JPH0565638B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to primary treated base paper for electrical insulating laminates, particularly primary treated base paper for paper-based synthetic resin electrical insulating laminates having excellent dimensional stability, punching workability, electrical properties, and heat resistance. This relates to a manufacturing method. [Conventional technology] The base paper for laminates is impregnated with synthetic resin varnish such as phenolic resin by a laminate manufacturer using an impregnating machine equipped with a horizontal or vertical hot air drying device, and dried, then heated and formed into electrically insulating laminates. It is mainly used as a printed wiring board in a wide range of fields such as consumer and industrial electronic equipment, but in recent years, as electronic equipment has become smaller, lighter, and more sophisticated, the usage conditions of printed wiring boards have changed. There is a growing tendency for the physical properties required of base paper for laminates to become more sophisticated. In particular, in order to cope with high-density wiring, there is a need for a base paper for laminates that has good dimensional stability for electrically insulating laminates, low-temperature punching workability, electrical properties, heat resistance, etc. Bleached kraft pulp paper has traditionally been used as a base paper for laminates made from wood pulp, and although it has excellent dimensional stability, it has poor low-temperature punching processability and is problematic as a base paper for high-density wiring laminates. Ta. In addition, Kotton linter paper, which is made from non-wood pulp, has better punching workability, heat resistance, and electrical properties than bleached kraft pulp paper, but its dimensional stability is inferior, so it is also used as a base paper for high-density wiring laminates. is not suitable. The emergence of a base paper for high-density wiring laminates that combines the dimensional stability of bleached kraft pulp paper with the low-temperature punching processability, heat resistance, and electrical properties of cotton linter paper is awaited. On the other hand, on the side of synthetic resins for laminates, studies have been conducted to meet the above-mentioned quality requirements by modifying resins, adding additives, etc., but satisfactory results have not yet been obtained. is the current situation. JP-A-61-
296199 and JP-A-61-293231 disclose a method that can satisfy the above requirements, but the dimensional stability is at the same level as conventional bleached kraft pulp paper. [Problems to be Solved by the Invention] The present invention provides an electrical insulating laminate that has good low-temperature punching workability, heat resistance, and electrical properties required for high-density wiring boards, and has particularly excellent dimensional stability. It provides primary treated base paper. [Means for Solving the Problems] As a result of intensive studies to solve the above-mentioned problems, the present invention provides an electrically insulating laminate obtained by applying a self-emulsifying epoxy resin to a base paper for a laminate and drying it. This objective can be achieved by using a primary treated base paper for electrical insulating laminates, which is characterized by suppressing shrinkage in the direction perpendicular to the running direction of the coated paper and drying in the manufacturing process of the primary treated base paper for boards. This is what I discovered. Note that the coated paper referred to herein refers to the paper that has just been coated with the self-emulsifying epoxy resin for primary treatment (before drying), and the coated paper that has been further dried is defined as the primary treated base paper. The present invention will be explained in more detail. Commercially available base paper for laminated boards can be used as the base paper for laminated boards, but it has the same amount of contaminants as bleached kraft pulp paper.
If it has water immersion liquid conductivity, the material pulp type,
There are no particular restrictions on the cooking method, bleaching method, etc. There is no particular restriction on the pulp water content when making the base paper for laminates used in the present invention, but in order to improve the permeability of the resin into the base paper for laminates, it is necessary to set it at 450 ml CSF or more. It is preferable that it be relatively lightly beaten. There are no particular restrictions on the basis weight or density of the base paper for laminated boards, but considering workability and productivity when chemically processing them into laminated boards, the basis weight should be 60 to 280 g/ ^m2 ,
A density of about 0.4 to 0.7 g/m ³ is suitable. As the self-emulsifying epoxy resin for primary treatment applied to the base paper for laminates, polyalkylene glycol-modified bisphenol A-type glycidyl ether can be used. Bisphenol A type glycidyl ether is originally a solvent-based epoxy resin and does not self-disperse in water. However, this type of epoxy resin is a self-emulsifying epoxy resin modified into a water-dispersible emulsion type by introducing polyalkylene glycol into the side chain of the bisphenol A main chain. Catalysts for self-emulsifying epoxy resins include sodium hydroxide, potassium hydroxide, zinc borofluoride, magnesium borofluoride, tin chloride (), quaternary ammonium salts, tertiary amines, imidazole compounds, boron trifluoride, etc. can be used. In addition, as curing agents, amines such as aliphatic polyamines, aromatic polyamines, secondary and tertiary amines, acid anhydrides such as phthalic anhydride, synthetic resin initial condensates such as phenolic resins and melamine resins, other polyamide resins, Dicyandiamide and the like can be used. The solvent may be water alone or a mixture of water and an organic solvent such as an alcohol. Furthermore, in order to promote the dispersion of the self-emulsifying epoxy resin in water, a surfactant can be used in combination with the resin in an amount of up to 10%. The ratio of self-emulsifying epoxy resin in the primary treated base paper for electrically insulating laminates is preferably 1 to 20%. Conventionally, the method of applying self-emulsifying epoxy resin for primary treatment to the base paper for laminates is to apply it to the base paper for laminates in the form of water or a mixed solution of water/organic solvent using various impregnating heads, and then apply it to the base paper for laminates in a horizontal or vertical type. A type that dries with a hot air dryer is used. In this case, the applied paper shrinks freely in the direction perpendicular to the running direction. In the present invention, in order to suppress the shrinkage of the applied paper in the direction perpendicular to the running direction, drying is performed with tension applied also in the perpendicular direction. Practical methods include, for example, suppressing shrinkage in the direction perpendicular to the running direction by drying the coated paper in a multi-cylinder dryer or Yankee dryer using a single canvas or conventional canvas in which the paper is accompanied by a carrier. becomes possible. The application means may be on-machine (paper machine) or off-machine (impregnation machine, coater, etc.). Next, synthetic resins such as phenol resins, melamine resins, diallyl phthalate resins, epoxy resins, and unsaturated polyester resins can be used as resins for laminates to be impregnated into the primary treated base paper for electrical insulating laminates to make prepregs. be. The primary treated base paper for laminates of the present invention is impregnated with the above synthetic resin varnish to form a prepreg, which is then laminated and molded under heating to obtain an electrically insulating laminate. A known method can be used for heat forming. The resin content of the prepreg is preferably in the range of 40 to 65%. Fillers, pigments, dyes, plasticizers, flame retardants, etc. can be added to the synthetic resin as appropriate. Note that a metal foil-clad laminate can also be obtained by placing metal foil on one or both sides of the laminate made of the prepregs and performing heating lamination molding. [Function] It has already been reported that the use of polyalkylene glycol glycidyl ether (including water-soluble epoxy resins) as a modifier for phenolic resins plasticizes the resin and improves the punching processability of laminates. 1976-62916). In addition, it has already been reported that punching workability of laminates as well as dimensional stability and heat resistance can be improved by applying water-soluble epoxy resin in the form of an aqueous solution to base paper and drying it, rather than in phenolic resin. (Japanese Patent Application Laid-Open No. 61-296199). The present inventors used bisphenol A, which has high heat resistance and water resistance, instead of using epoxy resins having mono- or polyalkylene glycol as the main chain (Japanese Patent Application Laid-Open No. 61-296199).
Polyalkylene glycol-modified bisphenol A-type glycidyl ether, which is a self-emulsifying epoxy resin with a main chain of It has been found that not only heat resistance and dimensional stability can be improved, but also electronic insulation properties can be improved. This means that
A self-emulsifying epoxy resin with active epoxy groups is added to the base paper, and the epoxy resin exists not only on the fiber surface but also within the membrane or fiber wall via hydrophilic groups, so that the epoxy group and cellulose of wood fibers are This is thought to be the result of a chemical bond being formed with the hydroxyl group, which further improves the affinity with the phenolic resin that is impregnated later, and promotes the integration of the base paper and the phenolic resin as a composite material. Furthermore, since the main chain of self-emulsifying epoxy resin has better water resistance than water-soluble epoxy resin, the water resistance of the electrically insulating laminate is improved, which is thought to have contributed to the improvement of electrical properties. The present inventors have discovered that in the manufacturing process of primary treated base paper for electrical insulating laminates obtained by applying a self-emulsifying epoxy resin, it is possible to suppress shrinkage in the direction perpendicular to the running direction of the applied paper and dry it. By using the primary treated base paper obtained by
It has been found that the dimensional stability of an electrically insulating laminate can be further significantly improved while maintaining good electrical properties and low-temperature punching workability. This is thought to be because the self-emulsifying epoxy resin-applied paper was strain-dried and its internal stress was increased, resulting in a decrease in the amount of expansion and contraction in response to thermal changes. [Example] Examples of the present invention and comparative examples corresponding thereto are shown below. Example 1 Polyalkylene glycol-modified bisphenol A-type glycidyl ether, which is a self-emulsifying epoxy resin, and 100 parts (hereinafter, all parts by weight) of polyethylene glycol-modified bisphenol A-type glycidyl ether whose alkylene is ethylene were used as a catalyst. 2 parts of zinc borofluoride are dissolved in water to prepare a treatment solution. This treatment liquid is applied to bleached kraft pulp paper on a paper machine and heated and dried using a Yankee dryer to achieve an application rate*1 of 15% and a basis weight of 135g/
A primary treated base paper for laminated boards containing m ² of self-emulsifying epoxy resin was obtained. This primary treated base paper was impregnated with a commercially available alcohol-soluble tung oil-modified phenol resin [trade name: BLS-3122: manufactured by Showa Kobunshi Co., Ltd.] and dried to produce a prepreg. Next, 8 sheets of prepreg and 1 sheet of copper foil (thickness 35 μm) with adhesive were laminated.
After hot-pressing molding at 155℃, 100g/cm ² for 60 minutes, and cooling for 30 minutes under pressure, resin content *2
A single-sided copper-clad electric laminate with a thickness of 1.6 mm and a thickness of 1.6 mm was obtained. *1 Application rate = B-A/B x 100 *2 Resin content = C-nA/C x 100 A: Weight of untreated base paper (g/ ^m2 ) B: Weight of primary treated base paper coated with self-emulsifying epoxy resin ( g/m ² ) C: Weight of electrically insulating laminate (g/m ² ) n: Number of layers of base paper for laminates per electrically insulating laminate Example 2 The treatment solution used in Example 1 was bleached into a craft The resin content was 51% in the same manner as in Example 1, except that it was applied to pulp paper on a paper machine and heated and dried using a multi-tubular cylinder using a conventional canvas.
A single-sided copper-clad electrical insulating laminate with a thickness of 1.6 mm was obtained. Example 3 The treatment solution used in Example 1 was applied to bleached kraft pulp paper using a conventional impregnating head, and then the resin was treated in the same manner as in Example 1. A single-sided copper-clad electrical insulating laminate with a content of 50% and a thickness of 1.6 mm was obtained. Example 4 Using polyalkylene glycol-modified bisphenol A-type glycidyl ether, which is a self-emulsifying epoxy resin, 100 parts of polypropylene glycol-modified bisphenol A-type glycidyl ether in which alkylene is propylene and 2 parts of KOH as a catalyst were dissolved in water and treated. It was made into a liquid. 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 The treatment solution used in Example 1 was applied to bleached kraft pulp paper using an impregnation machine (coater), and the resin content was 50% in the same manner as in Example 1. A single-sided copper-clad electrical insulating laminate with a thickness of 1.6 mm was obtained. Comparative Example 2 A resin was prepared in the same manner as in Example 4, except that the treatment liquid used in Example 4 was applied to cotton linter paper with a basis weight of 135 g/m ² using an impregnating machine, and then heated and dried using a horizontal hot air dryer. A single-sided copper-clad electrical insulating laminate with a content of 50% and a thickness of 1.6 mm was obtained. The progress of the Examples and Comparative Examples above is summarized in the table. Note that MD refers to the running direction, and CD refers to the direction perpendicular to the running direction.

【table】

〔Effect of the invention〕

As is clear from the table, the quality of the primary treated base paper to which the self-emulsifying epoxy resin has been applied by the drying method of the present invention is that the shrinkage of the applied paper in the direction perpendicular to the running direction is suppressed due to the tension in the direction perpendicular to the running direction. As a result, the elongation in water is smaller and the Young's modulus is higher than those dried using the normal hot air drying method. In addition, the quality of the electrical insulating laminate remains good in electrical properties and punching workability compared to those dried using the hot air drying method, and it has even better dimensional stability (warpage).
have. Therefore, the industrial significance of the primary treated base paper for electrically insulating laminates of the present invention is extremely great.

Claims (1)

[Scope of Claims] 1. In the manufacturing process of primary treated base paper for electrical insulating laminates obtained by applying a self-emulsifying epoxy resin to base paper for laminates and drying it, A method for producing primary treated base paper for electrical insulating laminates, which is characterized by drying while suppressing shrinkage. 2. The method for producing a primary treated base paper for electrical insulating laminates according to claim 1, wherein the self-emulsifying epoxy resin is polyalkylene glycol-modified bisphenol A-type glycidyl ether. 3. The method for producing a primary treated base paper for electrical insulating laminates according to claim 1, wherein the self-emulsifying epoxy resin is polyethylene glycol-modified bisphenol A-type glycidyl ether. 4. The method for producing a primary treated base paper for electrical insulating laminates according to claim 1, wherein the self-emulsifying epoxy resin is polypropylene glycol-modified bisphenol A-type glycidyl ether.