Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From carboxylic acid or derivative thereof
Patent
1996-05-28
1997-12-16
Seidleck, James J.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From carboxylic acid or derivative thereof
528322, 528335, 528337, 528339, 428357, 428395, C08G 6926, C08G 7310
Patent
active
056986602
DESCRIPTION:
BRIEF SUMMARY
The invention concerns a copolyamide with an improved modulus of elasticity for melt-spinning of filaments composed of at least 75% by weight of a linear polyamide base polymer with a melting point of 150.degree.-320.degree. C., and at least 0.5 wt. % of a block comonomer. The invention also concerns filaments produced from the copolyamide, and their use.
For applications in the technical sector, polyamide fabrics are needed which, in general, must be composed of filaments with a high modulus. Fabrics of melt-spinnable filaments of linear polyamides such as polyamide 6.6 or polyamide 6, which would be available as mass produced, exhibit too low an initial modulus for many applications in the technical sector. Such fabrics are therefore preferably produced from aromatic polyamides, so called aramides. Aramide threads cannot be melt spun but must be spun from solution in a costly process. Their production is costly and limited for mass production only for economic considerations. Standard products of polyamides could be used because of their good flexibility, abrasion and adhesion properties but have the disadvantage of a low modulus of elasticity.
There has been no lack of attempts to increase the modulus of elasticity of polyamides. In the systematic study of the random modification approach, however, it was found that the incorporation of (rigid) comonomers in statistical distribution in the best case permitted only a slight increase in the E-modulus. Even the modification of polyamide 6.6 (PA 6.6) with hexahydroterephthalic acid (HHT), which is isomorphous with respect to adipic acid, yielded an improvement of only about 5% compared to standard polymer. Since below 10% co-component rigid molecules already strongly impair the stretchability, it results also in a clearly lower strength in all cases.
From EP-A-0 041 371 a process is known for the production of melt-spinnable polyamides which result in fibers with higher stiffness. Suitable poly-p-phenylene adipamide copolymers, however, can be synthesized only with great difficulty. An increase in the E-modulus is achieved in this case, only by the addition of a great excess of this comonomer due to the reaction sluggishness of the purely aromatic comonomer. In addition, in order to polymerize aromatic diamine comonomers, the reactor must be kept under vacuum during the polyamide synthesis. Therefore, in order to exclude oxygen, vacuum-tight reactors with strong agitators are required.
Another well known semi-aromatic polyamide is the homopolymer poly-m-xylylene adipamide (PMMXD.6). However, the latter is unsuitable for practical use because of its lack of stiffness in the intended field of application.
The purpose of the invention is to devise copolyamides, in which the base polymer is composed of a polyamide such as polyamide 66, polyamide 6, polyamide 6.10, polyamide 6.12; polyamide 6T, polyamide 6I, polyamide MXD.6 or polyamide 4.6, with improved mechanical properties, especially with a higher initial modulus (ATE) (modulus of elasticity), which, for instance, are suitable for production of monofilaments for screen printing fabrics or multifilaments for tire cord fabrics.
The solution to the problem lies therein that the block comonomer incorporated into the base polymer has a glass transition point (Tg) between 130.degree.-330.degree. C. and a degree of polymerization (DP) of less than 100, preferably less than 35.
It has now been found surprisingly that copolymers modified with the block comonomers according to the invention are especially well suited for production of melt-spinnable and high modulus filaments for technical fabrics. In addition, in order to achieve a high initial modulus, a significantly smaller
It has now been found surprisingly that copolymers modified with the block comonomers according to the invention are especially well suited for production of melt-spinnable and high modulus filaments for technical fabrics. In addition, in order to achieve a high initial modulus, a significantly smaller quantity of block comonomers is required
Coquard Jean
Hofer Rolf
Stahlin Roland
Hampton-Hightower P.
Rhone-Poulenc Viscosuisse SA
Seidleck James J.
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