JPS5935849B2 - Method for manufacturing heat-resistant laminate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a heat-resistant laminate suitable for use, for example, in heat-resistant electrical insulators.

More specifically, we manufacture heat-resistant laminates with excellent heat resistance, nonflammability, water resistance, and mechanical strength by heat-pressing molding of multiple base materials using a binder containing boric acid and zinc oxide as essential components. Regarding the method. Conventionally, heat-resistant laminates have been formed using glass fiber cloth or asbestos as a base material, using boric acid and zinc oxide as binders, and heating and pressurizing them. In the conventional manufacturing method, first, a mixture of orthoboric acid and zinc oxide powder as a binder is uniformly laminated on a base material such as glass fiber cloth or asbestos board, and the mixture is heated at 130 to 200 °C. at temperatures ranging from 100 to 3
The base materials were bonded by heating and pressing at a pressure of 9/cTil. In the above-mentioned conventional manufacturing method, boric acid is used as a component of the binder, so foaming occurs due to dehydration of the boric acid, and the binder protrudes during hot-pressure molding, creating pores inside the insulator. Easy to do. Alternatively, when molding a thick material, there are drawbacks such as difficulty in raising the temperature at the center due to heat absorption due to dehydration reaction, which complicates manufacturing conditions. In order to compensate for the above drawbacks, there is a method of using metaboric acid or boric anhydride instead of orthoboric acid, but the orthorhombic form of metaboric acid (metaboric acid ■) quickly reverts to orthoboric acid in the air at room temperature. The monoclinic crystal form (metaboric acid ■) reverts to orthoboric acid by long-term storage in the air at room temperature, and the equiaxed crystal form (metaboric acid I) is relatively stable, but it is expensive. The disadvantage is that it is high.

Although boric anhydride is generally amorphous, it reverts to orthoboric acid when stored in the atmosphere at room temperature for a long period of time. As described above, metaboric acid or boric anhydride is often mixed with orthoboric acid in the atmosphere at room temperature, making it impossible to achieve the intended purpose. Furthermore, in order to compensate for the above-mentioned drawbacks, conventional methods have often adopted complicated methods such as removing pressure and removing water vapor during heating and pressurization.

The present invention overcomes the above-mentioned drawbacks and provides a new manufacturing method for easily manufacturing a heat-resistant laminate.

In the present invention, a base material made of a thin inorganic material is laminated with a binder containing orthoboric acid and zinc oxide as essential components, which is heated at 100 to 130 °C, and then heated to 50 to 30 °C.
The present invention relates to a method for producing a heat-resistant laminate, which is characterized by heating at a temperature of 175°C to 220°C under a pressure of 0 kg/Cd.

The method of the present invention was completed as a result of detailed investigation of the decomposition process and melting process of orthoboric acid.

As a result of investigating the decomposition and melting process of orthoboric acid using a differential thermal analyzer, a gravimetric thermal analyzer, a high-temperature X-ray diffractometer, etc.
It turns out that the process is as follows. That is, when heated gradually, H3BO3 (orthoboric acid) includes the process of rapidly heating orthoboric acid at the initial stage of heating and pressurization. Dehydration of orthoboric acid occurred simultaneously with melting, which caused foaming and heat absorption. When heated gradually,
The dehydration and transformation processes take place in stages, and melting or softening phenomena do not occur until temperatures exceed 280°C. On the other hand, when examining the melting points of orthoboric acid, metaboric acid (orthorhombic form), and metaboric acid (monoclinic form), the melting points were 171°C and 176°C, respectively.
℃, 201℃. The present invention makes good use of stepwise changes caused by gradual heating and melting of metaboric acid to bond substrates. At this time, since boric acid alone cannot provide water resistance, zinc oxide is added. In addition, the results of measurements such as differential thermal analysis when zinc oxide was added showed that orthoboric acid underwent the process described above even when 70% by weight of zinc oxide was added. According to the method of the present invention, first, a mixed powder of orthoboric acid and zinc oxide as a binder is prepared.

The mixing ratio of each component is preferably within the range of 20 to 70 parts by weight of zinc oxide to 80 to 30 parts by weight of orthoboric acid. Orthoboric acid is 8
If the amount exceeds 0 parts (parts by weight, the same applies hereinafter), the water resistance of the resulting laminate will be significantly impaired, and if the amount of orthoboric acid is less than 30 parts, the hot-press molding properties will be significantly impaired. Furthermore, even if other inorganic substances such as calcium oxide alumina, magnesia, silica sand, zircon, mullite mica, spodumene, and petalite oxides or complex oxides such as silicates are added to the above compound, the manufacturing method will not change. There isn't. Next, prepare the base material.

As the base material, a thin sheet material made of inorganic fiber such as glass fiber, asbestos, rock wool, ceramic fiber, etc. is used. The above-mentioned binding material is dispersed and arranged on the above-mentioned base material. Note that when dispersing and arranging, for example, a method such as scattering a powdery binder is used. The amount of the above binding material is 20 to 7
5 parts to 70 to 25 parts of the binder.

If the base material is less than 20 parts, the resulting laminate will not have sufficient mechanical strength, and if the base material is more than 75 parts, the binding effect of the binder will not be sufficient, and the resulting laminate will have low mechanical strength. Become. The bonding material arranged and laminated as described above is first heated at a temperature of 100°C to 130°C.
Usually heated for 30 minutes to 3 hours (generally the lower the temperature, the longer the heating time), then 175°C to 220°C.
In this step, heating and pressing are performed under a pressure of 50 to 300 kg/(V7I) for usually 15 to 30 minutes to form the product.

If the molding temperature is below 175°C, molding is difficult, and if it exceeds 220°C, defoaming becomes rapid and the number of bubbles increases. In addition, if the molding pressure does not reach 50 kg/Cd, the binding force will not be sufficient, and if it exceeds 300 kg/Cd, the base material will be more likely to break and the strength of the resulting molded product will decrease, which is undesirable. . Furthermore, if necessary,
There is no problem in performing a reheat treatment at 180°C to 200°C after the above-mentioned pressure and heating. The manufacturing method of the present invention will be explained below using Examples.

Example 1 Glass fiber nonwoven fabric (commercially available 300k9/r!
A powder mixture of 50% by weight of orthoboric acid and 50% by weight of zinc oxide was added to
A laminate was obtained by dispersing 6 sheets of the nonwoven fabric (bonding material) at a ratio of glass fibers and binding material of 67:33, and placing one sheet of the above-mentioned nonwoven fabric on top.

After heating it in an oven at 120℃ for 2 hours,
Before the temperature drops below 0℃, quickly place it on a hot iron plate heated to 180℃ and get 100k9/Cfi! 15 at L pressure
Heat and pressure molding was performed for minutes. In this way, the thickness is 1
．． 6mm, width 250m7n. A molded article with a length of 250 mm was obtained. Example 2 Powder mixture of 70% by weight of orthoboric acid and 30% by weight of zinc oxide (
A laminate was obtained in exactly the same manner as in Example 1, except that a bonding material) was used.

Heat it in an oven at 120°C for 2.5 hours, take it out, and before the temperature drops below 70°C, place it on an iron plate heated to 18°C and heat and press it for 30 minutes at a pressure of 150kg/(V7f). In this way, the thickness was reduced to 1.
A molded product measuring 6 m long, 250 mm wide, and 250 mm long was obtained. Example 3 A powder mixture (binding material) consisting of 80% by weight of orthoboric acid and 20% by weight of zinc oxide was used, and the ratio of the base material to the binding material was 50:5.
A laminate was obtained in the same manner as in Example 1, except that the number of particles was 0.

Next, this laminate was heated in an oven at 130°C for 2 hours, and taken out and heated to 180°C before it reached 70°C.
Place it on a hot iron plate and heat it at a pressure of 150k9/Cd.
Heat and pressure molding was performed for 5 minutes. In this way, a laminate with a thickness of 1.5 mm, a width of 250 mm, and a length of 250 mm was obtained. Example 4 A powder mixture (binding material) consisting of 40% by weight of orthoboric acid and 60% by weight of zinc oxide was used, and the ratio of the base material to the binding material was 50:5.
A laminate was obtained in the same manner as in Example 1, except that the number of particles was 0.

Next, this laminate was heated in an oven at 110°C for 3 hours, and taken out and heated to 200°C before it reached 70°C.
Place it on a hot iron plate and heat it at a pressure of 100k9/Cd
Heat and pressure molding was performed for 5 minutes. In this way, a laminate having a thickness of 1.7 m771, a width of 250 mm, and a length of 250 m7 was obtained. Example 5 Powder mixture of 50% by weight of orthoboric acid and 50% by weight of zinc oxide (
binder), and the ratio of glass fiber and binder was 60:40.
A laminate was obtained in the same manner as in Example 1 except for the following.

This laminate was then placed in an oven at 120°C for 3 hours.
Heat it for an hour and take it out before it reaches 70℃.
It was placed on an iron plate heated to 0° C. and heated and pressed for 15 minutes at a pressure of 200 k9/cm. In this way, a product having a thickness of 1.9 mm, a width of 250 mwL, and a length of 250 mm was obtained. Example 6 Glass fiber nonwoven fabric (commercially available 300 kg/Cd
(cut into 500 x 500 pieces) and orthoboric acid
Powder mixture of 0% by weight and 30% by weight of zinc oxide (binder)
A laminate was obtained in the same manner as in the above example except that the weight ratio of glass fiber and binding material was 60:40.

Next, heat this laminate in an oven at 120°C for 1 hour, and quickly raise the temperature to 180°C before the temperature drops below 70°C.
15 at a pressure of 100k9/Cd on an iron plate heated to
Heat and press for 27 nm in thickness, 500 m in width, and 50 m in length.
A laminated molded plate of 0.07 ngL was obtained. Example 7 The laminated molded plate obtained in Example 1 was heated at 180°C for 10
heated for an hour.

Table 1 summarizes the properties and blending ratios measured for the heat-resistant laminate obtained as described above.

All of the heat-resistant laminates obtained as described above have excellent mechanical strength, electrical insulation properties, and machinability, and are suitable for use as electrical insulating materials in areas that require heat resistance, for example. It was hot.

In the above embodiments, a non-woven glass fiber fabric was used, but it may be a woven fabric, a crystallized glass fiber, or a base material made of the other inorganic fibers mentioned above. Even so, the effect remains the same.

Claims (1)

[Claims] 1. A base material made of thin inorganic material and a binder containing orthoboric acid and zinc oxide as essential components arranged and laminated, heated at 100°C to 130°C, and then heated to 50 to 300 k
A method for producing a heat-resistant laminate, which comprises heating at a temperature of 175°C to 220°C under a pressure of g/cm^2. 2 80-30 parts by weight of orthoboric acid, 20-7 parts by weight of zinc oxide
The method for producing a heat-resistant laminate according to claim 1, characterized in that 0 parts by weight is used. 3. The method for producing a heat-resistant laminate according to claim 1 or 2, wherein the heating time is 30 minutes to 3 hours when heating at 100°C to 130°C. 4. Any one of claims 1 to 3, characterized in that when heating under a pressure of 50 to 300 kg/cm^2, the pressure heating time is 15 to 30 minutes. A method for producing the heat-resistant laminate described above.