Hyosung Corporation

Eun-lai Cho

Song-joo Choi

Jong Sung Lee

Duk-ho Oh

Chan-min Park

Chan Park

A method of producing a polyethylene terephthalate-based polyester fiber includes spinning polyethylene terephthalate based polyester to produce an undrawn yarn with an intrinsic viscosity of 0.83 or more and a density of 1338 g/cmor more, multi-stage drawing the undrawn yarn, heat-setting the drawn yarn, relaxing heat-set yarn, and winding the relaxed yarn to produce the resulting drawn yarn with an intrinsic viscosity of 0.83 or more and a density of 1.38 to 1.3865 g/cm, so that the thusly produced industrial polyester yarn with high modulus and low shrinkage contributes to significantly improving strength retention (tenacity of a dip cord/tenacity of a grey yarn) of the dip cord, produced by treating the polyester yarn with an adhesive (RFL) and subsequently heat-treating the RFL-treated polyester yarn, to be useful as a tire cord.

Process of making polyester multifilament yarn

Disclosed is a method of producing a polyethylene terephthalate-based polyester fiber, including spinning polyethylene terephthalate based polyester to produce an undrawn yarn with an intrinsic viscosity of 0.83 or more and a density of 1.338 g/cmor more, multi-stage drawing the undrawn yarn, heat-setting the drawn yarn, relaxing the heat-set yarn, and winding the relaxed yarn to produce the resulting drawn yarn with an intrinsic viscosity of 0.83 or more and a density of 1.38 to 1.3865 g/cm. Compared to a prior polyester yarn with high modulus and low shrinkage, produced according to conventional melt-spinning and drawing processes, an industrial polyester yarn with high modulus and low shrinkage according to the present invention contributes to significantly improving strength retention (tenacity of a dip cord/tenacity of a grey yarn) of the dip cord, produced by treating the polyester yarn of the present invention with an adhesive (RFL) and subsequently heat-treating the RFL-treated polyester yarn. Therefore, the polyester multifilament yarn according to the present invention is useful as a tire cord.

Polyester multifilament yarn for rubber reinforcement and method of producing the same

Process for preparing an industrial polyester multifilament yarn with high modulus and low shrinkage, in which polyethylene terephthalate polyester is wound at 2000 m/min or more to produce undrawn yarns with an intrinsic viscosity of 0.88 or higher and a density of 1.338 to 1.365 g/cm, an oiling agent is provided to undrawn yarns, the resulting undrawn yarns are wound, drawn through three stages, heat set, relaxed, and wound again. The polyethylene terephthalate polyester yarn is produced by drawing undrawn yarns at a glass transition temperature (Tg, about 80&#xb0; C.) or lower through three stages under conditions that a draw ratio of the 1st stage is greater than a draw ratio of the 2nd stage or a draw ratio of the 3rd stage and the draw ratio of the 3rd stage is greater than the draw ratio of the 2nd stage. Also, the industrial polyester yarn with high modulus and low shrinkage has an elongation 1% or more higher, and terminal modulus 10 g/d or more lower than conventional polyester high modulus low shrinkage yarns, if tenacities are identical. Treated cords formed from the polyester yarns with high modulus and low shrinkage have an excellent dimensional stability and tenacity, and so are useful as tire cords.

Process for preparing industrial polyester multifilament yarn

Described in the present invention is a polyester multifilament yarn having a high modulus and low shrinkage which provides a treated cord having high tenacity and improved dimensional stability that can be advantageously employed as a fibrous reinforcement material of rubber products such as tires and belts.

Polyester multifilament yarn

Described in the present invention is a high strength polyethylene naphthalate fiber which provides a treated cord having high tenacity and improved dimensional stability that can be advantageously employed as a fibrous reinforcement material of rubber products such as tires and belts.

High strength polyethylene naphthalate fiber

Disclosed is a process for preparing a high modulus and a low shrinkage polyester multifilament yarn of 1000 deniers or more at a spinning rate of 2,000 m/min or more, comprising the steps of: melt-extruding polyester chips having an intrinsic viscosity of 0.90 to 1.2 through a spinning nozzle and passing polyester chips through a heating zone; quenching melt-extruded yarns with the use of a radial in-to-out quenching method to solidify them; and providing spin finishes to solidified yarns before winding. The industrial polyester multifilament yarns have a coefficient of variation of 4.0% or less in a cross sectional diameter of filaments, and excellent uniformity of fineness. Treated cords formed from the industrial polyester multifilament yarns with high modulus and low shrinkage have an excellent dimensional stability and tenacity, and can be used as reinforcements of rubber goods such as tires.

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Seoul, South Korea

Eun-lai Cho