Method of dyeing high performance fabrics

Abstract

There is provided a process of dyeing yarn or cloth comprising fibres, comprising dyeing at least part of the fibres with at least two types of dyestuff that dye the same fibres substantially the same colour. One of the types of dyestuff chemically bonds with or is at least partially incorporated into the fibre structure and the other type of dyestuff does not chemically bond with or become at least partially incorporated into the fibre structure.

Description

CROSS REFERENCE TO RELATED APPLICATIONS[0001]This application is a continuation of international application no. PCT / EP2009 / 051416 filed on 6 Feb. 2009, which was published under PCT Article 21(2) in English, and which claims priority from GB application number 0802170.1 filed on 6 Feb. 2008, the contents of which applications are hereby incorporated by reference in their entirety.BACKGROUND OF THE INVENTION[0002]1. Field of the Invention[0003]The invention relates generally to procedures for dyeing yarn, cloth or fibres (particularly for dyeing cloth) and in particular to procedures for providing greater colour durability. The invention also relates to textiles treated according to the inventive procedures, and to garments comprising such textiles.[0004]The present invention finds particular application in dyeing yarn, cloth or fibre that is inherently difficult to dye with dyes that offer adequate light fastness, and can only be well dyed with dyes that are subject to poor light f...

AI Technical Summary

Benefits of technology

[0035]A yarn or cloth comprising fibres dyed with only one of the dyestuffs suffers from either poor light fastness or poor wash / abrasion resistance. In contrast, a yarn or cloth dyed in accordance with the present invention shows improved light fastness and wash resistance. This is believed to result from the culmination of the complementary properties of the two dyestuffs.

[0067]An alternative and particularly interesting procedure, to those discussed above, that may be used to apply one or both of the dyes is a digital application technique. Such techniques are described in detail in PCT application Nos PCT / EP2004 / 010732 and PCT / EP2004 / 010731 both filed on 22 Sep. 2004 the contents of which are hereby incorporated by reference in their entirety. A further apparatus and procedure is disclosed in PCTEP2008 / 064838 filed 31 Oct. 2008, also incorporated herein by reference. An advantage of these techniques is the accuracy of drop placement that can be achieved, whereby precise quantities of each dyestuff may be deposited at a given point on a substrate from two different deposition arrangements. Deposition may also take place onto both sides of a substrate. Furthermore, since the deposition can be precisely controlled, different colours may be deposited at different locations on the substrate allowing printing of designs and patterns according to the invention whereby each area of the substrate is effectively dyed twice with the same colour according to the two different mechanisms. The dyeing step may also be integrated with one or more digital finishing steps e.g. as described above.

Problems solved by technology

However, the very highly crystalline structure of the aramid fibres, which gives such desirable physical properties, lowers the accessibility of the fibre to dyeing polymer molecules.

This means that the fibres are difficult to dye and can only be dyed with a very limited number of dyestuff types using special procedures.

Although the dyestuffs used in the above procedures are able to bond well to the aramid fibres they suffer from a poor light fastness.

Solution dyed fibres are more costly than the undyed fibres due, in part, to the additional costs of manufacture, and must be used in the colour provided by the supplier, leaving the weaver with only a limited choice of colours.

None of the above-mentioned processes provides sufficient light fastness properties for aramids.

The current aramid colouring technology hence suffers from the problem that aramid fabrics tend to lose their colour rapidly due to a poor light fastness of the commonly used dyestuffs in exhaust dye systems.

Such fading is a serious problem because it typically leads to unacceptably rapid decolouration of the fabric giving a poor appearance.

In extreme cases the lack of light fastness can lead to appreciable colour loss even prior to sale of a garment.

An alternative method of dyeing aramid fabrics is to use pigment dyestuffs, however these dyestuffs are not used commonly.

Predominantly because they do not bond well to the fibres, yarn or cloth and are easily removed by abrasion.

Hence, they lack wash fastness in general.

The result is that too great a colour loss results through washing of a pigment dyed aramid garment.

An example of another field in which colour durability is a particular problem is the field of high visibility dyeing.

Yarn, cloth or fibres that is dyed with high visibility dye suffers from the problem of poor colour retention because the high visibility dyes lack adequate light fastness, and hence fade within in an unacceptably fast period of time.

A poor colour durability is thus of a particular concern in high visibility applications (in particular high visibility clothing) because the product can only be used while it retains suitably strong colouring to be conspicuous.

A loss of high visibility colour either leads to dangerous situations in which the clothing is no longer easily visible, or the clothing has to be replaced at significant cost.

Additionally, since high visibility clothing is often worn outside, a poor light fastness is of particular concern, since the clothing may be exposed to sunlight for extended periods.

Thus there exists a problem in the field of high visibility dyeing that dyed yarn, cloth and fibre shows a poor light fastness.

This is a particular problem for high visibility clothing applications.