JPS6110922B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method of treating the surface of an inorganic material with an organosilicon-based curable substance, and more specifically, the above treatment improves the bonding properties of the inorganic materials with each other or with an organic resin, thereby improving heat resistance and moisture resistance. ,
The present invention relates to a method for forming an electrically insulating material with excellent electrical insulation and mechanical strength. Conventionally, inorganic materials have been processed to make them heat resistant, moisture resistant,
Several proposals have been made as methods for obtaining electrically insulating materials with excellent electrical properties. That is, (a) a method for producing silicone mica tapes and silicone mica plates with excellent water resistance bonded with silicone varnish by treating a laminated mica foil with a 3 to 4% by weight toluene solution of oxime silane (Japanese Patent No. 820879). ), (b) In order to improve the adhesion between glass fibers and polymers in glass-reinforced thermosetting resins and glass-reinforced thermoplastic resin composites, the general formula R ⁶ SiX ₃ (wherein R ⁶ is amino treatment of glass fibers with a silicone monomer having an organic functional group such as a mercapto group, a vinyl group, an epoxy group, or a methacryloxy group, where X represents a silicon-bonded hydrolyzable alkoxy group. There is a way to do it. In method (a), laminated mica foil is produced by pulverizing raw mica into flakes by firing or not firing it, dispersing it in water, and then using a paper-making machine. Since the treatment liquid is not soluble in water, it cannot be treated during the production of laminated mica foil, and there is the inconvenience of having to carry out the treatment in a post-treatment process, making it impossible to shorten the manufacturing process and the number of man-hours. Therefore, it has been desired to develop a treatment agent that is soluble in water. In method (b), reinforcing materials or fillers such as glass fibers and various inorganic fillers are treated with various silane monomers diluted with water in order to improve the bonding strength of composite materials made of organic polymers. The method uses an aqueous solution of conventionally used silane monomers such as γ-aminopropyltriethoxysilane, vinyltrichlorosilane, γ-methacryloxypropyltrimethoxysilane, and γ-glycidoxypropyltrimethoxysilane at a concentration of 5% by weight. % or less, it has the disadvantage of being unstable. In addition, these silane monomers are not sufficiently effective for laminated mica foils, and are not used for silicone mica products except when a special addition-polymerizable silicone varnish is added and used as an adhesive for laminated mica foils. Not yet. In order to improve the above-mentioned drawbacks, the present invention has developed a silicone composition that is a water-soluble solution that is stable even at relatively high silane concentrations, is easy to treat inorganic materials, and has excellent reactivity with organic resins. As a result of research on the object, the present invention is proposed. A mixture of oxime silane or a partial hydrolyzate thereof and an amino group-containing silane or a partial hydrolyzate thereof, or an aqueous solution containing the reaction product thereof as a main component, has excellent properties for modifying the surface of inorganic materials. It has been discovered that by improving the reactivity with resin, it is possible to produce an electrically insulating material with excellent heat resistance, moisture resistance, electrical insulation, and mechanical strength. In addition, as in the present invention, oxime silane is used in alkyd resins, polyester resins, polyether resins, epoxy resins, phenol resins,
and a hydroxyl group-containing paint resin modified with silicone, polyamide, etc., and an oxime silane having at least two oxime groups in one molecule directly bonded to a silicon atom, in an amount of 1 mole or more of oxime silane per hydroxyl group in the resin. A method for forming a coating film with excellent storage stability and room-temperature curability using a coating resin composition containing
101234). However, this uses oxime silane as a curing accelerator for silicone resins for paints, and does not mention the improvement of moisture resistance through treatment of inorganic materials. That is, the present invention provides an inorganic material having the general formula R ¹ _o Si(ONCR ² R ³ ) _4-o (wherein R ¹ is a monovalent hydrocarbon group, and R ² and R ³ are mutually oxime silane or its partial hydrolyzate represented by a monovalent group selected from the group consisting of a hydrogen atom and a monovalent hydrocarbon group, where n is the same or different from the group consisting of a hydrogen atom and a monovalent hydrocarbon group, where n represents an average number of 0 to 2; 1 part by weight and (2) general formula ANHR ⁴ Si
(OR ⁵ ) ₃ (wherein A is a monovalent group selected from the group consisting of a hydrogen atom, an alkyl group and an aminoalkyl group, R ⁴ is a divalent hydrocarbon group, and R ⁵ are the same or different) A mixture obtained by mixing 1 to 10 parts by weight of a different amino group-containing silane (representing an alkyl group having 1 to 2 carbon atoms) or a partial hydrolyzate thereof in an aqueous solvent, and (1) The present invention relates to a method for treating an inorganic material, characterized in that it is treated with an organosilicon-based curable substance selected from the group consisting of the reaction products of (2). Examples of inorganic materials used in the present invention include peelable mica, mica foil such as laminated mica, asbestos, and glass cloth. Among these inorganic materials, hard muscovite-based laminated mica foil is often used as an electrical insulating material because of its excellent workability and economical efficiency, but its moisture resistance is poor. The organosilicon-based curable substance used in the present invention acts very effectively on this moisture resistance modification. Although asbestos has lower moisture resistance than laminated mica foil, the same effect can be achieved in this case as well. The organosilicon-based curable substance used in the present invention is a mixture or reaction product of (1) oxime silane or its partial hydrolyzate and (2) amino group-containing silane or its partial hydrolyzate. , the above (1), (2), or both may coexist in the reaction product. The oxime silane (1) is
General formula R ¹ _o Si(ONCR ² R ³ ) _4-o (where R ¹ , R ² , R ³
and n are as described above),
Examples of the monovalent hydrocarbon group represented by R ¹ include a methyl group, a vinyl group, and a phenyl group, but the methyl group is the most common because the raw material is easily obtained. Moreover, these may be used in combination of the same type or different types. R ² and R ³ are hydrogen atoms or monovalent hydrocarbon groups, and examples thereof include methyl, ethyl, propyl, butyl, and cyclohexyl groups, and the same or different types may be used in combination. . n is 0
-3, and may be the same or a mixture of different ones, but in order to obtain good curability, the average
Must be in the range 2. Furthermore, n=1
It is preferable that This oxime silane is
It can be easily manufactured as follows. For example, silicon tetrachloride, chlorosilanes such as methyltrichlorosilane, dimethyldichlorosilane, trimethylchlorosilane, phenyltrichlorosilane, diphenyldichlorosilane, vinyltrichlorosilane, methylvinyldichlorosilane, or mixtures thereof, and acetoxime, methyl ethyl keto It is obtained by subjecting oximes such as oxime, butyraldoxime, and methylbutylketoxime to a dehydrochlorination reaction in the presence of a hydrochloric acid scavenger such as pyridine. It is practical to dissolve the oxime silane or its partial hydrolyzate thus obtained in a soluble solvent and use it as a solution adjusted to a concentration of 10 to 30% by weight. Concentration is 10% by weight
If the concentration is less than 30% by weight, a large amount of solvent is used, resulting in poor efficiency, and if the concentration exceeds 30% by weight, gels are likely to form when mixed with component (2), which will be described later. The solvent may be anything as long as it is miscible with water and component (1), such as methanol, ethanol,
Examples include monohydric alcohols such as isopropanol and acetone, but it is preferable to use monohydric alcohols that have low flammability and are easy to handle. The amino group-containing silane (2) has the general formula ANHR ⁴ Si
(OR ⁵ ) ₃ (in the formula, A, R ⁴ and R ⁵ are as described above), where A can be a hydrogen atom, an alkyl group such as a methyl group, an ethyl group or a propyl group, or a β Examples include aminoalkyl groups such as -aminoethyl group. Hydrogen atoms are the most common because raw materials are easily available and they work effectively. Divalent hydrocarbon groups represented by R ⁴ include methylene group, ethylene group, propylene group,
Examples include butylene groups, but ease of synthesis,
A propylene group is preferred because it has excellent stability in an aqueous solution. OR ⁵ is a methoxy group or an ethoxy group. Examples of the amino group-containing silane include γ-aminopropyltriethoxysilane and γ-aminopropyltrimethoxysilane. Further, by adding a small amount of water to these amino group-containing silanes and heating them, partial hydrolysis condensation can be carried out to convert part or all of the silanes into amino group-containing siloxanes. The solution (1) is gradually added dropwise to a solution in which such an amino group-containing silane or a partially hydrolyzed product thereof is dissolved in an aqueous solvent and adjusted to a concentration of preferably 5 to 10% by weight. If the concentration exceeds 10% by weight, a reaction occurs rapidly when (1) and (2) are mixed, and unless the reaction is controlled, undesirable side reactions are likely to occur. Moreover, if it is less than 5% by weight, the concentration of the product becomes too thin, resulting in poor processing efficiency.
Examples of the aqueous solvent include water, monohydric alcohols, and mixtures thereof; however, since these amino group-containing silanes and their partial hydrolysates dissolve in water, it is advantageous to use water. be. Since water generates heat when added dropwise, it is necessary to gradually cool it while mixing to prevent sudden heat generation. At this time, some water-insoluble gel is generated, but this can be easily removed by passing it through paper or a wire mesh of 200 mesh or more.A transparent and stable organosilicon-based curable material is obtained, and if necessary Alternatively, it can be easily diluted with alcohol and used. In this way, an organosilicon-based curable substance can be obtained by mixing (1) oxime silane or its partial hydrolyzate with (2) amino group-containing silane or its partial hydrolyzate. can. During mixing, part or all of them may be reacted to form a condensate containing both oxime groups and amino groups, and such reaction products and components (1), (2), Or, it is okay to let both of them coexist. This reaction is accelerated by increasing the drop temperature. However, if the reaction proceeds too much, a polymer substance that is insoluble in water or an aqueous solvent will be produced, so the reaction must be controlled. The ratio of component (1) and component (2) used in the organosilicon-based curable material thus obtained is 1 to 10 parts by weight, preferably 1 to 10 parts by weight of component (2) to 1 part by weight of component (1).
It ranges from 1.5 to 5 parts by weight. If the amount of component (1) is too small than this range, excellent treatment effects such as imparting water resistance cannot be obtained, and on the other hand, if it is too large, the curable substance becomes unstable and a gel-like substance insoluble in water is generated. This is because it is easy to do. The content of the main components in the curable material is suitably in the range of 2 to 4% by weight for component (1) and 4 to 9% by weight for component (2). If it is less than this range, the effect of imparting water resistance will be small, and if it exceeds this range, gel-like substances will be likely to occur and it will be unstable. The organosilicon-based curable substance thus obtained can be used in the form of an aqueous solution to improve the surface of inorganic materials. That is, an organosilicon-based curable substance is attached to the surface of an inorganic material by impregnation or coating as an aqueous solution, and then the aqueous solvent is removed by drying to form a cured film.
For impregnation and application, recommended methods include, for example, adding it to an aqueous solution during mica foil papermaking, using a treatment liquid bath, and spraying. Drying is usually at 80-150℃ for 10~
30 minutes is enough. The amount of hardenable substance attached to inorganic material is
The amount may be about 0.05 to 0.2% by weight; if the amount is too small, a sufficient treatment effect will not be obtained, but if it is too large, the treated inorganic material will become hard, making it impossible to obtain insulating chips with good flexibility. The thus obtained inorganic material modified with a cured film may be used as it is, or may be pressure-molded and used as a moisture-resistant inorganic material. By treating the material with an organic resin, the bond strength between the organic resin and the inorganic material can be increased. Examples of organic resins include silicone resins modified with organic resins such as silicone resins, epoxy, and polyesters, and thermosetting resins such as imide resins, epoxy resins, polyester resins, and polyether resins. In addition, the curable substance of the present invention acts very effectively and promotes curing of the resin if there is a hydroxyl group in the molecule of these thermosetting resins. The organosilicon-based curable material of the present invention is based on oxime silane, which has a useful effect on mica foil, but this problem was solved by blending it with aminosilane, another useful ingredient, to make it water-soluble. . Excellent effects can be easily obtained by adding this organosilicon-based curable substance to the water dispersion of mica foil raw materials during papermaking of laminated mica foil, or by spraying it before the drying process of laminated mica foil during papermaking. It will be done. Furthermore, since this organosilicon-based curable substance is also soluble in alcohols, this alcohol diluted solution can be used in the same manner as a conventional toluene solution of oxime silane to obtain the same effect. As mentioned above, the present invention is to improve the surface of inorganic materials such as mica and asbestos with a water- or alcohol-soluble organosilicon hardening substance, which has excellent processability and also has hydroxyl groups used as a matrix. Adhesion is improved by accelerating the curing of thermosetting resin materials such as silicone resin, polyimide resin, epoxy resin, and polyester resin, which improves heat resistance, moisture resistance, electrical insulation,
An electrically insulating material with excellent mechanical strength can be obtained. Therefore, the present invention has the following features. (1) Compared to conventional processing methods, the inorganic material and organic resin react effectively with each other, resulting in an excellent electrically insulating material. (2) Curable substances have good storage stability and can be diluted with water or alcohol if necessary, making them economical and extremely easy to handle. (3) When making paper by dispersing mica foil raw materials in water, such as laminated mica foil, it is possible to add a curable substance to the papermaking water or to easily spray it during paper making, which can be used to improve laminated mica foil. Useful. Therefore, the present invention provides silicone resin mica laminates, silicone resin mica tapes, silicone resin asbestos boards, silicone resin glass laminates, silicone resin glass tapes, and corresponding epoxy resin-impregnated substances, polyester resin-impregnated substances, etc. Used in manufacturing. Hereinafter, the effects of the present invention will be illustrated by Examples and Comparative Examples. In addition, in the following examples and comparative examples, all parts represent parts by weight. Example 1 3 parts of methyltris(methylethylketoxime)silane was dissolved in 10 parts of methanol, and 7 parts of γ-aminopropyltriethoxysilane was dissolved in neutral water.
The former solution was gradually added dropwise to the latter solution while stirring to avoid sudden heat generation, and the mixture was stirred and passed through a 200-mesh wire gauze to prepare a transparent curable material. This curable material contains 3% by weight of oxime silane and 7% by weight of amino group-containing silane, has a specific gravity of 0.990 (at 25°C), and a hydrogen ion concentration of 10.6. The obtained curable substance was diluted approximately 50 times with water,
It was spray applied to a hard laminated mica foil with a thickness of 0.08 mm so that it adhered at 0.2% by weight, and dehydrated and dried at a temperature of 110°C for 10 minutes. Afterwards, silicone varnish
A 20% by weight toluene solution of TSR125 (trade name of Toshiba Silicone Corporation) resin was applied to a laminated mica foil at 10% by weight and dried at a temperature of 100°C for 10 minutes. The laminated mica prepreg material treated in this way was
The sheets were piled up, and a pressure of 55 kg/cm ² was applied and held for 45 minutes on a hot plate at 180°C to produce a silicone mica plate. Also, for comparison, instead of the above-mentioned hardening substance,
The same conditions were used except that a 3% by weight toluene solution of methyltris(methylethylketoxime)silane (Comparative Example 1) and a 3% by weight toluene solution of γ-aminopropyltriethoxysilane (Comparative Example 2) were used.
In addition, silicone mica plates were manufactured under the same conditions except that no pretreatment was performed (Comparative Example 3). These silicone mica plates were immersed in water and the water absorption rate, bending strength after immersion in water, and changes in properties after high-temperature heating at 230°C for 48 hours were measured, and the results are shown in Table 1.
It was as shown in. In addition, in the table, the adhesion amount of the pretreatment agent is weight % with respect to the weight of mica, and the adhesion amount of silicone resin is the weight % of the silicone resin in the silicone mica plate.

【table】

[Table] Example 2 Using the curable material of Example 1, the thickness was determined in the same way.
Two sheets of 0.04 mm laminated mica foil spray-coated and dried and one sheet of 0.03 mm thick glass cloth were layered together and silicone varnish TSR117 was applied.
A 40% by weight xylene solution (trade name of Toshiba Silicone Co., Ltd.) was applied at a rate of 330g/ ^m2 , and
After drying for a minute, it was cut into 15 mm width to produce a highly flexible silicone mica glass tape. 1/2 wrap the silicone mica glass tape obtained above onto a 5 x 18 x 350 mm aluminum bar.
After creating a model insulated coil wound four times to a length of 200 mm, it was heat-treated at 150°C for 20 hours to integrate silicone mica glass. Next, as shown in Figure 1, a 100 mm wide electrode was placed on this insulating layer and left in a humidity of 95% RH to measure the change in insulation resistance depending on the number of days of moisture absorption. The measurements shown were obtained. In the insulated model coil shown in FIG. 1, 1 is a silicone mica glass tape, 2 is a guard electrode (aluminum foil), 3 is a side electrode (aluminum foil), and 4 is a side electrode (aluminum conductor). For comparison, the change in insulation resistance with the number of days of moisture absorption was measured under the same conditions for a silicone mica glass insulation structure manufactured under the same conditions as in the above example except that no pretreatment with a hardening substance was performed.The results are as follows.
It was as shown in curve B in Figure 2. As is clear from FIG. 2, in the case of the present invention, it was possible to obtain a silicone mica product with little decrease in resistance value and excellent water resistance. Example 3 Using a diluent obtained by diluting the hardening substance of Example 1 approximately 30 times with methanol, 0.8 mm thick asbestos paper Vestron GT-8 (trade name of Jones Manville Co., Ltd.) was impregnated with 100 Dry for 20 minutes at °C. The amount of curable material deposited after drying was 0.63% by weight. After that, a 30% by weight toluene solution of silicone varnish TSR125 was added to Vestron GT-8.
A silicone asbestos board was manufactured by applying 28% by weight of the silicone asbestos to the silicone asbestos, drying it at 100°C for 15 minutes, stacking 10 sheets together and applying a pressure of 100 kg/cm ² on a hot plate at 180°C and holding it for 1 hour. For comparison, asbestos paper was similarly treated with a 3% methanol solution of methyl tris (methyl ethyl ketoxime silane) instead of the above-mentioned hardening substance (Comparative Example 4), and asbestos paper was not pretreated (Comparative Example 4). As for Comparative Example 5), a silicone asbestos board was manufactured under the same conditions. The properties of these silicone asbestos boards are shown in Table 2.
It was as shown in.

[Table] Example 4 An epoxy mica glass tape was produced in the same manner as in Example 2 except that epoxy resin was used instead of silicone varnish TSR117. However, the following formulation of epoxy resin should be used, and the
A prepreg was prepared by drying for a minute. Epicoat 1001 (trade name of Ciel Kagaku Co., Ltd.) 80 parts Epicoat 154 (trade name of Ciel Kagaku Co., Ltd.) 20 parts dicyandiamide 4 parts benzyldimethylamine 0.2 parts ethylene glycol monomethyl ether Approximately 80 parts The epoxy mica glass tape obtained in the above manner was used as an example. A model insulated coil was created in the same manner as in 2, and then heat treated at 160°C for 1 hour to integrate the epoxy mica glass. Next, in the same manner as in Example 2, changes in insulation resistance against humidity were measured, and measured values as shown by curve C in FIG. 3 were obtained. For comparison, the moisture resistance change in insulation resistance was measured under the same conditions for an epoxy mica glass insulation structure obtained by manufacturing under the same conditions as above except that no pretreatment with a hardening substance was performed. It was as shown by curve D in FIG. As in Example 2, when the method of the present invention was used, it was possible to obtain an epoxy mica product with little decrease in resistance, good compatibility with epoxy resin, and excellent water resistance. Example 5 Curable substances 51 to 56 were prepared in the same manner as in Example 1 using the raw materials shown in Table 3. However, the partial hydrolyzate of γ-aminopropyltriethoxysilane used for curable substance 51 was prepared by mixing 100 parts of the silane with 11 parts of water.
The mixture was heated at 75 to 80° C. for 1 hour while distilling off the ethanol produced, and the resulting product was used as it was. Using the curable material obtained in this way, a silicone mica plate with a thickness of 0.5 mm was manufactured in the same manner as in Example 1, and its water absorption rate, change in bending strength due to water immersion, and moisture absorption volume resistivity. When the subsequent changes were measured, the results shown in Table 4 were obtained.

【table】

【table】

[Table] Example 6 Two parts of methyltris(methylethylketoxime)silane were added to 30% of ethanol containing 0.5% by weight of water.
7 of γ-aminopropyltriethoxysilane while heating and stirring to the reflux temperature of ethanol.
was added dropwise to partially co-hydrolyze both silanes, and a small amount of by-produced gel was separated to obtain an ethanol solution of a co-condensate of both silanes. A silicone mica glass tape was produced in exactly the same manner as in Example 2, except that this diluted with 59 parts of water was used as the curable material. The insulation resistance of the silicone mica glass tape obtained in this way was measured in the normal state and after being left in a humidity of 95% RH for 28 days.
They were 2.8×10 ¹³ Ω and 1.0×10 ¹² Ω. Example 7 5 parts of unfired mica pieces obtained by physically cutting muscovite-based hard mica scraps into pieces in a forced water stream were dispersed in 95 parts of water, and 1 part of the curable material prepared in Example 1 was added to this. Add and stir. By using this dispersion to make a laminated mica foil in a conventional manner using a circular mesh paper machine, a laminated mica foil having a thickness of 0.12 mm with about 0.2% of the curable substance adhered to the surface of the mica pieces was obtained. The curable material was cured by heating this at a temperature of 100° C. for 10 minutes. This thing is
Compared to laminated mica foil to which no hardening substance is attached, it has lower water absorption and excellent moisture resistance. That is, one end in the length direction of a test piece made by cutting a laminated mica foil made by adding a curable substance and a laminated mica foil obtained without adding a curable substance to a size of 30 mm x 100 mm for comparison. When moistened with water, the comparative laminated mica exhibited a water wicking phenomenon, whereas the laminated mica foil made by adding a hardening substance did not exhibit the water wicking phenomenon, and No peeling phenomenon was observed. In addition, the contact angle of water droplets on the surface of the test piece placed horizontally was 90°, and no wetting phenomenon due to water was observed. Example 8 Unfired mica piece 5 similar to that used in Example 7
When making laminated mica foil using a circular wire paper machine from 95 parts of water and 95 parts of water, in a wet state before the winding process,
By spraying 0.3 part of the treatment solution obtained by diluting the curable substance prepared in Example 1 approximately 30 times with water, the surface was coated with a thickness of 0.08 cm with 0.2% of the curable substance attached.
A laminated mica foil of mm was obtained. This at a temperature of 100℃
When heated for 10 minutes to cure the curable material, the laminated mica foil exhibited excellent water resistance. This laminated mica foil was coated with silicone varnish TSR125 and cured in the same manner as in Example 1, and measured under the same conditions as in Example 1. The volume resistivity after moisture absorption was 8.8×10 ¹⁵ Ω・cm; The water absorption rate after high temperature heating was 0.87%.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a silicone mica tape insulation model coil, and the dimensions are in mm. Second
The figure is a graph showing the relationship between the number of days of moisture absorption and the insulation resistance of a silicone mica glass tape insulation model coil. Glass tape and B are graphs of model coils made using a silicone mica glass tape that was not treated with a curable substance.
FIG. 3 is a graph showing the relationship between the number of days of moisture absorption and insulation resistance of an epoxy mica glass tape insulation model coil. In FIG. D is a graph of a model coil created using an epoxy mica glass tape and an epoxy mica glass tape that is not treated with a curable substance. 1... Silicone mica glass tape, 2...
Guard electrode (aluminum foil), 3... side electrode (aluminum foil), 4... side electrode (aluminum conductor).

Claims (1)

[Claims] 1. An inorganic material having the general formula R ¹ _o Si
(ONCR ² R ³ ) _4-o (wherein R ¹ is a monovalent hydrocarbon group,
R ² and R ³ are monovalent groups selected from the group consisting of a hydrogen atom and a monovalent hydrocarbon group, which are the same or different from each other; n is an oxime represented by an average number of 0 to 2; 1 _part by weight ^of silane or its ^partial hydrolyzate; , R ⁴ is a divalent hydrocarbon group, R ⁵ is the same or different alkyl group having 1 to 2 carbon atoms) or a partial hydrolyzate thereof, 1- 10 parts by weight in an aqueous solvent, and an organosilicon-based curable substance selected from the group consisting of the reaction products of (1) and (2) above. A method for processing inorganic materials. 2. The treatment method according to claim 1, wherein (1) is oxime silane. 3. The treatment method according to claim 1, wherein R ¹ in (1) is a methyl group. 4. The processing method according to claim 1, wherein n in (1) is 1. 5. The treatment method according to claim 1, wherein (2) is an amino group-containing silane. 6. The treatment method according to claim 1, wherein R ⁴ in (2) is a propylene group. 7. The treatment method according to claim 1, wherein (1) is used as a 10 to 30% by weight monohydric alcohol solution. 8. The treatment method according to claim 1, wherein A in (2) is a hydrogen atom. 9. The treatment method according to claim 1, wherein (2) is used as a 5 to 10% by weight aqueous solution. 10(2) in an amount of 1.5 to 5 parts by weight. 11. The treatment method according to claim 1, wherein mica is used as the inorganic material. 12. The treatment method according to claim 1, wherein asbestos is used as the inorganic material. 13 The amount of hardenable substance adhered to is 0.05 to 0.05 of that of inorganic materials.
The treatment method according to claim 1, wherein the amount is 0.2% by weight. 14. The treatment method according to claim 1, wherein the inorganic material is treated with an organosilicon curable substance and then further treated with an organic resin. 15. The treatment method according to claim 14, wherein the organic resin is a silicone resin. 16. The treatment method according to claim 14, wherein the organic resin is an epoxy resin.