JPH04314536A - Electric laminate - Google Patents

Abstract

PURPOSE:To heighten the impact resistance such as punchability of the laminate composed of cellulose fiber-base material, allyl ester resin and metallic foil. CONSTITUTION:The moisture content of the laminate from which metallic foil is removed is regulated in the range of 0.1-5.0wt.%, whereby the laminate has excellent punchability and electric characteristics as well as high mechanical strength.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention is applicable to electrical equipment, electronic equipment,
The present invention relates to electrical laminates for forming printed circuits used in communication equipment, etc.

0002

2. Description of the Related Art Various types of electrical laminates for forming printed circuits have been put into practical use. For those whose main component is cellulose fiber, a laminate is generally constructed of paper and phenol resin, or paper and unsaturated polyester resin, and metal foil is laminated on one or both sides of this laminate. An electrical laminate made of cellulose fibers and allyl ester resin has been proposed, for example, in Japanese Patent Application No. 1-255038.

[0003] When manufacturing an electrical laminate mainly composed of cellulose fibers and allyl ester resin,
A common method is to pre-impregnate cellulose fibers with a melamine resin and dry them, then impregnate this cellulose fiber base material with a curable resin liquid containing allyl ester resin as a main component, and then harden the impregnated cellulose fibers.

0004

[Problems to be Solved by the Invention] However, although the allyl ester resin laminate obtained in this manner has high mechanical strength, its impact resistance such as punching workability is insufficient, and mechanical Currently, it is a major challenge to obtain a laminate with a good balance of both mechanical strength and punching workability. Therefore, an object of the present invention is to provide an electrical laminate having high mechanical strength and excellent punching workability.

[0005]

[Means for Solving the Problems] As a result of intensive studies to achieve these objectives, the present inventors have developed a laminate consisting of a base material mainly composed of cellulose fibers, an allyl ester resin, and a metal foil. By adjusting the moisture content of the laminate from which the foil has been removed to within the range of 0.1 to 5.0% by weight, an electrical laminate with excellent mechanical strength and punching workability can be obtained. I discovered that it can be made.

The present invention will be explained in detail below.

[0007] Examples of the base material containing cellulose fiber as a main component in the present invention include kraft paper, linter paper, cotton paper, etc., and from the viewpoint of impregnability and quality, the density when air-dried is 0.3 to 0. .7 g/cm3, such as kraft paper.

When producing the laminate according to the present invention, a base material mainly composed of cellulose fibers is usually impregnated with a melamine resin and dried. It refers to the initial condensation products of , or those obtained by etherifying some or all of their methylol groups with alcohols having 5 or less carbon atoms. The amount of formaldehyde to be reacted with melamine or guanamines can be selected as appropriate, but usually 2.0% per mole of melamine or guanamines.
0 to 3.5 mol is preferred.

In the present invention, when impregnating and drying a substrate with a melamine resin, a higher fatty acid ester compound or a nonionic surfactant may be used in combination with the melamine resin. Higher fatty acid ester compounds include saturated or unsaturated fatty acids with 10 or more carbon atoms and 5 carbon atoms.
Refers to partially esterified products with the following glycols or polyols, which are usually solid at room temperature, such as stearic acid monoglyceride, stearic acid diglyceride,
Examples include, but are not limited to, oleic acid monoglyceride and oleic acid diglyceride. In addition, higher fatty acid ester compounds can be used not only alone but also in combination of two or more. Furthermore, higher fatty acid ester compounds can be used together with saturated or unsaturated fatty acids having 10 or more carbon atoms or saturated or unsaturated fatty acids having 5 or less carbon atoms. There is no problem even if a part of glycol or polyol is used in combination. Any commercially available nonionic surfactants can be used, such as polyoxyethylene alkyl ester, polyoxyethylene alkyl ether, polyoxyethylene alkylphenol ether, sorbitan alkyl ester, and polyoxyethylene sorbitan. Examples include alkyl esters and polyglycerin alkyl esters.

[0010] When impregnating and drying a base material mainly composed of cellulose fibers with melamine resin, the melamine resin is mixed with water, alcohols, ketones, etc. alone or in a mixed solvent to form a solution or suspension. Use with. After impregnating the base material with a solution or suspension of melamine resin, a drying treatment is performed, and during the drying treatment, a heat treatment is performed as necessary. The heat treatment is usually carried out at 80 to 180°C, but is not limited to this temperature. It is preferable that 5 to 40 parts by weight, preferably 10 to 30 parts by weight of melamine resin be attached to the substrate after impregnating and drying, based on 100 parts by weight of the substrate before impregnating and drying. If it is less than 5 parts by weight, the water resistance is insufficient, and if it exceeds 40 parts by weight, the punching workability is rather deteriorated.

[0011] The allyl ester resin as used in the present invention refers to a resin having an allyl ester group at the end of a saturated polyester composed of a saturated polybasic acid and a saturated polyhydric alcohol.

Examples of saturated polybasic acids include dibasic acids such as orthophthalic acid, orthophthalic anhydride, isophthalic acid, phthalic acids such as terephthalic acid, tetrahydrophthalic acid, methyltetrahydrophthalic acid, endomethylenetetrahydrophthalic acid, and methylendo. Hydrophthalic acids such as methylenetetrahydrophthalic acid, hexahydrophthalic acid, methylhexahydrophthalic acid, and their acid anhydrides; aliphatic dibasic acids such as malonic acid, succinic acid, glutaric acid, and adipic acid; tetrabromophthalic acid; , tetrachlorophthalic acid, chlorendic acid, and halogenated dibasic acids such as acid anhydrides thereof. Examples of trifunctional or higher-functional polybasic acids include trimellitic acid, pyromellitic acid, and acid anhydrides thereof. These can be used alone or in combination.

Examples of the saturated polyhydric alcohol include ethylene glycol, 1,2-propylene glycol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol, 1,4-cyclohexanedimethanol,
In addition to dihydric alcohols containing aliphatic, alicyclic or aromatic compounds such as paraxylene glycol, alcohols with the general formula HO (CHR
CH2 O)n H (R is H or Cm H2m+1,
(m is an integer of 1 to 5, n is an integer of 2 to 10) dihydric alcohols obtained by addition reaction of alkylene oxides such as ethylene oxide and propylene oxide. Examples of trihydric or higher polyhydric alcohols include aliphatic trihydric alcohols such as glycerin and trimethylolpropane, and tetrahydric or higher alcohols such as pentaerythritol and sorbitol. Further examples include aliphatic, alicyclic or aromatic halogenated polyhydric alcohols containing a halogen atom, such as dibromneopentyl glycol and tetrabromobisphenol A ethylene oxide adduct. These can be used alone or in combination.

The method for producing allyl ester resins is already known and is described, for example, in Japanese Patent Application No. 63-262217. For example, an allyl ester resin is produced by charging a diallyl ester of a saturated dibasic acid such as diallyl terephthalate and a saturated polyhydric alcohol together with a transesterification catalyst into a reactor and reacting the allyl alcohol while distilling off the allyl alcohol. As an industrially more effective method, instead of diallyl terephthalate, a dialkyl ester of a saturated dibasic acid such as dimethyl terephthalate is charged into a reactor together with allyl alcohol, a polyhydric alcohol, and a transesterification catalyst to produce by-products such as methanol. It can be obtained by reacting while distilling off the alcohol. Further, depending on the reaction temperature, a polymerization inhibitor such as hydroquinone may be allowed to coexist in the reaction solution. In this way, an allyl ester resin having an allyl ester group at the end of a saturated polyester can be produced.

In the present invention, the type of allyl ester resin that is impregnated into the base material which has been previously impregnated and dried with the melamine resin may be one type or a mixture of two or more types. By selecting various types of saturated polybasic acid and saturated polyhydric alcohol, it is possible to obtain an electrical laminate that meets the desired performance.

In the present invention, in addition to the allyl ester resin, the base material pre-impregnated and dried with the melamine resin may optionally contain a radically polymerizable crosslinking monomer or an additive type flame retardant compound containing bromine, chlorine, or phosphorus. It is also possible to impregnate and mold using a combination of inorganic flame retardants and the like.

Any known radically polymerizable crosslinking monomer can be used, including diallyl phthalates such as diallyl orthophthalate, diallyl isophthalate, and diallyl terephthalate;
Styrene, α-methylstyrene, p-methylstyrene,
Substituted styrenes such as p-chlorostyrene, bromustyrene, divinylbenzene; methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, (meth)acrylate
Acrylic acid or methacrylic acid esters such as lauryl acrylate, benzyl (meth)acrylate, brominated phenyl (meth)acrylate; ethylene glycol di(meth)acrylate, 1,4-butanediol di(meth)acrylate Acrylate, trimethylolpropane tri(meth)acrylate, diacrylated isocyanurate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate,
Glycerin di(meth)acrylate, neopentyl glycol di(meth)acrylate, bisphenol A di(
Vinyl polyfunctional acrylic acid or methacrylic acid esters such as meth)acrylate; polyurethane (meth)acrylate, polyether (meth)acrylate, epichlorohydrin-modified bisphenol A di(meth)acrylate, ethylene oxide-modified bisphenol A di(meth)acrylate, Vinyl polyfunctional oligoesters such as polyethylene glycol di(meth)acrylate and polypropylene glycol di(meth)acrylate are included.

There is no problem in using two or more types of crosslinking monomers in combination depending on the purpose. In the present invention, when a crosslinking monomer is blended, originally,
The viscosity of the allyl ester resin, which is a solid or viscous liquid, can be lowered, and the manufacturing process of the laminate can be simplified without going through a prepreg state using a solvent or the like.

Additive flame retardant compounds containing bromine, chlorine, or phosphorus refer to compounds having one or more bromine atoms, chlorine atoms, or phosphorus atoms in the molecule, and additive-type flame retardant compounds that do not undergo radical polymerization. Refers to aliphatic, alicyclic, and aromatic hydrocarbon compounds.

For example, substituted benzenes such as monobromobenzene, dibromobenzene, tribromobenzene, and bromochlorobenzene, substituted phenols such as bromophenol, dibromophenol, tribromophenol, and pentabromophenol, tetrabrom diphenyl ether, and pentabrom diphenyl ether. , substituted diphenyl ethers such as hexabrom diphenyl ether, octabrom diphenyl ether, decabrom diphenyl ether, tetrabromo bisphenol A, ethylene oxide adduct of tetrabromo bisphenol A, tetrachlorobisphenol A, brominated epoxy compounds, ethyl bromide, propyl bromide, butyl Bromide, amyl bromide, hexyl bromide, octyl bromide, lauryl bromide, dibromopropane,
Dibromodecane, tetrabromethane, tetrabromobutane, hexabromocyclododecane, dibromoneopentyl glycol, dibromopropanol, epibromohydrin, bromotoluene, pentabromotoluene, bromoxylene, bromonaphthalene, chlorinated paraffin, chlorinated polyethylene, Chlorinated polypropylene, perchloropentacyclodecane, chlorendic acid, tetrachlorophthalic anhydride, tetrabromophthalic anhydride, brominated polystyrene, polydibromophenyl oxide, trimethyl phosphate, triethyl phosphate, tributyl phosphate, trioctyl phosphate, triphenyl phosphate, Examples include, but are not limited to, tricresyl phosphate, tris(chlorethyl) phosphate, tris(dichloropropyl) phosphate, cresyl diphenyl phosphate, triphenyl phosphite, and the like. These can be used alone or in combination.

As the inorganic flame retardant, for example, antimony compounds such as antimony trioxide and antimony pentoxide, zinc borate, aluminum hydroxide, etc. can be used in combination.

[0022] In the present invention, the allyl ester resin can be cured using a general-purpose organic peroxide, and together with the organic peroxide or alone, it can be cured with a polymerization initiator that is sensitive to light, radiation, or an electron beam. Known polymerization initiators such as polymerization initiators can also be used.

Examples of organic peroxides include ketone peroxides such as methyl ethyl ketone peroxide and acetylacetone peroxide, 1,1-bis(t
-butylperoxy) 3,3,5-trimethylcyclohexane, peroxyketals such as n-butyl-4,4-bis(t-butylperoxy)valerate, t-butyl hydroperoxide, cumene hydroperoxide, Hydroperoxides such as p-menthane hydroperoxide, di-t-butyl peroxide,
Dicumyl peroxide, 2,5-dimethyl-2,5-
Dialkyl peroxides such as di(t-butylperoxy)hexane, diacyl peroxides such as lauroyl peroxide and benzoyl peroxide, di-
Peroxydicarbonates such as iso-propyl peroxydicarbonate, dimyristyl peroxydicarbonate, bis(4-t-butylcyclohexyl)peroxydicarbonate, t-butylperoxypivalate, t-butylperoxy- Examples include peroxy esters such as 2-ethylhexanoate and t-butylperoxybenzoate. These can be used alone or in combination of two or more depending on the type of resin and curing conditions.

In the present invention, the allyl ester resin may contain fillers, reinforcing materials, mold release agents, colorants, curing agents,
It is also possible to use accelerators, stabilizers, etc. in combination to further enhance the performance of the laminate.

The electrical laminate of the present invention can be manufactured according to known methods. That is, a base material that had been previously impregnated and dried with a melamine resin was impregnated with a curable resin liquid containing the above-mentioned allyl ester resin as a main component, a plurality of impregnated base materials were laminated, and an adhesive was applied on one or both sides in advance. Alternatively, an electrical laminate can be manufactured by stacking uncoated metal foils and heating, curing, and forming them without pressure or under pressure. At this time, the metal foil may be attached after the impregnated laminated base material is cured and molded.

As the metal foil, electrolytic copper foil intended for use in copper foil-clad laminates for electric circuits is commercially available, and it is preferable to use this from the viewpoints of corrosion resistance, etching properties, and adhesion. The invention is not limited to this. The thickness of the metal foil is preferably about 10 to 100 μm.

In order to effectively achieve adhesion between the metal foil and the resin-impregnated base material, it is preferable to use an adhesive, and the adhesive may be a liquid or adhesive that does not generate unnecessary side reaction products during the curing process. Semi-liquid ones are preferred. From this point of view, acrylate adhesives, epoxy adhesives, epoxy acrylate adhesives, isocyanate adhesives, or various modified adhesives thereof are used.

The thickness of the electrical laminate of the present invention varies depending on the type of substrate, the composition of the curable resin liquid, and the use of the laminate, but is usually 0.5 to 5 mm. Further, the proportion of the resin composition in the electrical laminate is 30 to 80% by weight.

Although the thus obtained laminate has high mechanical strength, its punching workability is insufficient, making it unsuitable as a material for printed wiring boards. As a result of the inventor's study, the punching workability of the laminate is determined by the moisture content in the obtained laminate,
In other words, it was found that there is a relationship with the water content. If the water content is below a certain value, punching workability will be reduced, and if it is excessive, other properties of the laminate, such as bending strength, soldering heat resistance, insulation properties, etc. will be reduced. In the metal foil-clad laminate of the present invention, the water content is 0.1 to 5.0% by weight, preferably 0.1 to 3% by weight, relative to the laminate from which the metal foil has been removed.
．． It is preferably within the range of 0% by weight.

[0030] Various methods can be used to adjust the moisture content, and are not particularly limited. For example, a method in which the cellulose fiber base material is humidified or dried before being impregnated with a curable resin liquid. , a method in which the curable resin liquid is humidified or dried in advance before curing, a method in which the curable resin liquid is humidified or dried during curing, a method in which the laminate is humidified or dried after the curable resin liquid is cured, etc.

[0031] There are various methods for measuring the moisture content, but the moisture content in the present invention is determined by measuring the moisture generated by heating two laminates of about 10 x 50 mm from which the copper foil has been removed at 200°C for 30 minutes. was determined using the Karl Fischer method.

The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples unless it departs from the gist of the present invention. Throughout this specification, all temperatures are in degrees Celsius, and parts and percentages are by weight unless otherwise specified.

[0033]

【Example】

Production Example 1 Production of Allyl Ester Resin (1) A 1-liter reactor equipped with a distillation apparatus was charged with 600 g (2.44 mol) of diallyl terephthalate, 95.9 g (1.26 mol) of propylene glycol, and 0.1 g of dibutyltin oxide. The mixture was heated to 180° C. under a nitrogen stream, and the allyl alcohol produced was distilled off. When 140 g (2.41 mol) of allyl alcohol was distilled out,
The pressure inside the reactor was reduced to 50 mmHg to accelerate the distillation rate. After allyl alcohol equivalent to propylene glycol was distilled off, unreacted diallyl terephthalate was distilled off at 1 mmHg while maintaining the reaction solution at 200° C. using a thin film distiller. The reaction solution was poured into a vat, cooled and pulverized to obtain powdered allyl ester resin (1).

Production Example 2 Production of Bromine-Containing Allyl Ester Resin (2) Allyl Ester Resin (1) except for the conditions shown in Table 1.
In the same manner as above, a bromine-containing allyl ester resin (2) was obtained.

[0035]

[Table 1]

In Table 1, "DATP" stands for diallyl terephthalate, "DBNPG" stands for dibromneopentyl glycol, and "halogen content" means the halogen content in the product resin.

Example 1 Melamine resin (Nicaregin S-30 manufactured by Nippon Carbide Co., Ltd.)
5) in a 50% aqueous methanol solution to give a solid content concentration of 1.
A 5% solution was prepared. This solution has a basis weight of 155 g/m2,
After soaking 300 μm thick kraft paper, it was squeezed with a roller and dried at 120° C. for 30 minutes. The obtained paper base material contains 15 parts by weight of melamine resin based on 100 parts by weight of the paper base material before treatment.
Part by weight was attached. This paper base material was floated in a blended solution of the resin composition shown in Table 2, and one side was impregnated with the resin liquid, seven sheets were stacked, and one side was coated with adhesive-coated copper foil (MK-61, manufactured by Mitsui Mining & Mining Co., Ltd.). Copper foils (basis weight 300 g/m2) were stacked one on top of the other, a 50 μm polyester film was placed on both sides, and heat and pressure molding was performed using a press machine.

[0038] Heating and pressing conditions were 150°C, 5 minutes, and 30 kg.
/cm2. After pressing, 180℃ in a hot air drying oven.
Heating was performed at ℃ for 1 hour. Furthermore, as a result of being left in a constant temperature and humidity chamber at a temperature of 50°C and a relative humidity of 90% for 8 hours, the thickness of
．． A 6 mm copper foil-clad laminate was obtained. When the moisture content of the copper foil-clad laminate was measured, it was 2.0% based on the laminate with the copper foil removed. Table 3 shows the test results of the copper foil clad laminate.
- Shown in Table 4.

Examples 2 and 3 and Comparative Examples 1 and 2 Copper foil-clad laminates were obtained in the same manner as in Example 1, except that the time of standing in the constant temperature and humidity chamber was changed. The moisture content and test results of the copper foil-clad laminate are shown in Tables 3 and 4.

[0040]

[Table 2]

[0041]

[Table 3]

[0042]

[Table 4]

In Table 3, "water content" and "resin content" are both expressed based on the laminate from which the copper foil has been removed. In addition, the tests for "bending strength", "soldering heat resistance" and "insulation resistance" are all conducted according to JIS-C-
It was carried out according to 6481.

As is clear from the results of the Examples and Comparative Examples in Tables 3 and 4, the moisture content of the laminates from which the metal foil has been removed is within the range of 0.1 to 5.0% by weight. The laminate is
It can be seen that both punching workability and bending strength are excellent.

[0045]

As explained above, according to the present invention, it is possible to obtain an allyl ester resin-based electrical laminate having high mechanical strength and excellent punching workability and electrical properties.

Claims (1)

[Claims] [Claim 1] A base material mainly composed of cellulose fibers,
In electrical laminates made of allyl ester resin and metal foil, the moisture content of the laminate from which the metal foil has been removed is 0.
．． An electrical laminate characterized in that the content is in the range of 1 to 5.0% by weight.