TE C HNICAL FIE L D OF INVE NTION

The present invention relates to composite yarns. More particularly, the present invention relates to a single core composite elastic yarns.

BAC KG ROUND OF THE P R E S E NT INVE NTION

A conventional single core composite elastic yarn comprises an elastic filament(s) as a single core covered with a fibrous sheath having a blend comprising synthetic fibres and natural fibres. It is known in the prior art that the single core composite elastic yarns have very very poor recovery if manufactured without synthetic yarns and provides recovery up to acceptable extent only and only when fibrous sheath comprises synthetic fibres. However, increasing the synthetic fibres percentage in the blend of fibrous sheath is not preferred as synthetic component will be in contact with user body when the single core composite elastic yarn used as weft yarns which are on back side of the fabric. Further, back staining problem is also observed in the denim fabric and garments. Moreover, the single core composite elastic yarn is not preferred for garments for which fraying treatment is done as tearing of weft yarns leads to visibility of the weft single core composite elastic yarns which gives dull look to the garment which has been rejected by the market due to staining problem. F urther, it is also observed that single core composite elastic yarn with less synthetic fibres proportion is not preferred as it has very poor recovery.

To solve the above problem, a composite dual core yarn is used which comprises one or more than one elastic filament along with one or more inelastic control filaments that act as a dual core. The dual core is covered with fibrous sheath of natural or synthetic fibres or blends of both natural and synthetic fibres. The elastic filament in the dual core comprises spandex and / or lastol filament(s), and the inelastic control filament comprises a filament formed of a polymer of copolymer of a polyamide, a polyester, and mixtures thereof. The inelastic filament(s) take care of recovery of the composite dual core yarn, whereas the elastic filamentfs) is responsible for its stretch. Both the elastic and inelastic yarns are covered with fibrous sheath of cotton fibres or a sheath blend of natural and synthetic fibres. However, the composite dual core yarn requires special set of machinery, has low tensile strength and is prone to out-centring due to more than one core. Moreover, special care is required at time of production, otherwise it results into fabric defect and degrade fabric quality. Also, time required for changing a spinning frame involved for manufacturing the known composite dual core yarn is higher and consumes more time which results in productivity loss.

Hence, there is necessity of a composite elastic yarn that can overcome at least one of the foregoing problems. S UMMARY OF THE INVE NTION

Accordingly, the present invention provides a single core composite elastic yarn consisting of an elastic filament of at least 180 deniers as a core yarn and a fibrous sheath covering the core. According to the present invention, the single core composite elastic yarn comprises at least 15% (w/w) content of the elastic filament.

According to an embodiment of the invention, the single core elastic filament is in a range between 180 denier and 300 denier. According to an embodiment of the present invention, the single core composite elastic yarn has elastic contents between 15% - 30% (w/w), and preferably between 18% - 24% (w/w). According to the present invention, the elastic filament is a polyurethane filament or polyolefin filament.

According to the present invention, the fibrous sheath is selected from a group of natural fibres including cotton, linen, cellulosic fibre, regenerated cellulosic fibre, and a combination thereof.

According to an embodiment of the present invention, the fabric woven with composite yarn contains at least 3% of elastic and maximum 8% of elastic content.

The present invention also provides a woven stretchable fabric, comprising: a plurality of warp and weft yarns having a stretch of at least 30%. The warp yarn is made from a material which is selected from a group of dyed or undyed natural fibres or man-made fibres or a blend of both and the weft yarn comprises one or more single core composite elastic yarn having a count of at least 4s Ne and the elastic filament content at least 15% (w/w), said single core composite elastic yarn made of an elastic filament of at least 180 denier as a core and a fibrous sheath covering the core.

According to an embodiment of the present invention, the woven fabric has a stretch in a range from 30% to 80% and/or a growth range between 2% and 6%.

According to another embodiment, the fabric weight of the stretchable fabric is between 5 oz. /sq. yard and 14 oz. / sq. yard.

B RIE F DE S C RIPTION OF THE DRAWINGS The above and other aspects, features, and advantages of certain exemplary embodiments of the present invention will be more apparent from the following description taken in conjunction with the accompanying drawings in which:

F ig. 1 shows cross sectional view of a single core composite elastic yarn as per an embodiment of the present invention; and F ig. 2 shows a ring spinning machine that is used to manufacture a single core composite elastic yarn which is as per an embodiment of the present invention. DE TAIL E D DE S C RIPTION OF THE INVE NTION:

While this invention is susceptible of embodiments in many different forms, there is shown in the drawings and will herein be described in detail, a preferred embodiment of the invention with the understanding that the present disclosure is to be considered as an exemplification of the principles of the invention and is not intended to limit the broad aspects of the invention to the embodiment illustrated.

The subject matter is now described with reference to the drawings, wherein like reference numerals are used to refer to like features / elements throughout. In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the claimed subject matter. It may be evident, however, that such matter can be practiced without these specific details. In other instances, well-known structures are shown in diagram form to facilitate describing the invention.

Referring F ig. 1 shows a single core composite elastic yarn (100) that comprises an elastic filament (110) of at least 180 denier as a core, and a fibrous sheath (120) covering the core (1 10). According to the present invention, the composite elastic yarn (100) has count of at least 4s Ne and the elastic filament content at least 15% (w Mi). According to an exemplary embodiment of the present invention, the composite elastic yarn has count which ranges between 4s Ne and 25s Ne. The yarn count ranges between 10s Ne and 20s Ne, in a preferred embodiment of the present invention. According to an exemplary embodiment of the present invention, the single core composite elastic yarn has elastic contents between 15% - 30% (wA/v). It shall be understood by a person skilled in the art that the range also includes 15% and 30%. According to the present invention, the elastic filament (115) as shown in

F igure 1 can be in a range from 180 denier to 300 denier. The elastic filament can be a polyurethane filament or a polyolefin filament. According to the present invention, the fibrous sheath (120) is made of natural fibres, regenerated cellulosic fibre, and a combination thereof. The natural fibres are selected from a group of cotton, linen, cellulosic fibres, protein fibres, and a combination thereof. The regenerated cellulosic fibres can be selected from a group of viscose rayon, acetate rayon, cupramonium, tencel, modal etc.

The single core composite elastic yarn as per an embodiment of the present invention can be manufactured in the ring spinning machine. The single core composite elastic yarn which is made in the ring spinning machine is also known as a core sheath yarn. Referring to the Fig. 2 shows a ring spinning machine that is used to manufacture a single core composite elastic yarn according to an embodiment of the present invention. Fig 2. shows the ring spinning machine with a fibrous sheath roving (210) that feeds as an input material in the ring spinning machine. In a preferable embodiment of the present invention, fibrous sheath roving

(210) fed is cotton. Alternatively, it can be any natural fibres including cotton, linen, cellulosic fibre, regenerated cellulosic fibre, and a combination thereof. The fibrous sheath roving (210) is passed through a drafting system (220). An elastic filament (230) is fed through a front drafting roller (240). The elastic filament (230) is covered with the fibrous sheath roving (210) after drafting and resultant a single core composite elastic yarn as per an embodiment of the present invention is wound onto a ring frame bobbin (250).

According to an embodiment of the present invention, the elastic filament (1 10, 230) ranges from 180 300 deniers and a resultant count ranges between 4s 25s Ne. According to the present invention, the elastic content in the single core composite elastic yarn may be preferably between 15% and 30% (w/w).

According to the present invention, a distance between two adjacent rollers in the ring spinning machine are increased, preferably doubled to that of an existing creel, to accommodate the elastic filament (110, 230) based on the denier of the elastic filament and/or elastic content in the single core composite yarn. As the denier of the elastic filament increases, the package size of the elastic filament also increases. S o, the distance between two adjacent rollers in the ring spinning machine is increased to accommodate the elastic filament package appropriately. For example, distance between two adjacent rollers in the ring spinning machine is 120mm for manufacturing the composite elastic yarn as per an embodiment of the present invention, as against distance between two adjacent rollers at 60mm in the prior art.

After the final single core composite elastic yarn is manufactured in the ring spinning machine, the single core composite elastic yarn is wound around the ring frame bobbin(s) (250). The composite elastic yarn is then transferred on to the winding machine for removing objectionable faults from the single core composite elastic yarn. Also, steps on the winding machine converts smaller ring bobbin into bigger length of package or predetermined length of package. The objectionable faults which are removed includes removal of thick place, thin place, Neps, etc. to provide the single core composite elastic yarn that is wound onto the final winding package. Further, in an alternative embodiment a splicing mechanism of the winding machine is implemented to splice the composite elastic yarn after removing objectionable faults. As per a present embodiment of the present invention, a woven fabric manufactured by the single core composite elastic yarn (100) is disclosed herein. The woven stretchable fabric is made of a plurality of warp yarns and a weft yarns which is woven in a textile weave that is selected from a group of plain weaves and its derivatives, twill weave, satin/sateen weave, dobby weave, etc. by known processes. The warp yarn as per an embodiment of the present invention is made from a material which is selected from a group of dyed or undyed natural fibres or man-made fibres or a blend of both. The weft yarn has the single core composite elastic yarn (100) as per an embodiment of the present invention. The warp yarn is dyed with dyes selected from a group of indigo, sulphur, reactive, pigment or a combination thereof. According to the present invention, the fabric weight is between 5 oz. / sq. yard and 14 oz. / sq. yard. The woven fabric as per an embodiment of the present invention has a stretch of at least 30%, and preferably between 30% and 80%. F urther, the woven fabric has a growth ranges between 2% and 6%, in a preferred embodiment of the present invention. The stretch and growth of the woven fabric is measured with ASTM D3107 testing method.

EXAMP L E S :

The following comparative examples are provided to demonstrate particular embodiments of the present invention. It should be appreciated by those skill in the art that the product disclosed in the examples and comparative examples that follow merely represent exemplary embodiments of the present invention. Those of skill in the art should, in light of the present disclosure, appreciate that many changes can be made in the specific embodiments described and still obtain a like or similar result without departing from the spirit and scope of the present invention.

E xample 1 :

To compare fabric parameter, a fabric with conventional dual core yarn and a fabric with invented composite elastic yarn is manufactured keeping all the fabric parameter same except weft yarn. The weaving machine used is of a rapier type. A weft yarn having a higher filament content performs well in rapier type of weaving machine, and hence the rapier type of weaving machine is preferred to manufacture the composite elastic yarn as per an embodiment of the present invention. Upon weaving, the woven composite elastic yarn undergoes a finishing process, wherein special care is taken to avoid fabric bending or curling.

P roduct number: D 163/18 (Dual Core)

Warp: 12 s Ne

Weft: 18 csy + 50D + 70D (50D Inelastic filament & 70D E lastic filament)

E PI X P PI: 68 X 54

P roduct number: D 164/18 (Invented yarn)

Warp: 12 s Ne

Weft: 18 csy +280 denier

E lastic Content in the single core elastic yarn: 24%

E PI X P PI: 68X 54

Below table: 1 shows fabric test result.

Table: 1 E xample 2,

P roduct number: D 688/1 8 (conventional yarn)

Warp: 12 s Ne

Weft: 1 8 csy + 50D + 70D (50D Inelastic filament & 70D E lastic filament) E PI X P PI: 66 X 56

P roduct number: D 687/1 8 (Invented single core elastic yarn)

Warp: 12 s Ne

Weft: 1 8 csy +210 denier

E lastic C ontent in the single core elastic yarn: 21 %

The fabric stretches, and growth is measured with testing method of AST M

D3107. Both the fabrics are having a same count and construction and same fabric manufacturing conditions, although due to changes in weft yarn the fabric results are different in weight, stretch and growth. As shown in the above table: D 163/18 product is with dual core yarn as a weft and D 164/18 product is with single core composite elastic yarn as weft. The stretch and growth of invented single core composite elastic yarn is comparable to dual core yarn.

The single core elastic composite yarn of the present invention used in the fabric and garment has a good recovery without synthetic fibres. The single core elastic yarn of the present invention provides better feeling to the users and also provides a very good look to the fraying treated garments thereof as there are no staining problems. The production cost of the single core composite elastic yarn is also effective and economical. F urther, the process of manufacturing the single core elastic composite yarn of the present invention is simple as compared with existing dual core manufacturing processes. Moreover, no deterioration takes place in yarn strength in the single core elastic composite yarn of the present invention in long term use.

Although there has been shown and described the preferred embodiment of the present invention, it will be readily apparent to those skilled in the art that modifications may be made thereto which do not exceed the scope of the appended claims. Therefore, the scope of the invention is only to be limited by the following claims: