JP2014185256A - Epoxy resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an epoxy resin composition which can be cured at a low temperature in a short time while maintaining adhesiveness and is excellent in storage stability.SOLUTION: The one-component thermosetting epoxy resin composition of the present invention contains: an epoxy resin containing a bisphenol A type epoxy resin and a urethane-modified epoxy resin; a curing agent containing dicyandiamide; a first curing accelerator containing 3,4-dichlorophenyl-1,1-dimethylurea; and a second curing accelerator which contains an imidazole compound containing a triazine ring. The content of the 3,4-dichlorophenyl-1,1-dimethylurea is 5 to 15 pts.mass inclusive based on 100 pts.mass of the epoxy resin. The content of the imidazole compound is 1 to 10 pts.mass inclusive based on 100 pts.mass of the epoxy resin.

Description

  The present invention relates to an epoxy resin composition suitably used as a structural adhesive for vehicles and the like.

  An epoxy resin composition containing an epoxy resin is excellent in workability and excellent electrical properties, heat resistance, adhesion, moisture resistance (water resistance), moldability, and the like of the cured product. Therefore, conventionally, epoxy resin compositions have been applied to various different substrates in the fields of electrical / electronic parts, automobile parts, electrical equipment, fiber reinforced plastics (FRP), sports equipment, structural materials, paints, etc. Widely used as an adhesive for bonding.

  For example, a solid amine surface having a melting point of 50 ° C. or higher is coated with fine powder to achieve both low-temperature curability at about 60 ° C. to 120 ° C. and storage stability. A heat-curable composition has been proposed (see, for example, Patent Document 1). Also, a thermosetting epoxy resin that achieves both low-temperature curability and storage stability by adhering a fine powder with a specific center particle size to the surface of a room-temperature solid curing agent and coating the active groups on the surface. A composition has been proposed (see, for example, Patent Document 2).

International Publication No. 95/26374 JP-A-9-87364

  However, although the epoxy resin composition like patent documents 1 and 2 is compatible with curability at low temperature and storage stability, it takes time to cure.

  Therefore, when used as a structural adhesive, an epoxy resin composition that can be cured at a low temperature in a short time and has excellent storage stability is desired.

  An object of this invention is to provide the epoxy resin composition excellent in sclerosis | hardenability at low temperature and storage stability in view of the said problem.

The present invention includes the following (1) to (5).
(1) an epoxy resin containing a bisphenol A type epoxy resin and a urethane-modified epoxy resin;
A curing agent comprising dicyandiamide;
A first curing accelerator comprising 3,4-dichlorophenyl-1,1-dimethylurea;
A second curing accelerator comprising an imidazole compound containing a triazine ring;
Including
The content of the 3,4-dichlorophenyl-1,1-dimethylurea is 5 parts by mass or more and 15 parts by mass or less with respect to 100 parts by mass of the epoxy resin,
Content of the said imidazole compound is 1 mass part or more and 10 mass parts or less with respect to 100 mass parts of said epoxy resins, The 1 liquid heat-curing type epoxy resin composition characterized by the above-mentioned.
(2) The imidazole compound is 2,4-diamino-6- [2'-methylimidazolyl- (1 ')]-ethyl-s-triazine, 2,4-diamino-6- [2'-ethyl-4 Selected from the group comprising '-methylimidazolyl- (1')]-ethyl-s-triazine and 2,4-diamino-6- [2'-undecylimidazolyl- (1 ')]-ethyl-s-triazine The one-component heat-curable epoxy resin composition according to the above (1), which is one or more.
(3) The one-component heat-curable epoxy resin composition according to the above (1) or (2), wherein at least a part of the surface of the imidazole compound is coated with a coating material.
(4) Any of the above (1) to (3), wherein the coating material is one or more selected from the group comprising an olefin polymer, polystyrene, polyester urethane, acrylic polymer, stearic acid and isocyanate-containing acrylic polymer. One-component heat-curable epoxy resin composition according to any one of the above.
(5) The one-component heat-curable epoxy resin composition according to (3) or (4), wherein the melting point of the coating material is 50 ° C. or higher and 110 ° C. or lower.

  ADVANTAGE OF THE INVENTION According to this invention, the epoxy resin composition excellent in sclerosis | hardenability at low temperature and storage stability can be provided.

FIG. 1 is a perspective view of a test piece for a peel test.

  The present invention will be described in detail below. The present invention is not limited by the following modes for carrying out the invention (hereinafter referred to as embodiments). In addition, constituent elements in the following embodiments include those that can be easily assumed by those skilled in the art, those that are substantially the same, and those in a so-called equivalent range. Furthermore, the constituent elements disclosed in the following embodiments can be appropriately combined.

  The epoxy resin composition according to the present embodiment (hereinafter referred to as “the composition of the present embodiment”) includes an epoxy resin, a curing agent, a first curing accelerator, and a second curing accelerator. .

<Epoxy resin>
The epoxy resin contains a bisphenol A type epoxy resin and a urethane-modified epoxy resin. The epoxy resin can contain other epoxy resins in addition to the bisphenol A type epoxy resin and the urethane-modified epoxy resin. As an epoxy resin other than the bisphenol A type epoxy resin and the urethane-modified epoxy resin, any compound having two or more epoxy groups in the molecule can be used without any particular limitation. Examples of the epoxy resin include epoxy compounds having a bisphenyl group such as bisphenol F type, bisphenol S type, bisphenol AF type, and biphenyl type, polyalkylene glycol type, alkylene glycol type epoxy compounds, and epoxy compounds having a naphthalene ring. , Bifunctional glycidyl ether type epoxy resins such as epoxy compounds having a fluorene group; polyfunctional glycidyl ether type epoxies such as phenol novolac type, orthocresol novolac type, trishydroxyphenylmethane type, tetraphenylolethane type Resin; Glycidyl ester type epoxy resin of synthetic fatty acid such as dimer acid; N, N, N ′, N′-tetraglycidyldiaminodiphenylmethane (TGDDM), tetraglycidyl-m-xy Aromatic epoxy resins having a glycidylamino group such as range amine, triglycidyl-p-aminophenol, N, N-diglycidylaniline; epoxy compounds having a tricyclodecane ring (for example, dicyclopentadiene and m-cresol And epoxy compounds obtained by a production method in which epichlorohydrin is reacted after polymerizing such cresols or phenols. An epoxy resin can be used individually or in combination of 2 types or more, respectively.

  The epoxy resin is preferably selected from the group consisting of bisphenol A type epoxy resin, bisphenol F type epoxy resin, rubber-modified epoxy resin and urethane-modified epoxy resin. This is because it is easy to obtain a composition having a storage elastic modulus after curing of 1.0 GPa or less at −20 ° C. and 0.2 to 0.7 GPa at 80 ° C. Among these, it is more preferable that a bisphenol A type epoxy resin and a urethane-modified epoxy resin are included. By including the bisphenol A type epoxy resin and the urethane-modified epoxy resin, the composition of this embodiment can satisfy the performance as a structural adhesive.

(Bisphenol A type epoxy resin)
The bisphenol A type epoxy resin preferably has an epoxy equivalent in the range of 180 g / eq to 500 g / eq. In this embodiment, the bisphenol A type epoxy resin includes brominated bisphenol A type, hydrogenated bisphenol A type, and the like. A bisphenol A type epoxy resin can be used individually by 1 type or in combination of 2 or more types. Specific examples of the bisphenol A type epoxy resin include, for example, jER (registered trademark) series (827, 828, 834, etc.) manufactured by Japan Epoxy Resin, and Epicron (registered trademark) series (840, 850, etc.) manufactured by DIC. Adeka Resin (registered trademark) EP-4100 series manufactured by ADEKA, etc. can be appropriately selected and used. The content of the bisphenol A type epoxy resin is more than 10 parts by weight and 50 parts by weight or less, preferably 15 parts by weight or more and 45 parts by weight or less, more preferably 20 parts by weight or more and 40 parts by weight in 100 parts by weight of the epoxy resin. Or less. When the content of the bisphenol A type epoxy resin is within the above range, the composition of this embodiment can satisfy the performance as a structural adhesive.

(Bisphenol F type epoxy resin)
The bisphenol F-type epoxy resin preferably has an epoxy equivalent in the range of 150 g / eq to 500 g / eq. A bisphenol F type epoxy resin can be used individually by 1 type or in combination of 2 or more types. Specific examples of the bisphenol F type epoxy resin include, for example, jER (registered trademark) series (806, 807, etc.) manufactured by Japan Epoxy Resin, Epiklon (registered trademark) series (830, 835, etc.) manufactured by DIC, ADEKA, etc. It can be appropriately selected from Adeka Resin (registered trademark) EP-4900 series manufactured by the company.

(Urethane-modified epoxy resin)
The structure of the urethane-modified epoxy resin is not particularly limited as long as it is a resin having a urethane bond and two or more epoxy groups in the molecule. The urethane-modified epoxy resin preferably has an epoxy equivalent in the range of 200 g / eq to 250 g / eq. Urethane-modified epoxy resins can be used alone or in combination of two or more. Specific examples of the urethane-modified epoxy resin include, for example, Mitsui Chemicals Epokey (registered trademark) series (803, 802-30CX, 820-40CX, 834, etc.), ADEKA Adeka Resin (registered trademark) EPU series, It can be used by appropriately selecting from the EP series or the like. The content of the urethane-modified epoxy resin is 40 parts by mass or more and less than 90 parts by mass, preferably 50 parts by mass or more and 85 parts by mass or less, more preferably 60 parts by mass or more and 80 parts by mass in 100 parts by mass of the epoxy resin. It is as follows. When the content of the urethane-modified epoxy resin is within the above range, the composition of this embodiment can satisfy the performance as a structural adhesive.

(Rubber-modified epoxy resin)
The rubber-modified epoxy resin is not particularly limited as long as it is an epoxy resin having two or more epoxy groups in the molecule and having a skeleton made of rubber. Examples of the rubber forming the skeleton include polybutadiene, acrylonitrile butadiene rubber (NBR), butadiene-acrylonitrile rubber having carboxyl groups at both ends (carboxyl-terminated butadiene nitrile rubber (CTBN)), Butadiene-acrylonitrile rubber having amino groups at both ends (amino-terminated butadiene nitrile rubber (ATBN)), butadiene-acrylonitrile rubber having carboxyl groups and amino groups at both ends (carboxyl end and amino group) Base terminal polybutadiene-acrylonitrile rubber). One rubber-modified epoxy resin can be used alone, or two or more rubber-modified epoxy resins can be used in combination. Specifically, the rubber-modified epoxy resin can be appropriately selected from, for example, Adeka Resin (registered trademark) EPR series manufactured by ADEKA.

  The rubber-modified epoxy resin has a property that is easily compatible with the oil component. The composition which concerns on this embodiment can maintain stable adhesiveness with respect to the steel plate etc. which have an oil surface by including a rubber-modified epoxy resin.

  The epoxy resin used in producing the rubber-modified epoxy resin is not particularly limited as long as the epoxy equivalent is 200 g / eq or more, and conventionally known ones can be mentioned.

  The method for producing the rubber-modified epoxy resin is not particularly limited. For example, it can be produced by reacting rubber and epoxy in a large amount of epoxy. The epoxy (for example, epoxy resin) used when producing the rubber-modified epoxy resin is not particularly limited. For example, a conventionally well-known thing is mentioned.

  In the present embodiment, the epoxy equivalent of the rubber-modified epoxy resin and the amount of addition thereof indicate the amount as “rubber-modified epoxy resin containing the epoxy” since an excess of the epoxy resin used in the production is included.

<Curing agent>
The curing agent contains dicyandiamide (DICY) represented by the following formula (1). Dicyandiamide is a melt-crosslinked amine, and can be suitably used for a heat-curable one-component adhesive that melts and cures the crosslinked amine.

  The curing agent can include a curing agent other than dicyandiamide. Curing agents other than dicyandiamide are not particularly limited, and those usually used as curing agents for epoxy resins can be used. Examples of curing agents other than dicyandiamide include amines, acid anhydrides, novolak resins, phenols, mercaptans, Lewis acid amine complexes, onium salts, and imidazoles. Examples of amine-type curing agents include aromatic amines such as diaminodiphenylmethane and diaminodiphenylsulfone, aliphatic amines, imidazole derivatives, tetramethylguanidine, thiourea-added amines, and isomers and modified products thereof. Can do. Specifically, for example, 4,4-diaminodiphenylsulfone, imidazole derivatives such as 2-n-heptadecylimidazole, isophthalic acid dihydrazide, N, N-dialkylurea derivatives, N, N-dialkylthiourea derivatives, tetrahydro An acid anhydride such as phthalic anhydride, N-aminoethylpiperazine, melamine, guanamine, boron trifluoride complex compound, trisdimethylaminomethylphenol and the like can be used. In addition to dicyandiamide, one or more of these curing agents may be used in combination.

  The content of the curing agent is not particularly limited, and the optimum amount varies depending on the type of the curing agent. For example, the optimal amount for each curing agent known in the art can be preferably used. This optimum amount is described, for example, in Chapter 3 of “Review Epoxy Resin Basics” (Epoxy Resin Technical Association, published in 2003).

<First curing accelerator>
The first curing accelerator contains 3,4-dichlorophenyl-1,1-dimethylurea (DCMU) represented by the following formula (2). A 1st hardening accelerator is a condensation catalyst for hardening the composition of this embodiment. For example, the first curing accelerator has an effect of accelerating the curing reaction of dicyandiamide, so that the strength of the composition of the present embodiment can be improved.

  The first curing accelerator can contain other curing accelerators described later in addition to 3,4-dichlorophenyl-1,1-dimethylurea.

  The content of 3,4-dichlorophenyl-1,1-dimethylurea is 5 parts by mass or more and 15 parts by mass or less, preferably 5.5 parts by mass or more and 13 parts by mass or less with respect to 100 parts by mass of the epoxy resin. More preferably, it is 6 parts by mass or more and 12 parts by mass or less. If the content of 3,4-dichlorophenyl-1,1-dimethylurea is less than 5 parts by mass, the composition of this embodiment is not preferable because the peel strength is lowered. When the content of 3,4-dichlorophenyl-1,1-dimethylurea is more than 15 parts by mass, the cured product of the composition of the present embodiment is not preferable because it becomes brittle. When the content of 3,4-dichlorophenyl-1,1-dimethylurea is within the above range, the composition of the present embodiment can improve the peel strength.

<Second curing accelerator>
The second curing accelerator includes an imidazole compound (including an imidazole derivative) containing a triazine ring represented by the following formula (3). A 2nd hardening accelerator is a condensation catalyst for hardening the composition of this embodiment. The second curing accelerator can cure the composition of the present embodiment in a short time. In addition, in this embodiment, a short time means the time for 10 minutes or less.

  As the second curing accelerator, a cross-linked amine, an imidazole compound having a function as a promoter, and a derivative thereof are preferably used. The imidazole compound is a compound composed of an imidazole derivative having an unshared electron pair. The imidazole derivative functions as a cation receptor. In the present embodiment, the cation includes a proton. In this case, the imidazole derivative becomes an imidazole compound. Since the imidazole compound is hardly soluble in water and is insoluble in water, the imidazole compound contained in the epoxy resin is insoluble in water.

  Examples of the imidazole compound include compounds having a substituent in at least one of the 1-position, 2-position, 4-position and 5-position of imidazole as shown in the following general formula (4).

（上記一般式（４）において、Ｒ１、Ｒ２、Ｒ３およびＲ４は、水素基あるいは置換基を表す。それらは同一でも異なっていてもよい。但し、少なくとも１つは置換基であることが必要である。）

(In the above general formula (4), R1, R2, R3 and R4 represent a hydrogen group or a substituent. They may be the same or different, provided that at least one of them is a substituent. is there.)

  An imidazole compound containing a triazine ring is a compound obtained by modifying an imidazole compound with triazine. Examples of the compound obtained by modifying the imidazole compound with triazine include 2,4-diamino-6- [2′-methylimidazolyl- (1 ′)]-ethyl-s-triazine (2MZ-A), 2,4-diamino- 6- [2′-Ethyl-4′-methylimidazolyl- (1 ′)]-ethyl-s-triazine (2E4MZ-A), 2,4-diamino-6- [2′-undecylimidazolyl- (1 ′) )]-Ethyl-s-triazine (C11Z-A) and the like. Among these, 2,4-diamino-6- [2′-methylimidazolyl- (1 ′)]-ethyl-s-triazine (2MZ-A) can be cured in a short time. ) Can be suitably used. The imidazole compounds containing a triazine ring may be used alone or in combination of two or more.

  The imidazole compound containing a triazine ring may be an imidazole-isocyanuric acid adduct obtained by adding isocyanuric acid represented by the following formula (5) to an imidazole compound.

  The imidazole compound containing a triazine ring is solid at room temperature and is a water-insoluble particulate compound. The average particle size of the imidazole compound containing a triazine ring is preferably 5 μm or more and 50 μm or less. When the average particle diameter is within the above range, the composition of the present embodiment can be cured in a short time.

  A 2nd hardening accelerator can contain the other hardening accelerator mentioned later other than the imidazole compound containing a triazine ring mentioned above.

  The content of the imidazole compound containing a triazine ring is 1 part by mass or more and 10 parts by mass or less, preferably 2 parts by mass or more and 8 parts by mass or less, more preferably 2 parts by mass with respect to 100 parts by mass of the epoxy resin. The amount is 6 parts by mass or less. When the content of the imidazole compound containing a triazine ring is less than 1 part by mass, the composition of this embodiment is not preferable because it takes time to cure. When the content of the imidazole compound containing a triazine ring is more than 10 parts by mass, the composition of the present embodiment is not preferable because the storage stability is deteriorated. When the content of the imidazole compound containing a triazine ring is within the above range, the composition of the present embodiment can be cured in a shorter time. Moreover, by having a triazine ring, long-term storage stability and high heat resistance can be obtained.

[Coating material]
It is preferable that at least a part of the surface of the imidazole compound containing a triazine ring is coated with a coating material. By covering at least a part of the surface of the imidazole compound containing a triazine ring with a coating material, the composition of the present embodiment is further improved in long-term storage stability.

  The coating material is one or more selected from the group comprising an olefin polymer, polystyrene, polyester urethane, acrylic polymer, stearic acid, and isocyanate-containing acrylic polymer. In this embodiment, the mass of the imidazole compound containing the triazine ring coated with the coating material is an apparent mass including the mass of the coating material, and the mass of the imidazole compound alone is greater than the apparent mass of the coating material. This is the mass minus the mass.

(Olefin polymer)
The olefin polymer is not particularly limited as long as it does not have reactivity with the epoxy resin or has low reactivity, and a conventionally known olefin polymer can be used. Examples of the olefin polymer include α-olefin polymers.

  The α-olefin polymer is a crystalline higher α-olefin polymer obtained from a higher α-olefin having 10 or more carbon atoms from the viewpoint that it is solid at room temperature but melts sharply at a temperature near the melting point. Is preferred. Examples of the higher α-olefin having 10 or more carbon atoms include 1-decene, 1-undecene, 1-dodecene, 1-tridecene, 1-tetradecene, 1-pentadecene, 1-hexadecene, 1-heptadecene, 1-octadecene, Examples include 1-nonadecene and 1-eicosene.

  One preferred embodiment of the α-olefin polymer is a high hardness, low melting point α-olefin polymer in which the side chain has crystallinity from the viewpoints of storage properties and temperature-sensitive melting properties. . The α-olefin polymer is not particularly limited for its production. For example, a method of polymerizing a higher α-olefin having 10 or more carbon atoms while controlling stereoregularity of the main chain with a metallocene catalyst or the like can be mentioned. By such a method, an α-olefin polymer having side chain crystallinity can be produced.

  The α-olefin polymer preferably has a melting point of 50 ° C. or higher and 110 ° C. or lower from the viewpoint of being suitable as a coating material. As the α-olefin polymer having such a melting point, for example, a raw material monomer obtained by mixing each α-olefin having 20, 22 and 24 carbon atoms in a ratio of 35 to 45:30 to 40:15 to 25 is used. An α-olefin polymer and an α-olefin polymer having a raw material monomer obtained by mixing each α-olefin having 26 and 28 carbon atoms in a ratio of 30:70 to 40:60 can be mentioned. Examples of the former α-olefin polymer include an eicosene / docosene / tetracocene copolymer (melting point: about 60 ° C., ratio of carbon numbers 20, 22 and 24: 43:36:21), and the latter α-olefin polymer. Examples of the combination include a hexacocene / octacocene copolymer (melting point: about 75 ° C., ratio of 26 and 28 carbon atoms: 38:62). Among these, the latter α-olefin polymer is more preferably used from the viewpoint of being able to contribute to improvement in storage stability due to good coating.

  The olefin polymer may be produced by a known method, or a commercially available product may be used. As a commercially available product, for example, ELCRYSTA 7100 manufactured by Idemitsu Kosan Co., Ltd. is preferably used.

(polystyrene)
Polystyrene is not particularly limited, and conventionally known polystyrene can be used.

(Polyester urethane)
Polyester urethane is obtained by reaction of a polyisocyanate compound and a polyester polyol.

Specific examples of the polyisocyanate compound include TDI (for example, 2,4-tolylene diisocyanate (2,4-TDI), 2,6-tolylene diisocyanate (2,6-TDI)), MDI ( For example, 4,4′-diphenylmethane diisocyanate (4,4′-MDI), 2,4′-diphenylmethane diisocyanate (2,4′-MDI)), 1,4-phenylene diisocyanate, polymethylene polyphenylene polyisocyanate, xylylene diene Aromatic polyisocyanates such as isocyanate (XDI), tetramethylxylylene diisocyanate (TMXDI), tolidine diisocyanate (TODI), 1,5-naphthalene diisocyanate (NDI), triphenylmethane triisocyanate; hexamethylene diisocyanate Aliphatic polyisocyanates such as anate (HDI), trimethylhexamethylene diisocyanate (TMHDI), lysine diisocyanate, norbornane diisocyanate (NBDI); transcyclohexane-1,4-diisocyanate, isophorone diisocyanate (IPDI), bis (isocyanatomethyl) cyclohexane (H ₆ XDI), cycloaliphatic polyisocyanates such as dicyclohexylmethane diisocyanate (H ₁₂ MDI); carbodiimide-modified polyisocyanates; isocyanurate-modified polyisocyanates; and the like.

  As the polyester polyol, known polyol compounds used for the production of polyesters can be used without particular limitation. Specifically, for example, ethylene glycol, propylene glycol, butanediol, pentanediol, hexanediol, neopentyl glycol. At least one selected from the group consisting of glycerin, 1,1,1-trimethylolpropane, 1,4-cyclohexanedimethylol, 2,2-bishydroxymethyl-n-butyric acid and other low molecular polyols, At least one selected from the group consisting of glutaric acid, adipic acid, pimelic acid, suberic acid, sebacic acid, dimer acid, terephthalic acid, isophthalic acid, metaphthalic acid, naphthalenedicarboxylic acid and other aliphatic carboxylic acids and oligomeric acids Condensation polymers of; and the like can be used; propiolactone, ring-opening polymers such as valerolactone.

  As a combination of the polyisocyanate compound and the polyester polyol in producing the polyester urethane, diphenylmethane diisocyanate (MDI) or isophorone diisocyanate (IPDI) and 1,4-cyclohexanedimethylol, opentyl glycol or 1,6-hexanediol The combination with is suitably exemplified.

  The manufacturing method of polyester urethane is not specifically limited, For example, it can manufacture by heating and stirring a polyisocyanate compound and polyester polyol at 50 to 130 degreeC. Moreover, if necessary, for example, a urethanization catalyst such as an organic tin compound, organic bismuth, or amine can be used.

  A commercially available product can be used as the polyester urethane. As a commercially available polyester urethane, for example, Byron series manufactured by Toyobo Co., Ltd. can be used.

(Acrylic polymer)
The acrylic polymer is not particularly limited as long as it is a polymer having an acrylic skeleton. For example, a monomer unit containing an ester group such as alkyl acrylate or alkyl methacrylate; carboxyl such as acrylic acid or methacrylic acid; Monomer unit containing a group; Monomer unit containing an amide group such as acrylamide, methacrylamide, N-methylol acrylamide, N-methylol methacrylamide; Monomer containing an epoxy group such as glycidyl acrylate or glycidyl methacrylate Body unit; monomer unit containing amino group such as diethylaminoethyl acrylate, diethylaminoethyl methacrylate, aminoethyl vinyl ether; polymer or copolymer such as polyoxyethylene acrylate and polyoxyethylene methacrylate And the like. The acrylic polymer may contain monomer units derived from acrylonitrile, styrene, α-methylstyrene, alkyl vinyl ether, vinyl chloride, vinyl acetate, vinyl propionate, ethylene, etc. in addition to the above monomer units. Good. Among these, an acrylic polymer containing a carboxyl group is preferable.

  The acrylic polymer may be produced by a known method, or a commercially available product may be used. As a commercially available product, for example, ARUFON (registered trademark) UC-3000 series manufactured by Toagosei Co., Ltd. is preferably used.

(stearic acid)
Stearic acid is a saturated fatty acid. Stearic acid is not particularly limited, and conventionally known ones can be used.

(Isocyanate-containing acrylic polymer)
The isocyanate-containing acrylic polymer is not particularly limited as long as it is an acrylic polymer having an isocyanate group. For example, an isocyanate-containing acrylic polymer can be obtained by reacting an isocyanate group-containing compound with an acrylic ester. Specifically, for example, methyl methacrylate and 2-isocyanatoethyl methacrylate (trade name: Karenz MOI, manufactured by Showa Denko KK) are added to ethyl acetate, and azobisisobutyronitrile (AIBN) is added to about 50 ° C. Is reacted for about 5 hours to obtain an isocyanate-containing acrylic polymer.

  The olefin polymer, polystyrene, polyester urethane, acrylic polymer, stearic acid and isocyanate-containing acrylic polymer preferably have a melting point of 50 ° C. or higher and 110 ° C. or lower from the viewpoint of being suitable as a coating material, and 55 ° C. or higher and 105 ° C. or lower. Are more preferable, and those having a temperature of 60 ° C. or higher and 100 ° C. or lower are more preferable. This is because when the melting point of the coating material component is lower than 50 ° C when mixed with the epoxy resin, the coating material dissolves and is embedded during storage at room temperature to 40 ° C (imidazole compound) It penetrates into the epoxy resin, and as a result, the storage stability is lowered. In addition, when the melting point of the coating material component is higher than 110 ° C., the coating material does not completely melt when heated at a low temperature, so that a part of the surface of the imidazole compound remains covered, and the activity of the imidazole compound decreases. It is because it will do. Therefore, when the melting point of the coating material component is within the above range, the composition of the present embodiment can improve long-term storage stability. In the present embodiment, the curing at a low temperature refers to a temperature of 130 ° C. or lower.

  Among the coating materials, olefin polymers and stearic acid are preferable from the viewpoint that the active groups on the surface of the imidazole compound can be covered and the activity of the imidazole compound can be stably reduced before the heat curing. Can be used.

  The method for producing the second curing accelerator coated with the coating material is not particularly limited, and for example, it can be produced by a known method. For example, after the coating material is dissolved in an organic solvent, the imidazole compound is added and stirred using a stirrer, etc., and then the solid material is removed by filtration, and the solid material is coated with a coating material by grinding with a ball mill. And a method of producing a second curing accelerator.

  By coating the imidazole compound containing the triazine ring contained in the curing accelerator with a coating material, the composition of the present embodiment can further improve long-term storage stability.

  The composition of this embodiment can contain other hardening accelerators other than a 1st hardening accelerator and a 2nd hardening accelerator in a 1st hardening accelerator and a 2nd hardening accelerator. The other curing accelerators other than the first curing accelerator and the second curing accelerator are not particularly limited as long as they have an effect of promoting the curing reaction of dicyandiamide, and conventionally known curing accelerators may be used. it can. Specifically, for example, 1,1 ′-(4-methyl-1,3-phenylene) bis (3,3-dimethylurea), phenyl-dimethylurea, methylene-diphenyl-bisdimethylurea, 3-phenyl- 1,1-dimethylurea, urea derivatives such as 3- (3-chloro-4-methylphenyl) -1,1-dimethylurea, tertiary amines, imidazole compounds, urea compounds such as phenyldimethylurea (PDMU), three Examples thereof include amine complexes such as fluorinated monoethylamine and an amine trichloride complex.

  The composition according to this embodiment includes additives in addition to the above-described epoxy resin, curing agent, first curing accelerator, and second curing accelerator as long as the object of the present invention is not impaired as necessary. be able to. Examples of additives include plasticizers, fillers, adhesion promoters, reactive diluents, curing catalysts, thixotropic agents, silane coupling agents, pigments, dyes, anti-aging agents, antioxidants, and antistatic agents. , Flame retardant, drying oil, adhesion-imparting agent, dispersant, dehydrating agent, ultraviolet absorber, solvent and the like. Two or more of these may be contained.

  The manufacturing method of the composition which concerns on this embodiment is not specifically limited, For example, it can manufacture by a conventionally well-known method. For example, an epoxy resin, a curing agent, a first curing accelerator, a second curing accelerator, a filler, an adhesion-imparting agent, and an additive as necessary are blended under reduced pressure or an inert gas atmosphere such as nitrogen. And kneading using a stirring device such as a roll, a kneader, an extruder, a universal stirrer, and a mixing mixer, and mixing by uniformly dispersing.

  The composition of this embodiment is stored in a closed container, and a cured product can be obtained by heating to a predetermined temperature during use. The temperature to be heated when the composition of the present embodiment is cured is preferably 60 ° C or higher and 130 ° C or lower, more preferably 65 ° C or higher and 125 ° C or lower, and further preferably 70 ° C or higher and 120 ° C or lower. . If the heating temperature is within the above range, the composition of this embodiment can be sufficiently cured. The heating time is preferably 10 minutes or less, more preferably 2 minutes or more and 8 minutes or less, and further preferably 4 minutes or more and 6 minutes or less. If the heating time is within the above range, the composition of the present embodiment can be sufficiently cured.

  Thus, the composition according to the present embodiment includes an epoxy resin containing a bisphenol A type epoxy resin and a urethane-modified epoxy resin, a curing agent containing dicyandiamide, and 3,4-dichlorophenyl-1,1-dimethylurea. A predetermined amount of each of the first curing accelerator and the second curing accelerator including an imidazole compound containing a triazine ring is included. By containing a predetermined amount of 3,4-dichlorophenyl-1,1-dimethylurea as described above and a predetermined amount of the imidazole compound as described above, the cured product of the composition of the present embodiment is curable at low temperature. And excellent storage stability.

  The composition according to this embodiment is preferably used as a structural adhesive because the composition according to this embodiment can be cured at a low temperature in a short time while maintaining high adhesive strength and is excellent in storage stability. be able to. Here, the “structural adhesive” is a highly reliable adhesive (JIS K6800) with little deterioration in adhesive properties even when a large load is applied for a long time. For example, it can be used as an adhesive for structural members in the fields of automobiles, vehicles (bullet trains, trains), civil engineering, architecture, electronics, aircraft, and the space industry. The composition according to this embodiment can be suitably used as an adhesive for automobile structures such as automobiles and vehicles (bullet trains, trains) and an adhesive for vehicle structures.

  In addition to the structural adhesive, the composition according to this embodiment can also be used as an adhesive for general office work, medical use, carbon fiber, electronic material, and the like. As adhesives for electronic materials, interlayer adhesives for multilayer substrates such as build-up substrates, optical component bonding adhesives, optical disk bonding adhesives, printed wiring board mounting adhesives, die bonding adhesives, underfills And adhesives for semiconductors such as BGA reinforcing underfill, anisotropic conductive film (ACF), and anisotropic conductive paste (ACP).

  Moreover, the composition according to the present embodiment can be used as an adhesive, as well as an article for general use in which a thermosetting resin such as an epoxy resin is used. For example, paints, coating agents, molding materials (including sheets, films, FRP, etc.), insulating materials (including printed circuit boards, electric wire coatings, etc.), sealants, flat panel display sealing agents, fiber binding agents, etc. Can be mentioned.

  Hereinafter, the present invention will be specifically described with reference to examples. However, the present invention is not limited to these.

<Preparation of one-component heat-curable epoxy resin composition>
Each component shown in Tables 1 and 2 was blended in the addition amount (parts by mass) shown in the same table, and these were uniformly mixed to prepare each epoxy resin composition shown in Tables 1 and 2. Tables 1 and 2 show the addition amount (parts by mass) of each component in each Example and Comparative Example. In addition, the addition amount (mass part) of the imidazole compound containing the triazine ring coat | covered with the coating | covering material in Tables 1 and 2 is an addition amount (mass part) including the mass of a coating | covering material, and content of an imidazole compound As, it can obtain | require from the mixing ratio of the coating | covering material and imidazole compound which are shown in the preparation methods of the 2nd hardening accelerators 5-10 mentioned later. For example, in the case of the second curing accelerator 5 (olefin polymer coating), since the mixing ratio of the olefin polymer and the imidazole compound is 4: 1, the imidazole compound containing the triazine ring coated with the coating material is used. For example, if the addition amount (parts by mass) is 10 parts by mass, the addition amount (parts by mass) of the imidazole compound is 2 parts by mass. The same applies to the addition amount (parts by mass) of an imidazole compound containing a triazine ring coated with another coating material.

  In addition, the preparation methods of the 2nd hardening accelerator 5-10 coat | covered with the coating | covering material are shown.

(Preparation of second curing accelerator 5 (olefin polymer coating))
An olefin polymer (trade name: Elkrista 7100, manufactured by Idemitsu Kosan Co., Ltd.) was dissolved in toluene at 70 ° C. Thereafter, an imidazole compound (trade name: 2MZ-A, manufactured by Shikoku Kasei Kogyo Co., Ltd.) was added and stirred at room temperature, and then a solid was taken out by filtration. The solid matter taken out was pulverized by a ball mill to obtain a particle-shaped (diameter: about 5 to 10 μm) olefin polymer-coated curing accelerator. The mixing ratio of the olefin polymer and the imidazole compound was 4: 1.

(Preparation of second curing accelerator 6 (acrylic polymer coating))
Acrylic polymer (trade name: ARUFON UC-3000, manufactured by Toagosei Co., Ltd.) was dissolved in methyl ethyl ketone (MEK). Thereafter, an imidazole compound (trade name: 2MZ-A, manufactured by Shikoku Kasei Kogyo Co., Ltd.) was added and stirred at room temperature, and then a solid was taken out by filtration. The solid matter taken out was pulverized by a ball mill to obtain a particle-shaped (about 5 to 10 μm diameter) acrylic polymer-coated curing accelerator. The mixing ratio of the acrylic polymer and the imidazole compound was 0.5: 1.

(Preparation of second curing accelerator 7 (polystyrene coating))
Polyester (trade name: Dick Elastylene, manufactured by DIC Corporation) was dissolved in methyl ethyl ketone. Thereafter, an imidazole compound (trade name: 2MZ-A, manufactured by Shikoku Kasei Kogyo Co., Ltd.) was added and stirred at room temperature, and then a solid was taken out by filtration. The solid matter taken out was pulverized by a ball mill to obtain a particle-like (average particle size of about 20 to 30 μm) polystyrene-coated curing accelerator. The mixing ratio of polystyrene and imidazole compound was 0.5: 1.

(Preparation of second curing accelerator 8 (polyester urethane coating))
Polyurethane (trade name: Byron UR1700, manufactured by Toyobo Co., Ltd.) was dissolved in methyl ethyl ketone. Thereafter, an imidazole compound (trade name: 2MZ-A, manufactured by Shikoku Kasei Kogyo Co., Ltd.) was added and stirred at room temperature, and then a solid was taken out by filtration. The solid matter taken out was pulverized with a ball mill to obtain a curing accelerator for polyester urethane coating in the form of particles (average particle size of about 20 to 30 μm). The mixing ratio of the polyester urethane and the imidazole compound was 1: 1.

(Preparation of second curing accelerator 9 (stearic acid coating))
Stearic acid was dissolved in methyl ethyl ketone. Thereafter, an imidazole compound (trade name: 2MZ-A, manufactured by Shikoku Kasei Kogyo Co., Ltd.) was added and stirred at room temperature for 24 hours, and then a solid was taken out by filtration. The solid matter taken out was pulverized with a ball mill to obtain a curing accelerator for stearic acid coating in a particulate form (average particle diameter of about 20 to 30 μm). The mixing ratio of stearic acid and imidazole compound was 1: 1.

(Preparation of second curing accelerator 10 (isocyanate-containing acrylic polymer coating))
Add 20 g of methyl methacrylate and 0.25 g of 2-isocyanate methyl methacrylate (trade name: Karenz MOI, Showa Denko) to ethyl acetate, add azobisisobutyronitrile (AIBN), and react at 50 ° C. for 5 hours. Thus, an isocyanate-containing acrylic polymer was obtained. Next, an imidazole compound (trade name: 2MZ-A, manufactured by Shikoku Kasei Kogyo Co., Ltd.) and the isocyanate-containing acrylic polymer obtained above were added to methyl ethyl ketone and stirred, and then a solid was taken out by filtration. The solid matter taken out was pulverized with a ball mill to obtain a curing accelerator for coating an isocyanate-containing acrylic polymer in a particulate form (average particle size of about 20 to 30 μm). The mixing ratio of the isocyanate-containing acrylic polymer and the imidazole compound was 1: 1.

<Evaluation>
Peel strength and storage stability were evaluated using the epoxy resin compositions of Examples and Comparative Examples shown in Tables 1 and 2.

[Peel strength]
(Preparation of T-shaped test piece for peeling)
A plurality of T-shaped stripping test pieces (simply referred to as test pieces) were prepared using the epoxy resin compositions of Examples and Comparative Examples shown in Tables 1 and 2. FIG. 1 is a perspective view of a test piece. As shown in FIG. 1, the adhesion surface (120 mm from one end) of two steel plates (length 25 mm × width 150 mm × thickness 0.8 mm) was degreased. A plurality of spacers for setting the thickness of the epoxy resin composition to about 0.15 mm were provided on the degreased adhesive surface. Next, the epoxy resin compositions of the respective examples and comparative examples were respectively applied to the adhesion surfaces of the respective test pieces, bonded as shown in FIG. 1, and bonded by crimping with iron clips to prepare test pieces. . Furthermore, after wiping off the epoxy resin composition protruding from the test piece, it was placed in a heating furnace, and the furnace atmosphere was set to 130 ° C. for 5 minutes to cure. The test piece taken out from the heating furnace was cooled to room temperature, and then the unbonded portions were bent outward by about 90 degrees, respectively, and then the iron clip was removed to prepare a test piece as shown in FIG.

  The peel strength is measured by aligning the long axis of the test piece with the center line of the tensile tester, and the portions X and Y where both ends of the test piece are 20 mm so that the load passes correctly on the line (see FIG. 1). The sample was sufficiently fixed with a specimen holder of a tensile tester. Next, a tensile test was performed under the condition of a tensile speed of 200 mm / min. When the peel strength was 110 N / 25 mm or more, it was evaluated that the adhesiveness was excellent. The results are shown in Tables 1 and 2.

[Storage stability]
The epoxy resin composition of each Example and each Comparative Example was left in an oven adjusted to 40 ° C. and 10% RH or less, and the number of days until each epoxy resin composition was cured was measured. If the number of days was 20 days or more, it was evaluated that the storage stability was excellent. The results are shown in Tables 1 and 2.

The components shown in Tables 1 and 2 are as follows.
・ Epoxy resin 1: BisA type epoxy resin, trade name: “EP4100E”, epoxy equivalent: 188, manufactured by ADEKA ・ Epoxy resin 2: urethane modified epoxy resin, trade name: “EP78-11”, manufactured by ADEKA ・ Curing agent : Dicyandiamide, trade name: “DICY15”, manufactured by Japan Epoxy Resin Co., Ltd. • First curing accelerator: 3,4-dichlorophenyl-1,1-dimethylurea (“DCMU-99”, manufactured by Hodogaya Chemical Co., Ltd.)
Second curing accelerator 1: 2,4-diamino-6- [2′-methylimidazolyl- (1 ′)]-ethyl-s-triazine, trade name “2MZ-A”, manufactured by Shikoku Kasei Kogyo Co., Ltd. 2. Curing accelerator 2: 2,4-diamino-6- [2′-ethyl-4′-methylimidazolyl- (1 ′)]-ethyl-s-triazine, trade name “2E4MZ-A”, Shikoku Kasei Kogyo Co., Ltd. -Second curing accelerator 3: 2,4-diamino-6- [2'-undecylimidazolyl- (1 ')]-ethyl-s-triazine, trade name "C11Z-A", manufactured by Shikoku Kasei Kogyo Co., Ltd. Second curing accelerator 4: 2 methylimidazole, trade name “2MZ-H”, manufactured by Shikoku Kasei Kogyo Co., Ltd. Second curing accelerator 5: Second curing accelerator for the olefin polymer coating obtained above 2 curing accelerator 6: second curing acceleration of the acrylic polymer coating obtained above Agent-Second curing accelerator 7: Second curing accelerator of the polystyrene coating obtained above-Second curing accelerator 8: Second curing accelerator of the polyester urethane coating obtained above-Second curing accelerator 9: Second curing accelerator for stearic acid coating obtained above-Second curing accelerator 10: Second curing accelerator for isocyanate-containing acrylic polymer coating obtained above-Filler: Carbon black, trade name " MA600 ”, manufactured by Mitsubishi Chemical Corporation ・ Adhesion imparting agent: epoxy silane, trade name“ KBM-403 ”, manufactured by Shin-Etsu Chemical Co., Ltd.

  From Tables 1 and 2, it was confirmed that in each of Examples 1 to 15, the cured product of the epoxy resin composition had a peel strength of 110 N / 25 mm or more. Moreover, in Examples 1-15, it was confirmed that the epoxy resin composition has a storage stability of 20 days or more.

  On the other hand, as for Comparative Examples 1-9, it was confirmed that all the hardened | cured materials of an epoxy resin composition have peeling strength of 100 N / 25mm or less, or are uncured. In Comparative Examples 1 to 5 and 8, the epoxy resin compositions had a storage stability of 20 days or longer, but Comparative Examples 6, 7, and 9 were confirmed to be 10 days or shorter.

  Therefore, it was found that the cured product of the epoxy resin composition of the present invention is excellent in curability at low temperature and storage stability. Therefore, since the cured product of the epoxy resin composition of the present invention has stable and excellent adhesiveness even when cured at a low temperature in a short time, it is suitable as a highly reliable adhesive, particularly a structural adhesive. Can be used.

Claims (5)

An epoxy resin including a bisphenol A type epoxy resin and a urethane-modified epoxy resin;
A curing agent comprising dicyandiamide;
A first curing accelerator comprising 3,4-dichlorophenyl-1,1-dimethylurea;
A second curing accelerator comprising an imidazole compound containing a triazine ring;
Including
The content of the 3,4-dichlorophenyl-1,1-dimethylurea is 5 parts by mass or more and 15 parts by mass or less with respect to 100 parts by mass of the epoxy resin,
Content of the said imidazole compound is 1 mass part or more and 10 mass parts or less with respect to 100 mass parts of said epoxy resins, The 1 liquid heat-curing type epoxy resin composition characterized by the above-mentioned.   The imidazole compound is 2,4-diamino-6- [2′-methylimidazolyl- (1 ′)]-ethyl-s-triazine, 2,4-diamino-6- [2′-ethyl-4′-methyl. One selected from the group comprising imidazolyl- (1 ′)]-ethyl-s-triazine and 2,4-diamino-6- [2′-undecylimidazolyl- (1 ′)]-ethyl-s-triazine, or The one-component heat-curable epoxy resin composition according to claim 1, which is more than that.   The one-component heat-curable epoxy resin composition according to claim 1 or 2, wherein at least part of the surface of the imidazole compound is coated with a coating material.   The said coating | covering material is 1 type or more chosen from the group containing an olefin polymer, a polystyrene, a polyester urethane, an acrylic polymer, a stearic acid, and an isocyanate containing acrylic polymer, It is any one of Claim 1 to 3 One-component heat-curable epoxy resin composition.   The one-component heat-curable epoxy resin composition according to claim 3 or 4, wherein the coating material has a melting point of 50 ° C or higher and 110 ° C or lower.

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