Urethane resin-forming composition, composition for urethane adhesives, adhesive for automobile structures, and cured product

Abstract

A urethane resin-forming composition containing a curing agent (A) containing a polyol, an isocyanate group-terminated prepolymer (B), and a compound (C), the compound (C) being a compound represented by formula (1): R1-NHCOO-R2 (1); in the formula, R1 and R2 are each independently an alkyl group, an alicyclic hydrocarbon group, an aryl group or a heterocyclic group.

Description

Technical Field

[0001] The present invention relates to a urethane resin-forming composition, a composition for a urethane adhesive, an adhesive for automobile structures, and a cured product. Background Art

[0002] Various adhesives are known, including epoxy adhesives and urethane adhesives. Structural adhesives require strength and durability. In particular, automotive applications require a high glass transition temperature (Tg) for strength stability within the operating temperature range. Generally, epoxy adhesives have a higher Tg and higher strength than urethane adhesives, but are brittle.

[0003] Therefore, among structural adhesives requiring toughness, carbamate adhesives have attracted attention. As carbamate adhesives, reactive two-component adhesives are sometimes used. As such adhesives, for example, Patent Document 1 discloses a carbamate adhesive composition, which is formed by a first component containing a prepolymer obtained by reacting a polyisocyanate with a polyol, and a second component containing a polyol and a catalyst. The first component is composed of a prepolymer obtained by reacting a polyisocyanate with a high molecular weight polyol (I) having a number average molecular weight of 1000 or more and a filler. The second component contains a high molecular weight polyol (II) having a number average molecular weight of 1000 or more and a low molecular weight polyol having a number average molecular weight of less than 1000, and the molar ratio of (I), (II) and the low molecular weight polyol is a specified amount. According to the two-component carbamate adhesive composition of Patent Document 1, the effect of maintaining good bonding performance is maintained without primer treatment or polishing treatment, and the storage stability of the first component is also excellent.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: International Publication No. 2009 / 047962 Summary of the Invention

[0007] Problems to be solved by the invention

[0008] However, although conventional urethane adhesives including the urethane adhesive composition described in Patent Document 1 have shown a certain tendency to improve toughness, the tendency is insufficient, and further improvement of toughness is required.

[0009] Therefore, one embodiment of the present disclosure can suitably provide a urethane resin-forming composition and a urethane adhesive composition that contribute to the production of a highly tough adhesive. Furthermore, another embodiment of the present disclosure can suitably provide a highly tough adhesive for automobile structures and a cured product.

[0010] Solutions for solving problems

[0011] According to one embodiment of the present disclosure, the following embodiments (1) to (15) are provided.

[0012] (1) A urethane resin-forming composition comprising:

[0013] A curing agent containing polyol (A),

[0014] Isocyanate group-terminated prepolymer (B), and

[0015] Compound (C),

[0016] The aforementioned compound (C) is a compound represented by formula (1):

[0017] R 1 -NHCOO-R 2 (1)

[0018] Where R 1 and R 2 Each is independently an alkyl group, an alicyclic hydrocarbon group, an aryl group or a heterocyclic group.

[0019] (2) The composition according to (1), wherein the curing agent (A) contains a crosslinking component (a-1).

[0020] (3) The composition according to (1), wherein the curing agent (A) contains at least one diol (a-2) selected from the group consisting of aliphatic diols and alicyclic diols.

[0021] (4) The composition according to (1), wherein the curing agent (A) comprises a crosslinking component (a-1), and

[0022] At least one diol (a-2) selected from the group consisting of aliphatic diols and alicyclic diols.

[0023] (5) The composition according to any one of (1) to (4), wherein the isocyanate group-terminated prepolymer (B) comprises a reaction product of a polyol (b-1) having a number average molecular weight of 500 or more, a polyisocyanate (b-2), and a crosslinking component (b-3) as an optional component.

[0024] (6) The composition according to (1), wherein the curing agent (A) comprises a crosslinking component (a-1) and at least one diol (a-2) selected from the group consisting of aliphatic diols and alicyclic diols,

[0025] The isocyanate group-terminated prepolymer (B) comprises a reaction product of a polyol (b-1) having a number average molecular weight of 500 or more, a polyisocyanate (b-2), and an optional crosslinking component (b-3).

[0026] (7) The composition according to any one of (1) to (6), wherein the isocyanate group-terminated prepolymer (B) comprises a reaction product of a polyol (b-1) having a number average molecular weight of 500 or more, a polyisocyanate (b-2), and an optional crosslinking component (b-3);

[0027] The polyol (b-1) has a carbonate bond.

[0028] (8) The composition according to (1), wherein the curing agent (A) comprises a crosslinking component (a-1) and at least one diol (a-2) selected from the group consisting of aliphatic diols and alicyclic diols,

[0029] The isocyanate group-terminated prepolymer (B) comprises a reaction product of a polyol (b-1) having a number average molecular weight of 500 or more, a polyisocyanate (b-2), and an optional crosslinking component (b-3).

[0030] The polyol (b-1) has a carbonate bond.

[0031] (9) The composition according to any one of (1) to (8), wherein a urethane group concentration of a resin obtained by curing the urethane resin-forming composition is 2000 mmol / kg or more and 5000 mmol / kg or less.

[0032] (10) The composition according to any one of (1) to (9), wherein the total content of the crosslinkable groups possessed by the curing agent (A) and the content of the crosslinkable groups possessed by the isocyanate group-terminated prepolymer (B) in the urethane resin-forming composition is 50 mmol / kg or more and 1000 mmol / kg or less.

[0033] (11) The composition according to any one of (1) to (10), wherein the compound (C) has a melting point of 100°C or lower.

[0034] (12) A composition for a urethane adhesive, comprising the urethane resin-forming composition according to any one of (1) to (11).

[0035] (13) The composition according to (12), wherein the content of the solvent is 1.0% by mass or less.

[0036] (14) An adhesive for automobile structures, comprising the composition described in (12).

[0037] (15) A cured product, which is a cured product of the composition according to any one of (1) to (11).

[0038] Effects of the Invention

[0039] According to one embodiment of the present disclosure, a urethane resin-forming composition and a urethane adhesive composition that contribute to the production of a highly tough adhesive can be provided. Furthermore, according to another embodiment of the present invention, a highly tough adhesive for automobile structures and a cured product can be provided. DETAILED DESCRIPTION

[0040] Hereinafter, exemplary embodiments for implementing each mode of the present disclosure will be described in detail.

[0041] It should be noted that, in this specification, a numerical range expressed using "to" indicates a range that includes the numerical values ​​described before and after "to" as the minimum value and the maximum value, respectively. The minimum value or maximum value of a numerical range expressed using "to", "above", or "below" can be arbitrarily combined with the maximum value or minimum value of another numerical range expressed using "to", "above", or "below". In addition, upper limits and lower limits described separately can also be arbitrarily combined.

[0042] [Urethane resin-forming composition]

[0043] The urethane resin-forming composition according to one embodiment of the present disclosure includes:

[0044] A curing agent containing polyol (A),

[0045] Isocyanate group-terminated prepolymer (B), and

[0046] Compound (C),

[0047] The compound (C) is a compound represented by formula (1):

[0048] R 1 -NHCOO-R 2 (1)

[0049] Where R 1 and R 2 Each is independently an alkyl group, an alicyclic hydrocarbon group, an aryl group or a heterocyclic group.

[0050] By adding the compound (C) to the urethane resin-forming composition containing the polyol-containing curing agent (A) and the isocyanate group-terminated prepolymer (B), a urethane resin-forming composition having high toughness can be obtained.

[0051] The reason why the cured product of the urethane resin-forming composition according to one embodiment of the present disclosure exhibits high toughness is not necessarily certain, but the present inventors speculate as follows.

[0052] Specifically, a urethane resin-forming composition according to one embodiment of the present disclosure comprises a polyol-containing curing agent (A), an isocyanate group-terminated prepolymer (B), and a compound (C), wherein the compound (C) is a compound represented by formula (1). It is speculated that when the compound represented by formula (1) is added to the urethane resin-forming composition comprising the polyol-containing curing agent (A) and the isocyanate group-terminated prepolymer (B), the extremely localized movement of the flexible chain segments is suppressed, thereby significantly reducing the flexibility of the resin as a whole and improving the rigidity, resulting in improved toughness.

[0053] [[Curing agent (A)]]

[0054] The curing agent (A) may contain a crosslinking component (a-1),

[0055] At least one diol (a-2) selected from the group consisting of aliphatic diols and alicyclic diols may be contained.

[0056] The crosslinking component (a-1) and at least one diol (a-2) selected from aliphatic diols and alicyclic diols may be contained.

[0057] Examples of the cross-linking component (a-1) include polyols having an average number of functional groups of 3 or more.

[0058] Examples of polyols having an average number of functional groups of 3 or greater include glycerin, trimethylolpropane, pentaerythritol, N,N-bishydroxypropyl-N-hydroxyethylamine, triethanolamine, triisopropanolamine, monomeric polyols of ethylenediamine propylene oxide-modified products, monomeric polyols of trimethylolpropane propylene oxide-modified products, and pentaerythritol propylene oxide-modified products. Furthermore, examples include polycaprolactone polyols obtained by ring-opening addition of cyclic esters such as ε-caprolactone, β-butyrolactone, γ-butyrolactone, γ-valerolactone, and δ-valerolactone to polyols such as glycerin, trimethylolpropane, and pentaerythritol as initiators.

[0059] The cross-linking component (a-1) may contain only one kind of these or two or more kinds of them.

[0060] Among the diols (a-2), examples of the aliphatic diol include aliphatic diol monomers and aliphatic diol polymers, and examples of the alicyclic diol include alicyclic diol monomers and alicyclic diol polymers.

[0061] Examples of the aliphatic diol monomer include ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,8-octanediol, 1,9-nonanediol, 3-methyl-1,5-pentanediol, 3,3-dimethylolheptane, and neopentyl glycol; diethylene glycol, and dipropylene glycol.

[0062] Examples of the alicyclic diol monomer include 1,4-cyclohexanediol, cycloheptanediol, cyclooctanediol, 1,4-cyclohexanedimethanol, hydroxypropylcyclohexanol, isohexide, tricyclo[5.2.1.02,6]decane-4,8-dimethanol, and alkylene oxide adducts thereof.

[0063] Examples of the aliphatic or alicyclic diol polymer include aliphatic or alicyclic diol polymers containing one or more bonds selected from the group consisting of ester bonds, ether bonds, and carbonate bonds. More preferred are aliphatic or alicyclic polyester diols, aliphatic or alicyclic polyether diols, and aliphatic or alicyclic polycarbonate diols. Even more preferred are aliphatic or alicyclic polyether diols.

[0064] Examples of the aliphatic or alicyclic polycarbonate diol include those obtained by dealcoholization or dephenolization of one or more aliphatic or alicyclic diols such as ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,8-octanediol, 1,9-nonanediol, 3-methyl-1,5-pentanediol, 3,3-dimethylolheptane, diethylene glycol, dipropylene glycol, neopentyl glycol, cyclohexane-1,4-diol, cyclohexane-1,4-dimethanol, and dimer acid diol with one or more aliphatic or alicyclic carbonates such as dialkyl carbonates such as dimethyl carbonate and diethyl carbonate, or alkylene carbonates such as ethylene carbonate and propylene carbonate.

[0065] Examples of the aliphatic or alicyclic polyester diol include succinic acid, tartaric acid, oxalic acid, malonic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, glutaconic acid, azelaic acid, sebacic acid, 1,4-cyclohexanedicarboxylic acid, 2-hexenedioic acid (α-Hydromuconic acid), trans-2-butene-1,4-dicarboxylic acid (β-Hydromuconic acid), A substance obtained by a polycondensation reaction of one or more aliphatic or alicyclic dicarboxylic acids such as α-butyl-α-ethylglutaric acid, α,β-diethylsuccinic acid, maleic acid, and fumaric acid, or anhydrides thereof, with one or more aliphatic or alicyclic diols such as ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,8-octanediol, 1,9-nonanediol, 3-methyl-1,5-pentanediol, 3,3-dihydroxymethylheptane, diethylene glycol, dipropylene glycol, neopentyl glycol, cyclohexane-1,4-diol, cyclohexane-1,4-dimethanol, and dimer acid diol. Examples of the aliphatic or alicyclic polyester diol include polyester-amide diols obtained by replacing part of an aliphatic or alicyclic diol acid with an aliphatic or alicyclic diamine acid such as hexamethylenediamine or isophoronediamine, or an aliphatic or alicyclic amino alcohol such as monoethanolamine.

[0066] Examples of the aliphatic or alicyclic polyether diol include polyether diols obtained by addition polymerization of alkylene oxides such as ethylene oxide, propylene oxide, and butylene oxide using aliphatic or alicyclic diol acids such as ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,8-octanediol, 1,9-nonanediol, 3-methyl-1,5-pentanediol, 3,3-dimethylolheptane, diethylene glycol, dipropylene glycol, neopentyl glycol, cyclohexane-1,4-diol, cyclohexane-1,4-dimethanol, and dimer acid diol; or aliphatic or alicyclic compounds having two active hydrogen groups such as aliphatic or alicyclic diamine acids such as ethylenediamine and propylenediamine as initiators. Examples of the polyether diol include polyether diols obtained by ring-opening polymerization of alkyl glycidyl ethers such as methyl glycidyl ether and cyclic ether monomers such as tetrahydrofuran.

[0067] The diol (a-2) may contain only one kind of these or two or more kinds of them.

[0068] The number average molecular weight of the diol (a-2) is preferably 4000 g / mol or less, more preferably 2500 g / mol or less, and further preferably 1500 g / mol or less.

[0069] In addition, the number average molecular weight in this disclosure may be a number average molecular weight obtained by a measurement method capable of high-precision measurement, and for example, a number average molecular weight measured by a method (titration method) in accordance with JIS K 0070-1992 can be used.

[0070] [[Isocyanate group-terminated prepolymer (B)]]

[0071] The isocyanate group-terminated prepolymer (B) comprises a reaction product of a polyol (b-1) having a number average molecular weight of 500 or more, a polyisocyanate (b-2), and an optional crosslinking component (b-3).

[0072] Examples of the polyol (b-1) having a number average molecular weight of 500 or more include polyols having a number average molecular weight of 500 or more and having at least one bond selected from the group consisting of an ester bond, an ether bond, and a carbonate bond, preferably having a carbonate bond. Polyester polyols, polyether polyols, and polycarbonate polyols are more preferred, polyether polyols and polycarbonate polyols are more preferred, and polycarbonate polyols are still more preferred.

[0073] Examples of the polycarbonate polyol include ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,8-octanediol, 1,9-nonanediol, 3-methyl-1,5-pentanediol, 3,3-dimethylolheptane, diethylene glycol, dipropylene glycol, neopentyl glycol, cyclohexane-1,4-diol, cyclohexane-1,4-dimethanol, and glycerol. One or more polyols such as oil, trimethylolpropane, dimer diol, ethylene oxide and propylene oxide adducts of bisphenol A, bis(β-hydroxyethyl)benzene, benzyl alcohol, etc., and dialkyl carbonates such as dimethyl carbonate and diethyl carbonate; alkylene carbonates such as ethylene carbonate and propylene carbonate; diphenyl carbonate; one or more carbonates such as dinaphthyl carbonate, dianthryl carbonate, diphenanthryl carbonate, diindan carbonate; substances obtained by dealcoholization or dephenolization.

[0074] Examples of polyester polyols include phthalic acid, isophthalic acid, terephthalic acid, naphthalene dicarboxylic acid, succinic acid, tartaric acid, oxalic acid, malonic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, glutaconic acid, azelaic acid, sebacic acid, 1,4-cyclohexanedicarboxylic acid, 2-hexenedicarboxylic acid (α-Hydromuconic acid), trans-2-butene-1,4-dicarboxylic acid (β-Hydromuconic acid), Polyester polyols obtained by the polycondensation reaction of one or more dicarboxylic acids such as 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,8-octanediol, 1,9-nonanediol, 3-methyl-1,5-pentanediol, 3,3-dihydroxymethylheptane, diethylene glycol, dipropylene glycol, neopentyl glycol, cyclohexane-1,4-diol, cyclohexane-1,4-dimethanol, glycerin, trimethylolpropane, dimer acid diol, ethylene oxide or propylene oxide adducts of bisphenol A, bis(β-hydroxyethyl)benzene, benzyl alcohol, etc. Examples of the polyol (b-1) include polyester-amide polyols obtained by replacing part of these alcohols with low-molecular-weight polyamines such as hexamethylenediamine, isophoronediamine, and monoethanolamine, or low-molecular-weight amino alcohols.

[0075] Examples of the polyether polyol include ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,8-octanediol, 1,9-nonanediol, 3-methyl-1,5-pentanediol, 3,3-dihydroxymethylheptane, diethylene glycol, dipropylene glycol, neopentyl glycol, cyclohexane-1,4-diol, Polyether polyols are obtained by addition polymerization of alkylene oxides such as ethylene oxide, propylene oxide, and butylene oxide using compounds having two active hydrogen groups, such as cyclohexane-1,4-dimethanol, dimer diol, bisphenol A, bis(β-hydroxyethyl)benzene, and benzyl alcohol; or low molecular weight polyamines such as ethylenediamine, propylenediamine, toluenediamine, m-phenylenediamine, diphenylmethanediamine, and benzylenediamine. Examples of polyether polyols include those obtained by ring-opening polymerization of alkyl glycidyl ethers such as methyl glycidyl ether, aryl glycidyl ethers such as phenyl glycidyl ether, and cyclic ether monomers such as tetrahydrofuran.

[0076] The polyol (b-1) may contain only one kind of these or two or more kinds of them.

[0077] The number average molecular weight of the polyol (b-1) is preferably 500 or more and 10,000 or less, more preferably 500 or more and 7,000 or less, and even more preferably 500 or more and 4,000 or less.

[0078] Examples of the polyisocyanate (b-2) include polyisocyanates having two or more isocyanate groups in the molecule.

[0079] Examples of polyisocyanates include organic polyisocyanates. Examples of organic polyisocyanates include aromatic polyisocyanates, aromatic aliphatic polyisocyanates, aliphatic polyisocyanates, and alicyclic polyisocyanates. These may contain only one type or two or more types. Among these, aromatic polyisocyanates are preferred from the viewpoints of reactivity and viscosity.

[0080] Examples of the aromatic polyisocyanate include 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, a 2,4-toluene diisocyanate / 2,6-toluene diisocyanate mixture, 2,2'-diphenylmethane diisocyanate, 4,4'-diphenylmethane diisocyanate, a 2,2'-diphenylmethane diisocyanate / 4,4'-diphenylmethane diisocyanate mixture, 2,4'-diphenylmethane diisocyanate, a 2,4'-diphenylmethane diisocyanate / 4,4'-diphenylmethane diisocyanate mixture, and 2,2'-diphenylmethane diisocyanate. / 2,4'-diphenylmethane diisocyanate / 4,4'-diphenylmethane diisocyanate mixture, 4,4'-diphenyl ether diisocyanate, 2-nitrodiphenyl-4,4'-diisocyanate, 2,2'-diphenylpropane-4,4'-diisocyanate, 3,3'-dimethyldiphenylmethane-4,4'-diisocyanate, 4,4'-diphenylpropane diisocyanate, m-phenylene diisocyanate, p-phenylene diisocyanate, naphthylene-1,4-diisocyanate, naphthylene-1,5-diisocyanate, 3,3'-dimethoxydiphenyl-4,4'-diisocyanate, etc.

[0081] Examples of the aromatic aliphatic polyisocyanate include 1,3-xylylenediisocyanate, 1,4-xylylenediisocyanate, a 1,3-xylylenediisocyanate / 1,4-xylylenediisocyanate mixture, 1,3-bis(1-isocyanato-1-methylethyl)benzene, 1,4-bis(1-isocyanato-1-methylethyl)benzene, a 1,3-bis(1-isocyanato-1-methylethyl)benzene / 1,4-bis(1-isocyanato-1-methylethyl)benzene mixture, and ω,ω′-diisocyanato-1,4-diethylbenzene.

[0082] Examples of the aliphatic polyisocyanate include tetramethylene diisocyanate, hexamethylene diisocyanate, 2-methylpentane-1,5-diisocyanate, 3-methylpentane-1,5-diisocyanate, lysine diisocyanate, trioxyethylene diisocyanate, ethylene diisocyanate, trimethylene diisocyanate, octamethylene diisocyanate, nonamethylene diisocyanate, 2,2'-dimethylpentane diisocyanate, 2,2,4-trimethylhexane diisocyanate, decamethylene diisocyanate, butene diisocyanate, 1,3-butadiene-1,4-diisocyanate, 2,4,4- Trimethylhexamethylene diisocyanate, 1,6,11-undecane triisocyanate, 1,3,6-hexamethylene triisocyanate, 1,8-diisocyanate-4-isocyanatomethyloctane, 2,5,7-trimethyl-1,8-diisocyanate-5-isocyanatomethyloctane, bis(isocyanatoethyl) carbonate, bis(isocyanatoethyl) ether, 1,4-butanediol dipropyl ether-α,α'-diisocyanate, lysine diisocyanate methyl ester, 2-isocyanatoethyl-2,6-diisocyanate hexanoate, 2-isocyanatopropyl-2,6-diisocyanate hexanoate, etc.

[0083] Examples of the alicyclic polyisocyanate include isophorone diisocyanate, cyclohexane diisocyanate, bis(isocyanatomethyl)cyclohexane, dicyclohexylmethane diisocyanate, methylcyclohexane diisocyanate, dicyclohexyldimethylmethane diisocyanate, 2,2'-dimethyldicyclohexylmethane diisocyanate, bis(4-isocyanato-n-butylidene)pentaerythritol, hydrogenated hydrogenated dimer acid diisocyanate, 2-isocyanatomethyl-3-(3-isocyanatomethyl)pentaerythritol, and the like. 2-Isocyanatomethyl-3-(3-isocyanatopropyl)-6-isocyanatomethyl-bicyclo[2.2.1]-heptane, 2-Isocyanatomethyl-2-(3-isocyanatopropyl)-5-isocyanatomethyl-bicyclo[2.2.1]-heptane, 2-Isocyanatomethyl-2-(3-isocyanatopropyl)-6-isocyanatomethyl-bicyclo[2.2.1]-heptane, .2.1]-heptane, 2-isocyanatomethyl-3-(3-isocyanatopropyl)-5-(2-isocyanatoethyl)-bicyclo[2.2.1]-heptane, 2-isocyanatomethyl-3-(3-isocyanatopropyl)-6-(2-isocyanatoethyl)-bicyclo[2.2.1]-heptane, 2-isocyanatomethyl-2-(3-isocyanatopropyl)-5-(2-isocyanatoethyl)-bicyclo[2.2.1]-heptane, 2-isocyanatomethyl-2-(3-isocyanatopropyl)-6-(2-isocyanatoethyl)-bicyclo[2.2.1]-heptane, 2,5-bis(isocyanatomethyl)-bicyclo[2.2.1]-heptane, hydrogenated diphenylmethane diisocyanate, norbornane diisocyanate, hydrogenated toluene diisocyanate, hydrogenated xylene diisocyanate, hydrogenated tetramethylxylene diisocyanate, etc.

[0084] The polyisocyanate may contain only one kind of these or two or more kinds of them.

[0085] The content of the polyisocyanate (b-2) in the urethane resin-forming composition is preferably 750 mmol / kg to 3000 mmol / kg, and more preferably 1000 mmol / kg to 2500 mmol / kg.

[0086] The isocyanate group-terminated prepolymer (B) contains a crosslinking component (b-3) as an optional component. That is, the isocyanate group-terminated prepolymer (B) may further contain a structure derived from the crosslinking component (b-3).

[0087] Examples of the cross-linking component (b-3) include the same cross-linking components as those for the cross-linking component (a-1).

[0088] [[Content of cross-linking groups]]

[0089] The total content of the crosslinkable group of the curing agent (A) and the content of the crosslinkable group of the isocyanate group-terminated prepolymer (B) (i.e., crosslinking density) in the urethane resin forming composition is preferably 25 mmol / kg or more and 1200 mmol / kg or less, more preferably 50 mmol / kg or more and 1000 mmol / kg or less, further preferably 100 mmol / kg or more and 800 mmol / kg or less, and particularly preferably 150 mmol / kg or more and 700 mmol / kg or less. When the content of the crosslinkable group is within this range, the fracture toughness value (G Ic ) becomes higher and has better toughness, so it is preferred.

[0090] In addition, when the urethane resin-forming composition does not contain a crosslinking group other than the crosslinking component (a-1) and the crosslinking component (b-3), the total content of the crosslinking group possessed by the curing agent (A) and the content of the crosslinking group possessed by the isocyanate group-terminated prepolymer (B) is consistent with the total content of the crosslinking group possessed by the crosslinking component (a-1) and the crosslinking component (b-3).

[0091] Here, the crosslinkable group refers to a functional group that forms a crosslink.

[0092] Therefore, if a trifunctional polyol (e.g., glycerol) is used as an example, one hydroxyl group in one molecule forms a crosslink, and the remaining two hydroxyl groups do not participate in the crosslinking. Therefore, in this case, the number of crosslinkable groups is one. That is, in the case of a trifunctional polyol, since the trifunctional polyol has one crosslinkable group, the content of the crosslinkable group is synonymous with the content of the trifunctional polyol.

[0093] [[Properties of the curing agent (A) and the isocyanate group-terminated prepolymer (B)]]

[0094] It is preferred that at least one of the polyol (b-1) and the polyisocyanate (b-2) be liquid at 25° C. and 1 atmosphere.

[0095] It is preferred that at least one of the curing agent (A) and the isocyanate group-terminated prepolymer (B) is liquid at 25° C. and 1 atmosphere.

[0096] [[Embodiment of Combination of Curing Agent (A) and Isocyanate Group-Terminated Prepolymer (B)]]

[0097] Implementation Method 1

[0098] The curing agent (A) comprises a crosslinking component (a-1) and at least one diol (a-2) selected from the group consisting of aliphatic diols and alicyclic diols.

[0099] The isocyanate group-terminated prepolymer (B) comprises a reaction product of a polyol (b-1) having a number average molecular weight of 500 or more, a polyisocyanate (b-2), and an optional crosslinking component (b-3).

[0100] Implementation Method 2

[0101] The curing agent (A) comprises a crosslinking component (a-1) and at least one diol (a-2) selected from the group consisting of aliphatic diols and alicyclic diols.

[0102] The isocyanate group-terminated prepolymer (B) comprises a reaction product of a polyol (b-1) having a number average molecular weight of 500 or more, a polyisocyanate (b-2), and an optional crosslinking component (b-3).

[0103] The polyol (b-1) has a carbonate bond.

[0104] In addition, the urethane resin-forming composition of this aspect is not limited at all by these embodiments.

[0105] [[Compound (C)]]

[0106] Compound (C) is a compound represented by formula (1) and has one urethane bond in one molecule:

[0107] R 1 -NHCOO-R 2 (1)

[0108] Where R 1 and R 2 Each is independently an alkyl group, an alicyclic hydrocarbon group, an aryl group or a heterocyclic group.

[0109] The number of carbon atoms in the alkyl group is preferably 1 to 8, more preferably 1 to 5, and particularly preferably 1 to 3. When the number of carbon atoms in the alkyl group is within the above range, the alkyl group is well matched with the size of the molecular chain and tends to impart high toughness.

[0110] Examples of the alicyclic hydrocarbon group include a cyclohexyl group, a cyclopentyl group, a decahydronaphthyl group, etc. The alicyclic hydrocarbon group may have a substituent, and examples of the substituent include a linear or branched saturated hydrocarbon group.

[0111] Examples of the aryl group include a phenyl group, a naphthyl group, etc. The aryl group may have a substituent, and examples of the substituent include a linear or branched saturated hydrocarbon group.

[0112] Examples of the heterocyclic group include a pyrrole ring, a furan ring, a thienyl group, a phosphasol ring, etc. The heterocyclic group may have a substituent, and examples of the substituent include a linear or branched saturated hydrocarbon group.

[0113] As R in compound (C) 1 With R 2 From the viewpoint of miscibility with the urethane resin, melting point, etc., a combination of an alkyl group (preferably a methyl group or an ethyl group) and an alkyl group (preferably a methyl group or an ethyl group), and a combination of an alkyl group (preferably a methyl group or an ethyl group) and an aryl group (preferably a phenyl group) are preferred.

[0114] Specific examples of compound (C) include methyl N-methylcarbamate, ethyl N-methylcarbamate, methyl N-ethylcarbamate, ethyl N-ethylcarbamate, ethyl N-phenylcarbamate, and methyl N-phenylcarbamate. From the viewpoint of obtaining an adhesive having high toughness, methyl N-methylcarbamate, ethyl N-methylcarbamate, ethyl N-phenylcarbamate, and methyl N-phenylcarbamate are preferred; methyl N-methylcarbamate, ethyl N-methylcarbamate, and ethyl N-phenylcarbamate are more preferred; and methyl N-methylcarbamate is particularly preferred.

[0115] The melting point of compound (C) as measured in accordance with JIS K0064:1992 is preferably 100°C or lower, more preferably 90°C or lower, and even more preferably 75°C or lower. The lower limit of the melting point of compound (C) is preferably -90°C or higher. When the melting point of compound (C) is at least the lower limit, it is easily dispersed uniformly in the urethane resin, and a stable toughness-enhancing effect is easily achieved.

[0116] The content of compound (C) is preferably 1 mass % or more and 30 mass % or less in carbamate resin forming composition, more preferably 2 mass % or more and 25 mass % or less, further preferably 3 mass % or more and 20 mass % or less, particularly preferably 4 mass % or more and 18 mass % or less. When the content of compound (C) is above the aforementioned lower limit, it is easy to more significantly obtain the effect of toughness improvement. In addition, when the content of compound (C) is below the aforementioned upper limit, carbamate resin will not reflect the characteristic of compound (C), and it is easy to obtain the effect of toughness improvement.

[0117] The number average molecular weight of compound (C) is preferably 80 or more and 1000 or less, more preferably 100 or more and 800 or less, further preferably 120 or more and 600 or less, and particularly preferably 140 or more and 400 or less. When the number average molecular weight of compound (C) is above the aforementioned lower limit, the molecular chain of the urethane resin and the molecular size of compound (C) are well matched, and there is a tendency to impart higher toughness. In addition, when the number average molecular weight of compound (C) is below the aforementioned upper limit, from the viewpoint of the viscosity and crystallinity of compound (C), it can be handled more stably.

[0118] The compound (C) may be added to either or both of the curing agent (A) and the isocyanate group-terminated prepolymer (B) to form a two-component adhesive, or may be used alone to form a three-component adhesive.

[0119] The carbamate group concentration of the resin obtained by curing the carbamate resin forming composition is preferably more than 2000mmol / kg and less than 5500mmol / kg, more preferably more than 2000mmol / kg and less than 5000mmol / kg, further preferably more than 2600mmol / kg and less than 4800mmol / kg, particularly preferably more than 2800mmol / kg and less than 4500mmol / kg. When the carbamate group concentration of resin is more than the aforementioned lower limit, resin strength fully becomes high and can give high toughness. In addition, if the carbamate group concentration of resin is below the aforementioned upper limit, the brittleness of resin can be suppressed, thus more easily obtaining the synergistic effect of adding compound (C).

[0120] [Physical properties, characteristics, and morphology of the urethane resin-forming composition]]

[0121] The glass transition temperature of the resin obtained by curing the urethane resin-forming composition is preferably 60° C. or higher, more preferably 65° C. or higher, and even more preferably 70° C. or higher. In particular, in automotive applications, a glass transition temperature within this range is required from the viewpoint of strength stability within the operating temperature range.

[0122] The glass transition temperature (Tg) is measured using a viscoelasticity measuring device. The measurement mode is not limited to a specific mode, and shear, compression, three-point bending or tensile measurement modes can be used. The peak temperature of the loss tangent (tanδ) when the measurement frequency is set to 10 Hz, the heating rate is set to 2°C / min, and the measurement temperature range is set to -150°C to 250°C is taken as Tg.

[0123] From the viewpoint of handleability, the urethane resin-forming composition is preferably liquid (ie, has fluidity) at 25° C. and 1 atmosphere.

[0124] It is preferred that at least one of the curing agent (A) and the isocyanate group-terminated prepolymer (B) is liquid at 25° C. and 1 atmosphere.

[0125] The urethane resin-forming composition comprises a curing agent (A), an isocyanate group-terminated prepolymer (B), and a compound (C). These may be a three-component type in which they are present separately, or a two-component type in which the compound (C) is mixed with at least one of the curing agent (A) and the isocyanate group-terminated prepolymer (B). The temperature and time for mixing the curing agent (A), the isocyanate group-terminated prepolymer (B), and the compound (C) can be, for example, 10 to 35°C and 1 to 60 minutes.

[0126] The method for mixing the curing agent (A) and the isocyanate group-terminated prepolymer (B) is not particularly limited, and for example, they may be mixed manually with a spatula, or may be mixed using a mechanical rotary mixer, static mixer, or the like.

[0127] [Urethane Adhesive Composition]

[0128] The urethane adhesive composition according to one embodiment of the present disclosure includes the urethane resin-forming composition described above.

[0129] The urethane adhesive composition may contain other components in addition to the urethane resin-forming composition. Other components are preferably those that do not react when the curing agent (A), the isocyanate group-terminated prepolymer (B), and the compound (C) are mixed. Examples of other components include additives other than the components that constitute the urethane resin, such as fillers, colorants, antistatic agents, and preservatives.

[0130] The composition for urethane adhesives may contain a solvent, but the content of the solvent is preferably 1.0% by mass or less.

[0131] The urethane adhesive composition may be substantially free of solvent, that is, may be a solvent-free composition. However, if it contains a solvent as an impurity, it falls within the category of being substantially free of solvent.

[0132] [Adhesives for automotive structures]

[0133] An automotive structural adhesive according to one embodiment of the present disclosure comprises the above-mentioned urethane adhesive composition. The fracture toughness value (G Ic ) is high and has excellent toughness.

[0134] [cured material]

[0135] A cured product according to one embodiment of the present disclosure is a cured product of the above-mentioned urethane resin-forming composition.

[0136] Example

[0137] Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to the following examples.

[0138] [Preparation of urethane resin-forming composition]

[0139] [raw material]

[0140] "MT": Millionate MT (monomer MDI, manufactured by Tosoh Corporation),

[0141] Average molecular weight 250, f=2

[0142] "TMP": trimethylolpropane (manufactured by Mitsubishi Gas Chemical Co., Ltd.),

[0143] Average molecular weight 134, f=3

[0144] "PCD3000": Polycarbonate polyol N-968

[0145] (Made by Tosoh Corporation),

[0146] Average molecular weight 3000, f=2

[0147] "PCD1000": Polycarbonate polyol N-965

[0148] (Made by Tosoh Corporation),

[0149] Average molecular weight 1000, f = 2

[0150] "PCD500": Polycarbonate polyol

[0151] Kuraray Polyol C-590 (manufactured by Kuraray Co., Ltd.),

[0152] Hydroxyl value = 222.3 KOH mg / g, f = 2

[0153] "BG": Butanediol (manufactured by Mitsubishi Chemical Corporation),

[0154] 1,4-Butanediol, average molecular weight 90, f=2

[0155] "CHDM": 1,4-cyclohexanedimethanol

[0156] (Made by Tokyo Chemical Industry Co., Ltd.)

[0157] PTMG250 (Mitsubishi Chemical Corporation)

[0158] Polytetramethylene ether glycol, average molecular weight 210, f=2

[0159] "MDEA": N-methyldiethanolamine (manufactured by Tokyo Chemical Industry Co., Ltd.), average molecular weight = 119, f = 2

[0160] "p-TolylDEA"; 2,2'-(p-tolylimino)diethanol (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.)

[0161] N-phenylurethane; N-phenylurethane (phenylurethane) (Tokyo Chemical Industry Co., Ltd., phenylurethane), melting point 52°C

[0162] "Methyl N-phenylcarbamate"; Methyl N-phenylcarbamate (manufactured by Tokyo Chemical Industry Co., Ltd.), melting point 47°C

[0163] "N-Methylurethane"; N-Methylurethane (manufactured by Tokyo Chemical Industry Co., Ltd.)

[0164] "Methyl N-methylcarbamate"; Methyl N-methylcarbamate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.)

[0165] "Diisononyl phthalate"; diisononyl phthalate (manufactured by Tokyo Chemical Industry Co., Ltd.), melting point <20°C

[0166] Talc: CROWN TALC R (Matsumura Industrial Co., Ltd.)

[0167] Zeolite: Zeoram A-3 (manufactured by Tosoh Corporation)

[0168] "Ethyl methyl sulfone": Ethyl methyl sulfone (manufactured by Tokyo Chemical Industry Co., Ltd.), melting point 34°C

[0169] "Ethyl phenyl sulfone": Ethyl phenyl sulfone (manufactured by Tokyo Chemical Industry Co., Ltd.), melting point 42°C

[0170] "Tributylphosphine oxide": Tributylphosphine oxide (manufactured by Tokyo Chemical Industry Co., Ltd.), melting point 71°C

[0171] Trioctylphosphine oxide: Trioctylphosphine oxide (manufactured by Tokyo Chemical Industry Co., Ltd.), melting point 54°C

[0172] (Examples 1 to 15)

[0173] In a 2L stirring container filled with nitrogen, the raw materials of the curing agent are added according to the formula shown in Tables 1 to 14 and stirred. While the temperature in the stirring container is maintained at 70 to 80°C, the mixture is stirred for about 1 to 3 hours to obtain various curing agents (A). It should be noted that "R (resin)" in Table 1 represents the ratio of NCO groups to OH groups (NCO / OH), which is a value that can be adjusted by the mixing amount of the main agent and the mixing amount of the curing agent. In addition, in each of Examples 1 to 12, the example on the right side recorded with "-" represents an example without adding filler, and the example on the left side represents an example with adding filler. Therefore, the fracture toughness value (G Ic ), the cohesion failure rate was measured in the case where fillers were added, and Tg was measured in the case where no fillers were added.

[0174] Separately, the raw materials for the main component (isocyanate group-terminated prepolymer) (B) were placed in a 2 L stirring vessel filled with nitrogen according to the formulations shown in Tables 1 to 14 and stirred. A urethanization reaction was then carried out for approximately 2 to 5 hours while maintaining the temperature in the stirring vessel at 70 to 80°C, thereby obtaining various isocyanate group-terminated prepolymers (B).

[0175] [DCB test (fracture toughness value)]

[0176] The DCB test was performed according to ASTM D3433-99.

[0177] Resin thickness: Adjust to 0.35mm using spacers

[0178] Teflon (registered trademark) tape was used as the spacer.

[0179] Test piece shape: Contoured type

[0180] Test base material: S50C steel (chemical nickel plating)

[0181] Test conditions: tensile test at 2 mm / min, and the fracture toughness value G is calculated based on the maximum load. Ic

[0182] Calculation formula: G Ic =[4L2(max)](m) / [EB2]

[0183] L(max) load: (N)

[0184] Young's modulus of E substrate (MPa): 208000

[0185] Width of base material B (mm): 25.49

[0186] m constant (based on contoured type): 3.54

[0187] The compound (C) preheated to 70° C. is added to the main component (isocyanate group-terminated prepolymer (B)) so that the amount of the compound (C) in the resin composition becomes 2.5 to 10% by mass, and mixed and degassed.

[0188] Next, fillers (50% by mass of talc / 50% by mass of zeolite) were added to the mixture of compound (C) and the main agent so that the amount of filler in the system would become 1 / 3, followed by mixing and degassing.

[0189] The curing agent (A) was further added and stirred for 30 seconds before being applied to the substrate and fixed with a jig. The curing was then carried out in two steps at 25°C for 30 minutes and 180°C for 30 minutes.

[0190] In order to give the substrate a preliminary crack, a 0.35mm thick Teflon (registered trademark) seal of 4.9 cm was pasted from the front end. In addition, in order to make the coating thickness of the adhesive uniform, a Teflon (registered trademark) seal of the same thickness of about 2 cm was pasted from the rear of the substrate.

[0191] The fracture toughness value (G Ic ) are shown in Tables 1 to 14. In addition, SCF in Tables 1 to 14 means the occurrence of thin layer cohesive failure (Special Cohesive Failure).

[0192] [Cohesive failure rate]

[0193] The broken surface of the sample was visually observed to measure the area ratio of the broken portion of the adhesive layer. The measurement results are shown in Tables 1 to 14.

[0194] Cohesive failure: the state of resin layer failure

[0195] Interface failure: The state where the resin peels off at the interface of the substrate

[0196] [Tg measurement (viscoelasticity measurement)]

[0197] The compound (C) preliminarily heated to 70° C. is added to the main component (B) so that the amount of the compound (C) in the resin composition becomes 2.5 to 10% by mass, and the mixture is mixed and degassed.

[0198] The curing agent (A) was further added, and the mixture was stirred and mixed for 30 seconds, followed by degassing for 30 to 60 seconds, and poured into a mold having a thickness of 2 mm to form a urethane resin.

[0199] The molded resin was punched out with a punching machine into pieces with a width of 5 mm and a length of 5 cm to obtain dumbbell-shaped test pieces.

[0200] Tg was obtained from the peak temperature of the loss tangent (tan δ) in a measurement mode of tension, a measurement frequency of 10 Hz, a heating rate of 2°C / min, and a measurement temperature range of -150°C to 250°C using a viscoelasticity measuring apparatus (DMA7100; Hitachi High-Technologies Corporation).

[0201] (Comparative Examples 1 to 17)

[0202] As shown in Tables 2 to 14, the same procedures as in Examples 1 to 15 were carried out except that the compound (C) was changed to a compound containing a functional group other than carbamate or was not added. Ic ) as shown in Tables 2 to 14.

[0203] [Table 1]

[0204]

[0205] [Table 2]

[0206]

[0207] [Table 3]

[0208]

[0209] [Table 4]

[0210]

[0211] [Table 5]

[0212]

[0213] [Table 6]

[0214]

[0215] [Table 7]

[0216]

[0217] [Table 8]

[0218]

[0219] [Table 9]

[0220]

[0221] [Table 10]

[0222]

[0223] [Table 11]

[0224]

[0225] [Table 12]

[0226]

[0227] [Table 13]

[0228]

[0229] [Table 14]

[0230]

Claims

1. A urethane resin-forming composition comprising: A curing agent containing polyol (A), Isocyanate group-terminated prepolymer (B), and Compound (C), The compound (C) is a compound represented by formula (1): R 1 -NHCOO-R 2 (1) Where R 1 and R 2 Each is independently an alkyl group, an alicyclic hydrocarbon group, an aryl group or a heterocyclic group.

2. The composition according to claim 1, wherein The curing agent (A) contains a crosslinking component (a-1).

3. The composition according to claim 1, wherein The curing agent (A) contains at least one diol (a-2) selected from the group consisting of aliphatic diols and alicyclic diols.

4. The composition according to claim 1, wherein The curing agent (A) comprises a crosslinking component (a-1), and At least one diol (a-2) selected from the group consisting of aliphatic diols and alicyclic diols.

5. The composition according to claim 1, wherein The isocyanate group-terminated prepolymer (B) comprises a reaction product of a polyol (b-1) having a number average molecular weight of 500 or more, a polyisocyanate (b-2), and an optional crosslinking component (b-3).

6. The composition according to claim 1, wherein The curing agent (A) comprises a crosslinking component (a-1) and at least one diol (a-2) selected from the group consisting of aliphatic diols and alicyclic diols. The isocyanate group-terminated prepolymer (B) comprises a reaction product of a polyol (b-1) having a number average molecular weight of 500 or more, a polyisocyanate (b-2), and an optional crosslinking component (b-3).

7. The composition according to claim 1, wherein The isocyanate-terminated prepolymer (B) comprises a reaction product of a polyol (b-1) having a number average molecular weight of 500 or more, a polyisocyanate (b-2), and an optional crosslinking component (b-3). The polyol (b-1) has a carbonate bond.

8. The composition according to claim 1, wherein The curing agent (A) comprises a crosslinking component (a-1) and at least one diol (a-2) selected from the group consisting of aliphatic diols and alicyclic diols. The isocyanate-terminated prepolymer (B) comprises a reaction product of a polyol (b-1) having a number average molecular weight of 500 or more, a polyisocyanate (b-2), and an optional crosslinking component (b-3). The polyol (b-1) has a carbonate bond.

9. The composition according to any one of claims 1 to 8, wherein The urethane group concentration of the resin obtained by curing the urethane resin-forming composition is 2000 mmol / kg or more and 5500 mmol / kg or less.

10. The composition according to any one of claims 1 to 8, wherein The total content of the crosslinkable group of the curing agent (A) and the content of the crosslinkable group of the isocyanate group-terminated prepolymer (B) in the urethane resin-forming composition is 50 mmol / kg or more and 1000 mmol / kg or less.

11. The composition according to any one of claims 1 to 8, wherein The melting point of the compound (C) is 100° C. or lower. 12 . A composition for a urethane adhesive, comprising the urethane resin-forming composition according to claim 1 .

13. The composition according to claim 12, wherein The content of the solvent is 1.0% by mass or less.

14. An adhesive for automobile structures, comprising the composition according to claim 12. 15 . A cured product, which is a cured product of the composition according to claim 1 .

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