Method for producing hollow rayon fibers

Details Method for producing hollow rayon fibers Method for producing hollow rayon fibers

2002-01-04

2003-06-24

Edwards, N. (Department: 1774)

Plastic and nonmetallic article shaping or treating: processes

Forming continuous or indefinite length work

Shaping by extrusion

C428S393000, C428S398000

Reexamination Certificate

active

06582644

ABSTRACT:

TECHNICAL FIELD
The present invention relates to a novel method for producing hollow rayon fibers, which are light and heat-insulating, in a simple and environmentally friendly manner.
PRIOR ART
Rayon fibers, which are artificial fibers with the same chemical structure as cellulose, are defined as regenerated cellulose fibers, in which 15% or fewer hydroxyl groups are substituted (Fibers Chemistry, Manachem Lewin Eli M. Pearce, Dekker p.914, 1985), and usually used in high-grade applications with favorable intrinsic brightness, specific gravity, and sense of touch.
Viscose rayon (hereafter, referred to simply as ‘rayon’) can be produced by spinning a sodium cellulose xanthate solution, prepared by adding a sodium hydroxide solution and CS
2
to cellulose, into an aqueous solution of sulfuric acid and zinc sulfate. Such method was commercialized, but recent legislation, in response to environmental concerns stemming from air pollution, has been enacted to make the method useless because it produces harmful substances such as CS
2
.
DISCLOSURE OF THE INVENTION
Therefore, it is an object of the present invention to provide a commercial method for producing hollow rayon fibers, which are light and heat-insulating, in a simple and safe manner.
To accomplish the above object, the present invention provides a method for producing hollow rayon fibers, which comprises the steps of saponifying cellulose acetate fibers with a degree of acetyl substitution of 2.0 to 3.0 (acetification of 45 to 62.5%) by use of an aqueous solution of strong and weak alkali in such a way as to substitute 27 to 75% of the total acetyl groups of cellulose acetate fibers with hydroxyl groups in order to form a cellulose layer with a mixed crystalline structure of cellulose II and TV; followed by dissolving a cellulose acetate portion which is not saponified by use of an organic solvent.


REFERENCES:
patent: 4086418 (1978-04-01), Turbak et al.
patent: 4130689 (1978-12-01), Costa
patent: 4242411 (1980-12-01), Costa
patent: WO02/057521 (2002-07-01), None

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