Spinning dope and fibres spun therefrom

Details Spinning dope and fibres spun therefrom Spinning dope and fibres spun therefrom

1998-01-09

1999-09-14

Hoke, Veronica P.

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

Mixing of two or more solid polymers; mixing of solid...

525434, 264178F, 264184, C08L 7700

Patent

active

059524340

DESCRIPTION:

BRIEF SUMMARY
The invention relates to the field of making synthetic yarns, in particular to synthetic yarns spun from sulphuric acid anisotropic solutions of rigid chain aromatic polyamides blended with aliphatic polyamides.
Spinning dopes of sulphuric acid and aromatic and aliphatic polyamides, and fibres made thereof, are known from Japanese laid open No. 59163418-A, in which a spinning dope composed of 80-99 wt. % poly(p-phenylene terephthalamide) and 1-20 wt. % aliphatic polyamide is described. The fibres prepared from said dope are particularly suitable for making paper.
In EP 392558 a biphasic solution (dope) of para-aramid polymer and a polymer that can be thermally consolidated, like polyhexamethylene adipamide or poly(E-caproamide), is mentioned. The fibres made thereof are considered suitable for the preparation of thermally shaped objects (prepregs).
Although poly(p-phenylene terephthalamide) fibres are known to have very high thermal stability and very high strength, there is a need to improve their other characteristics. In the prior art, such other characteristics were enhanced by the use of blends. However, this, in its turn, was found to result in a reduction of other beneficial properties of the fibres, such as their strength and/or abrasion resistance.
It was found that by the use of a spinning dope according to the present invention, improved physical properties could be obtained without a significant loss of other beneficial properties. Such improvement was obtained by the use of a spinning dope composition comprising an aromatic and an aliphatic polyamide and concentrated sulphuric acid, and is characterized in that at least one of the aromatic and aliphatic polyamides is a copolymer built up of two aromatic and two aliphatic polymer units, respectively, the aromatic copolymer having the formula ##STR1## wherein u=75-95 wt. %, preferably 80-90 wt. % and w =5-25 wt. %, preferably 10-20 wt. %. ##STR2## wherein n=95-50 wt. %, preferably 93-60 wt. %, and m=5-50 wt. %, preferably 7-40 wt. %.
Very good results are obtained if use is made of a spinning dope according to the above invention in which about 16-19.4 wt. % of the aromatic polyamide, 0.6-4.0 wt. % of the aliphatic polyamide, and up to 100 wt % of concentrated sulphuric acid are present. Such a spinning dope can be prepared by the method described in European Patent No. 021484, which is incorporated by reference.
In order to avoid a solution of aliphatic and aromatic (co)polyamides being separated into two phases, i.e. an anisotropic and an isotropic phase, thorough agitation of the solution prior to processing is considered necessary, in particular if the polymer blend in the solution comprises more than 12 wt. % of aliphatic polyamides based on the total amount of polymer in the solution.
In Japanese patent application JP 59/116411-A it is described that adhesion to rubber and other materials, usually a finish coating is applied. By adding an aliphatic polyamide polymer to the spinning dope of poly(p-phenylene terephthalamide), an increase in adhesion is obtained. However, such an addition is attended with a significant drop in strength. By using a spinning dope of poly(p-phenylene terephthalamide), an aliphatic polymer of formula II, and sulphuric acid it is possible to make fibres or yarns which are very suitable for making reinforced and self-reinforced plastics and reinforced rubber technical articles, in particular cord for reinforcing automobile tires.
By spinning a spinning dope of sulphuric acid, poly(p-phenylene terephthalamide) and more than 5 wt. % of a common aliphatic polymer based on the total polymer amount present, fibres are obtained which show a considerable drop of (up to 28%) or even more in fibre strength as compared with the poly(p-phenylene terephthalamide) fibre strength. As is further exemplified by the test results of spinning fibre blends of poly(p-phenylene terephthalamide) and a formula II copolymer, the drop in fibre strength is much less severe. On the other hand, when using such a blend an increase in fibre adhe

REFERENCES:
patent: 5011643 (1991-04-01), Yang
patent: 5366781 (1994-11-01), Coburn et al.
Fibre Chemistry, vol. 20, No. 6, Jun. 1989 New York, US, pp. 410-412, A.V. Volokhina et al. "Preparation of Polyamide Fibres from Liquid-Crystal Solutions of Mixtures of Rigid-and Flexible-Chain Polymers".
Fibre Chemistry, vol. 19, No. 4, Mar. 1988 New York, US, pp. 270-273, M.M. Iovleva et al. "Structural Features from Mixtures of Rigid-and Flexible-Chain Polymers from Data of Electron Microscope and Sorption Methods".
Fibre Chemistry, vol. 18, No. 3, Jan. 1987 New York, US, pp. 155-161, A.V. Volokhina "Fibres from Mixtures of Rigid-Chain and Flexible-Chain Polymers".
Fibre Chemistry, vol. 16, No. 4, Mar. 1985 New York, US, pp. 266-268, A.V. Volokhina et al. "Effect Of The Chemical Structure of Introduced Polymers on the Properties of Poly-p -Phenyleneterephthalamide Solutions".
Database WPI, Section CH, Week 8433 Derwent Publications Ltd., London, GB; Class A23, AN 84-204017 & JP, A59 116 411 (ASAHI Chemical Ink KK), Jul. 5, 1984.
Database WIP Section CH, Week 8443 Derwent Publications Ltd., London, GB; Class A23, AN 84-266791 & JP,A,59 163 418 (ASAHI Chemical IND KK), Sep. 14, 1984.

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