Damping adhesive composition

Abstract

To provide a damping adhesive composition enabling compatibility of damping performance and rigidity.SOLUTION: The damping adhesive composition comprises at least one main epoxy resin selected from the group consisting of glycidyl ether type epoxy resin, glycidyl ester type epoxy resin, and glycidyl amine type epoxy resin, a flexible epoxy resin, a monofunctional or bifunctional epoxy reactive diluent, and a curing agent.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a damping adhesive composition that can be used for structural bonding of, for example, body panels of automobiles and industrial vehicles, and in particular to a damping adhesive composition that can achieve both rigidity and damping properties. [Background technology]

[0002] As a technology for achieving both weight reduction and improved rigidity in automobile and other vehicle bodies, a technology that combines the use of structural adhesives and spot welding (weld bond method) has been put into practical use to replace or reinforce conventional joining methods such as welding, bolts and nuts, or rivets to join body panels made of steel plates, etc. With this weld bond method, the body panels are joined by surface joining using structural adhesives in addition to point joining using spot welding alone, thereby increasing rigidity and improving driving stability (handling stability) without significantly increasing the weight of the vehicle body.

[0003] In recent years, the automotive industry has seen a growing need to improve not only driving stability but also emotional performance such as NVH (noise, vibration, and harshness) performance and ride comfort. For this reason, in addition to suppressing vibration by increasing the rigidity of the car body, technology that provides damping is also required. However, the method of suppressing vibration in the car body by adding vibration-proofing and sound-proofing materials to the vibration transmission path has the problem of increasing weight. Therefore, attempts have been made to impart damping properties to structural adhesives used to join body panels and body frames, which are vibration response and transmission systems.

[0004] For example, Patent Document 1 discloses an adhesive for automobile structures that comprises 5 to 80% by weight of a rubber-modified epoxy resin obtained by reacting a bisphenol-type epoxy resin with a butadiene-acrylonitrile-(meth)acrylic acid copolymer, 5 to 80% by weight of a urethane-modified epoxy resin, 0.1 to 40% by weight of a bisphenol-type epoxy resin, 5 to 80% by weight of an epoxy resin composition in which rubber particles having inorganic fine powder attached to their surfaces are dispersed, 0.1 to 40% by weight of a dimer acid glycidyl ester-type epoxy resin, and 0.1 to 30% by weight of a latent curing agent, and that exhibits a damping factor (tan δ) in dynamic viscoelasticity of 0.2 or greater over a wide range from low to high temperatures. Furthermore, Patent Document 2 discloses an automotive adhesive containing a specific epoxy resin, a block urethane resin, and a curing agent for a specific reactive diluent. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2-150484 [Patent Document 2] Japanese Patent Application Publication No. 2017-52922 Summary of the Invention [Problem to be solved by the invention]

[0006] However, the technology of Patent Document 1 increases the loss factor tanδ by including a rubber-based structure, and the technology of Patent Document 2 increases the loss factor tanδ by including a specific epoxy-based resin, a block urethane resin, and a specific reactive diluent. Therefore, although damping properties can be achieved, it is difficult to ensure rigidity.

[0007] Therefore, an object of the present invention is to provide a damping adhesive composition that can achieve both damping properties and rigidity. [Means for solving the problem]

[0008] The damping adhesive composition of the invention of claim 1 contains one or more main epoxy resins selected from the group consisting of glycidyl ether type epoxy resins, glycidyl ester type epoxy resins, and glycidyl amine type epoxy resins, a flexible epoxy resin, a monofunctional or difunctional reactive epoxy-based reactive diluent, and a curing agent.

[0009] The main epoxy resin may be one of a glycidyl ether type epoxy resin, a glycidyl ester type epoxy resin, and a glycidyl amine type epoxy resin, or two or more of these may be used in combination. Those that are liquid at room temperature are preferred, and among these, bisphenol A type epoxy resins, which are glycidyl ether type epoxy resins, are preferred.

[0010] The flexible epoxy resin is one in which an elastic structure is incorporated into the resin skeleton by reacting an epoxy resin with a flexible reactive oligomer. For example, polyoxyalkylene-type epoxy resins, urethane-modified epoxy resins, rubber-modified resins, block urethane resins, etc. can be used, and polyoxyalkylene-type epoxy resins containing polyoxyalkylene bonds in the resin skeleton are preferred.

[0011] The epoxy-based reactive diluent is a monofunctional reactive diluent (monoepoxide) and / or a bifunctional reactive diluent (diepoxide), and is preferably a monoglycidyl or diglycidyl type. A monofunctional reactive epoxy-based reactive diluent may be used alone, a bifunctional reactive diluent may be used alone, or both may be used in combination. Examples of the curing agent include various aliphatic, aromatic, and cycloaliphatic amines, disiamides, and acid anhydrides.

[0012] The damping adhesive composition of the invention according to claim 2 further contains a coumarone resin. The coumarone resin is preferably liquid at room temperature, and may be a coumarone polymer or a copolymer such as a coumarone-indene copolymer or a coumarone-indene-styrene copolymer.

[0013] The flexible epoxy resin of the damping adhesive composition of the invention according to claim 3 is preferably a bisphenol alkylene oxide modified epoxy resin. The bisphenol alkylene oxide-modified epoxy resin (diglycidyl ether of an alkylene oxide adduct of a bisphenol-type compound) is preferably a bisphenol A alkylene oxide-modified epoxy resin, and more preferably polypropylene bisphenol A diglycidyl ether (diglycidyl ether of a propylene oxide adduct of bisphenol A) or ethylene bisphenol A diglycidyl ether (diglycidyl ether of an ethylene oxide adduct of bisphenol A).

[0014] The monofunctional reactive epoxy-based reactive diluent of the damping adhesive composition of the invention according to claim 4 is preferably a higher alcohol monoepoxide or an aromatic skeleton monoepoxide. The higher alcohol monoepoxide may be either a straight-chain or branched type, and is preferably a straight-chain alcohol monoglycidyl ether. The aromatic backbone (aromatic type) monoepoxide is preferably a monoglycidyl ether having an aromatic group.

[0015] The bifunctional reactive epoxy-based reactive diluent of the damping adhesive composition of the invention of claim 5 is preferably a glycol-skeleton diepoxide or an aliphatic-skeleton diepoxide. The glycol-skeleton diepoxide is preferably a polyoxyalkylene-based diglycidyl ether, and more preferably one having propylene oxide. The aliphatic skeleton (aliphatic type) diepoxide is preferably a diglycidyl ether having an aliphatic group.

[0016] The amount of the flexible epoxy resin in the damping adhesive composition of the invention according to claim 6 is preferably in the range of 5 to 80 parts by mass, more preferably 10 to 70 parts by mass, and even more preferably 20 to 60 parts by mass, per 100 parts by mass of the main epoxy resin. Note that, when a single epoxy resin is used, the amount per 100 parts by mass of the main epoxy resin is that per 100 parts by mass of that single epoxy resin, and when two or more epoxy resins are used, the amount per 100 parts by mass is that per 100 parts by mass of the total amount of those epoxy resins.

[0017] The amount of the epoxy-based reactive diluent in the damping adhesive composition of the invention according to claim 7 is preferably 10 to 100 parts by mass, more preferably 15 to 90 parts by mass, and even more preferably 20 to 80 parts by mass, per 100 parts by mass of the main epoxy resin. The amount of the epoxy-based reactive diluent refers to the amount of the monofunctional epoxy-based reactive diluent when a monofunctional epoxy-based reactive diluent is used alone; it refers to the amount of the bifunctional epoxy-based reactive diluent when a bifunctional epoxy-based reactive diluent is used alone; and it refers to the total amount of the monofunctional epoxy-based reactive diluent and the bifunctional epoxy-based reactive diluent when both are used together.

[0018] The coumarone resin in the damping adhesive composition of the invention of claim 8 is preferably in the range of 5 parts by mass or more and 80 parts by mass or less, more preferably 10 parts by mass or more and 70 parts by mass or less, and even more preferably 20 parts by mass or more and 60 parts by mass or less, per 100 parts by mass of the main epoxy resin.

[0019] The coumarone resin in the damping adhesive composition of the invention according to claim 9 preferably has a phenol group at its terminal. [Effects of the Invention]

[0020] The damping adhesive composition according to the invention of claim 1 contains one or more main epoxy resins selected from the group consisting of glycidyl ether type epoxy resins, glycidyl ester type epoxy resins, and glycidyl amine type epoxy resins, a flexible epoxy resin, a monofunctional or difunctional reactive epoxy-based reactive diluent, and a curing agent. By using a combination of one or more main epoxy resins selected from the group consisting of glycidyl ether type, glycidyl ester type, and glycidyl amine type epoxy resins as the epoxy resin, and a flexible epoxy resin, and further using a monofunctional and / or difunctional reactive epoxy-based reactive diluent, this combination ensures both damping performance and rigidity over a wide temperature range, thereby achieving both damping performance and rigidity.

[0021] According to the damping adhesive composition of the invention of claim 2, since it further contains a coumarone resin, in addition to the effect of claim 1, it is possible to improve damping properties and rigidity.

[0022] According to the damping adhesive composition of the invention of claim 3, the flexible epoxy resin is preferably a bisphenol alkylene oxide-modified epoxy resin, so in addition to the effect of claim 1, it is possible to improve damping properties without significantly reducing rigidity.

[0023] According to the damping adhesive composition of the invention of claim 4, the monofunctional reactive epoxy-based reactive diluent is preferably a higher alcohol monoepoxide or an aromatic backbone monoepoxide, so in addition to the effect of claim 1, it is possible to improve damping properties without significantly reducing rigidity.

[0024] According to the damping adhesive composition of the invention of claim 5, the bifunctional reactive epoxy-based reactive diluent is preferably a glycol-skeleton diepoxide or an aliphatic-skeleton diepoxide, and therefore, in addition to the effect of claim 1, it is possible to increase rigidity without significantly reducing damping properties at room temperature.

[0025] According to the damping adhesive composition of the invention of claim 6, the flexible epoxy resin is preferably in the range of 5 to 80 parts by mass, more preferably 10 to 70 parts by mass, and even more preferably 20 to 60 parts by mass per 100 parts by mass of the main epoxy resin, so in addition to the effect of claim 1, it is possible to achieve both high damping and high rigidity.

[0026] According to the damping adhesive composition of the invention of claim 7, the epoxy-based reactive diluent is preferably in the range of 10 to 100 parts by mass, more preferably in the range of 15 to 90 parts by mass, and even more preferably in the range of 20 to 80 parts by mass, per 100 parts by mass of the main epoxy resin. Therefore, in addition to the effect of claim 1, it is possible to achieve both damping properties and rigidity while ensuring applicability.

[0027] According to the damping adhesive composition of the invention of claim 8, the coumarone resin is preferably in the range of 5 to 80 parts by mass, more preferably 10 to 70 parts by mass, and even more preferably 20 to 60 parts by mass, per 100 parts by mass of the main epoxy resin. Therefore, in addition to the effect of claim 2, it is possible to achieve both high damping and high rigidity while ensuring ease of application.

[0028] According to the damping adhesive composition of the invention of claim 9, the coumarone resin has a phenol group at its terminal, and therefore in addition to the effect of claim 2, it is possible to further improve damping properties and rigidity. DETAILED DESCRIPTION OF THE INVENTION

[0029] [Embodiment Mode] Hereinafter, an embodiment of the present invention will be described. The damping adhesive composition (hereinafter sometimes simply referred to as "adhesive composition") according to an embodiment of the present invention contains one or more main epoxy resins selected from the group consisting of glycidyl ether-type epoxy resins, glycidyl ester-type epoxy resins, and glycidyl amine-type epoxy resins, a flexible epoxy resin, a monofunctional or difunctional reactive epoxy-based reactive diluent, and a curing agent.

[0030] The damping adhesive composition of this embodiment is a curable epoxy adhesive composition whose basic composition is an epoxy resin and a curing agent for the epoxy resin, i.e., an epoxy compound having two or more epoxy groups (oxirane rings) in the molecule and a curing agent component having active hydrogen and catalytic action, and becomes a three-dimensional cured product by the reaction between the epoxy resin and the curing agent.

[0031] Examples of glycidyl ether type epoxy resins include bisphenol type epoxy resins obtained by reacting epichlorohydrin with phenolic compounds such as bisphenol A type (bisphenol A diglycidyl ether), bisphenol F type (bisphenol F diglycidyl ether), brominated bisphenol A type, hydrogenated bisphenol A type, bisphenol S type, bisphenol AD ​​type, bisphenol AF type, bisphenol AP type, bisphenol B type, bisphenol BP type, bisphenol C type, bisphenol G type, bisphenol M type, and bisphenol P type; and epoxy resins having a bisphenyl group. Examples of epoxy compounds include biphenyl epoxy resins, which are obtained by reacting a novolac compound such as a phenol novolac or orthocresol novolac with epichlorohydrin, epoxy compounds obtained by reacting a polyhydric phenol with epichlorohydrin, epoxy compounds obtained by reacting an aliphatic polyhydric alcohol with epichlorohydrin, and epoxy compounds having a tricyclodecane ring (for example, epoxy compounds obtained by a production method in which dicyclopentadiene and a cresol such as m-cresol or a phenol are polymerized, followed by reaction with epichlorohydrin).

[0032] Examples of glycidyl ester type epoxy resins include epoxy compounds of synthetic fatty acids such as dimer acid (dimer acid diglycidyl ester, etc.), and epoxy compounds of phthalic acid (tetrahydrophthalic acid diglycidyl ester, hexahydrophthalic acid diglycidyl ester, phthalic acid diglycidyl ester). Glycidylamine-type epoxy resins include N,N,N',N'-tetraglycidyldiaminodiphenylmethane (TGDDM), tetraglycidyl-m-xylylenediamine, triglycidyl-p-aminophenol, N,N-diglycidylamino-1,3-glycidylphenyl ether (DGAGPE), N,N-diglycidylaniline, triglycidyl isocyanate (TGIC), 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, and aminophenol types. These epoxy resins may be used alone or in combination of two or more.

[0033] Among the above epoxy resins, diglycidyl ether epoxy resins are preferred, and among these, bisphenol A epoxy resins are more preferred. In particular, bisphenol A diglycidyl ether (DGEBA), which is derived from the reaction of bisphenol A, which has active hydrogen, with epichlorohydrin, is suitable as the base (main) component of epoxy resins because it is available at low cost.

[0034] Bisphenol A epoxy resins and the like range from liquid to solid depending on the molecular weight. However, from the viewpoint of ease of handling and preparation, low-molecular-weight resins that are liquid to semi-solid at room temperature are preferred. Bisphenol A epoxy resins that are liquid at room temperature have a number-average molecular weight (Mn) of, for example, 250 to 800, preferably 300 to 700, and more preferably 300 to 600, and an epoxy equivalent of, for example, 120 to 450 g / eq, preferably 130 to 400 g / eq, and more preferably 140 to 300 g / eq. The epoxy equivalent refers to the number of grams of resin containing 1 gram equivalent of epoxy groups (unit: g / eq). This epoxy equivalent is a value measured in accordance with JIS K7236:2001. Liquid epoxy resins preferably have a viscosity in the range of 700 to 90,000 mPa·s / 25°C, more preferably 5,000 to 40,000 mPa·s / 25°C, and even more preferably 10,000 to 20,000 mPa·s / 25°C. If the viscosity is within this range, the resin is easy to handle and can easily be adjusted to a viscosity suitable for application of the adhesive composition.

[0035] Commercially available bisphenol A epoxy resins include, for example, ADEKA Resin EP-4100, 4100G, 4100E, 4400, 4520S, 4530, EP-4100TX, EP-4300E from ADEKA Corporation, and NAN YA PLASTICS Examples of suitable acrylic acid esters include, but are not limited to, NPEL-127, 127E, 127H, 128, 128E, 128G, 128R, 128S, 134, 134L, 136, and 231 from OXALIS CHEMICALS CORP., EPO (registered trademark) 825 from OXALIS CHEMICALS CORP., jER (registered trademark) 825, 827, 828, 828EL, 828US, 828XA, and 834 from Mitsubishi Chemical Corporation, and EPICLON 840, 840-S, 850, 850-S, and 850-LC from DIC Corporation.

[0036] Flexible epoxy resins are epoxy resins that incorporate an elastic structure into the resin skeleton by reacting a flexible reactive oligomer with the epoxy resin. In other words, they are epoxy resins with a flexible chain structure within the molecule. Examples of such resins include polyoxyalkylene epoxy resins, urethane-modified epoxy resins, rubber-modified resins, and block urethane resins. Preferred are polyoxyalkylene epoxy resins that contain polyoxyalkylene bonds in the resin skeleton (flexibility is imparted by the free vibration of ether groups). Among polyoxyalkylene epoxy resins (alkylene oxide-added epoxy resins), bisphenol epoxy resins containing an alkylene oxide skeleton (containing a glycidyl ether group at the end of the main chain with the longest molecular chain among the molecular chains constituting the epoxy resin, and an oxyalkylene group bonded to the glycidyl ether group) are preferred, and bisphenol A alkylene oxide-modified epoxy resins are more preferred. Bisphenol A alkylene oxide-modified epoxy resins are those obtained by modifying bisphenol A epoxy resins with aliphatic polyethers, i.e., by epoxidizing a polyol in which an alkylene oxide such as ethylene oxide or propylene oxide is added to a bisphenol A epoxy resin. For example, there are bisphenol A epoxy resins having a flexible skeleton and a polar skeleton in the main chain, such as an ethyleneoxyethyl group, a di(ethyleneoxy)ethyl group, a tri(ethyleneoxy)ethyl group, a propyleneoxypropyl group, a di(propyleneoxy)propyl group, a tri(propyleneoxy)propyl group, or an alkylene group having 2 to 15 carbon atoms. This allows for improved damping with minimal loss of rigidity. Among these, polypropylene bisphenol A diglycidyl ether (diglycidyl ether of a propylene oxide adduct of bisphenol A) or polyethylene bisphenol A diglycidyl ether (diglycidyl ether of an ethylene oxide adduct of bisphenol A) is preferred, with polypropylene bisphenol A diglycidyl ether being particularly preferred. The polyoxyalkylene epoxy resin as the flexible epoxy resin has an epoxy equivalent of, for example, 150 to 800 g / eq, preferably 200 to 750 g / eq, and more preferably 250 to 700 g / eq, and is a liquid with a viscosity of, for example, 300 to 10,000 mPa·s / 25°C, and preferably 400 to 8,000 mPa·s / 25°C.

[0037] Commercially available polyoxyalkylene epoxy resins as flexible epoxy resins include EP-4000 and 4005 manufactured by ADEKA Corporation, and Newpol BP-5P manufactured by Sanyo Chemical Industries, Ltd., but are not limited to these.

[0038] The flexible epoxy resin is preferably blended in an amount of 5 to 80 parts by mass, more preferably 10 to 70 parts by mass, and even more preferably 20 to 60 parts by mass, per 100 parts by mass of one or more main epoxy resins selected from the group consisting of glycidyl ether type epoxy resins, glycidyl ester type epoxy resins, and glycidyl amine type epoxy resins. If the amount of flexible epoxy resin is too high and the amount of main epoxy resin such as bisphenol A liquid epoxy resin is relatively low, the elastic modulus will be impaired. On the other hand, if the amount of flexible epoxy resin is too low, the loss factor at room temperature will not be high and damping properties will be impaired. Within the above range, it is possible to achieve both high damping properties and high rigidity. The flexible epoxy resin is not included in the one or more main epoxy resins selected from the group consisting of the glycidyl ether type epoxy resin, the glycidyl ester type epoxy resin, and the glycidyl amine type epoxy resin.

[0039] Thus, by using one or more main epoxy resins selected from the group consisting of glycidyl ether type epoxy resins, glycidyl ester type epoxy resins, and glycidyl amine type epoxy resins in combination with a flexible epoxy resin, the glass transition temperatures (T g) of flexible epoxy resins. g ) is the glass transition temperature (T g ), it is possible to increase the loss factor and damping over a wide temperature range. The total amount of the main epoxy resin and flexible epoxy resin is, for example, 50 to 900 parts by mass, preferably 100 to 800 parts by mass, more preferably 200 to 600 parts by mass, and even more preferably 300 to 500 parts by mass, relative to 100 parts by mass of the total amount of the adhesive composition, thereby increasing adhesive strength.

[0040] As the curing agent, those typically used for curing epoxy resins can be used. They may be of a polyaddition type that has an active group (active hydrogen) that reacts with the epoxy group, ring-opens the epoxy group, and the curing agent itself becomes part of the resin network structure, or they may be of a catalyst type (sometimes called a curing accelerator or curing aid) in which the curing agent acts catalytically (as an initiator) to add-polymerize the epoxy group by a cationic or anionic mechanism, or both may be used in combination.

[0041] Examples of polyaddition-type compounds include aliphatic and aromatic amines such as dicyandiamide (DICY), 4,4'-diaminodiphenyl sulfone (DDS), and diaminodiphenylmethane (DDM), imidazole compounds such as 2-n-heptadecylimidazole, organic acid hydrazide compounds such as adipic acid dihydrazide, stearic acid dihydrazide, isophthalic acid dihydrazide, and dibasic acid hydrazide, urea compounds such as N,N-dialkylurea derivatives and N,N-dialkylthiourea derivatives, polyaminoamides, acid anhydrides such as tetrahydrophthalic anhydride, semicarbazide, and cyanoacetate. Examples of suitable phenols include amine compounds such as methyl methyl ether, isophoronediamine, and m-phenylenediamine, aminotriazoles such as 3-amino-1,2,4-triazole, N-aminoethylpiperazine, melamines, guanamines such as acetoguanamine and benzoguanamine, guanidines, dimethylureas, boron trifluoride complex compounds, boron trichloride complex compounds, Lewis acid complexes, polymercaptan, liquid phenols such as trisdimethylaminomethylphenol, polythiols, triphenylphosphine, ketimine compounds, sulfonium salts, onium salts, phenol novolac resins, and melamine derivatives. These may be used alone or in combination of two or more.

[0042] Among these, from the viewpoints of storage stability, workability in formulation, and the like, preferred are amine-based curing agents such as aliphatic amines, aromatic amines, or modified amines, such as dicyandiamide and its derivatives (e.g., polyepoxide addition modified products, amidation modified products, Mannich modified products, and Michael addition modified products), diaminodiphenylmethane, and 4,4'-diaminodiphenylsulfone, as well as acid anhydrides, boron trifluoride amine complexes (boron trifluoride amine complex salts), imidazole compounds (e.g., 2-n-heptadecylimidazole), organic acid hydrazides (e.g., adipic acid dihydrazide, isophthalic acid dihydrazide), N,N-dialkyl urea derivatives, and N,N-dialkyl thiourea derivatives, which do not undergo chemical reaction with epoxy resins at room temperature but are activated by heating. In particular, when the attenuation adhesive composition of this embodiment is used as a structural adhesive composition to be applied to the joining portions of vehicle body panels, from the viewpoint of reducing the number of steps and costs in the vehicle body manufacturing process, it is preferable to cure (thermally cure) the adhesive composition by utilizing the heat of a paint drying oven at the same time as baking the electrodeposition coating in the paint drying oven in the electrodeposition coating process carried out after the vehicle body assembly process in which the adhesive composition is applied and the vehicle body panels are assembled, and therefore a latent curing agent that exhibits a curing action when heated is preferably used. Among latent curing agents, dicyandiamide is more preferred, and when dicyandiamide is used, it is preferable to use a curing accelerator (e.g., tertiary amine, imidazole, urea derivative, etc.) in combination to accelerate curing.

[0043] Examples of catalysts include amines (e.g., 3-(3,4-dichlorophenyl)-N,N-dimethylurea (DCMU), tertiary amines, monoethylamine trifluoride, amine complexes such as amine trichloride complexes, amine adduct compounds, etc.), imidazoles (e.g., 2-peptadecylimidazole (C17Z), 2-undecylimidazole (C11Z), 2-phenylimidazole (2PZ), 1,2-dimethylimidazole (1,2DMZ), 2-phenyl-4-methylimidazole, imidazole adduct compounds, etc.), and the like. ), hydrazide compounds (e.g., adipic acid dihydrazide, dodecanedioic acid dihydrazide), urea compounds (e.g., urea derivatives such as 1,1'-(4-methyl-1,3-phenylene)bis(3,3-dimethylurea), phenyl-dimethylurea, methylene-diphenyl-bisdimethylurea, 3-phenyl-1,1-dimethylurea, and 3-(3-chloro-4-methylphenyl)-1,1-dimethylurea, and phenyldimethylurea (PDMU)), phosphines such as triphenylphosphine, phosphonium salts, and polyamide resins. These may be used alone or in combination of two or more.

[0044] Commercially available products of such curing agents and curing accelerators include, for example, DICY7, 15, 2, 7A, and CVC Thermoset manufactured by Mitsubishi Chemical Corporation and Japan Epoxy Resin Co., Ltd. Specialties' Omicure DDA10, DDA50, DDA100, DDA5, CG-325, DICY-F, DICY-M, DICYNEX325, Air Products Japan Co., Ltd.'s CG-1200, CG-1400, Alzchem's Dicyandiamide, Oxalis Chemicals Co., Ltd.'s Epicure (registered trademark) 108, 8537-WY60, 8536MY-69, 8290-Y-60, Mitsubishi Chemical Corporation's Epicure (registered trademark) 3010, Shikoku Chemicals Corporation's imidazole compounds PZ, 2PHZ, 2P4MHZ, C17Z, 2E4MZ, TBZ, 2MA-OK, Ajinomoto Phi Examples of such anti-inflammatory agents include, but are not limited to, Amicure (registered trademark) PN23, 31, 50, PN40J, MY24, and MY-H from Ntechno Corporation, EH-3293S, EH-3366S, EH-3615S, EH-4070S, 4342S, and 3731S from ADEKA Corporation, Novacure (registered trademark) HX-3742 and 3721 from Asahi Kasei Chemicals Corporation, FXE-1000, FXR-1030, 1080, and 1110 from Fuji Chemical Industry Co., Ltd., Dyhard UR200, 300, 400, 500, 700, and 800 from Alzchem, and Dyhard MI-C, MIFF, PI, PI-FF, and MI-A5.

[0045] The amount of curing agent to be added is determined appropriately depending on the epoxy resin used (epoxy equivalent, amount added, etc.) and curing conditions. For example, in the case of amines such as imidazole compounds, dialkyl urea derivatives, and dicyandiamide, the amount is determined based on the amine equivalent and epoxy equivalent. For example, the amount is 1 to 20 parts by mass, preferably 1 to 15 parts by mass, and more preferably 2 to 10 parts by mass, per 100 parts by mass of the total epoxy resin. In the case of polyaddition-type curing agents such as other hydrazide derivatives, the amount is added in an amount equivalent to the active hydrogen equivalent per 1 equivalent of the total epoxy. In the case of catalyst-type curing agents, the amount is, for example, 0.3 to 10 parts by mass, preferably 0.5 to 8 parts by mass, and more preferably 0.6 to 5 parts by mass, per 100 parts by mass of the total epoxy resin.

[0046] The epoxy-based reactive diluent has an epoxy group in its molecule and is incorporated into part of the network structure of the resin during the curing process of the epoxy resin. In this embodiment, a monofunctional reactive (monofunctional group) reactive diluent and / or a bifunctional reactive (bifunctional group) reactive diluent is used.

[0047] Monofunctional reactive epoxy-based reactive diluents include glycidyl ether-type compounds derived from epichlorohydrin and having one epoxy group in the molecule, such as higher alcohol glycidyl ethers (e.g., C12,14 mixtures, C12,13 mixtures, C12-14 mixtures, etc.), n-butanol glycidyl ether, hexyl glycidyl ether, 2-ethylhexyl glycidyl ether, butyl glycidyl ether, phenyl glycidyl ether, butylphenyl glycidyl ether, p-tert-butylphenyl glycidyl ether, cresyl glycidyl ether, allyl glycidyl ether, tetrahydrofurfuryl glycidyl ether, furfuryl glycidyl ether, trimethoxysilyl glycidyl ether, and methacrylic acid glycidyl ester. These may be used alone or in combination of two or more. Preferred are those having an aromatic group, for example, aromatic backbone monoepoxides such as phenyl glycidyl ether, p-tert-butylphenyl glycidyl ether, and 3-pentadecadienylphenol glycidyl ether, and higher alcohol monoepoxides such as alkyl monoglycidyl ether. This allows for increased damping with minimal loss of rigidity. In the case of a linear higher alcohol epoxy-based reactive diluent such as a linear higher alcohol monoepoxide, the glass transition temperature (T g ) and increase the loss factor (tan δ) at room temperature, improving damping. Aromatic backbone epoxy-based reactive diluents such as aromatic backbone monoepoxides can increase the elastic modulus and improve rigidity. Furthermore, the monofunctional reactive epoxy-based reactive diluent preferably has a viscosity (mPa·s / 25°C) in the range of 5 to 40 and an epoxy equivalent (g / eq) in the range of 100 to 400.

[0048] Commercially available monofunctional reactive diluents include, for example, DY-BP, OPP-EP, TD-EX, Epogosey (registered trademark) ML, 2EH, LA, and OCR from Yokkaichi Chemical Co., Ltd., ADEKA Glycirol ED-502, 502S, 509E, 509S, and 529 from ADEKA Corporation, EPOTEC (registered trademark)-RD108, 110, 118, 104, 105, 106, 136, 138, and 137 from Tomoe Engineering Co., Ltd., EPIOL (registered trademark) B, EH-N, A, P, and TB from NOF Corporation, YED11N and 188 from Mitsubishi Chemical Corporation, and NPEK-041 and 048 from NAN YA PLASTICS CORPOTATION.

[0049] Bifunctional epoxy-based reactive diluents include glycidyl ether-type compounds derived from epichlorohydrin and having two epoxy groups per molecule, such as 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, trimethylolpropane triglycidyl ether, neopentyl glycol glycidyl ether, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, polytetramethylene glycol diglycidyl ether, and dimer acid diglycidyl ester. Preferred are polypropylene glycol-based diepoxides, such as polyoxyalkylene glycol diglycidyl ether, and those with an aliphatic skeleton (alkyl group), such as aliphatic skeleton diepoxides such as 1,6-hexanediol glycidyl. This allows for improved damping with minimal loss of rigidity. Epoxy-based reactive diluents with a glycol structure, such as polypropylene glycol diepoxides, have a high glass transition temperature (T g) and increase the loss factor (tan δ) at room temperature, improving damping. Aliphatic skeleton epoxy-based reactive diluents such as aliphatic skeleton diepoxides can improve the elastic modulus. Furthermore, the bifunctional reactive (monofunctional reactive) epoxy-based reactive diluent preferably has a viscosity (mPa·s / 25°C) in the range of 5 to 40 and an epoxy equivalent (g / eq) in the range of 100 to 400. More preferably, it has a viscosity (mPa·s / 25°C) in the range of 10 to 80 and an epoxy equivalent (g / eq) in the range of 50 to 400.

[0050] Commercially available bifunctional reactive diluents include, for example, Denacol (registered trademark) EX-810, 810P, 811, 850, 851, 830, 832, 841, 861, 201, 211, 212, 252, and 931 from Nagase ChemteX Corporation, DER732 from DOW (registered trademark), Epogosey (registered trademark) PT, PG400, BD, NPG, HD, HD(M), and HD(D) from Yokkaichi Chemical Co., Ltd., YED216M and 216D from Mitsubishi Chemical Corporation, NPER-032 from NAN YA PLASTICS CORPOTATION, and Epiol (registered trademark) 100LC from NOF Corporation.

[0051] By blending such monofunctional or bifunctional reactive epoxy-based reactive diluents, it is possible to make the viscosity and fluidity at the time of application (before curing) appropriate, making it easier to apply. Furthermore, the monofunctional or bifunctional reactive epoxy-based reactive diluents are incorporated into the resin network formation during the curing process of the epoxy resin, and the glass transition temperature (T g ) can be reduced, and the loss factor at room temperature can be increased. Monofunctional reactive epoxy-based reactive diluents have a high viscosity-reducing ability, making it possible to lower the viscosity. In other words, a small amount can effectively reduce the viscosity. Therefore, when a filler is blended, the amount of filler blended can be increased, improving the effect of the filler in imparting properties. In particular, monofunctional reactive epoxy-based reactive diluents have a high viscosity-reducing ability, and adding a small amount can reduce the viscosity of the adhesive composition to a level that makes it easy to apply, and can increase the loss factor at room temperature and improve damping properties without significantly reducing the rigidity of the adhesive (cured film). On the other hand, bifunctional epoxy-based reactive diluents can increase the rigidity of the adhesive (cured film) without significantly reducing the damping property at room temperature. According to the inventors' experimental research, polypropylene glycol-based diepoxides in particular can increase the glass transition temperature (T g ) and improve damping characteristics in the normal temperature range.

[0052] Such an epoxy-based reactive diluent is blended in an amount of 10 to 100 parts by mass, more preferably 15 to 90 parts by mass, and even more preferably 20 to 80 parts by mass, per 100 parts by mass of the main epoxy resin. If the amount of epoxy-based reactive diluent blended is too large, the rigidity cannot be ensured, whereas if the amount of epoxy-based reactive diluent blended is too small, the coatability cannot be ensured and the damping properties at room temperature cannot be ensured. Within the above range, it is possible to ensure good application properties while achieving both high damping properties and high rigidity. The amount of the epoxy-based reactive diluent is, for example, 1 to 50 parts by mass, preferably 2 to 40 parts by mass, more preferably 3 to 30 parts by mass, and even more preferably 4 to 40 parts by mass, relative to 100 parts by mass of the total amount of the adhesive composition.

[0053] Furthermore, the damping adhesive composition of the present embodiment preferably contains a coumarone resin. Coumarone resins contain coumarone residues in their skeletal structure, i.e., contain structural units derived from coumarone-based monomers. Examples of such copolymers include coumarone (1-benzofuran) polymers and copolymers with indene (CH), styrene (CH), α-methylstyrene, methylindene, methylcoumarone, dicyclopentadiene, or vinyltoluene. These coumarone resins may be used alone or in combination of two or more. Among these, coumarone-indene copolymers containing structural units derived from indene-based monomers, or coumarone-indene-styrene copolymers containing structural units derived from indene-based monomers and structural units derived from styrene-based monomers, are preferred.

[0054] The coumarone resin preferably has a phenol group at its terminal, more preferably an aromatic structure having a phenolic hydroxyl group. For example, the hydroxyl value (mgKOH / g) is in the range of 35 to 80, preferably 45 to 70. This improves compatibility with epoxy resins, enabling increased rigidity and damping. Furthermore, the coumarone resin is preferably liquid at room temperature, and has a viscosity (mPa·s / 25°C) within the range of, for example, 100 to 4000, preferably 200 to 3000, more preferably 300 to 2500, and even more preferably 450 to 2300. This makes it possible to improve damping properties and rigidity without impairing coatability. In addition, the coumarone resin has a mass average molecular weight (Mw) in the range of, for example, 50 to 750, preferably 100 to 500, or more preferably 150 to 300. This improves dispersibility in the adhesive composition.

[0055] When coumarone resin is added, it is preferably added in an amount of 5 to 80 parts by mass, more preferably 10 to 70 parts by mass, and even more preferably 20 to 60 parts by mass, relative to 100 parts by mass of the main epoxy resin. This makes it possible to improve damping and rigidity without impairing applicability. The amount is, for example, within the range of 1 to 20 parts by mass, preferably 2 to 15 parts by mass, more preferably 3 to 12 parts by mass, and even more preferably 5 to 10 parts by mass relative to 100 parts by mass of the total amount of the adhesive composition.

[0056] Commercially available coumarone resins include, for example, Nitto Chemical Co., Ltd.'s Knit Resin (registered trademark) Coumarone L-5, L-20, G-90, G-120, and G-120S; Rutgers Chemicals AG's NOVARES (registered trademark) C series (Novares C10, C30, C70, C80, C90, C100, and C120) and CA series (Novares CA80, CA100, and CA120); NATRO-REZ (registered trademark) 10, 25, and 50; and Kobe Oil Chemical Industry Co., Ltd.'s Process Resin.

[0057] Furthermore, when carrying out the present invention, other materials may be used depending on the intended use, desired properties, etc., such as fillers (heavy calcium carbonate, talc, calcium silicate, aluminum hydroxide, calcium hydroxide, magnesium hydroxide, alumina, zircon, graphite, barium sulfate, clay, mica, kaolin, wollastonite, mica, feldspar, syenite, chlorite, bentonite, montmorillonite, barite, cristobalite, dolomite, quartz, diatomaceous earth, aluminum silicate, barium carbonate, magnesium carbonate, zinc carbonate, mineral fibers, textile fibers, glass fibers, aramid pulp, boron fibers, carbon fibers, phosphates, silica such as crystalline silica, amorphous silica, fused silica, fumed silica, calcined silica, precipitated silica, and pulverized (fine powder) silica, pyrophyllite, silica sand, cellulose, cement, and resin powders such as polyethylene, calcium oxide, iron oxide, and zinc oxide. It is also possible to blend in additives such as titanium oxide, barium oxide, magnesium oxide (magnesia), titanium dioxide, hollow ceramic beads, hollow glass beads, and other hollow inorganic beads, hollow organic beads made of polyester resin, glass beads, metal powder, bitumen, etc.), thixotropic agents (also called thixotropy-imparting agents; for example, colloidal calcium carbonate (fine calcium carbonate), silica, carbon black such as Ketjen Black, sepiolite, and colloidal hydrated aluminum silicate / organic complexes), plasticizers (for example, phthalic acid-based), pigments, dyes, colorants, defoamers, leveling agents, tackifiers (adhesion-imparting agents), flame retardants, catalysts, reaction retarders, antioxidants, antioxidants, antistatic agents, conductivity-imparting agents, lubricants, agents for imparting sliding properties, ultraviolet absorbers, surfactants, dispersants, dispersion stabilizers, dehydrating agents, crosslinking agents, rust inhibitors, solvents, thermosetting resins other than epoxy resins, and thermoplastic resins.

[0058] When a filler is blended, the blending amount of the filler is within the range of, for example, 10 to 700 parts by mass, preferably 50 to 600 parts by mass, and more preferably 100 to 500 parts by mass relative to 100 parts by mass of the main epoxy resin. When a thixotropic agent is added, the amount of the thixotropic agent added is within the range of, for example, 1 to 80 parts by mass, preferably 3 to 50 parts by mass, and more preferably 5 to 40 parts by mass relative to 100 parts by mass of the main epoxy resin. When the damping adhesive composition is applied as a structural adhesive for automobiles, etc., the viscosity characteristics are adjusted taking into consideration suitability for the production line of automobiles, etc., such as curing characteristics such as curing time and curing temperature, workability, applicability, storage stability, etc.

[0059] The damping adhesive composition of the present embodiment is prepared by uniformly mixing and stirring the ingredients using a known mixer / disperser, such as a planetary mixer, a disperser, a Henschel mixer, a kneader, an ink roll, an extruder, or a change can mixer. The prepared attenuation adhesive composition is then applied to the adherend by a known method, such as spraying, using a sealer gun, or brushing. The composition may be formulated to be applied warm (for example, at about 35°C to 40°C).

[0060] According to a damping adhesive composition containing one or more main epoxy resins selected from the group consisting of glycidyl ether-type epoxy resins, glycidyl ester-type epoxy resins, and glycidyl amine-type epoxy resins, a flexible epoxy resin, a monofunctional or bifunctional reactive epoxy-based reactive diluent, and a curing agent, the combination of the main epoxy resin, the flexible epoxy resin, and the monofunctional or bifunctional reactive epoxy-based reactive diluent can increase the loss factor (tan δ) over a wide temperature range, including room temperature, without significantly impairing the elastic modulus, thereby ensuring both damping properties and rigidity. Preferably, the rubber further contains coumarone resin, which can increase damping and rigidity, thereby achieving both high damping and high rigidity.

[0061] The damping adhesive composition of the present embodiment can be used, for example, as an adhesive for structural components in automobiles, Shinkansen trains, electric trains, and other vehicles, ships, aircraft, and the aerospace industry. It is particularly useful as a structural adhesive for automobiles, such as roof rails and various pillars, as well as for spot-welded components and components such as hemmed joints between inner and outer panels of doors, hoods, and trunk lids, wheel arches, side sills, and outer sills. The term "structural adhesive" refers to a highly reliable adhesive (JIS K6800) that exhibits minimal deterioration in adhesive properties even under heavy loads for extended periods of time. The damping adhesive composition of the present embodiment can achieve both rigidity and damping properties. Therefore, when applied to automobiles, for example, it can attenuate and reduce vehicle body vibrations and solid-borne noise while minimizing increases in mass. By ensuring damping properties, the vehicle's NVH performance can be improved, and by ensuring rigidity, the vehicle's handling stability can be improved.

[0062] That is, the damping adhesive composition of this embodiment can achieve both rigidity and damping properties, and therefore, when used as a structural adhesive for body panels of vehicles such as automobiles, it can improve the handling stability and ride comfort of automobiles and reduce noise and vibration, such as road noise. In particular, when vibration damping is imparted by adding reinforcing members or increasing the thickness of the panels to be joined, the increased weight makes it impossible to reduce the vehicle body weight. However, by achieving both rigidity and damping properties in a structural adhesive composition used to join body panels and frames, which correspond to the vibration transmission and response systems, it is possible to improve the vibration damping of the vehicle body without increasing the vehicle weight. In other words, it is possible to achieve both weight reduction and ride comfort.

[0063] In the damping adhesive composition of this embodiment, when the curing agent for the epoxy resin is a latent curing agent, the composition is cured by heating. For example, when the damping adhesive composition is used as a structural adhesive and the adherend to which it is applied is a structural member of a vehicle body, the adhesive composition is applied to a vehicle body panel, and then the vehicle body assembly process, vehicle body washing process, vehicle body surface treatment process, and vehicle body electrodeposition coating process are carried out in that order. After electrodeposition coating is applied, the process involves baking the electrodeposition coating in a paint drying oven. During this baking process, the adhesive composition is heat-cured by the heat of the paint drying oven (for example, at a temperature of about 120°C to about 220°C, preferably about 150°C to about 200°C, for example, for about 10 to 60 minutes, preferably about 20 to 60 minutes).

[0064] Furthermore, when the epoxy resin curing agent is a latent curing agent, it is a one-component thermosetting epoxy resin system, and since it is a one-component system, there is no laborious measuring and mixing work or restriction of pot life as with two-component mixed systems, and the quality is more stable. Furthermore, it does not take up much storage space.

[0065] [Example] Next, examples of the damping adhesive composition according to the embodiment of the present invention will be described. The damping adhesive compositions of Examples 1 to 4 contain a bisphenol A liquid epoxy resin (DGEBA), which is a glycidyl ether type epoxy resin, as the main epoxy resin; polypropylene bisphenol A diglycidyl ether (diglycidyl ether of a propylene oxide adduct of bisphenol A), which is a bisphenol alkylene oxide-modified epoxy resin, as the flexible epoxy resin; alkyl (C12-C13) monoglycidyl ether, which is a linear higher alcohol monoepoxide, as the monofunctional reactive epoxy diluent; or polyoxyalkylene glycol glycidyl ether, which is an aliphatic skeleton diepoxide, as the bifunctional reactive epoxy diluent; dicyandiamide (DICY), a tertiary amine adduct type latent curing agent, and 3,4-dichlorophenyl-1,1-dimethylurea (DCMU) as the curing agent / curing accelerator; heavy calcium carbonate and calcium oxide as fillers; and silica as a thixotropic agent. In Examples 1 to 3, in addition to the above materials, a coumarone-indene-styrene copolymer having a terminal hydroxyl group was further contained as a coumarone resin. In Examples 1 to 4, these materials were mixed at room temperature using a universal mixer until uniform, and then degassed to obtain a damping adhesive composition.

[0066] For comparison, an adhesive composition according to a comparative example was also prepared. Comparative Example 1 does not contain any flexible epoxy resin, but contains the same materials as in Example 1. In Comparative Example 2, a trifunctional reactive epoxy-based reactive diluent was used instead of the monofunctional or difunctional reactive epoxy-based reactive diluent, and the other materials were the same as those in Example 1. Comparative Example 3 does not contain the flexible epoxy resin and the coumarone resin, but contains the same materials as in Example 1. The blending compositions of Examples 1 to 4 and Comparative Examples 1 to 3 are shown in the upper part of Table 1. The blending compositions shown in the upper part of Table 1 are in parts by mass.

[0067] [Table 1]

[0068] As shown in Table 1, the damping adhesive composition of Example 1 contains 100 parts by weight of bisphenol A liquid epoxy resin as the main epoxy resin, 44 parts by weight of polypropylene bisphenol A diglycidyl ether as the flexible epoxy resin, 31 parts by weight of alkyl (C12-C13) monoglycidyl ether as a monofunctional reactive epoxy diluent, 44 parts by weight of coumarone-indene-styrene copolymer B as the coumarone resin with a viscosity of 2000 mPa·S, a hydroxyl value of 65 mgKOH / g, and an average molecular weight MW of 220, 11 parts by weight of a tertiary amine adduct latent curing agent, 3 parts by weight of DICY, and 1 part by weight of DCMU as the curing agent / curing accelerator, 313 parts by weight of heavy calcium carbonate and 16 parts by weight of calcium oxide as fillers, and 13 parts by weight of silica as a thixotropic agent.

[0069] The damping adhesive composition of Example 2 contains 100 parts by weight of bisphenol A liquid epoxy resin as the main epoxy resin, 44 parts by weight of polypropylene bisphenol A diglycidyl ether as the flexible epoxy resin, 31 parts by weight of polyoxyalkylene glycol glycidyl ether as a bifunctional reactive epoxy diluent, 44 parts by weight of coumarone-indene-styrene copolymer B as the coumarone resin with a viscosity of 2000 mPa·S, a hydroxyl value of 65 mgKOH / g, and an average molecular weight MW of 220, 11 parts by weight of a tertiary amine adduct latent curing agent, 3 parts by weight of DICY, and 1 part by weight of DCMU as the curing agent / curing accelerator, 313 parts by weight of heavy calcium carbonate and 16 parts by weight of calcium oxide as fillers, and 13 parts by weight of silica as a thixotropic agent.

[0070] The damping adhesive composition of Example 3 contains 100 parts by weight of bisphenol A liquid epoxy resin as the main epoxy resin, 44 parts by weight of polypropylene bisphenol A diglycidyl ether as the flexible epoxy resin, 31 parts by weight of alkyl (C12-C13) monoglycidyl ether as a monofunctional reactive epoxy diluent, 44 parts by weight of coumarone-indene-styrene copolymer A as a coumarone resin with a viscosity of 500 mPa·S, a hydroxyl value of 50 mgKOH / g, and an average molecular weight MW of 160, 11 parts by weight of a tertiary amine adduct latent curing agent, 3 parts by weight of DICY, and 1 part by weight of DCMU as curing agents and curing accelerators, 313 parts by weight of heavy calcium carbonate and 16 parts by weight of calcium oxide as fillers, and 13 parts by weight of silica as a thixotropic agent.

[0071] The damping adhesive composition of Example 4 was a blend of 100 parts by mass of bisphenol A liquid epoxy resin as the main epoxy resin, 44 parts by mass of polypropylene bisphenol A diglycidyl ether as the flexible epoxy resin, 75 parts by mass of alkyl (C12-C13) monoglycidyl ether as a monofunctional reactive epoxy-based reactive diluent, 11 parts by mass of a tertiary amine adduct-type latent curing agent, 3 parts by mass of DICY, and 1 part by mass of DCMU as curing agents and curing accelerators, 313 parts by mass of heavy calcium carbonate and 16 parts by mass of calcium oxide as fillers, and 13 parts by mass of silica as a thixotropic agent.

[0072] The adhesive composition of Comparative Example 1 contained 144 parts by mass of a bisphenol A liquid epoxy resin as the main epoxy resin, 31 parts by mass of an alkyl (C12-C13) monoglycidyl ether as a monofunctional reactive epoxy diluent, 44 parts by mass of a coumarone resin (coumarone-indene-styrene copolymer B) with a viscosity of 2000 mPa·S, a hydroxyl value of 65 mgKOH / g, and an average molecular weight MW of 220, 11 parts by mass of a tertiary amine adduct latent curing agent, 3 parts by mass of DICY, and 1 part by mass of DCMU as curing agents and curing accelerators, 313 parts by mass of heavy calcium carbonate and 16 parts by mass of calcium oxide as fillers, and 13 parts by mass of silica as a thixotropic agent, but did not contain any flexible epoxy resin.

[0073] The damping adhesive composition of Comparative Example 2 contained 100 parts by mass of a bisphenol A type liquid epoxy resin as a main epoxy resin, 44 parts by mass of polypropylene bisphenol A diglycidyl ether as a flexible epoxy resin, 31 parts by mass of a mixture of trimethylolpropane triglycidyl ether, trimethylolpropane diglycidyl ether, and trimethylolpropane monoglycidyl ether as a trifunctional reactive epoxy-based reactive diluent, and a coumarone resin having a viscosity of 2000 mPa·S and a hydroxyl value of 65 mgKOH / g. It contains 44 parts by mass of coumarone-indene-styrene copolymer B with an average molecular weight MW of 220, 11 parts by mass of a tertiary amine-based amine adduct type latent curing agent as a curing agent / curing accelerator, 3 parts by mass of DICY, and 1 part by mass of DCMU, 313 parts by mass of heavy calcium carbonate and 16 parts by mass of calcium oxide as fillers, and 13 parts by mass of silica as a thixotropic agent, and instead of the monofunctional or difunctional epoxy-based reactive diluent used in the examples, a trifunctional epoxy-based reactive diluent is used.

[0074] The adhesive composition of Comparative Example 3 contained 144 parts by mass of a bisphenol A liquid epoxy resin as the main epoxy resin, 75 parts by mass of an alkyl (C12-C13) monoglycidyl ether as a monofunctional reactive epoxy-based reactive diluent, 11 parts by mass of a tertiary amine-based amine adduct latent curing agent, 3 parts by mass of DICY, and 1 part by mass of DCMU as curing agents and curing accelerators, 313 parts by mass of heavy calcium carbonate and 16 parts by mass of calcium oxide as fillers, and 13 parts by mass of silica as a thixotropic agent, and did not contain a flexible epoxy resin or a coumarone resin.

[0075] The one-component thermosetting adhesive compositions prepared in Examples 1 to 4 and Comparative Examples 1 to 3 were evaluated for damping property and rigidity by measuring the loss factor (tan δ), which is an index of damping property, and the modulus of elasticity (Young's modulus), which is an index of rigidity. In addition, the shear strength was also measured and evaluated.

[0076] (Measurement and evaluation of loss factor (tanδ)) The one-component thermosetting adhesive compositions of each Example and Comparative Example were heated (baking conditions: 170°C x 20 minutes) to prepare cured adhesive samples (2 mm thick). These samples were then cut to fit a dynamic viscoelasticity measurement (DMA) instrument (DMAQ800 manufactured by TA Instruments), and the loss factor (tanδ) was measured using the DMA instrument. The measurement conditions were a single cantilever fixture, a strain of 0.05%, a heating rate of 1°C / min, and a measurement temperature of 10 to 70°C. Tanδ at 20°C measured under these conditions was evaluated as ⊚ if it was 0.15 or greater, ◯ if it was 0.10 or greater but less than 0.15, and × if it was less than 0.10. Furthermore, tanδ at 40°C measured under these conditions was evaluated as ⊚ if it was 0.40 or greater, ◯ if it was 0.30 or greater but less than 0.40, and × if it was less than 0.30. Furthermore, if tan δ at 60° C. measured under the above conditions was 0.40 or more, it was judged as ⊚; if it was 0.30 or more but less than 0.40, it was judged as ◯; and if it was less than 0.30, it was judged as x.

[0077] (Measurement and evaluation of elastic modulus) The adhesive compositions of each Example and Comparative Example were heated (baking conditions: 170°C x 20 minutes) to prepare cured adhesives (2 mm thick). These were then cut into ASTM No. 1 dumbbell shapes (ASTM D638). Measurements were performed at room temperature at a rate of 1 mm / min using an autograph (equipped with a contact or non-contact extensometer). The Young's modulus (elastic modulus) was calculated from the SS curve (stress-strain curve) obtained by the measurements using linear regression (in accordance with JIS K-7161-1:2014). A calculated elastic modulus of 1.0 GPa or greater was evaluated as ⊚, a value of 0.5 GPa or greater but less than 1.0 GPa was evaluated as ◯, and a value of less than 0.5 GPa was evaluated as ×.

[0078] (Shear strength measurement and evaluation) Shear strength was measured in accordance with JIS K6850. Specifically, adhesive test specimens were prepared using the adhesive compositions of each Example and Comparative Example, and then a tensile shear adhesive strength test was performed to measure shear strength (shear adhesive strength). Specifically, two 10 mm × 100 mm × 1.6 mm steel plates were prepared as test panels. Each adhesive composition was applied to one panel at a thickness of 0.15 mm over a 10 mm length from one end of the longitudinal direction. One end of the other panel was then placed on the coated surface and linearly bonded (adhesive layer between the joints of both panels: 10 mm × 10 mm × 0.15 mm thick). Each adhesive composition was then heat-cured in a hot air oven at 170°C for 30 minutes to prepare adhesive test specimens bonded via a fully cured adhesive layer. Both ends of this adhesive specimen were pulled in the longitudinal direction at a pulling rate of 10 mm / min using a tensile tester (Shimadzu Corporation), and the shear strength was measured at room temperature (20° C.) A shear strength of 15.0 MPa or more was evaluated as ⊚, a shear strength of 3.0 MPa or more but less than 15.0 MPa was evaluated as ◯, and a shear strength of less than 3.0 MPa was evaluated as ×. The measured values ​​and evaluation results of the loss factor (tan δ), modulus of elasticity, and shear strength are shown in the lower part of Table 1.

[0079] As shown in Table 1, in Comparative Example 1, both the elastic modulus and shear strength were rated as ◎, and the loss factor (tan δ) at 60°C was also rated as ◎. However, because no flexible epoxy resin was blended, the loss factors (tan δ) at 20°C and 40°C were low and rated as ×. In Comparative Example 2, both the modulus of elasticity and shear strength were rated as ◎, and the loss coefficient (tan δ) at 60°C was also rated as ◎. However, because a trifunctional reactive epoxy diluent was used instead of a mono- or difunctional reactive epoxy diluent, the loss coefficients (tan δ) at 20°C and 40°C were low and rated as ×. In Comparative Example 3, which does not contain flexible epoxy resin or coumarone resin, the elastic modulus is rated as ◎, the shear strength is rated as ○, and the loss coefficient (tan δ) at 60°C is rated as ◎, but the loss coefficients (tan δ) at 20°C and 40°C are low and are rated as ×.

[0080] In contrast, the damping adhesive compositions of Examples 1 to 4, which contained a bisphenol A liquid epoxy resin, which is a glycidyl ether epoxy resin, as the main epoxy resin, a polyoxyalkylene epoxy resin, polypropylene bisphenol A diglycidyl ether (diglycidyl ether of a propylene oxide adduct of bisphenol A), as the flexible epoxy resin, and either an alkyl (C12-C13) monoglycidyl ether, which is a linear higher alcohol monoepoxide, as the monofunctional reactive epoxy reactive diluent or a polyoxyalkylene glycol glycidyl ether, which is an aliphatic skeleton diepoxide, as the bifunctional reactive epoxy reactive diluent, all achieved a rating of ⊚ or ◯ for the loss factor (tan δ) at 20°C, 40°C, and 60°C, a rating of ⊚ or ◯ for the elastic modulus, and a rating of ⊚ or ◯ for the shear strength.

[0081] That is, in Example 1, which contained a bisphenol A liquid epoxy resin, which is a glycidyl ether type epoxy resin, as the main epoxy resin, polypropylene bisphenol A diglycidyl ether (diglycidyl ether of a propylene oxide adduct of bisphenol A), which is a bisphenol alkylene oxide-modified epoxy resin, as the flexible epoxy resin, alkyl (C12-C13) monoglycidyl ether, which is a linear higher alcohol monoepoxide, as the monofunctional reactive epoxy diluent, and coumarone-indene-styrene copolymer B, which has a viscosity of 2000 mPa·S and a hydroxyl value of 65 mgKOH / g, as the coumarone resin, the loss factor (tan δ), elastic modulus, and shear strength at 20°C, 40°C, and 60°C were all rated as ⊚.

[0082] In Example 2, which contained a bisphenol A liquid epoxy resin, which is a glycidyl ether type epoxy resin, as the main epoxy resin, polypropylene bisphenol A diglycidyl ether (diglycidyl ether of a propylene oxide adduct of bisphenol A), which is a bisphenol alkylene oxide-modified epoxy resin, as the flexible epoxy resin, polyoxyalkylene glycol glycidyl ether, which is an aliphatic skeleton diepoxide, as the bifunctional reactive epoxy-based reactive diluent, and coumarone-indene-styrene copolymer B, which has a viscosity of 2000 mPa·S and a hydroxyl value of 65 mgKOH / g, as the coumarone resin, the loss factor (tanδ) at 40°C and 60°C, elastic modulus, and shear strength were all rated as ◎, but only the loss factor (tanδ) at 20°C was rated as ◯.

[0083] In Example 3, which contained a bisphenol A liquid epoxy resin that is a glycidyl ether type epoxy resin as the main epoxy resin, polypropylene bisphenol A diglycidyl ether (diglycidyl ether of a propylene oxide adduct of bisphenol A) that is a bisphenol alkylene oxide-modified epoxy resin as the flexible epoxy resin, alkyl (C12-C13) monoglycidyl ether that is a linear higher alcohol monoepoxide as the monofunctional reactive epoxy-based reactive diluent, and coumarone-indene-styrene copolymer A that has a viscosity of 500 mPa·S, a hydroxyl value of 50 mgKOH / g, and an average molecular weight MW of 160 as the coumarone resin, the loss factor (tan δ) and shear strength at 20°C, 40°C, and 60°C were all rated as ◎, but only the elastic modulus was rated as ◯.

[0084] In Example 4, which contained a bisphenol A liquid epoxy resin that is a glycidyl ether epoxy resin as the main epoxy resin, polypropylene bisphenol A diglycidyl ether (diglycidyl ether of a propylene oxide adduct of bisphenol A) that is a bisphenol alkylene oxide-modified epoxy resin as the flexible epoxy resin, and alkyl (C12-C13) monoglycidyl ether that is a linear higher alcohol monoepoxide as the monofunctional reactive epoxy-based reactive diluent, and which did not contain a coumarone resin, the loss factor (tan δ) at 20°C was rated as Excellent, and the loss factor (tan δ) at 40°C and 60°C, the elastic modulus, and the shear strength were all rated as Good.

[0085] Therefore, the damping adhesive composition of this example can exhibit damping properties over a wide temperature range, including room temperature, and can also ensure rigidity.

[0086] Furthermore, from the comparison between Example 1 and Comparative Example 1, and the comparison between Example 1 and Comparative Example 2, it is presumed that the combination of a main epoxy resin such as a bisphenol-type epoxy resin, a flexible epoxy resin such as a bisphenol alkylene oxide-modified epoxy resin, and a monofunctional reactive epoxy-based diluent such as a linear higher alcohol-type monoepoxide or a bifunctional reactive epoxy-based diluent such as an aliphatic skeleton diepoxide makes it possible to exhibit damping properties over a wide temperature range, including room temperature. That is, in the case of the main epoxy resin such as bisphenol type epoxy resin, the glass transition temperature (T g ) is high (for example, 80°C to 150°C), the loss factor (tanδ) can be increased in a temperature range (for example, 50°C to 130°C) higher than room temperature (15°C to 25°C) by blending the main epoxy resin. In addition, flexible epoxy resins such as bisphenol alkylene oxide modified epoxy resins have a higher glass transition temperature (T g ) is low, and furthermore, by blending monofunctional reactive epoxy-based diluents such as linear higher alcohol monoepoxides or bifunctional reactive epoxy-based diluents such as aliphatic skeleton diepoxides, the glass transition temperature (T g It is believed that by lowering the modulus of elasticity, the loss factor (tan δ) at room temperature can be increased by blending a flexible epoxy resin such as a bisphenol alkylene oxide-modified epoxy resin with a monofunctional reactive epoxy diluent such as a linear higher alcohol monoepoxide or a bifunctional reactive epoxy diluent such as an aliphatic skeleton diepoxide. Generally, the elastic modulus and the loss factor (tan δ) are inversely related. However, the combination of a main epoxy resin such as a bisphenol epoxy resin, a flexible epoxy resin such as a bisphenol alkylene oxide-modified epoxy resin, and a monofunctional reactive epoxy diluent such as a linear higher alcohol monoepoxide or a bifunctional reactive epoxy diluent such as an aliphatic skeleton diepoxide can increase the loss factor (tan δ) over a wide temperature range, including room temperature, without significantly reducing the elastic modulus, thereby achieving both damping and rigidity.

[0087] In particular, in Example 1, which used a linear alcohol monoepoxide as the monofunctional reactive epoxy-based reactive diluent, the loss factor (tan δ) at 20°C was rated as Excellent, whereas in Example 2, which used a glycol-skeleton diepoxide as the bifunctional reactive epoxy-based reactive diluent, the loss factor (tan δ) at 20°C was rated as Excellent, meaning that Example 1 has a higher loss factor (tan δ) at 20°C than Example 2. On the other hand, although Example 2 has a slightly higher modulus of elasticity, both are rated as Excellent. Therefore, by using a linear alcohol-type epoxy-based reactive diluent as a monofunctional reactive epoxy-based reactive diluent, the loss factor (tan δ) at room temperature can be increased and damping can be improved without significantly reducing rigidity, thereby achieving both high rigidity and high damping.

[0088] Furthermore, it is preferable to further blend coumarone resin from a comparison between Examples 1 to 3 and Example 4. Blending coumarone resin makes it possible to improve the loss factor (tan δ), elastic modulus, and shear strength.

[0089] In particular, in Example 1, in which coumarone-indene-styrene copolymer B having a viscosity of 2000 mPa·S and a hydroxyl value of 65 mgKOH / g was used as the coumarone resin, the loss factor (tanδ) was rated as ⊚ and the elastic modulus was rated as ⊚ at all temperatures of 20°C, 40°C, and 60°C, whereas in Example 3, in which coumarone-indene-styrene copolymer A having a viscosity of 500 mPa·S and a hydroxyl value of 50 mgKOH / g was used as the coumarone resin, the loss factor was rated as ⊚ at all temperatures of 20°C, 40°C, and 60°C. In Example 1, in which the loss factor (tan δ) was rated as Excellent but the elastic modulus was rated as Good, and in which coumarone-indene-styrene copolymer B, which had a viscosity of 2000 mPa·S and a hydroxyl value of 65 mgKOH / g, was used as the coumarone resin, the elastic modulus was higher without a significant decrease in loss factor (tan δ) compared to Example 2, in which coumarone-indene-styrene copolymer A, which had a viscosity of 500 mPa·S and a hydroxyl value of 50 mgKOH / g, was used as the coumarone resin. Therefore, a comparison between Example 1 and Example 3 shows that a coumarone resin with a hydroxyl value of 55 mg KOH / g or more and 70 mg KOH / g or less can increase the elastic modulus without significantly decreasing the loss factor (tan δ), thereby achieving both high rigidity and high damping properties.

[0090] According to experimental research by the present inventors, the blending amount of polypropylene bisphenol A diglycidyl ether as the flexible epoxy resin is preferably in the range of 5 to 80 parts by mass per 100 parts by mass of the bisphenol A liquid epoxy resin as the main epoxy resin. Within this range, it is possible to achieve both high damping properties and high rigidity. The blending amount is more preferably in the range of 10 to 70 parts by mass, and even more preferably in the range of 20 to 60 parts by mass.

[0091] The blending amount of the linear alcohol monoepoxide as a monofunctional reactive epoxy-based diluent or the glycol-skeleton diepoxide as a difunctional reactive epoxy-based diluent is preferably within the range of 10 to 100 parts by mass per 100 parts by mass of the bisphenol A liquid epoxy resin as the main epoxy resin. Within this range, high damping properties and high rigidity can be achieved while ensuring good application properties. The blending amount is more preferably within the range of 15 to 90 parts by mass, and even more preferably within the range of 20 to 80 parts by mass.

[0092] Furthermore, the amount of coumarone-indene-styrene copolymer as the coumarone resin is preferably within a range of 5 to 80 parts by mass per 100 parts by mass of the bisphenol A liquid epoxy resin as the main epoxy resin. Within this range, damping properties and rigidity can be improved while ensuring coatability. The amount is more preferably within a range of 10 to 70 parts by mass, and even more preferably within a range of 20 to 60 parts by mass.

[0093] As described above, the damping adhesive composition according to the above embodiment contains a flexible epoxy resin, one or more main epoxy resins other than the flexible epoxy resin, which are selected from the group consisting of glycidyl ether epoxy resins, glycidyl ester epoxy resins, and glycidyl amine epoxy resins, a monofunctional or difunctional reactive epoxy-based reactive diluent, and a curing agent. According to the damping adhesive composition of the above embodiment, one or more main epoxy resins selected from the group consisting of glycidyl ether type epoxy resins, glycidyl ester type epoxy resins, and glycidyl amine type epoxy resins are used as the epoxy resin in combination with a flexible epoxy resin, and further a monofunctional reactive type or bifunctional reactive type epoxy diluent is used. By using these combinations, it is possible to ensure both damping properties (loss factor) over a wide temperature range while also ensuring rigidity (elastic modulus), thereby achieving both damping properties and rigidity.

[0094] Furthermore, when coumarone resin is contained, rigidity can be increased without significantly reducing damping property, and both damping property and rigidity can be improved, thereby achieving both high damping property (high loss factor) and high rigidity (high elastic modulus).

[0095] The flexible epoxy resin is preferably a bisphenol alkylene oxide-modified epoxy resin. This allows for increased damping (loss factor) with a small decrease in stiffness (elastic modulus). More preferably, polypropylene bisphenol A diglycidyl ether (diglycidyl ether of a propylene oxide adduct of bisphenol A) is used, allowing for increased damping (loss factor) with a smaller decrease in stiffness (elastic modulus).

[0096] The monofunctional reactive epoxy-based diluent is preferably a linear higher alcohol monoepoxide or an aromatic backbone monoepoxide, which can increase the damping property (loss factor) at room temperature with only a small decrease in stiffness (elastic modulus).

[0097] The bifunctional reactive epoxy-based diluent is preferably a glycol-skeleton diepoxide or an aliphatic-skeleton diepoxide, which can increase stiffness (elastic modulus) with a small decrease in damping (loss factor) at room temperature.

[0098] The amount of flexible epoxy resin blended is preferably in the range of 5 to 80 parts by mass per 100 parts by mass of the main epoxy resin. This allows for both high damping (high loss factor) and high rigidity (high elastic modulus). The amount is more preferably in the range of 10 to 70 parts by mass, and even more preferably in the range of 20 to 60 parts by mass.

[0099] The amount of epoxy-based reactive diluent blended is preferably within a range of 10 to 100 parts by mass per 100 parts by mass of the main epoxy resin. This allows for both high damping properties and high rigidity while ensuring ease of application. The amount is more preferably within a range of 15 to 90 parts by mass, and even more preferably within a range of 20 to 80 parts by mass.

[0100] The amount of coumarone resin blended is preferably within a range of 5 to 80 parts by mass per 100 parts by mass of the main epoxy resin. This allows for both high damping properties and high rigidity while ensuring ease of application. The amount is more preferably within a range of 10 to 70 parts by mass, and even more preferably within a range of 20 to 60 parts by mass.

[0101] Furthermore, the coumarone resin preferably has a phenol group at its terminal, which makes it possible to further increase rigidity without significantly reducing damping properties.

[0102] When practicing the present invention, the composition, ingredients, blending amounts, manufacturing method, etc. of the other parts of the damping adhesive composition are not limited to those of the above embodiment. Furthermore, the numerical values ​​given in the embodiment and examples of the present invention do not all indicate critical values, and some numerical values ​​indicate preferred values ​​suitable for implementation, so slight changes to the above numerical values ​​do not negate the implementation.

Claims

1. A damping adhesive composition comprising one or more main epoxy resins selected from the group consisting of glycidyl ether type epoxy resins, glycidyl ester type epoxy resins, and glycidyl amine type epoxy resins, a flexible epoxy resin, a monofunctional or difunctional reactive epoxy-based reactive diluent, and a curing agent.

2. 10. The damping adhesive composition of claim 1, further comprising a coumarone resin.

3. 2. The damping adhesive composition of claim 1, wherein the flexible epoxy resin is a bisphenol alkylene oxide modified epoxy resin.

4. The damping adhesive composition according to claim 1, wherein the monofunctional reactive epoxy-based reactive diluent is a higher alcohol monoepoxide or an aromatic skeleton monoepoxide.

5. The damping adhesive composition according to claim 1, wherein the bifunctional reactive epoxy-based reactive diluent is a glycol-skeleton diepoxide or an aliphatic-skeleton diepoxide.

6. 2. The damping adhesive composition according to claim 1, wherein the flexible epoxy resin is blended in an amount ranging from 5 to 80 parts by weight per 100 parts by weight of the main epoxy resin.

7. 2. The damping adhesive composition according to claim 1, wherein the epoxy-based reactive diluent is blended in an amount ranging from 10 to 100 parts by weight per 100 parts by weight of the main epoxy resin.

8. 3. The damping adhesive composition according to claim 2, wherein the coumarone resin is blended in an amount ranging from 5 to 80 parts by weight per 100 parts by weight of the main epoxy resin.

9. 3. The damping adhesive composition of claim 2, wherein the coumarone resin has a terminal phenol group.

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