NON-WOVEN FABRIC AND METHOD FOR PRODUCING SAME

Abstract: A non-woven fabric suitable for clothing manufacture, comprises a fiber web substantially formed of a continuous filament of a synthetic fiber, wherein a plurality of weakened portions in a form of a scratch or a crack are distributed on the filament constituting at least one surface of the fiber web. Some of the weakened portions are broken to form free ends, some of which are projected from the fabric surface to form a short fluff, and some, of the remaining ends are embedded in the interior of the fiber web and entangled with the filament. The weakened portions of the filament are provided by nip­ ping the fiber web between a pair of rollers, at least one of which has a rough surface formed of a plurality of prominen­ ces of hard particles. A punching treatment of the fiber web after the weakened portions has been imparted is effective for breaking the filament to form short fluffs on the fabric surface and for entangling the filaments with each other. A resin treatment before the punching treatment is also favorable.

Description: 1. Field of the Invention The present invention relates to a unique non-woven fabric and a method for producing the same, particularly, to a non-woven fabric formed of a continuous filament of synthetic fiber, having a structure and an appearance as if staple fibers are mixed therewith and having an excellent softness and pilling resistance suitable for high class clothing, and a method for producing the same. 2. Description of the Prior Art In the past, a typical non-woven fabric was a felt utilizing a milling property of wool. Since then, many non-woven fabrics formed of a web of synthetic staple fibers or a layered sheet of synthetic filament fibers having a non-milling property have been proposed, which web or sheet is punched by needles or water jets to cause the composing fibers to become entangled. Some of these non-woven fabrics are used as a final product without further treatment, and the others are post-treated to strengthen the mutual entanglement or bonding between fibers by resin impregnation or by press-heating. The production system using the staple fiber web as a starting material has an advantage in that fibers are easily entangled by needle-punching or the like. This system, however, has a drawback in that a web having a uniform thickness is not easily produced from a lump of staple fibers through a carding engine, especially when the fibers are long staple fibers of ultra-fine denier suitable for clothing manufacture. In this case, the resultant web has an uneven quality and many cloudy portions where the fibers are not fully separated from each other. Thus, this problem constitutes a bar to the production of a non-woven fabric having light weight, excellent softness and uniform thickness. Especially, when the fiber web is resin-coated, a resin membrane is unevenly formed on the web surface, and thus the reinforcement effect of the resin-coating can not be attained. To improve the softness of the non-woven fabric for the manufacture of clothing, various methods have been proposed. For example, a fiber web is prepared by a composite fiber having an island-in-sea type structure and, thereafter, the sea component of the fiber is removed so that the island component remains as an ultra-fine fiber, or alternatively, a web is prepared from a splittable conjugated fiber composed of different kinds of polymers and is post-treated to divide the conjugated fiber into the individual components. These techniques, however, require a sophisticated spinneret structure for extruding such a composite fiber, which tends to make production management difficult. Moreover, an additional process is required for obtaining the component fiber from the original fiber. Thus, the process becomes complicated and the production cost becomes very expensive. According to a system for the production of a layered web sheet from a continuous filament fiber spun directly from a spinneret, usually referred to as "a spun bond system", as is known from GB-A-1304732 an ultra-fine fiber such as that one having a 0.55 dtex (0.5 denier) is usable because the fiber thickness has little influence on the evenness of the resultant fiber web relative to the former system using a staple fiber web prepared from a carding engine. Even in this system, however, the resultant non-woven fabric has a drawback in that the fibers in the fabric are liable to be displaced in the web when an external force is applied, since the migration and the mutual entanglement of the fibers are not enough even after they are subjected to powerful water-jet punching during the web forming process. This relatively loose structure of the fabric results in a tendency toward pilling or napping on the fabric surface and is one reason why the non-woven fabric obtained by the latter system is not utilized in the manufacture of clothing. In general, to avoid the abovesaid pilling or the like, the fiber web forming the non-woven fabric is impregnated with a resin or is subjected to a heat-adhesion treatment to reinforce the bonding between the fibers composing the web. The fabric thus obtained, however, tends to lack the desired soft touch and to lose air-permeability, and in addition, a paper-like, annoying sound is generated when touched. These are fatal drawbacks for clothing manufacture, even though usable for industrial purposes. SUMMARY OF THE INVENTION It is a primary object of the present invention to eliminate the above drawbacks of the prior art and to provide a unique non-woven fabric and a method for producing the same, which fabric is highly resistant to "pilling" or "napping" and has an excellent weight reduction, drape, resiliency and touch suitable for clothing manufacture. It is a second object of the present invention to provide a non-woven fabric and a method for producing the same, which fabric has a further improved resistance to "pilling" or "napping" while retaining the other above favorable properties by a resin treatment using a lower volume of resin. According to a first aspect of the present invention, there is provided a non-woven fabric suitable for clothing manufacture, comprising a fiber web formed substantially of continuous filament of synthetic fiber, wherein a plurality of weakened portions provided by scratches or cracks are distributed along filament regions defining at least one surface of the fiber web; some of the weakened portions being broken to form free ends; some of the free ends projecting from the fabric surface to form naps, which may be defined by short fluffs, and some of the remaining ends being embedded in the interior of the fiber web and entangled with the filament. According to a second aspect of the present invention, there is provided a method for producing the abovesaid non-woven fabric which method comprises collecting continuous filament of a synthetic fiber, to form a fiber web and subjecting the fiber to a weakening treatment in which the fiber web is nipped between a roller system or a plate system, at least one element of the system having a rough surface provided by a plurality of particles of hard material so that weakened portions are imparted to filament regions defining at least one surface of the fiber web, and a punching treatment, in which the fiber web is punched so that filament parts are entangled with each other. If necessary, a resin may be coated on, or impregnated in the fiber sheet at an appropriate stage after the fiber web is formed. BRIEF DESCRIPTION OF THE DRAWINGS Other objects and advantages of the present invention will be apparent from the description of the preferred embodiments of the present invention illustrated in the attached drawings, wherein: Fig. 1 is a diagrammatic perspective view of the structure of a non-woven fabric according to present invention; Fig. 2 is a diagrammatic perspective view of the structure of a non-woven fabric according to the prior art; Fig. 3A is a diagrammatic perspective view of the structure of the non-woven fabric shown in Fig. 1, after complete impregnation of a resin; Fig. 3B is a diagrammatic perspective view of the structure of the non-woven fabric shown in Fig. 1, after partial impregration of a resin; Fig. 4 is an enlarged sectional view of the structure of the non-woven fabric shown in Fig. 3A; Figs. 5A, 5B and 5C are diagrammatic side views of process arrangements for producing a non-woven fabric according to the present invention, respectively; Figs. 6A through 6D are cross sections of various conjugated composite fibers suitably utilized for the present invention, respectively; Fig. 7 is a microscopic photograph showing a surface of a starting fiber web having no weakened portions imparted by the present invention; and Figs. 7A through 7D are microscopic photographs showing weakened portions and broken ends of fibers composing the non-woven fabric of the present invention. DESCRIPTION OF THE PREFERRED EMBODIMENTS A non-woven fabric according to the present invention is mainly formed of a continuous filament spun from a fiber-forming polymer, such as polyethylene-terephthalate, polyamide, polyacrylonitrile, polyethylene, polypropylene, polysulfide-polyimido, or polybutyleneterephthalate, or a modified polymer thereof. The filament may be either a usual mono-component fiber or a multi-component composite fiber such as an island-in-sea type composite fiber or a splittable type conjugated fiber. Fibers of various cross sections may be used, including the usual circular or a non-circular sections. The abovesaid multi-component composite fiber includes a combination of different kinds of polymers such as polyethylene-terephthalate and polyamide, and a combination of polymers of the same kind having different intrinsic viscosities, of a regular polymer and a copolymer, or of polymers with and without additives. The typical cross sections of the composite fiber composed of multi-components are illustrated in Figs. 6A through 6D, in which Fig. 6A shows a side-by-side type (conjugated type), Fig. 6B an orange type, Fig. 6C an islands-in-a-sea type, and Fig. 6D a split table type. These composite fibers can be divided into individual components, each of which forms a generally very fine continuous filament. This splitting process is carried out, for example, by a chemical treatment in which one component of the composite fiber is dissolved by a certain agent, or a physical treatment in which pressure or punching is applied to the fiber to separate the individual components from each other. When using the above splittable composite fiber as a material filament, a resultant non-woven fabric according to the present invention has a very soft touch, although the present invention is not limited to the use of this type of filament. That is, a denier of the individual continuous filament applicable to the non-woven fabric according to the present invention can be selected from a wide range of from 0.01 denier to a denier of several multiples of ten, but the most suitable range is from 0.05 denier to 5 denier for the purpose of clothing manufacture. The fiber denier should be selected by taking the final property of the non-woven fabric into account. For example, if a soft touch is desired in the final product, an islands-in-a-sea type composite fiber having individual island components of from 0.01 denier to 1.0 denier distributed in a sea component is preferably utilized, and the sea component removed after the grey non-woven fabric has been formed. Alternatively, the splittable composite fiber having individual components of from 0.05 denier to 5.0 denier is advantageously adopted, which fiber is split into individual micro-filaments after the grey non-woven fabric has been obtained. If the usual plain filament fiber composed of mono- or modified polymer is utilized, the thickness thereof should be 0.1 denier to 5 denier. Especially, when an ultra-fine fiber of, for example, 0.01 denier to 0.05 denier, is utilized, a preferable non-woven fabric having good resistance against "excess napping" can be obtained, because the fiber density in a fiber web forming the fabric can be increased to strengthen the entanglement between the fibers. Further, resistance against "pilling " is also improved, because fibers emerging on the fiber surface are easily broken without accompanying drag-out of the internal fiber when an external force is applied thereto. On the contrary, if the fiber denier becomes larger to an extent such that it exceeds, for example, 5 denier or more, the softness of the resultant fabric is adversely influenced. A non-woven fabric according to the present invention is first prepared by a layered sheet of fiber web formed of the aforesaid continuous filament, which web is then subjected to a weakening treatment in which the filament constituting at least one surface of the sheet is imparted with weakened portions each provided by a crack or a scratch. The filament is to be broken at some of the weakened portions to form free ends, which are sometimes embedded in the interior of the web due to migration and sometimes project from the surface of the web as a favourable nap. The non-woven fabric according to the present invention may be produced from a starting fiber web formed mainly or entirely of continuous filament yarn by a unique method comprising a weakening treatment and a punching treatment. Regarding the weakening treatment, the fiber web subjected to this weakening treatment may be either a simple layered web without fiber bonding or a provisionally bonded web. The roller system or plate system utilized for the weakening treatment preferably consists of a pair of elements in the form of a roller or plate, each of which elements is engaged with the other to nip the fiber web therebetween. For continuous processing of the fiber web, the roller system is most preferable. At least one element of the pair has a rough surface for imparting a crack or scratch to the filament. This rough surface may be provided by an emery cloth or an emery paper. Alternatively, hard particles selected from a group including diamond, silicon carbide, boron carbide, crystalline aluminum oxide, zirconium oxide, garnet, quarz artificial diamond, artificial sapphire, silicon nitride, ceramics, alumina, titanium oxide, or glass may be directly coated on the element surface. In another aspect, the element may be molded from a material containing the above hard particles, which is buffed to form a plurality of prominences on the surface of the element. This rough surface element is pressed against one side or both sides of the web to form weakened portions on the filaments existing on the web surface. The roughness of the rough surface should be in a range of from 1 µm through 5000 µm in average particle diameter, according to the study of the present inventor, and preferably from 50 µm through 500 µm, which range corresponds to an emery grade of from #40 to #600. The nipping pressure should be varied in accordance with the physical properties of the fiber constituting the fiber web. The pressure is selected so that, when the filament is stretched during a subsequent punching treatment, the filament can be broken at at least some of the weakened portions. In other words, the intensity of the punching treatment should be such that the abovesaid filament breakage occurs. It must be noted that, according to the present invention, the weakened portion of the filament is not formed by "shearing" or "tearing", as in the case of a raising machine, but mainly by "cracks" or "scratches" as stated before and as shown in Figs. 7A through 7D. The weakening treatment may be carried out immediately after the web is formed (in this stage, the web has substantially no mutual entanglement), or after a provisional (preliminary) entanglement is imparted. In this regard, the provisional entanglement of the web fiber may be provided by, for example, calendering, heat-embossing, needle punching, or water jet punching . The combination of the punching treatment and the weakening treatment may be repeated twice or more. In another aspect, after the preliminary punching treatment, a resin may be impregnated in the fiber web and, thereafter, the weakening treatment may be repeated. Alternatively, after the punching treatment, a resin may be coated on or impregnated in the web and, thereafter, the weakening treatment may be carried out, which may be followed by a second punching treatment. The weakening treatment is usually carried out at room temperature, but it may be possible to heat the pressing roller system or to heat the fiber web itself prior to the weakening treatment. The fiber web may be treated in a wet condition or a dry condition. The punching treatment includes needle-punching and water jet-punching, of which the latter is most preferable because the product properties such as softness, can be easily controlled. As stated before, the nipping pressure, by which the rough surface element is pressed against the web surface, is selected so that the weakened portions imparted can be easily broken by the water jet-punching. In the roller system, the nipping pressure is preferably in a range of from 0.01 kg/cm through 500 kg/cm along a nip length of the roller. The broken end of the filament caused by the punching migrates to the interior of the web from the punched surface together with the water jet or the needle and is entangled with the interior filament or filaments. Some of the broken ends emerge on the back surface of the web opposite to the punched surface, whereby a favourable nappy non-woven fabric can be obtained. The thus obtained non-woven fabric may be used as a final product according to the present invention, or may be used as an intermediate product which will be a final product after being subjected to a post-treatment. Regarding the resin-treatment effective for increasing the inter-fiber bonding, an impregnation or coating process using, e.g. polyurethane resin is most popular, by which the touch and functional properties of the non-woven fabric can be improved to a great extent. Other than polyurethane, the following material may be utilized: polyvinyl alcohol, nitrile-butadiene rubber, styrene-butadiene rubber, ethylene-propylenecopolymer, chlorosulfonated polyethylene, silicone resin, fluorine resin, polyvinyl acetate, polyvinyl chloride, polyamide, acrylic ester, amino acid, polyolefin, copolymer of polyethylene, and polyvinyl acetate. Instead of the resin treatment, a stitch-bonding or a fusion-bonding of the starting fiber web may be applied for enhancing the inter-fiber bonding. According to the punching treatment after the resin coating or impregnation, not only are the weakened portions of the filament broken but also the resin layer is perforated with a plurality of micro-pores, whereby the non-woven fabric thus obtained has an improved appearance and touch as well as an excellent air-permeability, just like a fabric made from staple fibers. Where the resin treatment uses polyurethane, solidification of the resin may be carried out by either a wet system or a dry system. According to the former system, since the solidified resin forms a micro-porous honey-comb structure due to foaming, softness of the resultant fabric is improved. On the other hand, according to the latter dry system, a thinner membran of the resin can be formed on the surface of the fabric because the solvent of the resin is evaporated in the air directly from the surface of the fabric. Thus, the resin treatment enhances the mutual bonding between the filaments and the resilience of the fabric, which minimizes the residual elongation of the non-woven fabric and improves the durability of clothing manufactured from the fabric. The amount of the resin to be impregnated in the fabric is preferably such as to give a fabric/resin weight ratio in a range of from 99/1 to 20/80, more preferably, from 95/5 to 70/30, if it is desired to maintain the softness of the grey fabric. If the amount of the resin is less than 1%, an improvement of the resistance against pilling or napping cannot be attained, although the softness of the fabric is not changed. On the contrary, if the resin ratio exceeds 80%, the touch becomes harsh and the fabric is unsuitable for clothing manufacture. Usual finishing treatments may be carried out in the final stage of processing, which finishing treatments include, for example, calendering, embossing, buffing (raising), and creasing. These treatments may be applied to the fabric independently or in combination. Of course, these treatments may be combined with the abovesaid resin treatment. Calendering serves to improve the smoothness and luster of the surface of the fabric, and is effective for increasing the warmth-keeping property because the number of voids between the filaments is decreased. Embossing serves to impart surface variations of colour, touch, or luster to the fabric. Buffing (raising) enhances the plush-like effect and improves the touch of the fabric surface. Finally, creasing forms various wrinkles on the fabric surface, which can further the fashionability of the fabric. The non-woven fabric according to the present invention is mainly constituted by a continuous filament fiber but may include a staple fiber as a small part thereof. The weight of the fabric is preferably in a range of from 10 g/m² through 300 g/m², more preferably, from 10 g/m² through 50 g/m². The non-woven fabric according to the present invention has an excellent pilling resistance exceeding a third grade defined in a five-hour test by a method developed by I.C.I. In this regard, the I. C. I. method is widely used in the textile industry for estimation of pilling tendency of a knit or a woven fabric, in which pilling resistance is defined by grades ranging from 1 to 5, the higher the grade, the greater the pilling resistance. This method is described in detail in JIS (Japanese Industrial Standard) L 1076, method A. In the present invention, a resistance against excessive napping is also estimated from the appearance of the test pieces. Filling results firstly from an entanglement between fluffs on the surface of the fabric, which grows to an undesirable nappy surface, then develops to a so-called pill because the interior fiber connected to the nap is dragged out of the interior of the fabric without breakage. Pilling should be avoided because it degrades the appearance of the fabric. In particular, since the non-woven fabric has a relatively loose fiber structure compared to a knit or a woven fabric formed of threads, the napping or pilling is liable to be generated in a shorter period compared to the latter. In addition, the non-woven fabric formed from a filament has an inferior mutual fiber entanglement to that formed from a staple fiber because it is difficult for the filament to migrate in to the fabric, whereby once the adverse nap is formed on the fabric surface, the filament is withdrawn substantially in an endless manner from the interior of the fabric to form larger pills. To solve the above problem, according to the present invention, the filament is imparted with the weakened portions so that it can be broken when the stretching force is applied thereon during the formation of pilling. The resin treatment is also effective for increasing the inter-fiber restraint force. With reference to Figs. 1 to 4, the structural features of the non-woven fabric according to the present invention will be described in more detail relative to the conventional non-woven fabric. First, the structure of a conventional non-woven fabric 2 formed from a continuous filament is explained with reference to Fig. 2, in which a continuous filament 3 constitutes relatively parallel fiber bundle portions 3-a, cloudy fiber portions 3-b, loop-like migrated fiber portions 3-c caused by water jet-punching, and micro-pores 3-g provided by the water jet-punching. According to this structure, the cloudy fiber portions 3-b on the both surfaces are very unstable and the number of the migrated fiber portions 3-c is very few. Figure 1 shows an example of the structure of the non-woven fabric 1 according to the present invention. The differences between this fabric 1 and that shown in Fig. 2 are that with fabric of Figure 1, a plurality of weakened portions 3-d are distributed on one surface of the fabric 1, and that fluffs 3-e provided by the breakage of the filament 3 by water jet-punching and migrated fiber portions 3-f having free ends are mixed. In Figs. 3A and 3B, the non-woven fabric 1 is impregnated with a resin 4. Figure 4 illustrates an enlarged model of the structure of the non-woven fabric according to the present invention obtained by a combination of provisional punching by water jet, resin treating, weakening and, again, substantial punching by water jet. The resultant non-woven fabric 5 is provided with the weakened portions 3-d of the filament 3, the fluffs 3-e, and the micro-pores 6 randomly distributed over the fabric surface. According to the present inventor's study, the number of micro-pores 6 is preferably in a range of from 1/cm² through 300/cm². If this value exceeds the lower limit, the air permeability of the non-woven fabric becomes poor, and on the other hand, if the upper limit is exceeded, the physical strength of the fabric is decreased and the durability thereof is degraded. Figures 5A to 5C illustrate one of the preferred embodiments of the process for obtaining the non-woven fabric 1 according to the present invention shown in Fig. 1. As shown in Fig. 5A, a continuous filament 3 spun from a spinner 7 is withdrawn by means of an ejector 8 while subjected to a drawing operation. and is collected on a net conveyer 10 to form a fiber sheet 11 after impinging on a baffle plate 9. Then, the fiber sheet 11 is wound up on a take-up roll 14 as a starting fiber web 13. As shown in Fig. 5B, the fiber web 13 is subjected to a high pressure water jet from a water-jet punching unit 17 while being conveyed by a net conveyer 18, whereby a preliminary punching treatment is carried out. The thus-obtained preliminarily entangled non-woven fabric 20 is wound up on a take-up roll 21 after dehydration by a squeezing roller 29. This non-woven fabric 20 is continuously fed into a nip zone between a rough surface roller 23 having a plurality of protrusions formed of hard particles on the surface and a smooth surface roller 24, as shown in Fig. 5C, whereby weakened portions are imparted to one side of the fabric 20 in contact with the rough surface roller 23. The thus-obtained non-woven fabric 25 having the weakened portions is introduced again into a punching unit 27 having substantially the same function as the aforesaid water-jet punching unit 17 while being carried by a net conveyer 28, by which the substantial entanglement treatment is carried out, and is finally wound up on a take-up roll 31, after passing through a squeezing roller 39, as a final non-woven fabric 1 according to the present invention. It should be noted that the filament 3 constituting the non-woven fabric is broken to form free ends, some of which project outside to form the fluffs 3-e, and others are embedded in the interior of the fabric during the substantial entanglement treatment shown in Fig. 5C. The process shown in Fig. 5C may be repeated twice or more. Further, in the abovesaid process, the intermediate take-ups of the non-woven fabrics 13 and 20 may be eliminated, that is, the process can be carried out continuously without interruption. Alternatively, a buffing (raising) treatment may be included in the process for example, prior to the entanglement treatment. If it is desired to obtain the non-woven fabric shown in Fig. 4, the resin treatment may be incorporated in the process prior to the substantial entanglement treatment shown in Fig. 5C. As described above, according to the present invention, although the starting material of the fabric is mainly a continuous filament fiber, the resultant fabric has a soft touch and an improved resistance against pilling, the same as a fabric composed of a staple fiber, while maintaining the desirable properties of the fibrous material such as a light weight, a warmth-keeping property, drapeability, and resiliency, which are inherent in a non-woven fabric. Thus, the present invention provides a novel non-woven fabric that can be utilized for high class clothing manufacture. An additional effect is obtained from the weakening treatment when a splittable filament such as an island-in-sea type conjugated fiber is used. Due to the cracks or scratches on the filament caused by the weakening treatment, a considerable amount of the conjugated fiber is liable to divide into a sea component and an island component during the succeeding entanglement treatment, by which the sea component will be easily dissolved when the resultant fabric is subjected to a sea component removing treatment for obtaining the island component only. Further, due to this fiber splitting, the individual island components can be entangled even in a grey fabric, whereby the entanglement degree is improved. On the other hand, in the conventional method, since such a preliminary fiber split does not occur, the fibers are entangled while retaining a bundle form including both the sea component and the island component. In other words, the entanglement degree becomes poor. According to the above high entanglement degree, the non-woven fabric of the present invention needs a less amount of resin even if the resin treatment is necessary, which enhances the softness and air-permeability of the fabric. Regarding the air-permeability, the non-woven fabric shown in Fig. 4 obtained by a series of steps of the first punching treatment of the starting fiber web, the resin-treatment, the weakening treatment, and the second punching treatment is particularly excellent in this property. The effects of the present invention will be more apparent from the following examples: In the Examples, the estimation of test pieces was carried out according to the procedures defined in the following JIS (Japanese Industrial Standard): 1. Filling resistance: L 1076, Testing Method for Pilling of Woven Fabric and Knitted Fabric, Test A (I.C.I method); 2. Stiffness: L 1079, Testing Method for Stiffness of Woven Fabric and Knitted Fabric, Test A (45° cantilever method); 3 Air permeability: L 1096, Testing Method for Fabrics, Testing Method for Air Permeability, Test A. Example 1 A fiber web having a weight of 50 g/m² was prepared by a filament fiber of polyamide having a thickness of 0.5 denier spun at a high rate by the process shown in Fig. 5A. The fiber web was subjected to a preliminary punching treatment by means of the process shown in Fig. 5B, wherein the nozzle diameter was 0.14 mm, the nozzle pitch was 1.1 mm and the water pressure was 40 kg/cm². Then, one surface of the fiber web was subjected to a weakening treatment using a pair of pressing rollers, one of which had a rough surface provided by an emery cloth of #100 mesh, under a nipping pressure of 55 kg/cm² along a length of the roller. This treatment was repeated twice. Thereafter, the weakened surface of the fiber web was subjected twice to a substantial punching treatment by using the same water-jet punching unit as before under water pressures of 60 kg/cm² and 70 kg/cm², respectively. This punching treatment was repeated once on the other surface of the fiber web under a water pressure of 60 kg/cm². These punching treatments were carried out at a processing speed of 1.7 m/min. The thus-obtained non-woven fabric was subjected to a resin treatment after drying, in which polyurethane resin was impregnated in the fabric with the weight ratio of fabric/resin = 78/22. Finally, both surfaces of the fabric were subjected to a calender treatment and to a finishing treatment after dyeing. The resultant fabric had a rich softness due to fluffs and had a mild luster as well as a good resiliency. For the comparison of pilling resistance, a blank was prepared by the same process as before except for the elimination of the weakening treatment. The test results were listed on Table 1. As apparent from Table 1, the non-woven fabric showed a satisfying practical performance compared to the conventional product. Test Period (hour) Pilling Resistance Present Invention Blank (grade) 1 4 - 5 2 3 4 - 5 1 - 2 5 4 - 5 1 7 5 1 10 5 1 20 5 1 * Remarks: There was no excessive napping tendency in the present invention, but a remarkable tendency thereto in the blank. Example 2 A starting fiber web was prepared and subjected to a preliminary punching treatment by the same process as in Example 1. A weakening treatment was repeated four times on each surface of the fiber web by using the same pair of rollers as before under a nipping pressure of 20 kg/cm. Thereafter, a substantial punching treatment was carried out under the same conditions as Example 1 except for the processing speed of 4.0 m/min. The thus-obtained non-woven fabric was dyed by means of spray printing or multi-color printing, after drying, and was impregnated with polyurethane resin with a weight ratio of fabric/resin = 78/22. After calender treatment, the printed non-woven fabric of smooth surface was obtained. The resultant fabric exhibited a clear print pattern and a rich softness due to fluffs, and had a mild luster as well as a good resiliency. For a comparison of the pilling resistance, a blank was prepared by the same process as before except for the elimination of the weakening treatment. The test results were listed on Table 2. As apparent from Table 2, the non-woven fabric showed a satisfying practical performance compared to the conventional product. Especially, resistances against laundering, sweat, and sunshine were also improved to a level satisfactory for practical use due to a coating of urethane resin. Test Period (hour) Pilling Resistance Present Invention Blank (grade) 1 4 - 5 2 3 4 - 5 1 - 2 5 4 - 5 1 7 4 1 10 3 1 20 3 1 * Remarks: There was no excessive napping tendency in the present invention, but a remarkable tendency thereto in the blank. Example 3 A fiber web was prepared, provisionally punched, weakened, and substantially punched by the same process as in Example 2 except that the rough surface of the roller was prepared by coating thereon artificial diamond particles of #170. The obtained non-woven fabric was subjected to a first resin treatment of polyurethane resin coating and dip-dyed. Thereafter, a final resin treatment was carried out by using a gravure coater, whereby a weight of resin impregnated in the fabric was 18.3% relative to the total weight of the obtained fabric. Finally, the non-woven fabric was finished by an embossing machine, whereby a fine silk-like weaving pattern was imparted on the fabric surface. Similar to the preceding Examples, a blank was prepared for comparison of the pilling resistance; the test results being shown in Table 3. Test Period (hour) Pilling Resistance Present Invention Blank (grade) 1 4 - 5 2 3 4 - 5 1 - 2 5 4 - 5 1 - 2 7 3 - 4 1 10 3 1 20 3 1 * Remarks: There was no excessive napping tendency in the present invention, but a remarkable tendency thereto in the blank. Example 4 A fiber web having a weight of 65 g/m² was prepared by a filament fiber of polyethylene-terephthalate of 1.3 denier spun at a high rate by the process shown in Fig. 5A. Both surfaces of the fiber web were subjected to a first weakening treatment at a processing speed of 2.0 m/min by a pressing action of a pair of rollers, both of which had a rough surface provided by an emery cloth of #400, under a nipping pressure of 45 kg/cm along a length of the roller. Then, a first punching treatment gas carried out by a water jet-punching unit (nozzle diameter: 0.14 mm, nozzle pitch: 1.0 mm) under a water pressure of 30 kg/cm². The above weakening and punching treatments were repeated three times, in which the water pressure of the water jet punching were sequentially set at 50 kg/cm², 70 kg/cm² and 80 kg/cm² as the treatment progressed. The fabric thus obtained was subjected to a resin treatment of polyurethane resin in a dry system, and to an embossing treatment for imparting a fine silk-like weaving pattern on the fabric surface. The resultant non-woven fabric was light in weight and had an excellent warmth-keeping property different from the ordinary knit or woven fabric. For a comparison of the pilling resistance, a blank was prepared by the same process as before except for elimination of the weakening treatment. The test results are listed in Table 4. Test Period (hour) Pilling Resistance Present Invention Blank (grade) 1 4 2 - 3 3 4 - 5 2 5 4 - 5 1 - 2 7 4 - 5 1 10 5 1 20 5 1 * Remarks: There was no excessive napping tendency in the present invention, but a remarkable tendency thereto in the blank. Example 5 A starting fiber web was prepared in the same manner as Example 1. The fiber web was subjected to a preliminary punching treatment by the identical unit as utilized in Example 4, which was repeated three times while varying the water pressure to 30 kg/cm², 50 kg/cm², and 85 kg/cm² at a processing speed of 1.5 m/min. After impregnation of polyurethane resin by a wet system (the weight ratio of fabric/resin was 70/30), both surfaces of the fiber web were subjected to a weakening treatment by a pressing action of a pair of rollers, each of which had a rough surface provided by buffing of alumina ceramic, under a nipping pressure of 17 kg/cm along a length of the roller. Then, a substantial punching treatment was repeated three times by the abovesaid punching unit while varying the water pressure to 60 kg/cm², 70 kg/cm², and 80 kg/cm², respectively, whereby the membrane of the resin was broken to form a plurality of pores through the fabric. Thus, the non-woven fabric shown in Fig. 4 was obtained, which had a plurality of short fluffs on the surface and a rich softness and air-permeability. Thepilling resistance of this fabric was between the 4th and 5th grades after a 5 hour test, and 4th grade after a 10 hour test according to the I.C.I method. Example 6 A starting fiber web of 150 g/m² weight was prepared by an island-in-sea type conjugated fiber of 2.8 denier, each filament being composed of 36 island components of polyethylene-terephthalate of 0.1 denier and a sea component of polystyrene. A preliminary punching treatment was carried out by a water-jet punching unit (nozzle diameter: 0.21 mm, nozzle pitch: 1.2 mm) under a water pressure of 40 kg/cm. Then, a weakening treatment and a substantial punching treatment were repeated twice. At the first stage, the weakening treatment was done by a pair of nip rollers, one of which had a rough surface provided by an emery cloth of #80, under a nipping pressure of 80 kg/cm along a length of the roller. The substantial punching treatment was carried out in the same manner as the preliminary punching treatment except for a water pressure of 65 kg/cm². According to the first combination of the two treatments, 15% of polystyrene was removed. At the second stage, the weakening treatment was carried out under a nipping pressure of 100 kg/cm while using a rough surface roller provided with an emery cloth of #150. The substantial punching treatment was carried out under a water pressure of 85 kg/cm². According to the second stage, an amount of the remaining polystyrene was 68%, which means that a considerable part of the polystyrene component in the filament was destroyed. Thereafter, the non-woven fabric was subjected to a sea component removing treatment, in which the fabric was repeatedly impregnated with trichloroethylene followed by squeezing three times. The obtained fabric was subjected to a resin treatment and impregnated with polyurethane resin so that a weight ratio of fabric/resin was 74/26. Finally, the resultant fabric was buffed and sheared to a finished cloth state. The non-woven fabric thus obtained was remarkable, having a compact structure due to full entanglement of the filament and a very soft surface due to micro-fluffs. For the comparison of pilling resistance, a blank was prepared in the same manner as the preceding Examples. The test results are listed on Table 5. Test Period (hour) Pilling Resistance Present Invention Blank (grade) 1 4 - 5 3 - 4 3 5 3 5 5 3 7 5 3 10 5 2 - 3 20 4 - 5 2 * Remarks: There was no excessive napping tendency in the present invention, but somewhat of a tendency thereto in the blank. Example 7 A first starting fiber web of 60 g/m² was prepared from a polyamide filament of 1.0 denier, which was layered on a second fiber web of 40 g/m² formed of a cotton staple fiber. The combination fiber web was subjected to a preliminary punching treatment by a water-jet punching unit (nozzle diameter: 0.14 mm, nozzle pitch: 1 mm) under a water pressure of 30 kg/cm² and 60 kg/cm². The thus-obtained non-woven fabric was subjected to a weakening treatment twice on the filament side thereof by a pressing action of a pair of rollers, one of which had a rough surface coated with diamond particles and the other had a smooth surface made from rubber having a hardness of 80, under a nipping pressure of 30 kg/cm along a length of the roller. Then, a substantial punching treatment was carried out twice by the above punching unit under a water pressure of 65 kg/cm². A dyed product of this non-woven fabric had a favorable appearance with a natural crease on the surface of the cotton side. Further, the dyed fabric was subjected to a resin treatment of impregnation of polyurethane resin so that the weight ratio of fabric/resin was 91/9. The dyed fabrics before and after the resin treatment were estimated with regard to pilling resistance, and the test results are listed in Table 6. As apparent from the Table 6, the resin treatment is effective for improvement of the pilling resistance. Test Period (hour) Pilling Resistance (Grade) After Resin Treatment Before Resin Treatment Cotton side Filament side Cotton side Filament side 1 4 - 5 4 - 5 4 4 - 5 3 4 4 4 3 - 4 5 3 - 4 3 - 4 3 - 4* 3 10 3 - 4 3 - 4 3 - 4* 3 20 4 3 - 4 3 - 4* 3 Remarks: Marks * stand for test pieces showing a tendency to be somewhat nappy. Example 8 A starting fiber web was prepared and subjected to a preliminary punching treatment in the same manner as Example 1 except that the preliminary punching treatment was carried out on each surface of the fiber web. Then, each surface of the web was subjected to a substantial punching treatment under a water pressure of 50 kg/cm². After drying, a resin treatment was carried out, whereby polyurethane resin was impregnated in the fiber web so that the weight ratio of fabric/resin was 78/22. Thereafter, a weakening treatment was carried out by a pressing action of a pair of rollers, each of which had a rough surface provided by an emery cloth of #150, under a nipping pressure of 40 kg/cm along a length of the roller. Further a second punching treatment was processed under a water pressure of 65 kg/cm². The non-woven fabric thus obtained had a rich softness due to short fluff on the surface, and a good pilling resistance. A blank was prepared by eliminating the weakening treatment from the above process and the tests were carried out on both fabrics. The results are listed in Table 7. Pilling Resistance Air Permeability (cc/cm²/sec) Stiffness 5 hr 10 hr widthwise lengthwise (grade) (mm) Present Invention 4 - 5 4 87 51 43 Blank 2 1 13 73 65 Example 9 A starting fiber web of 65 g/m² was prepared from a filament of 1.3 denier of polyethylene-terephthalate. A preliminary punching treatment was carried out on each surface of the fiber web by a water jet punching unit (nozzle diameter: 0.14 mm, nozzle pitch: 1 mm) under a water pressure of 30 kg/cm². Then, the fiber web was subjected to a resin treatment, whereby a polyurethane resin of 18% in weight was impregnated therein. A weakening treatment was repeated three times by a pressing action of rollers, each of which had a rough surface provided by an emery cloth of #120, under a pressure of 60 kg/cm along a length of the roller. Subsequent thereto, a substantial punching treatment was carried out, whereby the final non-woven fabric was obtained. A blank was prepared by the above process except for elimination of the weakening treatment. The test results are listed in Table 8. As apparent from the Table, the non-woven fabric of the present invention was superior to the blank in pilling resistance, resiliency, and air-permeability. Pilling Resistance Air Permeability (cc/cm²/sec) Stiffness 5 hr 10 hr widthwise lengthwise (grade) (mm) Present Invention 4 3 - 4 92 47 38 Blank 1 - 2 1 28 64 53

Claims: A non-woven fabric suitable for clothing manufacture, comprising a fiber web formed substantially of continuous filament of a synthetic fiber, characterised in that a plurality of weakened portions each provided by a scratch or crack are distributed along filament regions defining at least one surface of the fiber web; some of the weakened portions being broken to form free ends, some of the free ends projecting from the fabric surface to form a nap, and some of the remaining ends being embedded in the interior of the fiber web being entangled with the filament. A non-woven fabric as defined by claim 1, wherein a resin is coated or impregnated in the fiber web. A non-woven fabric as defined by claim 2, wherein a plurality of micro-pores for air permeation are provided throughout the fabric. A non-woven fabric as defined by any preceding claim, wherein the filament is a polyamide fiber of from 0.055 dtex to 5.5 dtex (0.05 denier to 5.0 denier). A non-woven fabric as defined in any one of claims 1 to 3, wherein the filament is a polyester fiber of from 0.55 dtex to 5.5 dtex (0.05 denier to 5.0 denier). A non-woven fabric as defined by any preceding claim, wherein the filament is obtained from a composite fiber consisting of a plurality of components, which fiber is selected from an island-in-a-sea type and a splittable type fiber. A non-woven fabric as defined by any preceding claim, wherein the fiber web comprises a staple fiber as a sub-component. A non-woven fabric as defined by any preceding claim, having a pilling resistance not lower than the third grade after a 5 hour test defined by the I.C.I. method (Japanese Industrial Standard C1076, method A). A non-woven fabric as defined by any preceding claim, having a weight in a range of from 10 g/m² to 300 g/m². A non-woven fabric as defined by claim 2, wherein the resin is present in a weight range of from 1% to 80% relative to a weight of the fiber. A non-woven fabric as defined by claim 2, wherein the resin is polyurethane. A non-woven fabric as defined by any one of the preceding claims, wherein the non-woven fabric is print-dyed. A non-woven fabric as defined by any one of claims 1 to 11, wherein the non-woven fabric is dip-dyed. A method for producing a non-woven fabric suitable for clothing manufacture which method comprises collecting continuous filament of a synthetic fiber to form a fiber web, characterised in that the fiber web is subjected to a weakening treatment, in which the fiber web is nipped between a roller system or a plate system, at least one element of the system having a rough surface provided by a plurality of particles of hard material so that weakened portions are imparted to filament regions defining at least one surface of the fiber web, and a punching treatment, in which the fiber web is punched so that filament parts are entangled with each other. A method for producing a non-woven fabric as defined by claim 14, wherein the rough surface of the aforementioned roller system or plate system element has a roughness in a range of from 1 µm to 5000 µm. A method for producing a non-woven fabric as defined by claim 14 or 15, wherein the punching treatment is carried out by a water jet-punching, whereby the filament is broken at some of the weakened portions imparted by the weakening treatment and entangled with each other. A method for producing a non-woven fabric as defined by any one of claims 14 to 16, which additionally includes subjecting the fiber web to a resin treatment at any stage after the starting fiber web is prepared. A method for producing a non-woven fabric as defined by claim 17, wherein the resin treatment of the fiber web is carried out at any stage prior to the punching treatment. A method for producing a non-woven fabric suitable for clothing use, which method comprises collecting continuous filament of a synthetic fiber to form a fiber web, wherein the fiber web is subjected to the following treatments: a first punching treatment for providing a provisional entanglement between the filaments, a resin treatment for coating, or impregnation of a resin in, the fiber web characterised by a subsequent weakening treatment for imparting weakened portions on the filament constituting at least one surface of the fiber web by a nipping action of a roller system or a plate system, at least one element of the system having a rough surface provided by a plurality of particles of hard material, and a second punching treatment for breaking the filament at some of the weakened portions and providing a substantial entanglement between the filaments. A method for producing a non-woven fabric as defined by any one of claims 7, 8 and 9, wherein the resin is polyurethane.

Inventors: MORIOKA, ATSUMI, MURAKAMI, KAKUJI, NAKAYAMA, TAKASHI
Applicants: TORAY INDUSTRIES, INC.
Application year: 1986
Main classification: D04H3
IPC codes: D04H3