Styled pile fabrics and method of making the same

Dec. 20_s 1SSS _{D> R HULL} 3,293,104

ST7L3D FILE FABRICS AND METHOD OF MAKING THE SAMR Filed Nov. 23, 1962

FIG. S

CONTORTED

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FIG. 2

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THICKMESS OF BLOCK

Ff G* 4BACMG ATTACHED

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LAYER

INVENTOR

DONALD ROBERT HULL

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BY

ATTORNEY

3,293,104

Patented Dec. 20, 1966

United States Patent Office

3,293,104

STYLED PILE FABRICS AND METHOD OF MAKING THE SAME

Donald Robert Hull, Wilmington, Del., assignor to E. I. du Pont de Nemours and Company, Wilmington, Del., a corporation of Delaware

Filed Nov. 23,1962, Ser. No. 239,716

Claims. (CI. 161—67)

This invention relates to the styling of textile articles and more particularly to improved methods of styling and unique products resulting therefrom.

Many methods are currently known for styling of pile fabrics such as carpets by conventional techniques of embossing, cutting, printing, sculpturing, and the like. However, most of the current mechanical methods for creating, patterning or texturing designs in such textiles as carpets are carried out by hand, which makes them an expensive element in the final cost of the carpet.

One of the objects of this invention is to provide an improved process for styling textile articles. Another object is to provide such a styling process which can be performed .as a high-speed, easily controlled and mechanized continuous process. A further object is to provide a process particularly adapted to styling fiber-on-end textiles. Another object is to provide a group of novel pile fabrics, the surface of which exhibit a wide variety of patterned and textured effects. Other objects will be aparent from a further description of the invention given below.

The process of the invention relates to the manfacture of a styled pile fabric by the series of steps including the adherence of a backing to a layer of porous, self supporting material comprising a plurality of contorted filamentary structures. These structures are so arranged to be overlapping, aligned in generally the same direction, and interconnected throughout the three dimension of the layer. The layer is further characterized as having a fiber density below 25 lbs./ft.³ and having at least one substantially planar surfaces defined by filament ends which will be adhered to the backing. According to this process, before adhering the layer to the backing, the layer is provided with a predetermined pattern of non-intersecting, substantialy parallel slits extending throughout a single dimension of the layer to intersect the mentioned planar surface, i.e. that to ultimately be adjacent the backing, at an angle no less than about 50°. The resulting patterned material is then stretched in a direction substantially perpendicular to the plane of the slits to provide openings of lower fiber density than the remainder of the structure. In such a stretched condition, the layer is then adhered to the backing to form a unique styled pile fabric. If desired the points of interconnection within the material, where such points are formed by a soluble binder, can be thereafter removed to leave simply points of contact. In any event the resulting product will comprise the backing and filamentary structures but will be unque because of the non-uniform distortion of the layer. Visually, areas of the layer having slits before the stretching action become a pattern of isolated voluminal sections or openings having an average fiber density less than 50% of the average fiber density of the remaining layer. Moreover the geometrical configuration of the sections will extend throughout a single dimension of the layer to intersect the planar surface adjacent the backing in the manner as did the original slits. Normally these isolated sections will appear substantially in the form of cylinders wherein each of the bases thereof are in the planes of opposite faces of the layer.

The invention is further illustrated in the accompanying drawings in which FIGURE 1 represents a photo20 graph of the pile surface or top view of a typical carpet made in accordance with this invention. FIGURE 2; represents a schematic diagram of a bonded filamentary block in which a series of slits have been cut in the same general direction as the lengths of the filaments. It will be apparent that a corresponding filamentary sheet sliced from such a block and provided with slits would only differ in thickness. FIGURE 3 represents a schematic diagram· of the bonded block of FIGURE 2 after one face of the block has been attached to a backing. FIGURE 4 represents an expanded sheet material attached to a backing; such product embracing the case where an expanded sheet has been attached to the backing and also where the material of FIGURE 4 has been sliced transverse to the direction of the filaments.

A suitable method for carrying out the present invention follows. A bonded block of filaments is first prepared by arranging a group of continuous filaments each having a three-dimensional crimp, so that the filaments are aligned generally in the same direction and are overlapping when they are placed in a mold. A suitable binder is applied to the assembly of filaments while held together in the mold, and the excess binder is then allowed to drain from the mold so that adjacent filaments are bonded together discontinuously by point bonds along their lengths. After setting of the binder and removal of the body from the mold there results a porous selfsupporting block which is composed of an interconnected network of highly crimped filaments bonded together at isolated points along their lengths. The thickness direction of the block is defined as the direction in which the filaments are aligned. Next the block is sliced transversely to the direction of the filaments to provide a face of cut filament ends. Thereafter a series of small isolated slits are made in the block by inserting a sharp knife at several places in one face of the block and cutting slits, preferably uniplanar, that run the full thickness of the block in generally the same direction as that of the filaments. These slits are made such that the planes thereof are approximately parallel to one another in direction and, in a preferred embodiment, will be substantially at right angles to the two opposite faces of the block. Merely cutting the slits does not, of course affect the fiber density throughout the material. The dimensions of each slit are such that it extends the full thickness of the block in the thickness direction of the slit, but the other two dimensions of the slit are much less than the width and length dimensions of the block. For example, in a block of bonded filaments measuring 24 inches x 24 inches x 24 inches, each slit may be 24 inches in thickness, 2 inches long and Vs inch wide. Next a stretching force is applied to the block in a direction perpendicular to the direction of the filaments and at the same time perpendicular to the plane of the slits. This stretching force enlarges the size of each rectangular slit to· an essentialy elliptic cylindrical opening having a major axis 1¾ inches long and a minor axis % inch wide. The stretching force causes the filaments to separate at the openings and provide a larger opening free from filaments than before stretching. A backing layer such as burlap is then coated on one face with a suitable permanent adhesive and the coated face is pressed flat against the bottom face of the block containing the cut filament ends in the face. A cutting blade is then used to make a transverse slice through the block at a distance of Vz inch or so, depending upon the desired pile thickness, from the plane of attachment of one face of the block to the backing to provide a backed article having a pile layer. Preferably, the binder composition is then removed from the pile layer by washing with a solvent in which the binder is soluble. This results in a pile fabric having a textured or patterned appearance on the

3,293,104 pile surface. The areas of the stretched openings in the pile layer become areas where virtually no filaments are attached to the backing. After removal of the binder, the free ends of the filaments in the pile layer adjacent to the openings tend to expand into the voids created by the openings which results in areas on the surface of the pile which exhibit lower pile height and reduced fiber density in comparison with the volume of the pile. Desirably the stretching is effected to such as extent that the elongated dimension is increased in length by at leart 5%. The fiber density of sections defined by the opening may be from 0 to 50% of the remaining fiber density.

The pile fiber density or simply “fiber density” reported in pounds per cubic foot is a measure of the density of the fibers in the pile layer of the backed carpet or other specimen from which layer the binder has been removed, or in other words the density of the shearable fiber above the adhesive line. This pile fiber density is calculated by dividing the effective pile weight of the fibers in the pile layer by the volume of these fibers occupy when the specimen is under a load of 0.1 p.s.i. This volume is determined by multiplying the average width by the average length of the conditioned carpet specimen by the effective pile height, and then applying suitable conversion factors to obtain the volume in units of cubic feet.

A full description of the filamentary materials employed in accordance with this invention for the production of styled pile fabrics is set forth in C. R. Koller U.S. application Serial No. 787,662, filed January 19, 1959, now U.S. Patent No. 3,085,922. These materials are of a porous character and have a plurality of contorted, e.g. crimped, filamentary structures which overlap, are aligned generally in the same direction, are interconnected throughout the three dimensions of the material and the material has a fiber density below 25 lbs./ft.³. Although a description of these materials, including definitions of the terms used on connection therewith, is fully set forth in the above Koller application, the disclosure of which is specifically incorporated herein by reference, they will be briefly mentioned herein. By “contorted” it is meant that the profile (i.e. side elevation) of an individual filament is irregular (i.e. not straight) when the filament is viewed from at least one side. In addition to being contorted, it is necessary that such filamentary structures overlap adjacent structures throughout the three dimensions of the article. By the term “overlap” is meant that in at least one view, a filamentary structure crosses over, with or without touching or attachments, an adjacent filamentary structure. Furthermore it is critical to such structures that the contortion and overlapping of the filamentary structures do coact or are allowed to coact with one another. By “coact” is meant that the contortion and relative placement of the filamentary structures are such that they assist one another in producing and maintaining the claimed structures both with respect to the general alignment of the filamentary structures and their spacing with respect to each other to achieve the desirable densities contemplated.

The initial filamentary material may be in any of a variety of forms, for example, carded webs of substantially aligned staple fibers or bodies of substantially aligned filamentary structures prepared from a warp of sliver, top, roping, roving, tow, stuffer box crimped tow, steam bulked tow, steam crimped continuous filament yarn, gear crimped continuous filament yarn, twist setback twisted continuous filament yarn, knife edge crimped continuous filament yarn, two-component bulky continuous filament yarn, spun yams, and many others. Any of the above procedures may then be followed to prepare the layer of material for use in this invention.

In preparaing a block or sheet material of contorted fibers a wide variety of polymeric compositions may be employed. Typical of the fibers and filaments which may be employed are those made of polyamides, such as poly (hexamethylene adipamide), poly (meta-phenylene isophthalamide), poly(hexamethylene sebacamide, polycaproamide, copolyamide and irradiation grafted polyamides, polyesters and copolyesters such as condensation 5 products of ethylene glycol with terephthalic acid, ethylene glycol with a 90/10 mixture of terephthalic/isophthalic acids, ethylene glycol with a 98/2 mixture of terephthalic/5 - (sodium sulfo) - isophthalic acids, and trans-p-hexahydroxylylene glycol with terephthalic acid, ₁₀ self-elongating ethyleneterephthalate polymers, polyacrylonitrile, copolymers of acrylonitrile with other monomers such as vinyl acetate, vinyl chloride, methyl acrylate, vinyl pyridine, sodium styrene sulfonate, terpolymers of acrylonitrile/methylacrylate/sodium styrene sulfonate 15 made in accordance with U.S. Patent 2,837,501, vinyl and vinylidene polymers and copolymers, polycarbonates, polyacetals, polyethers, polyurethanes such as segmented polymers described in U.S. Patents 2,957,852 and 2,929,804, polyesteramides, polysulfonamides, polyethylenes, 20 polypropylenes, fluorinated and/or chlorinated ethylene polymers and copolymers (e.g., polytetrafluoroethylene, polytrifluorochloroethylenes), cellulose derivatives, such . as cellulose acetate, cellulose triacetate, composite filaments such as, for example, a sheath of polyamide around 25 a core of polyester as described in U.S. Patent 3,038,236, and self-crimped composite filaments, such as two acrylonitrile polymers differing in ionizable group content cospun side by side as described in U.S. Patent 3,038,237, regenerated cellulose, cotton, wool, glass, metal, ceramic 30 and the like. Blends of two or more synthetic or natural fibers may be used, as well as blends of synthetic and natural. Other fibers such as silk, animal fibers such as mohair, angora, vicuna, are also suitable.

The self-supporting sheet material may be prepared 35 from a wide variety of forms of fibers and filaments, having any of the above-mentioned compositions, such as, for example, continuous monofilaments, continuous multifilaments, carded webs, warp, sliver, top, roping, roving, tow, bulked tow, bulked continuous filament yarn, spun 40 yarn, batts, felts, papers and other non-woven Webs, and the like. The fibers and filaments used as raw material may be either crimped or uncrimped, bulked, or unbuiked, drawn or undrawn or twisted or untwisted. The denier of the filaments is not critical and may vary from about 0.5 to about 50 denier or even higher.

The use of a binder is preferred to interconnect the filamentary structures at a plurality of points along their length. Depending upon the use desired these may be either soluble or insoluble, and may be either thermo5θ plastic in nature of may be thermosetting for subsequent •reaction with a curing agent to form a cured polymer. By “binder” is meant the additional material used to attach the filaments to each other. Normally these materials will be used in an amount of at least about 0.5% by weight based on the filamentary structures. If it is desired -to remove the binder a soluble binder will be em ployed which may be either organic-soluble or watersoluble. Suitable organic-soluble binders include natural rubber or synthetic elastomers (e.g., chloroprene, butadienestyrene copolymers, butadiene-acrylonitrile copolymers), which may be used in the form of a latex dispersion or emulsion or in the form of a solution, vinyl acetate polymers and copolymers, acrylic polymers and copolymers such as ethyl acrylate, methyl acrylate, butyl acrylate, methyl methacrylate, acrylic acid/acrylic and methacrylic ester copolymers, cellulose nitrate, cellulose acetate, cellulose triacetate, polyester resins such as ethylene terephthalate/ethylene isophthalate coplymers, polyurethanes such as the polymer from piperazine and ethylene γθ bis-chloroformate, polyamide polymers, and copolymers, 'methoxymethyl polyamides, vinyl chloride polymers and copolymers such as vinyl chloride/vinylidene chloride copolymer lattices. Alcohol soluble polyamide resins are also suitable organic-soluble binders. Suitable water75 soluble binders include materials such as polyvinyl alco3,293,104 hoi, sodium alginate, acrylic acid polymers and copolymers such as polyacrylic acid, carboxymethyl cellulose, hydroxyethyl cellulose, dextrins, animal glue, soybean glue and sodium silicate. Suitable binders which are insoluble in organic solvents include polytetrafluoroethylene 5 and ureaformaldehyde resin lattices.

Additional suitable binder compositions include chlorosulfonated polyethylene; butyl rubbers, such as isobutylene/isoprene copolymers; polyhydrocarbons, such as polyethylene, polypropylene and the like and copolymers jq thereof; high molecular weight polyethylene glycols sold under the trade name of Polyox; epoxide resins, such as the diepoxide of bisphenols and glycols; polystyrene, alkyd resins, such as polyesters of glycerol with phthalic or maleic acid; polyester resins such as from- propylene 15 glycol-maleic anhydride-styrene; phenol-formaldehyde resins; resorcinol-formaldehyde resins; polyvinyl acetals, such as polyvinyl butyral and polyvinyl formal; polyvinyl ethers, such as polyvinyl isobutyl ether; starch, zein, casein, gelatine, methyl cellulose, ethyl cellulose, poly- 20 vinyl fluoride, natural gums, polyisobutylene, shellac, terpene resins and rosin soaps. Segmented polymers, such as spandex polymers, polyether amides, poyether urethanes (e.g. those in U.S. 2,929,800) and polyester urethanes are also suitable. 25

The adhesives which may be used when applying the backing are varied. By “adhesive” or “glue” is meant the material used to cause the filamentary structures and sheet materials to adhere to the backing or is meant the material used to constitute the backing. Illustrative ad- 30 hesives are: chloroprene rubber, elastomeric foams and sponges, butadiene-styrene rubber, polyvinyl chloride resin (e.g. those in combination with either a polymeric plasticizer or a monomeric plasticizer curable after application of the adhesive), polyurethane resins, polyamide 35 copolymer of hexamethylene diamine and adipic and sebacic acids, casein resin, and epoxy resins such as the diepoxide of 2,2-bis(parahydroxyphenyl)propane. Illustrative backings are: woven fabrics such as burlap, canvas, and nylon scrim fabrics, knit fabrics such as nylon 40 tricot, nonwoven fabrics such as polyethylene or polypropylene fiber webs, resin bonded polyethylene terephthalate fiber .webs, papers of cellulosic and/or synthetic fibers, paper felts such as asphalt impregnated cellulose, elastomeric foams and sponges, plastic films such as from 45 polyethylene terephthalate, polypropylene and polyvinyl chloride polymers, metal, foils and rigid sheets such as fiber glass reinforced polyester resins, metals, ceramics and wood, elastic, stretchable or shrinkable fabrics and films, and the like. 50

The slits made in the porous self-supporting body of bonded filaments may be accomplished by any suitable means such as a sharp knife or other cutting blade for making a planar cut in the thickness or filament direction of the body without removing an appreciable quantity of 55 filaments from the body. The slits must be isolated in the sense each cannot be connected to the outside face or edge of the body and so that each slit does not intersect another slit in the volume of the body. A plurality of the isolated slits should penetrate the volume thickness of the gq body in the direction of the filaments from one face to the other. The planes defined by the slits should intersect at an angle no less than about 50° the face which will be attached to the backing. Angles less than 50° would be unsatisfactory for the reason that excessive quantities 35 of filamentary structures would be removed. In addition to the essential isolated slits in the body, there may also be a few small slits made from any of the faces of the body provided that they do not run the full dimension of the body from where they start, but only penetrate 70 into the volume a short distance. The thickness direction of each slit should be at least half the thickness of the body although a plurality of the slits must run the full thickness dimension of the body. The other two dimensions of each slit must be shorter than the width and 75 length of the block, that is, such that the slit does not extend throughout their length. Each slit may be of essentially identical cross-sectional shape or may be of somewhat different dimensions or at slightly different angles. A slit will normally be cut in the thickness direction of the body substantially parallel to the average direction of the filaments running through this thickness dimension, but for some uses it may be made in the thickness direction of the body at a small transverse angle to the average direction of the filaments, for example, up to 40° either side of the average direction of the filaments.

For purposes of practicing the invention, the porous self-supporting body of bonded filaments may be any convenient size depending upon the nature of the final textile article desired. Reference is made herein to the terms “body,” “block” and “sheet.” The term ‘block” is usually applied to a body having a relatively large thickness in the direction of the filament length, whereas the term “sheet” is usually applied to a body having a relatively small thickness in the direction of the filament length. Thin sheets may be sliced from thicker blocks of bonded filaments either before or after the slits are made in the body of bonded filaments. After the body containing enlarged openings has been attached to a backing, the resulting backed textile articles may be employed as such for certain end uses, or it may be desirable to remove a portion or all of the binder from the pile layer. If the binder is removed from the pile layer in the backed article, other materials may be applied to the backed textile article to additionally modify the properties thereof.

The primary advantage of this invention is that it provides a versatile styling technique for making backed textile articles which is uniquely applicable for making pile fabrics by a high-speed, easily controlled, mechanized continuous process. This method of styling provides an economic advantage in styling carpets, since in the present process none of the costly pile fiber need be lost in the process. This feature, it will be apparent, would not be realized by cutting large openings in a block or sheet material followed by simply removing the severed sections and then adhering to a backing. Another advantage is that the present process provides greater flexibility in styling carpets than former methods available for styling tufted and woven carpets. Hence a wider variety of textured and patterned pile surfaces are made available. In addition, the process provides a method of producing pile fabrics having lower fiber density in the pile, while at the same time retaining the important aesthetics and mechanical properties in the pile fabrics. The invention also provides a method for changing the compressional characteristics of textile articles such as cushions by means of introducing volumes of lower fiber density in the cushion products.

The present invention is useful for preparing a wide variety of textile articles in the form of floor coverings such as carpets and tiles, upholstery fabrics, furs and fleeces, garment interliners, blankets, cushions, mattresses, fibrous laminated structures, sponges, insulating materials, filters for gases, liquids, and solids, and the like.

The following example illustrates a specific embodiment of this invention but is not intended to limit the scope of the invention.

Example

The filaments used are a warp of 120 ends of continuous filament polyhexamethylene adipamide yarns (1020 denier, 68 filaments, Vz “Τ' twist, having a trilobal cross section). The warp is bulked with steam under the conditions disclosed in Example 2 in Table III of Belgian Patent 573,230 and subsequently aligned in the same direction and assembled in a mold 30 x 30 x 12 thick with the fiber ends all directed toward the top and bottom (30 x 30 faces) of the mold. Thereafter the assembly is impregnated with an excess of a 6% solution in an ethanol/water (80/20 by volume) solvent of a soluble

3,293,104 terpolymeric binder formed by condensing together caprolactam, hexamethylene diamine, adipic acid and sebaic acid so as to provide substantially equal proportions therein of polycaproamide, polyhexamethylene adijamide and polyhexamethylene sebacamide. The excess of the binder solution is drained from the fiber assembly and the assembly is heated to remove the solvent and solidify the binder. The bonded fiber block is removed from the mold and found to have a fiber density of 4.1 Ibs./cu. ft. and a binder content of 4% based on the weight of the fiber. The bonded block is sliced transversely to the filaments in a plane parallel with the top of the block (30 x 30 face) to give % thick porous self-supporting sheets of bonded fibers with the direction of the fibers running from one cut face to the opposite cut face.

One of these -¾ thick bonded fiber sheets is cut with a sharp knife at intermittently spaced intervals perpendicular to the cut face of the sheet and .parallel to the fiber direction so as to give slits that penetrate the entire thickness of the sheet. The planes of the slits are generally parallel to each other and vary in length from about % to 3. The slits are spaced from Yi to 2 apart and in a nonregular pattern. The slit sheet is stretched about 10% in a direction perpendicular to the length of the slits so as to expand the width of the slits and, while in this expanded state, one of the faces of the sheet consisting of cut fiber ends is embedded in a layer of rubber adhesive coated onto one face of burlap fabric. The adhesive is allowed to set by drying and there is obtained a backed pile fiber article with the fibers strongly bonded to the backing.

The pile fiber surface of this .backed article is washed with ethanol/water (80/20 by vol.) to remove the terpolymer binder. There is obtained a soft a soft pile fabric suitable for use as a canpet. The areas corresponding to the slits in the sheet had no pile fiber attached to the backing. Pile fiber from adjacent areas partially expanded into the areas of the slits, which resulted in a low pile density and a low pile height in these regions. This gave an attractive pile-textured carpet having a high-low pile effect.