Curing resin composition, cured product

Abstract

This invention provides a solvent-free curable resin composition that combines high adhesion (heat-resistant adhesion) under high-temperature conditions with excellent adhesion, flexibility, and impact resistance, making it particularly suitable for structural bonding fields and matrix resin applications where high reliability is required. [Solution] A curable resin composition comprising a curing agent (X) containing a polyurethane urea resin (A) having a primary or secondary amino group at its terminus and a liquid polyamine (B) having a cyclic structure, and a main component (Y) containing a liquid epoxy resin (C) having a cyclic structure, wherein the liquid polyamine (B) has a primary or secondary amino group, and the polyurethane urea resin (A) is present in an amount of 20 to 70% by mass of the total of 100% by mass of the organic components having primary amino groups and organic components having secondary amino groups contained in the curing agent (X).

Description

Technical Field

[0001] The present invention relates to a curable resin composition and a cured product thereof.

Background Art

[0002] Epoxy resin compositions are widely used in various fields where reliability is required, such as structural adhesives, sealants, and matrix resins for vehicle bodies and automotive parts, etc., because they are excellent in heat resistance, adhesion, mechanical strength, electrical properties, and processability.

[0003] On the other hand, since the cured product of epoxy resin is generally poor in flexibility and brittle, various modifications have been made to improve flexibility and impact resistance without degrading the original excellent properties of epoxy resin such as heat resistance and mechanical strength.

[0004] For example, as components for enhancing flexibility and impact resistance, core-shell type rubber particles, polymer epoxy resins such as polybutadiene with epoxy group terminals, polyurethane, and polyester have been studied.

[0005] In Patent Document 1, it is disclosed that by using core-shell type rubber particles as a modifier for epoxy resin, a high glass transition temperature and flexibility can be obtained. However, although flexibility and toughness are improved by the addition of rubber particles, there are still problems in impact resistance, such as easy fracture at the substrate interface when a strong impact is applied to the substrate bonding site.

[0006] Also, as in Patent Document 2, softening using a polymer epoxy resin has been studied, but a large amount of resin needs to be added to obtain flexibility. In that case, there are problems such as a significant decrease in heat resistance and a decrease in workability due to an increase in viscosity.

[0007] On the other hand, in recent years, from the perspective of global environmental protection, a lower temperature in the thermosetting process has been required to reduce carbon dioxide emissions and energy costs.

[0008] To address these challenges, two-component curable resin compositions using amine compounds as curing agents for epoxy resins offer excellent workability due to their storage stability and gentle curing at room temperature. Furthermore, they can be cured at relatively low temperatures (below 130°C) and in a short time, making them suitable as environmentally friendly materials.

[0009] For example, Patent Documents 3 and 4 disclose that using cyclic aliphatic amines and polyetheramines as curing agents can achieve both a high glass transition temperature and flexibility. However, the elongation rate is still only about 5-7%, which is somewhat insufficient in terms of flexibility, and further improvements are needed in terms of impact resistance.

[0010] On the other hand, Patent Document 5 discloses that high flexibility can be obtained by using an amino-terminated urethane urea, whose chain is extended with a diamine having an ether group, as a modifier. However, its heat resistance is insufficient, and various combinations are still being investigated to satisfy high heat resistance, flexibility, and impact resistance. [Prior art documents] [Patent Documents]

[0011] [Patent Document 1] Patent Application No. 2020-554919 [Patent Document 2] Patent Application No. 2020-510649 [Patent Document 3] Special Publication No. 2017-538002 [Patent Document 4] Special Publication No. 2018-502172 [Patent Document 5] Special Publication No. 2013-521361 [Overview of the project] [Problems that the invention aims to solve]

[0012] The object of the present invention is to provide a solvent-free curable resin composition that combines high adhesion (heat-resistant adhesion) under high-temperature conditions, flexibility, and impact resistance, and is particularly suitable for structural bonding fields and matrix resin applications where high reliability is required. [Means for solving the problem]

[0013] As a result of diligent research to solve the above problems, the inventors of the present invention have found that the problems of the present invention can be solved in the following embodiment, and have completed the present invention.

[0014] The present invention relates to a solvent-free curable resin composition comprising a curing agent (X) containing a polyurethane urea resin (A) and a liquid polyamine (B), and a main component (Y) containing a liquid epoxy resin (C), and characterized by satisfying all of the following conditions (i) to (iv). (i) Polyurethane urea resin (A) has a primary or secondary amino group at its terminus. (ii) The liquid polyamine (B) has a cyclic structure and contains a primary amino group or a secondary amino group. (iii) The curing agent (X) contains 20 to 70% by mass of polyurethane urea resin (A) in a total of 100% by mass of the organic component having a primary amino group and the organic component having a secondary amino group. (iv) The glass transition temperature of the cured product made from the curable resin composition is 100°C or higher.

[0015] Furthermore, the present invention relates to the curable resin composition wherein the number average molecular weight of the liquid polyamine (B) is 350.

[0016] Furthermore, the present invention relates to the curable resin composition wherein the number average molecular weight of the polyurethane urea resin (A) is 1,000 or more and less than 50,000.

[0017] Furthermore, the present invention relates to a curable resin composition containing 2.1 to 5.8 mmol / g of cyclic structures in the total amount of the polyurethane urea resin (A) and the liquid polyamine (B).

[0018] The present invention also relates to a cured product comprising the curable resin composition. [Effects of the Invention]

[0019] According to the present invention, a curable resin composition particularly suitable for structural bonding fields and matrix resin applications that require high reliability, having high adhesion (heat-resistant adhesion), flexibility, and impact resistance under high-temperature conditions can be provided. [Modes for Carrying Out the Invention]

[0020] Hereinafter, the present invention will be described in detail. As long as it conforms to the gist of the present invention, other embodiments are also included in the scope of the present invention. In addition, the numerical range specified using "~" in this specification includes the numerical values described before and after "~" as the range of the lower limit value and the upper limit value. In addition, various components appearing in this specification may be used alone or in combination of two or more, respectively, unless otherwise noted.

[0021] In this specification, the curing agent refers to the curing agent in a two-component curable resin composition, and the main agent refers to the main agent in a two-component curable resin composition. In this specification, solvent-free means that there is no intentional addition of a volatile organic solvent, and the content of the volatile organic solvent not involved in the curing reaction in the curable resin composition is less than 3% by mass.

[0022] The solvent-free curable resin composition in the present invention contains a curing agent (X) containing a polyurethane-urea resin (A) having a primary amino group or a secondary amino group at the terminal and a liquid polyamine (B) having a cyclic structure, and a main agent (Y) containing a liquid epoxy resin (C), and is characterized by satisfying all of the following (i) to (iv). (i) The polyurethane-urea resin (A) has a primary amino group or a secondary amino group at the terminal. (ii) The liquid polyamine (B) has a cyclic structure and has a primary amino group or a secondary amino group. (iii) The curing agent (X) contains 20 to 70% by mass of polyurethane urea resin (A) in a total of 100% by mass of the organic component having a primary amino group and the organic component having a secondary amino group. (iv) The glass transition temperature of the cured product made from the curable resin composition is 100°C or higher.

[0023] By satisfying all of the above conditions, the curing agent (X) forms an appropriate phase separation structure when it crosslinks with the main component (Y), exhibiting excellent flexibility while maintaining high adhesion (heat-resistant adhesion) under high-temperature conditions. Furthermore, the cured film obtained in this way has extremely high impact resistance. Therefore, the curable resin composition of the present invention is suitably used as a structural adhesive or matrix resin in fields where high reliability is required. In addition, the curable resin composition of the present invention can be used as a liquid solvent-free adhesive, and is excellent from the viewpoint of safety and environmental friendliness.

[0024] [Hardening agent (X)] The curing agent (X) contains a polyurethane urea resin (A) having a primary or secondary amino group at its terminus, and a liquid polyamine (B) having a cyclic structure and having a primary or secondary amino group. The curing agent (X) is not limited to the polyurethane urea resin (A) and the liquid polyamine (B), but may also include other amine curing agents, curing accelerators, and additives that contribute to the crosslinking reaction with the epoxy resin (C) in the main component (Y), as needed.

[0025] Polyurethane urea resin (A) Polyurethane urea resin (A) has a primary or secondary amino group at its terminus. Polyurethane urea resin (A) is obtained by reacting a polyol, a polyisocyanate, and a polyamine such that amino groups remain in the polyamine.

[0026] The number-average molecular weight of the polyurethane urea resin (A) is not particularly limited, but is preferably between 1,000 and less than 50,000. A number-average molecular weight of 1,000 or more provides excellent flexibility, while a number-average molecular weight of less than 50,000 results in low viscosity, making it easy to adjust the viscosity without solvents. A number-average molecular weight of 2,000 to 50,000 is more preferable.

[0027] <Polyol> Polyols are compounds that have two or more hydroxyl groups in their molecule. Representative examples include polyether polyols, polyester polyols, polycarbonate polyols, polyolefin polyols, and plant-derived polyols.

[0028] Furthermore, examples of compounds having two or more hydroxyl groups in the molecule include polyols obtained by starting with compounds having at least two active hydroxyl groups, such as low molecular weight polyols, aliphatic amine compounds, aromatic amine compounds, alkanolamines, or bisphenols, and adding alkylene oxides such as methylene oxide, ethylene oxide, propylene oxide, tetrahydrofuran, or polyoxytetramethylene oxide.

[0029] Examples of the low molecular weight polyols include bifunctional low molecular weight polyols or trifunctional or more low molecular weight polyols.

[0030] The bifunctional low molecular weight polyols are not particularly limited and include, for example, 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-octanediol. Examples include diols, polyoxyethylene glycol (additional moles of 10 or less), polyoxypropylene glycol (additional moles of 10 or less), cyclohexanediol, cyclohexanedimethanol, tricyclodecanedimethanol, cyclopentadienedimethanol, dimergol, 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.

[0031] The low molecular weight polyols with three or more functionalities are not particularly limited, and include, for example, 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-octantriol, 1,3,7-octantriol, 3,7-dimethyl-1,2,3-octantriol, 1,1,1-, 1, 1,1-Trimethylol decane, 1,2,10-decanetriol, 1,1,1-Trimethylol isoheptadecane, 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-methylhexane, 1,1,1-Trimethylol-3-methylhexane, 1,1,1-Trimethylol 1,1,1-Trimethylol-2-ethyl-hexane, 1,1,1-Trimethylol-3-ethyl-hexane, 1,1,1-Trimethylol isoheptadecane, 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 include 4',5-triol, sucrose, inositol, sorbitan, sorbitol, mannitol, saccharose, cellulose, and xylitol.

[0032] 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.

[0033] Examples of polyether polyols include polymers or copolymers of methylene oxide, ethylene oxide, propylene oxide, butylene oxide, tetrahydrofuran, etc., such as glycols like polyethylene glycol, polypropylene glycol, and poly(ethylene / propylene) glycol. Other examples include polyether polyols obtained by condensation of hexanediol, methylhexanediol, heptanediol, octanediol, or mixtures thereof.

[0034] Examples of polyester polyols include those obtained by the condensation reaction of the aforementioned low-molecular-weight polyol with a dibasic acid component.

[0035] Examples of dibasic acid components include aliphatic or aromatic dibasic acids such as terephthalic acid, adipic acid, azelaic acid, sebatic acid, dimer acid, hydrogenated dimer acid, phthalic anhydride, isophthalic acid, trimellitic acid, glutaric acid, pimelic acid, suberic acid, and sebacic acid, as well as their anhydrides. Other examples include polyester polyols obtained by ring-opening polymerization of cyclic ester compounds such as lactones, including ε-caprolactone, poly(β-methyl-γ-valerolactone), and polyvalerolactone.

[0036] Examples of polycarbonate polyols include those obtained by the reaction of the aforementioned low-molecular-weight polyols with carbonate compounds such as dialkyl carbonates, alkylene carbonates, and diaryl carbonates. Examples of dialkyl carbonates include dimethyl carbonate and diethyl carbonate, examples of alkylene carbonates include ethylene carbonate, and examples of diaryl carbonates include diphenyl carbonate.

[0037] 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.

[0038] Examples of plant-based polyols include castor oil, dimer acid, or polyols derived from soybean oil.

[0039] Among these, polyether polyols and polycarbonate polyols are preferred due to their superior flexibility.

[0040] The number-average molecular weight of the above polyol is preferably 400 to 5,000, and more preferably 700 to 3,500. A number-average molecular weight of 400 to 5,000 is preferable because it results in superior flexibility and impact resistance of the resulting cured product.

[0041] Furthermore, the polyol may be used in combination with the above-mentioned low-molecular-weight polyols, to the extent that it does not impair the effects of the present invention, for the purpose of adjusting the urethane bond concentration or introducing various functional groups.

[0042] <Polyisocyanate> Polyisocyanates can be any compound having two or more isocyanate groups in their molecule, such as aromatic, aliphatic, or alicyclic diisocyanates. Aromatic diisocyanates and alicyclic diisocyanates are preferred because the presence of an aromatic ring or alicyclic structure allows for moderate disintegration due to steric hindrance, resulting in excellent flexibility. Alicyclic diisocyanates having an alicyclic structure are more preferred.

[0043] 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.

[0044] 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.

[0045] 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(isocyanate methyl)cyclohexane, hydrogenated xylylene diisocyanate, dimer acid diisocyanate, norbornene diisocyanate, and the like.

[0046] <Polyamine> Polyamines can be any compound having two or more amino groups in their molecule, such as aromatic diamines, aliphatic diamines, alicyclic diamines, or polyether diamines. When the number average molecular weight is less than 300, the urea bonds are in close proximity, promoting the formation of a phase separation structure and resulting in excellent impact resistance. Preferably, the number average molecular weight is less than 250. If an aromatic ring or alicyclic structure is present, steric hindrance results in an appropriate crosslinking density and excellent flexibility; therefore, aromatic diamines and alicyclic diamines are preferred.

[0047] Examples of aromatic diamines include m-xylenediamine, p-xylenediamine, and m-phenylenediamine.

[0048] Examples of aliphatic diamines include ethylenediamine, diaminopropane, diaminobutane, diaminohexane, 2,5-dimethylhexamethylenediamine, hexamethylenediamine, trimethylhexamethylenediamine, diethylenetriamine, and iminobispropylamine.

[0049] Examples of alicyclic diamines include isophorone diamines and metacenediamines.

[0050] Polyetherdiamines are not particularly limited as long as they are compounds having two amino groups in their molecule and a repeating ether chain structure, but examples include poly(propylene glycol)diamine, poly(ethylene glycol)diamine, poly(tetramethylene ether glycol)diamine, and poly(propylene / ethylene glycol)diamine.

[0051] The method for producing polyurethane urea resin (A) is not limited, but it can preferably be produced by the following method. Step 1: A urethane reaction is carried out between a polyol and a polyisocyanate under conditions in which there is an excess of isocyanate groups relative to hydroxyl groups, thereby obtaining a urethane prepolymer having isocyanate groups at the molecular ends. Step 2: A urea reaction is carried out between a urethane prepolymer and a polyamine under conditions in which there is an excess of amino groups relative to the isocyanate groups, to obtain a polyurethane urea resin (A) having primary or secondary amino groups at the terminals.

[0052] The reactions in steps 1 and 2 may be carried out with or without a solvent. If a solvent is used in steps 1 and 2, a solvent-free polyurethane urea resin (A) can be obtained by removing the solvent under reduced pressure or atmospheric pressure during or after the reaction.

[0053] The urethane formation in step 1 and the urea formation reaction in step 2 are carried out using known reactions, and catalysts may be used to adjust the reactivity.

[0054] As catalysts, known metal catalysts, amine catalysts, etc., can be used. 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 0.01 to 0.05% by mass, based on the total mass of the polyol and polyisocyanate.

[0055] The content of polyurethane urea resin (A) is 20 to 70% by mass of the total 100% by mass of the organic components having primary amino groups and organic components having secondary amino groups contained in the curing agent (X). This range is preferable because it promotes phase separation formation and exhibits excellent heat resistance, adhesion, impact resistance, and flexibility. More preferably, it is 30 to 60%. The organic components having primary amino groups and organic components having secondary amino groups contained in the curing agent (X) refer to the organic components having primary amino groups, organic components having secondary amino groups, and organic components having both primary and secondary amino groups, among the polyurethane urea resin (A), liquid polyamine (B), other amine compounds, curing accelerators, and additives.

[0056] ≪Liquid polyamines with a cyclic structure (B)≫ The liquid polyamine (B) having a cyclic structure can be any compound that is liquid at room temperature (23°C), has a cyclic structure within its molecule, and has two or more primary or secondary amino groups. Examples include alicyclic polyamine compounds and aromatic polyamine compounds.

[0057] The molecular weight of the liquid polyamine (B) is preferably less than 350. A molecular weight of less than 350 allows for the formation of a good crosslinking structure, resulting in a cured product with excellent heat resistance, adhesion, and strength. More preferably, the molecular weight is less than 325.

[0058] Examples of alicyclic polyamine compounds include isophoronediamine, 1,3-bis(aminomethyl)cyclohexane, 1,4-bis(aminomethyl)cyclohexane, bis(aminomethyl)norbornane, 1,2-cyclohexanediamine, 4,4'-methylenebis(N-sec-butylcyclohexaneamine), 4,4'-methylenebis(2-methylcyclohexylamine), aminoethylpiperazine, 2-(aminomethyl)piperidine, and 1-(2-aminoethyl)piperidine.

[0059] Examples of aromatic polyamine compounds include m-xylenediamine, 4,4'-methylenebis(N-sec-butylaniline), diethyltoluenediamine, dimethylthiotoluenediamine, aminobenzylamine, N,N'-di-sec-butyl-p-phenylenediamine, 2,4-diamino-3,5-diethyltoluene, 2,6-diamino-3,5-diethyltoluene, and dimethylthiotoluenediamine.

[0060] As the amine compound, any known amine that cures epoxy resins can be used, as long as it does not impair flexibility. Examples include aliphatic amines, polyetheramines, alicyclic or aromatic amines that are solid at room temperature, monofunctional amines, and amide compounds.

[0061] <<Curing accelerator>> Examples of curing accelerators include tertiary amines and their salts, imidazoles and their salts, urea compounds, phosphorus compounds, organophosphine compounds and their salts, metal salts such as zinc octylate and tin octylate, compounds having hydroxyl groups such as phenols and alcohols, Lewis acids, and amine complex salts.

[0062] The curing accelerator is preferably present in an amount of 0.01 to 20% by mass relative to 100% by mass of the total organic components of the curing agent (X). Note that the total organic components of the curing agent (X) refer to the organic components excluding the inorganic filler.

[0063] ≪Additives≫ Examples of known additives include silane coupling agents, leveling agents or defoaming agents, fillers, propellants, plasticizers, superplasticizers, wetting agents, flame retardants, viscosity modifiers, preservatives, stabilizers, and colorants. Such additives include, but are not limited to, the following compounds.

[0064] Examples of silane coupling agents include trialkoxysilanes having vinyl groups such as vinyltrimethoxysilane and vinyltriethoxysilane; trialkoxysilanes having amino groups such as 3-aminopropyltriethoxysilane and N-(2-aminoethyl)3-aminopropyltrimethoxysilane; trialkoxysilanes having glycidyl groups such as 3-glycidoxypropyltrimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane and 3-glycidoxypropyltriethoxysilane; trialkoxysilanes having isocyanate groups such as 3-isocyanatetopropyltriethoxysilane; and trialkoxysilanes having mercapto groups such as 3-mercaptopropylmethyldimethoxysilane and 3-mercaptopropyltrimethoxysilane. The amount of silane coupling agent added is preferably 0.05 to 10% by mass relative to 100% by mass of the total organic components of the curing agent (X).

[0065] Examples of leveling agents include polyether-modified polydimethylsiloxane, polyester-modified polydimethylsiloxane, aralkyl-modified polymethylalkylsiloxane, polyester-modified hydroxyl-containing polydimethylsiloxane, polyether ester-modified hydroxyl-containing polydimethylsiloxane, acrylic copolymers, methacrylic copolymers, polyether-modified polymethylalkylsiloxane, alkyl acrylate copolymers, alkyl methacrylate copolymers, lecithin, and the like.

[0066] Examples of known defoaming agents include silicone resins, silicone solutions, copolymers of alkyl vinyl ethers, alkyl acrylates, and alkyl methacrylates.

[0067] [Main ingredient (Y)] The main component (Y) contains a liquid epoxy resin (C). The main component (Y) is not limited to the liquid epoxy resin (C), but may also include other epoxy compounds that contribute to the crosslinking reaction with the curing agent (X), as well as additives, as needed.

[0068] Liquid epoxy resin (C)

[0069] The liquid epoxy resin (C) is not particularly limited as long as it is a compound that is liquid at room temperature (23°C), but it is preferable that it has two or more epoxy groups in its molecule. Furthermore, it is preferable that the epoxy equivalent is 200 g / eq or less, and more preferably 150 to 200 g / eq. The epoxy equivalent of the liquid epoxy resin (C) can be determined by measurement in accordance with JIS K-7236. Note that the epoxy equivalent of the liquid epoxy resin (C) in this specification refers to the epoxy equivalent of each epoxy resin used. Liquid epoxy resin (C), when incorporated into the cross-linked structure during curing, exhibits an excellent glass transition temperature and contributes to improved heat-resistant adhesion.

[0070] Examples of liquid epoxy resin (C) include aromatic epoxy resins, alicyclic epoxy resins, aliphatic epoxy resins, and polyether epoxy resins. Among these, aromatic epoxy resins and alicyclic epoxy resins are preferred because they exhibit good adhesion. Aromatic epoxy resins are more preferred because they are readily available and have good glass transition temperature and adhesion.

[0071] Examples of aromatic epoxy resins include bisphenol A type epoxy resins, bisphenol F type epoxy resins, aromatic epoxy resins having an ester skeleton, aromatic glycidylamine type epoxy resins, cardanol-modified epoxy resins, p-tert-butylphenol glycidyl ether, phenyl glycidyl ether, and cresyl glycidyl ether. Among aromatic epoxy resins, bisphenol A type epoxy resins are preferred.

[0072] Examples of alicyclic epoxy resins include hydrogenated bisphenol A type epoxy resin, hydrogenated bisphenol F type epoxy resin, alicyclic glycidylamine type epoxy resin, alicyclic epoxy resin having an ester skeleton, cyclohexane type epoxy resin, cyclohexanedimethanol type epoxy resin, and limonene dioxide.

[0073] Examples of aliphatic epoxy resins include 1,6-hexanediol diglycidyl ether, 1,4-butanediol diglycidyl ether, ethylene glycol diglycidyl ether, neopentyl glycol diglycidyl ether, propylene glycol diglycidyl ether, 2-ethylhexyl monoglycidyl ether, glyceryl glycidyl ether, and trimethylolpropane triglycidyl ether.

[0074] Examples of polyether epoxy resins include polyethylene glycol diglycidyl ether and polypropylene glycol diglycidyl ether.

[0075] The ratio of the total number of moles of all epoxy groups in the curable resin composition to the total number of moles of all primary and secondary amino groups (epoxy groups / active hydrogen groups of primary and secondary amino groups) is preferably in the range of 0.5 to 2.0, and more preferably in the range of 0.6 to 1.5. When the ratio is in the range of 0.5 to 2.0, there are fewer unreacted functional groups, which ensures a high glass transition temperature by forming a good crosslink density, and allows for the expression of heat-resistant adhesion and excellent flexibility.

[0076] <Other epoxy compounds> In addition to liquid epoxy resin (C), the main component (Y) can be any epoxy compound that hardens with an amine curing agent, if necessary. Examples include solid epoxy resins.

[0077] <Additives> Examples of known additives include silane coupling agents, leveling agents or defoaming agents, fillers, propellants, plasticizers, superplasticizers, wetting agents, flame retardants, viscosity modifiers, preservatives, stabilizers, and colorants.

[0078] [[Curable resin composition]] The curable resin composition of the present invention is obtained by mixing a curing agent (X) containing a polyurethane urea resin (A) and a liquid polyamine (B) with a main component (Y) containing a liquid epoxy resin (C) in an appropriate range and causing a crosslinking reaction to form a good phase separation structure, ensuring a high glass transition temperature, and exhibiting excellent heat resistance, adhesion, flexibility, and impact resistance. In particular, it is preferable that the total amount of polyurethane urea resin (A) and liquid polyamine (B) contains 2.1 to 5.8 mmol / g of cyclic structures, as the interaction and steric hindrance of the cyclic structures promote the formation of an appropriate crosslinked structure, further enhancing flexibility and impact resistance. It is even more preferable that the total amount of polyurethane urea resin (A) and liquid polyamine (B) contains 2.4 to 5.1 mmol / g of cyclic structures.

[0079] The cyclic structure contained in the curable resin composition is a cyclic skeleton formed from three or more atoms, such as aromatic rings and alicyclic structures. Because steric hindrance moderately disrupts the stack structure of aromatic rings, improving flexibility, it is preferable that the polyurethane urea resin (A) or liquid polyamine (B) contains an alicyclic 6-membered ring structure. It is even more preferable that the total 100% by mass of the polyurethane urea resin (A), liquid polyamine (B), and liquid epoxy resin (C) contains 0.09 to 1.5 mmol / g of alicyclic 6-membered ring structures derived from the polyurethane urea resin (A) and liquid polyamine (B).

[0080] The method for producing the curable resin composition of the present invention is not particularly limited, and it can be obtained by mixing a curing agent (X) containing a polyurethane urea resin (A) and a liquid polyamine (B), and a main component (Y) containing a liquid epoxy resin (C) by a known method.

[0081] [[Cured product]] The cured product of the present invention is obtained by curing a curable resin composition under conditions of, for example, 5 to 180°C. A curing temperature of 25 to 150°C is preferred because a good crosslinking structure is formed, resulting in a high glass transition temperature and improved heat resistance, adhesion, and impact resistance. From the viewpoint of reducing environmental impact, a temperature of 130°C or lower is more preferable. When heat curing, pre-curing at a temperature below the glass transition temperature followed by main curing at a temperature above the glass transition temperature further improves the crosslinking structure, thereby improving heat resistance and strength.

[0082] The glass transition temperature of the cured product of the present invention is 100°C or higher, preferably 110°C or higher. If the glass transition temperature is 100°C or higher, excellent heat resistance can be achieved. As described above, the glass transition temperature can be adjusted by the type and amount of polyurethane urea resin (A), liquid polyamine (B), and liquid epoxy resin (C), as well as the curing conditions.

[0083] The cured product of the present invention can be used as a composite. A composite is obtained by combining a cured product of the curable resin composition of the present invention with any substrate, such as a laminate having a layer made of the above cured product on a substrate, or a cured product obtained by impregnating fibers or the like with a curable resin as a matrix resin and curing it.

[0084] The laminate can be formed using known lamination methods. For example, a curable resin composition can be applied to one surface of a substrate, and then another substrate can be placed on top of the layer of curable resin composition before curing, and cured to obtain a laminate having layers of cured material made of substrates and curable resin compositions.

[0085] The substrate used in the laminate is not particularly limited. Suitable substrates include, for example, metals such as stainless steel and aluminum, thermoplastic polymers such as polyethylene, polyurethane, polyacrylate and polycarbonate and their copolymers, thermosetting polymers such as vulcanized rubber, urea-formaldehyde foam, melamine resin, wood, carbon fiber reinforced plastics, glass fiber reinforced plastics and other fiber-reinforced plastics.

[0086] The curable resin composition of the present invention can be used for bonding various substrates. The substrates to be bonded may be the same or different. When used as an adhesive, the film thickness of the curable resin composition is preferably 10 μm to 10 mm.

[0087] The curable resin composition of the present invention has high adhesive strength and excellent impact resistance, and laminates using this curable resin composition are useful as structural adhesives for automobiles, large structures, and the like.

[0088] When impregnating fibers or the like with a curable resin composition as a matrix resin, the polyurethane urea resin (A), liquid polyamine (B), liquid epoxy resin (C), and other components are mixed by known methods, impregnated, and then cured at a temperature of 20 to 180°C. A good crosslinked structure is formed, resulting in a high glass transition temperature and improved heat resistance, adhesion, and impact resistance. Therefore, curing at a heating temperature of 60 to 150°C is preferable. From the viewpoint of reducing environmental impact, a temperature of 130°C or lower is even more preferable. When heat curing, pre-curing at a temperature below the glass transition temperature, followed by main curing at a temperature above the glass transition temperature, further improves the crosslinked structure, thereby enhancing heat resistance and strength.

[0089] The curable resin composition of the present invention has heat resistance and excellent flexibility, and composites using this curable resin composition as a matrix resin are useful for pressure vessels and wind turbine blades. [Examples]

[0090] The present invention will be described in more detail below with reference to examples, but these examples do not limit the scope of the present invention in any way. Unless otherwise specified, "parts" in the examples refers to "parts by mass," and "%" refers to "mass percent." In the table, "-" indicates that an ingredient is not included.

[0091] <Number average molecular weight (Mn)> The number-average molecular weights of polyols and polyurethane urea resins (A) were calculated by GPC (gel permeation chromatography) using values ​​converted from standard polystyrene. The measurements were performed using an ACQUITY UPLC (Waters), with a 3 mM triethylamine and 10 mM LiBr N,N-dimethylformamide solution as the eluent. Three TSKgelSuperHM-M columns (Tosoh Corporation) were connected in series, and the measurements were performed under conditions of a flow rate of 0.6 mL / min, an injection volume of 10 μL, and a column temperature of 40°C.

[0092] <Amine value> The amine value was measured in accordance with JIS K-7237.

[0093] The abbreviations for the compounds in Table 1 are shown below. <Polyol> P-400: Bifunctional polypropylene glycol, number average molecular weight 450, manufactured by ADEKA Corporation. P-2000: Bifunctional polypropylene glycol, number average molecular weight 2,000, manufactured by ADEKA Corporation. • C-1090: Bifunctional polycarbonate polyol, number average molecular weight 1,000, manufactured by Kuraray Co., Ltd. • C-2090: Bifunctional polycarbonate polyol, number average molecular weight 2,000, manufactured by Kuraray Co., Ltd. <Polyisocyanate> IPDI: Isophorone diisocyanate, molecular weight 222 MDI: Diphenylmethane diisocyanate, molecular weight 250 TODI: 3,3'-dimethyl-4,4'-biphenylenediisocyanate, molecular weight 264 • HDI: Hexamethylene diisocyanate, molecular weight 168 <Polyamine> IPDA: Isophorone diamine, molecular weight 170, amine value 659 mgKOH / g: Organic component having a primary amino group and alicyclic structure • MXDA: m-xylenediamine, molecular weight 136, amine value 824 mgKOH / g: an organic component having a primary amino group and an aromatic ring structure. • D-230: Polyoxypropylenediamine, molecular weight 230, amine value 490 mgKOH / g, manufactured by HUNTSMAN: Organic component with primary amino groups

[0094] (Manufacturing Example 1) In a dropping vessel equipped with a nitrogen gas inlet tube, stirrer, thermometer, and refluxer, 71.8 parts of C-2090 as a polyol, 16.0 parts of IPDI as a polyisocyanate, and 0.01% of dibutyltin dilaurate relative to the total mass of the polyol and polyisocyanate were charged and uniformly stirred. The mixture was then stirred under a nitrogen atmosphere at 100°C for 2 hours to synthesize an isocyanate-terminated prepolymer. After that, 50 parts of ethyl acetate were added to obtain an isocyanate-terminated prepolymer solution. Subsequently, in another container equipped with a nitrogen gas inlet tube, stirrer, thermometer, and refluxer, 12.2 parts of IPDA and 50 parts of ethyl acetate were charged. Under a nitrogen atmosphere at 40°C, the isocyanate-terminated prepolymer solution was added dropwise over 30 minutes while uniformly stirring, and the mixture was stirred for 1 hour to obtain a polyurethane urea resin solution having primary amino groups at the ends. The solvent in the obtained polyurethane urea resin solution was removed under reduced pressure to obtain polyurethane urea resin (A-1). The reaction endpoint was determined by FT-IR at an absorption point (2270 cm⁻¹) derived from the isocyanate group. -1 This was confirmed by the disappearance of the surrounding area. The number-average molecular weight of the obtained polyurethane urea resin (A-1) was 4000, and the amine value was 28.3 mgKOH / g.

[0095] (Manufacturing Examples 2-3 and 5, Comparative Manufacturing Example 1) Except for the compounds and formulations shown in Table 1, the same procedure as in Production Example 1 was performed to obtain the polyurethane urea resins (A-2 to A-3, A-5, P-1) for Production Examples 2-3 and 5, and Comparative Production Example 1. The number-average molecular weights and amine values ​​of the obtained polyurethane urea resins (A-2 to A-3, A-5, P-1) are shown in Table 1.

[0096] (Manufacturing example 4) In a dropping vessel equipped with a nitrogen gas inlet tube, stirrer, thermometer, and refluxer, 14.5 parts of P-400 as a polyol, 14.4 parts of IPDI as a polyisocyanate, and 0.01% of dibutyltin dilaurate relative to the total mass of the polyol and polyisocyanate were charged and uniformly stirred. The mixture was then stirred under a nitrogen atmosphere at 100°C for 2 hours to synthesize an isocyanate-terminated prepolymer. After that, 50 parts of ethyl acetate were added to obtain an isocyanate-terminated prepolymer solution. Subsequently, in another container equipped with a nitrogen gas inlet tube, stirrer, thermometer, and refluxer, 71.1 parts of IPDA and 50 parts of ethyl acetate were charged. Under a nitrogen atmosphere at 40°C, the isocyanate-terminated prepolymer solution was added dropwise over 30 minutes while uniformly stirring, and the mixture was stirred for 1 hour to obtain a mixed solution of polyurethane urea resin (A-4) having primary amino groups at the ends and liquid polyamine (IPDA). The solvent in the resulting mixed solution was removed under reduced pressure to obtain a mixture of polyurethane urea resin (A-4) and liquid polyamine (IPDA) in a mass ratio of 40:60. The endpoint of the reaction was determined by FT-IR at an absorption (2270 cm⁻¹) derived from the isocyanate group. -1 This was confirmed by the disappearance of the surrounding area. The number-average molecular weight of the obtained polyurethane urea resin (A-4) was 1100, and the amine value of the mixed solution was 224 mgKOH / g.

[0097] [Table 1]

[0098] The abbreviations for the compounds in Tables 2 and 3 are shown below. <Liquid polyamine (B)> IPDA: Isophorone diamine, molecular weight 170, amine value 659 mgKOH / g: Organic component having a primary amino group and alicyclic structure • MXDA: m-xylenediamine, molecular weight 136, amine value 824 mgKOH / g: an organic component having a primary amino group and an aromatic ring structure. • Unilink4200: 4,4'-Methylenebis(N-sec-butylaniline), molecular weight 310, amine value 362 mgKOH / g: Organic component having a secondary amino group and aromatic ring structure. <Amine compounds> • P-1: Polyurethane urea resin with secondary amino groups at the ends, manufactured in Comparative Production Example 1: Organic component with tertiary amino groups • D-230: Polyoxypropylenediamine, molecular weight 230, amine value 490 mgKOH / g, manufactured by HUNTSMAN: Organic component with primary amino groups • TETA: Triethylenetetramine, molecular weight 146: an organic component having a primary amino group. <Liquid epoxy resin (C)> jER828: Bisphenol A type epoxy resin, epoxy equivalent 190 g / eq, manufactured by Mitsubishi Chemical Corporation. jER806: Bisphenol F type epoxy resin, epoxy equivalent 170 g / eq, manufactured by Mitsubishi Chemical Corporation. Tetrad-X: N,N,N',N'-tetraglycidyl-m-xylenediamine, epoxy equivalent 98 g / eq, manufactured by Mitsubishi Gas Chemical Company. EX-252: Hydrogenated bisphenol A epoxy resin, epoxy equivalent 213 g / eq, manufactured by Nagase ChemteX Corporation. EX-146: p-tert-butylphenyl glycidyl ether, epoxy equivalent 225 g / eq, manufactured by Nagase ChemteX Corporation. <Epoxy compounds> • MX-153: Core-shell type epoxy resin modifier, epoxy equivalent 270g / eq, manufactured by Kaneka Corporation.

[0099] <Preparation of curable resin composition> [Example 1] The curable resin composition of Example 1 was prepared by stirring and degassing 1.5 parts of the polyurethane urea resin (A-1) obtained in Production Example 1, 2.2 parts of IPDA as a liquid polyamine (B), and 10 parts of jER828 as a liquid epoxy resin (C) at room temperature.

[0100] [Examples 2-10, 12-19 and Comparative Examples 1-8] Except for the changes in the compound composition shown in Tables 2 and 3, the same procedure as in Example 1 was performed to prepare the curable resin compositions for Examples 2-10, 12-19, and Comparative Examples 1-8.

[0101] [Example 11] The curable resin composition of Example 11 was prepared by stirring and degassing 3.5 parts of a mixture of the polyurethane urea resin (A-4) obtained in Production Example 4 and liquid polyamine (IPDA) (1.4 parts polyurethane urea resin (A-4), 2.1 parts IPDA) and 10 parts of jER828 as liquid epoxy resin (C) at room temperature.

[0102] [Table 2]

[0103] [Table 3]

[0104] (Measurement of glass transition temperature) Each curable resin composition was filled into a 1 mm thick sheet mold, the surface was smoothed, and after pre-curing at 60°C for 30 minutes, it was fully cured at 130°C for 15 minutes. The pieces were then cut to a length of 2 cm and a width of 5 mm to prepare test specimens for measuring the glass transition temperature. The glass transition temperature was derived from the peak temperature of the tanδ curve measured using a dynamic viscoelasticity analyzer under a heating rate of 10°C / min. (Evaluation Criteria) H: Glass transition temperature is 110°C or higher M: Glass transition temperature is 100°C or higher, but less than 110°C. L: Glass transition temperature is less than 100°C

[0105] <Evaluation of curable resin compositions> The curable resin compositions prepared in the examples and comparative examples were subjected to the following tests. The results are shown in Tables 2 and 3.

[0106] [Heat-resistant adhesion] Each curable resin composition was applied to a stainless steel substrate (100 mm long, 25 mm wide, 2 mm thick) to a length of 10 mm, width of 25 mm, and thickness of 0.2 mm. This was then bonded to another stainless steel substrate, and under pressure to maintain a thickness of 0.2 mm, it was pre-cured at 60°C for 30 minutes, followed by full curing at 130°C for 15 minutes to obtain test specimens for measuring heat-resistant adhesion. The obtained test specimens were subjected to shear adhesion measurement using a tensile testing machine at a temperature of 100°C and a tensile speed of 50 mm / min, and evaluated according to the following criteria. (Evaluation Criteria) ◎: Shear adhesion strength of 15 MPa or higher (good) ○: Shear adhesive strength of 8 MPa or more and less than 15 MPa (usable) ×: Shear adhesive strength is less than 8 MPa (not usable)

[0107] [Flexibility] Each resin composition was filled into a 1 mm thick No. 3 dumbbell mold, the surface was smoothed, and after pre-curing at 60°C for 30 minutes, the material was fully cured at 130°C for 15 minutes to prepare dumbbell-shaped test specimens for evaluation. The obtained test specimens were subjected to a tensile test using a tensile testing machine at a temperature of 25°C and a relative humidity of 50%, with a tensile speed of 10 mm / min, to measure the elongation at break. (Evaluation Criteria) ◎: Elongation at break is 10% or more (good) ○: Elongation at break is 5% or more and less than 10% (usable) ×: Breaking elongation is less than 5% (unusable)

[0108] [Impact Resistance] Each curable resin composition was applied to a carbon fiber reinforced plastic substrate (100 mm long, 25 mm wide, 2 mm thick) to a length of 15 mm, width of 25 mm, and thickness of 0.3 mm. This was then bonded to another carbon fiber reinforced plastic substrate, and under pressure to maintain a thickness of 0.3 mm, the substrate was pre-cured at 60°C for 30 minutes, followed by full curing at 130°C for 15 minutes to obtain impact resistance test specimens. Under conditions of 25°C and 50% relative humidity, an impact was applied to the bonded portion of the obtained test specimens in the thickness direction using a DuPont impact test. The test was performed up to a maximum of 100 times, and the test was terminated when the specimen fractured or the substrate broke. The following criteria were used to determine the outcome based on the number of attempts until fracture or whether or not the substrate was damaged. In the DuPont impact test, both ends of the test specimen were fixed so that the thickness direction of the substrate was perpendicular to the ground. The tip of a drill bit with a 1 / 2-inch rounded end was then placed vertically on the hardened resin portion of the fixed test specimen, and a 500g weight was dropped from a height of 5cm onto this grounded drill bit. (Evaluation Criteria) ◎: Does not break even after 100 tests. Or the substrate breaks by the 100th test. (Good) ○: Breaks after 20-99 uses, but does not damage the base material. (Usable) ×: Breaks after 19 uses or less, but does not damage the substrate. (Not usable)

[0109] <Overall Rating> The curable resin compositions prepared in the examples and comparative examples were comprehensively evaluated according to the following criteria. The evaluation results are shown in Tables 2 and 3.

[0110] (Overall evaluation criteria) ◎: The evaluation result is ◎ in all evaluation items. (Excellent) ○: The rating is ○ or higher in all evaluation items. (Usable) ×: A "×" rating is given in any of the evaluation items. (Not usable)

[0111] The curable resin composition of the present invention yielded excellent results in terms of heat resistance, adhesion, flexibility, and impact resistance. On the other hand, the curable resin composition of the comparative example showed inferior results in some or all of the heat resistance, adhesion, flexibility, and impact resistance compared to the example.

Claims

1. It contains a curing agent (X) containing polyurethane urea resin (A) and liquid polyamine (B), and a main component (Y) containing liquid epoxy resin (C), Furthermore, a solvent-free curable resin composition characterized by satisfying all of the following conditions (i) to (iv). (i) Polyurethane urea resin (A) has a primary amino group or a secondary amino group at its terminus. (ii) The liquid polyamine (B) has a cyclic structure and contains a primary amino group or a secondary amino group. (iii) The curing agent (X) contains 20 to 70% by mass of polyurethane urea resin (A) in a total of 100% by mass of the organic component having a primary amino group and the organic component having a secondary amino group. (iv) The glass transition temperature of the cured product made from the curable resin composition is 100°C or higher.

2. The curable resin composition according to claim 1, wherein the number average molecular weight of the liquid polyamine (B) is less than 350.

3. The curable resin composition according to claim 1, wherein the number average molecular weight of the polyurethane urea resin (A) is 1,000 or more and less than 50,000.

4. The curable resin composition according to claim 1, comprising 2.1 to 5.8 mmol / g of cyclic structures in the total amount of the polyurethane urea resin (A) and the liquid polyamine (B).

5. A cured product comprising the curable resin composition according to any one of claims 1 to 4.

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