JPS621664B2 - - Google Patents

Description

[Detailed description of the invention]

Mica boards using conventional inorganic binders are
Compared to mica boards made with organic binders, they are inferior in moisture resistance, bending strength, and punching properties, in addition to heat resistance, and are also brittle, which is unique to inorganic materials.Flake mica base materials are used to compensate for this. . In addition, mica boards using boric acid binders require higher temperature pressing than mica boards using organic binders, are more expensive in terms of equipment, and require a large amount of operating expenses. It becomes expensive. On the other hand, when using a binder whose main component is phosphoric acid, there is no need for high-temperature pressing as mentioned above and the manufacturing process is simple, but since the binder itself is hygroscopic, the resulting mica plate also becomes electrically insulating due to moisture absorption. sex is significantly reduced. In particular, when a composite mica is used as a base material, the mechanical strength of the mica plate is low, it is brittle, and its punchability is poor because the binder is not a polymer. The present invention provides an inorganic binder that improves the mechanical strength, punchability, brittleness, moisture resistance, etc. of conventional mica plates. The present invention provides P ₂ O ₅ in relative mol% of 20.49 to 22.82,
Na ₂ O from 31.81 to 40.16, A ₂ O ₃ from 0 to 4.56 and
This invention relates to an inorganic binder containing B ₂ O ₃ in a range of 39.35 to 40.80, with a total content of 100. The above inorganic binders include phosphoric acid, sodium phosphate, aluminum phosphate, caustic soda,
It is obtained by blending soda carbonate, boric acid, sodium borate, etc. in predetermined amounts. When each of the above components is outside the above range, the resulting inorganic binder becomes unstable, becomes cloudy, and tends to have poor moisture resistance. The inorganic binder of the present invention is applied to a mica plate or the like by a conventional method. A mica plate obtained by dissolving or suspending the above-mentioned inorganic binder in water and impregnating it into a composite mica sheet or mica powder, drying it, and then heating and pressing it has excellent moisture resistance and mechanical strength. Examples of the present invention will be described. Example 1 1 53 g of anhydrous sodium carbonate (Na ₂ CO ₃ ) was added to 131 g of 75% orthophosphoric acid (H ₃ PO ₄ ), and then 184 g of water was added.
was added and dissolved. Then sodium tetraborate
184 g of decahydrate (Na ₂ B ₄ O ₇ .10H ₂ O) was added and dissolved to form an inorganic binder. The obtained inorganic binder contained 20.49 mol%
_{P2O5 ,} 40.16 mol% _Na2O and 39.35 mol%
of B ₂ O ₃ . 2 Laminated mica sheet (pulp mica manufactured by Hitachi Chemical Co., Ltd., thickness 0.08 mm 500 x 1000 mm) approximately 70 g
The above-mentioned inorganic binder was spray coated on the mica sheet so that the binder amount was 8% by weight, and then dried at 105° C. for 30 minutes to obtain a mica sheet. 3 Layer 20 mica sheets created in 2,
Heat and pressure treatment was carried out at 190±5° C. and a pressure of 60 Kgf/cm ² for about 2 hours to obtain a mica plate with a thickness of 1 mm. 4 Place the mica board obtained in step 3 in the dryer in an open state.
The temperature is raised from 90℃ to 200℃ over about 6 hours and then heated to 200℃.
It was treated for 4 hours. Furthermore, the mica plate was placed in an electric furnace and heated from 200℃ to 650℃ over about 8 hours.
Heat treatment was performed at 650°C for 3 hours to obtain a heat-resistant mica board. Example 2 1 20 mica sheets prepared in Example 1-2 were laminated and subjected to heating and pressure treatment at 380±10° C. and a pressure of 100 Kgf/cm ² for about 1 hour to obtain a mica plate of about 1 mm. 2. The mica plate obtained in 1 was placed in an open oven at 200°C and treated for 3 hours. Furthermore, the mica board was transferred to an electric furnace, and the temperature was raised from 200°C to 650°C over about 8 hours, and then heat-treated at 650°C for 3 hours to obtain a heat-resistant mica board. Example 3 1 78.0 g of sodium dihydrogen phosphate (NaH ₂ PO ₄ .2H ₂ O) was added to 65.3 g of 75% orthophosphoric acid (H ₃ PO ₄ ), and 186 g of water was further added and dissolved, followed by hydroxylation. 13.0 g of aluminum (A(OH) ₃ ) was added and dissolved. Next, 170.5 g of sodium tetraborate decahydrate (Na ₂ B ₄ O ₇ .10H ₂ O) was added to form an inorganic binder. The obtained inorganic binder contained 22.82 mol%
P ₂ O ₅ , 31.81 mol% Na ₂ O, 4.56 mol% A
₂ O ₃ and 40.80 mol% B ₂ O ₃ . 2 Approximately 70g of laminated mica sheet used in Example 1
Then, the above-mentioned inorganic binder was spray-coated to the mica sheet so that the binder amount was 8% by weight, and then dried at 105° C. for 60 minutes to obtain the mica sheet. 3 Layer 20 mica sheets created in 2,
Heat and pressure treatment was carried out at 380±10° C. and a pressure of 100 Kgf/cm ² for about 1 hour to obtain a mica plate with a thickness of about 1 mm. 4 Place the mica plate obtained in step 3 in an open dryer and raise the temperature from room temperature to 200℃ over about 6 hours.
It was treated at ℃ for 3 hours. Furthermore, the mica plate was transferred to an electric furnace and heated from 200℃ to 650℃ over about 8 hours.
A heat-resistant mica board was obtained by processing at 650°C for 3 hours. Table 1 shows an example of the characteristics of the heat-resistant mica board obtained in the example.

【table】

[Table] By using the inorganic binder of the present invention, a heat-resistant mica board having excellent bending strength, moisture resistance, etc. can be obtained.

Claims (1)

[Claims] 1 _P2O5 in relative mol% _20.49-22.82 , _Na2O
31.81 _{~ 40.16} , _A2O3 from 0~4.56 and _B2O3
An inorganic binder containing 100 in the range of 39.35 to 40.80.