Abstract A process for making load limiting yarn comprising making block copolymer and then spinning the block copolymer into yarn. The process employs a twin screw extruder and
(A) forwarding aromatic polyester melt to an injection position in a twin screw extruder, (B) injecting lactone monomer into the molten aromatic polyester,
(C)dispersing the monomer into the aromatic polyester melt so that a uniform mixture forms in less than about thirty seconds, and (D)reacting the uniform mixture resulting from step © at a temperature from about 250.degree. C. to from a block copolymer. Steps (A) through (D) occur in less than
about four minutes residence time in the twin screw extruder. The process is advantageous because high IV starting aromatic polyester can be used and the short
reaction time at high temperature results in block copolymer with minimum transesterification, a high melting point, and a high melt viscosity.
Exmp. Claim 1
Ex Claim text A process comprising the steps of:
(A) forwarding aromatic polyester melt to an injection position in a twin screw extruder wherein said aromatic polyester melt has
(i) an intrinsic viscosity which is measured in a 60/40 byweight mixture of phenol and tetrachloroethane and is atleast about 0.6 deciliter/gram and
(ii) a Newtonian melt viscosity which is calculated to be at least about 7,000 poise at 280.degree. C.;
(B) injecting lactone monomer into said molten aromatic
polyester of said step (A);
(C)dispersing said injected lactone monomer into said aromatic polymer melt so that a uniform mixture forms in less than about thirty seconds; and
(D) reacting said uniform mixture from step (C) at a temperature from about 250.degree. C. to about 280.degree. C. to form a block copolymer wherein said steps (A) to (D)
occur in less than about four minutes residence time in the twin screw extruder.
Patent Number: 6613257
Issue Date: 2003 09 02
Assignee: AlliedSignal Inc.
Inventor(s): Tang, Weiming, Mares, Frank Morgan, Robert Clark
September 8, 2003