JPH0438771B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD The present invention relates to a method for producing a flame-retardant paper-based phenolic resin laminate that has excellent heat resistance and electrical properties, and exhibits little dimensional change during repeated heat treatments and moisture absorption treatments. BACKGROUND ART In recent years, printed circuit boards using laminates as insulating substrates have become denser and the number of finer circuits has increased, and at the same time, component mounting methods have also changed. For example, the use of surface mount components is increasing, and the bonding methods thereof tend to include heat treatment steps at higher temperatures than conventional methods when attaching components, such as adhesive curing by heating or cream solder reflow method. Furthermore, the mounting process is often automated, and in order to adapt to these processes, a high degree of dimensional accuracy has been required of the laminate. In addition, due to the requirements of safety standards such as UL standards, the demand for flame retardancy has become stronger, and the proportion of flame-retardant laminates has increased. In order to meet this demand, it has been known that heat resistance, electrical properties, flame retardance, etc. can be improved by pre-treating the paper base material with an aqueous solvent system, and a two-stage coating method has been developed. Therefore, a method has been adopted in which a paper base material is treated in advance with a solution of a phenolic resin initial condensate, a melamine resin initial condensate, or a mixture thereof in water or a mixed solvent of water and methanol. However, these conventionally used phenolic resins and melamine resins harden through a condensation reaction, so laminates can be damaged due to effects such as inclusion of condensed water during curing and heat shrinkage when laminates are heated. A sufficient effect was not obtained in terms of improving heat resistance or reducing dimensional fluctuations when subjected to a heating process. In addition, melamine resin, which has a great effect on flame retardancy, is only soluble in water and can only be used in combination with water-soluble substances. If you use
The types of resins that can be used in combination are limited to a relatively narrow range. On the other hand, epoxy resins generally do not release condensed water during curing compared to phenolic resins and melamine resins, and therefore have superior heat resistance, electrical properties, and moisture resistance. However, water, which has a large treatment effect on paper base materials,
It has low solubility in solvents such as methanol,
It has been difficult to use melamine resin in an aqueous solvent system simultaneously with melamine resin for treating paper base materials. Problems to be Solved by the Invention When an epoxy resin with excellent heat resistance, electrical properties, and moisture resistance is used in a solvent system such as acetone, toluene, or methyl ethyl ketone, which can normally be dissolved in it, these solvents have a higher resistance to water than water. Due to the low polarity, the expected improvement in properties is not necessarily seen due to the reduced treatment effect of the paper base material, and such solvent systems cannot be used in combination with melamine resin, and there is little effect on flame retardancy. In addition, there are many negative aspects to manufacturing, such as increased manufacturing costs, deterioration of the working environment, and increased exhaust gas. In view of these circumstances, the present invention makes it possible to use an epoxy resin with excellent properties in combination with a melamine resin in an aqueous solvent system that has a large treatment effect on paper base materials, and improves the heat resistance, electrical properties, and dimensions of the laminate. The aim is to reduce deterioration, improve flame retardancy, and eliminate the aforementioned manufacturing problems. Means for Solving the Problems The present invention has been made to achieve the above object, and is an aqueous solvent system that has a large treatment effect on paper base materials.
In order to simultaneously use an epoxy resin with excellent properties and a melamine resin with flame retardant properties, we emulsify them using water as a dispersion medium and a nonionic surfactant, and pre-impregnate the paper base material with the emulsion. After the treatment, the coated paper obtained by further coating and drying a phenol resin is laminated and molded to obtain a laminate. In addition, the combined invention with respect to the above-mentioned specified invention simultaneously uses a brominated epoxy resin with excellent properties in an aqueous solvent system that is highly effective in treating paper base materials, and a melamine resin with flame retardant properties. Emulsion is formed using water as a dispersion medium and a nonionic surfactant, and the paper base material is pre-impregnated with the emulsion, and then a phenolic resin is coated and dried to form a coated paper, which is then laminated. Characterized by obtaining a board. Function α-cellulose, which accounts for more than 95% of the paper base material,
Its fibrous structure is maintained by strong intermolecular hydrogen bonds. In order to effectively treat the paper base material and enhance the impregnation effect of the resins used for impregnation coating, it is necessary to break the hydrogen bonds, swell the paper base material, and infiltrate the resin into the fiber structure. It is necessary to do so. The present invention is a glycidyl ether type epoxy resin of bisphenol A diglycidyl ether type epoxy resin and novolak resin, which does not release condensed water during heat curing, does not easily shrink, and has excellent heat resistance, electrical properties, and moisture resistance. By emulsifying the melamine resin initial condensate with water as a dispersion medium, it becomes possible to use the epoxy resin and the melamine resin initial condensate simultaneously, and to eliminate the large amount of water present in the system. In addition to exhibiting the impregnating effect of epoxy resin, the above-mentioned excellent properties of epoxy resin and the flame retardant effect of melamine resin improve the heat resistance and electrical properties of the laminate, and reduce dimensional changes after heat treatment. It is possible to reduce flame retardancy and improve flame retardancy. In addition, in the combined invention, by using as the epoxy resin a diglycidyl ether type epoxy resin of brominated bisphenol A and a glycidyl ether type epoxy resin of brominated novolak resin, either alone or in combination, the flame retardant effect is even more remarkable. become. Examples The epoxy resin used in the present invention is preferably a diglycidyl ether type epoxy resin of bisphenol A, a glycidyl ether type epoxy resin of novolak resin, or a mixture thereof from the viewpoint of heat resistance, and the epoxy equivalent can be arbitrarily selected. It is. As the initial condensate of melamine resin, mononuclear bodies of mono, g, tri, tetra, penta, and hexermethylol melamine are desirable from the viewpoint of impregnation into paper base materials and dispersibility when formed into an emulsion. Nonionic surfactants are used for laminates that require electrical insulation, but polyoxyethylene larylether, polyoxyethylene larylether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, and polyoxyethylene larylether are used as surfactants. Oxyethylene higher alcohol ether, polyoxyethylene nonylphenol ether, sorbitan monolaurate, sorbitan monopalmitate, polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monopalmitate, polyoxyethylene sorbitan monostearate, polyoxyethylene Sorbitan tristearate, polyoxyethylene sorbitan monooleate, polyoxyethylene sorbitan trioleate, polyethylene glycol monolaurate, polyethylene glycol monostearate, polyethylene glycol distearate, polyethylene glycol monoolecoat, polyoxyethylene sorbitol tetraoleate Those with an isohydrophilic/lipophilic balance, so-called HLB, in the range of 8 to 19 can be used. The amount of nonionic surfactant used is preferably in the range of 1 to 5 parts per 100 parts of the solid weight of the epoxy resin. If the amount is less than 1 part, it is difficult to make a good emulsion. In order to produce a good emulsion within the above-mentioned relatively small usage range, it is effective to use 2 to 5 types of nonionic surfactants with different HLBs in combination. It is also effective to use a small amount of a water-soluble polymer such as hydroxyethyl cellulose, carboxymethyl cellulose, or polyvinyl alcohol, as long as it does not inhibit crosslinking of the epoxy resin. Furthermore, the combined use of aromatic hydrocarbon solvents such as toluene, xylene, and benzene is also effective in producing and stabilizing emulsions. However, if the amount of the solvents is too large relative to water, which is the dispersion medium, separation of the solvents from the aqueous layer will occur. It is desirable to keep it below. For paper substrates treated with emulsion,
Furthermore, the phenolic resin containing flame retardant to be coated includes tung oil-modified phenolic resin or alkyl-modified phenolic resin, brominated epoxy resin,
Appropriate combinations of brominated flame retardants such as brominated diphenyl ether and tetrabromobisphenol A, and phosphorus flame retardants such as triphenyl phosphate, tricresyl phosphate, and tricylesyl phosphate were selected and mixed. can use things. If the solid weight of the melamine resin initial condensate exceeds 50 parts of the total solid weight of 100 parts of the epoxy resin and melamine resin initial condensate, the amount of the epoxy resin and melamine resin initial condensate used will be In addition, the dimensional shrinkage of the laminate after the heating process increases due to the influence of the post-shrinkage of the melamine resin when heated. Furthermore, if the solid weight of the melamine resin initial condensate is less than 10 parts, the flame retardance will decrease. In addition, from the viewpoint of heat resistance, the brominated epoxy resin used in the combined invention is preferably a diglycidyl ether type epoxy resin of brominated bisphenol A, a glycidyl ether type epoxy resin of brominated novolak resin, or a mixture thereof. The equivalent amount can be selected arbitrarily. These are used in the same way as for specific inventions. Examples of the present invention will be described. Example 1 In 1455 g of water, 3 g each of polyoxyethylene nonylphenol ethers with HLB of 6, 9, and 11 as nonionic surfactants, 1 g of hydroxyethyl cellulose, and 60 g of trimethylolmelamine as dispersion stabilizers are dissolved. 78 g of toluene was added to 240 g of bisphenol A diglycidyl ether type epoxy resin having an epoxy equivalent of 400, stirred and dissolved uniformly, and then the nonionic surfactant, dispersion stabilizer, and melamine resin initial condensate were dissolved therein. It was dropped into water little by little while stirring to obtain a water-dispersed emulsion of epoxy resin and trimethylolmelamine with a total solid content of 15%. This emulsion was coated on 10 mils kraft paper and dried at 120°C for 15 minutes to obtain coated paper with a resin content of 15%. The resin amount was defined and calculated as follows. Resin amount (%) = Weight of coated paper after coating and drying - Weight of untreated paper base material / Weight of coated paper after coating and drying x 100 Furthermore, on the coated paper obtained in this way, A tung oil modified phenolic resin, a diglycidyl ether type epoxy resin of brominated bisphenol A with an epoxy equivalent of 400, and a tung oil modified phenolic resin containing a flame retardant with a solid weight ratio of triphenyl phosphate of 70/22.5/7.5, respectively. It was coated and dried by heating to a predetermined degree of curing to obtain coated paper with a resin content of 50%. The tung oil-modified phenolic resin used here was obtained as follows. 720g of tung oil in a three-necked flask,
m-cresol 580g, para-toluenesulfonic acid
After 1 hour of reaction at 80℃, 500g of phenol, 450g of 86% paraform, and 35g of 25% ammonia water were added and the reaction proceeded at 80℃. When the gel time reached 6 minutes, the mixture was dehydrated and concentrated, and then methanol was added to adjust the resin solid content to 50%. 8 sheets of coated paper and adhesive on one side of the paper
35 μ thick copper foils were stacked together and heated and pressed to obtain a single-sided copper-clad laminate with a thickness of 1.6 mm. Example 2 HLB was added as a nonionic surfactant to 1455 g of water.
6. Dissolve 2.5 g each of polyoxyethylene stearyl ether (10 and 13), 2 g of polyvinyl alcohol with a molecular weight of 1700 and saponification number of 88% as a dispersion stabilizer, and 120 g of trimethylolmelamine. Add 78 g of toluene to 180 g of a glycidyl ether type epoxy resin of novolac resin with an epoxy equivalent of 300, stir and dissolve uniformly, and then add this to the water in which the nonionic surfactant, dispersion stabilizer, and melamine resin initial condensate have been dissolved. The mixture was added dropwise little by little while stirring to obtain a water-dispersed emulsion with a solid content of 15% in the same manner as in Example 1. Hereinafter, a single-sided copper-clad laminate having a thickness of 1.6 mm was obtained using the same tung oil-modified phenol resin containing a flame retardant as in Example 1. Example 3 To 1455 g of water, 2 g each of sorbitan monopalmitate, polyoxyethylene sorbitan monoate, and polyoxyethylene lauryl ether with HLB of 6, 10, and 16 as nonionic surfactants, 1 g of hydroxyethyl cellulose as a dispersion stabilizer, Polyvinyl alcohol with a molecular weight of 1700 and a saponification number of 88%
Dissolve 1g, trimethylolmelamine 150.
75g of bisphenol A diglycidyl ether type epoxy resin with an epoxy equivalent of 200, epoxy equivalent
Add 60 g of doluene to 75 g of glycidyl ether type epoxy resin of Novolac resin No. 400, stir and dissolve uniformly, and then add this to the nonionic surfactant,
A dispersion stabilizer and a melamine resin initial condensate were dissolved in water, which was added dropwise little by little while stirring to obtain a water-dispersed emulsion having a solid content of 15% in the same manner as in Example 1. Thereafter, a single-sided copper-clad laminate having a thickness of 1.6 mm was obtained in the same manner as in Example 1. Comparative Example 1 548 g of phenol, 508 g of 86% paraform, and 72 g of triethylamine were put into a three-necked flask, and 70
The reaction was allowed to proceed at ℃ until the gel time of the reaction product on a heating plate at 160℃ reached 5 minutes, then cooled and adjusted with methanol so that the resin solid content was 50%, and the phenolic resin initial condensate was I got it. After dissolving 90 g of trimethylol melamine in 600 g of water, 891 g of methanol was added, stirred and mixed uniformly, and then 420 g of the phenolic resin initial condensate was added, and this solution was coated on 10 mils kraft paper.
It was dried at 120°C for 15 minutes to obtain coated paper with a resin content of 15%. Hereinafter, using the same tung oil modified phenol resin containing the same flame retardant as in Example 1, the thickness was 1.6 mm.
A single-sided copper-clad laminate was obtained. Table 1 shows the characteristics test results of the single-sided copper-clad laminates of Examples 1 to 3 and Comparative Example 1.

[Table] Example 4 In 1455 g of water, dissolve 3 g each of polyoxyethylene phenol ethers with HLB values of 6, 9, and 11 as nonionic surfactants, 1 g of hydroxyethyl cellulose, and 60 g of trimethylolmelamine as dispersion stabilizers. Brominated bisphenol A diglycidyl ether type epoxy resin with epoxy equivalent of 400
Add 78 g of toluene to 240 g, stir and dissolve uniformly, and then drop this little by little into the water in which the nonionic surfactant, dispersion stabilizer, and melamine resin initial condensate were dissolved while stirring to effect bromination. A water-dispersed emulsion of epoxy resin and trimethylolmelamine with a total solid content of 15% was obtained. This emulsion was coated on 10 mils kraft paper and dried at 120°C for 15 minutes to obtain coated paper with a resin content of 15%. Furthermore, the coated paper thus obtained was coated with tung oil-modified phenol resin containing the same flame retardant as in Example 1, and heated and dried to a predetermined degree of hardening.
A 50% coated paper was obtained. 8 sheets of coated paper and adhesive on one side of the paper
35 μ thick copper foils were stacked together and heated and pressed to obtain a single-sided copper-clad laminate with a thickness of 1.6 mm. Example 5 1455 g of water, 2.5 g each of polyoxyethylene stearyl ether with HLB of 6, 10, and 13 as a nonionic surfactant, 2 g of polyvinyl alcohol with a molecular weight of 1700 and a saponite number of 88% as a dispersion stabilizer, and trimethylol melamine Dissolve 120g. 78 g of toluene was added to 180 g of a glycidyl ether type epoxy resin of brominated novolac resin with an epoxy equivalent of 300, stirred and dissolved uniformly, and then the nonionic surfactant, dispersion stabilizer, and melamine resin initial condensate were dissolved therein. It was added dropwise little by little into water with stirring to obtain a water-dispersed emulsion with a solid content of 15% in the same manner as in Example 1. Hereinafter, a single-sided copper-clad laminate with a thickness of 1.6 mm was obtained using the same tung oil-modified phenol resin containing a flame retardant as in Example 4. Example 6 As a nonionic surfactant in 1455g of water,
Sorbitan monopalmitate with HLB6.10, 16,
2g each of polyoxyethylene sorbitan monooleate and polyoxyethylene lauryl ether, 1g of hydroxyethyl cellulose as a dispersion stabilizer,
Dissolve 1 g of polyvinyl alcohol with a molecular weight of 1700 and a saponification number of 88% and 150 g of trimethylolmelamine. Brominated bisphenol A with epoxy equivalent weight 200
75g of diglycidyl ether type epoxy resin, 75g of glycidyl ether type epoxy resin of brominated novolak resin with epoxy equivalent of 400, and 60g of toluene.
After stirring and mixing uniformly, this was added dropwise little by little into water in which the nonionic surfactant, dispersion stabilizer, and melamine resin initial condensate were dissolved, with stirring, and the same procedure as in Example 4 was carried out. A water-dispersed emulsion with a solid content of 15% was obtained. Thereafter, a single-sided copper-clad laminate having a thickness of 1.6 mm was obtained in the same manner as in Example 4. Table 2 shows the property test results of the single-sided copper-clad laminates of Examples 4 to 6.

[Table] Effects of the Invention As shown in Tables 1 and 2, according to the present invention, epoxy resins that have conventionally been difficult to be used simultaneously in an aqueous solvent system to treat paper base materials. In addition, by forming a brominated epoxy resin and a melamine resin into an emulsion using water as a dispersion medium, it is possible to exhibit the water treatment effect on the paper base material and the excellent properties mentioned above of the epoxy resin and melamine resin. Therefore, it is effective in improving the heat resistance and electrical properties of the laminate, reducing dimensional changes during repeated heat treatment and moisture absorption treatment, and improving flame retardancy. In addition, by using an emulsion that uses water as a dispersion medium instead of conventionally used large amounts of organic solvents, we can reduce manufacturing costs, improve the working environment, and reduce pollution by reducing exhaust gas. be.

Claims (1)

[Scope of Claims] 1. Using a nonionic surfactant, the initial condensation product of a diglycidyl ether type epoxy resin of bisphenol A, a glycidyl ether type epoxy resin of novolak resin, alone or a mixture thereof, and a melamine resin is used as the epoxy resin. Solid weight ratio of melamine resin initial condensate to solid weight ratio of 90/10 to 50/50
An emulsion of a mixture containing water as a dispersion medium is coated and dried on a paper base material in advance, and then a phenolic resin containing a flame retardant is further coated and dried, and the obtained coated paper is laminated and molded. A method for producing paper-based phenolic resin laminates. 2 Using a nonionic surfactant, a melamine resin initial condensate of a diglycidyl ether type epoxy resin of brominated bisphenol A, a glycidyl ether type epoxy resin of brominated novolac resin, alone or a mixture thereof, is used to solidify the epoxy resin. Mold weight and melamine resin initial condensate in solid weight ratio
A coated paper obtained by coating and drying an emulsion of a mixture of 90/10 to 50/50 with water as a dispersion medium on a paper base material, and then coating and drying a phenolic resin containing a flame retardant. A method for producing a paper-based phenolic resin laminate, characterized by lamination molding.