US2172028A - Production of leatherlike surfaces - Google Patents

Description

UR 291729028 SR Patented Septi5, 19 39 aearcn H0885 PRODUCTION OF LEATHERLIKE SURFACES Raymond C. McQuiston, West Newton, and Henry C. Hopewell, Newton, Mass.

No Drawing. Application August 30, 1935, Se-

rial No. 38,492.

13 Claims.

This invention relates to the production of leather-like surfaces, more particularly to the manufacture of simulated grain leather.

Heretofore it has been proposed to manufacture 5 both artificial leather and what is known in the trade as artificial suede".

The artificial leathers which have been produced may generally be considered as comprising a cellulosic or ligno-cellulosic base, such for example as alpha cellulose or kraft paper stock,

15 an entirely different character.

tion, dusting on a cotton fiock. While by preliminarily dyeing the flock the color of leather may be simulated, the resultant surface does not in any other respect resemble leather.

It has further been proposed to produce a 5 leather suede by applying ground leather to a rubber and a pyroxylin layer attached to the fabric. Such products, however, have never been commercially successful due largely to the fact that no effective adhesion or anchorage of the 30 leather flock to the adhesive could be secured.

Such prior suggestions likewise related solely to the manufacture of a true suede, i. e. a product having a definite or decided nap surface.

The present invention in one aspect relates to 35 the development of a novel compounded leather having the grain surface characteristics of true leather. In another aspect the invention pertains to the production of new types of compounds which are employable to saturate animal,

40 mineral, vegetable or cellulosic fibers and to anchor these tenaciously to a base material such as a rubber, cellulose ester or resin coated fibrous material. The invention equally may be considered as a novel method of combining discrete 45 leather fibers to produce a continuous surface or sheet of fibrous matrix containing large amounts of leather and presenting the characteristic properties of true leather, such as pliability, permeability to air (breathing) and the like. The in- 50 vention similarly may be considered as a. novel method of treating fibers, such as leather, which are incompatible with binders such as rubber to increase the bonding or anchorage efiect between the leather or other fibers and such binders.

We have found as a result of considerable ex- Renewed January 20, 1939 perimentation in this field that fibrous material, such as ground leather, may be bonded together and/or to adhesive surfaces to produce relatively massive articles or relatively thin and tenuous surfaces which present all of the inherent characteristics of true leather. These results are achieved, as will appear more fully hereinafter, by treating the leather, or other fibrous starting material, with special solutions which are characterized by a mutual isotonicity and compatability not only with the chemical components of the fibro-matrix, such as collagens of the leather fiber, but also with typical anchorages. Hence the leather may be treated in loose disaggregated form to produce relatively thick or massive articles or may be processed in the form of a surface layer which is preliminarily adhered to a suitable bonding surface, such as rubber.

An object of the present invention therefore is to produce a novel type of compounded leather.

Another object is to produce improved bonding agents for leather and other fibrous material.

A further object is to produce an improved grain surfaced compounded leather.

Another object of the invention is to produce a novel fibro-chemical matrix.

A still further object is to provide a novel method of treating suede-like surfaces of fibrous materials, such as leather, cotton, cork and wool fiock and the like.

Yet another object is to devise an improved method of treating disaggregated or ground leather to produce new and improved products therefrom.

An additional object is to produce a novel potentially tannable composition.

Yet a further object is to provide a method for increasing the tenacity of the bond between an anchoring surface and fibers.

With these and other equally important objects in view, the invention comprehends the concept of coating, saturating or impregnating fibrous materials, such as leather fibers or cellulose fibers, with special solutions and after impregnation treating with other components to convert the impregnant into another form, by reason of which the fibers are mutually bonded and/or bonded to a suitable, backing.

In one preferred method the novel process is employed for the production of a fabric base which has an adhered layer or surface of the improved compounded leather. It will readily be appreciated, however, that from a consideration of the physical and physio-chemical factors involved the principles of the present improvement may be embodied in other and specifically different methods utilizing fibers other than leather to produce analogous and improved results.

As intimated above, it has been proposed heretofore to apply a coating of rubber on a fabric base and while the rubber is temporarily or evanescently softened to deposit thereon a layer or surface of leather. Such methods do not in fact produce a good commercial product. The adhesion between the individual leather fibers and the rubber is so poor that the bond may be broken and the fibers removed by simply rubbing or slightly abrading the surface. In such prior products the fibers were merely embedded to a slight degree in a substance (rubber or pyroxylin) which was substantially incompatible with the leather, that is to say the adhesive substance did not to any material degree penetrate into the surface of the leather fibers.

According to the present process, on the other hand, the fibers constituting the leather surface are largely saturated with a solution which is compatible with the adhesive layer. In point of fact in the improved method the rubber or other bonding agents, as such, is carried into the interior of the fibers, thus insuring a so-to-speak continuous phase of the bonding agent through,

the bonded fiber in sharp contradistinction to the prior practice where a definite or sharp interface obtained between the two heterogeneous components, i. e. the adhesive layer and the fiber.

Again, in the present process the preferred impregnant for the fiber is a proteolytic material which not only is compatible with the leather or other fibers but also has the property of dispersing the collagens of the leather, thus insuring a homogeneous and complete dissemination through and between the fiber. It will be observed, therefore, that these characteristics of the impregnant, i. e. the compatibility with the adhesive on the one hand and the fiber itself on the other, present the ideal conditions for tenaciously adhering the two components into matrices of predetermined characteristics.

Likewise the impregnant possesses another property which renders it peculiarly efficacious for the intended use. As will appear more fully, the preferred proteolytic material used for the material is potentially coagulable or tannable- Hence, if the leather fibers are thoroughly saturated with a material which is compatible with rubber and especially (as in the preferred method) if it itself contains some rubber uniformly dispersed through the fiber, then a true autogenous bond between the treated leather and the rubber layer is insured. When, in addition, the impregnant is of such a character, as here, that it may be tanned to produce a coagulated protein which is substantially homologous with the chemical constituents of the leather fiber, a true homogeneous leather fiber is produced. This is in striking contrast to older processes in which leather fibers were adhered along the heterogeneous interface of incompatible rubber.

With the concept as expressed above in view, it will be appreciated that a number of specifically different impregnating compositions and coagulating solutions are available. It will also be appreciated that in the impregnating and/or finishing solutions adjuvants may be incorporated to accelerate or otherwise improve the saturating, ageing, curing, polymerizing and/or finishing process or advantageously to modify the character of the final product.

As will have been appreciated the desiderata to be attained are thorough saturation of the fibers with impregnating solutions of the character described and reasonably high concentration of the essential constituents of such solutions. While it is possible to achieve improved results by using a single saturating solution and a single finishing treatment, it is found that the best results are secured by subjecting the material to a plurality of sequential treatments with compositions of the type referred to, which compositions are mutually isotonic but in which the relative percentages of the several ingredients are varied. In this manner the matrix-giving concentration of the effective ingredients may be built up and at the same time optimum saturation secured. Thus, for example, the first saturating solution may be so compounded as to achieve rapid and thorough impregnation and subsequent solutions of the same general character utilized to sequentially impregnate the fibers and interstitial spaces and build up the desired matrix concentration continuous with the basic anchoring surface.

To enable a more ready comprehension of the underlying principles of the invention a process for producing a leather surfaced fabric will be described. The preliminary operation involves the application of a rubber surface to any suitable type of fabric material and the subsequent uniform deposition of ground leather or a mixture of ground leather and cellulose fibers to the rubber layer. The fabric so treated is subjected to suitable conditions to cure the rubber and bond the leather fibers to the adhesive layer.

Thus in a typical run a layer of plastic rubber may be applied to a roll of fabric of the desired character by means of the usual machine in which the rubber is uniformly spread over the fabric by means of a doctor blade or equivalent mechanism. Subsequently there may then be applied to the first rubber coat a sheet or layer of calender rubber. Then such layer may be temporarily softened or plasticized by means of suitable rubber solvents, or preferably, there is then applied a separate layer of a rubber cement of the proper viscosity. The fabric with the thus produced plastic rubber surface is then treated in any suitable type of suede or fiock machine and a fine coat of the leather fibers (either alone or in admixture with other fibers) is then applied. If

desired, before the deposition of the ground.

leather, a coat comprising a mixture of rubber cement and ground leather or other fibrous materials may be applied to the calender coat of rubber and the leather fibers subsequently deposited upon this.

After building up the lamelli of the fabric layer, with one or more coats of rubber or rubber in ad'- mixture with fibers, and the final coat of leather, the sheet may be subjected to any suitable degree or character of mechanical pressure to physically embed the leather fibers in the rubber coat and/or to impart any desired surface effect to the leather coat. The thus treated material may then be cured in the usual manner. The material so treated comprises a surface layer of leather either uncompressed or compressed to any desired degree and bonded or adhered to the intermediate rubber layer. The product in this condition'is not of the desired permanent character for, as noted, the leather fibers may be removed from the anchorage by mild abrasion.

As noted above, when it is desired to producean embossed surface the leather coated fabric may be subjected to the pressure of a roller, plate or H7. (JUAIINU; PHUUtSStS ANU MISCELLANEOUS PRODUCTS.

other means to produce the desired surface effect. Thereupon the material is submitted to the action of the special compositions mentioned whereby the improved characteristics previously described are imparted to it.

For factory operations it is desirable to provide certain stock solutions and utilize these to compound the treating or base solutions as required. For this purpose therefore the following stocksolutions are utilized:

Stock solution #1 Parts Blood albumen 1 Cold water 12 Stock solution #2 Parts Animal glue or gelatine 1 Glycerine 2 Mixture of linseed, tung or corn oil and sulphonated castor oil A Naphtha or other rubber solvent A,

Water 16 Stock solution #3 Rubber latex (35 to 40% rubber) Stock solution #4 sulphonated castor oil Stock solution #2 may be made up by soaking the glue or gelatine in cold water and dissolving by known methods. The other ingredients are added and agitated until a homogeneous dispersion is secured. a

The first saturating or impregnating solution is prepared in any desired amount from the foregoing stock solutions according to the following formula.

Base solution #1:

50 parts by volume of stock solution #1 50 parts by volume of stock solution #2 10 parts by volume of stock solution #3 5 parts by volume of stock solution #4 Base solution #1 may be made up by agitating the several solutions in a mixing vessel and preferably at slightly elevated temperature.

Base solution #2:

50 parts by volume of stock solution #1 50 parts by volume of stock solution #2 4 parts by volume of stock solution #4 Base solution #2 may similarly be made up simply by agitating the respective ingredients under conditions which will insure their dissemination and admixture.

The first base solution may be applied to the leather coated fabric in any suitable manner. A method which has been employed with pleasing results is to apply the stock solution in much the same manner as the rubber cement, by spreading uniformly over the exposed leather surface by means of the doctor blade or other equivalent mechanism. It Will be understood, however, that the treating solution may be applied in any other desired manner, as by dipping, spraying and the like. After the material has been treated with the base solution #1 it is allowed to dry or cure.

It will be appreciated that the base solution 1 contains in addition to the tannable proteins, a predetermined percentage of rubber and rubber solvents, and saturation or penetration accelerators of the character of sulphonated castor oil, and plasticizing or gel-extending agents such as glycerin. This solution is so designed or de- DBHTCH boom vised as to insure optimum penetration. Such solution, being of the proper viscosity and surface tension, penetrates into and saturates the leather fibers. Preferably the penetrant solutions, i. e. base solutions #1 and #2, are adjusted to a pH of between 5.0 and 6.8, a pH of 6.2 being preferred. The base solution #2 is isotonic with the semi-dried components of base solution #1 and serves to carry additional proteolytic material into and between the fibers. By treatment with base solution #1 therefore the leather fibers are saturated with a potentially tannable solution which also contains dispersed rubber and the solution itself is compatible with the rubber anchorage. Subsequent application of solution #2 carries into and between the fibers additional amounts of the collagen simulating substances.

If desired, other agents, such as predetermined percentages of Irish moss, carbohydrates, lichens, cellulose esters and ethers, hygroscopic salts, vulcanizing agents, accelerators, pigments, dispersed resins and the like may be incorporated in the impregnating solution.

After the leather coated fabric has been treated with base solution #1 and this solution has partly dried, the fabric is then treated with base solution #2. This similarly may be applied by means of spreading the solution with the typical knife or doctor blade and after application of the solu tion the material is again allowed to dry. The treatment with the second solution serves to further impregnate or penetrate the individual fibers and to fill up the interstitial spaces between the fibers. In some circumstances, for example when the leather coated material is subjected to a relatively low degree of pressure during fabrication, it is advantageous to utilize an additional saturating solution. Such solution may, for example, be similar to base solution #1 or base solution #2, or a combination of the two.

After the material has thus been thoroughly impregnated and saturated with the impregnating solutions, it is then treated with finishing compounds. In the preferred process the material is subjected to two finishing treatments. The first comprises a saturation with stock solution #2, that is to say with a solution comprising 1 part of glue, 2 parts of glycerin, part of a mixture of drying oils and sulphonated castor oil, A part of rubber solvent and 16 parts of water. This solution, being compatible or isotonic with the dried constituents of the preliminary impregnating solutions, diffuses through and becomes an integral part of the-proteo-fibro-matrix and builds up or increases the concentration of the tannable protein and softening or plasticizing agents. After treatment with this solution the material is then subjected to the final finishing treatment.

Such final finishing solution may be formulated as follows:

100 parts by volume of stock solution *1 2 parts by volume of sulphonated castor oil (or equivalent material, such as sulphonated cod oil) 3 1 parts of formalin (40% formaldehyde) Due to the low viscosity, penetrability and capallarity of this solution the liquid is readily absorbed into the previously formed matrix and uniformly disperses therethrough the included tanning agent, namely the formaldehyde. After impregnation or saturation with the final finishing solution, as will be appreciated, the proteclytic components of the saturant are tanned or coagulated in, on and around the leather fibers. As pointed out hereinbefore, the inclusion of rubber latex and rubber solvents, in finely dispersed condition, in the first saturating bath insures a continuous or autogenous bond between the leather fibers and the separate rubber anchorage or layer. As a result of the proteolytic and tanning treatment the coated material then contains substances which, from a chemical and physical standpoint, closely simulate the chemical structure of true leather and functions to bind the leather fibers to each other and to the rubber anchorage in a tenacious yet flexible and homogeneous mass.

It will be understood that a number of products of different physical, optical and chromatic characteristics may be produced by the present process. Thus where a. lustrous, colored and/or highly water resistant top or finish is desired, anyone of a number of known aqueous or anhydrous compositions, such as lacquers, dispersed resins and/or waxes, varnishes and so forth may be employed.

It will be understood that the actual impregnation of the leather, cellulose or other base material, may be eifected by employing a number of specifically difierent apparatus. The equipment employed naturally will depend toa large extent upon the physical state of the fiber which is to be treated. Depending upon the characteristics of the fiber base employed and the demands of the final product, impregnation and fixation may be carried out either intermittently or continuously. Because of the effectiveness of the penetration and the completeness of the coagulation or gelatinization caused by the fixing solutions, a very wide permissive flexibility of manipulative technique is available.

While the foregoing description considers the use of rubber as a basic anchorage, it will be understood that other bonding compositions may be employed, as for example pyroxylin, resins, drying oils and the like. Depending upon the anchorage utilized, cellulose xanthate, ethyl cellulose, shellac, linseed oil and/or their solvents may be dispersed in Base Solution #1 in substantially the same proportions as recommended for rubber latex and the rubber solvent. It is also possible to employ as a basic anchorage aqueous adhesive agents of the character of dextrine or casein, in wh ch case all anhydrous solvents, rubber, cellulose ester, resins and so forth may be eliminated from Base Solution #1.

While improved grained leather surface products may be produced by the process described, it is particularly to be observed that a salient feature of the invention is the special combination of the aqueous matrix-forming material and its reaction on or association. with fibers. It will thus be observed that what has been said of the advantageous modification of the leather and other fibers by these solutions, when such fibers are in sheet form, will apply equally when they are in relatively massive form. This is to say that the invention is not limited to the treatment of leather suede surfaces but may be employed with improved results to produce relatively massive fiber base articles. Thus loose disaggregate leather fibers, in admixture to any desired degree with cellulose or other fibers, such as cotton linters, may be treated with the impregnating solutions to thoroughly saturate the fibers. Such saturated fibers may be subjected to any desired degree of mechanical pressure to produce a formed article, and may then be treated with the fixing solutions to insure coagulation. The

resulting product then is true leather bonded with a bonding agent which closely simulates the nonfibrous constitutents of real leather.

It will be understood that a broad feature of the invention comprehends the concept of impregnating fibrous material with lyophobic, isotonic, matrix-forming materials. Thus it is to be clearly understood that other materials may be utilized in lieu of albumen and glue, such as casein, starch, iceland moss and the like.

It will likewise be appreciated that the treatments herein described are available for the treatment of pure or relatively pure cellulosic sheets or coatings. As has been noted hereinbefore, the typical artificial suede now produced comprises a finely ground cotton flock dusted upon a rubber anchorage. Such material presents to some degree the disadvantages of erstwhile artificial leather suedes in that the adhesion or anchorage of the cellulose fibers in the rubber layer is not tenacious. Such artificial suedes have been treated according to the present invention, i. e. by saturating with the saturating baths, followed by subsequent fixing or coagulation with the finishing baths, to produce improved suede products. In these products the cotton, wool or other fiber is not only more firmly anchored to the rubber layer than in prior products, but improved tactile characteristics are imparted to the flocked mass. The products produced according to the present process, when starting with an artificial suede, present the softness of a moleskin in sharp contradistinction to the harshness of typical cotton suede finishes. This improvement is believed to be due, as explained, to the fact that a truly autogenous bond is established between the cellulose fibers and the rubber layer, due to the incorporation of predetermined quantities of rubber directly in the substance of the fiber. The improved tactile characteristics are undoubtedly due to the fact that by the formation of, a matrix there is included in and between the cellulose fibers the simulating constituents of true leather.

It will be apparent also that a number of adjuvants may be included in the saturating and/or fixing solutions to advantageously modify the characteristics of the final product for any particular use. Thus where the use to which the final or ultimate article is to be put so dictates, additional fillers such as natural resins, ground resinoids, pigments, dyestuffs, inorganic powders and the like may be incorporated. Likewise, as will be appreciated by those skilled in the art, the relative percentages of ingredients herein set forth may be varied to conform the final article to any particular requirements. Thus, if it is desired to produce a leather coated article having a relatively high degree of flexibility, the quantity of glycerine and/or the quantity of sulphonated castor oil may be increased Within reasonable ranges. Similarly, if desired, other impregnants either of an oleaginous or non-oleaginous nature, such as graphite, saponin, rosin, starch, soap stone, insoluble soaps and the like may be employed.

It is also clearly to be understood that the invention is by no means limited to the specific compounds mentioned in the formula. As noted, in lieu of albumen, other similarly acting matrix forming material may be utilized. Likewise instead of glycerine, glycol bases may be employed. Manifestly in lieu of sulphonated castor oil other sul- H7. COATING; PROCESSES AND MISCELLANEOUS PRODUCTS.

phonated or saponified water miscible oils, fats and waxes may be used. It will be clear, too, that the percentages of rubber or other bonding agent included in the mix may be varied within relatively wide ranges and that the character of that rubber incorporated in the saturating solution may be varied. Thus, in lieu of natural latex, dispersed solublized rubber is available.

It is understood by this invention that nonfibrous backings may be employed as bases for fiber attachment and the subsequent impregnation thereof. For example continuous sheets of rubber, regenerated cellulose, of themselves, may act in a plastic state of with supplementary binder coatings as carriers of the fibrous matrix hereinbefore described. Further it is clear that the process herein described may apply to one or both surfaces of the backing employed and that a building up of such surfaces is possible to any desired degree.

It will be apparent that the base materials made in accordance with the present invention are susceptible of a wide field of use. The heretofore described surfaced materials may be employed in all of the fields in which real or artificial leathers are now utilized, such for example as upholstery, shoe manufacture, luggage, wearing apparel, books, spinning roll coverings, gaskets and the like. Similarly, as pointed out, the principles of the invention may be utilized to produce relatively thick and stiff articles, such as sole leather, heavy luggage and the like.

Thus it will be appreciated that the process is applicable to true leather, such as ground leather scraps, other animal, vegetable or mineral fibers, mixtures of animal, vegetable and/or mineral fibers, whether such fibers be in the sheet or the massive form, and that such fibers may be adhered through the medium of the novel matrices described to any desired type of fibrous or nonfibrous backing. There the invention is considered to comprehend the concept of the treatment of any type of animal, vegetable or mineral fiber, the characteristics of which are to be improved by the described process.

We claim:

1. A method of producing leather surfaced articles comprising applying a bonding surface to a fibrous base, depositing dry ground leather continuously on the surface to adhere the same thereto, saturating the leather and filling the interstitial spaces between the leather fibers with a solution containing tannable protein materials I and tanning such materials after saturation.

2. A method of producing improved leather like material comprising applying a resilient adhesive coating to a fibrous base, depositing cut fibers on the surface in continuous form to adhere the same thereto, saturating the thus flocked fibers with a matrix forming solution containing tannable protein material such material being characterized by a marked compatibility with the said adhesive surface and a high penetrability for the said flocked fibers and tanning such material after saturation in, on and between said fibers.

3. An article of manufacture comprising any suitable flexible, fibrous base having a bond containing surface, a continuous coating of a mixture of leather and other fibers adhered to the surface, which fibers and surface contain impregnated protein material which is made lyophobic in situ after impregnation.

4. An article of manufacture comprising a f a bric base having a rubber containing surface adlTered to the baseyaiofiti'huous coating of leather fibers adhered to the rubber surface, said fibers, the spaces therebetween and the rubber containing surface containing added tanned protein material and softening agents such protein material being tanned in situ after impregnation thereof in the fibers and said rubber surface.

5. A method of producing leather surfaced articles comprising applying a rubber surface to a fabric base to adhere the surface to the base, depositing dry ground leather on the surface to adhere the leather thereto, saturating the leather and filling the interstices between the fibers with a solution containing tannable protein material and tanning such materials after saturation to form a chemical leather-like matrix autogeneously bonding the fibers and the rubber surface thereto.

6. A method of producing compounded leather surfaced fabrics which comprises applying a layer of resilient adhesive material to a fabric, depositing thereon dry, natural out fibers and after deposition impregnating the fibers and filling the interstitial spaces between the fibers with a protein containing solution which is compatible with the adhesive and then tanning the protein of the solution.

7. As a new article of manufacture a fabric base having an adhered grained surface comprising ground leather which is impregnated with protein material, which protein material is tanned in situ after impregnation in the leather, the tanned protein material also filling up the interstitial spaces between the ground leather fibers.

8. A method of producing improved fiber surfaced articles which comprises applying a layer of plastic rubber to a fibrous base, depositing thereon a uniform coating of finely divided natural fibrous material, curing the rubber to anchor the fibers thereto; then impregnating the fibers with a solution containing tannable protein material, plasticizing agents and dispersed rubber, which solution is compatible with the said layer of plastic rubber drying the material and then further impregnating the fibers and filling the spaces between the fibers with an aqueous solution containing a tanning agent for the tanning material, a waterproofing agent and a solvent for the waterproofing agent.

9. A method of producing improved fibrous surfaced articles which comprises applying a layer of a polymerizable resinous material to a fibrous base, depositing thereon a uniform' coating of finely divided dry, natural fibrous material, polymerizing the said polymerizable material to anchor the fibers thereto; then impregnating the fibers with a solution containing tannable protein material and a substance compatible with the polymerizable material, drying the material and then further impregnating the fibers with an aqueous solution containing a tanning agent for the tanning material, a waterproofing agent and a solvent for the waterproofing agent.

10. A method of producing improved fibroussurfaoed articles which comprises applying a layer of an oxidizable oil to a fabric base, depositing thereon a uniform and continuous coating of finely divided fibrousmaterial, oxidizing the oil to anchor the fibers thereto, then impregnating the fibers and filling the spaces between the fibers with a solution containing tannable protein material and a substance compatible with said polymerizable oil drying the material to form a fibro-chemical matrix and. then further impregnating the fibers with an aqueous solution containing a tanning agent for the tanning material.

11. A method of producing leather surfaced articles comprising applying a bondingosurtace toa fibrous base, depositing dry ground leather uniformly on the surface to adhere the same thereto, saturating the leather, and filling the interstitial spaces between the leather fibers with a solution containing tannable protein material, and which solution is maintained at a pH of between substantially 5.0 and 6.8, and tanning such materials after saturation.

12. A method of producing leather surfaced articles which comprises applying a bonding surface to a fibrous base, depositing dry ground leather uniformly on the surface to adhere the same thereto, saturating the leather and filling the interstitial spaces between the leather fibers with an aqueous solution containing tannable 13. A method of producing leather surfaced articles which comprises applying a resilient ad; hesive coating to a fibrous base, depositing cut fibers uniformly on the coating to adhere the same thereto, saturating the fibers with a matrix forming solution containing tannable protein material, which solution is maintained at a pH of between 5.0 and 6.8, such solution being characterized by a marked compatability with the said adhesive surface and a high penetrability for the said flock fibers; and tanning such material after saturation in, on and between the said fibers.

RAYMOND C. McQUISTON.

HENRY C. HOPEWELL.