COATED CLOTH

Abstract: A coated cloth, wherein a composition containing a halogen-free base polymer, from 50 to 400 parts by weight of a material which is thermally decomposable to release water, and more than 3 parts by weight of powdery fibers based on l00 parts by weight of the base polymer, is coated on a cloth. The coated cloth is excellent in the abrasion resistance and flame retardant, as well as releasing less smoke.

Description: This invention concerns coated cloth for use in seats and linings of railroad vehicles and the like. Flame-retardant coated cloth for use in buildings, vehicles or the like have been prepared, for example, by coating a synthetic leather layer 1 mainly composed of polyvinyl chloride (hereinafter simply referred to as PVC) on a cloth layer 2, for example, as shown in Figure 2. However, since such conventional coated cloth having PVC synthetic leather bonded thereto contains chlorine (halogen) atoms in the molecular structure of PVC and such halogen compound is less combustible, the PVC blend used in the synthetic resin releases toxic gaseous hydrogen chloride upon combustion and also forms droplets of molten PVC upon combustion due to the low melt viscosity at high temperature. Accordingly, the PVC coated cloth in the prior art has provided a problem in view of life safety and security upon occurrence of fire accidents and, therefore, cannot satisfy the standards required for practical enforcement shown in Table 1. GB-A-2093875 discloses a flame retardant building material formed by mixing waste aluminium hydroxide in gel-like form with an organic fibrous material such as scrap paper, drying the mixture, and disintegrating the dried material into a fluff which is admixed and kneaded with an aqueous solution of a flame retardant, preferably an inorganic phosphate or a halogen-containing organic phosphorus compound. Such material may be used as a fluffy, low bulk density heat and sound insulator material, or it can be mixed with a coagulant and pressed to form insulation boards etc. AT-A-360130 discloses a thermally expandable sealing material formed on the basis of a fleece or cloth of glass or plastics as a carrier and containing, per 100 weight parts of expandable graphite, 10 to 30 weight parts of polychlorobutadiene, 1 to 40 weight parts of alkylphenol-formaldehyde resin, 1 to 3 weight parts of stabiliser, up to 30 weight parts of an inorganic fiber and up to 80 weight parts of aluminium hydroxide. The sealing material is for seams, joints, cavities etc. SUMMARY OF THE INVENTION The object of this invention is to provide coated cloth that neither releases toxic gases nor causes hot droplets upon occurence of fire accidents. According to the present invention, there is provided a coated cloth comprising a halogen-free, polymer-based blend coated on a cloth substrate, said blend containing a halogen-free base polymer, 50 to 400 parts by weight (per 100 parts by weight of the halogen-free base polymer) of a material which is thermally decomposable to release water, and at least 3 parts by weight (per 100 parts by weight of the halogen-free base polymer) of powdered fibers which have a higher hardness than that of the base polymer. The thermally decomposable material is preferably an inorganic material eg a hydroxide such as aluminium hydroxide [Al(OH)₃] or calcium hydroxide [Ca(OH)₂], or a hydrated salt such as CaCl₂.6H₂O or Na₂SO₃.7H₂O, or the like. The powdered fibers are typically ground or milled fibers of, for example, a halogen-free polymer such as a polyester, polyamide, phenolic or ethylene-vinyl acetate polymer, or of a metal or a ceramic. BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS These and other objects, as well as advantageous features of this invention will become apparent by reading the following description of a preferred embodiment according to this invention while referring to the accompanying drawing, wherein Figure 1 is a cross sectional view for the coated cloth according to this invention, and Figure 2 is a cross sectional view for a prior art coated cloth as discussed previously. DESCRIPTION OF THE PREFERRED EMBODIMENT. Figure 1 is a cross-sectional view illustrating one embodiment of this invention in which a coating 3 is provided on a cloth substrate 2. The properties required for the coated cloth include sufficient bonding strength and tensile strength for the coating 3 and the cloth substrate 2, and sufficient tensile strength and tear strength after stitching or the like, in addition to those set forth in Table l. The properties equal to those in the prior art can be provided by using conventional methods and selecting an appropriate cloth and method of bonding. Example The properties shown in Table 1 are determined by composition coated on the cloth substrate and they were tested at the blending ratio shown in Table 2. Explanation will be made to the contents of the experiment. Each of the blends (A - H) of the composition shown in Table 2 was sufficiently mixed on a 4 inch (10.16 cm) roll and coated by press bonding to a cloth, woven from polyamide fiber threads of 420 denier both for warps and wefts 25 threads per inch (per 2.54 cm) width, to the entire thickness of 0.6 mm to prepare coated cloth. The blend-coated cloths A - E and H incorporated with the vulcanizer were further maintained in an oven at 150°C for 60 min to apply vulcanization for the blends. Table 3 shows the result of the performance test in Table 1 and D, G and H pass the overall estimation. As can be estimated from the result, the blend-coated cloth containing more than 50 parts by weight of aluminum hydroxide based on 100 parts by weight of the base polymer is improved with the combustibility for the flame residual time and the propagation distance. However, if it is blended by more than 500 parts by weight, excess vapour is generated (in this case steam). The resistance to combustion can be improved by the incorporation of aluminum hydroxide which causes steam generation at high temperature. A similar effect can also be obtained by use of other hydroxides, for example, magnesium hydroxide. If a phenol resin is incorporated as the powdered fiber in an amount of at least 3 parts by weight per 100 parts by weight of the base polymer, the abrasion resistance can be improved in the case of acrylic rubber base polymers, and the abrasion resistance and dropping property during combustion can be improved in the case of ethylene-vinyl acetate resin type base polymers. It is considered that these improvements can be obtained because the powdered fibers present on the surface of the coating can protect the surface against friction. It is also considered that the dropping can be improved, because the powdered fibers tighten the structure of the coating composition. Accordingly, other powdered fibers having such function, for example, polyamide resin, polyester resin, metal and ceramic can also provide similar effect. For selecting the powdered fibers, it is necessary that those powdered fibers having higher hardness than the base polymer (hardness after the vulcanization, if it is vulcanized) should be selected. Table 4 shows the result of the abrasion test for the sheet of about 1 mm thickness prepared by the same procedures as the blending content for the test result. In the foregoing experiment, although acrylic rubber, natural rubber, SBR and ethylene-vinyl acetate resin have been used as the base polymer, abrasion resistance can be improved by using any of other base polymers so long as they are within the principle of this invention, and the base polymer can be selected while considering the degree of required performance and the cost. The base polymer may be natural rubber, styrene-butadiene rubber, nitrile-butadiene rubber, acrylic rubber, ethylene-propylene rubber, butyl rubber, silicone rubber ethylene-vinyl acetate resin, ethyle-vinyl acrylate resin or the like in view of the experiences in the past and the aforementioned experiments but they are no way restricted only thereto as described above. As has been described above, according to this invention, since a cloth substrate is coated with a blend not containing halogen elements and excellent in the abrasion resistance and combustion property, if fire accident should occur in vehicles or buildings installed with seats or the likes using the coated cloth according to this invention, the coated cloth do not propagate the fire, and neither releases toxic gas nor results in hot droplets. Accordingly, it can provide an advantageous effect of life safety and security and provide more extended working life than the prior art products due to the excellent abrasion resistance.

Claims: A coated cloth comprising a halogen-free, polymer-based blend coated on a cloth substrate, said blend containing a halogen-free base polymer, 50 to 400 parts by weight (per 100 parts by weight of the halogen-free base polymer) of a material which is thermally decomposable to release water, and at least 3 parts by weight (per 100 parts by weight of the halogen-free base polymer) of powdered fibers which have a higher hardness than that of the base polymer. A coated cloth as defined in claim 1, wherein the powdered fibers are at least one selected from the group consisting of phenol resin, polyamide resin, polyester resin, metal and ceramic powdered fibers. A coated cloth as defined in claim 2, wherein the powdered fibers are phenol resin powdered fibers. A coated cloth as defined in claim 1, 2 or 3, wherein the thermally decomposable material is a hydroxide or a hydrated salt. A coated cloth as defined in claim 4, wherein the hydroxide is aluminium hydroxide or magnesium hydroxide.

Inventors: FUKUSHIMA, SABURO, INAGAKI, YUTAKA, YAMADA, SUSUMU
Applicants: KAWASAKI JUKOGYO KABUSHIKI KAISHA
Application year: 1987
Main classification: D06N7
IPC codes: D06M11, D06M23, D06N7, D06M15