US2294069A - Method of rendering villous surfaces noncrocking - Google Patents

Description

Aug. 25, 1942. c. l.. CAMPBELL METHOD OF RENDERING VILLOUS SURFACES ANNCIIOCKIIXG Filed March 28, 1940 Patented Aug. 25, 1942 METHOD F RENDERING VILLOUS SUBFACES NONCBOCmG cantoni.. campbell, stemma; conn., assigner to The Viscol Company, Stamford, Conn., a corporation of Connecticut Application March 28, 1940, Serial-N0. 326,486

(Cl. Eil- 88) Claims.

.The invention relates to a method of treating flexible materials having a villous or nap surface, and to the product resulting therefrom.

While the invention has particular utility when applied to the finishing of buied or suede leather, it is also applicable to other materials having a napped or hairy surface, such, for example, as articial or mutation suede leather, velvet, plush, or other pile fabrics, or material on which the nap has been raised by special processes or has been produced by the application of separate bres such as cotton orwwbol ock, bufdng dust, etc. to the surface of the material.

In suede leather, as is well known, it is the iiesh side of the skin which is used to produce the finished surface. and this is buffed in a manner to produce a nap or villous surface comprising upstanding ibres. Such surface has a soft, velvety feel, which is one bf the desirable characteristics of this type of leather.

As is also well known in the art, it is frequently necessary to apply suitable pigments to buffed leather in order to level the color and otherwise improve the surface appearance. These pigments may .be applied in either a wet or dry state and usually no binder or other means of causing them to adhere to the leather` is employed. The pigments merely become embedded in the hairs or bres.

Although the excess pigment is brushed od by suitable means, that which remains has a tendency to rub off on and smudge or discolor clothing, upholstery and similar surfaces with which it may come in contact. This well known defect of suede leather is called crocking In cases where the leatherY is dyed but not pigmented, as above mentioned, the bumng dust itself becomes embedded in the nap, and produces objectionable smudging and discoloring of clothing and the like, in the same manner as pigments. f

Dust or particles of nely divided solid matter may also become embedded in other materials having a villous surface, such as artificial leather, pile fabrics and the like, above mentioned.

It is the primary object of the present invention to provide means for locking in this dust or finely divided matter so as to prevent it from escaping` or coming out or rubbing oi, and to do this without disadvantageously aiectlng the character or appearance of the material.

More specically, the object of the invention is to provide means for eliminating crocking,

and to produce a substantially non-cracking suede or bufied leather.

To this end.' the invention contemplates treating the villous surface with a thin illm produced -by applying a suitable liquid coating composition. In carrying out this idea, however, the problem which presents itself is to produce a film or coating of such character that it will not cause the fibres to mat or adhere to each other in groups, o r produce other undesirable results. In the case of suede leather, the important thing is to avoid impairing the velvety feel" of the goods;

The essential characteristics of such a. lm or coating are, therefore, that it must not substantially alter the feel of the villous surface or the flexibility of the material to which it is ap- Y plied; that it must not mat the fibres together; and that it must not disadvantageously alter the color of the goods.

In order to meet the above qualications, l find that the lm or coating material must not Aonly be exceptionally soft and pliable, when set and other villous surfaces such as described, the

ing of relatively smooth surfaces.

material must have such a low degree of adhesiveness that it will not cause the fibres to permanently adhere to each other. 'Ihe film produced by the use of such a non-adhesive coating composition clings to the villous surface solely by virtue of the fact that the irregularly shaped fibres are surrounded by and/or embedded in such lm, and the film is thus mechanically anchored in position.

Suitable coating compositions for the present vpurpose may be prepared from a wide range of materials. They may be prepared from materials heretofore deemed unsuitable for the usual coating compositions, .because of lack of adhe- Example No. 1 Parts by weight Rapeseed nil 100 Sulphur chloride 121/2 Naphtha 90 The sulphur chloride is first mixed with the oil and stirred, and as vulcanization proceeds and the mixture thickens, the naphtha is gradually added. When the reaction is complete, and the naphtha has all been added, a mixture results which should have a viscosity of about 2.2 (measured with an Engler viscosimeter) To two volumes of the above concentrated mixture, I then add a relatively large amount of solvent, amounting preferably to as much as thirty volumes. additional naphtha, but ispreferably a mixture of half naphtha and half carbon tetrachloride, which is less inflammable. The thus diluted liquid is then ready to apply to the suede leather or other villous surface by spraying by means of air pressure,

As another illustration, I may employ a mixture of partially vulcanized oil with drying oils. I may employ the same vulcanized oil as in Example No. 1, or I may use other vulcanizable oils such as cottonseed oil, as f ollows:

Parts by weight cottonseed nil 100 Sulphur Chloride 18 Naphtha 90 This is then mixed with drying oils and other materials. as follows:

Example No. 2

Parts byl weight Partially vulcanized oil solution (as above) 20 China-wood oil 30 Linseed nil 30 Manganese dryer 6% solution' .125 Solvent naphtha 800 The iirst three items, comprising the vulcanized and drying oils, are thoroughly mixed together. the drier (which may be of the linoleate type) is dissolved in the naphtha, and the whole4 mixed together in an enclosed mixer.

The resulting solution is thin enough to be readily sprayed.

Instead of 30 parts each of China-wood oil an linseed oil, 60 parts. of linseed oil may be used.

Similarly, any other suitable drying oil may be employed by slightly varying the proportions of drier and vulcanized oil, as necessary to secure a proper balance.

It will be understood that in this example, the purpose of the vulcanized oil is to prevent the drying oils from forming a hard, adherent lm. The' presence of the vulcanized oil renders the nlm permanently soft and pliable, and relatively non-adhesive.

This may consist entirely of Still another group of substances which may be successfully employed comprise natural rubat the same time, does not result in the production of any appreciable drag. In preparing such a composition, I may use ingredients in the proportions shown below.

Example No. 3

. Pounds 45% V2 sec. nitro-cotton solution.. l5

Plasticized rubber 23 Toluol 640 Ethyl acetate 128 Butyl acetaha 128 Raw rubber, such as that known as pale crepe, is used, and this is'masticated for a much longer period than is customary in rubber compounding, for example, one and one-half hours, in order to reduce the viscosity of the resulting mixture.

After this ultra-mastication, the plasticized rubber is dissolved in a mixture of the three solvents, by agitation in an enclosed mixer. When the rubber is entirely in solution, thus forming a thin rubber cement, the nitro-cotton solution is added and agitation continued to insure thorough mixing. Although V2 sec. cotton is specified in the above example, the exact viscosity of the cellulose derivative may vary over wide limits without materially affecting the results, provided an equivalent amount of dry cellulose derivative is employed in every case. Equally good results may be obtained by using nitro-cotton solutions with viscosities ranging from V2 sec. to 60 sec.

'I'he essential thing in making up this coating composition is to employ liquid mixtures which' are mutual solvents of the nitro-cotton and of the rubber.

` Many other solvents, such as commercial lac- (quer thinners, including amyl acetate, or combinations thereof with other liquids such as alcohol, may be substituted for the solvent mixture specified, provided that the least volatile ingredient is a common solvent of both rubber and the cellulose derivative, and provided also that the alcohol content is sufficiently low so that the rubber will not be thrown out" of solution.

In order to provide additional coverage and to further level the color of the villous surface, it is often desirable to incorporate in the above coating compositions suitable pigments. These may be added in any well known manner, as, for example, by grinding into the solutions the desired quantity of pigment, preferably before unal dilution with the full amount of solvents. No attempt is made to specify the precise amount of pigment that should be added, because this will i depend on particular circumstances and may vary adhesiveness, but the films resulting therefrom must have very slight; mechanical strength. Thus, for instance, the composition set forth in Example No. 1, if applied to a smooth surface as glass or sheet metal, will produce a. film, which, when dried or set, has practically no adhesiveness or mechanical strength. If such a nlm is rubbed with the finger, the material win rou up in noodlesf and rub off, while, if anattempt is made to lift an edge of the nlm, as by means of a knife blade, and strip it from the smooth surface, it will merely come to pieces in small lfragments, not having sufficient strength to hold together. 'I'his characteristic of low adhesiveness and small mechanical strength is also true of the other two examples.

The amount of the liquid coating composition and the purpose for which the :coating is applied.

Even in the Icase of suede leather, the amount of coating material to use depends on the kind of leather, the amount of builing, the amount of dust or pigment embedded in the nap, etc. By way of illustration, it may .be said that the amount of coating material applied to the surface of suede leather, in carrying out the invention, may vary from .3 ounces to 2 ounces per square foot. The proper amount for any particular kind and type of surface being treated can only be determined by experiment.

The amount of liquid employed is usually sumcient to thoroughly wet the material and the liquid penetrates the nap and settles down throughout the mass of the nbres and around the dust or pigment, and when the solvents have evaporate, there remains a Ipermanently soft, pliable nlm, covering and surrounding the nbres of irregular shape, and thus mechanically anchored to the material.

In order that the principle underlying the invention may be more Iclearly understood, refere ence is had to the accompanying drawing, forming rpart of this specification, and in which the figure is a fragmentary transverse section on a greatly enlarged scale,` through the buned side of a piece of suede leather treated in accordance with the invention.

It will be understood that this drawing, which is a highly magnined view, is intended to illustrate more o r less conventionally and diagrammatically .what happens when a piece of buifed or suede leather is pigmented and coated in accordance with the :present invention.

In this drawing, a designates the portion of the main body of the leather adjacent the nesh side, while b designates the fibres constituting the buifed or villous surface. It will be understood that these nbres are, in fact, made up of bundles of smaller nbrils or nlaments, some of which branch from the sides of the main group, as indicated at c, the outer ends of these branches, and also of the main group, being ragged and frayed, due to the cutting and tearing effects of the bufnng operation. In other words, the surface comprising the nbre groups such as b and cis highly irregular.

To this irregular villous buifed surface is applied nnely divided coloring material or pigment. The particles of such pigment are indicated at d. Many of these particles nnd their way down into the spaces and pockets adjacent the roots or bases of the fibre groups, while others become embedded in and cling to the sides or endsof the nbre groups themselves, as indicated atd'.

When the coating material is applied to such e. bunedsurface, as by spraying, some of it covers the nbre groups, enveloping the pig-ment particles clinging thereto, and some of it finds its 5 way down into the crevices andpockets around the base of the nbre groups.

Thus a substantially continuous film is formed surrounding and covering the individual fibre groups and the particles of pigment which cling to or are embedded therein.

The thickness orf this film adjacent the base of the nbre groups is determined .by the amount of coating material which is applied. This material, however, Ibeing extremely nuent and relatively non-adhesive, tends to run-down the nbre groups and collect in the crevices and pockets around the bases thereof, so that the thickness of the nlm e which covers the outer portions of the nbre groups, remains practically constant,

within limits, regardless of the amount of material applied. As indicated in the drawing, the nlm e enclosing the outer portions of the nbre groups, remains relatively thin, whilevthe nlm e surrounding the lower portions of the nbre groups is relatively thicker, and thethickness of this \nlm e is determined |by the amount of coating material which is applied.

In practice, care must be exercised to avoid applying an excessive amount of coating material such as would cause the nlm e to become too thick, and the crevices and spaces between the fibres nlled up to too great an extent. In other words, in order to preserve the velvet feel of the material, it is necessary to refrain from building up the nlm e too high and to maintain the outer portions of the nbre groups separate from each other, and free to move about, and,

owing to the thinness, softness and flexibility of It appears that in order to have a soft fee1,4v

it is not necessarily a requirement that the ends of the fibre groups be bare, but merely that they be free from each other and nexible.

'In case a little too much of the liquid coating composition is applied to the leather, so that there is a tendency for the nap to become matted, thus giving rise to a somewhat harsh feeling,

it is only necessary to brush the leather lightly, after the lsolvent has evaporated. This results in restoring the feel and appearance to the leather surface, which effect is probably due to the fact that the ends of the nbres are broken loose or separated from each other.

In order to roughly illustrate the appearance of buffed leather coated in accordance with the present invention, it may -be said that what happens is somewhat similar to the effect of a light sleet storm on a plot of lawn grass, or in a still more highly magnined concept, the elect of a sleet storm on a. thickvforest of bare trees. The essential difference is,\however, that while, in the sleet storm, the application of additional matelrial continuously increases the thickness of the coating on the twigs and branches, in the present invention the application of additional material appears not to substantially increase the thickness of the coating on the trees and branches,

but the material collects in a layer of greater or less thickness around the bottoms or bases.

While, in the claims, I have, for simplicity, used the term nbres, it will be understood that I mean to include either single nbres or groups of nbres as above explained. l

What I claim is:

1. A new product .comprising buffed leather, in the buffed surface of which nely divided solid material is embedded, said material being covered by a protecting film which surrounds the individual fibres and is thus anchored to the buiedurface, the outer portion of said fibres being substantially free and separate and said nlm being of such 'a soft, flexible, non-adhesive nature that the velvet feel of the leather is not substantially impaired thereby.

2. A new product comprising buied leather having a pigment embedded therein between the fibres thereof, and having a soft, pliable nlm applied Vthereto over said pigment, and surrounding the bres, the outer ends of said fibresremaining substantially free and separate, said nlm being relatively thick at the point where it surrounds the base of the fibres, and relatively thin at the point where it covers the outer ends of said libres. 3. A flexible sheet having a villous surface,

and having a soft, pliable. substantially continuous nlm comprising vulcanized oil surrounding and interlocked with the base of the fibres thereof. the outer ends of said fibres being substantially separate from each other.

4. A flexible sheet having a villous surface, and having a soft, pliable substantially continuous lm of low adhesiveness containing a mixture of vulcanized and drying oils surrounding and interlocked with the base of the ilbres thereof, the outer ends of said fibres being substantially free and un-matted.

5. As a new product, sueded leather having iinely divided solid material embedded in the builed surface thereof, and also having a soft, protecting lm of low adhesiveness and slight mechianical strength enveloping said material .and the individual n bres of the leather, said lm containing a vulcanized oil, and the outer portions of said fibres remaining'substantially free and separate.

6. As a new product, sueded leather having l finely divided solid material embedded in the buied surface thereof, and also having a nonsticky, soft, protecting film enveloping said material and the individual fibres of the leather, said lm comprising a mixture of raw rubber and a cellulose derivative, and the outer ends of said fibres remaining substantially free and separate.

7. A new varticle of manufacture comprising non-crocking suede leather, said leather havin!V -the fibres thereof, the end portions of said fibres being substantially free and separate from each other.

9. The method of locking in finely divided solid matter embedded in the bres of a flexible sheet having a villous surface which comprises spraying onto said sheet a liquid coating material of such low viscosity that it flows along the fibres and collects at the base thereof, over said solid matter, thus forming, when dry, a substantially continuous illm covering said solid matter and surrounding and interlocked with the bases of the iibres, and so limiting the amount of such coating material thus applied that the ends of the fibres are not caused to mat or cling togeher, but remain substantially free and separa e. y

10. The method of rendering suede leather non-crocking which comprises spraying on to the buffed surface thereof, in which finely divided solid matter is embedded, a liquid coatingmaterial of such nature that it penetrates the nap and collects around and at the base of the fibres over the finely divided solid matter embedded therein, thus forming, when dry, a film vcompletely covering said solid matter and enfeel is not substantially impaired.

CLINTON L. CAMPBELL.

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