JPS648649B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a new and useful prepreg, and more particularly to a prepreg that contains a specific curable resin and a fibrous reinforcing material as essential components and has particularly excellent workability and compression moldability. In general, epoxy prepregs made of epoxy resin and fibrous reinforcing materials such as glass fibers and carbon fibers have excellent heat resistance, chemical resistance, water resistance, adhesion, electrical properties, and mechanical properties of epoxy resins, and also harden. Because of its low shrinkage and the fact that prepreg itself is easy to handle as a molding material, it is used as a structural material for printed circuit boards, aviation, space, and vehicles. Among these, epoxy prepreg for printed circuit boards uses glass fiber as the base material.
On the other hand, epoxy resins containing solvents are mainly used as resins, but solvent-free resins are desired in order to improve economic efficiency and reduce pollution. Furthermore, in the case of epoxy prepreg for structural materials, there is a demand for epoxy resins that can be easily impregnated into glass fibers, carbon fibers, etc., and that can be used as FRP matrices to shorten molding time. By the way, as a solvent-free epoxy resin matrix, polyamine-cured epoxy resins, dicyandiamide-cured epoxy resins, dibasic acid hydrazide-cured epoxy resins, polybasic acid anhydride-cured epoxy resins, or cured by ring-opening of epoxy groups are used. , so-called ring-opening polymerization cured epoxy resin systems, etc., but the requirements for the epoxy resin system as a prepreg matrix are that it be uniform, and that the resin impregnated into the fibrous reinforcing material must first have a viscosity for impregnation. It has a sufficiently low viscosity suitable for the following conditions, a long pot life, good stability of the prepreg itself, and a high curing speed during molding of this prepreg. However, in general, among polyamine-cured epoxy resin systems, those that use aliphatic polyamine as a curing agent have a short resin pot life and poor prepreg stability, while aromatic polyamine-cured systems have a long pot life, but the resin This is not preferable because the system is non-uniform, or even if it is homogeneous, the viscosity is high. In dicyandiamide curing systems and dibasic acid hydrazide curing systems, the curing agent and resin tend to be non-uniform systems, and in addition, it is difficult to reduce the viscosity when impregnating the fibrous reinforcing material, which is undesirable. Further, in a curing system based on ring-opening polymerization of an epoxy group, it is difficult to obtain a stable B-stage state and to reduce the viscosity necessary for impregnating the fibrous reinforcing material, which is not preferable. Furthermore, among polybasic acid anhydride curing systems, when a liquid acid anhydride, which is widely used as a curing agent for such epoxy resins, is used, it gives a relatively low viscosity product and is uniform in composition with the resin. mixed with,
Furthermore, the long pot life and stable B-stage state of the cured system make it desirable as a prepreg matrix, but it still has a sufficiently low viscosity to be suitable for impregnating fibrous reinforcement. In order to reduce the viscosity, it is necessary to use only low-viscosity liquid epoxy resins, and to use high-viscosity or solid epoxy resins, which can be said to be preferable from the viewpoint of various physical properties, it is necessary to use so-called It becomes absolutely necessary to use a diluent in combination. However, although the use of such diluents makes it possible to lower the viscosity, on the other hand, physical properties such as heat resistance, moisture resistance, and mechanical properties deteriorate; Even when using epoxy resin, when a resin composition of this and liquid polybasic acid anhydride is used as a matrix,
In general, because the reaction rate is low, the melt viscosity during hot compression molding becomes too low, causing the matrix to flow out, resulting in a poor yield, and furthermore, the hot compression molding time becomes longer, resulting in poor productivity. However, based on the above-mentioned technical background, the present inventors have conducted extensive research on prepregs using polybasic acid anhydride curing systems, particularly solvent-free polybasic acid anhydride curing epoxy resin systems, as matrices. By using a basic acid anhydride-cured epoxy resin system and an epoxy vinyl ester resin in the prepreg matrix, all the drawbacks of the conventional prepreg using a polybasic acid anhydride-cured epoxy resin as a matrix are solved, and it has excellent workability and The present invention was completed by discovering that a prepreg having good moldability and various physical properties can be obtained. That is, in the present invention, the average epoxy equivalent is 100 to
An epoxy resin composition (A) prepared by blending a polybasic acid anhydride and a curing accelerator with a solvent-free liquid epoxy resin in the range of 400 and an epoxy vinyl ester resin (B), ) weight ratio is 95/5 to 30/70
A resin composition () that is blended so that
and a fibrous reinforcing material () as essential components, and which is particularly excellent in workability and heat compression moldability. The resin (B) can be obtained by impregnating it with the reinforcing material (), which is another essential component, and aging it at room temperature or a higher temperature. It may be used in the form of a resin composition by incorporating an initiator therein. Typical epoxy resins constituting the epoxy resin composition (A) in the present invention include epoxy resins obtained from epichlorohydrin or β-methylepichlorohydrin and bisphenol A, bisphenol F, or bisphenol S. ; Polyglycidyl ethers of phenol or alkylphenol novolak resin; ethylene glycol, propylene glycol, polyethylene glycol, polypropylene glycol, neopentyl glycol, glycerin, trimethylolethane, trimethylolpropane or bisphenol A with ethylene oxide or propylene oxide addition Polyglycidyl ethers of polyhydric alcohols such as polyhydric alcohols; polyglycidyl esters of polycarboxylic acids such as adipic acid, phthalic acid, hexahydrophthalic acid or dimer acid; by epoxidizing cyclohexene or its derivatives with peracetic acid etc. The resulting cyclohexene-based epoxy compounds (3,
4-epoxy-6-methyl-cyclohexyl-
3,4-epoxy-6-methylcyclohexanecarboxylate, 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate, 1-epoxyethyl-3,4-epoxycyclohexane, etc.), cyclopentadiene or dicyclopentadiene or cyclopentadiene-based epoxy compounds (cyclopentadiene oxide, dicyclopentadiene oxide, 2,3-epoxycyclopentyl ether, etc.) obtained by epoxidizing their derivatives with peracetic acid, limonene dioxide, or tetrabromobis These include diglycidyl ether of phenol A or glycidyl ether ester of hydroxybenzoic acid, among which the epoxy resin used as the epoxy resin has an average epoxy equivalent of about 100 to 100.
400 or appropriately combined in the form of a mixture of two or more to give an epoxy equivalent within this range,
And it is a solvent-free liquid at room temperature. Typical polybasic acid anhydrides in the present invention include phthalic anhydride, hexahydrophthalic anhydride, tetrahydrophthalic anhydride,
Methylhexahydrophthalic anhydride, methyltetrahydrophthalic anhydride, nadic anhydride, methyl nadic anhydride, trimellitic anhydride, pyromellitic anhydride, maleic anhydride, succinic anhydride, itaconic anhydride, citraconic anhydride, dodecenyl succinic anhydride, Chlorendic anhydride, benzophenonetetracarboxylic anhydride, cyclopentatetracarboxylic anhydride, 5-(2,5-dioxotetrahydrofuryl)-3-methyl-3-cyclohexene-1,2-dicarboxylic acid, ethylene glycol bistri These include anhydrous mellitate and anhydrous glycerin trimellitate, and these may be used alone or in a mixture of two or more. In addition, typical curing accelerators used in the present invention include diethylamine, triethylamine,
diisopropylamine, monoethanolamine,
Diethanolamine, triethanolamine, methylethanolamine, methyldiethanolamine, monoisopropanolamine, nonylamine, dimethylaminopropylamine, diethylaminopropylamine, α-benzyldiethanolamine, 2,4,6-tris-dimethylaminomethylphenol or its tri-2 -Ethylhexylate, 2-dimethylaminomethylphenol, pyridine, piperidine, N-aminopropylmorpholine, 1,8-diazabicyclo(5,4,
0) Undecene-7 or it and phenol, 2
- Various amines such as ethylhexanoic acid, oleic acid, diphenylphosphous acid or salts with organic phosphorous acids; 2-methylimidazole, 2-isopropylimidazole, 2-undecylimidazole, 2-phenylimidazole, 2-phenyl ―
4-methylimidazole, 1-benzyl-2-methylimidazole, complexes of imidazole with metal salts such as Cu, Ni or Co, cyanoethylation type imidazole obtained by reacting 2-methylimidazole with acrylonitrile, or with them. imidazoles such as adducts with trimellitic acid or reactants with dicyandiamide;
BF ₃ -monoethanolamine, BF ₃ -benzylamine, BF 3 -dimethylaniline, BF ₃ -triethylamine, BF _{3 -n} -hexylamine, BF ₃ -
BF ₃ -amine complexes such as 2,6-diethylaniline, BF ₃ -aniline or BF ₃ -piperidine; amine imide compounds starting from 1,1-dimethylhydrazine; phosphorus compounds such as triphenylphosphite or octylic acid Examples include organic acid metal salts such as tin. Furthermore, the epoxy vinyl ester resin as used in the present invention refers to the above-mentioned various epoxy resins alone, such as bisphenol type epoxy resins or novolac type epoxy resins, and particularly to these bisphenol type or novolac type epoxy resins. Each of these resins alone or a mixture of various types, especially a mixture of both bisphenol type and novolak type resins, and an unsaturated monobasic acid as described below are reacted in the presence of an esterification catalyst. This refers to a resin obtained by dissolving the epoxy vinyl ester obtained by dissolving in a polymerizable vinyl monomer, if necessary. Here, typical unsaturated monobasic acids include acrylic acid, methacrylic acid, cinnamic acid, crotonic acid, monomethyl maleate, monopropyl maleate, monobutyl maleate, sorbic acid, and mono(2-ethylhexyl). These include malate, which can be used alone or in combination of two or more. The reaction between these epoxy resins and unsaturated monobasic acids is carried out by a conventionally known method, and if necessary, the epoxy vinyl ester resin obtained in this way can be dissolved in a conventional polymerizable vinyl monomer to form a stable resin solution. However, typical examples of polymerizable vinyl monomers include styrene and its derivatives such as styrene, vinyltoluene, t-butylstyrene, chlorostyrene, or divinylbenzene; 2-ethylhexyl (meth)acrylate, uralyl ( Low boiling ester monomers of (meth)acrylic acid such as meth)acrylate, 2-hydroxyethyl (meth)acrylate or 2-hydroxypropyl (meth)acrylate; or trimethylolpropane tri(meth)acrylate, diethylene glycol di(meth)acrylate acrylate, (meth)acrylates of polyhydric alcohols such as 1,4-butanediol di(meth)acrylate or 1,6-hexanediol di(meth)acrylate, etc., which may be used alone or in combination of two or more kinds. Used as a mixture. When preparing the epoxy vinyl ester resin constituting the resin (B) in the present invention, polymerization is carried out for the purpose of preventing gelation during resin preparation and for adjusting the storage stability or curability of the resulting resin. It is recommended to use an inhibitor, and typical examples of such polymerization inhibitors include hydroquinones such as hydroquinone, pt-butylcatechol, and mono-t-butylhydroquinone; hydroquinone monomethyl ether, di- t-p-
Phenols such as cresol; quinones such as p-benzoquinone, naphthoquinone, p-torquinone; or copper salts such as copper naphthenate. By the way, both (B) component resins obtained in this way can be sufficiently cured by simply heating without using a catalyst, but if necessary,
Benzoyl peroxide, p-menthane hydroperoxide, t-butyl perbenzoate, 1,1-di-t-butyl peroxy-3,
Organic peroxides such as 3,5-trimethylcyclohexanone can be used as polymerization initiators,
In such a case, the component (B) in the present invention can be considered as a resin composition consisting of a resin and a polymerization initiator. The above-mentioned epoxy resin composition (A) is prepared by blending a polybasic acid anhydride and a curing accelerator with a solvent-free liquid epoxy resin having a specific average epoxy equivalent weight, and an epoxy vinyl ester resin (B). The weight ratio of the resin composition (B) to the resin composition (B) containing a polymerization initiator, if necessary, may be selected as appropriate depending on the required properties and working conditions. If the ratio of component B) becomes too large, the physical properties will be close to those of the epoxy vinyl ester resin itself, and the characteristics of the polybasic acid anhydride-cured epoxy resin, which is component (A), such as low curing shrinkage, will be lost. This will result in damage. Therefore, the weight ratio of both components (A) to (B) is 95/5 ~
A range of 30/70, preferably 95/5 to 70/30 is suitable. Component (A) and component (B) may be prepared separately and then mixed together, or component (B) may be added to the epoxy resin or polybasic acid anhydride in component (A) first.
It is also possible to mix the epoxy vinyl ester resin and, if necessary, a polymerization initiator, and then add the remaining component (A), so the order in which each component compound is blended is not limited. Further, it is also possible to add conventional additives such as an internal mold release agent or a pigment to the resin composition () constituting the prepreg of the present invention thus obtained. On the other hand, typical examples of the fibrous reinforcing material as the component () constituting the prepreg of the present invention include glass fiber, carbon fiber, and aromatic polyamide fiber. In terms of raw materials, there are E-glass, C-glass, A-glass, S-glass, etc., but any of these types can be applied in the present invention. Next, carbon fibers include those manufactured using polyacrylonitrile fibers, cellulose fibers, pitch, aromatic hydrocarbons, or carbon black as raw materials, and aromatic polyamide fibers are polyfunctional aromatic fibers. It is made from a polymer having an amide bond through the reaction of a group amine and an aromatic polybasic acid. Typical polymers include poly-p-phenylenetetraphthalamide and poly-p-aminobenzamide. can be mentioned. These fibrous reinforcing materials () are classified into roving, chopped strand pine, continuous pine, cross, roving cloth, surficing pine, and chopped strand depending on their shape. The type and shape are appropriately selected depending on the intended use and performance of the molded product, and two or more types or shapes may be used in combination, if necessary. In obtaining the prepreg of the present invention, the volume ratio of the fibrous reinforcing material () is 30 to 70% of the prepreg.
It is appropriate to fall within the following range. In order to obtain the prepreg of the present invention, the reinforcing material () is impregnated with the resin composition () at room temperature or higher temperature to form a sheet, and then a sandwiched sheet is formed using a release sheet. No, it is preferable to similarly age at room temperature or a higher temperature to increase the viscosity to the B-stage state. The prepreg of the present invention obtained by such a method is
Next, a desired molded product is obtained by heating and compression molding, but if necessary, post-curing may be performed after releasing the molded product from the molding die. Next, the present invention will be specifically explained using Examples and Comparative Examples. In the following, all parts and percentages are based on weight unless otherwise specified. Example 1 16.9 parts of an epoxy resin with an epoxy equivalent of 190 obtained by the reaction of bisphenol A and epichlorohydrin, 26.5 parts of an epoxy resin with an epoxy equivalent of 370 obtained by the reaction of tetrabromobisphenol A with epichlorohydrin, methyl Consists of 26.6 parts of tetrahydrophthalic anhydride, 0.7 parts of benzyldimethylamine, methacrylate (60%) of an epoxy resin with an epoxy equivalent of 370 obtained by reacting tetrabromobisphenol A with epichlorohydrin, and styrene monomer (40%). 30 parts of epoxy vinyl ester resin and "Perhexa 3M" (polymerization initiator manufactured by NOF Corporation)
A resin composition was prepared by mixing 0.6 parts. The viscosity of this stuff is 650cps and the bromine content is 20%
It was hot. Next, 60 parts of glass cloth was impregnated with 40 parts of this resin composition and then aged at 40°C for about 30 hours to obtain a tack-free prepreg. Thereafter, nine sheets of this prepreg were stacked with copper foil and heated and compressed at 160° C. for 30 minutes under a pressure of 40 kg/cm ² . Table 1 shows the physical properties of the copper-clad laminate thus obtained. Comparative Example 1 20.8 parts of an epoxy resin with an epoxy equivalent of 190 obtained by the reaction of bisphenol A and epichlorohydrin, tetrabromobisphenol A
A resin composition was prepared by mixing 42.2 parts of an epoxy resin having an epoxy equivalent of 370 obtained by the reaction between the epoxy resin and epichlorohydrin, 37.0 parts of methyltetrahydrophthalic anhydride, and 0.6 parts of benzyldimethylamine. After impregnating 60 parts of glass cloth with 40 parts of the resulting resin composition with a viscosity of 2100 cps and a bromine content of 20%, it was aged at 40°C for about 40 hours to obtain a tack-free prepreg. Ta. Thereafter, a copper-clad laminate for comparison was obtained in the same manner as in Example 1, except that this prepreg was used. The results of various physical properties of this laminate are shown in Table 1. Comparative Example 2 This example concerns the preparation of a comparative copper clad laminate using a solvent-based dicyandiamide cured epoxy resin system commonly used for flame retardant printed circuit boards. First, the bromine content is 21% and the epoxy equivalent is obtained by reacting bisphenol A, tetrabromobisphenol A, and epichlorohydrin.
485 epoxy resin in methyl ethyl ketone solution (non-volatile content = 80%), 34 parts of acetone, 4 parts of dicyandiamide and 0.2 parts of dimethylbenzylamine were dissolved in 30 parts of methyl cellosolve. A resin composition was obtained by mixing with a curing agent solution. Next, a glass cloth was impregnated with this resin composition, and then aged at 160°C for 5 minutes to obtain a tack-free prepreg. Thereafter, a copper-clad laminate was obtained in the same manner as in Example 1, except that the heating compression time was changed to 1 hour and the prepreg of this example was used. Table 1 shows the physical properties of this laminate.

[Table] Example 2 100 parts of an epoxy resin with an epoxy equivalent of 190 obtained by the reaction of bisphenol A and epichlorohydrin, 87 parts of methyltetrahydrophthalic anhydride and 1 part of benzyldimethylamine, and separately phenol・Epoxy resin methacrylate with an epoxy equivalent of 182 obtained by the reaction of novolac resin and epichlorohydrin (70%)
and 46 parts of epoxy vinyl ester resin consisting of styrene monomer (30%) and "Perhexa 3M"
A resin composition was prepared by mixing 0.9 parts of Next, 30 parts of this resin composition was impregnated into 70 parts of carbon fiber roving to form a unidirectional sheet-like product, which was then aged at 40°C for about 40 hours to obtain a prepreg. After that, three sheets of this prepreg were heated and compressed (50Kg/cm ² , 160°/6 minutes), and then
Post-curing was carried out at 170° C. for 1 hour in an electric dryer. The physical properties of the molded product thus obtained were as follows. Bending strength 192Kg/ ^mm2 Bending modulus 13600 Interlaminar shear strength 9.2 Tensile strength 188 Tensile modulus 14000 Example 3 40 parts of the resin composition obtained in Example 2 were cut into pieces with a cut length of 1 inch. After impregnating it into Pudostrand glass, it was aged at 40° C. for about 30 hours to obtain a tack-free and bendable prepreg having a hardness of 75 to 85 on the Shore A hardness tester. Thereafter, molded products were obtained in the same manner as in Example 2, except that this prepreg was used. Next, the physical properties of this molded product were evaluated according to JIS standards, and the properties were as follows. Bending strength 47Kg/ ^cm2 Flexural modulus 1580 Tensile strength 26 Tensile modulus 1640 Elongation 2.0% Comparative example 3 Novolac type epoxy resin obtained from phenolic novolac resin and epichlorohydrin, methacrylate, styrene monomer and A resin composition was prepared in the same manner as in Example 2, except that "Perhexa 3M" was not used at all. Next, 40 parts of this resin composition was added to a cut length of 1.
A tack-free and bendable prepreg obtained by impregnating 60 parts of inch chopped strand glass and aging it at 40℃ for about 40 hours to have a hardness of 75 to 85 on the Shore A hardness tester. I got it. Thereafter, molding was carried out in the same manner as in Example 3, except for using this prepreg for comparison. However, there was a lot of matrix flowing out, and there were many bubbles left in the molded product. Moreover, the molded product deformed during cooling to room temperature after being released from the mold, and was not suitable for evaluation of physical properties. Example 4 40 parts of the resin composition obtained in Example 3 was impregnated into 60 parts of a continuous mat of glass fiber, and then aged at 40°C for about 40 hours to obtain a prepreg. Next, a molded product was obtained in the same manner as in Example 2 except that three sheets of this prepreg were used. The physical properties of this molded product were as follows. Volume resistivity 6×10 ¹⁵ Ω・cm Volume resistivity after 2 hours of boiling 2×10 ¹⁴ 〃 Bending strength 52Kg/mm ²

【table】

Claims (1)

[Claims] 1 () An epoxy resin composition (A) obtained by blending a polybasic acid anhydride and a curing accelerator with a solvent-free liquid epoxy resin having an average epoxy equivalent of 100 to 400; A resin composition comprising a vinyl ester resin (B) in a weight ratio of (A) to (B) of 95/5 to 30/70, and () a fibrous reinforcing material as an essential component. A prepreg that has excellent workability and compression moldability.