Alliedsignal Inc.

Weiming Tang

Frank Mares

Robert Clark Morgan

Monte L Nagy, Jr

Zafarur X Rahman

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 comprises (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 (C) at a temperature from about 250&deg; 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.

Process for making load limiting yarn

Load leveling yarns and webbings

The present invention provides load leveling and impact energy absorption webbing comprising warp yarn. If the webbing is used in seat belts, the webbing provides load leveling behavior from about 450 pounds (about 2,000 Newtons) to about 1,800 pounds (about 8,000 Newtons) in vehicle collision. The yarn has a force-displacement profile such that: (a) when the yarn is subjected to an initial barrier stress of from about 0.2 gram/denier to less than or equal to about 1.4 grams/denier, the yarn elongates to less than 3 percent and the initial modulus ranges from about 20 grams/denier to about 150 grams/denier; (b) upon subjecting the yarn to greater than the initial barrier stress and less than or equal to 1.8 grams/denier, the yarn elongates further to at least about 10 percent and the energy absorbed from 0 to the elongation at 1.8 grams/denier is at least about 0.0008 Joule/denier&middot;meter; and (c) upon subjecting the yarn to greater than 1.8 grams/denier, the modulus increases sharply and the yarn elongates further until the yarn breaks at a tensile strength of at least about 5 grams/denier, wherein the yarn comprises a multiplicity of fibers, all of said warp yarns having substantially the same force-displacement profile, are made from polymer having a glass transition temperature in the range from about &minus;40&deg; C. to about &plus;70&deg; C., and are not made from polybutylene terephthalate homopolymer.

The present webbing has a force-displacement profile characterized by:

Load limiting webbing

The present invention provides load leveling and impact energy absorption webbing comprising warp yarn. If the webbing is used in seat belts, the webbing provides load leveling behavior from about 450 pounds (about 2,000 Newtons) to about 1,800 pounds (about 8,000 Newtons) in vehicle collision. The yarn has a force-displacement profile such that: (a) when the yarn is subjected to an initial barrier stress of from about 0.2 gram/denier to less than or equal to about 1.4 grams/denier, the yarn elongates to less than 3 percent and the initial modulus ranges from about 20 grams/denier to about 150 grams/denier; (b) upon subjecting the yarn to greater than the initial barrier stress and less than or equal to 1.8 grams/denier, the yarn elongates further to at least about 10 percent and the energy absorbed from 0 to the elongation at 1.8 grams/denier is at least about 0.0008 Joule/denier.multidot.meter; and (c) upon subjecting the yarn to greater than 1.8 grams/denier, the modulus increases sharply and the yarn elongates further until the yarn breaks at a tensile strength of at least about 5 grams/denier, wherein the yarn comprises a multiplicity of fibers, all of said warp yarns having substantially the same force-displacement profile, are made from polymer having a glass transition temperature in the range from about -40.degree. C. to about +70.degree. C., and are not made from polybutylene terephthalate homopolymer. The web may be used for safety restraining webs for seat belts, parachute harnesses and lines, shoulder harnesses, cargo handling, safety nets, trampolines, safety belts or harnesses for workers at high attitudes, military arrestor tapes for slowing aircraft, ski tow lines, and in cordage applications such as for yacht mooring or oil derrick mooring.

The present invention provides a diblock copolymer comprising: (a) a first block of polyester wherein said first block is made from aromatic polyester having: (i) an intrinsic viscosity which is measured in a 60/40 by weight mixture of phenol and tetrachloroethane and is at least about 0.6 deciliter/gram and (ii) a Newtonian melt viscosity which is measured by capillary rheometer and is at least about 7,000 poise at 280.degree. C.; and (b) a second block of polyester wherein said second block is made from lactone monomer. The diblock copolymer is useful in engineered materials, films, and in spinning fibers for industrial applications such as seat belts. A process for making the diblock copolymer uses a twin screw extruder for melting the aromatic polyester and mixing it with monomer.

Diblock polyester copolymer and process for making

The present invention provides load leveling and impact energy absorption webbing comprising warp yarn. If the webbing is used in seat belts, the webbing provides load leveling behavior from about 450 pounds (about 2,000 Newtons) to about 1,800 pounds (about 8,000 Newtons) in vehicle collision. The yarn has a force-displacement profile such that: (a) when the yarn is subjected to an initial barrier stress of from about 0.2 gram/denier to less than or equal to about 1.4 grams/denier, the yarn elongates to less than 3 percent and the initial modulus ranges from about 20 grams/denier to about 150 grams/denier; (b) upon subjecting the yarn to greater than the initial barrier stress and less than or equal to 1.8 grams/denier, the yarn elongates further to at least about 10 percent and the energy absorbed from 0 to the elongation at 1.8 grams/denier is at least about 0.0008 Joule/denier.cndot.meter; and (c) upon subjecting the yarn to greater than 1.8 grams/denier, the modulus increases sharply and the yarn elongates further until the yarn breaks at a tensile strength of at least about 5 grams/denier, wherein the yarn comprises a multiplicity of fibers, all of said warp yarns having substantially the same force-displacement profile, are made from polymer having a glass transition temperature in the range from about -40.degree. C. to about +70.degree. C., and are not made from polybutylene terephthalate homopolymer.

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New York, NY, United States of America

Weiming Tang