COATED TEXTILE FABRIC

Abstract: Textile fabric (10, 30) having a coating (20) thereon which imparts flame spread resistance and smoke suppressant properties to the fabric. The coating (20) comprises a film-forming polymer binder and an inorganic heat reflective filler material selected from the group consisting of natural and synthetic silicates and barites dispersed in and bound to the textile fabric by the film-forming polymer binder. A method of producing a pile carpet having such a coating is also provided.

Description: -/- COATED TEXTILE FABRIC Field and Background of the Invention This invention relates to textile fabrics, such as carpets and upholstery fabrics, which have both good flame spread resistance and low smoke generating properties. It has been widely recognized that carpets used as floor coverings in buildings and upholstery fabric should be resistant to the spread of a fire and should have relatively low smoke generating properties. Indeed, carpets and upholstery fabric are subject to various building codes and fire codes which define the permissible limits of flammability and smoke generation. For example, federal regulations have required that all carpets sold in the United States pass the Pill Test (DOC FFI-70) . This test measures the response of a carpet to a small incendiary source, a flaming methenamine pill. The test primarily measures the behavior of the floor covering during the early stages of the fire. The flooring radiant panel test (ASTM Standard Test Method E648) was developed to measure the flame spread or flame propagation properties of a floor covering system when exposed to a more fully developed fire. In particular, it measures the flame propagation properties of the floor covering under conditions which simulate the influence of a large fire source in the room. With respect to the limits of smoke generation, ASTM Standard Test Method E662 was developed to measure the amount of smoke produced during a fire and is informative in showing the magnitude of the smoke problem. Manufacturers of carpet have been quite active in developing approaches to improving the flammability properties or smoke suppressant properties of carpet. One of the approaches to flame retardancy which has been taken is incorporating flame retardant additives in the face fibers of the carpet, as described, for example, in U.S. Patent Nos. 4,012,546, 4,097,630 and 4,193,911. Another approach has been to apply flame retardant after treatments to the fibers, as described, for example, in U.S. Patent Nos. 4,173,671, 4,504,546, 4,610,905 and 4,618,522. Another approach has involved incorporating a flame retardant additive in the latex coating which binds the pile yarns to the primary backing as described, for example, in U.S. Patent Nos. 3,663,345 and 4,689,256. Exemplary flame retardant additives have included antimony oxide, antimony chloride, phosphates and borates of alkali metals, alkaline earth metals and aluminum hydrates. It has also been recognized that the smoke from a fire is often more hazardous and life threatening than the actual flames. Consequently, it is desirable that a carpet not only be resistant to flame spread, but that it also have low smoke generation properties. However, many of the materials which function effectively as flame retardants to suppress flame spread in a carpet are totally ineffective as a smoke suppressant, or may even result in the generation of higher levels of smoke. In particular, those flame retardants which operate to reduce combustion, such as by cooling the fire, may actually result in causing more smoke to be generated since they produce an incomplete combustion of the combustible materials. Thus, smoke suppressant compounds must also be added to the carpet or carpet coatings. Exemplary compounds utilized as smoke suppressants include mixtures of certain nickel, bismuth, zinc, copper, iron or molybdenum compounds as described in U.S. Patent Nos. 3,975,359, 4,055,537 and 4,143,030. The competing—and often mutually exclusive—considerations of providing good flame retardancy while also suppressing of smoke present a significant obstacle to producing a carpet possessing both good resistance to flame spread and low smoke generation. Many manufacturers in seeking to achieve both these properties have found it necessary to seek a compromise between these characteristics in selecting the various flame and smoke retardant additives and ingredients used in the carpet. The present invention advantageously improves both the flame spread resistant and also the smoke suppressant properties of a textile fabric. Summary of the Invention The present invention is a departure from conventional approaches to imparting flame resistance to a fabric. In accordance with the present invention, a textile material is provided with a coating which includes an inorganic filler material which functions as a flame blocker and a radiant energy reflector. The filler material upon exposure to heat or flame forms a heat reflective ceramic barrier or mantle which effectively reduces the amount of flame spread and also the amount of smoke. Specifically, the coating of the present invention comprises a film-forming polymer binder and a heat reflective filler material selected from the group consisting of natural and synthetic silicates. The filler material is dispersed in and bound to the fabric by the film-forming polymer binder. In a preferred embodiment, mica is used as the inorganic filler material and the film-forming polymer binder is derived from at least one monomer selected from the group consisting of acrylic, vinyl, chlorinated vinyl, styrene, butadiene and ethylene monomers and copolymers or blends thereof. When the invention is used with carpets, the coating is applied to the rear surface of the primary backing of the carpet. A secondary backing, such as a foamed or unfoamed polyvinylchloride layer, is bonded to the coated rear surface of the primary backing. When used with upholstery fabrics, the coating is applied to the rear surface of the fabric, and forms a flame retardant, smoke suppressant, heat reflective barrier for protecting underlying cushioning materials. Brief Description of the Drawings Some of the features and advantages of the invention having been stated, others will become apparent from the detailed description which follows, and from the accompanying drawings, in which— Figure 1 is an isometric view of a pile carpet with one corner thereof being broken open to reveal the interior construction; Figure 2 is an isometric view of the pile carpet after it has been subjected to a flame in accordance with a flame spread resistance test; Figure 3 is an enlarged cross-sectional view taken substantially along line 3-3 of Figure 1 of a portion of the carpet; Figure 4 is an enlarged cross-sectional view taken substantially along line 4-4 of Figure 2 of a portion of the carpet; Figure 5 is an isometric view of a portion of an upholstery fabric in accordance with the present invention; Figure 6 is an enlarged cross-sectional view of a portion of the upholstery fabric taken substantially along line 6-6 of Figure 5; and Figure 7 is a diagrammatic and schematic representation of the method of treating fabric according to the present invention. Detailed Description of the Invention The present invention will be described more fully hereinafter with reference to the accompanying drawings, in which preferred embodiments of the invention are shown. This invention can, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, applicants provide these embodiments so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. The present invention is especially applicable to textile fabrics such as pile carpets or upholstery fabrics which are of a laminate-type construction and have a built-in backing or cushioning layer beneath the outer textile surface. For example, a pile carpet construction, as shown in Figures 1 and 3 , typically comprises a primary backing 10, pile yarns 15 extending through the primary backing, a precoat layer 20 applied to the rear surface of the primary backing 10 of the carpet as a "tuftlock" coating and a secondary backing 25. The secondary backing may typically comprise a foamed or unfoamed polymer composition such as polyvinyl chloride, polyethylene or polyurethane. An upholstery fabric construction, as shown in Figure 5, comprises an outer upholstery layer 30 of a woven, knitted or nonwoven textile fabric bonded to an underlying foam or padding layer 35. In accordance with the present invention, a coating is provided which, in addition to its function as a precoat layer for use with pile carpet fabric or an adhesive layer for use with upholstery fabric also provides improved flame spread resistance and smoke suppressant properties to the textile fabric. The coating, in either latex or plastisol form, comprises a film-forming polymer binder and an inorganic material which forms a heat reflective ceramic barrier upon combustion which is dispersed in and bound to the fabric by the film- forming polymer binder. The amount of the heat reflective material in relation to the polymer binder is typically from about 25 to about 200 parts by weight per 100 parts of polymer binder. Exemplary film-forming polymer binders may be derived from at least one monomer selected from the group consisting of acrylic, vinyl, chlorinated vinyl, styrene, butadiene and ethylene monomers and copolymers or blends thereof. Particularly useful binders include polyvinylidene chloride and vinyl acetate ethylene. The inorganic heat-reflective material includes natural and synthetic silicates and barites. A preferred silicate is mica which is a general name for a group of hydrous potassium- aluminum silicate minerals which may contain Mg, Fe(II) , Mn, Li, Fe(III) and Ti as major or minor constituents. The mica also may have some impurities such as FeSO A which add to the flame retardant properties of the mica. Mica is characterized by a structure based on sheets of linked (SiAl)0 A tetrahedrons, the geometry of which accounts for the characteristic cleavage of the mica into sheets or platelets. Upon exposure of the textile side of the carpet by a radiant heat source such as a flame located close to the carpet, the inorganic filler material, and particularly mica, functions as a flame spread resistance agent by blocking the heat from the flame from the highly flammable secondary backing portion of the carpet. Ninety to ninety- five percent or more of the heat energy is reflected from the heat source. As illustrated in Figures 2 and 4, the inorganic filler material, when subjected to a flame, forms a charred ceramic barrier 12 characterized by a highly porous net-like appearance. This barrier 12 is disposed between the heat source above the textile fabric and the highly flammable secondary backing 25. As shown in Figure 4, very little of the secondary backing has been burned because the barrier 12 formed by combustion of the coating layer 20 has blocked the flame from reaching the secondary backing 25 which typically feeds the flame. Moreover, the ceramic barrier reduces the amount of smoke generated by serving to promote more complete combustion of the combustible vapors which are evolved from the backing 25. In this regard, the charred ceramic barrier 12 appears to function much like the mantle of a gas lantern. Any smoke or vapors that are evolved from the backing 25 pass through the small openings of the barrier and are burned. The coating may also advantageously include hydrated inorganic filler material such as calcium carbonate or aluminum trihydrate. The amount may be varied as desired depending upon the nature of the secondary backing and the degree of flame and smoke suppressing desired. Particularly good results are observed when the hydrated filler is used in amounts equal to the amounts of ceramic barrier forming inorganic filler material present. The coating may also include an intumescent material. The intumescent particles expand and swell when exposed to high heat, thus further reducing the amount of smoke escaping from the layers of the carpet that may be burning. Further, the particles, when exposed to high heat, release water that reduces the propensity of the carpet to flame. Exemplary intumescent compounds may include compounds having a polyhydric source of carbon such as starch or pentaerthritol in combination with a source of hydrochloric acid or phosphoric acid such as monoammonium phosphate. The coating is particularly effective for improving the flame spread resistance properties of the textile fabric. Flame spread resistance is measured in accordance with ASTM Standard Test Method E662 for Critical Radiant Flux of Floor- Covering Systems Using a Radiant Heat Energy Source. This test is designed to simulate a likely set of conditions which may lead to fire spread in a carpet system. The test method determines a critical radiant flux, measured in watts per square centimeter, and is a measurement of the lowest level of radiant energy necessary for a fire to continue to burn and spread. The actual test uses a horizontally mounted floor covering sample which is exposed to radiant energy from a gas-air fueled radiant panel mounted above one end of the sample at an angle of 30°. The radiant panel generates a radiant flux profile along the length of the sample ranging from a maximum of 1.1 watts/cm 2 immediately under the panel to approximately 0.1 watts/cm 2 at the end of the sample remote from the panel. A gas fired pilot burner is used to initiate the ignition on the floor covering sample immediately below the radiant panel and the test is continued until the flooring system ceases to burn. The distance the flooring system burns to extinguishment is converted to watts per square centimeter from a calibration graph. The result of the test is reported as the critical radiant flux. This is the minimum radiant energy a fire needs to sustain flame propagation in the flooring system. In this test, the lower the number, the greater is the tendency of the system to spread flame. Conversely, the higher the number, the more resistant the material is to flame propagation. Oak flooring has a critical radiant flux value of about 0.35 to 0.40 watts/cm 2 and carpet using conventional coatings has a critical radiant flux value of about 0.36 to 0.45 watts/cm 2 . The present invention provides a pronounced improvement in this property and carpet using the present coating has a critical radiant flux value of from about 0.50 to 0.70 watts/cm 2 . The coating is also an effective smoke suppressant. Smoke suppressant properties are measured using ASTM Standard Test Method E662 entitled "Specific Optical Density of Smoke Generated By Solid Materials." The test measures the specific optical density of smoke generated by the solid materials and measures the concentration of smoke. A lower value is desired. Carpet coated with conventional flame retardants have a smoke density value of about 360 to 460, whereas the coating of the present invention provides a smoke density value of from 260 to 350. The coatings are applied to various textile fabrics such as pile carpet or upholstery fabric. Referring to Figures 1 and 3, pile carpets comprise a primary backing 10 and pile yarns 15 extending from the primary backing to form pile tufts. In tufted carpets, the pile yarn 15 is inserted into the backing by tufting needles and to maintain the yarn tufts permanently in place in the backing a coating 20 such as that of the present invention is applied to the rear surface of the primary backing 10 to lock the tufts in place. The primary backing may be formed of natural fibers such as jute, or of synthetic fibers such as polypropylene, polyethylene, or polyester, for example. The pile carpet also typically includes a secondary backing 25 bonded to the primary backing 10 using the thermoplastic properties of the present coating. The secondary backings 25 may be formed of woven or nonwoven materials similar to those used as the primary backing. The secondary backing may be formed of natural fibers, such as jute or of synthetic fibers such as polypropylene, polyethylene or polyester. Alternatively, the secondary backing may comprise a foamed or unfoamed polymer sheet. Suitable polymer compositions include urethane polymers, polymers and copolymers of ethylene, propylene, isobutylene, and vinyl chloride. These compositions, however, are typically flammable and emit potentially dangerous smoke when burned. The upholstery fabric may be a sheet or film such as vinyl or synthetic leather, or a woven, nonwoven or knitted fabric, formed of natural fibers, synthetic fibers or blends thereof. Particularly desirable is a fabric construction which provides a pleasing hand to the upholstery layer and permits patterns and grains to be incorporated therein for aesthetic appeal. Referring to Figures 5 and 6, the upholstery fabric is shown as being used in a laminate form which includes an outer upholstery layer 30 and an inner foam layer 35 to provide cushioning and a rear fabric or scrim layer 40 which facilitates securement of the laminate to an underlying substrate. The inner foam layer 35 and the outer upholstery layer 30 can be bonded together using the coating layer 20 of the present invention. Suitable foam compositions for the foam layer 35 include urethane polymers, polymers and copolymers of ethylene, propylene, isobutylene, and vinyl chloride with urethane polymers being preferred. Referring to Figure 7, the first step of the method of producing a pile carpet having flame spread resistance and smoke suppressant properties comprises applying to the rear surface of the primary backing of the carpet and in contact with the pile yarns extending through the rear surface of the backing, an aqueous latex coating comprising a dispersion of a film-forming polymer binder and an inorganic heat-reflective material such as natural and synthetic silicates and barites. The rear surface of the backing is then heated to dry the coating and to bind the heat-reflective material to the pile yarns. Finally, the secondary backing is bonded to the primary backing. The improved flame spread resistance and smoke suppressant properties are particularly illustrated by the specific examples which follow. Example 1 A carpet coating was compounded having the following ingredients: Parts by Weight Water 50.46 Emulsion copolymer of 2-ethylhexyl acrylate and vinylidene chloride 251. .35 Hydrocarbon-based non-silicone emulsion defoamer 0. . 64 Anti-foam surfactant 0. . 61 Anionic dispersant 0. . 64 Sodium polyacrylate thickener 25 , . 00 Mica 83 , . 62 Alumina trihydrate 83 , . 62 The compounded coating had a pH of 5 and a viscosity at 20 rpm of 3000 cps. The coating was mixed in an electric drum mixer until all of the solid material was dispersed. The coating was then coated on sections of carpet made from different nylon 66 fibers designated as "A", "B" and "C" at approximate coating levels of 7 gm/m 2 (24 oz/sq yds) . A polyvinylchloride secondary backing was then applied to the back of the carpet. Example 2 A carpet coating was compounded having the following ingredients: Parts i by Weight Water 50. 00 Emulsion copolymer of vinyl acetate and ethylene 246. , 00 Hydrocarbon-based non-silicone emulsion defoamer 1. , 00 Anti-foam surfactant 1. , 61 Anionic dispersant 2 . . 00 Sodium polyacrylate thickener 25. .00 Mica 121. . 00 Alumina trihydrate 121 , . 00 The compound coating had a pH of 5.5 and a viscosity at 20 rpm of 3000 cps. The coating was then mixed and coated on sections of carpet made from nylon 66 fibers the same as in Example 1 at coating levels of 7 gm/m 2 (24 oz/sq yds) . A polyvinylchloride backing was then applied to the back of the carpet. Example 3 A carpet coating was compounded having the following ingredients: Parts by Weight Water 50.00 Emulsion copolymer of vinyl acetate and ethylene 246.00 Hydrocarbon-based non-silicone emulsion defoamer 1.00 Anti-foam surfactant 1.01 Anionic dispersant 2.00 Sodium polyacrylate thickener 25.00 Mica 121.00 The compounded coating had a pH of 5 and a viscosity at 20 rpm of 3000 cps. The coating was mixed and coated on sections of carpet made from nylon 66 fibers designated as "A" at approximate coating levels of 7 gm/m 2 (24 oz/sq yds) . A polyvinylchloride secondary backing was then applied to the back of the carpet. Example 4 A conventional coating without any mica was prepared having the following ingredients: Parts by Weight Emulsion copolymer of 2-ethylhexyl acrylate and vinylidene chloride 260, .00 Hydrocarbon-based non-silicon emulsion defoamer 2. .19 Anti-foam surfactant 0. .89 Ammonium hydroxide (28%) 0. .68 Sodium polylacrylate thickener 16, .45 Aluminum trihydrate 79, .80 Calcium carbonate 39, .90 The compound coating had a pH of 5.5 and a viscosity at 20 rpm of 3000 cps. The coating was then mixed and coated on sections of carpet made from nylon 66 fibers as in Example 1 at coating levels of 7 gm/m 2 (24 oz/sq yds) . A polyvinylchloride backing was then applied to the back of the carpet. The critical radiant flux and the smoke density of the coated carpet samples were measured using ASTM Methods E662 and E648 respectively. These results are summarized in Table 1 as follows: Table 1 Critical Smoke Example No. Fiber Tvpe Radiant Flux Densitv 1 A 0.59 349 B 0.51 349 C 0.69 317 2 A 0.49 286 B 0.57 272 C 0.55 275 3 A 1.09 380 4 (control) A 0.39 464 B 0.36 417 C 0.45 364 As is readily apparent, a textile fabric having a coating comprising a film-forming polymer binder and an inorganic filler material which forms a heat reflective barrier upon combustion and has improved flame spread resistance and smoke suppressant properties as compared to carpets having a conventional coating thereon. Of particular significance is that the fibers coated with the present coating and having a polyvinylchloride backing still exhibit acceptable smoke density value despite the fact that the polyvinylchloride secondary backing usually results in poor, unacceptable values because of the great amount of smoke polyvinylchloride polymers tend to give off upon combustion. While particular embodiments of the invention have been described, it will be understood, of course, that the invention is not limited thereto since modifications may be made by those skilled in the art, particularly in light of the foregoing teachings. It is, therefore, contemplated by the appended claims to cover any such modifications as incorporate those features which constitute the essential features of these improvements within the true spirit and scope of the invention.

Claims: .THAT WHICH IS CLAIMED IS: 1. A textile fabric characterized by flame spread resistance and smoke suppressant properties, said fabric comprising a fabric base and a coating on the fabric base comprising a film- forming polymer binder and an inorganic filler material which forms a heat reflective ceramic barrier upon combustion, said inorganic filler material being dispersed in and bound to the fabric base by said film-forming polymer binder. 2. The textile fabric as set forth in Claim 1 wherein the inorganic filler material is selected from the group consisting of natural and synthetic silicates and barites. 3. The textile fabric as set forth in Claim 1 wherein the inorganic filler material is mica. 4. The textile fabric as set forth in Claim 1 wherein said coating additionally comprises a hydrated inorganic filler material also dispersed in and bound to the textile fabric by said film- forming polymer binder. 5. The textile fabric as set forth in Claim 4 wherein said coating additionally comprises an intumescent material also dispersed in and bound to the textile fabric by said film-forming polymer binder. 6. The textile fabric as set forth in Claim 1 wherein said film-forming polymer binder is derived from at least one monomer selected from the group consisting of acrylic, vinyl, chlorinated vinyl, styrene, butadiene and ethylene monomers and copolymers or blends thereof. 7. The textile fabric as set forth in Claim 1 wherein the inorganic filler material of said coating is present in an amount ranging from about 25 to about 200 parts by weight per 100 parts of polymer binder. 8. The textile fabric as set forth in Claim 1 wherein said fabric base comprises an upholstery fabric having a front surface adapted to face outermost on an upholstered article and a rear surface on the opposite side thereof, and wherein said coating is carried by the rear surface of said fabric. 9. The textile fabric as set forth in Claim 1 wherein said fabric base comprises a pile carpet having a primary backing and pile yarns extending from the backing to form a pile surface on the face of the carpet, and wherein said coating is carried by the rear surface of said primary backing. 10. A textile fabric as set forth in Claim 9 wherein said pile carpet additionally comprises a secondary backing adhesively secured to the primary backing. 11. A textile fabric as set forth in Claim 10 wherein said secondary backing is a polyvinylchloride foam. 12. A textile fabric as set forth in Claim 1 wherein said coating on the fabric base is adhesively bonded to one surface of a foam layer to form a foam-fabric laminate. 13. An upholstery fabric laminate as set forth in Claim 12 wherein said laminate includes a scrim layer which facilitates securement of the laminate to an underlying substrate. 14. A method of producing a pile carpet as defined in Claim 9 having flame spread resistance comprising the steps of: (a) applying to the rear surface of the primary backing of a carpet and in contact with the pile yarns extending through the rear surface of the backing, an aqueous latex coating comprising a dispersion of a film-forming polymer binder and an inorganic heat reflective material selected from the group consisting of natural and synthetic silicates, barites, talcs and silicas; (b) heating the rear surface of the primary backing to dry the coating and to bind the inorganic heat reflective material to the pile yarns; and (c) bonding a secondary backing to the primary backing. 15. The method of Claim 14 wherein the amount of coating applied ranges from about 20 ounces per square yard to about 30 ounces per square yard.

Inventors: PRICE KENNETH TIMOTHY, ROBERTS RUTH CLAUDETTE, TOMPKINS STEPHEN RAY, PRICE, KENNETH, TIMOTHY, ROBERTS, RUTH, CLAUDETTE, TOMPKINS, STEPHEN, RAY
Applicants: COLLINS & AIKMAN CORP, COLLINS & AIKMAN CORPORATION
Application year: 1989
Main classification: D06N7
IPC codes: D06M11, D06M15, D06M23, D06N7