Coating processes – Coating by vapor – gas – or smoke – Base includes an inorganic compound containing silicon or...
Patent
1997-06-16
1998-07-14
Cameron, Erma
Coating processes
Coating by vapor, gas, or smoke
Base includes an inorganic compound containing silicon or...
4272555, 81275, 812751, 81281, 81492, B05D 100
Patent
active
057801070
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a method for prosing fabric incorporating fibres of keratin to impart shrink-resistance to the fabric. The term "fabrics" is used herein to mean any assembly of fibres such as woven wool, top (aligned fibres), web or yarn.
It is well known that keratin fibres such as wool have a tendency to shrink during laundering. The shrinkage of wool during laundering is a result of the surface cuticular structure of th fibre. It is known to overcome this problem by treating the wool to reduce or eliminate the "directional frictional effect". Shrink resistance can be achieved by making use of three basic approches: fibres during laundering.
Chemical modification has been achieved in the past using a variety of processes but the most popular process relies upon chlorination. In particular it is well known to pass a fabric through a fluid including chlorine and subsequently to apply to, the chlorinated fabric a shrink proofing polymer. This approach is very effective and economic but as it is a "wet" finishing treatment some form of effluent processing is required It is becoming highly undesirable to have to dispose of absorbable organohalogens into the water supply and thus the traditional chlorination route is becoming less and less acceptable.
Corona discharge is a well known and widely used alternative to chlorination for achieving shrink resistance. This process involves the bombardment of the fabric surface with high energy electrons which are of sufficient energy to break covalent bonds in the fibres. In addition, collision between electrons and components of the air results in the formation of ozone and nitrogen oxide. Subsequent reaction between free valent species on the fibre surface and the corona atmosphere leads to the formation of a polar surface encouraging wetting and adhesion of subsequently applied polymer surface treatments. Amino acid analysis of cuticular protein indicates the formation of cysteic acid. Corona treatment has been shown to improve shrink resistance, yarn tensile properties, spinnability and wettability, and treated fabrics or yarns exhibit superior dyeing properties. Improvements in shrink resistance and spinnability have been attributed to an increase in fibre friction.
Thus electrical discharge does provide an alternative to conventional chlorination but unfortunately is economically unattractive as the process is relatively slow, reducing the maximum rate of production of treated fabric, and in addition cannot successfully treat fibres within bulky fabrics, e.g. wool top.
In 1946, Hudson and Alexander demonstrated that gaseous fluorination could be used to impart shrink resistance to wool. Subsequently a reference was made to their work in the general text book "R F Hudson and P Alexander, "Wool: Its Chemistry and Physics", Pub. Chapman and Hall, London, Sec. Ed., (1963)". The treatment times suggested by this work, however, indicated that a fabric to be treated had to be resident within a chamber containing fluorine gas for long periods, for example 20 minutes. Thus, fabric was treated in batches and continuous treatment of fabric was not possible. In addition, high concentrations of fluorine gas were required, for example 20% fluorine. Finally, it was stated that the wool had to be pre-dried before treatment. These requirements, particularly the required residence times and the required pre-drying, make it completely uneconomic to rely upon fluorination as described in the published documents.
It is an objective of the present invention to obviate or mitigate the problems outlined above.
According to the present invention, there is provided a method for pre-treating a fabric incorporating fibres of keratin to impart shrink-resistance to the fabric, wherein the fabric is passed continuously through a chamber containing an atmosphere of fluorine gas at a rate such that the residence time of the fabric within the chamber is 60 seconds or less.
Thus, in contrast with the published fluorination method, fabric is passed continuously through an atmospher
REFERENCES:
patent: 4508781 (1985-04-01), Yagi et al.
Vol. 41, 1947 Chemical Abstracts, Columbus, Ohio, U.S.; R.F. Hudson et al.: "The action of fluorine and fluorides on wool" col. 1447; 1946.
May, 1946 Society of Dyers and Colourists "The Action of Fluorine and Fluorides on Wool" by R.F. Hudson and P. Alexander pp. 193-198 1946.
Landwehr, Textile Research Journal, Aug. 1969, pp. 792-793.
Carr Christopher Michael
Dodd Kevin James
Cameron Erma
The University of Manchester Institute of Science and Technology
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