US2149750A - Process for the production of waterproof fabrics permeable to air - Google Patents

Description

Ma h 7, 1939.

PROCESS FOR THE PRODUCTIOfi 0F WATERPROOF FABRICS PERMEABLE TO AIR Filed Nov 6, 1936 fl'lliefihr: M z a man -M... 7,1939

v 2,149,750 PATENT OFFICE PROCESS FOR THE PRODUCTION OF WA- TERPROOF FABRICS PERMEABLE TO AIR Fernand Frederic Schwartz, Paris, France, as-

signor, by direct and mesne assignments, to American Ecla Corporation, Dover, Del., a corporation of Delaware Application November 6, 1936, Serial No. 109,604

In France November 15, 19 35 4 Claims. (Cl. 91-70 (b) The nature of the water-insoluble product.

This invention is fora process for the production of waterproof fabrics permeable to air.

.Fabrics possessing to some degree the property of impermeability to water and permeability to air have previously been produced, for example by impregnating them with substances'such as aluminium acetate. Such a treatment has, however, only been applied to thick fabrics and it has never been possible heretofore to obtain satisfactory results With-thin fabrics.

In nature there are to be found numerousexamples of substances satisfying the two conditions mentioned above of impermeability to water and permeability to air and in this respect the plumage of aquatic birds is remarkable. The permeability to air of the plumage-is ensured by oblique interstices of very small dimensions varying from ,5 0 to 1000 Of a square millimetre in area. Air passes readilythrough these interstices while water is prevented from passing through them on account of its surfacetension.

Heretofore, it has not been possible to. attain results even remotely comparable with those found in nature. V v

It will be clear that. if an elastic water-insoluble substance such as rubber is applied to a fabric of very close texture the pores of the fabric will be completely closedv and thefabric will cease to be permeable to air. If,'on the other hand, a fabric is employedwhich has large spaces between the warp and weft threads, these spaces will not be materially reduced in size by' the application of rubber dispersions or solutions and impermeability of the fabric to water will not be achieved.

It is an object of the present invention to produce a fabric which permits air to pass therethrough but is water-impermeable by applying to the fabric a plastic or elastic water-insoluble substance in such a manner that the interstices are reduced in size to such a point that water is no longer capable of passing through them.

The water-insoluble plastic or elastic substance applied to the fabric is preferably one which iscapable of adhering tenaciously to the fibres and be varied at will:-

(a) The degree of closeness of weave of the.

between drain rolls ii and isthen dried, the dryfabric,

Of the above-mentioned factors, pressure plays I a very important part. A slight pressure does not appreciably modify the size of the interstices of the fabric, while too great a pressure leads to the closing of the interstices completely and. hence renders the fabric impermeable to air. The precise magnitude of the pressure-is of course itself dependent upon the various other factors mentioned above.

Among the substances which may be applied with advantage to the fabric rubber or a product derived'therefrom is preferred. This material is not only water-insoluble but possesses the properties of elasticity and plasticity in markeddegree when fresh.

In one method of applying the invention, rubber may be applied to the fabric in the form' of rubber latex containing vulcanizing and subsidiary reagents, the fabric to be treated being immersed in a bath of this liquid.

Alternatively, instead of immersing the fabric in the liquid, the liquid may be applied to the fabric e. g. by coating or spraying. The fabric, or the threads or fibres of which it is composed, may be subjected to a process of impregnation prior to applying the present invention.

Following is a description by way of example only and with reference to the accompanying diagrammatic drawing of methods of carrying the invention into effect.

In the drawing- Figure 1 shows the application of water-insoluble material to a fabric bypassing it through a bath, the fabric being subsequently dried and submitted to pressure,

Figure 2 shows the treatment of fabric by immersion in successive baths,

Figures 3 and 4 show the application of a water-insoluble substance by spraying and by spreading respectively, and

Figures 5 6 and '7 show portions of fabric on an enlarged scale showing the fabric (a) before treatment with the water-insoluble substance, (b) after treatment with the water-insoluble substance but before pressing and (c) after pressing,

respectively. I i I v Similar parts are denoted by similar reference numerals throughout thedrawing. i

In Figure -1 the web of fabric I l is passed fro a roll I! under a roller IS in a bath I4 containing an impregnating liquid ii. The fabric vipasses ;vided with roller I3, and drain rolls I6. The

fabric leaving the last bath is dried. The drying operation may complete the process or the fabric may be further subjected to a pressing operation as in Figure 1.- r

Figure 3 shows a web of fabric I I being treated with a water-insoluble substance applied thereto by means of a spray gun I II, the fabric then passing to the drying and pressing operations shown in Figure 1. In Figure 4 the water-insoluble substance is applied to the web of fabric by means of a roller I I8 supplied with the substance from a bath I9.

In Figure 5 threads 20 of a fabric permeable to water are shown on an enlarged scale. Figure 6 shows the same threads now carrying a relatively thin coating of water-insoluble substance, the fabric being still permeable to water. Figure 7 shows the same threads after pressure, and if necessary heat, has been applied. .In this case the interstices of the fabric have been reduced in size to such an extent that the fabric is impermeable to water.

In one specific method of carrying out the invention a cotton fabric was employed having 45 warp threads and 30 weft threads per centimetre and weighing 160 grms. per square metre, the interstices between the threadsbeing from /5 to 1 5 square millimetre in area. The fabric was immersed in a bath of rubber latex to which had been added vulcanizing and subsidiary reagents of such nature and in such amount that vulcanization would take place in two minutes at 150 C. The quantity of rubber added to the fabric amounted to about 5 to 20% (as dry rubber) on theinitial weight of the fabric. The amount of rubber latex introduced into the fabric is controlled by adjustment of the pressure produced on the fabric by means of a pair of drain rollers through which the dipped fabric is passed. After- .taining the fabric for the necessary time-in an autoclave" or by any other method.

It should be noted that in the example given above the fabric, after leaving the latex bath and after being drained and dried, is still permeable to water (see Figures 5 and '6) the interstices retaining their original dimensions or substantially their original dimensions. When, however, the fabric has been calendered a crushing or lateral spreading of the threads of the impregnated fabric takes place and this'results in a diminution in the size of the interstices (see Figure '7) the fabric being then impermeable to water while remaining permeable to air;

By use of the present invention it is possible to adjust the degree of permeability to air of any particular fabric while ensuring the total imperto fabrics of any thickness but is particularly valuable .for the treatment of thin fabrics.

Instead of employing rubber for the treatmentof the fabric it is possible to employ other plastic, thermoplastic or elastic substances such as for example waxes or synthetic resins. The conditions under which these substances are applied (including proportions, temperatures, pressin'es, etc.) may be selected according to the nature of the fabric and the water-insoluble material with which it is to be impregnated.

It is within the scope of the present invention to reduce the size of the interstices of the. fabric by methods other than by pressure. Thus the contraction of the interstices may be effected by immersing the fabric in successive baths so as to deposit on the threads, layers of water-insoluble material until the interstices are reduced in size to the point at which they prevent the passage of water therethrough (see Figure 2).

The methods and means described above for the treatment of textile materials are given by way of example only and not by way. of limita tion.

I claim: v 1. A process for the production from a. woven or knitted textile material which is permeable" both to air and water of a textile product which through the interstices of the treated textile material, then drying the latex-treated textile material, and thereafter applying mechanical pressure and heat to the faces of the treated textile material to permanently deform and vulcanize the latex rubber deposited thereon so as to reduce the size of the interstices between the threads of the fabric to a point "at which the passage of water through said interstices is prevented bu the passage of air still permitted.

2. A process, as claimed in claim 1, wherein the heat and mechanicalpressure are applied to the latex-coated woven or knitted textile material in a plurality of stages.'- i

3. A process for the'production from a woven or knitted textile material which is permeable both to air and water of a textile product which,

is impermeable to water but which remains permeable to air, which process comprises first applying a vulcanizable rubber v.latex to the said textile material in amount small enough to permit the passage of water through the interstices ofthe treated textile material, then drying the latex-treated textile material, and thereafter applying mechanical pressure and heat to the faces of the treated textile material to permanently flatten and laterally spread, and at-least partially vulcanize the latex rubber deposited thereon so as to reduce the size of the interstices between the threads of the fabric to a desired size, such that the passage of water through said interstices is prevented, but the passage of air still permitted.

4. A waterproof. air-permeable textile fabric, the threads whereof ,are coated by vulcanized latex rubber, which is, flattened and spread to such an extent that the interstices between the threads are small enough to prevent the passage of water, but large enough to permitthe passage of air therethrough, the fabric being substantially identical with that produced by the process set-forth in claim 1. I

FERNAND FREDERIC SCHWARTZ.

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