US1436106A - Process for manufacturing synthetic leather - Google Patents

Description

patented Nov, 21, 1922,

UNHTElD STATES HUBERT W. MORGAN, 01? LAKEWOOD, OHIO.

PROCESS FOR MANUFACTURING SYNTHETIC LEATHER.

No Drawing.

To all whom it may concern. 7

Be it known that I, HUBERT W. MORGAN, a citizen of the United States, and resident of Lakewood, in the county of Cuyahoga and State of Ohio, have invented certain new and useful Improvements in Processes for Manufacturing Synthetic Leather, of which I hereby declare the following to be a full, clear, and exact description, such as will enable others skilled in the art to which it appertains to make and use the same.

The objects of the invention are to provide an improved process or method of producing an elficient and useful material having all the valuable qualities of natural leather, including great tensile strength, softness and flexibility and superior wearing qualities with the added advantage that it is waterproof and all of these qualities are controllable to adapt the material to a large variety of commercial uses.

By means of this process a material is produced having a controllable amount of flexibility and tensile strength which will outwear natural leather and is capable of being employed in the mechanical arts, and for universal use in every situation in which leather or its several substitutes can be employed, and at very much less initial cost for materials and labor.

Further advantages are found in the economical use of scraps cut or trimmed from the improved material which can be retreated and incorporated into sheets of equally good material for further use.

This cannot be accomplished with natural leather or canvas coated or other coated substances of leather.

B means of the process, a homogeneous pro uct is obtained which can be rolled into sheets of any desired thickness and by regulating the uration of time of the different portions of the treatment, the toughness, amount of tensile strength and the softness and flexibility of the product, and the fineness and evenness of texture, can be positively controlled.

The material can also be washed or cleaned and its surface grained, embossed or finished in the same manner as leather, also when colored the entire body of the material is permeatedthroughout with the color, so that the appearance when worn, is

superior to that of leather.

The various steps of the process which in-= elude, physical, chemical, and mechanical Application filed October 30, 1919. Serial No. 334,593.

operations, are hereinafter more fully described 1n their proper order of succession from the collection of the crude material until the product is ready for commercial 6 use.

The materials employed are fibrous materials of any sort such as wood fiber, in a fine conditlon as saw dust or wood flour, old

rags or rope, straw, grass, hemp, jute, etc. 65

ture if the crude materials are previously it shredded to a uniform amount of fineness. This also makes the materials easier to handle.

Before going through the digesting process, all oil and grease are removed from the 8@ material b means of a hot bath in an alkaline solution of caustic soda. This bath when continued will also soften and partially dissolve the fibers, the duration of the period of its use depending upon the as strength of the solution employed. After having received this bath, it is washed to remove the traces of soda, and is then subected to a further digesting process in a ath of weak acetic acid, or combination of to acids or solvents, which has the effectof reducmg some of the fibrous materials to an amorphous cellulose condition and partially digesting others, until the remaining fibrous material will not exceed a predeter- @155 mined percentage of the whole mass, according to the ultimate tensile strength and fineness and quality of the product desired,

and is also commensurate with the amount of toughness, softness and flexibility desired, too

since the softness wouldflseglost if the whole mass was converted into cellulose.

By means of this step, the mass is reduced to a soft lastic condition. The acid treatment is 0 short duration and after the material has arrived at the lastic and doughlike condition, any desired binding maternal, such as lac, or varnish gum, or any kind of gummy material is dissolved in a solvent such as petrols, such as gasoline or ben'zole, and is added in a proportion determined by the bi-sulphide of carbon, or one of the amount at flexibility desired in the finished all did

product, and thoroughly incorporated with the mass by kneading, pressing and rubbing under mechanical pressure in' any sultable device until the binder and mass are completely unified; also any coloring pigment can be introduced at the same time 1n the.

sun, which has the efiect of tempering or setting the mass, and evaporating the solvents from the surface, and leaving 1t in acondition to be mechanically treated to produce the flexible sheets adapted for commercial use.

This is accom lished by passing the plastic material t rough a succession of moderately heated rolls or through rolls in a chamber in a perfectly dry or artificially dried atmosphere, the object being to flatten and elongate the mass andv reduce it to the form of sheets, which can be cut into sizes suitable for commercial use, and also to submit it to a further kneading pressure, which efiects a further amalgamation and unification of the mass, which produces an improved fineness and evenness of texture throughout, the physical action of the rollone so idifying the mass .in which the fibrous condition gradually disa pears.

If this treatment by ro ing pressure is carried too far, the material will harden and lose flexibility, and the period of rolling is determined by the thickness of the material desired, and the quality of the finished product.

After rolling, and before curing, any dem red finish of surface can be given to the sheets, such as graining, embossing or other finish.

The final stage comprises exposing the sheets in a heated room to a current of air until they are perfectly cured; the time of the exposure depending upon the amount of cellulose in the structure and the thickness of the material.

The strength of the material increases constantly during the curing process and for months afterwards, and the quality will not deteriorate when the sheets have been manufactured, and the manufactured articles have been put into use, or when the sheets are stereo and the materials standing idle because there is no animal matter in the composition, thus making it superior in durability to leather or imitations thereof.

e process is also of short duration and is muc less expensive in time and labor than the innumerable processes to which leather must be subjected 1n soaking the skins,

naeaiea tanning, tawing, softening, finishing and-ts treating for its several uses.

Having described the invention, what I claim as new and desire to secure by Let.- ter-Patent is:

1. The hereinbe'fore described process of W manufacturin a leatherlike material consisting in 00 ecti'ng a mass, of fibrousmaterial, treating the same to "a bath of softening solution, and next to a'bath of acetic acid, permitting. the same to partially set, and then mechanically manipulating to compress and solidify the same, and then curmg the mass.

2. The hereinbefore described process of reducing a. mass of fibers to apartially so amorphous cellulose and plastic condition, said mass containing unre uced fibers, consisting in, treating said mass of fibers 1n an alkaline solution to soften and partially dissolve the same, next treating the mass in a bath of weak acetic acid for a limited period of time, determined by the amount of softness, tenacity and fineness of substance of the product, desired, and finally curing the same.

3. The hereinbeforedescribed process of manfacturing a flexible product having the characteristics of leather, consisting in, first, reducing the mass of fibers to an amorphous cellulose and plastic body, having partially dissolved fibres therein, by first treating the fibers in a bath of caustic solution to remove all oil or ease therefrom, and to soften and partiahlg dissolve the same, next removing the caustic solution therefrom, and next treating the fibers in a bath of week sylvic acid until a proportion of the fibers are reduced to amorphous cellulose, the proortiorrv of unreduced fibers remaining bein determined by the softness, flexibility an fineness of quality desired in the product and finally curing the same.

4. A rocess for manufacturing a leather materia including, first, providing a mass of previously softened fibrous material, immersing the mass in weak acetic acid until a predetermined percentage of the fibrous material has been converted into an amorphous body thus forming a plastic, doughlike mass, incorporating a binder therein, allowing the mass to partially set and mechanically compressing and kneading the mass to flatten and solidify thesame to give fineness and evenness of texture thereto and finall curin the same by exposing it to 120 circu ation 0 air in a heated room.

In testimony whereof, I hereunto set my hand this 13th day of October, 1919.

HUBERT W. MORGAN.