JPS644531B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for manufacturing various laminates such as copper-clad laminates for printed wiring, and its purpose is to:
Compared to conventional methods of manufacturing laminates that require solvent coating and long curing times, this method is able to provide laminates with superior properties using a solvent-free, fast-curing manufacturing method that saves resources and energy. It is. Conventionally, electrically insulating laminates have been mainly manufactured by a so-called dry method. In other words, epoxy resin, curing agent, curing accelerator, etc. are dissolved in a solvent,
By uniformly mixing the varnish, impregnating it into a base material such as glass cloth, and heating and drying it, B.
A laminate is obtained by making stage prepreg and then heating and pressurizing it. However, according to this method, it is necessary to remove the solvent contained in the varnish during the prepreg manufacturing process, which generates a large amount of solvent vapor during this process, which not only significantly deteriorates the working environment but also causes fires and explosions. There is also a danger of Furthermore, since it is necessary to go through a heating process to remove the solvent and it is necessary to store it as a prepreg, a latent curing agent such as dicyandiamide is used, so when heating and pressurizing it, It has the disadvantage of requiring long pressing times, typically 60 to 90 minutes. Furthermore, when attempting to create a solvent-free resin composition using dicyandiamide, uniform dispersion cannot be achieved because dicyandiamide has poor compatibility with epoxy resins. Therefore, even if a laminate is made using this, the curing is not uniform and brown spots are likely to occur. In view of these points, the present inventors conducted various studies including the combination of an epoxy resin and a curing agent, the method of impregnating a base material with a resin composition, and as a result, arrived at the present invention.
The present invention uses a cycloaliphatic amine as a curing agent for an epoxy resin having an average of two or more epoxy groups per molecule, and in order to make it a solvent-free system, each is uniformly mixed in liquid form to form a solvent-free resin composition. The present invention relates to a method for producing a solvent-free laminate in which a base material is impregnated with this solvent-free resin composition and then heated and pressed. be. Next, the present invention will be explained in more detail. The epoxy resin used in the present invention is not particularly limited as long as it has two or more epoxy groups per molecule on average, but examples include diglycidyl ether type epoxy resin of bisphenol A, butadiene diepoxide, 4,4'-di(1,2-epoxyethyl) diphenyl ether, 4,4'-di(epoxyethyl) biphenyl, diglycidyl ether of resorcinol, diglycidyl ether of phloroglycin, triglycidyl p-aminophenol Ether, 1,3,5-tri(1,2-epoxyethyl)benzene, 2,2',4,4'-tetraglycidoxybenzophenone, tetraglycidoxytetraphenylethane, phenol formaldehyde novolac polyglycidyl ether,
Triglycidyl ether of trimethylolpropane, polyglycidyl ether of cresol formaldehyde novolak, triglycidyl ether of glycerin, diglycidyl ether type epoxy resin of halogenated bisphenol A, polyglycidyl ether of halogenated phenol formaldehyde novolak, triglycidyl isocyanate Nurate, hydantoin epoxy resin (manufactured by Ciba Geigy, product names CY350, CY362), etc. The cycloaliphatic amine used as a curing agent contains 4,
4'-diaminodicyclohexylmethane, 3,3'-
Dimethyl 4,4'-diaminodicyclohexylmethane, 4,4'-diaminodicyclohexylethane,
Examples include menzendiamine and isophoronediamine. The amount of the epoxy resin and curing agent added is desirably 0.8 to 1.2 amine equivalents per 1 epoxy equivalent of the epoxy resin, and if it is outside this range, the properties of the cured laminate will be adversely affected. Preferably it is 1.0 amine equivalent. Since the solvent-free resin composition used in the present invention has a very short pot life, it is preferable to carry out the uniform mixing step, the substrate impregnation step, and the mold clamping step during heating and pressing in a short time. Furthermore, when attempting to manufacture a laminate using this resin composition using a conventional method using a solvent, the curing progresses too much during the heat drying process to remove the solvent.
It hardens in the prepreg state, making it impossible to manufacture a laminate. Note that the term "solvent-free resin composition" as used in the present invention means that an amount of solvent that would require a solvent removal step as in conventional methods is not used, and a trace amount of solvent may be used. Base materials include glass cloth, glass nonwoven fabric,
Any conventionally known base material such as paper or polyester cloth can be used. In addition to the above-mentioned epoxy resin and curing agent, a curing accelerator, modifier, filler, pigment, etc. may be added as necessary. As a method for uniformly mixing the epoxy resin and the curing agent in liquid form, it is preferable to first heat them until each becomes liquid. However, if it is liquid at room temperature, there is no need to heat it, and high-temperature heating that would cause immediate hardening during mixing is not appropriate. Next, suitable methods for uniformly mixing in a short time include a method of high-speed stirring using a stirring motor, a method of using a liquid resin metering and mixing discharge device, a method of using a reaction injector molding device, and the like. As a method for impregnating the base material with the solvent-free resin composition, the solvent-free resin composition may be applied onto one substrate, and then the required number of sheets may be stacked and heated and pressurized. The solvent-free resin composition may be applied, or the solvent-free resin composition may be applied between two substrates in a sandwich-like manner.
In addition, if the viscosity of the solvent-free resin composition is low even at room temperature, as in the case of using a low molecular weight liquid epoxy resin,
It is also possible to impregnate a base material by raising the temperature to a temperature at which the viscosity is suitable for impregnation, and then immersing the base material in a solvent-free resin composition in the same manner as with a solvent-containing varnish. In the case of a solvent-free resin composition using a high molecular weight epoxy resin, due to its high viscosity, it may be impossible to impregnate the substrate without sufficiently proceeding with the reaction under atmospheric pressure. In the heating and pressing step after applying the solvent-free resin composition to the base material, the base material can be impregnated with the composition, so no inconvenience occurs. The heating and pressure forming method can be done by using the usual end plate, but in order to avoid going through the B stage state, it is necessary to insert a spacer between the end plates or to use a mold with edges. This is preferable because the uncured resin does not flow out and pressure is applied inside. In addition, in the conventional solvent-based laminate manufacturing method, it is usually necessary to press for 60 to 90 minutes as described above, whereas in the method of the present invention using a cycloaliphatic amine as a curing agent, the molding time is fast. Since it has hardening properties, it can be completely cured by pressing for 5 to 10 minutes, so it can be molded in a very short time. When manufacturing a laminate in this way, it is normal to stack metal foil such as copper on both sides or one side of the base material and heat and pressure mold it to make a metal foil-clad laminate. I can do without it. The metal foil used is copper foil, aluminum foil, etc. The present invention will be described in detail below using examples. However, the present invention is not limited to the following examples. Example 1 100 g of a brominated bisphenol A type epoxy resin manufactured by Ciba Geigy, trade name Araldite 8011 (epoxy equivalent: 490 g/eq) was heated and melted at 130°C.
Separately, 10.7 g of 4,4' diamino dicyclohexylmethane manufactured by Shin Nippon Rika, trade name Wandamine HM (amine equivalent: 52.6 g/eq), was heated and melted at 80°C. The heated Araldite 8011 was stirred at high speed using a stirring motor, and the heated Wondermine HM was quickly added. After stirring for 20 seconds, immediately remove a layered glass cloth (size
190mm x 270mm), apply the entire amount on top of 4 sheets, layer 4 sheets of glass cloth on top of that, and then apply 35μTAI on top of that.
One sheet of treated copper foil was stacked. Using a mold with an edge of 1.6 mm in height, pressing was performed at 170°C for 5 minutes to obtain a single-sided copper-clad laminate. Table 1 shows the properties of the solvent-free resin composition and the laminate. Example 2 83.6 g of Araldite 8011 and 16.4 g of highly brominated bisphenol A type epoxy resin manufactured by Dow Chemical Company, trade name DER-542 (epoxy equivalent: 375 g/eq) were added.
It was heated and melted at 130°C. Meanwhile Wondermin HM11.3
g was heated and melted at 80°C. Using these materials, a copper-clad laminate was obtained in the same manner as in Example 1. Table 1 shows the properties of the solvent-free resin composition and the laminate. Comparative Example 1 Solution A in which 100 parts by weight of Araldite 8011 was dissolved in 25 parts by weight of methyl ethyl ketone, Solution B in which 4 parts by weight of dicyandiamide was dissolved in 15 parts by weight of dimethylformamide and 15 parts by weight of methyl cellosolve, and 0.2 parts by weight of benzyldimethylamine. Part C was uniformly mixed at room temperature to prepare a solvent-containing varnish. A glass cloth was impregnated with this solvent-containing varnish and then dried in a hot air dryer at 160° C. for 4 minutes to remove the solvent, thereby obtaining a prepreg. Eight sheets of this prepreg and one sheet of 35 μTAI-treated copper foil were stacked, sandwiched between two mirror plates, and pressed at 170° C. for 90 minutes to obtain a copper-clad laminate. Table 1 shows the properties of the solvent-containing varnish and the laminate. When the pressing time was set to 5 minutes instead of 90 minutes, the resin was not yet fully cured and the resin adhered to the mirror plate. From the above Examples and Comparative Examples, it can be seen that the laminate according to the present invention can be produced without a solvent and can be cured quickly, and its properties are comparable to those of the laminate produced by the conventional method.

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Claims (1)

[Claims] 1. A solvent-free resin composition is prepared by uniformly mixing an epoxy resin having two or more epoxy groups per molecule and a cycloaliphatic amine as a curing agent in liquid form. A method for producing a solvent-free laminate, which comprises impregnating a base material with a solvent-free resin composition and then performing heating and pressure molding. 2. The method for producing a solvent-free laminate according to claim 1, wherein the cycloaliphatic amine is 4,4'diaminodicyclohexylmethane.