MXPA98006532A - Fibers of transversal arbitrary cutting and process of production of mis - Google Patents

Abstract

The present invention relates, in general, to the spinning of fibers and, in particular, to a process of spinning fibers of more than one component in the cross section and to the fibers produced by

Description

FIBERS OF TRANSVERSAL ARBITRARY CUTTING AND PROCESS OF PRODUCTION OF THE SAME FIELD OF THE ART The present invention relates, in general, to the spinning of fibers and, in particular, to a process of spinning fibers of more than one component in their cross section and to the fibers produced by this means.

BACKGROUND Various types of fibers with two or more components in their cross section (ie, multicomponent fibers) are known in the art, as are their production processes. Examples of these fibers and production processes are set forth in U.S. Pat. 4,233,355 and 4,460,649. Multicomponent fibers have been used to generate micro or ultra-fine filaments (see, for example, U.S. Patent Nos. 4,233,355, 4,966,808, 5,124,194 and 5,366,804). The fibers can be separated into their components using mechanical or chemical means (for example, solvents). In U.S. Pat. 4,233,355, for example, microfibers are generated from multicomponent (composite) fibers by the selective dissolution of one of the components of the composite fiber using a solvent in which the micro-fibrous component is relatively insoluble. The technique does not include a description of a method of producing a fiber of almost any shape in its cross section from a composite fiber having a preselected relative array of components of different solubility in a given solvent. The present invention offers this process.

OBJECTIVES AND COMPENDIUM OF THE INVENTION A general objective of the invention is to offer a process of producing a fiber of almost any shape in its cross section. A specific object of the invention is to provide a process for producing a fiber of predetermined transverse shape from a composite fiber that includes at least two components that have different solubility characteristics and that are found in a selected relative array. Another object of the invention is to provide a composite fiber comprising at least two components with different solubility characteristics (for example water solubility characteristics). The aforementioned objectives are met by a composite fiber having two or more components in its cross section that comprises different materials (for example, polymers), one of these materials being more soluble in a specific solvent (for example, water) than the other. The components are present in a predetermined relative arrangement so that, with the solution of the component more soluble in the solvent, the relatively insoluble component remains as a fiber with a predetermined shape in its cross section. Other objects and advantages of the invention will be apparent from the following description.

BRIEF DESCRIPTION OF THE DRAWINGS Figures 1A-E show cross-sectional views of the fibers comprising the components having different solubility characteristics. Figures 2A-E show cross-sectional views of the fibers resulting from the dissolution of the soluble component of the composite fibers shown in Figure 1.

DETAILED DESCRIPTION OF THE INVENTION The present invention relates, in one embodiment, to a process for preparing fibers of different cuts, which includes cross sections not easily obtainable using the techniques of spinning of conventional melts. The process consists of preparing a fiber that contains at least two components with different solubility characteristics in a given solvent. The components are placed in the composite fiber one in relation to the other so that, with the dissolution of one of the components in the solvent, the most insoluble component in this solvent remains as a fiber with a desired shape in its cross section. Depending on the orientation of the component materials, it is possible to achieve a variety of cross sections of the composite fiber and forms of the composite fiber (see, for example, Figures 1 and 2). By 'removing the most soluble or dispersible component, it is possible to obtain fiber forms of the component which are difficult to obtain by direct extrusion due to the effects of surface tension which otherwise tend to' round off 'the characteristics of the cross section after the extrusion Although one can take advantage of the different solubility characteristics with respect to a variety of solvents (including polar solvents such as water, acetone, alcohols, dimethyl formamide (DMF), methyl ethyl ketone (MEK) and cellosolves), the present invention is will describe in detail with respect to the different water solubility characteristics (the terms "water-soluble" and "water-insoluble" are then used simply for purposes of clarity). Furthermore, it will be appreciated from reading the following that the multicomponent fiber can include a plurality of components with different solubility characteristics. However, the following description will focus on a composite, two-component fiber. The production of the composite fiber of the invention can be obtained using conventional spinning techniques (e.g., melt spinning techniques). The water-insoluble component can be supplied to the apparatus for spinning the fiber at the same time by supplying the water-soluble component to this apparatus. In the spinning apparatus, the water-soluble and water-insoluble components are arranged in a predetermined relative arrangement to obtain a selected cross-sectional shape of the water-insoluble component. The water-soluble and water-insoluble components are extruded into the spinning apparatus in the predetermined arrangement. The water-soluble component is removed by dissolving in an aqueous solution so that the water-insoluble component remains in the selected cross-sectional shape adopted as a result of the presence of the water-soluble component in the spinneret. The components of the composite fiber (for example, component polymers) that can supply the spinning apparatus, for example, through a transfer tube, using conventional methods, including pumping with positive pressure. The thermoplastic polymer components are melted at suitable temperatures (e.g., about 10 ° C to 75 ° C more than the melting point of the polymer) before pumping. Independent supply mechanisms can be used for each component. Various methodologies can be used to selectively arrange the components of the composite fiber in the spinning apparatus in a predetermined relative array. Particularly advantageous is the method described in U.S. Patent 5,162,074 using distributor plates in which distributor flow paths are engraved on one or both sides to distribute the polymer components to suitable locations in the die orifices. The etching process allows the distribution path to be small enough to facilitate the emission of multiple continuous streams of the polymer component in the axial direction towards each inlet hole of the die orifice. The polymer components can be extruded through the holes in the row, which. They can be in a variety of ways. In the case of polymers spun in the molten state, the extrusion may be to a cooling chimney to form filaments cooled by a flow of gaseous medium, such as air, which hardens the filaments. When that uses dry spinning, the cooling conditions are selected to effect the removal of the solvent. The use of hot air or hot, dry air is common. As in the previous, air conditioning flows over the filament when the filament passes through the cooling chimney. (The composite fibers of the invention may also contain an insoluble component of the melt-spun core (e.g., a polypropylene melt) and a sheath component soluble in polymer solution (e.g., a solution of polyvinylpyrrolidone (PVP) in ethanol). These composite fibers do not need to be subjected to a solvent removal step prior to dissolution of the soluble component (eg, PVP). After extrusion the water soluble component is removed. Removal can be effected, for example, by passing the fiber (eg, after cooling (or removal of the solvent)) through a bath containing a solvent in which the water-soluble component is soluble (eg, water) under conditions such that solubilization / dissolution is carried out. In an alternative mode, the fiber can also be processed, for example, into short-sized fiber, and then be treated as bulk material, as for example in a bulk tinsion operation. The fiber and yarn can also be processed into final products and the finished products can then be treated with solvent (for example water) to remove the soluble component. The latter method can result in a woven or knitted fabric or floor coverings having a fiber structure, after dissolution of the water soluble component, which may not be possible to produce without dissolution. The fibers produced according to the present invention can be processed, for example, using conventional techniques of drawing, texturing, finishing, etc., and can be colored using pigments or dyes. The insoluble component, for example, may include heat or light stabilizers. End-use applications of the fibers of the invention include common textile applications in clothing, household waxes or industrial products in which the cross-section of the resulting fiber improves performance, properties or aesthetics. The transversal cuts of the fiber that can be obtained by the invention can favor the tactile and comfort properties, modify the properties of luster and reflection of light, favor the hiding power, favor the absorbent and braided power and modify the flexural modulus and ripple capacity.

Suitable insoluble component materials include melt-spun polymers, for example, nylon 6 and 66, polyester, polyethylene and polypropylene. Suitable soluble or dispersible components include copolymers thereof as well as soluble homopolymers such as polycaprolactone and polyethylene oxides. The insoluble or non-dispersible components can be solubilized with comonomers containing solubilizing or dispersing functional groups, such as vinyl, sulfonate, phosphonate or ethoxylate groups. In a specific embodiment of the invention, nylon or polyester is used as the water-insoluble component and a meltable-meltable polymer such as that described in U.S. Pat. 3,846,507 (for example, water soluble polyamide as described therein) can be used as the water soluble component. According to this embodiment, the nylon 6 with a sulfonated polyamide soluble in water or in solvent so that the insoluble nylon 6, for example, is extruded as the core component and the soluble sulfonated polyamide is the sheath component. These components can be oriented so that a composite fiber having, for example, a half dumbbell shaped core grafted onto a fiber with a rounded cross section can be produced. Because the total cross section is round, it will tend to maintain its shape and will not deform after extrusion. After removal of the soluble component from the composite fiber using, for example, water or steam, the inner core is preserved in the form of a half-dumbbell as the final fiber. Any of a variety of alternative internal core structures can be achieved according to the invention (see, for example, Figures 2A-2E). The following non-limiting examples describe certain aspects of the invention in greater detail.

EXAMPLE Nylon 6 and sulfonated nylon bits were "cast in separate single-screw extruders and pumped by separate gear pumps into a two-component row.The row consists of filters and distribution plates that separately send the polymers to the rear hole. The row contains a number of holes that depend on the desired number of fibers in the yarn, the desired performance, etc. After extrusion, the fiber passes through a cooling zone in which the cold air solidifies the molten polymers.The filament then passes over a series of guides submerged in a bath of hot water.After bathing, the filament is textured with air or steam and rolled or cut into small fibers.

The person skilled in the art will appreciate from a reading of this description that various changes in form and detail can be made without departing from the true scope of the invention.

Claims (17)

1. A process for preparing a Figure • consisting of: a) supplying a first polymer or spinnable polymer solution to an apparatus for spinning fibers; b) supplying at the same time to the apparatus a second polymer or spinnable polymer solution, cohable with the first polymer or first polymer solution, wherein the first polymer or the first polymer solution is more soluble or dispersible in a solvent than the second polymer or the second polymer solution; c) in the fiber spinning apparatus, arranging the first polymer or the first polymer solution and the second polymer or the second polymer solution in a predetermined relative arrangement to achieve a selected cross-sectional shape of the first polymer or the first polymer solution; d) extruding from the spinning apparatus a filament of the first polymer or the first polymer solution and the second polymer or the second polymer solution in the predetermined relative array; e) contacting the filament resulting from step (d) with the solvent under conditions such that substantially all of the second polymer or the second polymer solution is dissolved or dispersed in the solvent and the first polymer or first polymer solution remains in the form of Selected cross section.

2. The process of claim 1, wherein the solvent is a polar solvent.

3. The process of claim 2, wherein the solvent is water, a ketone, an alcohol, an ether, an ester or an amide.

4. The process of claim 3, wherein the ketone is acetone or a methyl or ethyl ketone.

5. The process according to claim 3, wherein the amide is dimethylformamide.

The process of claim 1, wherein the first polymer is supplied to the apparatus for spinning fibers in step (a).

The process of claim 6, wherein the first polymer is a meltable-meltable polymer.

The process of claim 7, wherein the first polymer is polyester nylon, polyethylene or polypropylene.

The process of claim 1, wherein the second polymer is supplied to the spinning apparatus in step (b).

10. The process of claim 9, wherein the second polymer is a meltable meltable polymer.

11. The process according to claim 10, wherein the second polymer is a copolymer of nylon, polyester, polyethylene and polypropylene. The process according to claim 10, wherein the second polymer consists of comonomers containing solubilizing or dispersing functional groups. The process according to claim 12, wherein the functional groups are vinyl, sulfonate, phosphonate or ethoxylate groups. The process according to claim 10, wherein the second polymer is a soluble homopolymer. 15. The process according to claim 14, wherein the homopolymer is a polycaprolactone or a polyethylene oxide. 16. The process of claim 6, wherein the second polymer is supplied to the spinning apparatus in step (b). 17. The process of claim 16, wherein the second polymer is a meltable meltable polymer. 1 V, í t? 1 * of nylon, polyester, polyethylene or polypropylene. 19. The process according to claim 18, wherein the second polyester comprises comonomers comprising solubilizing or dispersing functional groups. The process according to claim 17, wherein, the second polymer is a soluble homopolymer. The process of claim 20, wherein the homopolymer is a polycaprolactone or a polyethylene oxide. 22. The process of claim 21, wherein the functional groups are vinyls, sulfonate, phosphonate, or ethoxylate groups.