Plastic and nonmetallic article shaping or treating: processes – Forming continuous or indefinite length work – Shaping by extrusion
Patent
1995-06-05
1997-08-05
Tentoni, Leo B.
Plastic and nonmetallic article shaping or treating: processes
Forming continuous or indefinite length work
Shaping by extrusion
1062003, 264233, B29C 4700, D01F 224
Patent
active
056539312
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention is concerned with a process for the production of cellulose moulded bodies, in particular films and fibres, by extruding a solution of cellulose in a tertiary amine-oxide through a shaping device, e.g. a film forming gap, or through spinning holes of a spinneret, and conducting the extruded solution while drawing it into an aqueous precipitation bath, in which it coagulates, whereafter the coagulated moulded body is washed with an aqueous washing liquid. Furthermore, the present invention is concerned with a composition for moulding or spinning containing cellulose, a tertiary amine-oxide and a non-solvent, particularly water.
As an alternative to the viscose process, in recent years there has been described a number of processes in which cellulose, without derivatization, is dissolved in an organic solvent, a combination of an organic solvent and an inorganic salt, or in aqueous salt solutions. Cellulose fibres made from such solutions have received by BISFA (The International Bureau for the Standardisation of man made Fibres) the generic name Lyocell. As Lyocell, BISFA defines a cellulose fibre obtained by a spinning process from an organic solvent. By "organic solvent", BISFA understands a mixture of an organic chemical and water. "Solvent-spinning" is considered to mean dissolving and spinning without derivatization.
So far, however, only one process for the production of a cellulose fibre of the Lyocell type has achieved industrial-scale realization. In this process, N-methylmorpholine-N-oxide (NMMO) is used as a solvent. Such a process is described for instance in U.S. Pat. No. 4,246,221 and provides fibres which exhibit a high tensile strength, a high wet-modulus and a high loop strength.
However, the usefulness of plane fibre assemblies, for example fabrics, made from the above fibres, is significantly restricted by the pronounced tendency of the fibres to fibrillate when wet. Fibrillation means the breaking up of the fibre in longitudinal direction at mechanical stress in a wet condition, so that the fibre gets hairy, furry. A fabric made from these fibres and dyed significantly loses colour intensity as it is washed several times. Additionally, light stripes are formed at abrasion and crease edges. The reason for fibrillation (splicing) may be that the fibres consist of fibrils which are arranged in the longitudinal direction of the fibre axis and that there is only little crosslinking between these.
WO 92/14871 describes a process for the production of a fibre having a reduced tendency to fibrillation. The reduced tendency to fibrillation is attained by providing all the baths with which the fibre is contacted before the first drying with a maximum pH value of 8.5.
WO 92/07124 also describes a process for the production of a fibre having a reduced tendency to fibrillation, according to which the never dried fibre is treated with a cationic polymer. As such a polymer, a polymer with imidazole and azetidine groups is mentioned. Additionally, there may be carried out a treatment with an emulsifiable polymer, such as polyethylene or polyvinylacetate, or a crosslinking with glyoxal.
BRIEF DESCRIPTION OF THE PREFERRED EMBODIMENTS
According to EP-A - 0 538 977, the tendency to fibrillation of cellulose fibres can be reduced with bireactive dyes.
SUMMARY OF THE INVENTION
Further, it has been known already since 1983 that the tendency to fibrillation of fibres spun from an NMMO/cellulose-solution can be reduced by treating them with glyoxal (see M. Dube and R. H. Blackwell, Tappi Proceedings 1983 International Dissolving and Speciality Pulps, pages 111-119).
SUMMARY OF THE INVENTION
It has been shown that the known cellulose moulded bodies, such as cellulose films and cellulose fibres, of the Lyocell type still leave something to be desired in terms of tendency to fibrillation, and thus it is the object of the present invention to provide a process for the production of cellulose moulded bodies, in particular cellulose films and cellulose fibres
REFERENCES:
patent: 4246221 (1981-01-01), McCorsley, III
patent: 4261943 (1981-04-01), McCorsley, III
M. Dube and R.H. Blackwell, Tappi Proceeding, 1983, International Dissolving & Specialty Pulps, pp. 111-119.
Handbuch der Textilhilfsmittel, Verlag Chemie, 1977; ISBL 3-527-25367-X.
Eibl Markus
Firgo Heinrich
Lenzing Aktiengesellschaft
Tentoni Leo B.
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