Stock material or miscellaneous articles – Coated or structually defined flake – particle – cell – strand,... – Rod – strand – filament or fiber
Patent
1995-08-28
1997-03-11
Edwards, Newton
Stock material or miscellaneous articles
Coated or structually defined flake, particle, cell, strand,...
Rod, strand, filament or fiber
428393, 536 56, 536 57, D02O 300
Patent
active
056099576
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to delustered regenerated cellulosic fibers and has particular, but not necessarily exclusive, reference to delustered regenerated cellulosic viscose rayon fiber.
2. Description of the Related Art
Regenerated cellulosic material may be produced by the well-known viscose rayon process which is described, for example, in the book "Man Made Fibers" by R.W. Moncrieff published by Heywood Books, London, England, Fifth edition 1970, pages 152 to 207. The term "viscose rayon" is also used herein to cover high tenacity cellulosic fibers, such as Modal fibers, and polynosic rayons, see Moncrieff pages 252 to 277. The contents of the two portions of the Moncrieff book are incorporated herein by way of reference.
More recently there has been commercialization.
In the viscose rayon fiber process as is described in Moncrieff a compound of cellulose --cellulose xanthate -- is produced in an alkaline solution. The cellulose xanthate solution is then spun or extruded through a suitable jet into a regeneration bath to form filaments. Typically the regeneration bath contains sulphuric acid and other additives. In the regeneration bath the cellulose xanthate is converted into cellulose filaments. These filaments are cut to form staple fiber. Staple fibre is typically produced from jets with large numbers (tens of thousand or more) of individual holes.
More recently processes have been evaluated whereby cellulose is taken into a true solution in a solvent, such as an aqueous N-methyl morpholine-N-oxide and the solution of cellulose forms a dope which is extruded through a suitable jet into a spin bath, where the solvent is leached out to regenerate the cellulosic material. An example of such fiber is the recently available cellulose fiber which has been given the generic name lyocell by BISFA (The International Bureau for the Standization of Man-Made Fibres).
Although the viscose rayon production process is extremely well known and no further explanation need be provided of the process as such, the cellulose solution process is more recent. A suitable process for the production of lyocell cellulosic fiber is described in U.S. Pat. No. 4,416,698, the contents of which are incorporated herein by way of reference.
In many cases it is desirable to produce regenerated cellulose fiber which has a delustered appearance. Conventionally, such a delustered appearance has been provided by the incorporation of titanium dioxide into the dope to be spun to produce the fiber (see Moncrieff page 162). Titanium dioxide is an inert pigment which delusters the fiber very satisfactorily. Unfortunately, however, the production of titanium dioxide gives rise to potential pollution problems. Titanium dioxide is very abrasive and, further, may catalyze photodegradation of cellulose. This abrasiveness can lead to considerable wear in the manufacturing plant used to produce the regenerated cellulosic fiber and also in the plant used to process the fiber. In such circumstances, the titanium dioxide incorporated into the fiber acts as an abrasive or polish, abrading the equipment used to process the fiber. The disadvantages of titanium dioxide as well as the advantages, are described in Moncrieff pages 698 to 699, the contents of which are incorporated herein by reference.
Although there are problems with the use of titanium dioxide as a delustrant, on balance the benefits of the use of titanium dioxide are such that it is the most frequently used commercial delustrant, as far as the applicants are aware.
Numerous other materials have been proposed as delustrants for regenerated celluloses.
In U.S. Pat. No. 3,833,021 there is disclosed the use of droplets of colloidal size to act as a delustrant not for fibers but for regenerated cellulose sausage casings. In the description of the prior art in U.S. Pat. No. 3,833,021 there is an extensive summary of the delustrants which have been used previously in regenerated cellulose products. Thus U.S. Pat. No. 3,833,021 refers to the fo
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Page Stuart
Probert Paul L.
Courtaulds PLC
Edwards Newton
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