Dimensionally Stable Articles And Method Of Making Same

Abstract

Dimensionally stable articles are produced from heat-treating fabric comprised of multiconstituent filaments prepared from blended fiber-forming polymeric materials having different properties, at least one of the fiber-forming polymeric materials being dispersed as discontinuous fibrils in a lower melting matrix formed by another polymeric material, and natural or synthetic filaments which may or may not have heattreating capabilities. The article is produced by preforming the fabric, during production of the fabric itself or by subsequent operation, and heating the latter to a temperature equal to or above the melting temperature of the multiconstituent matrix material but below that of the dispersed polymeric material, for a time sufficient to impart a shape stabilized property to the multiconstituent filaments and consequently to the fabric article. The multiconstituent filaments are present in the fabric as individual yarn or filament elements in combination with other materials, or are present in a mechanically blended fiber or yarn with other materials. 15 Claims, No Drawings

Description

In a previous development, multiconstituent filaments were produced having a nylon matrix with microfibers of polyester dispersed therein. These filaments (described and claimed in Twilley U.S. Pat. No. 3,369,057, (which patent is hereby incorporated by reference as if fully set out herein) were originally prepared for employment in high strength yarns useful in yarn or cord form as reinforcing strands in elastomeric tires, conveyor belts, seat belts, hoses, and the like. In particular, when used to reinforce tires, the Twilley filaments have a higher tensile modulus than do normal polyamide filaments from the same polyamide, and significantly lower cured strength loss, thereby producing stronger and more durable tires with much less undesirable flat spotting.

In a companion development with this invention, it was discovered that fabric made from multiconstituent filaments could be heated under appropriate conditions to produce novel articles of improved dimensional stability, with good stiffness, moldability, wrinkle resistance, and other desirable properties, yet even after heat-treating the fabric retains its textile appearance. The multiconstituent filaments do not flow or substantially change size as they are fused together during heating, thereby permitting controllable porosity, coloration, texture and other fabric appearance properties combined with the above-mentioned shape stabilization resulting from heat-treating, i.e., the multiconstituent fibers fuse together individually along their lengths, at their cross points, and with any other filaments or yarn having ingredients capable of melting or tacking at the heat-treating temperature. These products have permanent shape retention even after repeated laundering and severe abrasive abuses.

SUMMARY AND OBJECTS

In accordance with this invention, it has been discovered that multiconstituent filaments can be combined with other natural or synthetic filaments to form fabric which can be heat-treated to produce articles similar to those mentioned above yet which can utilize the properties of the various other filamentary materials to vary the final product characteristics and economics. The principal object of the invention is, therefore, to provide novel fabric articles dimensionally stabilized by fusing multiconstituent filaments incorporated in the article in a mechanically blended fiber or in the form of individual filaments or yarns woven, knitted or pressed together with other filaments. Other objects will be apparent to those skilled in the art from the following description and appended claims. As used herein, the term multiconstituent filament means filaments made by inclusion of at least one polymeric material in a matrix of another as discontinuous fibrils, the two materials having melt temperatures at least 10.degree. C. apart such that fibrous structures composed thereof can be heat-treated by application of heat below the melt temperature of one and equal to or above that of the other, the entire filament composition or any component thereof optionally including any secondary material compatible with the heat-treating property of the fabric as a whole such as antioxidants and other stabilizing agents, reinforcing particles, fillers, adhesion promoting agents, fluorescent materials, dispersing agents, and others useful in polymerization, extruding, spinning, fabric forming and shaping, heat-treating and product finishing techniques. By selectively blending these types of fibers desirable properties can be built into a product that can be heat-set to provide permanent shape retention without the aid of bonding agents while maintaining the aesthetic qualities thereof.

DESCRIPTION

Multiconstituent filaments are produced by combining two different thermoplastic polymeric materials preferably, although not necessarily, having melting points approximately 25.degree. C. apart. A major amount of one of the materials is utilized as a matrix in which the other is dispersed. The preferred polymeric materials are nylon 6 (50-90 parts by weight) and polyethylene terephthalate (10-50 parts by weight). The precise nature of these preferred materials and the preferred manner in which they are blended together are fully disclosed in the above cited Twilley patent and reliance on the disclosure therein is made for any details.

In addition to the Twilley multiconstituent materials, other thermoplastic polymers and copolymers alone or in combination may be used such as polyamides, polysulfones, polyphenylene oxides, polycarbonates, polyesters and polyolefins, again with the matrix being present in a major amount and the higher melting dispersion being dispersed in discontinuous fibrils therein, in accordance with the blending principles established in the Twilley disclosure.

Polyesters and polyamides are preferably of the type disclosed in the Twilley patent. Other suitable polyamides are nylon 6/6 (hexamethylene-diamine-adipic acid), nylon 6/10 (hexamethylene-diamine- sebacic acid) methanol- and ethanol-soluble polyamide copolymers, and other substituted polyamides such as the alkoxy substituted polyamides. Suitable polyolefinic materials are polyethylene, polypropylene, poly-1butene, poly-2-butene, polyisobutylene, polystyrene, and similar materials.

In fabric association with the multiconstituent filaments, a wide variety of materials useful in producing fabric may be used, including natural fibers, modified natural fibers and synthetic fibers. For example, useful natural fibers are: animal fur, rabbit hair, wool, worsted, vegetable fibers such as cotton, flax, linen, hemp, jute, kenaf, pineapple fiber, ramie and sisal, and mineral fibers such as asbestos, glass fibers and spun glass. Modified fibers include cyanoethylated cotton, mercerized cotton and non-shrinkable wool. In addition to those specified above, other suitable synthetics are Vinyon-N (manufactured by Carbide and Carlon Corporation by copolymerization of vinyl chloride and acrylonitrile), Saran (a vinyl chloride polymer manufactured by Dow Chemical Company), Orlon, Dacron and Teflon having well-known formulations. Still other examples of materials are polyureas, polyacrilonitrites, polyvinyl alcohol, etc. The only limiting criterion for this particular ingredient is that it occurs as, or may be processed into, a filament which is further capable of withstanding the temperature necessary to fuse the multiconstituent filaments and being included in the structure of a textile material, whether woven, nonwoven, knitted, etc.

The following (example A) is the preferred method of carrying out the invention and illustrates the generally applicable principles hereof. A fiber was prepared according to example 1 of the above-mentioned Twilley patent, i.e., nylon 6 and polyethylene terephthalate, 70 and 30 parts by weight respectively, were heated and blended substantially homogeneously, and spun and drawn so that the final yarn denier was 70 grams per 9000 meters. From this a textured 2 ply/70 denier/16 filament yarn was made. Commercially available nylon 6,6 (70/34 denier/filament) was mixed by the Taslan process to give a 33 percent by weight multiconstituent 67 percent by weight nylon 6,6 yarn which was then knitted into a 1 by 2 rib knit fabric. The fabric was placed over a 6 inch circular hoop with a friction retaining ring and subsequently exposing the fabric to temperatures above the melting point of nylon 6 but below that of the polyethylene terephthalate. The minimum fusion time was approximately 10 seconds at an optimum temperature of 240.degree. C. within the preferred range of 230.degree.-250.degree. C. The resulting data shown below in table I indicates dramatically the effects of heat-treating in terms of stiffness but without loss of fabric appearance. Such dimensionally stabilized fabrics are useful in the production of wall coverings, upholstery for boats, automobiles, planes, in such apparel as hats, shoes, wrinkle resistant garments or portions thereof, and in many other applications.

TABLE I ##SPC1##

Various other methods of combining multiconstituent and non-multiconstituent filaments can be employed. They can be employed as yarn ends or filaments as separate ends in the production of a fabric by known techniques. They can also be formed into a mechanically blended filament by plying two or more different ends together, paralleling two or more ends as one at takeup or coning, entangling two or more different ends either by air or elastrostatic process (either commingle or Taslan) knitting two or more different yarns as one through the same guides, core spinning one yarn with a sheath of another yarn, staple blending different fibers, texturing different ends together or by matting by known techniques.

In another embodiment of the invention, a fabric may be knitted into a fabric having one side predominantly multiconstituent yarn and the other side a nonmulticonstituent.

To illustrate in example A above, instead of utilizing a blended yarn comprised of multiconstituent filaments and nylon 6,6 filaments, these same materials are knitted as separate ends into a Swiss pique fabric using conventional equipment, one side of which is predominantly multiconstituent and the other nylon 6,6. The same can also be done with polyethylene terephthalate or other materials having a higher melting point than the matrix material in the multiconstituent blend, or with a mechanically blended (Taslan for example) yarn such as illustrated in examples A, B or C of table I above in combination with another fiber forming thermoplastic material.

In heat-treating the fabric produced in this manner, fusion on one side but not on the other can be achieved, resulting in a fabric retaining a soft hand on one side but improved shape stability on the other. Such fabrics are useful, for example, in the production of wrinkle resistant fabrics or permanent crease-type garments, and also may be employed in the production of garments requiring a hard or tough exterior or surface. The fabric may be selectively heated where a low melting fiber or yarn is combined with the multiconstituent yarn or blended yarn to avoid fusion of the latter if maximum utilization of the properties of the nonmulticonstituent is desired. For example, heat may be carried out in a mold where only the male or female side is heated while the other is cooled or allowed to remain at a relatively lower temperature during the short period required for fusing the other side, or the fabric may be passed over a heated roll or series of rolls, one of which is heated to a temperature sufficient to fuse the multiconstituent yarn.

In the case of polyester or other yarn having a melting point higher than the multiconstituent matrix in the fabric, it is possible to merely heat-treat the entire fabric as mentioned before with fusion of the multiconstituent component on one side occurring during such heating and maintaining the hand and other physical properties of the polyester portion of the fabric since the melt temperature of the polyester is not reached.

The wrinkle resistance of examples A and B of table I were measured and the results are reported in table II below. As illustrated, the wrinkle resistance of these fabrics remarkably improved.

TABLE II ##SPC2##

Several fabric samples composed of various constructions and fiber blends were heat-treated in accordance with the invention and the results are reported in table III. The data therein illustrates that highly desirable properties can be obtained by varying the fabric construction, blend of materials and heat-treating conditions. Thus, by incorporating selected materials and amounts thereof, products can be tailored to exhibit the desired properties for a given use. For example, the flammable properties of a fabric can be improved by incorporating a nonflammable inorganic fibrous material such as illustrated by examples 17 and 18 of table III. These fabrics were tested in accordance with the standard Fire Resistance of Industrial Fabrics test method AATCC 34-1952 and in both instances were satisfactory. In another embodiment a nonwoven fibrous structure was prepared from a 50/50 staple mixture of 70/30 nylon 6- polyester blend and asbestos fibers. The nonwoven structure was heated to 240.degree. C. for 60 seconds to fuse the nylon-polyester component. The fused structure had excellent strength and did not propagate flame when subjected to the above test method. Additional heating of the structure produced a hard stiff material suitable for use as panelling, etc.

The products of this invention may be employed above or in combination with other articles to form laminates or other types of reinforced articles and products. ##SPC3## ##SPC4##

The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

Claims

1. A dimensionally-stable fibrous structure comprised of a heat-treated, fusion bonded textile material; said textile material being comprised of a blend of (a) a first component of multi-constituent filaments spun from at least two different polymeric materials such that, in a given filament, a first fiber-forming polymeric material defines a matrix and a second polymeric material is dispersed therein in the form of discontinuous fibrils, said matrix comprising at least 50 percent by weight of the filament and having a lower melting point than said dispersed fibrils, and (b) a second component of fibrous material selected from the group consisting of those natural, synthetic or inorganic materials which are capable of withstanding the heat required to elevate the multi-constituent filaments to at least the melt temperature of the matrix thereof; and said textile material having been heat-treated at a temperature in the range above the melting point of the matrix but below the melting point of the dispersed fibrils such that the multiconstituent filaments thereof are set and fusion bonded at least at their cross points without substantial polymer flow, disfiguration, and cross-sectional flattening; whereby a textile appearance is aesthetically retained and said fused textile material is characterized by an enhanced stiffness, shape stability and

2. The product of claim 1 wherein the multiconstituent filaments are melt spun from at least two fiber-forming thermoplastic polymers of which said matrix-forming polymers has a melting index at least 10.degree. C. lower

3. The product of claim 2 wherein the said matrix-forming polymer comprises

4. The product of claim 3 wherein the multiconstituent filaments comprise

5. The product of claim 4 where polymer forming the matrix of said multiconstituent filaments is selected from the group consisting of

6. The product of claim 4 wherein the dispersed fibrils are formed from a polymer selected from the group consisting of polyolefins, polyamides,