aliphatic diol (F1) and / or a cyclic ether (F2). Alternatively, the crystalline urethane prepolymer (A) can be produced by reacting the isocyanate compound (D) in a reaction vessel with a crystalline hydrogenated polyolefin polyol (C2) from which moisture has been removed. The amorphous urethane prepolymer (B) can also be produced by reacting the isocyanate compound (D) in a reaction vessel with at least one hydroxyl group-containing compound (G) selected from the group consisting of polyether polyols, polyester polyols, polybutadiene polyols, and castor oil polyols from which moisture has been removed.

[0171] The crystalline urethane prepolymer (A) and the amorphous urethane prepolymer (B) can usually be produced without a solvent, but they may also be produced by reacting them in an organic solvent. When the reaction is carried out in an organic solvent, an organic solvent such as ethyl acetate, n-butyl acetate, methyl ethyl ketone, or toluene that does not inhibit the reaction can be used, but it is necessary to remove the organic solvent by a method such as heating under reduced pressure during or after the reaction.

[0172] The crystalline urethane prepolymer (A) is preferably reacted in such a manner that the equivalent ratio of the isocyanate groups of the polyisocyanate (D) to 1 equivalent of the hydroxyl groups of the crystalline polyol (C1) or the crystalline hydrogenated polyolefin polyol (C2) is in the range of 1.2 to 5.0, more preferably 1.5 to 3.0. The amorphous urethane prepolymer (B) is preferably reacted in such a manner that the equivalent ratio of the isocyanate groups of the polyisocyanate (D) to 1 equivalent of the hydroxyl groups of the hydroxyl group-containing compound (G) is in the range of 1.2 to 5.0, more preferably 1.5 to 3.0.

[0173] When producing the crystalline urethane prepolymer (A) and the amorphous urethane prepolymer (B), a urethane-forming catalyst or the like can be used as needed. The urethane-forming catalyst or the like can be added appropriately at any stage of the reaction.

[0174] The crystalline urethane prepolymer (A) may contain the above-mentioned other components in addition to the isocyanate compound (D), the crystalline polyol (C1) or the crystalline hydrogenated polyolefin polyol (C2). The amorphous urethane prepolymer (B) may contain the above-mentioned other components in addition to the isocyanate compound (D) and the hydroxyl group-containing compound (G).

[0175] Another example of a method for producing the polyurethane resin composition of the present invention is a method in which the crystalline polyol (C1) or the crystalline hydrogenated polyolefin polyol (C2) and the hydroxyl group-containing compound (G) are mixed and dehydrated, and then the isocyanate compound (D) is added and reacted. The crystalline polyol (C1) or the crystalline hydrogenated polyolefin polyol (C2) is preferably mixed with the hydroxyl group-containing compound (G) at a temperature of about 90 to 120° C. under reduced pressure. The reaction between the resulting mixture and the isocyanate compound (D) is preferably carried out under a nitrogen gas flow. The reaction temperature is usually about 90 to 110°C, preferably about 100°C, and the reaction time is usually about 1 to 3 hours, preferably about 2 hours.

[0176] When producing a polyurethane resin composition, the amount of the crystalline urethane prepolymer (A) is usually 1 to 1000 parts by mass, preferably 10 to 200 parts by mass, and more preferably 25 to 150 parts by mass per 100 parts by mass of the amorphous urethane prepolymer (B).

[0177] The content of the crystalline urethane prepolymer (A) in the polyurethane resin composition is preferably 5 to 80 mass %, more preferably 8 to 65 mass %, and particularly preferably 10 to 50 mass %, relative to 100 mass % of the polyurethane resin composition.

[0178] The content of the amorphous urethane prepolymer (B) in the polyurethane resin composition is preferably 1 to 90 mass %, more preferably 3 to 75 mass %, and particularly preferably 5 to 60 mass %, relative to 100 mass % of the polyurethane resin composition.

[0179] Furthermore, the polyurethane resin composition of the present invention has a melting point of 70° C. or lower and a freezing point of 0° C. to 40° C. The melting point is preferably 40° C. to 70° C., and more preferably 45° C. to 65° C. The freezing point is preferably 2° C. to 38° C., and more preferably 5° C. to 35° C.

[0180] The melting point of the polyurethane resin composition is measured by differential scanning calorimetry (DSC). Specifically, the temperature is increased at 20°C / min in an air stream together with a standard sample (alumina powder), and the temperature (°C) at which the maximum endothermic peak is observed is measured. The freezing point is measured by differential scanning calorimetry (DSC) by cooling the sample in an air stream together with a standard sample (alumina powder) from 120°C at a rate of 20°C / min, and detecting the temperature (°C) at which the maximum endothermic peak is reached.

[0181] The polyurethane resin composition of the present invention has a melt viscosity of 5000 mPa·s or less at 120°C, resulting in excellent castability. Furthermore, since the crosslinking reaction is accelerated over time after solidification, the composition has excellent high-temperature flow resistance and insulation reliability. The melt viscosity (120° C.) of the polyurethane resin composition of the present invention is usually 100 to 5000 mPa·s, preferably 200 to 4000 mPa·s, and more preferably 300 to 3800 mPa·s.

[0182] The solidification time of the polyurethane resin composition of the present invention is not particularly limited, but is preferably 5 to 400 seconds, more preferably 10 to 350 seconds, and particularly preferably 15 to 300 seconds.

[0183] The volume resistivity of the polyurethane resin composition of the present invention is not particularly limited, but Preferably 1 x 10 7 ~1×10 18 Ω m, More preferably 5 × 10 10 ~1×10 17 Ω·m, Particularly preferably 1 × 10 11 ~1×10 16 Ω·m.

[0184] The polyurethane resin composition of the present invention has an isocyanate group at the polymer terminal or within the molecule, which is capable of forming a crosslinked structure upon reaction with moisture present in the air or in a housing, adherend, or the like to which the polyurethane resin composition is applied. Therefore, the polyurethane resin composition of the present invention can form a coating layer (coating film) by reacting with moisture. In the polyurethane resin composition of the present invention, the equivalent ratio ([NCO / OH]) of the isocyanate groups in the polyisocyanate (D) to 1 equivalent of the hydroxyl groups in the crystalline polyol (C) or the hydroxyl group-containing compound (G) is preferably in the range of 1.2 to 5.0, more preferably 1.5 to 3.0.

[0185] In the present invention, for example, a moisture-curable polyurethane hot-melt resin having a number-average molecular weight (Mn) of 2,000 or more and 15,000 or less can be used as the polyurethane hot-melt resin 1. Examples of polyurethane hot-melt resins 1 having a number-average molecular weight (Mn) within the above range include AMR-06, AMR-09, and AMR-10 manufactured by Sanyu Rec Co., Ltd. Table 1 below shows the melting points and melt viscosities at 120°C of AMR-06, AMR-09, and AMR-10. Note that a moisture-curable polyurethane hot-melt resin having a number-average molecular weight (Mn) outside the above range (2,000 or more and 15,000 or less) may also be used to coat a substrate.

[0186] [Table 1]

[0187] FIG. 2 is a cross-sectional view showing the procedure of a coating method according to an embodiment of the present invention. In the coating method according to an embodiment of the present invention, first, a coating step is carried out in which molten moisture-curing polyurethane hot-melt resin 1 is discharged onto substrate 2 from a nozzle device 4 to coat the polyurethane hot-melt resin 1 on substrate 2 (the leftmost drawing in FIG. 2 shows the state during the coating step, and the second drawing from the left in FIG. 2 shows the state after the coating step is completed). In this coating step, polyurethane hot-melt resin 1 is coated on substrate 2 so that it adheres to the "surface of electrical component 3" and the "surface of substrate 2 around electrical component 3."

[0188] 3 is a cross-sectional view showing the coating head of a nozzle device 4 used in a coating method according to an embodiment of the present invention. In the coating process, as shown in FIG. 3, a nozzle device 4 is used that "blows air 7 discharged from an air nozzle hole 6 onto molten moisture-curing polyurethane hot melt resin 1 discharged from a resin nozzle hole 5," so that the polyurethane hot melt resin 1 discharged from the nozzle device 4 is applied in particulate form onto a substrate 2. From the viewpoint of ensuring good drainage of the polyurethane hot melt resin 1 and ensuring reliable application of the polyurethane hot melt resin 1 in particulate form, it is preferable to use a polyurethane hot melt resin 1 having a number average molecular weight (Mn) of 2,000 or more and 15,000 or less.

[0189] As the nozzle device 4 (a nozzle device that blows air 7 discharged from an air nozzle hole 6 onto molten moisture-curing polyurethane hot melt resin 1 discharged from a resin nozzle hole 5), for example, a nozzle device (e.g., a curtain spray nozzle manufactured by Suntool Co., Ltd.) that can send and discharge molten moisture-curing polyurethane hot melt resin 1 between the pitches of a nozzle device shim and blow air from both sides onto the discharged polyurethane hot melt resin 1, causing the discharged polyurethane hot melt resin 1 to fall in a mesh-like pattern, or a nozzle device (e.g., a spiral spray nozzle manufactured by Suntool Co., Ltd.) that can pressurize molten moisture-curing polyurethane hot melt resin 1 into the gun and use the air pressure to raise a needle inside the gun, sending and discharging the polyurethane hot melt resin 1 into the nozzle, and blowing rotation-controlled air onto the discharged polyurethane hot melt resin 1, causing the discharged polyurethane hot melt resin 1 to fall along a spiral rotation trajectory, can be used.

[0190] In the above-mentioned application process, in order to apply the polyurethane hot-melt resin 1 uniformly and without voids onto the substrate 2, the polyurethane hot-melt resin 1 is preferably melted by heating it to a temperature of 100°C or higher and 140°C or lower, and the polyurethane hot-melt resin 1 is then ejected from the resin nozzle hole 5 of the nozzle device 4 in a state in which the viscosity of the polyurethane hot-melt resin 1 is set to a temperature of 1000 mPa.s or higher and 5000 mPa.s or lower.

[0191] Furthermore, the above-mentioned "heating the polyurethane hot-melt resin 1 to a temperature of 100°C or higher and 140°C or lower" can be achieved, for example, by heating the polyurethane hot-melt resin 1 supplied to the nozzle device 4 with a heater provided in the application head of the nozzle device 4. Alternatively, the polyurethane hot-melt resin 1 may be heated to a temperature of 100°C or higher and 140°C or lower by a heater provided outside the nozzle device 4 and melted, and then supplied to the nozzle device 4 and discharged from the nozzle device 4.

[0192] After the application step, a heating step is performed to heat the polyurethane hot-melt resin 1 applied to the substrate 2 (the second drawing from the right in FIG. 2 shows the state during the heating step, and the rightmost drawing in FIG. 2 shows the state after the heating step is completed). This heating step softens the polyurethane hot-melt resin 1 that has been cooled after application to the substrate 2. In this heating step, the polyurethane hot-melt resin 1 applied to the substrate 2 is preferably heated so that the viscosity of the polyurethane hot-melt resin 1 applied to the substrate 2 is 800 mPa s or more and 30,000 mPa s or less, more preferably 1,000 mPa s or more and 25,000 mPa s or less, and particularly preferably 1,200 mPa s or more and 20,000 mPa s or less. By controlling the viscosity of the polyurethane hot-melt resin 1 applied to the substrate 2 within the above range, it is possible to prevent the polyurethane hot-melt resin 1 applied to the substrate 2 from spilling out of the substrate 2 and leaking to the outside when it wets and spreads, while also reducing the number of voids and bubbles that occur in the polyurethane hot-melt resin 1.

[0193] In this embodiment, in the heating step, hot air 8 emitted from a heat source 7 (such as a dryer) is blown onto the polyurethane hot melt resin 1 applied to the substrate 2, thereby heating the polyurethane hot melt resin 1.

[0194] According to the coating method of this embodiment described above, the polyurethane hot melt resin 1 applied to the substrate 2 in the application step is wetted and spread (leveled) by the heat in the heating step. This allows the polyurethane hot melt resin 1 to be evenly coated on the substrate 2. Furthermore, by performing the heating step, voids and bubbles that have occurred in the polyurethane hot melt resin 1 can be reduced.

[0195] In the application process, the amount of polyurethane hot melt resin 1 applied to the substrate 2 and the position on the substrate 2 where the polyurethane hot melt resin 1 is applied are adjusted so that the electrical components 3 are covered with the polyurethane hot melt resin 1 when the heating process is completed.

[0196] The present invention is not limited to the above-described embodiment, and various modifications can be made.

[0197] For example, in the coating process, instead of the nozzle device 4 shown in the above embodiment, a nozzle device 10 may be used that discharges molten moisture-curing polyurethane hot-melt resin 1 in a linear form from a resin nozzle hole 9, as shown in FIG. 4 (FIG. 4 is a cross-sectional view showing the coating head of the nozzle device 10). In this case, as shown in Figure 5, in the coating process, polyurethane hot melt resin 1 is discharged from a resin nozzle hole 9 of a nozzle device 10 and coated linearly onto a substrate 2. Following this coating process, a heating process is carried out in which hot air 8 from a heat source 7 (such as a dryer) is blown onto the polyurethane hot melt resin 1 coated on the substrate 2 to heat the polyurethane hot melt resin 1 coated on the substrate 2. (The leftmost figures in Figures 5(A) and 5(B) show the state when the coating process is being carried out, the second-left figures in Figures 5(A) and 5(B) show the state when the coating process is completed, the second-right figures in Figures 5(A) and 5(B) show the state when the heating process is being carried out, and the rightmost figures in Figures 5(A) and 5(B) show the state when the heating process is completed.) In the modified coating method shown in Figure 5, the amount of polyurethane hot melt resin 1 applied to the substrate 2 in the application process and the position on the substrate 2 where the polyurethane hot melt resin 1 is applied are adjusted so that the electrical components 3 are covered with the polyurethane hot melt resin 1 when the heating process is completed.

[0198] The nozzle device 10 may be, for example, a nozzle device capable of ejecting molten moisture-curing polyurethane hot melt resin 1 from between the pitches of the nozzle device shim while stretching it along the pattern of the shim (for example, a slot coater nozzle manufactured by Suntool Co., Ltd.), or a nozzle device capable of pressurizing molten moisture-curing polyurethane hot melt resin 1 into a gun module and ejecting it in a linear form (for example, a SureBead manufactured by Nordson Corporation).

[0199] Even with the modified coating method (FIG. 5) using the nozzle device 10 described above, the polyurethane hot melt resin 1 applied to the substrate 2 in the application step is wetted and spread (leveled) by the heat in the heating step. This allows the polyurethane hot melt resin 1 to be evenly coated on the substrate 2. Furthermore, by carrying out the heating step, voids and bubbles that have occurred in the polyurethane hot melt resin 1 can be reduced.

[0200] In the above-mentioned application process, in order to apply the polyurethane hot-melt resin 1 uniformly and without voids onto the substrate 2, it is preferable to melt the polyurethane hot-melt resin 1 by heating it to a temperature of 100°C or higher and 140°C or lower, and then discharge the polyurethane hot-melt resin 1 from the resin nozzle hole 9 of the nozzle device 10 in a state in which the viscosity of the polyurethane hot-melt resin 1 is 1000 mPa.s or higher and 5000 mPa.s or lower.

[0201] Furthermore, the above-mentioned "heating the polyurethane hot-melt resin 1 to a temperature of 100°C or higher and 140°C or lower" can be achieved, for example, by heating the polyurethane hot-melt resin 1 supplied to the nozzle device 10 with a heater built into the application head of the nozzle device 10. Alternatively, the polyurethane hot-melt resin 1 may be heated to a temperature of 100°C or higher and 140°C or lower by a heater provided outside the nozzle device 10 and melted, and then supplied to the nozzle device 10 and ejected from the nozzle device 10.

[0202] In the coating methods of the above-described embodiments and modifications (FIGS. 2 and 5), the polyurethane hot-melt resin 1 applied to the substrate 2 may be heated in the heating step by irradiating the polyurethane hot-melt resin 1 with infrared rays from a heat source (infrared irradiation device). Alternatively, the polyurethane hot-melt resin 1 may be heated in the heating step by placing the substrate 2 on which the polyurethane hot-melt resin 1 has been applied in a heating furnace. In either case, the polyurethane hot-melt resin 1 can be uniformly coated on the substrate 2, and voids and bubbles that may have occurred in the polyurethane hot-melt resin 1 can be reduced.

[0203] Furthermore, in the coating methods of the above-described embodiments and modified examples (FIGS. 2 and 5), a printed circuit board supporting an electrical component 3 (e.g., an integrated circuit) is used as the substrate 2, but the substrate to be coated with polyurethane hot melt resin in the coating method of the present invention is not limited to the above-described printed circuit board, and various substrates may be used.

[0204] The inventors of the present invention conducted a test to confirm the effects of the present invention, which will be described below.

[0205] This test compared the uniformity of the polyurethane hot-melt resin 1 coated on the substrate 2 for Examples 1 to 10, which performed both the coating and heating steps described above, and Comparative Examples 1 to 3, which performed only the coating step described above. In Examples 1 and 2, AMR-10 manufactured by Sanyu Rec Co., Ltd. was used as the polyurethane hot-melt resin 1. In Example 3, AMR-06 manufactured by Sanyu Rec Co., Ltd. was used as the polyurethane hot-melt resin 1. In Examples 4 to 10 and Comparative Examples 1 to 3, AMR-09 manufactured by Sanyu Rec Co., Ltd. was used as the polyurethane hot-melt resin 1. FIG. 6 shows the relationship between viscosity and temperature during heating and cooling of the polyurethane hot-melt resin 1 (AMR-10) used in Examples 1 and 2. In this test, the uniformity of the polyurethane hot-melt resin 1 coated on the substrate 2 was evaluated visually.

[0206] Table 2 below shows the application and heating process conditions, as well as the average coating amount per unit area, maximum thickness, and evaluation of uniformity of the coating for Examples 1 to 10. Table 3 below shows the application process conditions, as well as the average coating amount per unit area, maximum thickness, and evaluation of uniformity of the coating for Comparative Examples 1 to 3.

[0207] [Table 2]

[0208] [Table 3]

[0209] In Tables 2 and 3 above, the "type" of "nozzle device" indicates the "type of nozzle device used in the application process," the "temperature of application head" of the "nozzle device" indicates the "temperature of the heater installed in the application head of the nozzle device used in the application process," the "temperature of air 7" of the "nozzle device" indicates the "temperature of air 7 blown onto polyurethane hot melt resin 1 in the application process," the "melting temperature" of "polyurethane hot melt resin 1" indicates the "temperature of polyurethane hot melt resin 1 in a molten state extruded from the nozzle device in the application process," and the "melting viscosity" of "polyurethane hot melt resin 1" indicates the "viscosity of polyurethane hot melt resin 1 in a molten state extruded from the nozzle device in the application process (i.e., the viscosity of polyurethane hot melt resin 1 at the temperature shown in "melting temperature")."

[0210] In addition, in this test, in the heating process of Examples 1 to 10, the polyurethane hot-melt resin 1 was heated by placing the substrate 2 on which the polyurethane hot-melt resin 1 was applied in a heating furnace and heating it.In Table 2 above, the ``heating temperature'' under ``heat source'' indicates the ``temperature at which the polyurethane hot-melt resin 1 was heated (temperature inside the heating furnace),'' and the ``heating time'' under ``heat source'' indicates the ``time at which the polyurethane hot-melt resin 1 was heated (time the substrate 2 was placed in the heating furnace).''

[0211] In addition, in Tables 2 and 3 above, the "average coating amount per unit area" of "Coating" is "the average coating amount per unit area of ​​polyurethane hot melt resin 1 coated on substrate 2 (mg / cm 2 )" and the average application amount (mg / cm 2 ) is an index proportional to the average thickness of the layer of polyurethane hot melt resin 1 coated on substrate 2. In Tables 2 and 3 above, the "maximum thickness" of "coating" indicates the "maximum thickness of polyurethane hot melt resin 1 coated on substrate 2."

[0212] Furthermore, Tables 2 and 3 above show the "coating evaluation results" for the "uniformity" of the "coating." Examples that were evaluated as having a uniform coating without voids or bubbles are given an A, examples that were evaluated as having small voids but still usable are given a B, and examples that were evaluated as having voids and uncoated areas are given a C.

[0213] In Examples 1 to 10, in which a heating step was performed, the uniformity evaluation was all A. In contrast, in Comparative Examples 1 to 3, in which a heating step was not performed, the uniformity evaluation was B or C. This confirmed that performing a heating step is effective in realizing a uniform coating without voids or bubbles.

[0214] In Examples 1 to 10 in which the heating step was performed, the average coating amount per unit area of ​​the polyurethane hot-melt resin 1 coated on the substrate 2 was 8 mg / cm 2 More than 25mg / cm 2 This confirmed that performing a heating process is effective in achieving a thin coating.

[0215] In addition, in Examples 1 to 10, the coating surface was flat and the maximum coating thickness was kept within the range of 0.08 mm or more and 0.25 mm or less. In Comparative Example 3, the coating swelled significantly, resulting in a maximum thickness of a large value of 2 mm (Figure 7 is an image showing the state in which polyurethane hot-melt resin 1 (AMR-09) is coated on substrate 2 in Example 4, Figure 8 is an image showing the state in which polyurethane hot-melt resin 1 (AMR-09) is coated on substrate 2 in Comparative Example 1, and Figure 9 is an image showing the state in which polyurethane hot-melt resin 1 (AMR-09) is coated on substrate 2 in Comparative Example 3). [Explanation of symbols]

[0216] 1. Polyurethane hot melt resin 2 boards 4,10 Nozzle device 5,9 Resin nozzle hole 6 Air nozzle holes 7. Air 8. Hot Air

Claims

1. a coating step of coating a molten moisture-curable polyurethane hot-melt resin onto a substrate by discharging the polyurethane hot-melt resin from a nozzle device onto the substrate; a heating step of heating the polyurethane hot-melt resin applied to the substrate.

2. 2. The coating method according to claim 1, wherein the application step uses a nozzle device that blows air discharged from an air nozzle hole onto the molten moisture-curing polyurethane hot-melt resin discharged from a resin nozzle hole, thereby causing the polyurethane hot-melt resin discharged from the nozzle device to be applied onto the substrate in the form of particles.

3. 2. The coating method according to claim 1, wherein the coating step uses a nozzle device that discharges the molten moisture-curing polyurethane hot-melt resin in a linear shape from a resin nozzle hole, so that the polyurethane hot-melt resin discharged from the nozzle device is applied in a linear shape onto the substrate.

4. 2. The coating method according to claim 1, wherein in the applying step, the polyurethane hot-melt resin is melted by heating it to a temperature of 100° C. or higher and 140° C. or lower, and the polyurethane hot-melt resin is discharged from the nozzle device in a state where the viscosity of the polyurethane hot-melt resin is 1,000 mPa.s or higher and 5,000 mPa.s or lower.

5. 2. The coating method according to claim 1, wherein the heating step heats the polyurethane hot-melt resin applied to the substrate by blowing hot air onto the polyurethane hot-melt resin.

6. 2. The coating method according to claim 1, wherein in the heating step, the polyurethane hot-melt resin applied to the substrate is heated by irradiating the polyurethane hot-melt resin with infrared rays.

7. The coating method according to claim 1 , wherein in the heating step, the substrate coated with the polyurethane hot-melt resin is placed in a heating furnace and heated, thereby heating the polyurethane hot-melt resin.

8. 2. The coating method according to claim 1, wherein the number average molecular weight (Mn) of the polyurethane hot-melt resin is 2,000 or more and 15,000 or less.

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