Polyurethane adhesive compositions, automotive structural adhesives, and cured products

Abstract

To provide a composition for a polyurethane adhesive, an adhesive for an automobile structure and a cured product of a composition for a polyurethane adhesive, which exhibit a high fracture toughness value.SOLUTION: There is provided a composition for a polyurethane adhesive which comprises a curing agent (A) and an isocyanate group terminal prepolymer (B), wherein the curing agent (A) contains a transesterification product (a-1) obtained by subjecting an aromatic diol (a-1-1) and a polyol (a-1-2) to transesterification and an optional crosslinking agent (a-2), the polyol (a-1-2) is a polyol containing one or more bonds selected from the group consisting of an ester bond and a carbonate bond, the isocyanate group terminal prepolymer (B) is a reaction product of a polyol (b-1) having an average molecular weight of 2500 or more, a polyisocyanate (b-2) and an optional crosslinking agent (b-3) and contains at least one of the crosslinking agent (a-2) and the crosslinking agent (b-3).SELECTED DRAWING: None

Description

Technical Field

[0001] The present disclosure relates to a composition for a polyurethane adhesive, an adhesive for automobile structures, and a cured product.

Background Art

[0002] Automobile structure adhesives have various required properties. Among them, the physical property that has attracted particular attention is the fracture toughness value. The fracture toughness value is considered as a composite index of flexibility and rigidity and is expressed in units of energy. A larger fracture toughness value means better resistance when energy is applied to the adhesive (such as impact), so a larger value is more preferable. Patent Document 1 discloses a first liquid containing a prepolymer obtained by reacting a polyisocyanate with a polyol having a specific molecular weight and a filler having a specific blending amount, and a second liquid containing a polyol having a specific molecular weight and a catalyst, and a urethane-based adhesive composition in which the number of moles of hydroxyl groups derived from the polyol in the first liquid and the polyol in the second liquid have a specific relationship. According to Patent Document 1, such a urethane-based adhesive composition can obtain good adhesive performance and also has excellent storage stability.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in Patent Document 1, although the tensile shear strength is measured as the adhesive performance, the fracture toughness value is not sufficient, and there is a need for an adhesive composition in which flexibility and rigidity are highly compatible.

[0005] Therefore, one aspect of this disclosure is directed towards providing a polyurethane adhesive composition exhibiting high fracture toughness, an adhesive for automotive structures, and a cured product of a polyurethane adhesive composition. [Means for solving the problem]

[0006] Each aspect of this disclosure provides the embodiments shown in (1) to (9) below. (1): Hardener (A), The material comprises an isocyanate group-terminated prepolymer (B), The aforementioned hardening agent (A) is A transesterified product (a-1) obtained by transesterifying an aromatic diol (a-1-1) and a polyol (a-1-2), It contains an optional crosslinking agent (a-2), The polyol (a-1-2) is a polyol containing one or more bonds selected from the group consisting of ester bonds and carbonate bonds. The isocyanate-terminated prepolymer (B) is Polyols with a number-average molecular weight of 2500 or more (b-1), Polyisocyanate (b-2) and, The reaction product of the optional component, the crosslinking agent (b-3), A polyurethane resin-forming composition comprising at least one of the crosslinking agent (a-2) and the crosslinking agent (b-3). (2): The polyurethane resin-forming composition according to (1), wherein the polyol (a-1-2) is a polycarbonate polyol. (3) The polyurethane adhesive composition according to (1) or (2), wherein the urethane group concentration of the resin obtained by curing the polyurethane resin-forming composition is 2000 mmol / kg or more and 4500 mmol / kg or less. (4): A polyurethane adhesive composition according to any one of items (1) to (3), wherein the solvent content is 1.0% by mass or less. (5): A polyurethane adhesive composition according to any one of (1) to (4), further comprising filler (C). (6): The polyurethane adhesive composition according to any one of (1) to (5), wherein at least one of the curing agent (A) and the isocyanate group-terminated prepolymer (B) is liquid at 25°C and 1 atm. (7): A polyurethane adhesive composition according to any one of (1) to (6), which is liquid at 25°C and 1 atm. (8): An automotive structural adhesive comprising a polyurethane adhesive composition as described in any one of items (1) to (7). (9): A cured product of a polyurethane adhesive composition described in any one of items (1) to (7). [Effects of the Invention]

[0007] According to one aspect of this disclosure, it is possible to provide a polyurethane adhesive composition exhibiting high fracture toughness, an adhesive for automotive structures, and a cured product of a polyurethane adhesive composition. [Modes for carrying out the invention]

[0008] The following describes in detail exemplary embodiments for carrying out each aspect of this disclosure.

[0009] [Polyurethane adhesive composition] A polyurethane adhesive composition according to one aspect of this disclosure, Hardener (A), The material comprises an isocyanate group-terminated prepolymer (B), The aforementioned hardening agent (A) is A transesterified product (a-1) obtained by transesterifying an aromatic diol (a-1-1) and a polyol (a-1-2), It contains an optional crosslinking agent (a-2), The polyol (a-1-2) is a polyol containing one or more bonds selected from the group consisting of ester bonds and carbonate bonds. The isocyanate-terminated prepolymer (B) is Polyols with a number-average molecular weight of 2500 or more (b-1), The reaction product of polyisocyanate (b-2) and crosslinking agent (b-3) which is an optional component, and contains at least one of the crosslinking agent (a-2) and the crosslinking agent (b-3).

[0010] [[Polyurethane resin-forming composition]] The polyurethane resin-forming composition contains curing agent (A) and isocyanate group-terminated prepolymer (B).

[0011] [[[Curing agent (A)]]] The curing agent (A) contains transesterified product (a-1) obtained by transesterification of aromatic diol (a-1-1) and polyol (a-1-2) and crosslinking agent (a-2) which is an optional component. Examples of the polyol (a-1-2) include polyols containing one or more bonds selected from the group consisting of ester bonds and carbonate bonds. In other words, the transesterified product (a-1) has a site derived from aromatic diol (a-1-1) and a site derived from polyol (a-1-2), and the site derived from the polyol (a-1-2) has one or more bonds selected from the group consisting of ester bonds and carbonate bonds.

[0012] Examples of the aromatic diol (a-1-1) include bisphenol A, bis(4-hydroxy-3-methylphenyl)sulfide, 1,3-bis[2-(4-hydroxyphenyl)-2-propyl]benzene, bis[3,5-dibromo-4-(2-hydroxyethoxy)phenyl]sulfone, 4,4'-bis(hydroxymethyl)biphenyl, bis[4-(2-hydroxyethoxy)phenyl]sulfone, 2,2'-bis(hydroxymethyl)diphenyl ether, 1,4-benzenedimethanol, 1,4-benzenediethanol, 1,4-bis(β-hydroxyethoxy)benzene; etc.

[0013] Polyol (a-1-2) is preferably polyester polyol or polycarbonate polyol, with polycarbonate polyol being more preferred.

[0014] Examples of polycarbonate polyols include ethylene glycol, 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-dimethylolheptane, diethylene glycol, dipropylene glycol, neopentyl glycol, cyclohexane-1,4-diol, cyclohexane-1,4-dimethanol, glycerin, trimethylolpropane, and dimethylol. Examples include those obtained from de-alcoholization or de-phenolization reactions of one or more polyols such as acid diols, ethylene oxide or propylene oxide adducts of bisphenol A, bis(β-hydroxyethyl)benzene, and xylylene glycol; and one or more dialkyl carbonates such as dimethyl carbonate and diethyl carbonate, alkylene carbonates such as ethylene carbonate and propylene carbonate, and carbonates such as diphenyl carbonate, dinaphthyl carbonate, diantryl carbonate, diphenanthryl carbonate, and diindanyl carbonate.

[0015] Examples of polyester polyols include one or more dicarboxylic acids such as phthalic acid, isophthalic acid, terephthalic acid, naphthalenedicarboxylic 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-cyclohexyldicarboxylic acid, α-hydromuconic acid, β-hydromuconic acid, α-butyl-α-ethylglutaric acid, α,β-diethylsuccinic acid, maleic acid, fumaric acid, or their anhydrides; and ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4 Examples include polyols obtained by condensation polymerization reactions with one or more of the following: -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, glycerin, trimethylolpropane, dimer acid diol, ethylene oxide or propylene oxide adducts of bisphenol A, bis(β-hydroxyethyl)benzene, xylylene glycol, etc. Furthermore, as polyols (a-1-2), polyester-amide polyols obtained by replacing some of these alcohols with low molecular weight polyamines or low molecular weight amino alcohols such as hexamethylenediamine, isophoronediamine, and monoethanolamine are also examples.

[0016] Polyol (a-1-2) may contain only one of these types, or it may contain two or more types.

[0017] The polyol (a-1-2) preferably has a number-average molecular weight of less than 1000 g / mol, and more preferably 750 g / mol or less.

[0018] In this disclosure, the number-average molecular weight can be any value obtained by a highly accurate measurement method; for example, a value measured by a method compliant with JIS K 0070-1992 (titration method) can be used.

[0019] The hardening agent (A) contains a transesterified product (a-1), which improves the fracture toughness value (G 1c A polyurethane adhesive composition with high fracture toughness and excellent toughness can be obtained. Fracture toughness is considered a combined index of flexibility and stiffness and is expressed in units of energy. A higher fracture toughness value means that the adhesive has better resistance when energy is applied to it (such as impact), so a higher fracture toughness value is preferable.

[0020] The curing agent (A) contains an optional crosslinking component (a-2). That is, the curing agent (A) may further contain the crosslinking component (a-2). Examples of crosslinking components (a-2) include polyols with an average number of 3 or more functional groups. Examples of polyols with an average number of 3 or more functional groups include glycerin, trimethylolpropane, pentaerythritol, N,N-bishydroxypropyl-N-hydroxyethylamine, triethanolamine, triisopropanolamine, monomer polyols modified from ethylenediamine propylene oxide, monomer polyols modified from trimethylolpropane propylene oxide, and modified from pentaerythritol propylene oxide. In addition to these, polycaprolactone polyols can be 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.

[0021] The cross-linking component (a-2) may contain only one of these types, or it may contain two or more types.

[0022] The curing agent (A) is preferably liquid at 25°C and 1 atmosphere.

[0023] The curing agent (A) may contain active hydrogen-containing compounds in addition to polyols. Examples of such active hydrogen-containing compounds include compounds having functional groups such as amino groups, thiol groups, and carboxyl groups. These active hydrogen-containing compounds can be used individually or in combination of two or more.

[0024] [[[Isocyanate-terminated prepolymer (B)]]] The isocyanate-terminated prepolymer (B) is Polyols with a number-average molecular weight of 2500 or more (b-1), This is the reaction product of polyisocyanate (b-2) and [another substance].

[0025] Examples of polyols (b-1) with a number average molecular weight of 2500 or more include those similar to polyol (a-1-2) and with a number average molecular weight of 2500 or more.

[0026] The number-average molecular weight of polyol (b-1) is preferably between 2500 and 10000, and more preferably between 2500 and 7000.

[0027] Examples of polyisocyanates (b-2) include polyisocyanates having two or more isocyanate groups in the molecule. Organic polyisocyanates can be used as the polyisocyanate, and examples of organic polyisocyanates include aromatic polyisocyanates, aromatic aliphatic polyisocyanates, aliphatic polyisocyanates, and alicyclic polyisocyanates. These can be used individually or in combination of two or more. Among these, aromatic polyisocyanates are preferred from the viewpoint of reactivity and viscosity.

[0028] Examples of aromatic polyisocyanates include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 2,4-tolylene diisocyanate / 2,6-tolylene diisocyanate mixture, 2,2'-diphenylmethane diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,2'-diphenylmethane diisocyanate / 4,4'-diphenylmethane diisocyanate mixture, 2,4'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate / 4,4'-diphenylmethane diisocyanate mixture, 2,2'-diphenylmethane diisocyanate / 2,4'-diphenylmethane diisocyanate / Examples include 4,4'-diphenylmethane diisocyanate mixtures, m-xylylene diisocyanate, p-xylylene diisocyanate, 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, and 3,3'-dimethoxydiphenyl-4,4'-diisocyanate.

[0029] Examples of aromatic aliphatic polyisocyanates include 1,3-xylylene diisocyanate, 1,4-xylylene diisocyanate, a mixture of 1,3-xylylene diisocyanate and 1,4-xylylene diisocyanate, 1,3-bis(1-isocyanato-1-methylethyl)benzene, 1,4-bis(1-isocyanato-1-methylethyl)benzene, a mixture of 1,3-bis(1-isocyanato-1-methylethyl)benzene and 1,4-bis(1-isocyanato-1-methylethyl)benzene, and ω,ω'-diisocyanato-1,4-diethylbenzene.

[0030] Examples of aliphatic polyisocyanates 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, and 2,4,4-trimethylhexamethylene diisocyanate. Examples include ethylene diisocyanate, 1,6,11-undecane triisocyanate, 1,3,6-hexamethylene triisocyanate, 1,8-diisocyanate-4-isocyanate methyl octane, 2,5,7-trimethyl-1,8-diisocyanate-5-isocyanate methyl octane, bis(isocyanate ethyl) carbonate, bis(isocyanate ethyl) ether, 1,4-butylene glycol dipropyl ether-α,α'-diisocyanate, lysine diisocyanate methyl ester, 2-isocyanate ethyl-2,6-diisocyanate hexanoate, and 2-isocyanate propyl-2,6-diisocyanate hexanoate.

[0031] Examples of alicyclic polyisocyanates include isophorone diisocyanate, cyclohexane diisocyanate, bis(isocyanate-methyl)cyclohexane, dicyclohexylmethane diisocyanate, methylcyclohexane diisocyanate, dicyclohexyldimethylmethane diisocyanate, 2,2'-dimethyldicyclohexylmethane diisocyanate, bis(4-isocyanate-n-butylidene)pentaerythritol, hydrogenated hydrogenated dimer acid diisocyanate, 2-Isocyanatemethyl-3-(3-isocyanatetopropyl)-5-isocyanatemethyl-bicyclo[2.2.1]-heptane, 2-Isocyanatemethyl-3-(3-isocyanatetopropyl)-6-isocyanatemethyl-bicyclo[2.2.1]-heptane, 2-Isocyanatemethyl-2-(3-isocyanatetopropyl)-5-isocyanatemethyl-bicyclo[2.2.1]-heptane, 2-Isocyanatemethyl-2-(3-isocyanatetopropyl)-6-isocyanate Nate-methyl-bicyclo[2.2.1]-heptane, 2-isocyanate-methyl-3-(3-isocyanatetopropyl)-5-(2-isocyanatetoethyl)-bicyclo-[2.2.1]-heptane, 2-isocyanate-methyl-3-(3-isocyanatetopropyl)-6-(2-isocyanatetoethyl)-bicyclo-[2.2.1]-heptane, 2-isocyanate-methyl-2-(3-isocyanatetopropyl)-5-(2-isocyanatetoethyl)-bicyclo-[2.2.1]-heptane Examples include 2-isocyanatemethyl-2-(3-isocyanatetopropyl)-6-(2-isocyanateethyl)-bicyclo-[2.2.1]-heptane, 2,5-bis(isocyanatemethyl)-bicyclo[2.2.1]-heptane, hydrogenated hydrogenated diphenylmethane diisocyanate, norbornane diisocyanate, hydrogenated hydrogenated tolylene diisocyanate, hydrogenated hydrogenated xylene diisocyanate, and hydrogenated hydrogenated tetramethylxylene diisocyanate.

[0032] Polyisocyanates (b-2) can be used individually or in combination of two or more of these.

[0033] The isocyanate-terminated prepolymer (B) contains an optional crosslinking agent (b-3). In other words, the isocyanate-terminated prepolymer (B) is Polyols with a number-average molecular weight of 2500 or more (b-1), Polyisocyanate (b-2) and, It may also be a reaction product with an optional crosslinking component (b-3). Examples of crosslinking components (b-3) include those similar to those of crosslinking component (a-2).

[0034] Here, the crosslinking component may be contained in the polyurethane adhesive composition in either of the following embodiments (1) and (2), or in an embodiment corresponding to both (1) and (2). (1) The hardening agent (A) further contains a crosslinking component (a-2). (2) The isocyanate group-terminated prepolymer (B) Polyols with a number-average molecular weight of 2500 or more (b-1), Polyisocyanate (b-2) and, This is the reaction product of the crosslinking component (b-3).

[0035] Here, a crosslinking group is a functional group that forms a crosslink. Therefore, taking a trifunctional polyol (for example, glycerin) as an example, one hydroxyl group in one molecule forms a crosslink, while the remaining two hydroxyl groups do not contribute to crosslinking. In this case, there is one crosslinkable group. In other words, in the case of a trifunctional polyol, the crosslinkable group content is synonymous with the content of the trifunctional polyol, since the trifunctional polyol has one crosslinkable group.

[0036] The isocyanate-terminated prepolymer (B) Polyether polyol (b-1) and, Polyisocyanate (b-2) and, It is more preferable that the crosslinking component (b-3) is a reaction product of .

[0037] The isocyanate-terminated prepolymer (B) may contain other components. Preferably, these other components do not react with the functional groups of the isocyanate-terminated prepolymer (B) and the curing agent (A) described later (e.g., fillers, colorants, antistatic agents, preservatives).

[0038] Preferably, at least one of the polyol (b-1) and polyisocyanate (b-2) is liquid at 25°C and 1 atm.

[0039] It is preferable that at least one of the curing agent (A) and the isocyanate group-terminated prepolymer (B) is liquid at 25°C and 1 atm.

[0040] The curing agent (A) and the isocyanate-terminated prepolymer (B) may contain other components. Preferably, the other components are those that do not react with the curing agent (A) and the isocyanate-terminated prepolymer (B) when mixed (e.g., fillers, colorants, antistatic agents, preservatives).

[0041] The urethane group concentration of the resin obtained by curing the polyurethane resin-forming composition is preferably 2000 mmol / kg or more and 4500 mmol / kg or less, and more preferably 3000 mmol / kg or more and 4000 mmol / kg or less. If the urethane group concentration of the resulting resin is within this range, the fracture toughness value (G1c) becomes even higher, resulting in superior toughness, which is therefore even more preferable.

[0042] From the viewpoint of handling, polyurethane adhesive compositions are preferably liquid (i.e., fluid) at 25°C and 1 atm.

[0043] [[[Filler (C)]]] The polyurethane adhesive composition preferably further contains a filler (C). Examples of filler (C) include known fillers, such as inorganic fillers and organic fillers. Among these, inorganic fillers are preferred.

[0044] Examples of inorganic fillers include, but are not limited to, talc, zeolite, silica, microballoons, clay, glass balloons, carbon black, and calcium carbonate. These can be used individually or in combination of two or more.

[0045] Examples of organic fillers include polyamide particles, acrylic particles, carbon nanotubes, starch, natural organic fibers, and synthetic fibers.

[0046] The filler content is preferably 10% by mass or more and 70% by mass or less, and more preferably 10% by mass or more and 50% by mass or less, based on the total mass of the polyurethane adhesive composition. A filler content of 10% by mass or more can better suppress dripping. A filler content of 70% by mass or less allows the filler and other components to mix more uniformly, resulting in even better adhesive strength and coating properties.

[0047] The polyurethane adhesive composition comprises a curing agent (A) and an isocyanate-terminated prepolymer (B). These may be a two-component type, existing separately, or a one-component type, where they are mixed together. The temperature and time for mixing the curing agent (A) and the isocyanate-terminated prepolymer (B) can be, for example, 10 to 35°C for 1 to 60 minutes.

[0048] The method for mixing the curing agent (A) and the isocyanate group-terminated prepolymer (B) is not particularly limited. For example, the mixture may be mixed manually with a spatula, or it may be mixed using a mechanical rotary mixer, a static mixer, or the like.

[0049] The polyurethane adhesive composition preferably has a solvent content of 1.0% by mass or less. Furthermore, polyurethane adhesive compositions may be substantially solvent-free, i.e., solvent-free. However, if a solvent is present as an impurity, it falls under the category of being substantially solvent-free.

[0050] [Automotive structural adhesive] An automotive structural adhesive according to one aspect of this disclosure includes the polyurethane adhesive composition described above.

[0051] [Cured product] A cured product according to one aspect of this disclosure is a cured product of the polyurethane adhesive composition described above. [Examples]

[0052] The present invention will be described in more detail below based on examples, but the present invention is not limited to the following examples.

[0053] [Preparation of urethane resin-forming compositions] The following compounds were mixed in the amounts listed in Tables 1 and 2 to prepare polyurethane adhesive compositions. Note that "f" represents the number of functional groups. [Raw materials] • "MT"; Millionate® MT (Monomeric MDI, manufactured by Tosoh Corporation) Average molecular weight 250, f=2 • "TMP"; Trimethylolpropane (manufactured by Mitsubishi Gas Chemical Company) Trimethylolpropane, average molecular weight 134, f=3 • "PTG-L3500"; Amorphous polytetramethylene ether glycol (Manufactured by Hodogaya Chemical Co., Ltd.) Average molecular weight 3500, f=2 • "PCD500"; polycarbonate polyol, KurarayPolyol C-590 (manufactured by Kuraray Co., Ltd.) Average molecular weight 500, f=2 • "N-969"; Polycarbonate polyol (Manufactured by Tosoh Corporation, Nipponran (registered trademark) 969) Average molecular weight 3000, f=2 • "N-968"; Polycarbonate polyol (Manufactured by Tosoh Corporation, Nipponran (registered trademark) 968) Average molecular weight 3000, f=2 • "BG"; Butylene glycol (manufactured by Mitsubishi Chemical Corporation) 1,4-Butanediol, average molecular weight 90, f=2 • "BHEB"; 1,4-bis(β-hydroxyethoxy)benzene (manufactured by Tokyo Chemical Industry Co., Ltd.) • "CHDM"; 1,4-Cyclohexanedimethanol (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) • "p-TolylDEA"; 2,2'-(p-tolylimino)diethanol (manufactured by Tokyo Chemical Industry Co., Ltd.) • "Zeolite"; Zeoram (registered trademark) A-3 (manufactured by Tosoh Corporation) • "Talc"; Talc (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.)

[0054] (Examples 1-2) Each ingredient of the curing agent was added to a 2L stirring container according to the formulation shown in Table 1 and stirred. The mixture was then mixed and stirred for about 5-6 hours while maintaining the temperature inside the stirring container at 180°C to obtain the curing agent ingredient, transesterified diol (average molecular weight 500).

[0055] Each of the hardening agent ingredients was added to a 2L stirring container filled with nitrogen according to the formulation shown in Table 2 and stirred. The mixture was then mixed and stirred for 1 to 3 hours while maintaining the temperature inside the stirring container at 70 to 80°C to obtain various hardening agents (A).

[0056] Furthermore, each raw material for the main component (isocyanate-terminated prepolymer) (B) was added to a 2L stirring vessel filled with nitrogen according to the formulation shown in Table 2, and stirred. Then, while maintaining the temperature inside the stirring vessel at 70-80°C, the urethane reaction was carried out for about 2-5 hours to obtain various isocyanate-terminated prepolymers (B).

[0057] [DCB Test (Fracture Toughness Value)] The DCB trial was conducted in accordance with ASTM D3433-99. The resin thickness was adjusted to 0.35mm using spacers. Spacers use Teflon® tape. Specimen shape: Contoured type used Test substrate: S50C steel (electroless nickel plating treatment) was used. Test conditions: Tensile load was applied at 2 mm / min, and the fracture toughness value G1c was calculated based on the maximum load. Calculation formula: G 1c =[4L 2 (max)](m) / [EB 2 ] L(max) Load:(N) E. Young's modulus of the substrate (MPa): 208000 B. Width of base material (mm): 25.49 m constant (from contoured type): 3.54

[0058] The filler (C) (50% by mass of talc / 50% by mass of zeolite) was added to the main component (isocyanate group-terminated prepolymer) (B) and mixed and degassed so that the amount of filler in the system was 1 / 3. After stirring and mixing for 30 seconds, the mixture was applied to the substrate and secured with clamps. Then, it was cured by a two-stage heat treatment at 130°C for 1.5 hours and 110°C for 20 hours. To create a pre-crack in the substrate, a 0.35 mm thick Teflon® seal was applied 4.9 cm from the leading edge. Additionally, to ensure a uniform adhesive application thickness, a Teflon® seal of the same thickness was applied approximately 2 cm from the rear of the substrate. Table 2 shows the fracture toughness values ​​(G1c) obtained from DCB tests conducted under the above conditions.

[0059] [Agglomeration rate] The fracture surface of the sample was visually observed, and the percentage of the area fractured by the adhesive layer was measured. The measurement results are shown in Table 2. Cohesive failure: A condition in which the resin layer is broken. Interfacial fracture: A condition where the resin peels off at the substrate interface.

[0060] Table 1

[0061] Table 2

Claims

1. Hardener (A), The material comprises an isocyanate-terminated prepolymer (B), The hardening agent (A) is A transesterified product (a-1) obtained by transesterifying an aromatic diol (a-1-1) with a polycarbonate polyol, It contains an optional crosslinking agent (a-2), The isocyanate-terminated prepolymer (B) is Polyols with a number average molecular weight of 2500 or more (b-1), Polyisocyanate (b-2) and, The reaction product of a crosslinking agent (b-3), which is an optional component, and a component containing the above. A composition for polyurethane adhesives comprising at least one of the crosslinking agent (a-2) and the crosslinking agent (b-3).

2. A hardening agent (A), The material comprises an isocyanate-terminated prepolymer (B), The hardening agent (A) is A transesterified product (a-1) obtained by transesterifying an aromatic diol (a-1-1) with a polycarbonate polyol, It contains an optional crosslinking agent (a-2), The aromatic diol (a-1-1) includes bisphenol A, bis(4-hydroxy-3-methylphenyl) sulfide, 1,3-bis[2-(4-hydroxyphenyl)-2-propyl]benzene, bis[3,5-dibromo-4-(2-hydroxyethoxy)phenyl]sulfone, 4,4'-bis(hydroxymethyl)biphenyl, bis[4-(2-hydroxyethoxy)phenyl]sulfone, 2,2'-bis(hydroxymethyl)diphenyl ether, 1,4-benzenedimethanol, 1,4-benzenediethanol, or 1,4-bis(β-hydroxyethoxy)benzene. The isocyanate-terminated prepolymer (B) is Polyols with a number average molecular weight of 2500 or more (b-1), Polyisocyanate (b-2) and, The reaction product of a crosslinking agent (b-3), which is an optional component, and a component containing the above. A polyurethane resin-forming composition comprising at least one of the crosslinking agent (a-2) and the crosslinking agent (b-3).

3. The polyurethane adhesive composition or polyurethane resin-forming composition according to claim 1 or 2, wherein the urethane group concentration of the resin obtained by curing the polyurethane adhesive composition or the polyurethane resin-forming composition is 2000 mmol / kg or more and 4500 mmol / kg or less.

4. A polyurethane adhesive composition or polyurethane resin-forming composition according to any one of claims 1 to 3, wherein the solvent content is 1.0% by mass or less.

5. Furthermore, the polyurethane adhesive composition or polyurethane resin-forming composition according to any one of claims 1 to 4, comprising a filler (C).

6. The isocyanate group-terminated prepolymer (B) Polyols with a number average molecular weight of 2500 or more (b-1), Polyisocyanate (b-2) and, The optional component is a crosslinking agent (b-3), A polyurethane adhesive composition or polyurethane resin-forming composition according to any one of claims 1 to 5, which is a reaction product of a component containing a polycarbonate polyol.

7. An automotive structural adhesive comprising a polyurethane adhesive composition or a polyurethane resin-forming composition according to any one of claims 1 to 6.

8. A cured product of a polyurethane adhesive composition or polyurethane resin-forming composition according to any one of claims 1 to 6.

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