Process for production of set polyacrylonitrile filaments and fibers
AssigneeHoechst Aktiengesellschaft
InventorsWalter Fester, Bernd Huber
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Abstract
The invention relates to filaments and fibers spun from at least 98% by weight of polyacrylonitrile and relative viscosities of between 2.5 and 6.0 which have tensile strengths of more than 50 cN/tex with an elongation at break of at most 15% and a shrinkage at the boil of less than 5% and to a process for their production which comprises at least 2 stretching stages with a minimum stretching ratio of 1:9 as well as a concluding setting stage in which the filaments are treated without shrinkage in dry heat at 170.degree. to 280.degree. C. Such filaments and fibers are distinguished by an increased resistance to swelling and hydrolysis and they are particularly suitable for reinforcing organic and inorganic materials.
Claims1
In a process for the production of filaments and fibers of acrylonitrile polymers, having a filament-forming substance which is composed of at least 98% by weight of acrylonitrile units, by a wet or dry spinning method, a multi-stage stretch and a setting of the resulting filaments, the improvement comprising wet-stretching a fiber-forming polymer having a relative viscosity between 2.5 and 6.0, said filaments being drawn from a jet before or after a wash, drying said filaments under tension on hot rolls, after-stretching said filaments at 140.degree. to 200.degree. C. under the action of dry heat, an after-stretch ratio being at least 1:1.5 with the total stretch ratio being at least 1:9;
- and subsequent to after-stretching, setting the filaments with shrink prevention at 170.degree. to 280.degree. C. by the action of dry heat.
Dependencies are inferred from the claim text.