JPS6020842B2 - heat resistant electrical insulation - Google Patents

Description

[Detailed description of the invention] The present invention relates to novel heat resistant electrical insulators.

Heat-resistant electrical insulators are produced by bonding insulating base materials such as mica or asbestos with a binder such as low-melting point glass, or by bonding insulating base materials such as mica or asbestos with a binder such as low-melting point glass, or by bonding a metal oxide such as alumina with a material such as silicon oxide. It was manufactured by adding a dawning accelerator as needed and firing. Among these, the so-called "micalex", in which mica powder is bound with monolead borate-based low melting glass, is widely known. This Micalex has excellent heat resistance and electrical insulation properties, but during manufacturing, it is necessary to apply pressure of about 200 to 1000 k9/m while heating it to a temperature higher than the softening temperature of the low melting point glass, that is, 500 to 800 "0. However, since the process is extremely complicated, the manufacturing cost is high. In addition to this, there is also the drawback that a reaction progresses between the mica and the glass during binding, and the mica is eroded by the glass, reducing workability. In addition to low-melting glass, phosphoric acid, phosphates such as metal primary phosphates, sols such as alumina sol and silica gel, and cement are used as binders for insulation bases. .

However, if phosphoric acid or a phosphoric acid-based binder such as phosphates is used alone, the heat resistance (400 to 50
) and electrical insulators with excellent nonflammability.
It had the disadvantage of poor water resistance and electrical properties when wet, and a chemical reaction between the insulating base material and the phosphoric acid binder, which reduced the binding effect and made it difficult to obtain uniform molded products. . Furthermore, a binder made only of phosphoric acid mixed with an organic binder made of thermosetting resin may be used as a binder, but in this case, the organic binder Decomposition may occur, making molding difficult. Furthermore, sol-based binders such as alumina sol and silica gel require high-temperature treatment at a temperature of about 1000 to 120 mm for binding, and have the same problem as Mycalex.

Furthermore, cement-based binders have the disadvantage that it is difficult to use them in combination with thermosetting resin-based binders, making it difficult to obtain delicate molded products. On the other hand, insulating porcelain made by firing metal oxides such as alumina and beryllia is primarily intended for electrical insulation under conditions such as high voltage, high frequency, and high temperature.

However, insulating porcelain made of these metal oxides has the disadvantage that it needs to be fired at a considerably high temperature during production, and it is not easy to process it into the desired shape.
In addition, it has been difficult to obtain dimensional accuracy, has low mechanical strength such as impact resistance, and is toxic, so that a fully satisfactory insulating porcelain has not been obtained. In order to solve these drawbacks, the present inventors conducted extensive research and found a fired product obtained by heating a mixture of zinc oxide and titanium oxide to a temperature of 600°C or higher, and a composition containing boric acid as an essential component. (hereinafter the composition is referred to as a binder) is bound by heat treatment under pressure, or in addition to the binder component, at least one of inorganic fibers, inorganic fillers, or thermosetting resins is added. By heat-treating and bonding a composition containing 100% under pressure, an electrical insulator with excellent mechanical properties, mechanical properties, and heat resistance that can be easily processed into a desired shape can be produced. The present invention was completed by discovering that it can be bound without requiring any treatment.

The fired product used in the present invention, which is obtained by heating the mixture of the zinc oxide source and the titanium oxide source to a temperature of 600° C. or higher, can be obtained as follows.

That is, a zinc oxide source containing zinc oxide, which produces zinc oxide by heating, preferably having a size of 100 mesh or less, and a titanium oxide source, which contains titanium oxide, which produces titanium oxide by heating, preferably having a size of 100 mesh or less, are mixed in a suitable mixer. A homogeneous mixture obtained by a dry mixing method using a medium such as water, or a homogeneous mixture obtained by mixing by an overflow mixing method using an appropriate mixer in a medium such as water and then removing the medium, The desired baked product is obtained by heating and baking in a heating furnace such as an electric furnace at a temperature of 600°C or higher, preferably 700 to 1400°C, more preferably 900 to 130 pi for about 150 hours to 30 minutes. It will be done.
Heat treatment temperature of zinc oxide source and titanium oxide source is 600q
o If the temperature is too high, it will take time to obtain a fired product of zinc oxide and titanium oxide. It is not desirable because it is too much. However, even if it is less than 60,000, a fired product can be obtained by heating the zinc oxide source and the titanium oxide source for a considerably long period of time. The mixture for heating and baking may also be molded under pressure. In this specification, "
"A fired product obtained by heating a mixture of a zinc oxide source and a titanium oxide source to a temperature of 60 pi or more" means that a zinc oxide source and a titanium oxide source become zinc oxide and titanium oxide, respectively, by heating, Moreover, it refers to products obtained by at least a portion of zinc oxide and titanium oxide causing some kind of reaction through heating (for example, a solid solution of zinc oxide and titanium oxide), but does not include a simple mixture of zinc oxide and titanium oxide. . The method for producing a fired product of zinc oxide and titanium oxide, as well as its magnetic properties such as dielectric loss, dielectric constant, and dielectric breakdown properties, have been studied in detail.

It is already known that the electrical properties of such a fired product of zinc oxide and titanium monoxide are completely different from those of zinc oxide alone, titanium oxide alone, or a mere mixture of the two. In addition to zinc oxide, zinc oxide sources for producing baked products include, for example, zinc hydroxide, zinc carbonate, basic box lead carbonate, zinc nitrate, zinc acetate, and the like.

In addition to titanium oxide, titanium oxide sources include titanium hydroxide. When producing a fired product of zinc oxide and titanium oxide, the mixing ratio of the zinc oxide source and titanium oxide source can be varied over a wide range depending on the purpose of the electrical insulator to be obtained. , usually contains 70 to 30 mol% of zinc oxide and 30 to 30 mol% of titanium oxide.
It is preferable to have a composition of 70 mol%.
In the present invention, it is preferable that the molar ratio of boric acid used together with the fired product in producing the heat-resistant electrical insulator is in the range of 1:0.1 to 8.0 with respect to the fired product.

If the ratio of boric acid to the fired product is less than 0.1, the mechanical properties of the resulting electrical insulator will be insufficient; In some cases, the resulting electrical insulator is unfavorable from the viewpoint of water resistance.
Note that within the range of the above-mentioned usage ratio of boric acid, a part of the boric acid can be replaced with boron oxide. As will be described later, under the manufacturing conditions of the electrical insulator of the present invention, boric acid is partially dehydrated and condensed, but the moisture generated at this time may sometimes cause voids to be formed in the electrical insulator of the present invention. By substituting a portion of boric acid with boron oxide from the beginning, the generation of voids can be suppressed. Further, a dehydrated condensate containing metaboric acids as a main component obtained by heating boric acid at a temperature of 100° C. or higher can also be used instead of boric acid. Therefore, in this specification, "boric acid" includes not only boric acid alone, but also boric acid in which a portion of boric acid is layered with boron oxide or metaboric acids. Furthermore, in this specification, the number of moles in the fired product is used in the following meaning. That is, for example, if a fired product is produced using 60 days of zinc oxide as a zinc oxide source and 402 titanium oxide as a titanium oxide source, a fired product of substantially 100 years is obtained, and Z contained therein. When converting zinc oxide into moles, the amount of zinc oxide (60)/molecular weight of zinc oxide (81.paper)
: 0.737 mol, and converting titanium oxide into moles, the weight of titanium oxide is 40)/molecular weight of titanium oxide (7)
9.90)=0.501 mole.

However, the number of 100 pieces of this fired product was 0.73710.
For convenience, it can be considered that this corresponds to 501=1.2*mol. On the other hand, since 1 mole of boric acid can be considered to be 61.82, scales and boric acid can be mixed at a desired molar ratio based on the above concept. Examples of the inorganic fibers used in the present invention include glass cloth, glass mat, asbestos vapor, asbestos, ceramic fiber, and potassium titanate fiber.

Examples of inorganic fillers used in the present invention include calcium oxide, tin oxide, magnesium oxide, aluminum oxide, zinc oxide, titanium oxide, silicon oxide, iron oxide, zirconium oxide, calcium hydroxide, aluminum hydroxide, water Iron oxide, aluminum fluoride, magnesium fluoride, boron nitride, glass powder, zirconium silicate, kaolin, calcined clay, barium titanate, talc, mica (mica), mullite, zircon sand, shirasu balloon, /miyukilite, / Examples include light.

Furthermore, examples of thermosetting resins used in the present invention include phenol resins, epoxy resins, silicone resins, polyimide resins, melamine resins, and polyester resins.

In the present invention, in addition to the binder component, the above-mentioned inorganic fibers,
By heat-treating a composition containing at least one of an inorganic filler or a thermosetting resin under pressure, a wide range of electrical insulators can be obtained by heat-treating a composition containing at least one type of inorganic filler or thermosetting resin. An electrical insulator with physical properties can be obtained.

For example, by heating a mixture of a binder, inorganic fibers, and/or inorganic filler under pressure to bind it, the mechanical properties may be better depending on the application than those made by binding only the binder. A more preferable electrical insulator is obtained. In addition, by heating a mixture of a binder and a thermosetting resin under pressure to bind the mixture, although the heat resistance is generally inferior to that of a binder alone, it is possible to Depending on the composition, an electrical insulator having favorable mechanical properties, electrical properties and water resistance can be obtained. Therefore, the mixing ratio of the binder and the above-mentioned components other than the binder can be varied over a wide range depending on the composition of the binder, the type of components other than the binder, and the use of the resulting electrical insulator. Usually, the binder is preferably in the range of 5 to 99.8 parts, and the components other than the binder are in the range of 95 to 0.2 parts, based on the weight of the electrical insulator 10. If the amount of the binder is less than 5 parts, the mechanical strength of the resulting electrical insulator will decrease, while if it is more than 99.8 parts, the intended effects of the components other than the binder will not be exerted easily. The method for manufacturing a heat-resistant electrical insulator according to the present invention will be explained below.

First, a zinc oxide generating source such as finely pulverized zinc oxide and a titanium oxide generating source such as titanium oxide are uniformly mixed in a desired ratio, and then at a temperature of 600°C or higher, preferably 600°C or higher.
A fired product of zinc oxide and titanium oxide is prepared by heating and firing at 1400 qo for about 150 hours to 30 minutes, more preferably at 900 to 1300 qo for about 5 hours to 1 hour.

The obtained baked product is crushed, mixed with a desired amount of boric acid, and further milled with a ball mill etc.
The molding composition is pulverized to a size smaller than a mesh to obtain a molding composition consisting only of a binder. A molding composition containing at least one of an inorganic filler or a thermosetting resin in addition to a binder is prepared by mixing desired amounts of a fired product, boric acid, and at least one of an inorganic filler or a thermosetting resin. Then, it is prepared by grinding it to a size of 100 mesh or less using a ball mill or the like. A molding material containing inorganic fibers is prepared by uniformly spraying the various molding compositions described above onto inorganic fibers. The molding composition obtained as described above was put into a mold, and under a molding temperature of 130 to 20 k9 and a molding pressure of 100 to 300 k9/base, about 10
When heated and pressed for ~60 minutes, a heat-resistant electrical insulator is obtained.

If the molding temperature is less than 130 points, the strength of the resulting insulator will decrease, which is undesirable, and if it is more than 20 points, the boric acid will rapidly dehydrate, causing foaming. Undesirable.

If the molding pressure is less than 100k9/flow, it is not preferable because a dense insulator cannot be obtained, and if the molding pressure is more than 300k9', there is no change in the properties of the obtained insulator, and the effect of applying high pressure is Not particularly. When heat-resistant electrical insulators are manufactured under heated and pressurized conditions, gaseous substances are generated due to thermal decomposition of boric acid or thermosetting resin contained in the binder. It is desirable to temporarily release the pressure applied to the gas to vent the gas.
The molding time varies depending on the molding temperature and molding pressure, but is approximately 10 to 60 minutes. After the electrical insulator is obtained in this way, it may be post-treated under pressure or bran pressure, preferably at a temperature higher than the forming temperature, in order to obtain dimensional stability, depending on the purpose and conditions of use. is desirable. The present invention will be explained below with reference to examples, but the present invention is not limited to the following examples.

Example: 2 moles of zinc oxide of 1200 mesh or less and 20
One mole of anatase-type titanium oxide of 0 mesh or less was suspended in about 10 times the volume of distilled water, thoroughly mixed with a high-speed mixer, and then the mixture was taken in a furnace.

The mixture was then thoroughly dried in an electric constant temperature dryer at 110°C, taken up in a Luppo, and heated in an electric muffle oven at 1200°C.
By heating and firing for more than 2 hours, a fired product of zinc oxide and titanium oxide was obtained.
It was ground to 0 mesh or less. 70 parts of this pulverized fired product and 25 parts of boric acid pulverized to 200 mesh or less were uniformly mixed to obtain a molding composition consisting of only a binder. This molding composition 509 was put into a round mold with a diameter of 9 mm, and heated under pressure at 170° C. and 300 k9/metre for 5 minutes.

Then, the pressure was released for 1 minute to degas. Thereafter, after heating at a pressure of 100k9/hot water for 1 minute, the pressure 4 was released and degassing was performed for 1 minute. This operation was repeated twice. Next, pressure heating at 200k9' was carried out for 1 minute, and degassing was similarly carried out for 1 minute. This operation 2
Repeated times. Further, the pressurized heating and degassing operations were repeated twice under a pressure of 300 k9/kg. In the end, after degassing a total of 7 times at each pressure, the primary molded product was finally obtained by hot pressing for 1 hour at a pressure of 300k9/kg from the initial mold setting. . The primary molded product was heat-treated at 300° C. for 5 hours in an electric furnace to obtain a secondary molded product with a thickness of 3 bars for evaluation of physical properties. This molded article was significantly easier to process into a desired shape than conventional alumina porcelain insulators. Example
2 A molding composition was prepared, molded, and post-treated in exactly the same manner as in Example 1, except that 1 mol of zinc carbide and 1 mol of anatase titanium oxide were used.
A next molded product was obtained.

Example 3 A molding composition containing an inorganic filler was prepared by uniformly mixing 9 parts of the molding composition powder prepared in Example 1 and 10 parts of mica of 200 mesh or less.

This molding composition was molded and post-treated in exactly the same manner as in Example 1 to obtain a secondary molded product for physical property evaluation. Example 4 95 parts of the molding composition powder prepared in Example 1 and 5 parts of epoxy resin pulverized to 200 mesh or less were uniformly mixed to prepare a molding composition containing a thermosetting resin.

This molding composition was molded in exactly the same manner as in Example 1 to obtain a primary molded product. The primary molded product was heat treated in an electric furnace at 200 pm for 5 hours to obtain a secondary molded product for physical property evaluation.

0 Example 5 Glass chopped strand pine cut into 150 x 150 fences was prepared in step 1, and molding composition powder consisting only of the binder prepared in Example 1 was sprinkled on each mat. , two glass cloth mats were stacked on top and bottom to remove dust.

The amount of sprayed was the same weight as the total amount of glass fiber. The obtained laminated product was placed in a mold, set at a temperature of 170°C, and
The single pressure heat treatment in step 4 was carried out at a pressure of 00k9'.
During this time, degassing was performed several times. The thus obtained primary molded product was heat-treated at 300° C. for 5 hours to obtain a secondary molded product for physical property evaluation. Example 6 3 parts: 94 parts of the molding composition powder consisting only of the binder prepared in Example 1, a female part of epoxy resin pulverized to 200 mesh or less, and 2 parts of thermosetting silicone resin pulverized to 200 mesh or less. 5 parts of the mixed powder obtained by uniformly mixing the powder was spread over 4 pieces of glass fiber in exactly the same manner as in Example 5, and the obtained laminate was molded in the same manner as in Example 5. A primary molded product was obtained.

The primary molded product was heat treated at 20,000 for 5 hours to obtain a secondary molded product for physical property evaluation.

Table 1 shows the physical property values obtained for each electrical insulator thus obtained.

Table 1

Claims (1)

[Claims] 1. A fired product obtained by heating a mixture of a zinc oxide source and a titanium oxide source to a temperature of 600°C or higher and a composition containing boric acid as an essential component are heated under pressure and bound together. A heat-resistant electrical insulator. 2. A group consisting of a fired product obtained by heating a mixture of a zinc oxide source and a titanium oxide source at a temperature of 600°C or higher, a composition containing boric acid as an essential component, an inorganic fiber, an inorganic filler, and a thermosetting resin. A heat-resistant electrical insulator formed by heating and bonding together at least one material selected from the following.