Plastic and nonmetallic article shaping or treating: processes – Forming continuous or indefinite length work – Shaping by extrusion
Patent
1997-03-26
1998-08-18
Tentoni, Leo B.
Plastic and nonmetallic article shaping or treating: processes
Forming continuous or indefinite length work
Shaping by extrusion
1062001, 1062002, 1062003, 1062021, 26421113, 26421114, D01F 202
Patent
active
057955220
DESCRIPTION:
BRIEF SUMMARY
INTRODUCTION
The present invention is concerned with a new cellulose moulded body and a process for the production of this cellulose moulded body. Particularly, the present invention is concerned with a new cellulose fibre and a new cellulose film having a predetermined tendency to fibrillation.
BACKGROUND OF THE INVENTION
As an alternative to the viscose process, in recent years there have been described a number of processes wherein cellulose, without forming a derivative, is dissolved in an organic solvent, a combination of an organic solvent and an inorganic salt, or in aqueous saline 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.
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, in the following referred to as amine-oxide process, a tertiary amine-oxide, particularly 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.
A typical feature of the Lyocell fibres is their pronounced tendency 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. The reason for fibrillation 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 5.5.
WO 92/07124 also describes a process for the production of a fibre having a reduced tendency to fibrillation wherein the never dried fibre is treated with a cationic polymer. As such a polymer, a polymer having 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.
In a lecture given by S. Mortimer at the CELLUCON conference in 1993 in Lund, Sweden, it was mentioned that the tendency to fibrillation rises as drawing is increased.
There have been published already some methods to reduce the tendency to fibrillation of Lyocell fibres:
Thus from WO 95/02082 of the applicant it is known that fibrillation may be reduced by certain combinations of spinning parameters.
Moreover, it is known that the fibrillation properties of Lyocell fibres may be improved by chemical crosslinking. Thus, e.g. EP-A - 0 538 977 describes crosslinking of Lyocell fibres with chemical reagents able to react with cellulose in a state before any drying, i.e. when the fibre is produced, as well as in a dried state, i.e. substantially during finishing of the textile fabrics.
Crosslinking Lyocell fibres during finishing has the main drawback for the finishing operator of requiring additional steps which cause additional costs. Also, the application of such additional steps limits the variety of produceable textile fabrics, which again restricts the marketing possibilities of the Lyocell fibres. Another essential disadvantage of the treatment of Lyocell fibres after a first drying consists in that the susceptibility of the fibres for crosslinking chemicals is significantly reduced, particularly after the first drying, as compared to the state they exhibit when they are freshly spun. This requires the use of greater amounts of chemicals.
The crosslinking reagents exemplified in the above patent applic
REFERENCES:
patent: 4246221 (1981-01-01), McCorsley, III
Abstract of WO 92/14,871 (Published Sep. 3, 1992).
Abstract of WO 95/2,082 (Published Jan. 19, 1995).
Abstract 80791j, Chemical Abstracts vol. 66, pp. 7572 (1967) (discussing-Italian patent application 690,926 (Jun. 24, 1965).).
"Chemical Aftertreatment of Textiles" pp. 414 (H. Mark, N.S. Woodug, S.M. Atlas editors), (Wiley Interscience New York).
Lewis "New possibilities to improve cellulosic fibre dyeing processes with fibre-reactive systems" JSDC vol. 109 (Nov. 1993).
Lewis et al., "New methods for improving the dyability of cellulose fibres with reacive dyes" JSDC vol. 107 (Mar. 1991).
Bartsch Peter
Firgo Heinrich
Koll Berndt
Mulleder Eduard
Seidl Sigrid
Lenzing Atkiengesellschaft
Tentoni Leo B.
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