US2010871A - Fibrous composition and method of producing the same - Google Patents

Description

Patented Aug. 13, 1935 UNITED STATES PATENT OFFICE FIBROUS COMPOSITION AND METHOD OF PRODUCING THE SAME British corporation No Drawing. I Application January 11, 1934, Serial No. 706,312. In Great Britain January 25, 1933 y 2 Claims. (c1. 154-2) This invention comprises improvements in or relating to the manufacture of compositions containing rubber or similar material.

The object of the invention is to produce improved materials comprising interlocked fibers and rubber.

Various proposals have been made for producing products comprising fibers and rubber. Reference can be made, for instance, to a prior proposal wherein rubber cements are employed. In this earlier proposal cemented integrated fibrous sheets are produced by a method comprising the step of compressing an unwoven sheet of the fiber in the presence of an excess of viscid cement, applied on one face only and advancing one face of the sheet in respect to the other face during such compression, by a shear-like action dependent upon the presence of the viscid cement.

It is pointed out that for the fibrous body which is to be treated, a loose, flimsy web of fiber, preferably cotton, such as ordinary carded cotton batting is employed and it is furthermore pointed out that the carded cotton batting is usually about a quarter of an inch thick in its uncompressed state and is formed by superposing on each other single laps from several carding machines to form a fleece of the desired thickness, this fleece being either left un'sized or lightly dressed on one or both surfaces with size.

The present invention is an improvement on this particular prior proposal in that it is concerned with the use of aqueous dispersions of rubber or the like.

Among prior rubber latex proposals we are aware, for instance, that it has been proposed to produce cellulose caoutchouc products by bringing cellulose into the form of a loose fleece, dipping the said fleece into the milk juice of caoutchouc hydrocarbon bearing plants, pressing off the water, and drying the mass.

It has been suggested that products made by this process can be used as a substitute for cork, leather, linoleum, etc., as insulating material for electro-technical purposes.

We are also aware that it has been proposed to form compound fabrics from layers of fibrous material secured together by anadhesive.

It has also been disclosed to produce reinforced rubber materials using latex as a source of rubber by contacting with acid a jet of latex containing fiber or fabric, allowing thesuperflcially coated body of latex to stand for coagulation throughout, pressing and washing the coagulated article and drying the same.

Disadvantages are, however, -associated with all these prior rubber latex proposals. Either, for instance, the proposed process is difficult to carry into effect or, alternatively or additionally, the product formed is not free from laminations. 5

According to the present invention the method of producing improved materials comprising fibers and rubber comprises coating or treating a carded web or webs of fibers, preferably each web individually, with aqueous dispersions of the kindshereinafter specified and preferably by a spraying operation providing coagulating means for the aqueous dispersions aforesaid on the two surfaces of a, single web, if a single web only is employed, or on the two outermost surfaces formed by a number of superimposed webs and consolidating the web or superposed webs, as the case may be, by the application of pressure.

In order to prevent the materials formed showing signs of laminations, it is desirable that the aqueous dispersions aforesaid should be such as to coagulate well under the combined effect of pressure and drying action of the carded fibrous material.

The main difficulty to be overcome is to prevent sticking of the moist fibers of the carded web or webs to the surfaces between which the single web, or number of superimposed webs, is consolidated. This difficulty is overcome according to the present invention, by coagulating the layers of aqueous dispersions aforesaid on the two surfaces of a single web, if a single web only is employed, or on the two outermost surfaces formed by a number of superimposed webs. Coagulation can be brought about, for instance, by .35 the use of any stronglycoagulating means, e. g., of a 5% aqueous acetic acid or 10% magnesium sulphate solution. This acid can, for example,

be wiped over any faced sheeting material between which the web or webs are consolidated. This treatment ensures a thin coagulated layerat the surface which thus leads to the production of materials of good appearance and clean removal without sticking.

It is desirable that the aqueous dispersions be applied normally to thesurface of a web. For. example, where a web is, for instance, supported .on a drum and sprayed with the aforesaid dispersions, this desideratum can be obtained by directing the impinging spray along'a radius of the drum. If this precaution is not observed, the force of the spray tends to distort and spread the fibers of the web, particularly if the lattenis of light weight.

It has been found in certain cases desirable to employ aqueous dispersions of rubber or the like capable of yielding vulcanized products of small extensibility, otherwise the final material produced is too stretchy and the two phase structure of fibers and rubber or the like too pronounced,

t is also desirable .in working according to the present invention that the fibers employed should be substantially in the dry condition.

Examples of suitable fibers are those which are usually obtainable in the carded condition, the most usual of these being cotton and wool.

The emulsions or dispersions of rubber or the like comprise those consisting of rubber, guttapercha, balata or similar vegetable resins occurring naturally or artificially obtained. Such artificial aqueous dispersions may include those of coagulated rubber, vulcanized rubber, synthetic rubber, waste or reclaim. All of these materials, or mixtures thereof, are herein designated as rubher material. If desired, any of the above mentioned dispersions may be used alone or in admixture with one another.

Any of the aforesaid dispersions may contain the usual known compounding and vulcanizing ingredients and/or may be in the first instance in concentrated form.

Concentrates such as are obtained in Patent 1,846,164, Feb. 23, 1932, or in British Patent 219,635 to which may be added any one or more of the usual known compounding ingredients may also be employed.

The material produced according to the present invention can be subsequently given, for instance, in known manner a suede finish by spraying the material, for example, with waste wool or, may be embossed in the uncured condition in known manner.

It isalso possible to provide attractive surface markings by employing a patterned, for example, leather backing in place of smooth faced sheetmg. l

The following example illustrates how the method of the present invention can be effected- Example A piece of artificial leather of six ply can be made on a small scale as follows:

Faced sheeting is laid on a drum or traveling belt and wiped over with a 5% acetic acid solution.

A length of carded cotton web of suitable weight e. g., 500-600 grains per linear yard 42 inches wide is sprayed on one side with a rubber latex mixing of 40% total solids, alkalinity 0.25:, and of the following composition:

Parts by weight Rubber (in the form of latex) 100 sulphur 3 Zinc oxide 5 Accelerator 0.75 Lamp black 15.0

made by adding the compounding ingredients as aqueous dispersion thereof to a rubber laweb is applied with the sprayed side downward to the treated faced sheeting. The upper surface of this web is then sprayed with the latex mixing. A second length or" web is laid on this sprayed surface and the top layer of this new web is now sprayed with latex mixing. Four more cotton webs are successively superimposed and treated in .a similar manner.

A length of faced sheeting treated with 5% acetic acid solution is then applied to the upper surface of the finally sprayed web layer.

The composite material is now passed once slowly between rubber rollers set for light compression. The faced sheetings are then stripped ofi and the composite material is again passed between the rubber rollers which are now set for high compression. The compressed material thus produced is dried and vulcanized.

What we claim is- 1. A method of producing materials comprising fibers and rubber which comprises impregnating a carded web of fibers with aqueous dispersions of rubber material without coagulating said dispersion, superficially contacting the outer surfaces of said web with a coagulating agent to prevent said outer surfaces from sticking to press ing rolls and thereafter consolidating said webs by the application of pressure.