US3847719A

US3847719A - Tufted carpet with gas-expandable pile and method

Info

Publication number: US3847719A
Authority: US
Inventors: R Crowley
Original assignee: Individual
Current assignee: Individual
Priority date: 1971-03-17
Filing date: 1972-12-26
Publication date: 1974-11-12
Anticipated expiration: 1991-11-12

Abstract

A tufted carpet and the method of preparing the same, which carpet comprises a backing sheet and a plurality of expanded cellular polymeric fibers secured to the backing sheet, the fibers providing a fibrous face surface, the fibers from the backing sheet secured thereto by the contact and compression of at least a part of the outer surfaces of the cellular polymeric fibers against the material of the backing sheet. The fibers may be expanded within the backing sheet or on either or both sides thereof. The method of preparing such a cellular tufted carpet comprises tufting gas-expandable fibers through a backing sheet, and, thereafter, heating the face, back, or both surfaces of the tufted backing sheet to a temperature sufficient to decompose the blowing agent in the gas-expandable fibers and to expand the fibers, thereby locking the fibers into the backing sheet.

Description

1 1 TUFTED CARPET WITH GAS-EXPANDABLE PILE AND METHOD [76] Inventor: Richard P. Crowley, 23 Salem Road, Wellesley Hills, Mass. 02110 [22] Filed: Dec. 26, 1972 [21] Appl. N0.: 317,923

Related US. Application Data [63] Continuation-impart of Ser. No. 125,335, March 17, I971, abandoned, which is a continuation-in-part of Ser. No. 25,275, April 12, 1970, Pat. No. 3,694,873, which is a continuation-in-part of Ser. No. 872,498, Oct. 30, 1969, Pat. No. 3,686,046.

[56] References Cited UNITED STATES PATENTS 3,778,330 12/1973 Shorrock 161/62 PREPARE GAS EXPANDABLE POLYMER FIBERS e.g. BY EXTRUSION TUFT FIBERS THROUGH A BACKING SHEET AT TEMPERATURE BELOW EXPANSION TEMPERATURE OF FIBERS HEAT THE FIBERS TUFTED THROUGH THE BACKING SHEET ON LEAST ONE SURFACE TO ATEMPERATURE TO EXPAND FIBER DIAMETER Nov. 12, 1974 Primary Examiner-Marion E. McCamish [57] ABSTRACT 'A tufted carpet and the method of preparing the same,

which carpet comprises a backing sheet and a plurality of expanded cellular polymeric fibers secured to the backing sheet, the fibers providing a fibrous face surface, the fibers from the backing sheet secured thereto by the contact and compression of at least a part of the outer surfaces of the cellular polymeric fibers against the material of the backing sheet. The fibers may be expanded within the backing sheet or on either or both sides thereof. The method of preparing such a cellular tufted carpet comprises tufting gasexpandable fibers through a backing sheet, and, thercafter, heating the face, back, or both surfaces of the tufted backing sheet to a temperature sufficient to decompose the blowing agent in the gas-expandable fibers and to expand the fibers, thereby locking the fibers into the backing sheet.

23 Claims, 5 Drawing Figures v TUFTED CARPET WITH GAS-EXPANDABLE PILE AND METHOD REFERENCE TO PRIOR APPLICATIONS This application is a continuation-in-part of US. application Ser. No. 125,335, filed Mar. 17, 1971, (now abandoned) which application is a continuation-in-part application of US. Ser. No. 25,275, filed Apr. 12, 1970 (now U.S. Pat. No. 3,694,873), which application was a continuation-in-part of US. Ser. No. 872,498, filed Oct. 30, 1969 (now U.S. Pat. No. 3,686,046),

BACKGROUND OF THE INVENTION Many fabrics,such as tufted carpets, are typically prepared by tufting, which includes a needle-punching or otherwise forcing or working a fibrous material into and/or through a sheet backing material, such as a jute fabric or more recently a flexible nonwoven polymeric fibrous sheet, such as a nonwoven polypropylene resin sheet. Such tufted materialsmay be employed as wall covering, personal clothing, such as coats and inner lining of garments, carpet and the like. Typically, to date the fibers tufted through thebacking sheet are secured to the backing material through the use of various adhesives applied to the back surface of the backing material after tufting. Adhesives, such as latices or vinyl, urethane resins or other polymeric materials, both natural and synthetic compositions, are coated on the back of the backing material afterthe tufting operation, and, thereafter, hardened, such as by curing, heating, cross-linking or otherwise, in order to secure the fibers to the backing material; that is, to increase tuft lock of the fibers to the material.

SUMMARY OF THE INVENTION.

My invention concerns new and improved fibrous products, and in particular,tufted carpets and the like wherein fibers are secured to a backing. sheet material. In particular, my invention relates to the use of synthetic polymeric gas-expandable fibers to prepare a tufted carpet wherein the fibers are secured to the backing sheet and locked into the backing sheet through the subsequentexpansion of the diameter of the fibers. My invention includes. tufted carpets wherein the fibers of thebase surface may be cellular or noncellular wherein thefibers are locked securely to the backing sheet material without theemployment of adhesives, though adhesives may be employed for additional tuft lock if required or necessary.

My invention includes providing a polymer composition which may include a resin,'such as a thermoplastic resin, such as a C -C olefinic resin, a blowing agent in an amount sufficient to expand the resin to the desired cellular density, and optionally, an additive to reduce the flow or melt viscosity of the resin to the desired temperature, as well as other additives, so that the total polymer composition may be extruded or formed at a temperature less than the temperature of decomposition of the blowing agent.

My method, in one embodiment, includes: extruding or otherwise forming a thermoplastic polymer composition into a fiber form, the forming or extrusion operation taking place at a temperature below the temperature of decomposition or expansion of the blowing agent employed, thereby producing a solid gasexpandable polymericfiber; and, thereafter, tufting or 2. otherwise securing the gas-expandable solid fibers, either alone or with other fibers of a natural or synthetic character, intoor to a base sheet, the tufting occurring at a temperature insufficient to expand the'blowing agent and the gas-expandable fiber; and heating the fiber s0 secured to decompose or expand the blowing agent and expand the diameter of the fiber tufted in the sheet backing material. Such expansion of diameter locks the fiber into the base sheet material, since on expansion the fiber so expanded contacts and is placed in a compressed state against the material of the backing sheet.

My invention is particularly adapted for use in preparing all polymeric synthetic-typetufted carpets, such as an indoor-outdoor carpet, or asurface required for an athletic field, tennis court, pool area or the like. For example, the tufted carpet produced by my invention may comprise a backing sheet-material composed of a nonwoven polypropylene fiber sheet having tufted therein into and through the sheet a gas-expandable fiber comprised of a synthetic polymer, such as nylon, polypropylene, polyether, polyethylene, polyester, acrylic, alone or admixed with other fibers, so that on expansion of the gas-expandable fibers, such fibers become locked into the polymeric backing sheet.

My invention, thus, comprises a tufted product, such as a carpet, which includes a backing sheet and a plurality of expanded cellular polymeric fibers secured to, such as tufted into and through, the backing sheet, the fibers providing a fibrousface surface, the fibers inthe backing sheet secured thereto by the contact and compression of at least a portion of the outer surface of the expanded cellular polymeric fibers'against the material on the backing sheet. The backing sheet may comprise a solid polymeric material, such as solid flexible thermoplastic sheet material, such as polypropylene or a vinyl-chloride resin, a cellular polymeric sheet material, or a natural or synthetic woven. or nonwoven material which has relatively small openinterstial areas therein. My tufted products include those products wherein expansion occurs'by fully expanding the entire gas-expandable fibers, such as in ahot-air oven, so that the fibers are fully expanded on both the back and face surfaces, as well as products wherein the fibers are heated, such as by radiant heaters, so that only the face or back or boththe face and back fibers have been heated to expand and form a cellular fiber. Less than full expansion of the expandable polymeric fibers is often desirable where solid fibers are desired for wear resistanceor other purposes. In addition, the unexpanded portionof the fibers will contain undecomposed blowing agents, which, on later subjecting to heat, such as a lighted cigarette or by exposure to open flame or high temperature, will cause the decomposition of the blowing agent, and, thus, aid-in preventing spreading of flame or aid in quenching the flame through the inert gases released'and the expansion of the polymer by the decomposed blowing agent, or by the blowing agent vapors, if such vapors are nonflammable, such as halocarbons.

For example, in one'embodiment of my invention, the back surface only of the gas-expandable tuftedfibers may be heated to cause expansion of the fibers on the back surface, the expansion extending slightly into the backing sheet, for example, lessthan 50 percent by depth of the backing sheet; such expansion causing the fibers to be secured to thebacking sheet, and yet, providing resiliant cellular back stitches, while the face of the tufted carpet contains the undecomposed blowing agent.

In another embodiment, heat may be directed solely toward the face surface of the tufted product to decompose the blowing agent in the gas-expandable fibers on the face surface, the fibers retained in place by the expansion downwardly into the backing material. In another embodiment, heat may be directed both to the face and back surfaces sufficient to expand the fibers on both surfaces. The heat may be sufficient to expand the face and back fibers only in part, so that the expanded diameter of such fibers locks in the nonexpanded smaller diameter fibers into the backing sheet or the fibers heated, so that the expanded fibers extend into both of the surfaces sufficiently so that the expanded fibers in the backing sheet prevent the fibers from being pulled out of the backing sheet material. In my method, the expansion of the fibers also softens the resin of the fibers and the backing material, so that subsequent cooling of the fibers and backing material after fiber expansion provides for additional adhesive strength due to the fusion of the fibers to each other and to the resin backing material.

In another embodiment of my invention, the face surface of the product may be heated in different areas to provide differing design effects through the difference between expanded and nonexpanded areas of the face surface. In addition, different types of gas-expandable fibers may be employed; i.e., having different polymers or blowing agents, which volatilize or decompose at different temperatures in the same or different resin compositions, so that heating the tufted product or solely the face surface provides for a mixture of expanded and nonexpanded fibers; i.e., cellular and noncellular, or fibers differing in cellular density or having areas raised in height greater than other areas of the carpet. Cellular fibers on a face surface provide a more resiliant face surface for walking or surface comfort and safety, while aiding in sound deadening. For example, a mixture of gas-expandable and nongas-expandable polypropylene fibers may be used, or vinyl-chloride resin fibers with blowing agents of differing decomposition temperatures used to provide a mixture of cellular densities. In another example, gas-expandable vinyl-chloride resin fibers may be heated solely on the face surface by radiant heaters, with different areas of the face surface fibers heated to different temperatures so as to provide for a design effect based on a different degree of expansion of the fibers; i.e., a different cellular density of the fibers, with some fibers in one area fully expanded to provide low-density fibers; e.g., less than 5 or pcf, and other areas partially expanded to high densities; e.g., to 10 to 30 pcf, and optionally, areas of no expansion.

The polymeric material used in forming the gasexpandable fibers in my invention may comprise a variety of natural and synthetic resinous materials, both thermoplastic and thermosetting, such as natural and synthetic elastomeric material, as well as thermoplastic material, the selection of the particular fiber based on the ultimate use of the product. Typical materials include any polymeric material which is capable of being expanded into a cellular product by the use of a blowing agent. Such materials would include, but not be limited to, those organic thermoplastic materials, such as polyesters, acrylics, polyamides, polyethers, and vinyl resins, like vinyl halide resins, such as vinyl-chloride resins to include polyvinyl chloride and vinyl-chloride copolymers with the esters of short-chain fatty acids, such as vinyl acetate, as well as with vinylidiene chloride, olefinic resins, such as C -C olefinic resins like polypropylene, polyethylene, copolymers of ethylene, propylene, butylene and the like as well as elastomeric polymers subjected to cross-linking or curing, such as butyl rubber, neoprene, polybutadiene, styrenebutadiene, styrene-acrylonitrile-butadiene and the like.

The polymeric materials may be formed into small diameter fibers through conventional forming tech niques, such as by extruding through a die or spinerette. The fibers may be employed alone or with other natural or synthetic materials in multiple strands. The diameter of the fibers may vary and where desired, the fibers may be of round, eliptical, flattened or other shape. For example, typical flat or ribbon-like fiber and use of such fibers which may be made gas-expandable are set forth in US. Pat. No. 3,] 10,905. The formation of the fibers containing a blowing agent and other additives as required should take place at a temperature insufficient to decompose or to decompose substantially the particular blowing agent being used, with the temperature so selected depending on the blowing agent and stabilizers employed in the polymeric mixture. Further, in another embodiment of my invention, the synthetic polymeric material containing a blowing agent may be extruded, coated, cast or otherwise employed over one or more materials employed in single or multiple strands as an inner core material of either natural or synthetic origin. The core material may, for example, be a fiber of cotton, rayon, wool, jute, cellulose, nylon, polyester, acrylic, vinyl resin, olefinic resin, and the like. The inner core fiber typically would be solid; that is, nongas-expandable, but if desired, may also, where it is synthetic, be gas-expandable to the same or different density than that employed for the outer coating. The gas-expandable material may be formed over a cellular core material or over a gasexpandable material so that on subsequent heating, the core and coating form a cellular product. The use of a single monofilament or a strand of monofilament as an inner core material may be used where it is desired to impart additional mechanical strength to the fibers employed, such as the use of an olefinic, polyester, nylon or acrylic resin, glass fibers or steel fibers or where, for example, to use an inexpensive material, such as cotton where it is desired to reduce the amount of the gasexpandable polymer employed as the outer coating. The thickness of the outer coating may vary from 2 to mils, depending on the depth and size of the ultimate fiber product desired.

The synthetic polymeric material to be employed in the fibers may typically include those plasticizers, stabilizers, curing agents, accelerators, pigments, dyes, oils, fillers and other additives desired and should also contain one or more blowing agents. Typically, the blowing agents would be used in the amount of from 0.1 to 25 parts of the blowing agent per 100 parts of the resin; for example, 1 to 15. A wide variety of blowing agents may be employed including those blowing agents which decompose in the application of heat to give an inert gas, such as nitrogen, hydrogen or carbon dioxide and the like, or may also include those liquid blowing agents, such as the fluorocarbons which on the application of heat vaporize to form a cellular product. The selection of a particular blowing agent is based on a melt viscosity of the polymeric material to be used and the temperature at which the material must be formed into the fiber and the decomposition characteristics and temperature of the blowing agent. Typical blowing agents which could be employed would include azodicarbonamide for the vinyl chloride resins, oxybisbenzenesulphonylhydrazide for other thermoplastic resins and dinitrosopentamethylenetetramine for the neoprene, butyl rubber, ABS resins and polybutadiene and the like. Other blowing agents may be selected from the Encyclopedia of Polymer Science and Technology, Volume 2, pages 532-565 by Henry R. Lasman, 1965.

The gas-expandable synthetic polymeric fibers may be employed in typical rug, carpet or pile fabric techniques in order to secure them to a sheet material used as a backing material. Of course, the fibers may be employed alone or with the other adhesive materials to aid in securing onto the backing sheet with my techniques employed to providegreater lock to the sheet material. The extrusion or forming of the fibers, as well as the placing the fibers into contact with or at least partially through, if not entirely through, the backing sheet, should be done at a temperature below the decomposition temperature of the blowing agent. After the tufting (which includes needle-punching or other similar processes), the product may then be exposed to a higher temperature and a decomposition agent in order to decompose the blowing agent, and thereby selectively expand the fibrous material to the formation of a foam fiber. On decomposition, the fibrous material will expand in diameter, pushing against the surrounding material of the backing sheet or the pile fibers, and thereby provide a greater lock of the fabric to the backing sheet. The foam density of the polymeric material should be selected to provide the cushioning effect desired together with what wear-resistant properties are needed. For example, high foam-density material may be desirable, for example, from to 50 pounds per cubic foot may be desirable where high wear resistance is necessary, such as in outdoor carpet, while lower foam density material where wear resistance is not important, such as from 2 to 15 pounds per cubic foot, may be desirable where cushioning effect and wear resistance is not the primary objective.

The backing material employed in preparing my products may comprise any sheet material either woven or nonwoven of natural or synthetic origin. Typically, however, the sheet material should be fairly solid or have a woven fabric having a low interstitial area so that upon expansion of one or more fibers, that the fibers will properly lock. Of course, with thermoplastic resins, an additional advantage of my invention is that the application of the higher temperatures to decompose the blowing agent will also provide for the thermoplastic resin to flow and adhere to the surrounding backing sheet or pile fibers, thereby also providing an adhesive effect to hold the fibers in place.

Typical sheet backing materials which may be employed would include paper or woven yarns composed of jute, sisal, resin-reinforced papers, as well as resinous sheet material, such as a gas-expandable thermoplastic resinous material like a gas-expandable vinylchloride or propylene sheet material, so that upon the application of the higher temperature, both the backing sheet and the yarns will expand to form a unitary product having a cellular backing sheet with cellular yarn secured directly thereto. Of course, the cellular foam formed either on the backing sheet or the fibers may be of the open or closed-cell as desired, although typically, the fibers formed will have a thin-skin outer coating to prevent the absorption of liquid spilled thereon. Other sheet materials would include paper sheet typically resin-reinforced; e.g., of screens, fiber glass, asbestos sheets, knitted, braided or other fabrics, such as stretch fabrics and the like. My gas-expandable fibers may be woven or formed into the backing material alone or with other natural or synthetic fibers. The gasexpandable fibers may be woven at spaced intervals through a jute backing. It is preferred that the same synthetic polymer be used in the backing and pile face.

1 special high-strength dies. The combination in such a polypropylene resin of an additive to reduce the melt viscosity of the resin, together with a blowing agent, permits the preparation of the solid gas-expandable fibers.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 includes a process in block diagram form, setting forth the applicants-process.

' FIGS. 1a and b are cross-sectional views of the carpet as prepared by the process of FIG. 1.

FIG. 1c is a fragmentary cross-sectional view of expanded fibers of FIG. 1b.

FIG. 2 is an illustrative cross-sectional view of a tufted carpet containing fully expanded tufted fibers.

- FIG. 3 is an illustrative cross-sectional view of a tufted carpet as in FIGS. 1a and b, except that the base sheet is cellular in nature.

FIG. 4' is an illustrative cross-sectional view of a tufted carpet, with solely the face surface of the carpet heated to expand the face surface fibers.

FIG. 5 is an illustrative cross-sectional view of a tufted carpet wherein both the face and back surface fibers are heated to expand the fibers.

EXAMPLE 1.

A gas-expandable polymeric composition is prepared by blending crystalline isotactic polypropylene resins having a melt viscosity of about 210C 82 parts; cis 4 polybutadiene rubber 15 parts; and azodicarbonamide blowing agent (Kempore 200, a fine particle-size blowing agent from National Polychemicals, Inc.) 3.0 parts. The composition having a reduced melt flow index is then extruded through a small spinerette die into a fine polymeric fiber employing a pressure suitable to force the resin composition through the spinerette and maintaining an extrusion temperature of not more than 180C; e.g., of about to C. The azodicarbonamide has a normal decomposition temperature of approximately C, which composition may be lowered based on the type of stabilizing additives employed in the polypropylene resin composition. For example, the decomposition temperature is lowered by the use of metal salt stabilizers like zinc, barium, potassium, cadmium, lead or combinations thereof. However, the resin composition is extruded into a fiber without substantial decomposition of the azodicarbonamide, and a gas-expandable solid fine 300 mil diameter resin fiber produced.

EXAMPLE 2.

A gas-expandable vinyl-chloride polymeric composition is prepared by blending into a vinyl-resin polymer plasticizer composition a vinyl-chloride resin in the amount of 100 parts; plasticizer such as dioctyl phthalate in the amount of 10 to 100 parts per 100 parts of resin; a zinc cadmium organic soap stabilizer in the amount of 4 parts per 100 parts of resin; a pigment, such as titanium dioxide, at 5 parts per 100 parts resin; and about 2 parts per hundred parts of resin of a blowing agent such as azodicarbonamide. This mixture is rolled into a substantially dry extrudable form on a roller mill and then extruded into fiber form through a spinerette die at a temperature of approximately below 170C, such as 160C, to provide a gas-expandable vinyl-chloride resin fiber. This vinyl-chloride resin, if desired, may also be extruded around a nylon core, the nylon employed for strength with the nylon inner core representing about half of the diameter of the fabric so formed.

EXAMPLE 3.

A gas-expandable polypropylene resin composition, such as prepared in Example 1, is incorporated, alone or with other fibers, into a backing sheet material by tufting said fibers at ambient temperatures -35C into and through the base material. The backing sheet may comprise a nonwoven sheet composed of nonexpandable nonwoven polypropylene or gas-expandable polypropylene fibers, such as prepared in Example 1. Thereafter, the tufted fibers in the backing sheet are heated, such as in a hot-air oven, to permit the decomposition of the blowing agent and the expansion in diameter of the fibers of from about 2 to 6 times their diameter, thereby permitting the fibers by such expansion to be locked into the base sheet material. The polypropylene fibers are expanded by heating at a temperature of approximately 175 to 215C. If desired, infrared heaters or radiant gas burners may be employed to direct heat only to the backing or face surface of the tufted material, so that the polypropylene fibers are only heated and expanded on that surface.

EXAMPLE 4.

Gas-expandable vinyl-chloride resin fibers, for example, prepared in Example 2, are tufted into and through a closely woven fabric sheet material, such as a jute sheet, in a typical manner, for example, as set forth in US. Pat. No. 3,110,905. The tufting occurs at a temperature; e.g., room temperature, less than 40C, less than the temperature sufficient to decompose the azodicarbonamide blowing agent employed in the fibers. The tufted product containing the polymeric fibers is then subject to a temperature, for example, a hot-air oven or infrared heaters, directed to one or both surfaces, greater than about 175C, for example 190 to 200C, in order to expand fully and fuse the vinyl resin and provide for the decomposition of the azodicarbonamide to form cellular fibers. The backing sheet material employed may be a solid thin flexible platicized thermoplastic sheet composed of a vinyl-chloride or other resin or of nonwoven polymeric or natural fibers, or a gas-expandable vinyl-chloride or other resin sheet material, such as a calendered sheet, where upon heating, the backing material also decomposes and becomes a cellular product. If desired, another backing sheet, such as of vinyl-chloride resin sheet material, may be secured as another backing sheet to the tufted product prior to heating.

Reference is now made to FIG. 1 wherein the gasexpandable polymeric fibers are prepared, such as by extruding a thermoplastic-extrudable polymeric composition, or by casting, molding, dipping or other techniques. The fibers are tufted into and optionally through a backing sheet at a temperature below the expansion temperature of the fibers (such as by needlepunching chopped fibers), and, thereafter, the fibers tufted to the backing sheet are heated at least on one surface to a temperature to expand the fiber diameter, thereby locking the fibers into the backing sheet through expansion of the outer surface of the fibers against the material in the backing sheet.

As shown more particularly in FIGS. la and b, the tufted product, such as a carpet 10, is prepared comprising a base sheet 12 having a face surface 16 and a back surface 18; for example, a thin nonwoven flexible thermoplastic polypropylene backing sheet, and solid gas-expandable fibers 14 comprising a polypropylene resin are tufted through the base sheet 12, the tufted product characterized by a fibrous face surface 22, and a plurality of raised fibrous back stitches 20. In the product illustrated, the tufted fibers are shown as having continually formed back stitches. If desired, the product may be prepared by needle-punching separate short fiber lengths into the base sheet, rather than having continuous uniformly stitched fibers with raised back stitches. For example, fibers may be garnetted onto the surface of the base to form a batt of 3 to 12 inches in height, and then the fiber batt needlepunched into a backing sheet. Heat 26 is then directed toward the back surface of the tufted product, for example, by the use of radiant gas burners, infrared heaters or other means, so as to heat only the back stitches and back surface, and a portion of the fibers extending into the backing material to a temperature sufficient to decompose the blowing agent and expand the diameter of the fibers. The cellular fibers 24, after the heating of the back stitches to this temperature, such as a temperature of over 210C, are formed while maintaining a temperature lower than the decomposition temperature at the face surface of the product. The face surface may be a nonheated surface, or heated only slightly or cooled; that is, placed in contact with the cooling roll to maintain a desired temperature gradient between the face and back surfaces. My method provides for only the fiber back stitches to expand, a portion of them extending into the backing material, thereby locking the tufted fibers into the backing material, and thereby providing a cellular backing to the tufted product, while the face surface remains essentially as a plurality of solid gas-expandable polymeric fibers.

The product preferred is a particularly desirable flame-retardant product in that later exposure of the face surface fibers during use permits the undecomposed blowing agent to decompose and to aid the quenching and preventing the spread of flames. Thus, not only will my technique provide for an improved tuft lock due to expansion and fusion, but provide some flame-retardantcharacteristics on the face surface of the fibers, which flame-retardant characteristics do not alter the character of the fiber employed which remains in place during the carpet life. Flame retardancy, by employing a chemical blowing agent on the undecomposed face surface fibers, is particularly useful where the localized conditions of heat or flame are applicable, such as where a lighted cigarette or cigar is dropped onto the carpet. As illustrated, the gas-expandable tufted back stitches 24 have an expansion approximately 2 to 4 times the diameter of the nonexpandable solid fibers 14, with the cellular expansion generally tapering off as the fibers in the backing sheet 12 approach the face surface 16 of the backing sheet material 12. Therefore, the expandable fibers are fully expanded at the back surface 18, but as the radiant heat from the heaters 26 fail to penetrate fully the backing sheet material, the amount and degree of expansion tapers off. Often to provide good tuft lock, the fibers should be expanded for a depth of about 50 to 80 percent into the base sheet material 12.

FIG. 2 illustrates a tufted cellular carpet tile product 28 composed of a plurality of fully expanded polymeric tufted fibers 32 which have been tufted through a backing sheet material, such as a fibrous material 30, for example, a jute material or a fiberglass screen material, with a solid flexible plasticized vinyl-chloride backing sheet 34 secured to and covering the back stitches of the expanded fibers 32, which is a plasticized vinylchloride fused resin layer. In this example, the product is prepared as in FIG. 1, except that prior to heating of the gas-expandable fibers, a thin layer of a vinylchloride plastisol composition is coated over the back surface of the gas-expandable fibers, and, thereafter, the coating fused by heat and the fibers expanded throughout the entire length by heating in a hot-air oven, for example, 190 to 200C.FIG. 2, therefore, illustrates a tufted product and process whereby full expansion of the fibers throughout the backing sheet, with a further optional embodiment of preparing a solid resin backing to prepare a tufted carpet tile product having a solid resin backing and a face surface of cellular fibers.

FIG. 3 illustrates a tufted carpet 39 wherein a gasexpandable base sheet, for example, a thin calendered vinyl-chloride resin sheet containing undecomposed azodicarbonamide, is employed, which, on heating the fibers on the back surface as in the process as shown in FIG. 1, also expands the backing sheet material into a cellular sheet material 36, while the face fibers 38 remain noncellular as solid gas-expandable fibers. The back stitches of the fibers 40 are fully expanded cellularfibers, and are locked into the expanded base 36. In this technique, heat has been applied solely to the back surface and/or a blowing agent employed in the backing material 36 to provide for full decomposition of the backing material prior to the full decomposition of the blowing agent on the back stitches 40. In this manner, the expansion of the backing material 36, together with the expansion of the back stitches 40 extending into the backing material, provides excellent tuft lock, while the face surface of the tufted carpet remains in its essentially solid gas-expandable fiber-looped form, and a product with a flexible integral cellular base is provided.

FIG. 4 illustrates a tufted product 41 having a fibrous backing sheet 42 through which polymeric fibers 44 have been tufted. The polymeric fibers are heated solely on the face surface by radiant heaters to provide for full expansion of the fibers on the face surface. The expanded fibers 44 extend from the face surface downwardly into the base sheet material 42 in an amount sufficient to secure the expanded face fibers to the'base sheet 42. In addition, an adhesive material 46, such as a latex, has been coated onto and over the nonexpanded gas-expandable polymeric fibers forming the back stitches 48, further locking the fibers to the backing sheet 42. This process and product, therefore, provides for a tufted carpet having a cellular face, while the undecomposed blowing agent in the back stitches and the face fibers also serve as a flame-retardant mechanism in the event of heats being placed on the back surface.

FIG. 5 illustrates a tufted carpet 52 having both face and back fibers of a cellular nature. Gas-expandable polymeric fibers are tufted through a solid flexible thermoplastic backing sheet 54, and, thereafter, both the face and back surfaces of the tufted fibers are heated through

heaters

62 and 64 to a temperature to decompose the blowing agent in the gas-expandable polymeric fibers to provide for cellular polymeric fibers 56 on the face and fibers as back stitches, the fibers extending from the face and back surfaces into the backing sheet 54. The backing sheet 54 contains a portion of smaller-diameter nonexpanded solid fibers 66 which have not been heated sufficiently'to effect expansion. The fibers are securely locked into the back and face surfaces through the expansion of the polymeric fibers.

The product produced and illustrated by my invention is unique in that the use of hardened adhesives in the back surface may be totally avoided, while theface fabrics or the fabrics on the face or back, or both, being expandable on having a foam density of desired character may provide a softness, cushioning and resiliency effect where the product is employed as a carpet, garment underlining or interlining or the like. Such materials cannot be prepared by the direct tufting of an already expanded cellular material into the backing material often due to the fragile nature of the cellular material, since the cellular material, often particularly of a low-foam density, would not withstand the needlepunching or tufting operation without deterioration of the fibers.

The heating of the surfaces has been illustrated by radiant heaters; however, such heating may also be carried out by blowing hot air onto the surfaces or placing the surfaces to be heated or protected into contact with one or more heating or'cooling rolls.

Also for the purposes of illustration only, my tufted products have been shown having a continuous strand of uniform back stitches; however, it is recognized that a variety of techniques may be employed in order to force fibers into or through, or both, a random or irregular or regular pattern onto a backing sheet material. Further, the gas-expandable fibers have been illustrated by being prepared by an extruding technique; however, it is recognized that other methods of forming the fibers, such as coating, dipping, molding or other operations, may be employed. Other techniques and modifications of my invention will be apparent to those people skilled in the'art, and, accordingly, attend to be bound by the scope of the claims hereto.

What I claim is:

l. A product which comprises a backing sheet and a plurality of expanded cellular polymeric fibers secured to the backing sheet, the fibers providing a fibrous face surface, the fibers in the backing sheet secured thereto by the contact and the compression of at least a part of the outer surface of the cellular polymeric fibers against the material in the backing sheet.

2. The product of claim 1 wherein the backing sheet is a solid flexible thermoplastic sheet material.

3. The product of claim 2 wherein the backing sheet is a plasticized vinyl-chloride resin.

4. The product of claim 1 wherein the backing sheet is a cellular polymeric sheet material.

5. The product of claim 1 wherein the backing sheet is a nonwoven polymeric fibrous sheet material.

6. The product of claim 5 wherein the backing sheet is composed of a nonwoven polypropylene fibrous sheet material.

7. The product of claim 1 wherein the polymeric fibers comprise a solid intercore material surrounded by an outer cellular core material.

8. The product of claim 1 wherein the fibers are tufted loop-like back stitches on the back surface of the backing sheet.

9. The product of claim 1 wherein the fibers are tufted into and through the backing sheet, and only the fibers on the face surface are cellular fibers, and the fibers on the back surface are noncellular fibers and contain an unexpanded blowing agent.

10. The product of claim 1 wherein the fibers are tufted into and through the backing sheet, and only the fibers on the back surface are cellular fibers, and the fibers on the face surface are noncellular fibers and contain an unexpanded blowing agent.

11. The product of claim 1 wherein the fibers are tufted fibers, and a-portion of the fibers are noncellular and contain a nonexpanded blowing agent, while the face and back fibers, or both, are cellular fibers.

12. The product of claim 1 wherein the cellular fibers in contact with the backing sheet extend from one or both surfaces of the backing sheet to a depth of 50 percent or more into the backing sheet.

13. The product of claim 1 wherein the face surface contains different areas of cellular fibers and noncellular fibers, the cellular fiber area and the noncellular fiber area differing in fiber height, creating a predetermined design effect on the carpet surface.

14. The product of claim 1 wherein the fibers are secured into and through the backing sheet, the product having a solid polymeric coating layer integrally bonded to the back surface of the backing sheet.

15. The product of claim 1 wherein the fibers are secured into and through the backing sheet, and the fibers are in a fully expanded condition on the face and back surfaces and through the material in the backing sheet.

16. In a method of preparing a fibrous product, which method comprises providing a plurality of gasexpandable polymeric fibers containing an expanding agent therein, securing such fibers to a backing sheet to form a fibrous face surface, and heating the fibers so secured to effect an expansion of the diameter of the fibers by the expanding agent, the improvement which comprises:

heating the fibrous face surface or the back surface,

or both surfaces, to a temperature sufficient to effect expansion of the expanding agent and the formation of cellular polymeric fibers on the heated surface, so as to expand the fibers on such surface, the expansion of the fibers extending at least partially into the backing sheet, the expansion of the fibers within the backing sheet securing the fibers therein by the contact of the expanded cellular fibers and the compression of the outer surface of such cellular fibers against the material of the backing sheet, while at least some of the gasexpandable fibers between the face and back surface retain their gas-expandable condition and contain an expanding agent.

17. The method of claim 16 which includes heating only the fibers on the face surface of the backing sheet to form cellular polymeric fibers on such face surface.

18. The method of claim 16 wherein the fibers extend into and through the sheet material, and includes heating only the fibers on the back surface of the backing sheet to form cellular polymeric fibers on the back surface, the expanded fibers extending into the backing sheet and toward the face surface.

19. The method of claim 16 which includes heating by directing radiant heat only towards the surface of the backing sheet to be heated.

20. The method of claim 16 which includes bonding a polymeric cellular backing layer to the back surface of the product.

21. The method of claim 16 wherein the backing sheet comprises a gas-expandable thermoplastic sheet material, which, on heating, expands to form a cellular backing sheet.

22. The method of claim 16 wherein the backing sheet comprises a nonwoven polypropylene fibrous sheet material.

23. The method of claim 16 wherein the fibers extend into and through the backing sheet and which includes heating both the face and back surfaces of the gasexpandable fibers to expand the fibers on the face and back surfaces, but insufficient to expand or fully expand the fibers within the backing sheet, the expansion of the fibers on the face and back surfaces locking the fibers into the backing material.

Claims

1. A PRODUCT WHICH COMPRISES A BACKING SHEET AND A PLURALITY OF EXPANDED CELLULAR POLYMERIC FIBERS SECURED TO THE BACKING SHEET, THE FIBERS PROVIDING A FIBROUS FACE SURFACE, THE FIBERS IN THE BACKING SHEET SECURED THERETO BY THE CONTACT AND THE COMPRESSION OF AT LEAST A PART OF THE OUTER SURFACE OF THE CELLULAR POLYMERIC FIBERS AGAINST THE MATERIAL IN THE BACKING SHEET.

11. The product of claim 1 wherein the fibers are tufted fibers, and a portion of the fibers are noncellular and contain a nonexpanded blowing agent, while the face and back fibers, or both, are cellular fibers.

16. In a method of preparing a fibrous product, which method comprises providing a plurality of gas-expandable polymeric fibers containing an expanding agent therein, securing such fibers to a backing sheet to form a fibrous face surface, and heating the fibers so secured to effect an expansion of the diameter of the fibers by the expanding agent, the improvement which comprises: heating the fibrous face surface or the back surface, or both surfaces, to a temperature sufficient to effect expansion of the expanding agent and the formation of cellular polymeric fibers on the heated surface, so as to expand the fibers on such surface, the expansion of the fibers extending at least partially into the backing sheet, the expansion of the fibers within the backing sheet securing the fibers therein by the contact of the expanded cellular fibers And the compression of the outer surface of such cellular fibers against the material of the backing sheet, while at least some of the gas-expandable fibers between the face and back surface retain their gas-expandable condition and contain an expanding agent.

23. The method of claim 16 wherein the fibers extend into and through the backing sheet and which includes heating both the face and back surfaces of the gas-expandable fibers to expand the fibers on the face and back surfaces, but insufficient to expand or fully expand the fibers within the backing sheet, the expansion of the fibers on the face and back surfaces locking the fibers into the backing material.