JPS6136332A - Manufacture of collected mica having surface conductivity - Google Patents

Abstract

PURPOSE:To produce collected mica having surface conductivity, efficiently at a low cost, by treating the surface of a collected mica with a liquid synthetic resin containing fine carbon particles having specific diameter and dispersed therein, removing the solvent from the liquid, and hot-pressing the treated mica. CONSTITUTION:The surface of a collected mica manufactured by forming mica flakes of 4-400 mesh is treated with a liquid resin prepared by dispersing (A) 40-100pts.wt. of fine carbon powder having particle diameter of 5-70mu in (B) 100pts.wt. of a synthetic resin, preferably epoxy resin, silicone resin, etc., to effect the impregnation of the liquid resin between the mica flakes and to form a layer of fine carbon powder on the surface of the collected mica. The treated mica is heated at 80 deg.C to remove the solvent, and hot-pressed at 150-160 deg.C to form an electrically conductive firm carbon powder layer on the surface. A collected mica having surface conductivity can be produced by this process.

Description

[Detailed Description of the Invention] O Industrial Field of Application The present invention is a lightweight and highly rigid material that is useful as an electrostatic shielding material, a conductive heating element, or an electromagnetic shielding material, and has excellent heat resistance and dimensional stability. This invention relates to a method of manufacturing a laminated mica plate having excellent surface conductivity.

O Prior Art Conventionally, a laminated mica board, which is obtained by making a paper from mica scales and impregnating a laminated mica with an adhesive made of a synthetic resin and curing it, has been widely used as a heat-resistant electrical insulating material. Recently, the laminated mica board is lightweight, has high rigidity, has very little warpage and distortion, and has excellent dimensional stability. , new applications have been developed in fields that take advantage of its high rigidity, and furthermore, when using this material in electronic and electromagnetic equipment, the surface of the laminated mica plate is polished and a conductive paint is applied on it. It has come to be used by coating and baking.However, in this case, a laminated mica sheet metal is made, and the surface is later polished with sandpaper, and then a conductive paint is applied and heated and baked. In order to carry out this process, the number of steps increased, the manufacturing cost increased, and the adhesion between the coating film and the laminated mica board was not always sufficient.

0 Purpose of the Invention The present invention provides a method for producing a laminated mica board by forming a continuous planar conductive film in advance on the surface layer of the laminated mica obtained by paper-making mica scales. The present invention aims to provide a new method for manufacturing a mica plate assembly having conductivity on its surface.

0 Structure of the Invention In order to achieve the above object, the present inventors have conducted intensive research and found that mica scales for producing aggregated mica have a particle size of 4.
A synthetic resin-impregnated mica sheet (hereinafter referred to as a bripreg mica sheet) is produced by impregnating the laminated mica with an adhesive liquid made of synthetic resin into a laminated mica sheet with a mesh size of ~40 mesh. ), when the synthetic resin liquid is impregnated with fine carbon particles having an average particle size of 5μ to 70μ dispersed in advance, the synthetic resin liquid permeates throughout the mica scales of the aggregated mica. However,
Carbon fine particles are deposited on the surface layer.

It has been found that the deposited carbon particles are integrated and bonded to the surface layer of the aggregated mica during the heat and pressure curing process, forming a strong conductive carbon particle layer on the surface. The present invention was completed based on this knowledge.

0 Summary of the Invention The summary of the present invention is to form a composite mica surface obtained by paper-making mica scales with a particle size of 4 to 40 mesh, to a particle size of 5 μ to 7 μm.
The surface is treated with a synthetic resin liquid in which 0μ carbon fine particles are dispersed, and the synthetic resin liquid is allowed to penetrate between the mica scales.
A method for producing a laminated mica plate having an electrically conductive surface includes forming a carbon fine particle-containing resin layer on the surface, drying and removing the solvent, and applying heat and pressure.

The mica scales used in the present invention have a particle size of 4 to 40
Must be mesh. If the thickness exceeds 4, the mica scales are too large and easily settle in water, making it difficult to make the mica slurry flow uniformly, making it difficult to obtain aggregated mica with a uniform thickness.
With fine particles passing through 0.00 M/U, it is difficult to form a paper using a normal paper forming method because of leakage from the paper forming wire.

These mica scales are obtained by beating the tJR material mica with a water jet, then collecting them through a 4 to 40 mesh screen, and making them into a composite mica by using a paper machine. On the other hand, fine carbon particles having a particle size of 5 μm to 70 μm are blended in an amount of 40 to 100 parts by weight per 100 parts of synthetic resin, and mixed and dispersed in the synthetic resin liquid to prepare a liquid. As a synthetic resin,
Either thermosetting or thermoplastic resin may be used, but thermosetting resin is preferable from the viewpoint of heat resistance. Examples of suitable resins include ebogishi resin and silicone resin.

The particle size of the carbon fine particles used needs to be in the range of 5μ to 70μ. If it is less than 5μ, it will be difficult to penetrate into the inside of the aggregated mica and deposit on the surface layer, and if it exceeds 70μ, secondary aggregation will easily occur between the carbon particles, making it difficult to uniformly disperse them in the synthetic resin liquid. . The dispersion liquid is, for example,
It is produced by preparing a resin solution using solvents such as methanol, methyl ethyl ketone, and toluene, and mixing and dispersing the carbon fine particles into the resin solution.

When the dispersion liquid is sprinkled on the surface of the aggregated mica, the synthetic resin liquid penetrates between the laminated mica scales of the aggregated mica together with the solvent, and the carbon particles are deposited on the surface layer where they can pass through because they are blocked by the layer of mica scales. do.

If this is heated to 80°C to volatilize and remove the solvent, a prepreg mica sheet can be obtained. This is 150
By heating and compressing at ~160° C., a laminated mica plate having conductivity on the surface as shown in FIG. 1 is obtained. In the figure, 1 indicates mica scales, 2 indicates synthetic resin, 3Vi, and carbon fine particles.

Still, prepare the two prepreg mica sheets mentioned above,
Layer them together so that the opposite sides of the dispersion liquid spraying side are in contact with each other, and
When heated and compressed at ~160 DEG C., a laminated mica plate having electrical conductivity on both sides is obtained as shown in FIG.

Example 0 Raw material mica was crushed with a water jet, mica scales of 4 to 40 mesh were collected using an underwater screen, and the mica was formed into a paper and dried to obtain a mica of 1202 particles per 1 m to produce a composite mica. Separately, an epoxy resin liquid with the following formulation was prepared.

To this epoxy resin liquid 3002, 502 carbon fine particles (Kish graphite KNF manufactured by Motori Concentration Co., Ltd.) were added,
Mix and stir well. Take this carbon fine particle dispersed epoxy resin liquid and spray it on the surface of the 120 Y/m' aggregated mica, leave it for a while at room temperature, allow the epoxy resin to penetrate between the mica scales of the aggregated mica, and Carbon fine particles were deposited on the surface. This was placed in a constant temperature dryer at 80"C for 15 minutes, and toluene, methyl alcohol,
After volatilizing the mixed solvent of methyl ethyl ketone,
After heating and pressurizing 20 to 9/CM2 pressure for 1 hour at ~160°C, the mixture was cooled to room temperature. As a result, a laminated mica plate having a carbon fine particle layer tightly and closely bonded to the mica scales in the surface layer portion by the epoxy resin on one side of the laminated mica was obtained.

The surface resistance and volume resistivity of the obtained mica plate were measured and the results were as follows.

YHP 16008A meter manufactured by Card Co., Ltd., Y)IP 4329A manufactured by Card Co., Ltd. and TR-2112 manufactured by Takeda Riken Elastic modulus: Based on the vibration lead method.

〇Effects of the invention According to the method of the invention, conventionally, on the ice surface of the laminated mica plate,
Compared to the method of sanding the surface with sandpaper, applying a conductive paint, and baking it to give the surface conductivity, the process of impregnating the mica with resin requires
Since it is possible to form a conductive surface layer, the manufacturing process can be shortened and manufacturing costs can be lowered, and the resulting laminated mica board is lightweight and has high rigidity, as well as heat resistance and dimensional stability. The main body, which is made of mica and resin with excellent properties, and the carbon fine particle layer on the surface are strongly bonded together by heating and pressurizing, making it suitable for static electricity sealing toys, conductive heating plates, and electromagnetic shielding materials. It has excellent effects.

[Brief explanation of the drawing]

The drawings are conceptual diagrams of a cross section of a laminated mica plate obtained by the method of the present invention. Figure 1 shows a laminated mica plate having conductivity on one side, and Figure 2 shows a laminated mica sheet metal having conductivity on both surfaces. show. 1: Mica scales, 2: Synthetic resin, 32 carbon fine particles. Patent Applicant: Okabe Maikani Co., Ltd. Mtr Figure 1 Figure 3 Procedural Amendment 1985 Ir, August 27B ↑ToYl”+'Director Uga Michibe 1) 1 I゛1 Manual 1988:1- Patent Application No. 155568 2 Title of the Invention Laminated mica board with conductivity on the surface ill f
Relationship with 'l Patent applications total 14 + F 6596-1, Oaza Nakama, Nakama City, Fukuoka Prefecture
Mr ?・(Name: IA-) Maabe Maikani Office 6 Co., Ltd.
Number of inventions increased by amendment N/A 7 Subject of amendment 8 Contents of amendment □'Shellfish, lure') (1) Details F'! ' 21S Insert the following sentence after the last line of page 6. 1. Furthermore, when the surfaces coated with the dispersion and the opposite surface are placed one on top of the other and heated and compressed, an assembled mica plate having conductivity on the surface and the intermediate surface can be obtained.

Claims (1)

[Claims] The surface of aggregated mica obtained by paper-making mica scales of 1.4 to 40 mesh is surface-treated with a synthetic resin liquid in which fine carbon particles having a particle size in the range of 5 μ to 70 μ are dispersed. , After infiltrating the synthetic resin liquid between the mica scales of the assembled mica and forming a carbon fine particle layer on the surface, the solvent is removed and heat and pressure are applied to firmly bond the mica scales, synthetic resin, and carbon fine particles. 1. A method for producing a laminated mica board having a conductive surface, the method comprising: 2. The manufacturing method according to claim 1, wherein the carbon fine particle content of the carbon fine particle-containing resin liquid is 40 to 100 parts by weight based on 100 parts by weight of the resin.