JPS6311479B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to sheets. More specifically, it is a sheet made of a mixture of short fibers and pulp-like particles formed by covering and connecting potassium titanate fibers with a heat-resistant aromatic polymer, and has high temperature resistance and electrical insulation properties. , has excellent dimensional stability, low moisture absorption, mechanical properties, flame resistance, flame retardancy, etc., for example, electrical insulation paper, interior materials such as wallpaper, friction materials such as brake linings and clutch facings, high temperature gaskets, etc. This sheet is useful for packing, covering material, insulation material, battery separator, sound absorbing material, etc. Conventionally, pulp-like particles used in paper include:
Wood pulp is the most widely known and has been used in large quantities as electrical insulating paper, but it has major drawbacks such as high hygroscopicity, poor heat resistance, and poor dielectric properties. As a result, it is no longer possible to meet the performance requirements for reducing the size and weight of electrical equipment such as electric motors, generators, and transformers.
Recently, pulp-like particles obtained from synthetic polymers have been attracting attention as a material for electrically insulating paper due to their excellent heat resistance and electrical insulation properties. Various proposals have been made. For example, Japanese Patent Publication No. 35-11851 describes paper pulp particles made only of synthetic polymers. However, when the above-mentioned paper pulp particles are processed and used as electrically insulating paper, impregnating properties,
It has the disadvantage of insufficient heat resistance, flame resistance, and dimensional stability. In particular, when reducing the size and weight of electrical equipment such as electric motors and generators, electrical insulating paper with excellent heat resistance and impregnation properties is required, but the heat resistance and impregnation properties of the paper pulp particles described above are still insufficient. It is insufficient. Furthermore, Japanese Patent Publication No. 43-20421 describes a high-temperature-resistant sheet-like structure suitable for electrical insulation consisting of an entangled mixture of granular mica and substantially unfused aromatic polyamide fibrils. ing. However, the sheet-like structure described herein also has insufficient impregnability and mechanical properties as an electrical insulating material for electrical equipment that should be made smaller and lighter. Furthermore, when producing such a sheet-like structure, the mica and the fibrids separate, making the papermaking process extremely difficult. or,
Such a sheet-like structure also has the disadvantage that the mica easily peels off due to friction. In addition, in Special Publication No. 14761, 10 to 50 wt%
The particles are made of asbestos fibers and 90 to 50 wt% of aromatic polyamide with a glass transition temperature of 250°C or higher, and the asbestos fibers are coated with the aromatic polyamide, and the coated particles are pulp. Pulp-like particles are described which can be dispersed in a uniform manner. Although the paper obtained by processing these pulp-like particles has excellent heat resistance, dimensional stability, etc., asbestos powder scattered during production is harmful to workers in terms of health and safety, and is therefore undesirable. Despite the drawbacks of asbestos fibers, asbestos paper has been used for insulation materials, building materials, friction materials, electrical insulation materials, etc., taking advantage of its sheet properties, flexibility, arc resistance, corona resistance, etc. However, the characteristics of asbestos fibers have not been fully utilized because the binder lacks heat resistance or has low mechanical strength.
In order to increase the mechanical strength of asbestos paper, a method has been used to increase the binder content, but this method has the drawback of decreasing folding durability. Furthermore, sheets made mainly of asbestos fibers have conventionally been used to protect human bodies, combustible materials, equipment, etc. from slag that is scattered during welding and cutting operations. However, conventional sheets made mainly of asbestos fibers have poor mechanical properties, water resistance, etc.
When a high-temperature slag that lacks durability scatters and collides with the sheet, the impact causes the slag to penetrate through the sheet, and there is a strong possibility that the object to be protected beneath the sheet surface will be stained or burned. Furthermore, ceramic fibers are dispersed in water,
Fireproof materials and heat insulating materials formed by papermaking methods are well known. When colloidal silica or colloidal alumina is used alone as a binder to maintain the shape of such a molded product, the resulting molded product has no flexibility and is extremely brittle. Usually, an organic binder such as latex is mixed. However, conventionally used organic binders lack heat resistance, which limits their use in high-temperature locations. In addition, many conventionally used organic binders are inferior in terms of flame resistance, which limits their use as sheets to protect from slag that is scattered during welding and cutting operations, for example. On the other hand, the use of potassium titanate fibers as one of the fiber components constituting synthetic paper is already known, for example, from JP-A-49-134757 and JP-A-49-134758. These conventional techniques mix pulp-like particles and potassium titanate fibers to make paper, and since the shape of the potassium titanate fibers is smaller than the opening of the paper-making wire mesh, the potassium titanate fibers are separated from the paper-making wire mesh. It is not always satisfactory because the potassium titanate fibers may leak or the potassium titanate fibers may be unevenly distributed due to the difference in specific gravity between the pulp particles and the potassium titanate fibers. Also, properties such as strength and elongation were not sufficient. As a result of intensive research in order to eliminate these drawbacks of the conventional technology, the present inventor dissolved a heat-resistant aromatic polymer in its solvent, added potassium titanate fiber to the mixed solution, and mixed it into a precipitant. introduced,
By precipitating the potassium titanate fibers as particles, pulp-like particles are obtained in which the potassium titanate fibers are covered with an aromatic polymer and connected to each other. The sheets obtained using these pulp-like particles have excellent paper-making properties without leaking, and the sheets obtained using these pulp-like particles have electrical insulation properties,
The present invention was completed based on the finding that it has excellent heat resistance, dimensional stability, flame resistance, mechanical properties, etc. That is, the present invention consists of potassium titanate fibers and a heat-resistant aromatic polymer, and the pulp-like particles 5 to 5 are formed by covering and connecting the potassium titanate fibers with the heat-resistant aromatic polymer.
This sheet is made by mixing 95% by weight of short fibers and 95-5% by weight of short fibers. The sheet of the present invention is not only used for electrical insulating paper, but also for friction materials such as brake linings and clutch ace, making use of its excellent heat resistance, flame resistance, and mechanical properties; for interior materials of automobiles, aircraft, houses, etc.; It can be widely used for wet heat exchange elements; molded products, etc. The pulp-like particles used in the present invention are minute particles with no rigidity that are in the form of fibers, ribbons, or rods with many tentacle-like protrusions, and have a large surface area per volume, and are deposited on a wire mesh. It has the ability to form a paper-like structure. Potassium titanate fiber The potassium titanate fiber contained in the pulp particles used in the present invention contains K ₂ CO ₃ and KOH.
Using TiO ₂ as a starting material, sintering method, flux method,
General formula obtained by melting method, hydrothermal method, etc.
It is a fibrous crystal expressed by K ₂ O・nTiO ₂ . The diameter of the fibers is around 1 μm, and the length is from several μm to several mm. Further, the amount of potassium titanate fibers in the pulp particles can be arbitrarily selected depending on the use of the sheet, but is preferably 10 to 85% by weight. If the amount is less than 10% by weight, the addition of potassium titanate fibers will have no effect and dimensional stability will deteriorate. 85 on the contrary
If it exceeds % by weight, the strength and elongation mechanical properties deteriorate, and the viscosity of the mixture when potassium titanate fibers are added to the aromatic polymer solution increases extremely, making it impractical. Furthermore, inorganic fine particles such as alumina, silica, kaolin, talc, and mica may be added and mixed simultaneously with the potassium titanate fibers. Furthermore, glass fiber, rock wool, mineral wool, fused silica fiber, glassy silica fiber, kaolin fiber, ceramic fiber, bauxite fiber,
Alumina fiber, kyanite fiber, boron fiber,
One or more types of inorganic fibers such as titanium oxide fibers and magnesia fibers may be mixed with potassium titanate fibers. Aromatic Polymer Examples of the aromatic polymer having heat resistance according to the present invention include the following. 1 Aromatic polyamide (1) A condensation polyamide of a dicarboxylic acid having an aromatic ring (preferably a highly active derivative such as an acid halide) and a diamine having an aromatic ring. For example, as a dicarboxylic acid, terephthalic acid,
Isophthalic acid, etc., a type of diamine using metaphenylene diamine, 4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenylmethane, xylylene diamine, N-methyl-para-phenylene diamine, etc. It may be a homopolymer consisting of a dicarboxylic acid and one type of diamine, or it may be a copolymer of two or more compounds of either or both of the dicarboxylic acid component and the diamine component. Typical examples include polymetaphenylene isophthalamide, a copolymer of metaphenylene diamine, isophthalic acid and terephthalic acid, and poly-N-methylparaphenylene terephthalamide. (2) A polyamide in which an aminocarboxylic acid having an aromatic ring is preferably activated and condensed. For example, the aminocarboxylic acid may be a homopolymer consisting of only one type of aminocarboxylic acid such as para- or meta-aminobenzoic acid or para-aminomethylbenzoic acid, or a copolymer of two or more types of aminocarboxylic acids. A typical example is a condensate of para-aminobenzoic acid. (3) A polyamide obtained by copolymerizing the above (1) and (2). A typical example is a polyamide obtained by condensing three components: metaphenylenediamine, isophthalic acid chloride, and para-aminobenzoic acid chloride hydrochloride. 2 Nitrogen-containing polyheterocyclic compound (1) Aromatic polyamideimide Formula

[Formula] [R:

[Formula]X:-O-,= _SO2- ,

[Formula] Lower alkylene group] Polyamideimide having a unit represented by the following. These may have an inert substituent such as a methyl group, an alkoxyl group, or a halogen atom. (2) Aromatic polyamide hydrazide formula

A polyamide hydrazide having a unit represented by the formula: These may have an inert substituent such as a methyl group, an alkoxyl group, or a halogen atom. (3) Aromatic polyamide imidazole formula

A polyamide imidazole having a unit represented by the formula [R: same as above]. These may have an inert substituent such as a methyl group, an alkoxyl group, or a halogen atom. (4) Aromatic polyimide formula

A polyimide having a unit represented by the formula: [R: same as above]. These may have an inert substituent such as a methyl group, an alkoxyl group, or a halogen atom. (5) Aromatic polyazole polybenzimidazole, polybenzoxazole, polybenzthiazole. These may have an inert substituent such as a methyl group or a halogen atom. (6) Polyquinazolinedione, polybenzoxazinone, polyquinazolone, polyquinoxaline. (7) Polythiazole, polyoxazole, polyoxadiazole, polyhydantoin, polyparabanic acid. 3 Precursor of nitrogen-containing polyheterocyclic compound

A polymer (precursor of polyamideimide) having a unit represented by the formula: [R: same as above]. (1) Aromatic polyhydrazide, aromatic polyurea Precursors obtained by copolymerizing these precursors with aromatic dicarboxylic acids such as isophthalic acid and terephthalic acid, benzophenone tetracarboxylic anhydride, pyromellitic anhydride, etc. You can also use your body. 4 Polyphenylene oxide, polyarylene oxide The above heat-resistant polymers are at least
It means a polymer having a softening point of 155°C or higher, preferably 250°C or higher, and whose physical properties do not change significantly even if it is used at a temperature of at least 155°C or higher in air for a long time. The aromatic polymer refers to a polymer in which a considerable portion of the main chain consists of aromatic rings, but such polymers are not limited to a particular structure or production method. Production of pulp-like particles When producing the pulp-like particles used in the present invention, a method can be applied in which an aromatic polymer solution in which potassium titanate fibers are mixed and dispersed is precipitated to form pulp-like particles. The potassium titanate fibers may be uniformly dispersed in advance in the solvent of the aromatic polymer when the aromatic polymer is dissolved, or they may be added to the solution obtained after dissolving the aromatic polymer. You may do so. Further, when obtaining an aromatic polymer by solution polymerization, it may be added before the start of polymerization or during the polymerization. The solvent for dissolving the aromatic polymer may be any inorganic or organic solvent as long as it does not substantially interact with the potassium titanate fibers and is water-soluble; for example, N-methyl- 2-pyrrolidone, N,N-dimethylformamide, N,N-
dimethylacetamide, dimethyl sulfoxide,
Organic solvents such as hexamethylphosphoramide and tetramethylurea are suitable. The organic solvents may be used in combination. Furthermore, a solvent system can be used in which the solubility of the aromatic polymer is increased by adding an inorganic salt such as lithium chloride or calcium chloride to the above-mentioned solvent. The concentration of the aromatic polymer in the solution varies depending on the type of polymer, the degree of polymerization of the polymer, and the amount of potassium titanate fiber added, but it is preferably approximately 2 to 15% by weight. In addition, the precipitating agent used in producing the pulp-like particles of the present invention is miscible with the solvent of the aromatic polymer, but is not compatible with a liquid or solution that is a non-solvent for the polymer. desirable. For example, when the solvent for the aromatic polymer is an organic solvent, water, glycerin, ethylene glycol, a mixture of glycerin and water, a mixture of water and an organic solvent, an aqueous solution of inorganic salts, etc., and when the solvent is an inorganic solvent, it is a water-inorganic solvent. Examples include mixtures of these, but aqueous ones are particularly preferred. Further, in producing the pulp-like particles used in the present invention, the precipitant is stirred at high speed to remove the solvent from the introduced solution and at the same time to produce a shearing action or a beating action. Any type of device can be used as long as it produces a sufficient shearing action or beating action, but it is preferable that it is equipped with stirring blades that can rotate at high speed. Either a tank type or a pipe agitation type may be used. Paper Making The pulp-like particles used in the present invention can produce excellent sheets by themselves, but by mixing them with other short fibers to make paper, paper-making properties are improved and sheets with better performance can be produced. Obtainable. It is preferable to make paper from pulp particles and short fibers by a wet process using a Fourdrinier or cylinder paper machine, as in the case of paper making from conventional wood pulp. Any heat-resistant short fiber can be used, but the fineness of the short fiber is 0.5 to 10 denier.
Preferably it is 1.0 to 5 deniers. The length of the short fibers is 1 to 30 mm, preferably 2 to 20 mm. 1
If it is shorter than mm, the mechanical properties of the obtained sheet will be poor, and if it is longer than 30 mm, it will be difficult to disperse the fibers during paper making. Examples of short fibers include the following: (1) Short fibers made of aromatic polyamide. The aromatic polyamide is the same as above. (2) Short fibers made of nitrogen-containing polyheterocyclic compounds. The nitrogen-containing polyheterocyclic compound is the same as above. (3) Short fibers made of a precursor of a nitrogen-containing polyheterocyclic compound. The precursor of the nitrogen-containing polyheterocyclic compound is the same as above. (4) Short fibers made of polyphenylene oxide and polyarylene oxide. (5) Short fibers made of aromatic polyester. As the aromatic polyester, (a) polyethylene-2,6-naphthalate and/or polyethylene-2,7-naphthalate. (b) A copolymerized polyester containing 85 mol% or more of ethylene-2,6-naphthalate units and/or ethylene-2,7-naphthalate units. In this case, a copolymerized polyester using an aromatic dicarboxylic acid as an acid component is preferably used as a copolymerization component. (c) 85 mol% or more of (i) polyethylene-2,6-naphthalate and/or polyethylene-2,7-naphthalate and (ii) ethylene-2,6-naphthalate and/or ethylene-2,7-naphthalate units Mixed polyester containing copolymerized polyester. (d) Polyethylene terephthalate (e) Copolymerized polyester containing 85 mol% or more of ethylene terephthalate units. In this case, a copolymerized polyester using an aromatic dicarboxylic acid as an acid component is preferably used as a copolymerization component of the copolymerized polyester. (F) (i) Polyethylene terephthalate and/or
or (ii) 85 mol% ethylene terephthalate units.
A mixed polyester containing a copolymerized polyester containing the above. (6) Short fibers made of inorganic compounds. Examples of short fibers made of inorganic compounds include inorganic fibers such as glass fibers, asbestos fibers, rock wool, mineral wool, silica fibers, bauxite fibers, kyanite fibers, boron-based fibers, and magnesia fibers, and whiskers such as alumina and silicon nitride. (7) Natural fibers As natural fibers, cellulose fibers, regenerated fibers, cellulose acetate fibers, etc. are preferable. It is also possible to use a mixture of two or more of these short fibers. When paper is made from pulp-like particles and short fibers in the present invention, the amount of pulp-like particles is 5 to 95% by weight, preferably 10 to 90% by weight based on the sheet. If the amount of pulpy particles is less than 5% by weight,
Physical properties such as dielectric breakdown voltage and strength and elongation deteriorate. Moreover, if the amount of pulp-like particles is more than 95% by weight, impregnating properties, elongation, folding durability, etc. will deteriorate. The wet sheet obtained as described above can be used as it is after drying, but it can be made into a better sheet by heating it under pressure using a means such as a hot press or a hot roll. . The temperature at which the pressure is applied varies somewhat depending on the type of pulp particles and short fibers, but a temperature of 50° C. or higher is suitable. If the temperature is lower than 50°C, the pressure bonding may be insufficient and a strong sheet may not be obtained. Also
At temperatures higher than 350°C, it tends to lose its flexibility. The pressurizing pressure varies somewhat depending on the type, crystallinity, degree of polymerization, etc. of the pulp particles and short fibers as well as the temperature, but it is preferably 400 Kg/cm ² or less. If it exceeds 400Kg/ ^cm2 , it will become film-like, especially at high temperatures.
This is not desirable because it loses suppleness. The present invention will be explained in detail with reference to Examples below. Unless otherwise specified, parts and percentages are based on weight. Example 1 Preparation of aromatic polymer solution 90 parts of polymetaphenylene isophthalamide powder having an intrinsic viscosity ηinh of 1.80 measured at 30°C at 0.5 g/100 ml in 95% sulfuric acid was mixed with N-methyl-2- A solution was obtained by dissolving in a solvent consisting of 910 parts of pyrrolidone and 40 parts of water. 90 parts of potassium titanate fibers (manufactured by Otsuka Chemicals) were mixed with this solution using a kneader to obtain a solution of polymetaphenylene isophthalamide in which potassium titanate fibers were dispersed. Preparation of precipitant 70 parts of water was added to 30 parts of N-methyl-2-pyrrolidone to prepare a precipitant. Manufacture of pulp-like particles Consists of a combination of a stator with bulges and a turbine blade-shaped rotor, and a precipitant,
The polymer solution was simultaneously fed at 0.5 kg/min and the precipitant at 20 kg/min into a pipe-stirred continuous precipitator equipped with a polymer solution supply port and a pulp particle slurry discharge port after precipitation to form a pulp-like particle slurry. It was taken out from the outlet. At this time, the temperature of the precipitant was adjusted to 35°C, and the temperature of the polymer solution was adjusted to 50°C. In addition, the rotation speed of the rotor was 9600 rpm. The obtained pulp particle slurry was kept at 35° C. and left for about 30 minutes, and then charged into a Nutstier vacuum filtration vessel and most of the precipitant was taken out as a liquid. (At this time, a 150-mesh stainless steel wire mesh was used as the filter material, but the liquid was transparent and almost no potassium titanate fibers were detected in the liquid. This indicates that the fibers were coated with polymetaphenylene isophthalamide. This is an example of what is happening. 〉 Then, using the same Nutstier type vacuum filtration device, it was thoroughly washed with ion-exchanged water. Creating a sheet This pulp-like particle 2.0g (solid content) and single fiber fineness
Paper was made from an aqueous dispersion containing 0.3 g of 1.5 denier aromatic polyamide fiber (Konex, manufactured by Teijin Co., Ltd.) cut to a length of 7 mm using a Tatsupi standard sheet machine. Water drained from the wire mesh well and the paper-making properties were good. A uniform sheet with no spots was obtained. After drying this sheet at 105℃,
Heat pressed at ℃, 200Kg/ ^cm2 to a thickness of approximately 95μ
got the paper. The performance of this paper is as shown in Table 1, and all were good.

[Table] Comparative Example 1 Example 1 was carried out using 1.0 g (solid content) of pulp-like particles obtained in exactly the same manner as in Example 1, except that potassium titanate fibers were not added to the solution of polymetaphenylene isophthalamide. When paper was made by dispersing 1.0 g of the same potassium titanate fiber used in Example 1 and 0.3 g of the same aromatic polyamide fiber used in Example 1 in water during paper making, from the paper making wire mesh,
Leakage of potassium titanate fibers was observed, and the yield of potassium titanate fibers was 80%. Further, the strength and elongation of the paper obtained by pressing the sheet at 290° C. and 200 kg/cm ² after drying was as shown below, which was not sufficient. Tensile strength 3.3Kg/mm ^2Tensile strength 4.0% Example 2 The same procedure as in Example 1 was carried out except that the amount of potassium titanate fibers added to the solution of polymetaphenylene isophthalamide was varied. Pulp-like particles were obtained. In both cases, the liquid was transparent during filtering and washing using the Nutstier vacuum filter, and there was almost no leakage of potassium titanate fibers. Next, 2.16 g (solid content) of the obtained pulp-like particles and the aromatic polyamide fiber used in Example 1 were added.
Paper was obtained from 0.54 g in the same manner as in Example 1.
The performance of these papers is shown in Table 2.

[Table] In Table 2, No. 1 had a satisfactory tensile strength, but the equilibrium moisture content was somewhat high. No.
5, when potassium titanate fiber was added to the solution of polymetaphenylene isophthalamide,
The fluidity of the solution was lost and pulp could not be produced. Example 3 Preparation of polymer solution A bisimide compound was prepared by condensation reaction of trimellitic anhydride and 4,4'-diaminodiphenylmethane in a molar ratio of 2:1 in N-methyl-2-pyrrolidone, and then the above-mentioned 2 moles of trimellitic anhydride and 3 moles of 4,4'-diphenylmethane diisocyanate were added per mole of 4,4'-diaminodiphenylmethane and reacted with a bisimide compound to form polyamideimide (N-methyl-2- Polyamideimide dissolved in N-methyl-2-pyrrolidone by making the logarithmic viscosity in pyrrolidone 0.75)
A solution containing 25% by weight was obtained. (Solution A) Separately, 190 parts of ion-exchanged water was added to 2350 parts of N-methyl-2-pyrrolidone, and then 225 parts of the potassium titanate fiber used in Example 1 was added, and then T.K.
The mixture was stirred for 30 minutes using a homomixer (manufactured by Tokushu Kika Kogyo) to obtain a liquid mixture consisting of N-methyl-2-pyrrolidone, water, and potassium titanate fibers. (Mixed solution B) Next, 900 parts of solution A was added to 2,765 parts of mixed solution B and stirred until uniform, to obtain a solution consisting of polyamideimide, N-methyl-2-pyrrolidone, water, and potassium titanate fibers. (Solution C) Preparation of precipitant 30 parts of water was added to 70 parts of N-methyl-2-pyrrolidone and stirred briefly to prepare a precipitant. Production of pulp particles Into the same precipitator as used in Example 1, solution C0.5 was added.
Kg/min and the precipitant were simultaneously supplied at a flow rate of 10 Kg/min, and the pulp particle slurry was taken out from the outlet. At this time, the temperature of the precipitant was 35℃, and the temperature of solution C was 30℃.
It was adjusted to The rotation speed of the rotor was 9600 rpm. Next, the obtained pulp particles were placed in a centrifuge to separate most of the precipitant as a liquid, and then ion-exchanged water was supplied to thoroughly wash the pulp particles. Almost no potassium fiber leakage was observed. Preparation of sheet Tatsupi was prepared from an aqueous dispersion containing 2.43 g (solid content) of the thus obtained pulp-like particles and 0.27 g of aromatic polyamide fiber (Konex manufactured by Teijin) cut into a length of 6 mm with a single filament fineness of 2 denier. When paper was made using a standard sheet machine, water drained well from the wire mesh, the papermaking properties were good, and a uniform sheet with no unevenness was obtained. This sheet was dried at 105°C and then hot pressed at 230°C and 200 kg/cm ² to obtain paper with a thickness of about 100 μm. The performance of this paper was as follows. Tensile strength 5.4Kg/mm ^2Tensile strength 6.0% Breakdown voltage 30KV/mm Example 4 Obtained in the same manner as in Example 1 except that the ratio of pulp particles and short fibers was varied. The performance of the paper is shown in Table 3.

[Table] Nos. 1 and 3 are examples in which the ratio of pulp particles to short fibers is outside the scope of the present invention. It didn't work. No. 3 is an example where there are too many pulp particles, and the elongation of the obtained sheet is low.
Moreover, the folding durability was also poor. No. 2 is an example of the present invention, and had good paper-making properties and paper performance without any problems. Example 5 90 parts of a powder of polymetaphenylene isophthalamide having a logarithmic viscosity ηinh of 1.83 measured at 30° C. at 0.5 g/100 ml in 95% sulfuric acid was mixed with N having a water content of 0.5%.
-Methyl-2-pyrrolidone (910 parts) to obtain a solution. 360 parts of the same potassium titanate fibers used in Example 1 were mixed with this solution to prepare a solution of polymetaphenylene isophthalamide in which potassium titanate fibers were dispersed. Thereafter, the same procedure as in Example 1 was carried out to obtain pulp-like particles in which the proportion of potassium titanate fibers in the pulp-like particles was 80%. 3 g (solid content) of this pulp-like particle and 27 g of kaolin fiber (Kaowool manufactured by Isolite Babkotsu Fireproofing Co., Ltd.) were placed in 2 parts of water in a household mixer and stirred vigorously for about 3 minutes. Then, after making paper using a Tatsupi standard sheet machine,
It was dried at 105°C to obtain a sheet with a thickness of about 8 mm. When this sheet was exposed to the flame of a burner, no change in dimensions was observed and the flame resistance was good. Also, 350
The thermal conductivity at °C was as small as 0.06 Kcal/m·hr·°C, which was a preferable value for use as a heat insulating material, for example. Example 6 2.5 g of pulp-like material obtained in Example 5 (solid content)
A sheet was obtained in the same manner as in Example 1 from and 0.2 g of the same short fibers used in Example 1. (However, without hot press treatment) The tensile strength was 1.6 Kg/mm ² and the elongation was 6.0%. Even after being treated at 270°C for one month, the tensile strength and elongation hardly changed and the heat resistance was good. Furthermore, when exposed to the flame of a burner, it was only slightly deformed and had good flame resistance. Example 7 Pulp-like particles 0.5 same as used in Example 2 No. 2
g and 1.9 g of glass fibers having a diameter of 10 μm and a length of 5 mm were placed in 1 part of water in a household mixer, stirred for about 1 minute, and then made into paper using a Tatsupi standard sheet machine. After drying at 105℃, 320℃, 10
Approximately 310μm in thickness and density by heat pressing under Kg/ ^cm2 conditions.
A sheet of 0.36 g/cm ² was obtained.

Claims (1)

[Scope of Claims] 1 (a) Consisting of potassium titanate fibers and a heat-resistant aromatic polymer, the potassium titanate fibers are covered and connected with the heat-resistant aromatic polymer. A sheet made by mixing 5 to 95% by weight of pulp-like particles and (2) 95 to 5% by weight of short fibers. 2. The sheet according to claim 1, wherein the aromatic polymer constituting the pulp particles is a wholly aromatic polyamide. 3. The sheet according to claim 2, wherein the aromatic polymer constituting the pulp-like particles mainly consists of metaphenylene isophthalamide structural units. 4. The sheet according to claims 1 to 3, wherein the amount of potassium titanate fibers is 10 to 85% by weight based on the entire pulp-like particles. 5. The sheet according to claims 1 to 4, wherein the short fibers are wholly aromatic polyamide fibers. 6. The sheet according to claim 5, wherein the wholly aromatic polyamide mainly consists of metaphenylene isophthalamide structural units. 7. The sheet according to claims 1 to 4, wherein the short fibers are inorganic fibers. 8. The sheet according to claim 7, wherein the inorganic fiber is glass fiber. 9. The sheet according to claim 7, wherein the inorganic fibers are asbestos fibers. 10. The sheet according to claim 7, wherein the inorganic fibers are ceramic fibers.