JPH0464614B2 - - Google Patents

Description

[Detailed description of the invention]

(Field of Industrial Application) The present invention relates to a thermosetting resin composition, and more particularly to a thermosetting resin composition whose cured product has excellent impact resistance and crack resistance, and also has a high heat distortion temperature. (Prior art) Epoxy resins have the advantages of being available in various grades from liquid to solid at room temperature, being able to be cured under either room temperature or heating conditions by selecting a hardening agent, and not producing by-products during curing. In addition, the cured product must have excellent mechanical strength and adhesive strength, exhibit excellent electrical properties, and have good chemical properties such as chemical resistance and moisture resistance. Because of its excellent performance, it is widely used in paints, electrical insulation materials, civil engineering and construction materials, adhesives, etc. However, depending on the conditions of use, epoxy resins may cause cracks in the cured product, and the following various methods have been proposed to improve crack resistance. (1) Lower the concentration of epoxy groups contained in epoxy resin and reduce the crosslink density. (2) Introducing long-chain aliphatic substituents to impart flexibility to the resin. (3) Use a long-chain curing agent such as aliphatic polyamide, polyacid polyanhydride, or long-chain polymercaptan. (4) Use monofunctional epoxy together to achieve so-called intramolecular plasticization. (5) Mix non-reactive plasticizing components such as polyoxyalkylene polyether, phthalate ester, and polycaprolactone. However, all of these methods have the drawback of significantly lowering the heat distortion temperature, which is one measure of the heat resistance of the cured product. On the other hand, it is also widely used to reduce the coefficient of thermal expansion of the system and improve crack resistance by incorporating a large amount of an inorganic filler whose coefficient of thermal expansion is lower than that of the resin component. However, although this method is useful in that it does not lower the heat distortion temperature of the resin component, it does not improve the crack resistance of the resin component itself, and the viscosity of the system increases, resulting in poor workability. There are disadvantages that are not desirable. Therefore, there is a strong desire to develop a resin composition that provides a cured product with excellent crack resistance and a high heat distortion temperature. (Problems to be Solved by the Invention) An object of the present invention is to eliminate the drawbacks of the prior art, and to create a thermosetting resin composition whose cured product has excellent impact resistance and crack resistance, as well as excellent heat resistance. It's about providing things. (Means for Solving the Problems) The present invention provides an epoxy resin (A) having two or more epoxy groups in the molecule, an acid anhydride (B), a carboxyl group in the molecule, an ester bond, and a radically polymerizable resin. The present invention relates to a thermosetting resin composition containing a polymerizable monomer (C) having a double bond and a radical polymerization initiator (D). Examples of the epoxy resin (A) having two or more epoxy groups in the molecule used in the present invention include bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol AD type epoxy resin, polyhydric alcohol polyglycidyl ether of polybasic acid, polyglycidyl ester of polybasic acid, 3,4
- Alicyclic epoxy resins such as epoxycyclohexylmethyl (3,4-epoxycyclohexane) carboxylate and vinylcyclohexene diepoxide, phenol novolac type epoxy resins,
Examples include cresol novolak type epoxy resins and epoxy resins having a hydantoin ring. Examples of the acid anhydride (B) used as a curing agent for curing the epoxy resin (A) in the present invention include phthalic anhydride, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, hexahydrophthalic anhydride, Examples include methylhexahydrophthalic anhydride, maleic anhydride, dodecenylsuccinic anhydride, and trimellitic anhydride. A carboxyl group in the molecule used in the present invention,
Examples of the polymerizable monomer having an ester bond and an acryloyl or methacryloyl radically polymerizable double bond include 2-(meth)acryloyloxyethylphthalic acid, 2-(meth)
Acryloyloxyethyltetrahydrophthalic acid, 2-(meth)acryloyloxyethylhexahydrophthalic acid, 2-(meth)acryloyloxyethylmethylhexahydrophthalic acid, 2-
(meth)acryloyloxyethylsuccinic acid, 2
-(meth)acryloyloxyethylmaleic acid,
Examples include 2-(meth)acryloyloxypropyl phthalic acid and 2-(meth)acryloyloxypropylmaleic acid. These are polymerizable monomers with low volatility, low viscosity, and good radical polymerizability. Examples of the radical polymerization initiator (D) used for polymerizing the polymerizable monomer (C) in the present invention include t-butyl perbenzoate, t-butyl peroctoate, cumene hydroperoxide, benzoyl Examples include organic peroxides such as peroxide, azobisisobutyronitrile, and the like. The thermosetting resin composition of the present invention can be obtained by blending the epoxy resin (A), the acid anhydride (B), the polymerizable monomer (C), and the radical polymerization initiator (D). It will be done. In this case, the blending amount of the acid anhydride (B) is preferably 0.3 to 1.4 equivalents per equivalent of the epoxy resin (A) from the viewpoint of not lowering the heat distortion temperature. In addition, the blending amount of the polymerizable monomer (C) is 0.1 to 1.6 in terms of carboxyl group per equivalent of the epoxy resin (A) in terms of crack resistance, shrinkage during curing, and heat distortion temperature. Equivalent amounts are preferred. In addition, the amount of the radical polymerization initiator (D) is determined based on the polymerizable monomer (C), taking into account the polymerization rate and molecular weight.
It is preferably 0.1 to 5 parts by weight per 100 parts by weight. In addition to the components (A) to (D), the thermosetting resin composition of the present invention contains, for example, an epoxy resin diluent such as butyl glycidyl ether, phenyl glycidyl ether, an imidazole compound, tertiary amines, quaternary It may contain reaction catalysts such as ammonium salts, fillers such as silica, aluminum hydroxide, and calcium carbonate, flame retardants such as halogen compounds, antimony trioxide, and red phosphorus, coupling agents, and colorants. Furthermore, the thermosetting resin composition of the present invention contains a polymerizable monomer copolymerizable with the polymerizable monomer (C), such as methyl (meth)acrylate, butyl (meth)acrylate, ethylene glycol di( It may contain meth)acrylate, hexanediol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, etc. as necessary. (Effects of the Invention) The cured product obtained from the thermosetting resin composition of the present invention has excellent impact resistance, crack resistance, and heat distortion temperature, which is one of the measures of heat resistance. In addition, the polymerizable monomer (C) is combined with an epoxy resin (A) and an acid anhydride.
By using it in combination with (B), the crack generation temperature can be lowered by about 20 to 50% compared to conventional resin compositions.
℃ can be improved. The thermosetting resin composition of the present invention can be used in a wide range of fields such as paints, electrical insulation materials, civil engineering and construction materials, and adhesives. (Example) "Parts" in the following examples mean parts by weight. Examples 1 to 6 Each composition was prepared by blending the compounds shown in Table 1 in the proportions (parts) shown in the table. Each of these compositions was cast into a mold of a predetermined shape, heated at 80°C for 5 hours, and then heated at 120°C for 5 hours.
C. for 5 hours to obtain a cured product. Using these cured products, the following properties were measured: thermal deformation temperature, bending strength, bending modulus, Izot impact strength, and crack initiation temperature (crack resistance). The results are shown in Table 1. The evaluation method for each characteristic is as follows. (1) Heat distortion temperature: A test piece of 120 x 12.5 x 5 mm was prepared and measured in accordance with ASTM D648. (2) Bending strength and bending modulus: 120×12.5×5
It was measured according to JIS K6911 using a mm test piece. (3) Izot impact strength: Measured using a 45 x 12.5 x 5 mm unnotched test piece, and calculated by dividing the obtained value by the cross-sectional area of the test piece. (4) Crack occurrence temperature (Tables 1 to 3): A 1/2 inch stainless steel spring washer was set in a metal shear plate with a diameter of 60 mm, and 30 g of the composition was injected and cured to prepare a test piece. After curing, remove the shear coat and leave it at 23℃ for 72 hours, then 100/1hr.
A heat cycle test was conducted for 3 cycles at -20°C/1 hr, and the occurrence of cracks was observed.
For the samples in which no cracks occurred, a similar test was conducted with the low temperature lowered by 10°C, and the temperature was subsequently lowered successively to determine the temperature (°C) at which cracks occurred. Note that two test pieces were used for each test piece, and the average value was expressed. (5) Cracking resistance (Table 4): A 7/8-inch stainless steel spring washer was used, the injection amount of the composition was 50 to 60 g, and the other conditions were the same as in the case of measuring the crack occurrence temperature in (4). In the same manner, the crack occurrence temperature (°C) was determined, and this was determined as the crack resistance.

【table】

[Table] Examples 7 to 11 Each composition was prepared by blending the compounds shown in Table 2 in the proportions (parts) shown in the table; using each composition, the same procedure as in Examples 1 to 6 was carried out. Each characteristic was measured and evaluated. The results are shown in Table 2.

[Table] Comparative Examples 1 to 6 Each composition was prepared by blending the compounds shown in Table 3 in the proportions (parts) shown in the table, and the compositions were used in the same manner as Examples 1 to 6. Each characteristic was measured and evaluated. The results are shown in Table 3.

【table】

[Table] Examples 12 to 13 and Comparative Examples 7 to 8 Each composition was prepared by blending the compounds shown in Table 4 in the proportions (parts) shown in the table, and each composition was used to prepare Example 1. - Each characteristic was measured and evaluated in the same manner as in 6. The results are shown in Table 4.

[Table] From the results in Tables 1 to 3, the cured product of the resin composition of the present invention has excellent impact resistance and crack resistance,
Furthermore, it is shown that heat resistance is not impaired. Furthermore, from the results in Table 4, in the resin composition of the present invention, the polymerizable monomer (C) having a carboxyl group, an ester bond, and a radically polymerizable double bond in the molecule is combined with the epoxy resin (A) and It is shown that the use of the composition in combination with the acid anhydride (B) significantly improves the cracking temperature of the cured product compared to the composition of the comparative example.

Claims (1)

[Claims] 1 Epoxy resin (A) having two or more epoxy groups in the molecule, acid anhydride (B), polymerization having a carboxyl group, ester bond, and acryloyl or methacryloyl radically polymerizable double bond in the molecule 1. A thermosetting resin composition comprising a monomer (C) and a radical polymerization initiator (D).