GB1392390A - Process for dyeing webs of textile material - Google Patents

Abstract

1392390 Dry dyeing and optical brightening of webs of textile material SUBLISTATIC HOLDING SA 16 June 1972 [18 June 1971 24 May 1972] 28394/72 Headings D1B and DIP A process for the continuous dyeing or optical brightening of webs of textile material made of synthetic fibres comprises dry heating the webs at 175‹-220‹C in contact with a flexible support uniformly coated or impregnated with a uniform layer of a dyestuff or optical brightening agent sublimable or vapourizable at the said temperature, either the temperature or both the temperature and the duration of the dry heating being constantly regulated to maintain level transfer of the dyestuff or optical brightener from the support onto the web. A central control mechanism is used to adjust the temperature and, when desired, the heating duration, and such a mechanism will generally have switch positions which correspond at least to the desired number of shades of colour. It is also possible gradually to alter the duration of the heating, which preferably can be repeated any number of times so that a spectrum of intensities of colour is obtained. Striped patterns may be produced in this way, and these may also be obtained by temperature variation. Level dyeings of any desired shade of colour may also be produced from only one sheet uniformly coated or impregnated with the colour. Thus a dark colour may be used to produce dark, medium and light shades. The process is preferably performed on a machine which has a rotating surface such as a roller which is permeable to air and is connected to a vacuum device. In such machines flexible supports which are either impermeable or permeable to air can be used and in the latter case it is advisable to use a device which creates sufficient vacuum to draw the pervious paper onto the textile web. In such machines the evacuated cylinder may be provided with several heaters disposed across the width of the dyeing surface. British Specification 1312529 describes one machine of this type. It is preferred that the air-permeable cylinder has a large number of perforations, preferably at least 3 per sq. cm., and a cylinder made from foam-like bronze is particularly suitable. The perforated cylinder may be provided with a heat-resistant coating e.g. made from fabric or fleece materials. The flexible support is preferably of paper or aluminium and is coated by known methods. A paper support may be coated with a varnish to make it impermeable to air. Heating may be by infra-red or high frequency irradiation. Polyamide, polyester (e.g. linear polyesters such as polyethylene terephthalate), polyacrylonitrile and polypropylene fibres may be dyed and the process is particularly suitable for dyeing knitted fabrics or tightly packed materials such as carpeting, velvet or imitation fur fabrics. 'Disperse anthraquinone and quinophthalone dyes are used in the Examples.