Bleaching and dyeing; fluid treatment and chemical modification – Chemical modification of textiles or fibers or products thereof – Cellulose fibers
Patent
1983-10-28
1986-04-22
Czaja, Donald
Bleaching and dyeing; fluid treatment and chemical modification
Chemical modification of textiles or fibers or products thereof
Cellulose fibers
264187, 264189, 264195, 264232, 264344, 536 30, D06M 102, D01F 200, C08B 1506
Patent
active
045839840
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention concerns a procedure for treating cellulose derivative fibres. More specifically, the invention concerns a procedure for regulating the properties of cellulose carbamate fibres. Furthermore, the invention concerns a novel procedure for manufacturing regenerated cellulose fibres.
In the Finnish patent application No. 61,033 and U.S. Pat. No. 4,404,369 is disclosed a procedure for manufacturing an alkali-soluble cellulose derivative from cellulose and urea at elevated temperature. The procedure is based on the fact that on heating urea to its melting point or to a higher temperature it begins to decompose into isocyanic acid and ammonia. Isocyanic acid in itself is not a particularly stable compound; it tends to trimerize into isocyanuric acid. Furthermore, isocyanic acid also tends to react with urea, whereby biuret is formed. Isocyanic acid also reacts with cellulose, producing an alkali-soluble cellulose derivative which is called cellulose carbamate. The reaction may be written as follows: ##STR1## The cellulose compound thus produced, cellulose carbamate, may be dried subsequent to washing and stored even over prolonged periods, or it may be dissolved in an aqueous alkali solution for manufacturing fibres, for instance. From this solution can be manufactured cellulose carbamate fibres or films by spinning or by extruding, in like manner as in the viscose manufacturing process. The keeping quality of cellulose carbamate and its transportability in dry state afford a great advantage compared with cellulose xanthate in the viscose process, which cannot be stored nor transported, not even in solution form.
If, for instance, continuous fibre or filament manufactured from cellulose carbamate appropriate for textile uses is desired, the carbamate is first dissolved in alkali, e.g. in aqueous sodium hydroxide solution. From this solution may then be precipitated fibre or film, for instance in like manner as in the manufacturing of viscose fibre cellulose is regenerated from the NaOH solution of cellulose xanthate. In this connection, the cellulose carbamate solution is spun through spinnerets into an acid precipitation bath, which causes precipitation of the cellulose carbamate. The precipitation may also be accomplished into lower alcohols such as methanol, ethanol or butanol, or into hot aqueous salt solutions.
SUMMARY OF THE INVENTION
The properties of precipitated fibres are substantially influenced by the nitrogen content of the fibre, that is, the number of carbamate groups in the cellulose chain. It has been found that the carbamate groups increase the sensitivity of the fibres to water and, simultaneously, they impair the wet properties of the fibres. In some cases, this is even an advantage, whereas in other cases it is detrimental because, for instance in textile uses, the fibres are most often expected to have good wet strength.
The object of the present invention is a procedure by which the properties of cellulose carbamate fibres, in particular their wet properties, can be regulated as desired so that fibres suitable for each purpose are obtained. The procedure according to the invention for regulating the properties of cellulose carbamate fibres is characterized in that the fibres are treated with alkali or with an organic base.
By the aid of an alkali treatment according to the invention, the carbamate groups of the cellulose carbamate can be removed to the desired degree. Thus for instance the wet strength of the fibres substantially increases, while the wet stretchability decreases. If, again, for instance fibres for non-woven purposes are desired which have good water absorption capacity and swelling capacity, the alkali treatment of the invention may be carried out in a milder form. It is possible to carry the alkali treatment of cellulose carbamate fibres so far that a near complete removal of the carbamate groups from the fibres takes place. A fibre has then been obtained of which the solubility in alkali has gone down to the same level
REFERENCES:
patent: 3560139 (1971-02-01), Suminokura et al.
patent: 4404369 (1983-09-01), Huttunen et al.
patent: 4456749 (1984-06-01), Mandell et al.
patent: 4486585 (1984-12-01), Turunen et al.
Eklund Vidar
Ekman Kurt
Huttunen Jouko
Mandell Leo
Turunen Olli
Czaja Donald
Lorin Hubert C.
Neste Oy
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