CLIAMS:1. A yarn comprising a blend of (A) a polyester fibre having shrinkage capacity in the range of 20 to 22 % at a temperature of 130 oC and (B) a polyester fibre having shrinkage capacity in the range of 2 to 3 % at a temperature of 130 oC;
wherein, the shrinkage capacity of the yarn ranges from15 to 18 %; and
the ratio of A: B ranges from 1:2 to 1:0.5.
2. The yarn as claimed in claim 1, wherein the polyester fibres A and B are made from at least one polymer selected from the group consisting of poly(ethylene terephthalate), poly(butylene terephthalate) and poly(ethylene naphthalate).

3. The yarn as claimed in claim 1, wherein the polyester fibre/s A and/or B further comprise/s at least one co-monomer up to 2 w/w%.

4. The yarn as claimed in claim 3, wherein the comonomer is at least one compound selected from the group consisting of isophthalic acid, 2-methyl-1,3-propanediol, trimethylene glycol and cyclohexane dimethanol.

5. The yarn as claimed in claim 1, wherein the polyester fibre having shrinkage capacity in the range of 20 to 22 % is characterized by a denier size in the range from 1.2 to 4.
6. The yarn as claimed in claim 1, wherein the polyester fibre having shrinkage capacity in the range of 2 to 3 % is characterized by a denier size in the range from 1.5 to 4.
7. The yarn as claimed in claim 1, wherein the twisting capacity of the yarn ranges from 2.5 to 2.7 and turns in the range of 5 to 65 % turns per inch (tpi).

8. The yarn as claimed in claim 1, wherein the ratio of A : B is 1:1, said yarn is machine knittable

9. The fibre as claimed in claim 1, wherein the ratio of A: B ranges from 0.4:1 to 1:1, said yarn is hand knittable. ,TagSPECI:FIELD:
The present disclosure relates to a yarn suitable for knitting fabrics.
BACKGROUND:
Definition:
In the context of the present disclosure the terms “high shrinkage or high shrinkable” include a polymer having a shrinkage capacity of at least 20 %.
the terms “low shrinkage or low shrinkable” include a polymer having a shrinkage capacity below 20 %.
Bulky yarns are used in knitting to produce garments like sweaters, cardigans and the like. The desired thermal insulation or warmth in the knitted garments can only be achieved by using bulky yarns. The fibres of the yarn, the yarn thickness and the level of yarn twist are critical in achieving the desired thermal insulation. Traditionally, such garments were made of wool which was eventually replaced by acrylic fibres for economic reasons. However, the cost of the acrylic fibres has increased with increase in demand of acrylic fibres, thereby, nullifying the cost benefit of replacing wool fibre with the acrylic fibre. Therefore, there is a need for an economical viable substitute for acrylic fibres. Several polyester fibres have been suggested to replace acrylic fibres.
EP1860217 suggests a fabric prepared from two types of yarns namely a) natural or synthetic fibre, and b) polyetherester fibre made from polyetherester elastomer different in self-elongating property upon absorbing water and capable of facilitating air-permeability when wetted with water. The ratio of the first type of yarn to the second type of yarn is adjusted to 0.9 or less.
JP2000220055 suggests a woven knitted fabric consisting 3-50 wt.% fused fiber such as a sheath-core fiber having low melting co-polyester and greater than 30 wt.% highly shrinkable polyester staple fibers having 18-80% dry-heat shrinkage factor.
JP2002294534 suggests a bulky woven/knitted fabric consisting of a blend of high- shrinkage staple fibers having shrinkage factor greater than 40% and cellulosic staple fibers.
Some of the fibres suggested for making knitted fabrics contain acrylic acid at least partially, while others require the fibres to be specially treated due to which the suggested fabrics are still costly. Further, the yarn/fabric is either too bulky or cannot provide desired level of warmth.
Therefore, there is a felt need for an economic substitute for the use of acrylic acid or special raw material which is capable of providing optimum bulk which in turn is capable of providing maximum warmth.
Accordingly, the present invention provides a yarn made from polyester fibre which is economical, possesses desired shrinkage factor and is capable of providing desired warmth.
OBJECTS:
Some of the objects of the present disclosure, which at least one embodiment herein satisfies, are as follows:
An object of the present disclosure is to provide a yarn made from polyester fibres which can be knitted into fabric.
Another object of the present disclosure is to provide a yarn containing lower amounts of co-monomers.
Still another object of the present disclosure is to provide a yarn which can be easily processed to achieve a desired dye depth.
Still another object of the present disclosure is to provide a yarn which can be used to at least partially substitute acrylic fibres or wool fibres.
Yet another object of the present disclosure is to provide a process for preparing a yarn having shrinkage capacity suitable for knitting fabrics.
Other objects of the present invention will be more apparent to a person skilled in the art from the description provided herein after.
SUMMARY:
The present disclosure provides a yarn having acceptable levels of shrinkage capacity suitable for knittable applications. The yarn is prepared from two types of polyester fibres (A and B) different in shrinkage factor/capacity, blended in the ratio of 1:2 to 1:0.5.
DETAILED DESCRIPTION:
The present disclosure provides a yarn for kniting fabrics. The yarn comprises a blend of two types of polyester fibres (A and B) different in shrinkage factors/capacities. The polyester fibre A possesses shrinkage capacity in the range of 20 to 22 % when measured at a temperature of 130 oC, whereas the shrinkage capacity of the polyester fibre B ranges from 2 to 3 % at a temperature of 130 oC.
The ratio of the polyester fibres A and B can be varied to obtain a yarn having shrinkage capacity/factor ranging from 15 to 18 %. Accordingly, the ratio of polyester fibres A and B may be varied in the range of 1:2 to 1:0.5. Particularly, the ratio of the polyester fibre A to polyester fibre B is maintained at 1:1 for machine knitting, whereas for hand knitting the ratio of the polyester fibre A to polyester fibre B ranges from 0.4:1 to 1:1. Further, the yarn twist multiplier of 2.5 to 2.7 and 5 to 65 % turns per inch (tpi) for the single yarn obtained from the yarn of the present disclosure result into desired bulk after dyeing.
The shrinkage capacity/factor of the yarn is the synergistic result of the ratio of the polyester fibres A and B, the yarn twist capacity and thickness of the respective fibres.
The yarn of the present disclosure is obtained by a selection of proper single and plied yarn twist levels based on experimental data, followed by selection of suitable yarn bulking and dyeing hardware and process conditions. The advantage of the obtaining the yarn by the aforesaid process/strategy is that it does not require any alteration or addition of downstream processing hardware.
The polyester fibre having shrinkage capacity in the range of 20 to 22 % is characterized by a denier size in the range from 1.2 to 4, whereas the polyester fibre having shrinkage capacity in the range of 2 to 3% is characterized by a denier size in the range from 1.5 to 4.
The polyester fibres useful for the purpose of the present disclosure are made from at least one polymer selected from the group consisting of poly(ethylene terephthalate), poly(butylene terephthalate) and poly(ethylene naphthalate).
The polyester fibre/s A or B or both may comprise at least one co-monomer selected from the group consisting of isophthalic acid, 2-methyl-1,3-propanediol, trimethylene glycol and cyclohexane dimethanol. The amount of co-monomer in the polyester fibre having shrinkage capacity in the range of 20 to 22 %, ranges up to 2 w/w%.
The present disclosure is further described in the light of the following examples which are set forth for illustration purpose only and not to be construed for limiting the scope of the disclosure.
Examples:
Example 1: Preparation of high shrinkage knitted fabric
High shrinkable fiber having shrinkage 20% and normal shrinkable fiber having shrinkage 3% were blended in the proportion of 4:5 to obtain a yarn. Yarn twisting per inch was 2.6. In next step, bulking and dyeing of the yarn in hank form was carried in a high temperature high pressure cabinet dyeing machine at dyeing temperature of 130 oC and holding time of 30 mins. The final yarn obtained after this step possesses shrinkage capacity of 17%.
Example 2: Preparation of high shrinkage knitted fabric
High shrinkable fiber having shrinkage 21% and normal shrinkable fiber having shrinkage 3% were blended in the proportion of 3:7 by hand knitting to obtain a yarn. Yarn twisting per inch was 2.7. In next step, bulking and dyeing of the yarn in hank form was carried in a high temperature high pressure cabinet dyeing machine at dyeing temperature of 130 oC and holding time of 30 mins. The final yarn obtained after this step possesses shrinkage capacity of 18%.
Throughout this specification the word “comprise”, or variations such as “comprises” or “comprising”, will be understood to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps.
The use of the expression “at least” or “at least one” suggests the use of one or more elements or ingredients or quantities, as the use may be in the embodiment of the disclosure to achieve one or more of the desired objects or results.
Any discussion of documents, acts, materials, devices, articles or the like that has been included in this specification is solely for the purpose of providing a context for the disclosure. It is not to be taken as an admission that any or all of these matters form a part of the prior art base or were common general knowledge in the field relevant to the disclosure as it existed anywhere before the priority date of this application.
The numerical values mentioned for the various physical parameters, dimensions or quantities are only approximations and it is envisaged that the values higher/lower than the numerical values assigned to the parameters, dimensions or quantities fall within the scope of the disclosure, unless there is a statement in the specification specific to the contrary.
While considerable emphasis has been placed herein on the particular features of this disclosure, it will be appreciated that various modifications can be made, and that many changes can be made in the preferred embodiments without departing from the principles of the disclosure. These and other modifications in the nature of the disclosure or the preferred embodiments will be apparent to those skilled in the art from the disclosure herein, whereby it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the disclosure and not as a limitation.
The foregoing description of the specific embodiments will so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the embodiments as described herein.