Method of making a high molecular weight polyolefin article
First Claim
1. A method to prepare a low creep, high modulus, high strength, low shrink, high molecular weight polyethylene fiber having improved strength retention at high temperatures comprisingdrawing a high molecular weight polyethylene fiber at a temperature within 10°
- C. of its melting temperature to form a drawn, highly oriented, polyethylene fiber, thenpoststretching said fiber at a drawing rate of less than about 1 second-1 at a temperature within 10°
C. of its melting temperature, andcooling said fiber under tension sufficient to retain its highly oriented state.
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Abstract
By poststretching, at a temperature between about 135° and 160° C., a polyethylene fiber, which has already been oriented by drawing at a temperature within 5° C. of its melting point, an ultra high modulus, very low creep, low shrink, high tenacity polyolefin fiber having good strength retention at high temperatures is obtained. The poststretching can be in multiple stages and/or with previous annealing. The poststretching should be done at a draw rate of less than 1 second-1. Tensile modulus values over 2,000 g/d for multifilament yarn are consistently obtained for ultrahigh molecular weight polyethylene, with tensile strength values above 30 g/d while at the same time dramatically improving creep (at 160° F. (71.1° C.) and 39,150 psi load) by values at least 25% lower than fiber which has not been poststretched. Shrinkage is improved to values less than 2.5% of the original length when heated from room temperature to 135° C. Performance at higher temperature is improved by about 15° to 25° C.
103 Citations
42 Claims
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1. A method to prepare a low creep, high modulus, high strength, low shrink, high molecular weight polyethylene fiber having improved strength retention at high temperatures comprising
drawing a high molecular weight polyethylene fiber at a temperature within 10° - C. of its melting temperature to form a drawn, highly oriented, polyethylene fiber, then
poststretching said fiber at a drawing rate of less than about 1 second-1 at a temperature within 10°
C. of its melting temperature, andcooling said fiber under tension sufficient to retain its highly oriented state. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
- C. of its melting temperature to form a drawn, highly oriented, polyethylene fiber, then
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16. A method to prepare a low creep, high modulus, low shrink high strength, high molecular weight polyolefin shaped article or fabric having improved strength retention at high temperatures, comprising
poststretching said shaped article at a drawing rate of less than about 1 second-1 at a temperature within 10° - C. of the polyolefin melting point, and
cooling said shaped article under tension sufficient to retain its highly oriented state, said shaped article prior to poststretching being fabricated from polyolefin which had been highly oriented at a higher rate than 1 second-1 and at a temperature of within about 10°
C. of its melting point. - View Dependent Claims (17, 18, 19)
- C. of the polyolefin melting point, and
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20. A method to prepare low creep, high modulus, high strength, low shrink, high molecular weight polyolefin article comprising:
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drawing high molecular weight polyolefin fiber at a temperature within 10°
C. of its melting temperature to form a drawn, highly oriented, multifilament yarn, thenpoststretching the yarn at a drawing rate of less than about 1 second-1 at a temperature within 10°
C. of its melting temperature, andcooling the yarn under tension sufficient to retain its highly oriented state. - View Dependent Claims (21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 36, 37, 38, 39, 40, 41, 42)
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31. A method to prepare low creep, high modulus, high strength, low shrink, high molecular weight polyolefin article comprising:
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(a) drawing high molecular weight polyolefin fiber at a first drawing rate and at a first temperature to form a drawn, highly oriented, multifilament yarn; (b) cooling the drawn multifilament yarn under tension sufficient to retain its highly oriented state; (c) twisting or braiding the drawn yarns, followed by (d) poststretching the twisted or braided drawn yarn at a second drawing rate and at a second temperature within 10°
C. of its melting temperature; and(e) cooling the poststretched twisted or braided yarn under tension sufficient to retain its highly oriented state. - View Dependent Claims (32, 33, 34, 35)
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Specification