Method for producing an elastic yarn by means of melt extrusion spinning

Abstract

The present disclosure relates to a method for manufacturing an elastic yarn by melt spinning by means of a spinning machine including an extruder and a spin pack comprising at least one die, the method comprising at least the following steps: a preliminary cold drawing of the yarn at the outlet of the die, followed by a hot drawing of the yarn then by a cold drawing of the yarn. The present disclosure also relates to a textile comprising such an elastic yarn and to a plant configured to implement this method.

1 . A method for manufacturing an elastic yarn by melt spinning by means of a spinning machine comprising an extruder, a spinning metering pump, a spin pack comprising at least one die, a cooling system, at least one take-up roll and at least one drawer roll the method comprising at least the following steps:
 A) the extruder is fed with granules of a copolymer with polyamide blocks and with polyether blocks, the polyamide blocks being selected amongst PA 11, PA 12, PA 1010, PA 1014, a copolymer thereof and a mixture thereof, the polyether blocks being blocks derived from polytetramethylene glycol, a hardness of the copolymer measured according to the standard 7619-1 being comprised between 22 and 61 ShD, in order to obtain by extrusion a molten elastomer of the copolymer with polyamide blocks and with polyether blocks,   B) the molten elastomer obtained in step A) is spun within the die of the spin pack in order to obtain a yarn of the copolymer with polyamide blocks and with polyether blocks,   C) the yarn of the copolymer with polyamide blocks and with polyether blocks obtained in step B) is subjected at an outlet of the die to cooling down to a temperature strictly lower than the glass-transition temperature of the polyamide blocks, for example to a temperature ranging from about 10° C. to about 49° C., ranging from about 10° C. to about 30° C., and ranging from about 20° C. to about 25° C.,   D) the yarn of the copolymer with polyamide blocks and with polyether blocks is subjected to a preliminary drawing at the temperature of step C),   E) the yarn of the copolymer with polyamide blocks and with polyether blocks obtained upon completion of step D) is subjected to a hot drawing at a temperature strictly higher than the glass-transition temperature of the polyamide blocks, for example at a temperature ranging from about 45° C. to about 125° C., ranging from 45° C. to 120° C., ranging from about 50° C. to about 125° C., and ranging from about 90° C. to about 120° C.,   F) the yarn of the copolymer with polyamide blocks and with polyether blocks obtained upon completion of step E) is subjected to a cold drawing at a temperature ranging from about 10° C. to about 49° C., ranging from about 10° C. to about 30° C., and ranging from about 20° C. to about 25° C.   
     
     
         2 . The method according to  claim 1 , wherein, the yarn coming out of the die of the spin pack in step B) according to a spinning metering pump linear speed VP, the yarn is drawn in step D) by passing over a take-up roll having a take-up linear speed V1, V1 being selected such that the preliminary drawing ratio D1 is greater than or equal to 2.53, where D1=V1/VP. 
     
     
         3 . The method according to  claim 1 , wherein during step E), the yarn is drawn by passing over a first drawer roll having a drawer linear speed V2, V2 being selected such that the hot drawing ratio D2 is less than or equal to 8, where D2=V2/V1. 
     
     
         4 . The method according to  claim 1 , wherein during step F), during step F), the yarn is drawn by passing over a second drawer roll having a drawer linear speed V3, V3 being selected such that the cold drawing ratio D3 is greater than or equal to 1, where D3=V3/V2. 
     
     
         5 . The method according to  claim 4 , wherein the second drawer roll is a winding roll. 
     
     
         6 . The method according to  claim 1 , wherein during step C), the yarn is cooled by water quenching. 
     
     
         7 . The method according to  claim 1 , wherein during step C), the yarn is cooled by air quenching. 
     
     
         8 . The method according to  claim 1 , wherein the yarn of the copolymer with polyamide blocks and with polyether blocks obtained upon completion of step F) is heat-set at a temperature strictly higher than the glass-transition temperature of the polyamide blocks, at a temperature ranging from about 70° C. to about 90° C., r at about 80° C. 
     
     
         9 . The method according to  claim 1 , further comprising the following step G):
 G) the yarn of the copolymer with polyamide blocks and with polyether blocks obtained upon completion of step F) is subjected to a post-drawing at a temperature strictly lower than the glass-transition temperature of the polyamide blocks, for example at a temperature ranging from about 10° C. to about 30° C., or ranging from about 20° C. to about 25° C.   
     
     
         10 . The method according to  claim 9 , wherein during step G), the yarn is post-drawn by passing over a first post-drawer roll having a linear speed V4 and then over a second post-drawer roll having a linear speed V5, V4 and V5 being selected such that the post-drawing ratio is greater than or equal to 1.65, where D4=V5/V4. 
     
     
         11 . The method according to  claim 9 , wherein the method further comprises the following step H):
 H) the yarn of the copolymer with polyamide blocks and with polyether blocks obtained upon completion of step G) is subjected to a relaxation at a temperature strictly lower than the glass-transition temperature of the polyamide blocks, for example at a temperature ranging from about 10° C. to about 30° C., or ranging from about 20° C. to about 25° C.   
     
     
         12 . The method according to  claim 11 , wherein during step H), the yarn is relaxed by passing over a winding roll having a linear speed V6 selected such that V6/V4 ranges from 1 to 1.50, from 1 to 1.25, and from 1.00 to 1.05. 
     
     
         13 . The method according to  claim 2 , wherein D1=5.07. 
     
     
         14 . The method according to  claim 3 , wherein D2=4. 
     
     
         15 . The method according to  claim 4 , wherein D3=1. 
     
     
         16 . The method according to  claim 1 , wherein the hardness of the copolymer measured according to the standard 7619-1 is comprised between 22 and 55 ShD, or between 22 and 40 ShD. 
     
     
         17 . The method according to  claim 1 , wherein the polyamide blocks are selected amongst PA 11, PA 12, a copolymer thereof and a mixture thereof. 
     
     
         18 . The method according to  claim 17 , wherein the polyamide blocks are PA 11 blocks. 
     
     
         19 . An elastic yarn obtained by the method according to  claim 1 , having a average elongation at break, measured according to the standard DIN ISO 13895, higher than or equal to at least one of the following; about 106%, about 131%, 164.5%, 180%, and about 233.3%, and/or having a springback, measured according to the standard DIN 53835-2, higher than or equal to at least one of the following: about 86.5%, 91.8%, 94%, 96.3%, and 96.6%. 
     
     
         20 . A textile comprising at least one yarn obtained according to  claim 1 . 
     
     
         21 . A garment comprising at least one yarn obtained according to  claim 1 . 
     
     
         22 . A plant configured to implement the method according to  claim 1 , the plant comprising:
 a spinning machine comprising an extruder, a spinning metering pump, a spin pack comprising at least one die,   a cooling system disposed at the outlet of the die,   at least one take-up roll disposed at the outlet of the cooling system,   at least one first drawer roll, disposed downstream of the take-up roll,   at least one second drawer roll disposed downstream of the first drawer roll,   a heating means disposed between the take-up roll and the first drawer roll.   
     
     
         23 . The plant according to  claim 22 , wherein the second drawer roll is a winding roll. 
     
     
         24 . The plant according to  claim 23 , further comprising:
 at least one first post-drawer roll disposed downstream of the winding roll,   at least one second post-drawer roll disposed downstream of the first post-drawer roll.   
     
     
         25 . A method for recycling a textile comprising at least one elastic yarn according to  claim 19 , and at least one thermoplastic yarn, preferably made of polyamide, wherein the method comprises the following steps:
 i) the textile is shredded in order to obtain particles,   ii) the particles derived from step i) are molten afterwards within an extruder in order to obtain granules of the mixture.   
     
     
         26 . The recycling-method according to  claim 25 , wherein the method it further comprises the following step iii):
 iii) a recycled yarn is spun by melt extrusion of the granules obtained in step ii).