JPH0341599B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to primary treated paper for electrical insulating laminates, particularly primary treated paper for paper-based synthetic resin electrical insulating laminates that has excellent dimensional stability, punching workability, electrical properties, and heat resistance. This relates to a manufacturing method. [Prior art] Laminate base paper 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 then dried, heated and formed into electrically insulating laminates. , are mainly used as printed wiring boards 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 conditions for using 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 demand for laminate base paper that has good dimensional stability for electrically insulating laminates, low-temperature punching workability, electrical properties, heat resistance, etc. Conventionally, bleached kraft pulp paper has been used as a base paper for laminate boards made from wood pulp, and although it has good dimensional stability, it has poor low-temperature punching processability and is problematic as a base paper for laminate boards for high-density wiring. Ta. In addition, Kotton linter paper made from Kotton linter, a non-wood pulp, has better punching workability, electrical properties, and heat resistance than bleached kraft pulp paper, but it also has poor dimensional stability. It is not suitable as a base paper for laminate boards for high-density wiring. As base paper for laminated boards for high-density wiring, base papers that have the dimensional stability of bleached kraft pulp paper and the low-temperature punching processability, electrical properties and heat resistance of cotton linter paper, or those with higher performance in terms of dimensional stability, are recommended. The appearance of the original paper is awaited. On the other hand, on the synthetic resin side for electrically insulating laminates, studies have been conducted to meet the above-mentioned quality requirements by modifying resins and adding additives, but no satisfactory results have yet been obtained. The current situation is that this is not the case. JP-A No. 61-296199, JP-A-Sho
No. 61-293231 discloses a method that can satisfy the above requirements, but its dimensional stability is comparable to conventional bleached kraft pulp paper. [Problems to be Solved by the Invention] The present invention has excellent low-temperature punching workability, electrical properties, and heat resistance required for high-density wiring electrical insulating laminates, and has particularly excellent dimensional stability. The present invention provides a primary treated paper for electrically insulating laminates. [Means for Solving the Problems] As a result of intensive studies to solve the above-mentioned problems, the present invention has been developed by applying and drying a water-soluble thermosetting synthetic resin to base paper for laminates. In the manufacturing process of primary treated 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, the purpose is to We have discovered that this can be achieved. Note that the term "applied paper" as used herein refers to the paper immediately after the application of the water-soluble thermosetting synthetic resin for primary treatment (before drying), and the paper after the application has been further dried is defined as the primary treated 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 are no particular restrictions 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 use a relatively light water content of 450 ml or more. Preferably, it is a beaten product. There are no particular restrictions on the basis weight or density of the base paper for laminates, but considering workability and productivity when processing into laminates, the basis weight should be 60 to 280 g/m ² ,
A density of about 0.4 to 0.7 g/m ³ is suitable. As the water-soluble thermosetting synthetic resin for primary treatment to be applied to the laminate base paper, a water-soluble thermosetting synthetic resin having a relatively low degree of polymerization can be used. Typical examples include, but are not limited to, phenolic resins, epoxy resins, and melamine resins. As the water-soluble phenolic resin, a resol type phenolic resin or a phenolic resin derivative can be used. As a water-soluble epoxy resin, patent application No. 61-296199
Mono(or poly)alkylene glycol polyglycidyl ethers, mono(or poly)alkylene glycol monoglycidyl ethers represented by those described in No. 1, and the like can be used alone or in combination. Examples of the water-soluble epoxy resin catalyst include sodium hydroxide, potassium hydroxide, zinc borofluoride, magnesium borofluoride, tin chloride, quaternary ammonium salt,
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, Cydianamide and the like can be used. As the water-soluble melamine resin, various methylolated products and derivatives such as methylolated products partially converted into alkyl ethers can be used. The water-soluble thermosetting synthetic resin for primary treatment may contain fillers,
Pigments, dyes, plasticizers, flame retardants, etc. can also be blended as appropriate. The solvent may be water alone or a mixture of water and an organic solvent such as an alcohol. The ratio of water-soluble thermosetting synthetic resin for primary treatment in the primary treatment paper for electrical insulation laminates is 1 to 20%.
The amount of volatile matter during the primary treatment is 1 to 15%.
degree is suitable. Conventionally, the method of applying water-soluble thermosetting synthetic resin for primary treatment to the base paper for laminates is to apply it to the base paper for laminates using various impregnating heads in the state of water or a mixed solution of water/organic solvent, and then apply it horizontally or vertically. This type is dried using hot air drying equipment. 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 impregnate the primary treated paper for electrical insulating laminates to make prepregs. be. The primary treated 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%. If necessary, fillers, pigments, dyes, plasticizers, flame retardants, etc. can be added to the synthetic resin. 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] By using a primary treated paper for electrical insulating laminates in which a water-soluble thermosetting synthetic resin is applied and contained in the form of an aqueous solution to the laminate base paper and then heated and dried,
It is possible to improve low-temperature punching workability, electrical properties, and heat resistance while maintaining good dimensional stability in electrical insulating laminates (Japanese Patent Application No. 61-296199, Patent Application No. 61-
No. 293231). This means that water-soluble thermosetting synthetic resins with active groups such as methylol groups and epoxy groups are applied to the base paper in the form of an aqueous solution and then heated and dried. This is thought to be the result of the presence of the curable synthetic resin, which improves the affinity (adhesion) with the synthetic resin that is impregnated later and promotes the integration of the base paper and the synthetic resin as a composite material. In the manufacturing process of primary treated paper for electrical insulating laminates obtained by applying a water-soluble thermosetting synthetic resin, the present inventors have developed a method for drying by suppressing shrinkage in the direction perpendicular to the running direction of the applied paper. It has been found that by using the primary treated paper obtained by this method, the dimensional stability of electrically insulating laminates can be further significantly improved while maintaining good electrical properties and low-temperature punching workability. This is thought to be because the paper coated with a water-soluble thermosetting synthetic resin was tension-dried to increase its internal stress, resulting in a smaller 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 A commercially available resol type water-soluble phenolic resin, trade name J-303 (manufactured by Dainippon Ink & Chemicals Co., Ltd.), is dissolved in water to prepare a treatment liquid. The treatment liquid has a basis weight of 135
g/m ² of bleached kraft pulp paper on a paper machine and heated and dried with a Yankee dryer to obtain primary treated paper with a water-soluble phenolic resin addition rate of ★1 10% and volatile content of ★2 5%. . This primary treated paper is coated with a commercially available alcohol-soluble tung oil-modified phenolic resin [trade name BLS-3122: manufactured by Showa Kobunshi Co., Ltd.]
was impregnated and dried to produce prepreg. Next, 8 sheets of prepreg and 1 sheet of copper foil with adhesive (thickness: 35 μm) were laminated and hot-press molded at 155℃, 100Kg/cm ² for 60 minutes, and cooled for 30 minutes while still under pressure. A single-sided copper-clad electrical insulating laminate with a resin impregnation rate of ★3 50% and a thickness of 1.6 mm was obtained. ★1 Application rate = B-A/B x 100% ★2 Volatile Content = B-C/B x 100% ★3 Resin impregnation rate = D-nA/D x 100% A: Untreated base paper weight (g/m ² ) B: Weight of primary treated paper coated with water-soluble thermosetting synthetic resin (g/m ² ) C: Weight of primary treated paper after heating at 150°C for 10 minutes (g/m ² ) D: Electricity Weight of insulating laminate (g/m ² ) n: Number of layers of laminate base paper per electrical insulating laminate Example 2 The treatment solution used in Example 1 was applied to bleached kraft pulp paper with a basis weight of 135 g/m ² A single-sided copper-clad electrical insulating laminate with a resin content of 50% and a thickness of 1.6 mm was prepared in the same manner as in Example 1. I got it. Example 3 The treatment solution used in Example 1 was applied to bleached kraft pulp paper with a basis weight of 135 g/m ² using a conventional impregnating head, and then heated and dried using a multi-cylindrical cylinder using a conventional canvas. Example 1
In the same manner as above, a single-sided copper-clad electrical insulating laminate with a resin content of 50% and a thickness of 1.6 mm was obtained. Example 4 100 parts by weight of ethylene glycol diglycidyl ether, which is a water-soluble epoxy resin, and 1 part by weight of zinc borofluoride as a catalyst are dissolved in water to prepare a treatment liquid. This treatment liquid is applied to cotton linter paper with a basis weight of 135 g/m ² on a paper machine and heated and dried with a Yankee dryer to produce primary treated paper with a water-soluble epoxy resin applied with an application rate of 8% and a volatile content of 3%. After obtaining, the resin content was determined in the same manner as in Example 1.
A single-sided copper-clad electrical insulating laminate with a thickness of 1.6 mm and a thickness of 1.6 mm was obtained. Example 5 Trimethylolmelamine, which is a water-soluble melamine resin, is dissolved in water to prepare a treatment liquid. This treatment solution was applied to bleached kraft pulp paper with a basis weight of 135 g/m ² on a paper machine, and then heated and dried in a multi-tubular cylinder using a conventional canvas. After obtaining the primary treated paper coated with a melamine resin, the procedure was repeated in the same manner as in Example 1 to obtain a single-sided copper-clad electrical insulating laminate with a resin content of 50% and a thickness of 1.6 mm. Comparative Example 1 The treatment solution used in Example 1 was applied to bleached kraft pulp paper with a basis weight of 135 g/m ² using an impregnation machine (coater), and the process was the same as in Example 1. 50% resin content, plate thickness
A 1.6 mm single-sided copper-clad electrical insulating laminate 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 impregnation machine, and the resin was dried by heating 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. Comparative Example 3 A resin was prepared in the same manner as in Example 5, except that the treatment liquid used in Example 5 was applied to bleached kraft pulp paper with a basis weight of 135 g/m ² using an impregnation machine, and the resin was dried by heating 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 results of the above examples and comparative examples are 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 paper to which the water-soluble thermosetting synthetic resin is applied by the drying method of the present invention is determined by the tension in the direction perpendicular to the running direction.
Since the applied paper is dried with suppressed shrinkage in the orthogonal direction, the elongation in water is smaller and the Young's modulus is higher than that of the paper dried by the normal hot air drying method. In addition, the quality of the electrically insulating laminate remains good in electrical properties and punching workability, and it has even better dimensional stability (warpage) than those dried by the hot air drying method. Therefore, the industrial significance of the primary treated 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 paper for electrically insulating laminates obtained by applying a water-soluble thermosetting synthetic resin to base paper for laminates and drying it, a process that runs perpendicular to the running direction of the coated paper A method for producing primary treated paper for electrical insulating laminates, which is characterized by drying while suppressing directional shrinkage. 2. The method for producing a primary treated paper for electrically insulating laminates according to claim 1, wherein the water-soluble thermosetting synthetic resin is a phenolic resin. 3. The method for producing a primary treated paper for electrical insulation laminates according to claim 1, wherein the water-soluble thermosetting synthetic resin is an epoxy resin. 4. The method for producing a primary treated paper for electrically insulating laminates according to claim 1, wherein the water-soluble thermosetting synthetic resin is a melamine resin.