FIELD OF THE INVENTION

The present invention relates to core spun elastic composite yarn having a fibrous sheath covering an elastic performance filament and a staple spun yarn. In particular, the present core spun yarn is woven into fabrics exhibiting excellent stretch, recovery, hand feel characteristics and improved yarn piecing properties.

BACKGROUND

Conventional stretch fabric is commonly made up of core spun spandex yarn. Warping and/or filling of the conventional core spun spandex yarn result in fabric of high shrinkage and stretchability which requires additional finishing process, such as heat setting. Generally, the conventional stretch fabric is associated with drawbacks, such as limited elongation and growth, and stability of the fabric width are being affected.

Elastic bi-component polyester filament has been disclosed in US Pat. No. 3,671,379 and woven stretch fabrics comprising this bi-component polyester filament is disclosed in US Pat. No. 5,922,433, US Pat. No.7,143,790 and US Pat. No, 7,299,828. However, these fabrics woven from bare bi-component polyester filament have a strong synthetic feel and look. Such fabrics are therefore limited to be used in filling and denim. Moreover, piece dyeing these woven stretch fabrics of bi-component polyester filament must be performed in two separate dyeing processes and elongation of the fabric is inevitably affected.

US Pat. No. 7,310,932 discloses fabric made up of core spun yarn comprising bi-component polyester filament covered with staple fibers. Although the fabric disclosed in the '932 patent is associated with improved appearance and hand-feel, grinning effect and limited elongation of the fabric remain.

US Pat. No. US 7,299,828 B2 and US 8,093,160 disclose fabric made up of core spun yarn containing at least one elastic performance filament and at least one inelastic or elastic filament. Woven fabric made of such yarns can have a good elongation and recovery, but the existing problem of grinning effect, low piecing strength and synthetic texture remain unsolved. As a result, there is a need to develop a new core spun composite yarn that produces fabrics with desirable stretchability, good recovery, hand feel, reduced grinning and improved piecing characteristics.

SUMMARY OF THE INVENTION

The objective of the present invention is to provide a new core spun elastic composite yarn having excellent elongation, excellent recovery, and better hand feel properties, and solve the problem of grinning effect and low yarn piecing strength at the piecing position as compared to existing composite yarns. The present composite yarn is suitable for denim, piece dyed fabric, warp and filling. The present invention is a core spun elastic composite yarn comprises at least one elastic performance filament, and at least one staple spun yarn. In one embodiment, said elastic performance filament ranges from about 20 denier to about 140 denier. In another embodiment, said staple spun yarn to have an English cotton yarn count (Ne) ranging from about 8 to about 100, preferably from about 20 to 60.

In another embodiment, the present invention further comprises a fibrous sheath which forms a composite yarn with said at least one elastic performance filament and at least one staple spun yarn. Said fibrous sheath may be staple fibers such as cotton, polyester, nylon, rayon, wool, acrylic and a combination thereof. In general, there is no restriction on the type of staple fibers that can be used in the present invention as long as the properties of the present invention are unaffected. In yet another embodiment, the fibrous sheath ranges from English cotton yarn count from about Ne 4 to Ne 60. In yet another embodiment, the fibrous sheath ranges from Ne 7 to Ne 40.

Another objective of the present invention is to provide a textile fabric woven from the core spun elastic composite yarn of the present invention. In particular embodiment, the textile fabric is a denim fabric.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side view of a process and apparatus for manufacturing the core spun elastic composite yarn in accordance with one embodiment of the present invention.

FIG. 2 is a front view of a process and apparatus for manufacturing the core spun elastic composite yarn in accordance with one embodiment of the present invention. FIG. 3 is a side view of a process and apparatus for manufacturing the core spun elastic composite yarn in accordance with another embodiment of the present invention.

FIG. 4 is a front view of a process and apparatus for manufacturing the core spun elastic composite yarn in accordance with another embodiment of the present invention.

FIG. 5 is a side view of a process and apparatus for manufacturing the core spun elastic composite yarn in accordance with a third embodiment of the present invention.

FIG. 6 is a side view of a process and apparatus for manufacturing the core spun elastic composite yarn in accordance with a third embodiment of the present invention.

FIGs. 7 show piecing position of elastic yarn with one elastic performance filament and one inelastic polyester filament (FIG. 7a), and piecing position of elastic yarn with one elastic performance filament and one staple spun yarn (FIG. 7b).

FIG. 8 is a table showing the physical properties of textile fabrics woven from three exemplary embodiments of the present invention.

DEFINITIONS

"Warp" means the lengthwise threads in a woven fabric.

"Filling" or "weft" means threads widthways in a fabric as woven.

"Spandex" means a manufactured fiber with good elasticity in which the fiber-forming substance is a long-chain synthetic polymer comprised of at least 85% of segmented polyurethane.

"Filament" means a fibrous of indefinite length.

"Fiber" means a fibrous strand of definite length, such as staple fiber. "Yarn" means a product of substantial length and relatively small cross-section consisting of fibers and/or filament(s) with or without twist.

"Sliver" means an assemblage of fibers in continuous form without twist.

"Roving" is a name given, individually or collectively, to the relatively fine fibrous strands used in the later or final processes of preparation for spinning.

"Spinning" means the drafting and where appropriate the insertion of twist in natural or staple man-made fibers to form a yarn.

"Core Yarn" means a yarn consisting of a number of component yarns, of which one or more are constrained to lie permanently at the central axis of the composite thread, whilst the remaining yarns act as covering yarns.

"Spun yarn" means a yarn that consists of staple fibers held together usually by twist.

"Core spun yarn" means a yarn consisting of a yarn surrounded by staples fibers. The yarn has the strength and/or elongation of the central thread whilst exhibiting most of the other characteristics of the surface staple fibers.

"Draft ratio" or "Draft" is the ratio between length of a stock filamentary strand from a package thereof which is fed into a spinning machine to the length of the filamentary strand delivered from the spinning machine. A draft ratio of greater than 1.0 is thus a measure of the reduction in bulk and weight of the stock filamentary strand.

"Elastic recovery" means the immediate change in elongation experienced by a textile during a loading cycle when, after being held at a defined elongation for a defined time, the applied tension is removed.

Definitions of the above terms and any other technical terms used herein are as readily would understand by one skilled in the art in the field of textile and as defined in the Textile Terms and Definitions (9 Edition) by The Textile Institute, UK, disclosures thereof are incorporated herein by reference in its entirety.

DETAILED DESCRIPTION OF THE INVENTION

Reference is made in detail to the presently preferred embodiment of the present invention, which serve to explain the principles of the invention. The embodiments or examples disclosed herein are described in sufficient detail to enable those skilled in the art to practice the invention, and it is to be understood that other embodiments may be utilized, and that changes may be made without departing from the spirit of the present invention.

The present core spun elastic composite yarn comprises at least one elastic performance filament, at least one staple spun yarn and a fibrous sheath comprised of a mass of staple fibers. Said fibrous sheath may surround the at least one elastic performance filament and the at least one staple spun yarn independently. In another embodiment, the at least one elastic performance filament and the at least one staple spun yarn are first twisted together to form a central thread and the fibrous sheath surrounds said central thread.

Any commercially available elastic performance filament may be employed in the present composite yarn. In one embodiment, the elastic performance filament is made from spandex or lastol polymers. Other elastic performance filament includes, but is not limited to, ethylene/ -olefm interpolymers. U.S. Pat. Nos. 5,272,236, 5,278,272, 5,322,728, 5,380,810, 5,472,775, 5,645,542, 6,140,442 and 6,225,243 disclose various examples of elastic performance filament applicable for the present invention, disclosures thereof are incorporated herein by reference in their entirety. The elastic performance filament of the present invention typically has 40 to 140 denier and 1% to 40% of total weight of the composite yarn. In another embodiment, the draft of the elastic performance filament is typically ranges from 1.5 to 5.0.

The staple spun yarn of the present composite yarn may be made of any material known to those skilled in the art. Examples of staple spun yarn suitable for the present invention includes, but are not limited to, natural, re-generated, synthetic, dyed, non-dyed fibers. The present staple spun yarn may be s-twist or z-twist. In one embodiment, the staple spun yarn has an English cotton count ranges Ne 8 to Ne 100. In another embodiment, the English cotton count is Ne 20 to Ne 60. In another embodiment, the present staple spun yarn is about 4% to 50% of the total weight of the present composite yarn. In yet another embodiment, the draft of the staple spun yarn is 1.0 to 1.3.

The fibrous sheath is formed from a relatively dense mass of randomly oriented entangled spun synthetic staple fibers (e.g., polyamides, polyesters and the like) or spun natural staple fibers Other examples includes, but is not limited to, cotton, viscose rayon, polyester, wool, acrylic or a combination thereof. Particularly, the fibrous sheath may be ring-spun from a roving of staple fibers and forms an incoherent mass of entangled spun staple fibers. Length of the staple fiber is not critical. In yet another embodiment, the fibrous sheath ranges from English cotton yarn count from about Ne 4 to Ne 60. In yet another embodiment, the fibrous sheath ranges from Ne 7 to Ne 40.

The present core spun elastic composite yarn may be used as a warp and/ or filling yarn to form woven fabrics exhibiting excellent recovery characteristics. The present composite yarn has a yarn count ranges Ne 4 to Ne 60, preferably Ne 7 to Ne 40. In one embodiment, the fabric woven from the present composite yarn is a plain weave, twill weave and/ or satin weave pattern. Such fabrics in accordance with the present invention have at least about 20% stretch or greater. More specifically, fabrics in accordance with the present invention exhibits improved less synthetic hand-feel, improved hairiness, resistant to abrasion as compared to existing composite yarns, such as those having a filament core/ central thread of an elastic filament combining with an inelastic/ elastic filament. Fabrics of the present invention also have reduced or no grinning effect and high piecing strength, thereby efficiency of the weaving process is improved. When the present composite yarn is made of 100% cotton or rayon/cotton blend, the common white spot problem occurs in denim fabric is eliminated when the composite yarn is used as warp. Furthermore, 100% cotton or rayon/cotton blend of the present composite yarn also avoid two dyeing process for piece dyed fabrics.

The present composite yarn may be manufactured by any staple fiber spinning process, such as core spinning, ring spinning and the like as readily known by those skilled in the art. Process and apparatus for making the present elastic core spun composite yarn is shown in FIGs. 1 and 2. During the spinning process, the elastic performance filament 21 and staple spun yarn 22 are unwound from the tube 34 & 35 respectively in the direction of 41 & 42 at different speed according to the desired draft. The draft of elastic performance filament is calculated by the ratio of the surface speed of front roller 31 and the tube 34, whereas the draft of staple spun yarn is calculated by the ratio of the surface speed of front roller 31 and the tube 35. In one embodiment of the present invention, the elastic performance filament has a draft which is at least twice or three times the draft of the staple spun yarn.

The staple fibers or roving 13 and 14 are unwound from tube 11 and 12 to meet the elastic performance filament 21 and staple spun yarn 22 at the front roller 31. The position of the elastic performance filament on the roving 13 is adjusted by roller 36 and guide 38 whereas the position of staple spun yarn 22 on the roving 14 is adjusted by roller 37 and guide 39. As depicted in FIG. 2, elastic performance filament 21 and staple spun yarn 22 are individually twisted with staple fibers or roving 13 and 14 first, and thereafter twisting together at the front roller 31 forming the present core spun elastic composite yarn. The alignment of the elastic performance filament 21 and staple spun yarn 22 on the roving can effectively reduce the grinning effect. The present core staple spun yarn has reduced grinning effect and improved the piecing strength at the piecing position.

Another embodiment of process and core spinning apparatus to make the present composite yarn is shown in FIGs. 3 and 4. The elastic performance filament 21 and that staple spun yarn 22 are unwound from the tubes 34 and 35 respectively in the directions of 41 and 42 at different speed according to the desired draft. Filament 21 and yarn 22 are twisted together by roller 36 first forming a filament strand/ central thread, thereafter staple fibers or roving of 13 and 14 are twisted around the filament strand to form core spun yarn l.The position of the elastic performance filament 21 and staple spun yarn 22 on the staple fibers or roving 13 and 14 is adjusted by roller 36 and guides 38 and 39.

Another embodiment of the core spinning apparatus is shown in FIGs. 5 and 6, wherein the elastic performance filament is twisted with the staple spun yarn to form a central strand 23 beforehand. The apparatus that is useful in twisting the elastic performance filament with the staple spun yarn includes, but is not limited to, ring spinning machine, open end spinning machine and vortex spinning machine. The filamentary strand is unwound from the tube 34 in the direction 41. The draft of central strand is calculated by the ratio of the surface speed of front roller 31 and the tube 34. The staple fibers or roving 13 and 14 are unwound from the tubes 11 and 12 to meet central strand 23 at the front roller 31. The position of the core staple spun yarn on the roving 13 and 14 is adjusted by roller 36 and guides 38 and 39. The grinning effect of the conventional elastic core yarn which comprises an elastic performance filament and inelastic or elastic filament at the piecing position is shown in FIG. 7a. The present invention of elastic core spun composite yarn comprises elastic performance filament and staple spun yarn as the filament core has no grinning effect at the piecing position (FIG. 7b), The present elastic core spun composite yarn can be used to provide a woven stretch fabric designed as a filling stretch, warp stretch or bi-stretched by using the elastic core spun composite yarn in a warp, weft or filling and warp directions respectively. Stretch fabric woven from the present composite yarn may have the fabric weight ranging from 4 oz/square.yard to 16 oz/square.yard (oz/sq.yd).

The following are textile fabric woven from exemplary embodiments of the present invention and the associated properties (FIG. 8).

Example 1: Denim Weft Stretch Fabric

A denim stretch fabric having a weft yarn Ne 16 in accordance with the present invention. The weft yarn includes cotton fibrous sheath and a core polyester staple spun yarn Ne 45 and spandex of 40 denier. The denim stretch fabric exhibits good elongation (27.4%) and growth (3.0%).

Example 2: Denim Weft Stretch Fabric

The weft yarn of Ne 16 in accordance with the present invention comprises a core strand of 100% cotton spun yarn Ne 45 and spandex of 40 denier covered by 100% cotton fibrous sheath. The fabric has good elongation (34.6%) and growth (5.4%). The fabric exhibits 100% cotton feel and no grinning effect in the fabric and at the piecing position. The present core strand of Example 2 is also useful as warp.

Example 3: Denim Weft Stretch Fabric

The weft with 100% cotton fibrous sheath and a core polyester staple spun yarn Ne 60 and spandex of 40 denier. Good elongation (30.1%) and growth (3.6%) are exhibited in the fabric woven therefrom.

Without further elaboration, it is believed that one skilled in the art can, based on the description herein, modify the present invention without departing the spirit of the present invention and utilize the present invention to its fullest extent as set forth in the appended claims, publications recited herein are hereby incorporated by reference in their entirety.