Adhesives, cured products and laminates

Abstract

To provide an adhesive for a structure which has high flexibility and coating film strength, is excellent in heat resistance, adhesion and coating property, and is suitable for fields of automobiles, building materials, vessels, and aircrafts.SOLUTION: An adhesive contains an urethane-modified resin (C), aromatic polyisocyanate (D), and polyether polyol (A2), wherein the urethane-modified resin (C) is a reaction product of an isocyanato group of an urethane prepolymer having an isocyanate group at its terminal with an amino group of a monoamine compound having a molecular weight of less than 200, the urethane prepolymer is a reaction product of polyol (A) containing polyether polyol (A1) with polyisocyanate (B), the polyether polyol (A1) has a structural unit derived from amorphous polyether polyol (E) and a structural unit derived from crystalline polyether polyol (F), the monoamine compound having the molecular weight of less than 200 has a hydroxyl group or a sulfanyl group and an amino group in the molecule, and a percentage content of the polyether polyol (A2) is within a range of 25-250 mass% based on the total mass of the urethane-modified resin (C).SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an adhesive that has high flexibility in low temperature regions and is excellent in coating strength, heat resistance, and adhesiveness. [Background technology]

[0002] In fields such as automobiles, building materials, ships, and aircraft, various structural adhesives are used to bond and fix metals such as iron, aluminum, and stainless steel, as well as resins, glass, and ceramics. In recent years, weight reduction has been promoted in the automobile and aircraft fields to improve fuel efficiency, and there has been an active movement to increase the use of materials made from plastics and fiber-reinforced plastics (hereinafter referred to as FRP) and to replace iron with lighter aluminum, creating a demand for adhesives that can firmly bond these materials. Furthermore, from the perspectives of workability and reducing environmental impact, there is a demand for adhesives that do not contain volatile organic compounds.

[0003] However, for example, when bonding a metal such as aluminum to a material with a different linear expansion coefficient such as FRP, there is a problem that the difference in expansion coefficient between the materials caused by temperature changes during the manufacturing process or in the operating temperature environment places high stress on the adhesive layer, accelerating the destruction or deterioration of the adhesive layer.

[0004] To address these issues, for example, Patent Documents 1 to 3 disclose methods of adding long-chain polyamines or nano-dispersed rubber particles to epoxy compounds that have high adhesive properties to metals and FRP for the purpose of stress relief. However, although these methods can impart a certain degree of flexibility, the resulting adhesive layer remains hard and brittle, and the effect is insufficient.

[0005] On the other hand, Patent Documents 4 to 6 disclose adhesive compositions that have flexibility and coating film strength by using a base agent containing a urethane polymer prepared using a crystalline polyol and a curing agent containing a non-crystalline polyol compound and a polyamine compound.

[0006] However, these methods have problems such as the rapid reactivity between the polyamine compound and the curing agent, which can cause discharge defects due to an increase in viscosity during mixing, and the inability to bond large areas.Furthermore, trace amounts of amino groups remain in the cured film, which can result in insufficient heat resistance. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Special Publication No. 2018-506635 [Patent Document 2] International Publication No. 2007 / 025007 [Patent Document 3] Japanese Patent Application Laid-Open No. 2015-182248 [Patent Document 4] Japanese Patent Application Publication No. 2020-055921 [Patent Document 5] Japanese Patent Publication No. 2020-055922 [Patent Document 6] Japanese Patent Publication No. 2020-055923 Summary of the Invention [Problem to be solved by the invention]

[0008] An object of the present invention is to provide a structural adhesive that has high flexibility and coating strength, and is excellent in heat resistance, adhesion, and coatability, and is suitable for use in fields such as automobiles, building materials, ships, and aircraft. [Means for solving the problem]

[0009] As a result of extensive research conducted by the present inventors to solve the above problems, the present inventors have discovered the following: The present inventors have found that the problems of the present invention can be solved, and have completed the present invention. [1] An adhesive comprising a urethane-modified resin (C), an aromatic polyisocyanate (D), and a polyether polyol (A2), wherein the urethane-modified resin (C) is a reaction product of a urethane prepolymer having an isocyanato group at a terminal and a monoamine compound having a molecular weight of less than 200, the urethane prepolymer is a reaction product of a polyol (A) containing a polyether polyol (A1) and a polyisocyanate (B), the polyether polyol (A1) has structural units derived from a non-crystalline polyether polyol (E) and structural units derived from a crystalline polyether polyol (F), the monoamine compound having a molecular weight of less than 200 has a hydroxyl group or a sulfanyl group in its molecule, and the content of the polyether polyol (A2) is in the range of 25 to 250 mass% based on the total mass of the urethane-modified resin (C). [2] The adhesive according to [1], which contains 30 to 65 mass% of the amorphous polyether polyol (E) and 35 to 70 mass% of the crystalline polyether polyol (F) based on the total mass of the polyol (A). [3] The adhesive according to [1] or [2], wherein the amorphous polyether polyol (E) contains polypropylene glycol. [4] The crystalline polyether polyol (F) is polytetramethylene ether The adhesive according to any one of [1] to [3], which contains glycol. [5] The adhesive according to any one of [1] to [4], wherein the polyether polyol (A2) has a number average molecular weight of less than 750. [6] A cured product of the adhesive described in any one of [1] to [5]. [7] A laminate having a layer made of the cured product according to [6] on a substrate. [Effects of the Invention]

[0010] The present invention can provide a structural adhesive that has high flexibility and coating film strength, and is excellent in heat resistance, adhesiveness, and coatability. DETAILED DESCRIPTION OF THE INVENTION

[0011] The present invention will be described in detail below. Needless to say, other embodiments are also included within the scope of the present invention as long as they are consistent with the spirit of the present invention. Furthermore, in this specification, a numerical range specified using "to" includes the numerical values ​​before and after "to" as the lower and upper limit values ​​of the range. Furthermore, unless otherwise noted, each of the various components appearing in this specification may be used independently, either singly or in combination of two or more.

[0012] <Adhesive> The adhesive of the present invention contains a urethane-modified resin (C), a polyisocyanate (D), and a polyether polyol (A2), the urethane-modified resin (C) is a reaction product of an isocyanato group of a urethane prepolymer having an isocyanato group at a terminal thereof and an amino group of a monoamine compound having a molecular weight of less than 200; the urethane prepolymer is a reaction product of a polyol (A) containing a polyether polyol (A1) and an aromatic polyisocyanate (B), the polyether polyol (A1) has a structural unit derived from a non-crystalline polyether polyol (E) and a structural unit derived from a crystalline polyether polyol (F), the monoamine compound having a molecular weight of less than 200 has a hydroxyl group or a sulfanyl group and an amino group in the molecule, The content of the polyether polyol (A2) is in the range of 25 to 250 mass % based on the total mass of the urethane-modified resin (C). In this way, by combining an amorphous polyether, a urethane-modified resin (C) in which a urea bond formed by the reaction of an isocyanato group with an amino group and a hydroxyl group or a sulfanyl group are introduced adjacent to the terminal region of a urethane resin having a crystalline polyether structure, an aromatic polyisocyanate (B), and a polyether polyol (A2), the flexible urethane moiety is firmly incorporated into the crosslinked structure consisting of the polyether polyol and the aromatic polyisocyanate, thereby exhibiting excellent extensibility derived from the urethane moiety and excellent strength derived from the crosslinked structure. As a result, the adhesive of the present invention has high flexibility and coating film strength, and can exhibit excellent heat resistance, adhesion, and coatability. Therefore, the adhesive of the present invention is suitable for use in fields such as automobiles, building materials, ships, aircraft, etc. Furthermore, the adhesive of the present invention can be used as a liquid, solvent-free adhesive, which is excellent from the standpoints of safety and environmental friendliness.

[0013] <Urethane-modified resin (C)> The urethane-modified resin (C) of the present invention may have a structure obtained by reacting an isocyanato group of a urethane prepolymer having an isocyanato group at its terminal, which is obtained from a polyol (A) containing a polyether polyol (A1) and a polyisocyanate, with an amino group of a monoamine compound having a molecular weight of less than 200 and having a hydroxyl group or a sulfanyl group and an amino group in the molecule. The method for producing the urethane-modified resin (C) is not limited, but it can be preferably produced by the following method. First, a polyol (A) containing a polyether polyol (A1) and a polyisocyanate are reacted to form a urethane prepolymer having isocyanato groups at both ends (hereinafter, step 1). Next, a monoamine compound having a molecular weight of less than 200 and containing a hydroxyl group or a sulfanyl group in the molecule, and a polyether polyol (A2) are added, and the isocyanato groups of the urethane prepolymer react with the amino groups of the monoamine compound to synthesize a urethane-modified resin (C) having hydroxyl groups or sulfanyl groups at both ends of the urethane prepolymer (hereinafter, step 2). All of these reactions may be carried out with or without a solvent. Furthermore, adding polyether polyol (A2) in step 2 is preferred because it allows the reaction to proceed in the absence of a solvent. However, if a solvent is used, it is preferable to remove the solvent under reduced pressure or normal pressure during or after the reaction. In this way, a solvent-free adhesive can be obtained.

[0014] The mass average molecular weight of the urethane-modified resin (C) is not particularly limited, and is preferably 5,000 to 300,000, and more preferably 7,500 to 100,000. When it is 5,000 or more, excellent adhesive strength is obtained, and when it is 300,000 or less, viscosity adjustment is easy.

[0015] <Polyol (A)> The polyol is a compound having two or more hydroxyl groups in the molecule, and examples thereof include polyether polyol, polyester polyol, polycarbonate polyol, polyolefin polyol, plant-derived polyol, etc. The polyol (A) of the present invention includes a polyether polyol (A1).

[0016] (Polyether polyol (A1)) The polyether polyol (A1) contains structural units derived from the amorphous polyether polyol (E) and structural units derived from the crystalline polyether polyol (F). The number average molecular weights of the polyether polyols (E) and (F) are preferably 500 to less than 5,000, more preferably 500 to 3,000. Within this range, excellent flexibility is achieved. In this specification, "crystalline" means being solid at -20°C, and "non-crystalline" means being liquid at -20°C.

[0017] [Amorphous polyether polyol (E)] The amorphous polyether polyol (E) may be any polyether polyol having the above-mentioned "amorphous property," and examples thereof include polymers or copolymers of methylene oxide, ethylene oxide, propylene oxide, butylene oxide, tetrahydrofuran, etc., glycols such as polyethylene glycol, polypropylene glycol, and poly(ethylene / propylene) glycol; Examples include polyols obtained by adding an alkylene oxide such as methylene oxide, ethylene oxide, propylene oxide, butylene oxide, tetrahydrofuran, or polyoxytetramethylene oxide to a compound having two or more active hydrogen groups.

[0018] Examples of the compound having two or more active hydrogen groups include low molecular weight polyols, aliphatic amine compounds, aromatic amine compounds, alkanolamines, and bisphenols.

[0019] Examples of the low molecular weight polyol include bifunctional low molecular weight polyols and trifunctional or higher functional low molecular weight polyols.

[0020] The bifunctional low molecular weight polyol is not particularly limited, and examples thereof include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol, pentanediol, hexanediol, octanediol, nonanediol, dipropylene glycol, diethylene glycol, triethylene glycol, 3-methyl-1,5-pentanediol, 2-butyl-2-ethyl-1,3-propanediol, 2-ethyl-1,3-hexanediol, and 2-methyl-1,8-octane. Examples of the alkyl acrylate copolymer include diol, polyoxyethylene glycol (10 or less moles added), polyoxypropylene glycol (10 or less moles added), cyclohexanediol, cyclohexanedimethanol, tricyclodecane dimethanol, cyclopentadiene dimethanol, dimer diol, bisphenol A, N,N-bis(2-hydroxypropyl)aniline, dimethylolacetic acid, dimethylolpropionic acid, dimethylolbutanoic acid, 2,2-dimethylolbutyric acid, 2,2-dimethylolpentanoic acid, dihydroxysuccinic acid, dihydroxypropionic acid, and dihydroxybenzoic acid.

[0021] The tri- or higher functional low molecular weight polyol is not particularly limited, and examples thereof include trimethylolethane, trimethylolpropane, 1,1,1-trimethylolbutane, 1,2,3-butanetriol, 1,2,4-butanetriol, 1,2,6-butanetriol, trimethylolbutene, trimethylolpentene, trimethylolhexene, trimethylolheptene, trimethyloloctene, trimethylolnonene, trimethyloldecene, trimethylolundecene, trimethyloldodecene, and trimethyloltridecene. , trimethylolpentadecene, trimethylolhexadecene, trimetrolheptadecene, trimethyloloctadecene, 1,1,1-trimethylol-2-methyl-hexane, 1,1,1-trimethylol-3-methyl-hexane, 1,1,1-trimethylol-2-ethyl-hexane, 1,1,1-trimethylol-3-ethyl-hexane, trimethylolhexene, 1,2,3-octanetriol, 1,3,7-octanetriol, 3,7-dimethyl-1,2,3-octanetriol, 1,1,1-, 1, 1,1-trimethyloldecane, 1,2,10-decanetriol, 1,1,1-trimethylolisoheptadecane, 1,1,1-trimethylol-sec-butane, 1,1,1-trimethylol-tert-pentane, 1,1,1-trimethylol-tert-nonane, 1,1,1-trimethylol-tert-tridecane, 1,1,1-trimethylol-tert-heptadecane, 1,1,1-trimethylol-2-methyl-hexane, 1,1,1-trimethylol-3-methyl-hexane, 1,1,1-trimethylol 1,1,1-trimethylol-2-ethyl-hexane, 1,1,1-trimethylol-3-ethyl-hexane, 1,1,1-trimethylolisoheptadecane, 1,2,3,4-butanetetraol, pentaerythritol, dipentaerythritol, tripentaerythritol, glycerin, diglycerin, triglycerin, polyglycerin, ditrimethylolethane, ditrimethylolpropane, tris(2-hydroxyethyl)isocyanurate, benzene-1,3,5-triol, benzene-1,2,3-triol, stilbene-3,Examples of sugars include 4',5-triol, sucrose, inositol, sorbitan, sorbitol, mannitol, sucrose, cellulose, and xylitol.

[0022] Examples of aliphatic amine compounds include ethylenediamine, triethylenetetramine, diethylenetriamine, and triaminopropane. Examples of aromatic amine compounds include toluenediamine and diphenylmethane-4,4-diamine. Examples of alkanolamines include ethanolamine and diethanolamine. Examples of bisphenols include bisphenol A, bisphenol AP, bisphenol B, bisphenol C, bisphenol E, and bisphenol F.

[0023] The amorphous polyether polyol (E) preferably contains polypropylene glycol, which has particularly excellent flexibility.

[0024] [Crystalline polyether polyol (F)] The crystalline polyether polyol (F) may be any polyether polyol having the above-mentioned "crystallinity," and examples thereof include polyethylene glycol and polytetramethylene ether glycol.

[0025] The crystalline polyether polyol (F) preferably contains polytetramethylene ether glycol, which has high cohesive strength and can exhibit excellent coating strength, heat resistance, and adhesion while maintaining the flexibility of the urethane moiety.

[0026] The composition preferably contains 30 to 65 mass% of the amorphous polyether polyol (E) and 35 to 70 mass% of the crystalline polyether polyol (F) based on the total mass of the polyol (A), and more preferably contains 35 to 60 mass% of the amorphous polyether polyol (E) and 40 to 65 mass% of the crystalline polyether polyol (F). By using such a blending ratio, a tough cured film can be obtained, which has excellent flexibility, heat resistance, and adhesiveness.

[0027] (Other polyols) The polyol (A) constituting the urethane-modified resin (C) may contain other polyols other than the polyether polyol (A1), such as polyester polyols, polycarbonate polyols, polyolefin polyols, and plant-derived polyols, for the purpose of adjusting the urethane bond concentration or introducing various functional groups, within a range that does not impair the effects of the present invention.

[0028] (polyester polyol) Examples of polyester polyols include polyester polyols obtained by condensation reaction of the above-mentioned low molecular weight polyols with dibasic acid components, and lactone-based polyester polyols obtained by ring-opening polymerization of cyclic ester compounds such as lactones. Examples of the dibasic acid component include aliphatic or aromatic dibasic acids such as terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, adipic acid, azelaic acid, dimer acid, succinic acid, hydrogenated dimer acid, phthalic anhydride, maleic anhydride, itaconic anhydride, trimellitic acid, glutaric acid, pimelic acid, suberic acid, and sebacic acid, and anhydrides thereof.

[0029] Examples of lactones include ε-caprolactone, poly(β-methyl-γ-valerolactone), and polyvalerolactone.

[0030] (Polycarbonate polyol) Examples of polycarbonate polyols include reaction products of the above-mentioned low molecular weight polyols with carbonate compounds such as dialkyl carbonates, alkylene carbonates, and diaryl carbonates.

[0031] Examples of dialkyl carbonates include dimethyl carbonate and diethyl carbonate. Examples of alkylene carbonates include ethylene carbonate. Examples of diaryl carbonates include diphenyl carbonate.

[0032] (Polyolefin polyol) Examples of polyolefin polyols include hydroxyl group-containing polybutadiene, hydrogenated hydroxyl group-containing polybutadiene, hydroxyl group-containing polyisoprene, hydrogenated hydroxyl group-containing polyisoprene, hydroxyl group-containing chlorinated polypropylene, and hydroxyl group-containing chlorinated polyethylene.

[0033] (Vegetable oil-based polyol) Examples of vegetable oil-based polyols include polyols made from plant-derived castor oil, dimer acid, or soybean oil.

[0034] The number average molecular weight of the polyester polyol, polycarbonate polyol, polyolefin polyol, and vegetable oil polyol is preferably 500 or more and 5,000 or less, and more preferably 700 or more and 3,500 or less. A number average molecular weight of 500 to 5,000 is preferred because the resulting cured film has better adhesive strength and flexibility.

[0035] <Polyisocyanate (B)> Examples of the polyisocyanate (B) constituting the urethane prepolymer include aromatic, aliphatic, and alicyclic diisocyanates.

[0036] Examples of aromatic diisocyanates include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, m-phenylene diisocyanate, p-phenylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,4-diphenylmethane diisocyanate, 2,2'-diphenylmethane diisocyanate, 1,5-naphthalene diisocyanate, tolidine diisocyanate, xylylene diisocyanate, m-tetramethylxylene diisocyanate, p-tetramethylxylene diisocyanate, 3,3'-dimethyl-4,4'-biphenylene diisocyanate, 3,3'-dimethoxy-4,4'-biphenylene diisocyanate, 3,3'-dichloro-4,4'-biphenylene diisocyanate, and 1,5-tetrahydronaphthalene diisocyanate.

[0037] Examples of aliphatic diisocyanates include trimethylene diisocyanate, tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, 1,2-propylene diisocyanate, 2,3-butylene diisocyanate, 1,3-butylene diisocyanate, dodecamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, lysine diisocyanate, lysine ester triisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate tetramethylene diisocyanate, pentamethylene diisocyanate, and trimethylhexamethylene diisocyanate.

[0038] Examples of alicyclic diisocyanates include isophorone diisocyanate, 1,3-cyclopentane diisocyanate, 1,3-cyclohexane diisocyanate, 1,4-cyclohexane diisocyanate, methyl-2,4-cyclohexane diisocyanate, methyl-2,6-cyclohexane diisocyanate, 4,4'-methylenebis(cyclohexyl isocyanate), 1,4-bis(isocyanatomethyl)cyclohexane, hydrogenated xylylene diisocyanate, dimer acid diisocyanate, and norbornene diisocyanate.

[0039] <Urethane prepolymer> The urethane prepolymer is a reaction product of a polyol (A) and a polyisocyanate (B).

[0040] The reaction between the polyol (A) and the polyisocyanate (B) can be carried out using a known urethane reaction, preferably in the absence of a solvent. By using an excess of polyisocyanate, a urethane prepolymer having isocyanato groups at both ends can be obtained. The molar ratio of isocyanato groups to hydroxyl groups during the reaction (moles of isocyanato groups / moles of hydroxyl groups) is preferably 1.05 to 2.00, more preferably 1.10 to 1.50. In the urethane reaction, a catalyst may be used to adjust the reactivity.

[0041] Known metal catalysts, amine catalysts, etc. can be used as the catalyst. Examples of metal catalysts include dibutyltin dilaurate, tin octoate, dibutyltin di(2-ethylhexoate), lead 2-ethylhexoate, 2-ethylhexyl titanate, titanium ethyl acetate, iron 2-ethylhexoate, cobalt 2-ethylhexoate, zinc naphthenate, cobalt naphthenate, and tetra-n-butyltin. Examples of amine catalysts include tertiary amines such as tetramethylbutanediamine. The amount of catalyst used is preferably in the range of 0.05 to 1 mol% based on the total mass of the polyol.

[0042] The number average molecular weight of the urethane prepolymer is not particularly limited, but is preferably in the range of 3,000 to 200,000. If it is 3,000 or more, the adhesive strength is excellent, and if it is 200,000 or less, the viscosity can be easily adjusted.

[0043] <Monoamine compounds with a molecular weight of less than 200 and containing a hydroxyl group or a sulfanyl group in the molecule> By reacting the urethane prepolymer obtained above with a monoamine compound having a molecular weight of less than 200 and having a hydroxyl group or a sulfanyl group in the molecule, preferably in the presence of a polyether polyol (A2), a mixture of a urethane-modified resin (C) having a urea bond and a hydroxyl group or a sulfanyl group in close proximity at both terminal regions of the urethane resin and the polyether polyol (A2) can be obtained. When the molecular weight of the monoamine compound is less than 200, the urea bond and the hydroxyl group or sulfanyl group are in close proximity, and further, the hydroxyl group or sulfanyl group crosslinks via the aromatic polyisocyanate (B), forming a tough cured film and imparting excellent coating film strength, flexibility, heat resistance, and adhesion. The molecular weight of the monoamine compound is preferably in the range of 50 to 150. When the molecular weight of the monoamine compound is 200 or more, the effect of the urea bond and the hydroxyl group or sulfanyl group being in close proximity cannot be obtained, and a tough cured film cannot be formed.

[0044] The amino group of the monoamine compound used in the present invention is more reactive than a hydroxyl group or a sulfanyl group, and therefore preferentially reacts with the isocyanato group at the end of the urethane prepolymer to form a urea bond, thereby efficiently introducing a hydroxyl group or a sulfanyl group into the end of the urethane prepolymer. From the viewpoint of reactivity with the isocyanato group, the monoamine compound is preferably a primary or secondary amine, and more preferably a primary amine. The polyether polyol (A2) described below also has hydroxyl groups and may react with the isocyanato groups of the urethane prepolymer. However, because the amino groups of the monoamine compound are more reactive than the hydroxyl groups, the reaction between the polyether polyol (A2) and the isocyanato groups of the urethane prepolymer is suppressed.

[0045] The monoamine compound having a molecular weight of less than 200 and having a hydroxyl group or a sulfanyl group in the molecule may be either a monoamine compound having a molecular weight of less than 200 and having a hydroxyl group in the molecule, or a monoamine compound having a molecular weight of less than 200 and having a sulfanyl group in the molecule.

[0046] Examples of monoamine compounds having a molecular weight of less than 200 and containing a hydroxyl group in the molecule include 2-aminoethanol, 2-amino-2-methyl-1-propanol, 2-(methylamino)ethanol, 2-(ethylamino)ethanol, 2-(butylamino)ethanol, and diethanolamine, with 2-aminoethanol being preferred.

[0047] Examples of monoamine compounds having a molecular weight of less than 200 and containing a sulfanyl group in the molecule include 2-aminoethanethiol, 3-aminopropyl-1-thiol, 1-aminopropyl-2-thiol, and 4-amino-1-butanethiol, with 2-aminoethanethiol being preferred.

[0048] <Polyether polyol (A2)> The adhesive of the present invention contains the polyether polyol (A2) in a range of 25 to 250 mass % based on the total mass of the urethane-modified resin (C). By setting the content within this range, a strong crosslinked structure is formed, and excellent coating strength, flexibility, and heat resistance can be obtained. The content of the polyether polyol (A2) is preferably 30 to 225 mass %, more preferably 35 to 200 mass %.

[0049] Examples of the polyether polyol (A2) include polymers or copolymers of methylene oxide, ethylene oxide, propylene oxide, butylene oxide, tetrahydrofuran, etc., glycols such as polyethylene glycol, polypropylene glycol, and poly(ethylene / propylene) glycol; Examples of the polyether polyol include polyols obtained by adding an alkylene oxide such as methylene oxide, ethylene oxide, propylene oxide, butylene oxide, tetrahydrofuran, or polyoxytetramethylene oxide to a compound having two or more active hydrogen groups. In the present invention, the polyether polyol (A1) and the polyether polyol (A2) may be the same or different. As described above, the reaction product of step 2 is mainly composed of a reaction product of a urethane prepolymer and a monoamine compound having a molecular weight of less than 200 and containing a hydroxyl group or a sulfanyl group in the molecule, and it is preferred that the majority of the polyether polyol (A2) remains unreacted.

[0050] The number average molecular weight of the polyether polyol (A2) is preferably less than 750. When the number average molecular weight is less than 750, the coating film strength, flexibility, and heat resistance are excellent, which is preferable.

[0051] <Solvent> Reactions for producing urethane-modified resins, such as the reaction between a polyol and a polyisocyanate, and the reaction between a urethane prepolymer and a monoamine compound having a molecular weight of less than 200 and a hydroxyl group or a sulfanyl group in the molecule, may be carried out in a solvent. The solvent that may be used in the reaction of polyol with polyisocyanate is not particularly limited as long as it does not react with an isocyanato group, and examples thereof include acetone, methyl ethyl ketone, cyclohexanone, methyl acetate, ethyl acetate, propyl acetate, toluene, xylene, anisole, propylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, N-vinylpyrrolidone, N-methylcaprolactam, dimethyl sulfoxide, tetramethylurea, pyridine, dimethyl sulfone, hexamethyl sulfoxide, m-cresol, γ-butyrolactone, and γ-valerolactone. In addition to the above-mentioned solvents, alcohols such as ethanol, isopropanol, tertiary butanol, and diacetone alcohol can be used as solvents for the reaction of the urethane prepolymer with a monoamine compound having a molecular weight of less than 200 and having a hydroxyl group or a sulfanyl group in the molecule.

[0052] <Aromatic polyisocyanate (D)> The adhesive of the present invention contains an aromatic polyisocyanate (D) as a crosslinking agent in addition to the urethane-modified resin (C) and the polyether polyol (A2). The aromatic polyisocyanate (D) in the present invention may be any compound having two or more aromatic isocyanate groups in the molecule, and examples thereof include the above-mentioned aromatic diisocyanates, polyisocyanate-modified products, and other condensates.

[0053] Examples of polyisocyanate-modified products include allophanate products, nurate products, biuret products, adduct products, and carbodiimide-modified products, as well as isocyanato group-terminated urethane resins obtained by reacting polyisocyanate with polyol and / or polyamine under conditions of excess isocyanato groups.

[0054] An example of the nurate compound is a nurate compound of tolylene diisocyanate (product name: Coronate 2030, manufactured by Nippon Polyurethane Co., Ltd.).

[0055] Examples of the adduct include a trimethylolpropane adduct of tolylene diisocyanate (product name "Takenate D-103H", manufactured by Mitsui Chemicals, Inc.) and a trimethylolpropane adduct of diphenylmethane diisocyanate.

[0056] An example of the carbodiimide-modified product is carbodiimide-modified diphenylmethane diisocyanate (product name "Isonate 143L", manufactured by Dow).

[0057] The polyisocyanate that forms the isocyanato group-terminated urethane resin may be any of the polyisocyanates described above, and the polyol that forms the isocyanato group-terminated urethane resin may be any of the polyols described above.

[0058] Examples of polyamines that form the isocyanato group-terminated urethane resin include ethylenediamine, triethylenetetramine, diethylenetriamine, triaminopropane, toluenediamine, diphenylmethane-4,4-diamine, isophoronediamine, ethanolamine, and diethanolamine.

[0059] Other condensates include polyfunctional products of the above polyisocyanates, such as polymethylene polyphenyl polyisocyanate (product name "PAPI27", manufactured by Dow).

[0060] Among these, the combined use of tolylene diisocyanate or diphenylmethane diisocyanate and a modified polyisocyanate made of tolylene diisocyanate or diphenylmethane diisocyanate is preferred because high coating strength can be obtained.

[0061] The molar ratio of isocyanato groups to total hydroxyl groups contained in the adhesive (number of moles of isocyanato groups / number of moles of hydroxyl groups) is preferably 0.5 to 5.0, more preferably 0.8 to 3.0. A molar ratio of 0.5 to 5.0 is preferred because it results in excellent coating film strength, flexibility, and adhesive strength.

[0062] <Additives> The adhesives of the present invention may further contain known additives such as reaction accelerators, silane coupling agents, phosphoric acid or phosphoric acid derivatives, leveling or defoaming agents, polyamines, fillers, propellants, plasticizers, superplasticizers, wetting agents, flame retardants, viscosity modifiers, preservatives, stabilizers, and colorants.

[0063] Examples of the reaction accelerator include metal catalysts such as dibutyltin diacetate, dibutyltin dilaurate, dioctyltin dilaurate, and dibutyltin dimaleate; tertiary amines such as 1,8-diaza-bicyclo(5,4,0)undecene-7 and 1,5-diazabicyclo(4,3,0)nonene-5,6-dibutylamino-1,8-diazabicyclo(5,4,0)undecene-7; and reactive tertiary amines such as triethanolamine. The amount of the reaction accelerator added is preferably 0.005 to 5% by mass based on the total mass of the polyisocyanate (A).

[0064] Examples of silane coupling agents include trialkoxysilanes having a vinyl group, such as vinyltrimethoxysilane and vinyltriethoxysilane; trialkoxysilanes having an amino group, such as 3-aminopropyltriethoxysilane and N-(2-aminoethyl)3-aminopropyltrimethoxysilane; trialkoxysilanes having a glycidyl group, such as 3-glycidoxypropyltrimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane and 3-glycidoxypropyltriethoxysilane; trialkoxysilanes having an isocyanato group, such as 3-isocyanatepropyltriethoxysilane; and trialkoxysilanes having a mercapto group, such as 3-mercaptopropylmethyldimethoxysilane and 3-mercaptopropyltrimethoxysilane. The amount of the silane coupling agent added is preferably 0.05 to 10% by mass based on the total mass of the polyisocyanate (A).

[0065] Among phosphoric acid and phosphoric acid derivatives, phosphoric acid may be any phosphoric acid having at least one free oxygen acid, such as hypophosphorous acid, phosphorous acid, orthophosphoric acid, and hypophosphoric acid; and condensed phosphoric acids such as metaphosphoric acid, pyrophosphoric acid, tripolyphosphoric acid, polyphosphoric acid, and ultraphosphoric acid. Phosphoric acid derivatives include those obtained by partially esterifying the above-mentioned phosphoric acids with alcohols while leaving at least one free oxygen acid. Examples of these alcohols include aliphatic alcohols such as methanol, ethanol, ethylene glycol, and glycerin; and aromatic alcohols such as phenol, xylenol, hydroquinone, catechol, and phloroglucinol. The amount of phosphoric acid and its derivatives to be added is preferably 0.005 to 5% by mass in total based on the total mass of the polyisocyanate (A).

[0066] Examples of leveling agents include polyether-modified polydimethylsiloxanes, polyester-modified polydimethylsiloxanes, aralkyl-modified polymethylalkylsiloxanes, polyester-modified hydroxyl group-containing polydimethylsiloxanes, polyetherester-modified hydroxyl group-containing polydimethylsiloxanes, acrylic copolymers, methacrylic copolymers, polyether-modified polymethylalkylsiloxanes, acrylic acid alkyl ester copolymers, methacrylic acid alkyl ester copolymers, and lecithin.

[0067] Examples of the antifoaming agent include known antifoaming agents such as silicone resin, silicone solution, copolymers of alkyl vinyl ether, alkyl acrylate ester and alkyl methacrylate ester.

[0068] Examples of polyamines include aromatic polyamines such as metaphenylenediamine, orthophenylenediamine, paraphenylenediamine, m-xylylenediamine, diaminodiphenylmethane, diaminodiphenylsulfone, diaminodiethyldiphenylmethane, diethylmethylbenzenediamine, 2-methyl-4,6-bis(methylthio)-1,3-benzenediamine, 4,4'-methylenebis(2-chloroaniline), 4,4'-methylenebis(3-chloro-2,6-diethylaniline), 4,4'-diamino-3,3'-diethyl-5,5'-dimethyldiphenyl, methane trimethylenebis(4-aminobenzoate), 2,4'-diamino-3,5'-diethyltoluene, 2,6'-diamino-3,5'-diethyltoluene, and bis(4-amino-2,3-dichlorophenyl)methane.

[0069] ≪Laminated body, cured product≫ The cured product of the present invention can be preferably obtained by mixing a composition comprising a urethane-modified resin (C) and a polyether polyol (A2) with an aromatic polyisocyanate (D) by a known method, followed by curing. The laminate of the present invention has a resin layer comprising the cured product on a substrate. The method for producing the laminate is not particularly limited. For example, the adhesive can be applied to one surface of a substrate, and then another substrate can be placed on the uncured adhesive surface, followed by heat treatment at about 20 to 150°C to cure the adhesive, thereby obtaining a laminate. The thickness of the adhesive after curing is preferably 0.1 μm to 300 mm.

[0070] The adhesive of the present invention can be used to bond a wide variety of substrates, whether they are the same or different, including metals such as aluminum, thermoplastic polymers such as polyethylene, polyethylene, polyurethane, polyacrylate, polycarbonate, and copolymers thereof, thermosetting polymers such as vulcanized rubber, urea-formaldehyde foam, melamine resin, wood, carbon fiber reinforced plastic, glass fiber reinforced plastic, and other fiber reinforced plastics.

[0071] The adhesive of the present invention has excellent coating strength, flexibility, heat resistance, and adhesive power, and laminates using the adhesive are useful as structural members (panel parts, frame parts, suspension parts, etc.) for automobiles, building materials, ships, aircraft, and other transportation equipment. [Example]

[0072] The present invention will be described in more detail below with reference to examples, but the following examples are not intended to limit the scope of the invention. Unless otherwise specified, "parts" in the examples represent "parts by mass."

[0073] <Mass average molecular weight (Mw)> The mass-average molecular weight (Mw) of the resin was determined by gel permeation chromatography (GPC) using a GPC-8020 (Tosoh Corporation) GPC system, tetrahydrofuran as the eluent, and three TSKgel SuperHM-M (Tosoh Corporation) columns connected in series at a flow rate of 0.6 ml / min, an injection volume of 10 μl, and a column temperature of 40°C.

[0074] The abbreviations for compounds used in this specification are shown below. <Polyol> P-400: Bifunctional polypropylene glycol, number average molecular weight 400, hydroxyl value 280 mg KOH / g, manufactured by ADEKA Corporation P-700: Bifunctional polypropylene glycol, number average molecular weight 700, hydroxyl value 160 mg KOH / g, manufactured by ADEKA Corporation P-1000: Difunctional polypropylene glycol, number average molecular weight 1,000, hydroxyl value 112 mg KOH / g, manufactured by ADEKA Corporation P-2000: Bifunctional polypropylene glycol, number average molecular weight 2,000, hydroxyl value 56 mg KOH / g, manufactured by ADEKA Corporation PTG-1000: Bifunctional polytetramethylene ether glycol, number average molecular weight 1,000, hydroxyl value 112 mgKOH / g, manufactured by Hodogaya Chemical Co., Ltd. PTG-2000: Bifunctional polytetramethylene ether glycol, number average molecular weight 2,000, hydroxyl value 56 mgKOH / g, manufactured by Hodogaya Chemical Co., Ltd. C-1090: Bifunctional polycarbonate polyol, number average molecular weight 1,000, hydroxyl value 112 mg KOH / g, manufactured by Kuraray Co., Ltd.

[0075] <Polyisocyanate (B)> IPDI: Isophorone diisocyanate TDI: Tolylene diisocyanate

[0076] <Crosslinking agent> MDI: Diphenylmethane diisocyanate TDI-TMP adduct: Trimethylolpropane adduct of tolylene diisocyanate, manufactured by Mitsui Chemicals HDI: Hexamethylene diisocyanate HDI-TMP adduct: Trimethylolpropane adduct of hexamethylene diisocyanate, manufactured by Mitsui Chemicals

[0077] <Production of urethane-modified resin> (Production Example 1) A reaction vessel equipped with a nitrogen gas inlet tube, a stirrer, a thermometer, and a reflux condenser was charged with 40.0 parts of P-1000 as the amorphous polyether polyol (E), 60.0 parts of PTG-2000 as the crystalline polyether polyol (F), 21.7 parts of isophorone diisocyanate as the polyisocyanate, and 0.02 parts of dibutyltin dilaurate as the catalyst, and after uniform stirring, the mixture was reacted at 110°C for 5 hours under a nitrogen atmosphere to obtain a urethane prepolymer. Next, the mixture was cooled to 80°C, and 126.1 parts of P-400 and 4.3 parts of 2-aminoethanethiol were added as polyether polyol (A2), and the mixture was allowed to react at 75°C for 2 hours to obtain a composition (CE-1) consisting of urethane-modified resin (C-1) and polyether polyol. The end point of the reaction was determined by FT-IR, where a peak (2270 cm) derived from the isocyanato group was detected. -1 This was confirmed by the disappearance of the nearby

[0078] (Production Examples 2 to 39, Comparative Production Examples 1 to 10) The same operations as in Production Example 1 were carried out except that the compounds and formulations were changed to those shown in Tables 1 to 3, to obtain compositions (CE-2 to 43) consisting of urethane-modified resins (C-2 to 43) and polyether polyol (A2) in Production Examples 2 to 39 and Comparative Production Examples 7 to 10, and compositions (UE-5 to 6) consisting of urethane resins (U-5 to 6) and polyether polyol (A2), respectively.

[0079] The mass average molecular weights of the obtained urethane-modified resins and urethane resins, the proportion (%) of polyether polyol (A2) based on the total mass of the urethane-modified resin (C), the proportion (%) of amorphous polyether polyol (E) in polyol (A), and the proportion (%) of crystalline polyether polyol (F) in polyol (A) are shown in Tables 1 to 4.

[0080] Table 1 JPEG0007810060000001.jpg21593

[0081] Table 2 JPEG0007810060000002.jpg21693

[0082] Table 3 JPEG0007810060000003.jpg21590

[0083] Table 4 JPEG0007810060000004.jpg239121

[0084] <Preparation of adhesive> [Example 1] The adhesive of Example 1 was prepared by mixing 10.0 parts of the composition (CE-1) consisting of the urethane-modified resin (C-1) and the polyether polyol (A2) obtained in Production Example 1, 2.5 parts of MDI as the aromatic polyisocyanate (D), and 3.0 parts of a TDI-TMP adduct at room temperature.

[0085] [Examples 2 to 41 and Comparative Examples 1 to 12] The adhesives of Examples 2 to 41 and Comparative Examples 1 to 12 were prepared in the same manner as in Example 1, except that the blending compositions were changed as shown in Tables 5 to 7.

[0086] <Adhesive evaluation> The adhesives prepared in the examples and comparative examples were subjected to the following tests. The results are shown in Tables 4 to 6.

[0087] [Shear adhesive strength] Each adhesive composition was applied to a stainless steel substrate (100 mm long, 25 mm wide, 2 mm thick) to a width of 25 mm, length of 10 mm, and thickness of 0.1 mm, and then bonded to a carbon fiber reinforced plastic substrate (100 mm long, 25 mm wide, 2 mm thick), and then aged at 80°C for 1 day under pressure to maintain a thickness of 0.1 mm to obtain a test specimen. The shear adhesive strength of the obtained test specimen was measured using a tensile tester at a temperature of 25°C and a relative humidity of 50% at a pulling rate of 1 mm / min, and evaluated according to the following criteria. (Evaluation criteria) ◎: Shear adhesive strength is 10 MPa or more (very good) ○: Shear adhesive strength is 7 MPa or more and less than 10 MPa (good) △: Shear adhesive strength is 5 MPa or more and less than 7 MPa (usable) ×: Shear adhesive strength is less than 5 MPa (unusable)

[0088] [Breaking stress / breaking elongation] Each adhesive was filled into a 2 mm thick sheet mold, the surface was smoothed, and after curing at 80°C for one day, it was punched out using a No. 3 dumbbell mold to prepare dumbbell-shaped test pieces for evaluation. Using these dumbbell pieces, a tensile test was carried out at a tensile speed of 50 mm / min, and the breaking stress (MPa) and breaking elongation (%) were measured and evaluated according to the following criteria.

[0089] (Evaluation criteria for breaking stress) ◎: Breaking stress is 25 MPa or more (very good) ○: Breaking stress is 20 MPa or more and less than 25 MPa (good) △: Breaking stress is 15 MPa or more and less than 20 MPa (usable) ×: Breaking stress is less than 15 MPa (unusable)

[0090] (Evaluation criteria for breaking elongation) ◎: Breaking elongation is 600% or more (very good) ○: Breaking elongation is 500% or more and less than 600% (good) △: Breaking elongation is 400% or more and less than 500% (usable) ×: Breaking elongation is less than 400% (unusable)

[0091] [120℃ heat resistance] Dumbbell-shaped test pieces were prepared in the same manner as described above for [Break stress and break elongation]. These dumbbell-shaped test pieces were heat-treated in an environment of 120°C for 500 hours, and then subjected to a tensile test in the same manner as described above for [Break stress and break elongation] to measure the break stress (MPa) and break elongation (%). The rate of change in the test pieces before and after the test was calculated and evaluated according to the following criteria.

[0092] (Evaluation criteria for rate of change in breaking stress) ◎: The rate of change is less than 10% (very good) ○: The rate of change is 10% or more and less than 30% (good) △: Change rate is 30% or more and less than 50% (usable) ×: The rate of change is 50% or more (unusable)

[0093] (Evaluation criteria for rate of change in breaking elongation) ◎: The rate of change is less than 10% (very good) ○: The rate of change is 10% or more and less than 30% (good) △: Change rate is 30% or more and less than 50% (usable) ×: The rate of change is 50% or more (unusable)

[0094] Table 5 JPEG0007810060000005.jpg21599

[0095] Table 6 JPEG0007810060000006.jpg215102

[0096] Table 7 JPEG0007810060000007.jpg200104

[0097] The adhesive of the present invention exhibited good results in all of adhesive strength, breaking stress, breaking elongation, and heat resistance, whereas the adhesive of the comparative example exhibited results inferior to those of the examples in some or all of adhesive strength, breaking stress, breaking elongation, and heat resistance.

Claims

1. The composition contains a urethane-modified resin (C), an aromatic polyisocyanate (D), and a polyether polyol (A2), the urethane-modified resin (C) is a reaction product of a urethane prepolymer having an isocyanato group at its terminal and a monoamine compound having a molecular weight of less than 200; the urethane prepolymer is a reaction product of a polyol (A) including a polyether polyol (A1) and a polyisocyanate (B), the polyether polyol (A1) has structural units derived from a non-crystalline polyether polyol (E) and structural units derived from a crystalline polyether polyol (F), the monoamine compound having a molecular weight of less than 200 has a hydroxyl group or a sulfanyl group in the molecule, the content of the polyether polyol (A2) is in the range of 25 to 250 mass% based on the total mass of the urethane-modified resin (C); glue.

2. 2. The adhesive according to claim 1, comprising 30 to 65 mass% of the amorphous polyether polyol (E) and 35 to 70 mass% of the crystalline polyether polyol (F), based on the total mass of the polyol (A).

3. The adhesive of claim 1 , wherein the amorphous polyether polyol (E) comprises polypropylene glycol.

4. The adhesive of claim 1 , wherein the crystalline polyether polyol (F) comprises polytetramethylene ether glycol.

5. 2. The adhesive of claim 1, wherein the polyether polyol (A2) has a number average molecular weight of less than 750.

6. A cured product of the adhesive according to any one of claims 1 to 5.

7. A laminate having a layer comprising the cured product according to claim 6 on a substrate.

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