EP0186644B1 - Process for preparing textile materials undetectable by infrared rays - Google Patents

Abstract

Lampblack is added to an otherwise conventional aqueous textile resin finishing solution to render the textile undetectable by infrared radiation detection. The lampback is preferably dispersed in a resin used in the aqueous solution.

Description

The present invention relates to a process making it possible to obtain textile materials which cannot be affected by infrared radiation.

The method according to the invention makes it possible to obtain textiles which, subjected to detection by infrared radiation, either by photography or by electronic detection optical devices, absorb these radiation, which makes them invisible to these methods of detection.

Its most important application is in articles intended for military purposes, since it is particularly essential and is frequently used for its camouflage properties.

Currently, only two processes are known for which there is information in the textile field, one from the United States of America and the other from France, which is implemented thanks to the incorporation of black. smoke in the doughs intended for the preparation of the polyester filament, which is subsequently transformed into fiber ready for textile use.

There is DE-A-1935636, which is used to obtain a harder protective element, without flexibility and therefore not suitable for clothing, in which the treated fabric will obtain a black color and the method of which is an embodiment expensive because it is subject to various padding operations.

With the present invention, a more economical process is obtained, with a single padding operation which gives rise to a flexible fabric, in which the original color of the fabric is respected.

In the present invention, the adhesive used in DE-A-1935636 is eliminated.

The process which is the subject of the present invention allows the incorporation of smoke black into any class of textile fibers, whether natural, synthetic or artificial, in any phase of their textile production, namely, flock, combed, thread or fabric, regardless of the color, the texture of the weave or the mixture of fibers between them. In general, the process is based on obtaining smoke black in dispersion in textile finish resins, modifying this finish or not, so that subsequently, upon incorporation in an aqueous bath. , the smoke black particles are kept in the finely dispersed state. In this way, after obtaining the aqueous solution and with the particles in the dispersed state, they can be deposited on the textile substrate by means of an impregnation and wringing process with drying and subsequent polymerization or by exhaustion, thanks to hydrolysis of the bath to slightly acidic pH.

The novelty brought by this process is obvious, since, until now, it is the first time that the use of smoke black in the textile field, not in the manufacture of fibers, is done for camouflage purposes. .

On the other hand, the smoke black can be deposited, which constitutes a new improvement, on any textile fiber in an aqueous medium, by a process such as that traditionally used in the textile industry for the transformation and finishing of textiles.

The smoke black is insoluble and, with this process, stable aqueous dispersions are obtained allowing their industrial use. It should also be noted that the smoke black deposited as dust in textiles will not remove the resistance or solidity to the requirements enabling most DIN or ISO textile standards, and commonly accepted in the textile field, to be satisfied, such as resistance to rubbing, dry cleaning and washing, and other specifically industrial standards to which textiles are subjected during their fabric development process. With the process according to the present invention, the resin makes it possible not only to obtain a dispersion of easy industrial use, but also, after drying and polymerization, it performs the function of crosslinking agent which makes the adhesives particles in textiles and covers them in the form of a very thin film, giving them the same resistance or solidity as those presented by the resin, with regard to the particular requirements that textiles must have, which is obtained by or several textile finishing resins, depending on the type of finish required by the textile, depending on the development phase during the race or what ultimately needs to be achieved.

Another important novelty of the invention is the possibility of practicing deposits of quantities in various percentages on the textile, according to the degrees of immunity to detections by infrared light, without this fabric being substantially altered, nor to the touch neither with regard to color to any appreciable degree.

With the process according to the invention, fabrics or textiles are obtained in any state of development, which, subjected to lighting or to the action of light or infrared sources, more particularly in extreme red, is that is to say greater than about 700 nanometers, absorb these radiations without being detected by the means that are usually used for such detection, for example with photographic films for infrared in white and black and color films, the maximum detection is close to around 1200 nanometers, which is equivalent to an awareness zone of between 6500 and 8500 A. The same thing happens with devices that combine optics and electronics to make this radiation visible at first sight .

The process according to the invention is generally the following.

Smoke black is used from a very pure variety of amorphous carbon, with a composition comprising 98-99% carbon and 2 to 3% hydrogen. This smoke black is obtained by a properly regulated combustion with limited quantities of air, fatty oils, gou drons, petroleum, turpentine, etc., according to what may be suitable from what exists on the market.

The powdered smoke black thus obtained is insoluble in an aqueous medium, so that it is difficult to apply it in the textile industry and, to avoid this drawback, the process described below is followed: a paste is formed with a concentrated resin until a homogeneous and stable dispersion is obtained, using for this purpose the dispersants and emulsifiers which the resins contain in a commercial form.

After this phase of pulping, the resin used for pulping is dissolved in an aqueous solution, by continuous stirring, until it is used as a primer.

The impregnation of the textile is done by the padding and wringing process, or by exhaustion, as will be explained in detail below. Then, drying is carried out, at a temperature which must be between 50 and 90 ° C. depending on the textile which is being treated.

Finally, the polymerization is carried out, the operation of which must be carried out according to the resins used as a support for the smoke black, but which, in general, must be carried out at 130-140 ° C. and over a period of 3 5 minutes. Drying and polymerization are both common to all the processes which will be described.

Resins to be used:

Résines-Le choix des résines d'apprêt à utiliser comme dilaunts et supports du noir de fumée dépendra du fini que l'on désire obtenir, en tenant compte que doivent être satisfaites les exigences de chaque cas, déterminées par les divers types de textiles ou de de tissus suivant le cas, qu'il s'agisse de vêtements, de fils pour travaux de pièces de protection, de gabardines, etc. Après de très nombreux essais, on a obtenu les meilleurs résultats avec les résines et les concentrations de noir de fumée que l'on détaille ci-après.the use of resins ensures a double function: on the one hand, it allows the dispersion or the emulsion, according to the case, of the powder of black of smoke, which allows to apply it in an industrial way with the tools traditional employee in the textile industry. On the other hand, these resins constitute an appropriate crosslinking agent to obtain the following resistances required for parts and textile materials of common use:

Resins- The choice of primer resins to be used as dilaunts and supports for smoke black will depend on the finish that is desired, taking into account that the requirements of each case must be satisfied, determined by the various types of textiles or fabrics as appropriate, whether clothing, threads for work of protective parts, gabardines, etc. After numerous tests, the best results have been obtained with the resins and the concentrations of smoke black which are detailed below.

Touch-changing primers

Urea-formaldehyde and melamine-formaldehyde resins, up to 15 g / I and 0.5 g / I of fume black respectively.

Polyvinyl chloride resins and acrylic resins, up to 25 g / I and 0.5 g / I of smoke black respectively.

Polysiloxane resins and other ionic softeners, up to 1.5% and 0.3% smoke black, based on the weight of the fiber, by exhaustion at 40 ° C and at pH 5.5 with cations.

Waterproofing

Silicone and also polysiloxanes, up to 50 g / l and 1 g / l of smoke black respectively (silicones and polysiloxanes, as we have just mentioned).

Chromium salts in isopropyl alcohol: up to 50 gll and 0.7 g / I of smoke black respectively.

Zirconium salts and chlorinated paraffins, up to 50 g / I and 1 g / I of smoke black respectively.

This was continued by testing other types of resin to determine their strength and application results.

All the tests carried out and to be carried out aim at incorporating smoke black in textiles, with guarantees of resistance or solidity and easy to apply, as has never been used until now in industry textile in order to obtain textiles that absorb infrared radiation above 700 nanometers, which is why these textiles are easy to camouflage with detections made thanks to photographs with infrared-sensitive films, an optical and electronic combination in a range between 600 and 1250 nanometers, and a tolerance zone obtained with the Beckman spectrum is also obtained.

Claims (2)

1. A process for the production of textiles not detectable by means of infra-red radiation, wherein there is a filler with smoke black or of its derivatives, with resins or polymers. The latter are present in larger quantities than the smoke black and filler, and are concentrated until obtaining a homogeneous and stable dispersion which, at the same time, has an affinity with textile fibres. The resin used for the filler is then dissolved in an aqueous solution, with continuous agitation, and the textile material is then impregnated with a single padding operation, followed by a draining process. The textile is dried at temperatures between 50 and 90°C, depending on the textile material to be treated. The resin used in the impregnation is then polymerized, with the dry fabric being submitted to temperatures of 130 to 170°C for 3 or 5 minutes, so as to obtain a larger molecule giving flexible solidity to the textile.

2. A process as set forth in claim 1 wherein the textile is impregnated in the aqueous solution of the filler obtained with the smoke black and the resin or the polymer can also be made by means of dripping, followed by drying and polymerization.