FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
As amended by the Patents (Amendment) Act, 2005
&
The Patents Rules, 2003
As amended by the Patents (Amendment) Rules, 2006
COMPLETE SPECIFICATION
(See section 10 and rule 13)
TITLE OF THE INVENTION
Low tensile modulus soft feel bicomponent filaments or fibers and method of making the same
INVENTORS
Nadkarni Vikas Madhusudan, A18 Garden Estate, Off D P Road, Aundh, Pune 411007, Maharashtra, India, Huilgol Santosh Raghavendra, B-404, Devashree Gardens, R W Sawant Road, Near Rutu Park, Near Old Golden Dyes Junction, Thane (W), Maharashtra, India, Gupta Rupesh Kumar, 146,Rail Bazaar Cantt, Kanpur-208004, Uttar Pradesh, India and Kashetwar Abhijit Vasantrao, Gandhinagar, Ami, District Yavatmal - 445103, Maharashtra, India, all Indian nationals
APPLICANTS
Reliance Industries Limited, an Indian Company, Reliance Technology Centre, B-4 MIDC Industrial Area, Patalganga 410220, District Raigad, Maharashtra, India
PREAMBLE TO THE DESCRIPTION
The following specification particularly describes the nature of this invention and the manner in which it is to be performed:

FIELD OF THE INVENTION
This invention relates to low tensile modulus soft feel bicomponent filaments or fibers and method of making the same.
PRIOR ART DESCRIPTION
Sheath-core conjugated filaments or fibres of two different polymers, one forming a core and the other a sheath are known (JP 09250029A2, JP04034009A2, WO 8700561 Al, JP 57193521A2, JP2006083478A2, JP2005314864A2, JP2004065116A2, JP2004003116A2, US6136436, JP2000282342A2, JP2000234233A2, US5958548, JP11061569A2, JP10266054A2, JP10245730A2, JP10130960A2, JP09158025A2, JP09137351A2, JP09111579A2, US5512355, JP08158161A2, JP07300741A2, JP07278964A2, JP07278960A2, JP06264351A2, JP06184824A2, US5219508, JP05331748A2, JP05140848A2, JP04361615A2, JP04174720A2, JP04108114A2, JP04108113A2, JP04034017A2, US5009954, JP03172132A2, EP0434029A3, EP0434029A2, JP01266238A2, JP01118619A2, JP61132627A2, JP60126321A2 and JP56169817A2). Bicomponent filaments or fibers comprising polyester as the core and nylon among polyamides as the sheath have the advantages of both polyester and nylon. For example, polyester has advantages like easy processability and easy care properties besides increased shear modulus or tensile modulus and cost benefits. Nylon, on the other hand, has advantages like low dyeing temperatures, low modulus and high tenacity besides being dyed with brilliant acid dyes. The feel of the nylon-polyester sheath-core configuration is, however harsh because of the high tensile modulus and consequent


stiffness of the polyester backbone. The tensile modulus of nylon is about 15 to 25 gpd, whereas that of polyester is about 35 to 50 gpd. Therefore, it may not be acceptable in certain critical nylon applications like nylon sarees or nylon dress materials.
OBJECTS OF THE INVENTION
An object of the invention is to provide low tensile modulus soft feel bicomponent filaments or fibers comprising polyamide-polyester conjugated in a sheath-core configuration which has all the desirable advantages of both polyamide and polyester.
Another object of the invention is to provide a method of making low tensile modulus soft feel bicomponent filaments or fibers comprising polyamide-polyester conjugated in a sheath-core configuration which has all the desirable advantages of both polyamide and polyester.
DETAILED DESCRIPTION Of THE INVENTION
According to the invention there is provided low tensile modulus soft feel bicomponent filaments or fibers comprising polyamide and modified polyester conjugated in a sheath-core configuration.
According to the invention there is also provided a method of making low tensile
modulus soft feel bicomponent filaments or fibers, the method comprising:
i) making a polyamide melt and a modified polyester melt in separate extruders;


ii) transferring the polyamide melt and modified polyester melt into a common spin pack through separate transfer lines; and
iii) spinning the polyamide and modified polyester melts into filaments or fibers in a sheath-core configuration by pumping the polyamide and modified polyester melts through a common spinneret.
According to the invention there is also provided a process of making modified polyester by treating a polyester with a crystallization retardant. The invention further provides modified polyester obtained by the process.
Preferably, the tensile modules of the filaments or fibers is 10 to 25 gpd. Preferably the tensile modulus of the filaments or fibers is 23 gpd and lOp gpd at 5% and 10% elongation levels respectively. Preferably the polyamide is nylon 6 and the modified polyester is modified polyethylene terephthalate. Preferably, the crystallization retardant is selected from isophthalic acid, adipic acid, neopentyl glycol, methyl propylene diol or phthalic anhydride. Preferably the crystallization retardant used is 1 to 10% by weight of the polyester. Preferably, the polyamide and polyester melts are spun into filaments and further into fully drawn yarns or partially oriented yarns and subsequently texturised or drawn and wound on a take up device. Preferably, the polyamide and polyester melts are spun into staple fibres by drawing, crimping and cutting. Preferably the tensile modulus of the modified polyester is 20 to 40 gpd.


According to the invention the polyester is modified to reduce the shear modulus which governs the bending drape and feel of the polyester backbone as a result of which the filaments or fibers and the fabrics made by it in a sheath core configuration will have a low tensile modulus and a soft feel which is desirable in critical nylon applications like nylon sarees or dress materials. Besides the soft feel, bicomponent filaments or fibers of the invention will also have all the other advantages of both nylon and polyester. The modified polyester also can be used for other applications like for production of high shrinkage polyester in producing fabrics for use in apparels or dress materials, plastic bottles or containers or for production of polyester partially oriented yarns at high productivity.
The following comparative experimental example is illustrative of the invention but not limitative of the scope thereof.
Example 1
a) Nylon 6 was extruded at 274 °C through a single screw extruder and poly ethylene terephthalate (PET) modified with 2% isophthalic acid was extruded through another single screw extruder at 284°C. The polymer melts were transferred through separate transfer lines into a common spin pack. The melts in the spin pack were pumped through a common spinneret to spin fully drawn nylon-PET yarns comprising filaments in a sheath-core configuration. The tensile modulus of the resultant yarns were 23 gpd and 10 gpd at 5% and 10% elongation levels respectively. The yarns had a smooth and soft feel.


b) Nylon 6 was extruded at 274 °C through a single screw extruder and poly ethylene terephthalate (PET) was extruded through another single screw extruder at 284°C. The polymer melts were transferred through separate transfer lines into a common spin pack. The melts in the spin pack were pumped through a common spinneret to spin fully drawn nylon-PET yarns comprising filaments in a sheath-core configuration. The tensile modulus of the resultant yarns were 28 gpd and 15 gpd at 5% and 10% elongation levels respectively. The yarns had harsh and stiff feel.


We Claim :
1. Low tensile modulus soft feel bicomponent filaments or fibers comprising polyamide and modified polyester conjugated in a sheath-core configuration.
2. The bicomponent filaments or fibers as claimed in claim 1, wherein the tensile modulus of the filaments or fibers is 10 to 25 gpd.
3. The bicomponent filaments or fibers as claimed in claim 1, wherein the tensile modulus of the filaments or fibers is 23 gpd and 10 gpd at 5% and 10% elongation levels, respectively.
4. The bicomponent filaments or fibers as claimed in anyone of claims 1 to 3, wherein the polyamide is nylon 6 and the modified polyester is modified polyethylene terphthalate.
5. A method of making low tensile modulus soft feel bicomponent filaments or fibers, the method comprising:
i) making a polyamide melt and a modified polyester melt in separate extruders; ii) transferring the polyamide melt and modified polyester melt into a common spin pack through separate transfer lines; and


iii) spinning the polyamide and modified polyester melts into filaments or fibers in a sheath-core configuration by pumping the polyamide and modified polyester melts through a common spinneret.
6. The method as claimed in claim 5, wherein the modified polyester is formed by treating a polyester with a crystallization retardant.
7. The method as claimed in claim 6, wherein the crystallization retardant is selected from isophthalic acid, adipic acid, neopentyl glycol, methyl propylene diol or phthalic anhydride.
8. The method as claimed in any one of claims 5 to 7, wherein the crystallization retardant used is 1 to 10% by weight of the polyester.
9. The method as claimed in anyone of claims 5 to 8, wherein the tensile modulus of the filaments or fibers is 10 to 25 gpd.
10. The method as claimed in anyone of claims 5 to 8, wherein the tensile modulus of the filaments or fibers is 23 gpd and 10 gpd at 5% and 10% elongation levels, respectively.
11. The method as claimed in anyone of claims 5 to 10, wherein the polyamide is nylon 6 and the modified polyester is modified polyethylene terephthalate.


12. The method as claimed in anyone of claims 5 to 11, wherein the polyamide and polyester melts are spun into filaments and further into fully drawn yams or partially oriented yams and subsequently texturised or drawn and wound on a take up device.
13. The method as claimed in anyone of claims 5 to 11 wherein the polyamide and polyester melts are spun into staple fibres by drawing, crimping and cutting.
14. A process of making modified polyester by treating a polyester with a crystallization retardant.
15. The process as claimed in claim 14, wherein the crystallization retardant is selected from isophthalic acid, adipic acid, neopentyl glycol, methyl propylene diol or phthalic anhydride.
16. The process as claimed in claim 14 or 15, wherein the crystallization retardant used is 1 to 10% by weight of the polyester.
17. The process as claimed in anyone of claims 14 to 16, wherein the tensile modulus of the modified polyester is 20 to 40 gpd.
18. The process as claimed in anyone of claims 14 to 17, wherein the polyester is polyethylene terephthalate.


19. Fully drawn yams or partially oriented yams obtained by the method as claimed in claim 12.
20. Staple fibers obtained by the method as claimed in claim 13.
21. Modified polyester obtained by the process as claimed in anyone of claims 14 to 18.




ABSTRACT
Low tensile modulus soft feel bicomponent filaments or fibers comprising polyamide and modified polyester conjugated in a sheath-core configuration. Also a method of making the low tensile modulus soft feel bicomponent filaments or fibers. A polyamide melt and a modified polyester melt are made in separate extruders and transferred into a common spin pack through separate transfer lines followed by spinning the polyamide and modified polyester melts into filaments or fibers in a sheath-core configuration by pumping the polyamide and modified polyester melts through a common spinneret.