JPH0458379B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD The present invention relates to a method for producing a heat-resistant sheet with excellent bending resistance.More specifically, the present invention relates to a method for manufacturing a heat-resistant sheet with excellent bending resistance. The present invention relates to a method of manufacturing a plastic sheet. Conventional technology Conventionally, polyester fiber (melting point 255-260℃),
A thermoplastic resin such as polyvinyl chloride (PVC) (heat-resistant temperature 66-79°C), polyurethane (heat-resistant temperature 90-120°C), acrylic is added to a fibrous base fabric made of polyamide fiber (melting point 215-260°C). Resin (heat-resistant temperature 60-88℃), polyethylene (heat-resistant temperature 80-120℃)
Sheet materials obtained by coating polypropylene (heat resistant temperature: 120 to 160° C.), polyamide (heat resistant temperature: 80 to 150° C.), or polyester (heat resistant temperature: about 120° C.) are known. In this case, since the melting point of the fibrous base fabric is relatively low, the coating material that covers it must be able to be coated at a processing temperature that the fibrous base fabric can withstand. As for the coating material, as mentioned above, a resin having relatively low heat resistance is used. However, in recent years, fiber sheet materials have been increasingly used for firefighter's clothing, heat-resistant clothing, building materials, etc., and in order to maintain safety from fires, burns, and other thermal disasters, fiber sheet materials have become more and more popular. The demand for fuel, etc. is increasing. Therefore, the development of heat-resistant sheet materials is strongly desired. In response to the above-mentioned request, Japanese Patent Application Laid-Open No. 58-120677
and No. 58-127757 propose a high-temperature insulation paint and a fire-resistant insulation film containing an alkali titanate and a silicone resin.
Nos. 58-130183, 58-199791, and 59-35938 disclose materials obtained by forming a coating layer containing a silicone resin and an alkali titanate on the surface of an inorganic core material, such as a glass base fabric or asbestos paper. A fire resistant sheet is disclosed. Furthermore, JP-A-59-26987 and JP-A-59-36157 disclose a heat-resistant composition in which a polyolkanophosphonitrile compound is mixed with a silicone resin or an alkyl silicate, and a method for coating an inorganic core material with this heat-resistant composition. This is disclosed. Heat-resistant sheets using these inorganic fiber base fabrics had excellent fire-resistance, heat-insulating properties, stain resistance, and weather resistance, but their large weight (fabric weight) made them inconvenient to use and handle. Moreover, since it is difficult to sew and has low bending resistance, it tends to break during use, and it also tends to tear at perforations. Furthermore, in JP-A No. 59-14950, PTFE is used in the base fabric.
(polytetrafluoroethylene) resin coating,
It has been disclosed that this method is baked and fixed at a high temperature of 480°C, but when this method is applied to an organic fiber base fabric, the base fabric deteriorates due to the above-mentioned high temperature treatment, and the mechanical strength of the entire heat-resistant sheet obtained decreases. This causes the disadvantage that the bending strength becomes low. Problems to be Solved by the Invention The present invention has satisfactory heat resistance, is easy to sew, has good bending resistance, and has excellent bending resistance that is difficult to cut from perforations. The present invention aims to provide a method for manufacturing sheets. Means for Solving the Problems The method for producing a heat-resistant sheet with excellent bending resistance of the present invention includes at least one base fabric containing as a main component a heat-resistant organic synthetic fiber having a melting point of 300° C. or higher or a thermal decomposition point. A heat-resistant coating containing a fluorine-containing resin having a melting point of 280°C or lower, and 1 to 200 parts by weight of alkali titanate per 100 parts by weight of the fluorine-containing resin, and heat-treated at a temperature of 400°C or lower. It is characterized by forming a layer. Function The heat-resistant fiber constituting the base fabric used in the method of the present invention is selected from heat-resistant organic synthetic fibers having a melting point of 300°C or higher or a thermal decomposition point. Polymers that form such high melting point or high decomposition point fibers include those shown in Table 1.

【table】

【table】

【table】

[Table] Among the heat-resistant polymers shown in Table 1,
Aromatic polyamides, particularly polymetaphenylene isophthalamide and polyparaphenylene terephthalamide, are commonly used, and other para-aramid fibers such as "HM-50" manufactured by Teijin Ltd. can also be used. Aromatic polyamides useful in such fibers also have at least 50 mole percent of the following formulas () and (): -( _Ar1 -CONH-) ()-( _Ar1- CONH-Ar2 _- NHCO-) () [In the above formula, Ar ₁ and Ar ₂ represent divalent aromatic groups, and these may be the same or different.] It is preferable to have it as a repeating unit.
In the above formulas () and (), Ar ₁ and Ao ₂
The divalent aromatic group represented by the following formula,

【formula】

【formula】

【formula】

【formula】

【formula】

【formula】

【formula】

[Formula] O call

[Formula] [In the above formula, A is -O-, -S-, -SO-, _-SO2
-, -CO-, _-CH2- , or -C( _CH3 ) _2- ] is preferably selected from the group of aromatic residues represented by the following. These aromatic residues may contain inert substituents such as halogens, alkyl groups, nitro groups, and the like. Generally, the aromatic polyamide has the following formula: More preferred are those having the repeating unit represented by as a main component. In the method of the present invention, a base fabric formed mainly of heat-resistant organic synthetic fibers, especially aromatic polyamide fibers as described above, is heated at a temperature of 400°C or less for a coating layer containing a fluorine-containing resin having a melting point of 280°C or lower.
℃ or below), there is little decrease in mechanical strength.
A heat-resistant sheet with excellent bending resistance can be obtained. In addition to the above, heat-resistant organic synthetic fibers include those with a melting point or decomposition point of 300℃ or less,
Fluorine fibers and other fibers can also be used. Fibers having a melting point or decomposition point below 300° C. can also be incorporated into the base fabric to promote adhesion and other performance with the heat-resistant coating layer. However, the base fabric contains 50% heat-resistant organic synthetic fiber.
It is preferable that the content is 60% by weight or more.
It is further preferable that the content is more than 100%. These heat-resistant organic synthetic fibers may be in any form such as short fiber spun yarn, long fiber yarn, split yarn, or tape yarn, and the base fabric may be woven, knitted, nonwoven, or a composite fabric of these. It can be either. However, in consideration of the strength of the sewn portion and the bending resistance, the base fabric is preferably a woven fabric or a knitted fabric, and a woven fabric is more preferable. Also,
The fibers are preferably in the form of long fibers (filaments) that have little elongation under stress, and are preferably in the form of a plain woven fabric. However, there are no particular limitations on the weaving structure or its form. The heat-resistant organic synthetic fiber base fabric used in the method of the present invention is useful for maintaining the mechanical strength of the resulting heat-resistant sheet at a high level. In the method of the present invention, the heat-resistant coating layer formed on at least one surface of the base fabric comprises a fluorine-containing resin having a melting point of 280°C or lower and 1 to 200 parts by weight of titanium per 100 parts by weight of the fluorine-containing resin. This includes acids and alkalis. The fluorine-containing resin used in the method of the present invention is 280
℃ or lower, such as tetrafluoroethylene-hexafluoropropylene copolymer (mp 275℃), polychlorotrifluoroethylene (mp 215℃), polyvinylidene fluoride (mp 165-180℃), polyvinyl fluoride The polymer contains at least one selected from chloride (mp 200 to 210°C), chlorotrifluoroethylene-ethylene copolymer (mp 245°C), and the like. A mixture of a fluorine-containing resin with a melting point of 280°C or less and an alkali titanate, such as the above-mentioned fluorine-containing resin, is particularly effective for forming a heat-resistant coating layer on a heat-resistant organic synthetic fiber base fabric. be. That is, when this blend is applied to a base fabric made of heat-resistant organic synthetic fibers, it exhibits particularly excellent heat-resistant effects without impairing its mechanical strength. Although these fluorine-containing resins have extremely good weather resistance, ultraviolet absorbers may be blended into these resins for the purpose of protecting the base fabric. Also,
Of course, colorants and other performance-imparting agents may be added. The coating layer made of these resins may be microporous or may have continuous or discontinuous cells. The alkali titanate used in the method of the present invention has the general formula M ₂ O・nTiO ₂・mH ₂ O (where M is Li,
It represents an alkali metal such as Na or K, n represents a positive real number of 8 or less, and m represents 0 or a positive real number of 4 or less. ) is a well-known compound represented by
More specifically, Li ₄ TiO ₄ Li ₂ TiO ₃ (0<n<1,
Alkali titanates with a salt-type structure represented by m=0), Na ₂ Ti ₇ O ₁₅ , K ₂ Ti ₆ O ₁₅・K ₂ Ti ₈ O ₁₇ (n<
6, m=0), etc., which has a tunnel structure and is an alkali titanate. Among these, the general formula
Potassium hexatitanate and its hydrate represented by K ₂ O, 6TiO ₂ mH ₂ O (in the formula, m is the same as above),
This is suitable because it greatly improves the fire resistance and heat insulation properties of the final object. Alkali titanates, not just potassium hexatitanate, are generally powder or fibrous microcrystals, but among these, those with a fiber length of 5 μm or more,
An aspect ratio of 20 or more, especially 100 or more brings about favorable results in improving the strength of a heat-resistant sheet with excellent flexibility in the method of the present invention. In addition, fibrous potassium titanate has a high specific heat and excellent heat insulation performance, and is particularly preferable for realizing the performance of a heat-resistant sheet. Furthermore, the heat-resistant coating layer formed in the method of the present invention may contain a high refractive index inorganic compound or a heat-absorbing inorganic compound. High refractive index inorganic compounds have excellent shielding performance against radiant heat, and when endothermic inorganic compounds come into direct contact with slag during welding or fusing, they are heated at this contact surface, and an endothermic reaction occurs during decomposition, lowering the temperature of the slag. lower. Therefore, the above-mentioned inorganic compound can suppress the collapse and penetration failure of the heat-resistant coating layer, and can further protect the sheet base material. The high refractive index inorganic compound useful in the method of the present invention may have a refractive index of 1.5 or more, but those with a specific gravity of 2.8 or more are particularly suitable, and examples thereof include the following. 1) Dolomite (dolomite, specific gravity 2.8-2.9, refractive index 1.50-1.68) Magnesite (rhizoite, specific gravity 3.0-3.1, refractive index 1.51-1.72) Aragonite (rhizoite, specific gravity 2.9-3.0, refractive index 1.53-1.68) ) Avatite (Apatite specific gravity 3.1-3.2, refractive index 1.53-1.54) Spinel (Spinel specific gravity 3.5-3.6, refractive index 1.72-1.73) Corundum (Spinel specific gravity 3.9-4.0, refractive index 1.76-1.77) Zircon (Spinel specific gravity 3.9-4.0, refractive index 1.76-1.77) Powder of crushed natural or synthetic minerals such as crystal (specific gravity 3.90-4.10, refractive index 1.79-1.81), silicon carbide (spinel specific gravity 3.17-3.19, refractive index 2.65-2.69). 2) molten phosphorus obtained as a frit or high refractive glass or as a solid solution of phosphate rock and serpentine;
Other similar solid solution fine powders or granules, fibrous materials, foams, etc. In addition, endothermic inorganic compounds include calcined gypsum, alum, calcium carbonate, aluminum hydroxide, hydrosalcite-based aluminum silicate, etc., crystal water releasing type, carbon dioxide gas releasing type, decomposition endothermic type, phase change type, etc. Examples include type inorganic compounds. By mixing and dispersing fibrous alkali titanate and, if necessary, a high refractive index inorganic compound and/or an endothermic inorganic compound in a fluorine-containing resin, a coating mixture for producing a heat-resistant sheet with excellent bending resistance can be obtained. can get. All known means can be used to prepare the mixed dispersion. In addition, the above coating mixture contains dispersants and defoamers to homogeneously disperse each component, colorants to adjust color and mechanical strength, resin powder, flame retardants, metal powder, etc. Various fillers can be freely mixed. Incidentally, it is preferable to mix metal powder such as copper powder, nickel powder, brass powder, aluminum powder, etc. from the viewpoint of improving the surface heat reflection effect and the penetration suppressing effect. In the method of the present invention, the heat-resistant coating layer is formed on the surface of the base fabric by applying a coating mixture to the surface of the base fabric by a coating method such as spray coating, brush coating, roll coating, etc. to form the coating layer. A method of forming a coating mixture and subjecting it to heat treatment at a temperature of 400℃ or less, a method of molding a coating mixture and attaching the obtained film to the surface of a base fabric at a temperature of 400℃ or less, or a method of coating a base fabric. immersed in a mixture for impregnation,
There are methods such as applying heat treatment at 400°C or less. A heat-resistant sheet with excellent bending resistance can be produced by the method of the present invention, for example, as follows. That is, after adding appropriate curing accelerators and additives to a mixture of a fluorine-containing resin, an alkali titanate, and, if necessary, a high refractive index inorganic compound and/or an endothermic inorganic compound, toluene, xylene,
An organic solvent such as trichloride is added to make a dispersion with an appropriate concentration, and this dispersion is coated by a well-known coating method such as dipping, spraying, roll coating, reverse roll coating, or knife coating. Apply to one or both sides of the base fabric, and apply this coating layer to 400%
℃ or less, preferably 370℃ or less, more preferably
It is integrally fixed to the base fabric by heat treatment at a temperature of 250 to 350°C for 1 to 30 minutes. In particular, since the melting point of the fluorine-containing resin is 280°C or lower, the heat treatment temperature can be set relatively low, which reduces the strength of the heat-resistant organic synthetic fiber and improves the bending resistance of the resulting heat-resistant sheet. It can give excellent results. The blending ratio of fluorine-containing resin, alkali titanate, high refractive index inorganic compound, and/or endothermic inorganic compound, etc. varies depending on the type and particle size of the fluorine-containing resin and inorganic compound used, but in general, too little fluorine-containing resin As a result of the insufficient strength of the coating layer, when the obtained heat-resistant sheet is used as a fire-resistant heat insulating sheet, there are defects such as cracks in the coating layer or peeling of the coating layer from the base fabric. If there is too much resin contained, heat resistance will decrease. Therefore, in the method of the present invention, the amount of alkali titanate blended with respect to 100 parts by weight of the fluorine-containing resin (hereinafter "parts by weight" is abbreviated as "parts") is 1 to 200 parts, preferably 30 to 100 parts, and If high refractive index inorganic compounds and/or endothermic inorganic compounds are added to these, the amount shall be limited to 400 parts and 1/4 of the same weight.
Although it can be blended in place of an alkali titanate equivalent to up to 100 parts by weight, a range of 10 to 300 parts is usually preferred. Incidentally, part or all of these high refractive index inorganic compounds and endothermic inorganic compounds can be replaced with commonly used inorganic pigments, inorganic bulking fillers, inorganic powders that impart flame retardancy, etc. The amount used is preferably 400 parts or less, more preferably 300 parts or less per 100 parts of the fluorine-containing resin. In the method of the present invention, the thickness of the heat-resistant sheet with excellent bending resistance is preferably 0.02 mm or more, and more preferably within the range of 0.05 to 2.0 mm. In order to improve the adhesion and durability between the base fabric and the coating layer, an adhesive substance may be interposed between the two. In this case, there is no need to make the layer thicker than to improve adhesive strength. Adhesive substances are not used for film formation; therefore substances known as adhesives can be used. For example, acrylates containing amino groups, imino groups, ethyleneimine residues, alkylene diamine residues, acrylates containing aziridinyl groups, amino ester-modified vinyl polymers, aromatic epoxy adhesives, amino nitrogen-containing methacrylate polymers, etc. An adhesive may also be used. Further, resins or RFL modified substances that are the same as the polymer constituting the fiber base fabric, such as polyamideimide, polyimide, etc., can also be arbitrarily selected. In the method of the present invention, the heat-resistant coating layer may be formed only on one side of the base fabric, but it may be formed on both sides to compensate for the low weather resistance of the base fabric, depending on the usage situation. Double-sided formation may be an essential condition. Depending on the performance required for the sheet, the other side may be made of natural rubber, neoprene rubber, chloroprene rubber, silicone rubber, hypalon, etc.
Other synthetic rubber or PVC resin, ethylene-
Vinyl acetate copolymer (EVA) resin, acrylic resin, silicone resin, urethane resin, polyester resin and other synthetic resins can also be used. In this case, it is more preferable that these resins are flame retardant. The thickness of the coating layer is 5-2000μm, especially 10-1500μm
It is preferable that Example 1 and Comparative Example 1 In Example 1, an aromatic polyamide fiber (trademark: Konex, manufactured by Teijin Ltd.) spun yarn fabric having the following structure was used as the base fabric. Structure: Plain weave Warp: 30S/1, 60 pieces/25.4mm Weft: 30S/1, 54 pieces/25.4mm Weight: 90g/ ^m2 Tensile strength (average in both weft and warp directions): 66Kg/3cm FEP ( Tetrafluoroethylene-hexafluoropropylene copolymer, m.
p.275℃) 60 parts by weight of potassium titanate (trademark: Teismo D, manufactured by Otsuka Chemical Co., Ltd.) was mixed with 100 parts by weight of a 50% aqueous dispersion, and a small amount of water-soluble acrylic resin (thickener) was added to this. A coating solution having a viscosity of 1200 cps was prepared. The base fabric is dipped into the composition and squeezed, dried at a temperature of 250°C, and then dried at a temperature of 350°C for 30 minutes.
A heat-resistant coating layer was formed by processing for a minute. The thickness of this heat-resistant coating layer was approximately 150 μm on both surfaces. In Comparative Example 1, the same operation as above was repeated. However, potassium titanate was not used. The obtained sheet was subjected to the fire resistance and insulation test described in JP-A-58-130183. The evaluation criteria for fire resistance and heat insulation properties at this time were as follows. Class A: When cutting a 9mm thick spark-generating steel plate,
There shall be no through-holes that are harmful to the sparks that cause ignition and fire prevention. Class B: When cutting a 4.5mm thick spark-generating steel plate,
There shall be no through-holes that are harmful to sparks and cause fire prevention. Class C: When cutting a 3.2mm thick spark-generating steel plate,
There shall be no through-holes that are harmful to sparks and cause fire prevention. Class D: When cutting a 3.2mm thick spark-generating steel plate,
Penetration holes that are harmful to fire safety occur. Class E: When cutting a 3.2mm thick spark-generating steel plate,
Inflammation. The heat-resistant and heat-insulating properties of the heat-resistant sheet of Example 1 were Class B, while the heat-resistant and heat-insulating properties of the sheet of Comparative Example 1 were Class D. Commercially available asbestos paper (Class 3A) was Class E. That is, the heat-resistant sheet with excellent bending resistance produced by the method of the present invention exhibited extremely excellent fire-resistant and heat-insulating properties. In addition, the heat-resistant sheet of Example 1 was JIS P8115
(1976), ``Test method for folding durability using an MIT type tester for paper and paperboard'', it did not break even after being bent 10,000 times, and showed almost infinite folding strength. Comparative Example 2 A heat-resistant sheet was produced in the same manner as in Example 1. However, a glass fiber fabric having the following structure was used as the base fabric. Structure: Turkish satin weave Warp: DE 150 1/2 3.3S 51 threads/25.4mm Weft: Same as above 51 threads/25.4mm Weight: 290 g/m ² Also, as a coating composition, the following composition: Component amount (parts by weight) A mixture of 50% aqueous dispersion of tetrafluoroethylene-hexafluoropropylene copolymer (FEP), 100 water-soluble acrylic resin (thickener), 0.65 potassium titanate (trademark: Teismo D, manufactured by Otsuka Chemical Co., Ltd.) and 60 was prepared. . The viscosity of this mixture is approximately 900
It was centipoise hot. The resulting heat-resistant sheet had a fire-resistant and heat-insulating property of Class A, but its folding strength was only about 1,000 to 2,000 times of bending, which was extremely unsatisfactory. Example 3 A heat-resistant sheet was created in the same manner as in Example 1. However, the spun yarn used for the base fabric was a blended yarn (30S) of 50% by weight Cornex fiber and 50% by weight polyethylene terephthalate fiber. The resulting heat-resistant sheet had a fire-insulating property of class C and a folding strength that could withstand bending more than 10,000 times. Comparative Example 3 A heat-resistant sheet was produced in the same manner as in Example 1. However, the heating temperature of the coating layer was 450°C. In the obtained heat-resistant sheet, the fibers constituting the base fabric were hardened and had a plate-like feel, and the folding strength was about 4,000 to 5,000 times. Effects of the Invention In the method of the present invention, a fabric made of heat-resistant organic synthetic fibers having a melting point or thermal decomposition point of 300°C or higher is used as the base fabric, and the heat-resistant coating layer is
Formed by using a fluorine-containing resin having a melting point of ℃ or less and 1 to 200 parts by weight of alkali titanate per 100 parts by weight of this fluorine-containing resin, and at a heat treatment temperature of 400 ℃ or less. As a result, a heat-resistant sheet having both extremely excellent fire-resistant and heat-insulating properties and folding strength can be obtained. Therefore, the heat-resistant sheet with excellent bending resistance obtained by the method of the present invention can be suitably used in applications that are subjected to repeated bending at high temperatures, severe vibrations, and flapping (for example, fire-resistant clothing, opening/closing curtains).

Claims (1)

[Scope of Claims] 1. A fluorine-containing resin having a melting point of 280°C or less, and a fluorine-containing resin having a melting point of 280°C or less, and the Contains 1 to 200 parts by weight of alkali titanate per 100 parts by weight of fluorine-containing resin,
A method for producing a heat-resistant sheet with excellent bending resistance, characterized by forming a heat-resistant coating layer that is heat-treated at a temperature of 400°C or less. 2. The method according to claim 1, wherein the heat-resistant organic synthetic fiber is an aromatic polyamide fiber. 3. The fluorine-containing resin is at least one selected from tetrafluoroethylene-hexafluoropropylene copolymer, polychlorotrifluoroethylene, polyvinylidene fluoride, polyvinyl fluoride, and chlorotrifluoroethylene-ethylene copolymer. A method according to claim 1, comprising: 4. The method according to claim 1, wherein the alkali titanate is potassium hexatitanate or a hydrate thereof. 5. The method according to claim 1, wherein the heating temperature is 370°C or less.