High Molecular Weight Polyamides and CoPolyamides with Uniform RV and Low Gel Content

Abstract

A customizable polyamide polymer, in particular Nylon 66, Nylon 6, and copolyamides, having a high molecular weight, excellent color, and low gel content is disclosed. In particular, disclosed is a polymer having a relative viscosity greater than 50 as measured in a 90% strength formic acid solution; consistent viscosity with a standard deviation of less than 1; a gel content no greater than 50 ppm as measured by insolubles larger than 10 micron; an optical defect content of less than 2,000 parts per million (ppm) as measured by optical control system (OCS). The polymer can be made into monofilaments or a multifilament yarn. Also disclosed is a process of producing the polymer using in-line vacuum finishing technology in the absence of steam or other gases in the second, or post condensation, step of the polymer process.

1 . A high molecular weight polyamide polymer, wherein the polyamide polymer is characterized by a precision Relative Viscosity greater than 50 as measured in a 90% strength formic acid solution, wherein the precision Relative Viscosity has an RV Standard Deviation of less than or equal to 1.25. 
     
     
         2 . The polyamide polymer of  claim 1 , wherein the polymer is Nylon 6,6 polymer. 
     
     
         3 . The polyamide polymer of  claim 1 , wherein the polymer is Nylon 6 polymer. 
     
     
         4 . The polyamide polymer of  claim 1 , wherein the polymer is a random copolymer of Nylon 6,6 and Nylon 6 
     
     
         5 . The polyamide polymer of  claim 1 , wherein the Relative Viscosity is greater than 70 as measured in a 90% strength formic acid solution. 
     
     
         6 . (canceled) 
     
     
         7 . The polyamide polymer of  claim 1 , wherein the Relative Viscosity is in the range of from 50 to 200 as measured in a 90% strength formic acid solution. 
     
     
         8 . The polyamide polymer of  claim 1 , wherein the Relative Viscosity is in the range of from 75 to 100 as measured in a 90% strength formic acid solution. 
     
     
         9 . (canceled) 
     
     
         10 . The polyamide polymer of  claim 1 , wherein the precision Relative Viscosity has an RV Standard Deviation of less than 1.0. 
     
     
         11 - 15 . (canceled) 
     
     
         16 . The polyamide polymer of  claim 1 , wherein the polyamide polymer is characterized by:
 a Gel Content Parameter of less than 50 ppm as determined by parts per million insolubles larger than 10 microns in 90% formic acid at 25° C.; and   an Average Optical Defect Level of less than 2,000 parts per million (ppm) as measured by optical scanning of pellets.   
     
     
         17 . The polyamide polymer of  claim 16 , wherein the polymer is Nylon 6,6 polymer. 
     
     
         18 . The polyamide polymer of  claim 17 , wherein further the Nylon 6,6 polymer exhibits a Gel Content Parameter of less than 40 ppm as determined by parts per million insoluble larger than 10 microns in 90% formic acid at 25° C. 
     
     
         19 - 25 . (canceled) 
     
     
         26 . A method of making a high molecular weight polyamide polymer with a precision Relative Viscosity and low gel content comprising:
 (a) providing a first polyamide polymer melt comprising a first polyamide polymer with a first Relative Viscosity;   (b) feeding the first polyamide polymer melt to a twin screw extruder;   (c) melt-processing the first polyamide polymer melt under vacuum in the twin screw extruder in the absence of added steam to remove steam and other volatiles therefrom, thereby increasing the molecular weight of the polymer melt to provide a second polyamide polymer melt comprising a second polyamide polymer with a second Relative Viscosity,
 said second polyamide polymer being characterized by either: (i) a precision Relative Viscosity greater than 50 as measured in a 90% strength formic acid solution with an RV Standard Deviation of less than or equal to 1.25; or (ii) a Gel Content Parameter of less than 50 ppm as determined by parts per million insoluble larger than 10 microns in a 90% formic acid solution at 25° C.; 
   (d) optionally feeding the second polymer melt to a residence time dwell vessel and melt-processing the second polymer melt in the residence time dwell vessel to provide a third polyamide polymer melt comprising a third polyamide polymer with a third Relative Viscosity higher than the second Relative Viscosity of the second polyamide polymer,
 said third polyamide polymer being characterized by either: (i) a precision Relative Viscosity greater than 50 as measured in a 90% strength formic acid solution with an RV Standard Deviation of less than or equal to 1.25; or (ii) a Gel Content Parameter of less than 50 ppm as determined by parts per million insoluble larger than 10 microns in a 90% formic acid solution at 25° C. and an Average Optical Defect level of less than 2000 ppm as measured by optical scanning at 50 micron resolution; and 
   (e) recovering a product polyamide polymer characterized by either: (i) a precision Relative Viscosity greater than 50 as measured in a 90% strength formic acid solution with an RV Standard Deviation of less than or equal to 1.25; or (ii) a Gel Content Parameter of less than 50 ppm as determined by parts per million insoluble larger than 10 microns in a 90% formic acid solution at 25° C. and an Average Optical Defect level of less than 2000 ppm as measured by optical scanning at 50 micron resolution.   
     
     
         27 . The method of making a high molecular weight polyamide polymer with a precision Relative Viscosity and a low gel content according to  claim 26 , wherein the polyamide polymer melt is melt-processed in the twin screw extruder at a temperature in the range of from 280° C. to 350° C. 
     
     
         28 . (canceled) 
     
     
         29 . The method of making a high molecular weight polyamide polymer with a precision Relative Viscosity and a low gel content according to  claim 26 , wherein the polyamide polymer melt is melt-processed in the twin screw extruder under vacuum in the range of 600 mm Hg vacuum to 725 mm Hg vacuum. 
     
     
         30 . (canceled) 
     
     
         31 . The method of making a high molecular weight polyamide polymer with a precision Relative Viscosity and a low gel content according to  claim 26 , wherein the polyamide polymer melt is melt-processed in the twin screw extruder for a residence time in the extruder of less than 60 seconds. 
     
     
         32 . (canceled) 
     
     
         33 . The method of making a high molecular weight polyamide polymer with a precision Relative Viscosity and a low gel content according to  claim 26 , wherein the polyamide polymer melt is melt-processed in the twin screw extruder for a residence time in the extruder of less than 20 seconds. 
     
     
         34 . The method of making a high molecular weight polyamide polymer with a precision Relative Viscosity and a low gel content according to  claim 26 , wherein the polyamide polymer melt is melt-processed in the twin screw extruder for a residence time in the extruder of from 10 seconds to 60 seconds. 
     
     
         35 . The method of making a high molecular weight polyamide polymer with a precision Relative Viscosity and a low gel content according to  claim 26 , comprising feeding the second polymer melt to a residence time dwell vessel and melt-processing the second polymer melt in the residence time dwell vessel to provide the third polyamide polymer melt comprising a third polyamide polymer with a third Relative Viscosity higher than the second Relative Viscosity of the second polyamide polymer, said third polyamide polymer being characterized by either: (i) a precision Relative Viscosity greater than 50 as measured in a 90% strength formic acid solution with an RV Standard Deviation of less than or equal to 1.25; or (ii) a Gel Content Parameter of less than 50 ppm as determined by parts per million insoluble larger than 10 microns in a 90% formic acid solution at 25° C. and an Average Optical Defect level of less than 2000 ppm as measured by optical scanning at 50 micron resolution. 
     
     
         36 . The method of making a high molecular weight polyamide polymer with a precision Relative Viscosity and a low gel content according to  claim 35 , wherein the polyamide polymer melt is melt-processed in the residence time dwell vessel at a temperature in the range of from 280° C. to 350° C. 
     
     
         37 - 38 . (canceled) 
     
     
         39 . The method of making a high molecular weight polyamide polymer with a precision Relative Viscosity and a low gel content according to  claim 35 , wherein the polyamide polymer melt is melt-processed in the residence time dwell vessel for a residence time in the residence time dwell vessel of at least 1 minute. 
     
     
         40 . (canceled)