US2121717A - Method of coating fabrics and product thereof - Google Patents

Description

Patented June 21, 1938 UNITED STATES PATENT OFFIQE METHOD OF COATING FABRICS AND PROD- UCT THEREOF No Drawing. Application May 11, 1935, Serial No. 20,983

1 Claim.

My invention relates to coating with latex, and especially to latex coated fabrics and to methods of coating the same.

When latex colloid is used to coat fabrics and fibers, the materials to be coated are readily wet by the water or other low viscosity constituents of the colloid. Commonly some of the rubber particles are carried into the sub-surface portions of the fibers or fabrics and become embedded '10 therein before they have become coagulated.

This action produces a harsh, stiif'product.

When light weight fabrics are coated in this way the latex may be carried through the fabric and the smoothness and softness of theback surface of the product is destroyed by the latex coagulated thereon. He'retofore, various means have been employed to overcome these defects, such as the use of a high viscosity form of latex colloid, or the use of a colloid which is dispersed in a non-aqueous medium, or a pretreatment of the fabric with a water repellentmaterial, but the defects have not been satisfactorily overcome and the methods are objectionable because of high cost of the coating material, the special methods which are necessary to prepare the coating material, the inconvenience in working the material, and for other reasons.

It is among the objects of my invention to provide methods for applying latex colloid to fabrics and fibers without producing in the product the undesirable characteristics which have been described.

Another object of the invention is to prevent the latex from penetrating through or deeply into the body of a fabric whereby more than a superficial penetration will be avoided.

Still another object of the invention is to pro vide for the manufacture of articles coated with in latex without previously applying a water repellent material to the fibers or fabric which is to be coated.

Other objects will appear from the following description of the invention.

In general, the invention comprises the pretreatment of the fabric or fiber with a latex coagulating substance which is capable of coagulating the latex so rapidly that the latex will have coagulated on the surface, or at most, only into the superficial layers of the material, before penetration which is suificient to materially stiffen the fabrics will have taken place. A water soluble coagulant may desirably be used with an aqueous latex colloid.

As an illustrative embodiment of the invention,

the manufacture of a latex coated silk fabric will be described.

A thin silk fabric 37 wide weighing approximately 0.7 oz. per linear yard was passed through a bath which consisted of a 4% solution by weight of ammonium alum (double sulphate of ammonium and aluminum) in water. The fabric was thoroughly saturated with the solution and the excess liquid was removed by passing the fabric through squeeze rolls and it was then dried. This pre-treated fabric was coated with a normal vulcanized latex colloid. A standard type spreading machine using a comparatively sharp edged doctor knife was used for this purpose. The material was dried and another coating of the latex was applied. Four coats of the latex were applied to this material and the-material was dried after the application of each coat of latex. After drying the last coat, the processing was completed by dusting on sericite mica dust to eliminate any slight tackiness.

The latex colloid used for coating the silk was an aqueous colloid which had not been processed to increase or alter its viscosity. It had the viscosity of the low viscosity colloids commonly known in the art as a normal latex colloid.

The treated fabric was soft and pliable and the treated surface was smooth and soft. Although the silk was an extremely thin material, there was no evidence that the latex had penetrated to the back of the fabric.

The invention is not limited to the treatment of silk. It may be applied with equally satisfactory results to the treatment of animal and vegetable fibers generally, such as cotton, rayon, wool, flax and other animal and vegetable fibers. Woven or fiber-form materials, whether they are dyed or not, are suitable. Any material which is sufficiently soluble in the colloid serum and capable of coagulating rubber particles in the latex colloid and which is not repelled by the serum of the colloid when it is deposited on the dry fibers can be used. For example, organic acids such as formic and acetic, inorganic acids such as-hydrochloric and sulfuric, and soluble salts of the trivalent metals such as ferric chloride, or alums such as the double sulfates of aluminum and the alkalies, and ammonium alum have given good results but other coagulants which are capable of acting on the latex colloid composition to coagulate the latex more rapidly than the fibers can carry the latex of the colloid composition into the sub-surface portions of the fabricated material or fibers can be used. Coagulants which rapidly dissolve in water are desirable for use with aqueous serums. Although an excess of coagulant over that which is suflicient to coagulate the latex may be used an excess is unnecessary. The amount of coagulant remaining in the material before treating with latex may be regulated in accordance with the capacity of the material to hold the coagulant and by varying the concentration of the coagulant solution. In like manner, more or less of the coagulant will be required, depending upon the coagulating power of the coagulant and the quantity of latex which is to be applied in the first coat. Other kinds of porous articles can be coated, colloids which are more or less viscous than normal colloids can be used, and many other modifications of the described conditions may be selected within the scope of the invention. i

It is desirable to thoroughly saturate the article with the aqueous solution of coagulant andthen squeeze out the excess of solution. However, when the material to be treated has a texture which will hold sumcient coagulant on its surface, complete saturation may be dispensed with.

The deleterious effect of coagulants which are apt to injure the fabric upon continued exposure can be avoided by means which are well known to the art. For example, the effect of residual acid may be overcome by treating the finished product with ammonia vapor.

In accordance with the invention, the latex is prevented from penetrating into the sub-surface layers of the article by coagulating the rubber particles before the latex has an opportunity to penetrate far into the pores or fibers. Thus, the

rubber film is superficially deposited and the resulting product is resilient, soft and pliable. The fabric may be coated on one or both sides. Unvulcanized or vulcanized latex colloid which is compounded or un-compounded may be used. In case unvulcanized latex colloid is used and a vulcanized surface rubber is desired, the latex may be vulcanized after the coating is formed.

Since many modifications of the invention may be made and some are suggested by the foregoing description of the invention, it is to be understood that the invention is not limited to the particular embodiments herein described, and that no limitations are intended in the claim except those which are specifically recited or imposed by the prior art.

I claim:

A process for applying an aqueous latex colloid to a fabric and coagulating the colloid on the surface of the fabric without more than superficial penetration of coagulated colloid into the fabric below the surface thereof and with retention of substantially the original flexibility of the fabric being coated, said process comprising saturating the fabric with a solution of latex coagulant capable of coagulating the latex so rapidly that subsequently applied latex coagulates on the surface of the fabric with at most superficial penetration, squeezing out the excess liquid, then drying the fabric, and applying by a spreading operation a coating of said aqueous latex colloid over at least one surface of the dried fabric.

DAVID J. SULLIVAN.