AU595435B2 - Leather powder, process for producing the same, leather-resin composition containing the leather powder, and process for producing paint containing the leather powder - Google Patents

Description

To: THE COMMISSIONER OF PATENTS (a member of the firm of DAVIES COLLISON for and on behalf of the Applicant).

Davies.& Collison, Melbourne and Canberra.

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0 "00 COMMONWEALTH OF AUSTRALIA PATENT ACT 1952 COMPLETE SPECIFICATION

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FOR OFFICE USE CLASS INT. CLASS Application Number: Lodged: Complete Specification Lodged: Accepted: Published: Priority: 595435 This document contains the amendments made under Section 49 and is correct for printing.

Related Art-: a 0 NAME OF APPLICANT: IDEMITSU PETROCHEMICAL CO., LTD.

ADDRESS OF APPLICANT: 1-1 Marunouchi 3-chome, Chiyoda-ku, Tokyo, Japan.

0* 4 NAME(S) OF INVENTOR(S) Sadao NISHIBORI ADDRESS FOR SERVICE: DAVIES COLLISON, Patent Attorneys 1 Little Collins Street, Melbourne, 3000.

COMPLETE SPECIFICATION FOR THE INVENTION ENTITLED: "LEATHER POWDER, PROCESS FOR PRODUCING THE SAME, LEATHER-RESIN COMPOSITION CONTAINING THE LEATHER POWDER, AND PROCESS FOR PRODUCING PAINT CONTAINING THE LEATHER POWDER" The following statement is a including the best method of full description of this invention, performing it known to us -1- Insert pilce and date or signature. Declared at Tokyo, Japan this 24th day of February, 1988 Slgnature of decllarntt() (no aittlion required) Note- In .itial all I le.tions. Note. Intit alt altetans, DAVlliS COLLISON, MELBOURNE and CANBERRA.

1A BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to an improved leather powder and a process for producing the same, suitable for use for blending with a synthetic resin to form molded articles, and for other various uses as a blend with a synthetic resin or with a paint.

Also, the present invention relates to a leatherresin composition containing the leather powder and to a a.

Sprocess for producing a paint containing the leather powder.

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0 All vertebrates, including humans, have skin containing collagen, that is, a fibrous protein. Collagen a protein have a very complex structure and is insoluble in water. The present invention further relates to a method f of providing articles superior to natural leathers by pulverizing the collagen fibers into fine powder and blending a resin thereto.

According to the present invention, there is provided an artificial leather that is a material having the desirable qualities of natural leather, such as good 2 feel, softness, good texture, resistance to static electricity, and water absorption. Furthermore, the synthetic leather of the present invention is superior to natural leather in that it does not have the disadvantages of natural leather such as the need for constant care or susceptibility to mold, fading, and dirt. The reconstituted leather looks and feels better the longer it *S is used. Unlike the natural leather, it does not age so quickly.

00 Description of Prior Art 6000 0Natural leathers have been utilized for clothes and other articles from of old. They stand long use and 0.

are supple and tough as well as attractive in appearance.

Unfortunately, natural leathers are limited in supply and, 0* .5 because of troublesome tanning processes, become quite expensive when used in manufacture of articles such as clothes, accessories, or the like. Further, because of different shapes and sizes of the original animals, they have disadvantages in that a special skill is needed to cut and make them into clothes, etc. and in that cutting scraps and waste are inevitable.

In recent years, various artificial and synthetic leathers have been developed as a substitute for natural leather. One typical example is a synthetic leather 3 consisting of a substrate of woven or knitted fabric and a sponge leather layer made of a foamed plastics such as foamed polyvinylchloride, polyamide, polyurethane, or the like, the surface of the sponge leather layer being treated with a modified polyamide, polyurethane, polyacrylic acid derivative, or the like.

Another example is an artifi.cial leather having a porous structure and consisting of three-dimensionally entangled fiber member made of special fibers, such as lotus-root-like hollow fibers, bundle fibers of very fine fibers, or the like and a binder mainly composed of an elastomer (polyurethane) and the like.

These synthetic or artificial leathers have characteristics very similar to those of natural leathers

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and have excellent heat insulating property and yet have excellent air-permeability, moisture-permeability, and water repellency. However, water absorption in these artificial leathers or synthetic leathers is limited to the i absorption caused by capillarity, and water absorption due to swelling of tissues does not occur in them. While the air-permeability is controlled in natural leathers as the porosity in the tissues is adjusted by the swelling of the tissues, synthetic leathers and artificial leathers do not have such a function.

In the past, scrap leather has been discarded as IA I

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4 having no available use. Scrap leathers are too small in size to be used for manufacture of leather articles or the like. Some attempts have been made to produce leather-like articles by pulverizing leathers into a fine powder and mixing the powder with a resin. Although the conventional leather-like articles wherein leather powder is mixed into a resin have water and moisture absorbing properties, they have undesirable properties because the grains of the ooo leather powder are liable to tangle or lump together

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***causing an uneven distribution in the resin.

Development of an appropriate method of molding 0 natural leather powder together with synthetic resin will produce a lot of advantages. First of all, the presence of natural leather in the molded articles should improve water and moisture absorbing functions due to swelling, and *"**molded articles not having clinging touch but being agreeable to the touch can be provided.

~Secondly, the presence of natural leather powder in the molded articles should provide suppleness and toughness which cannot be provided by other resin molding.

Thirdly, the presence of natural leather powder should reduce the charging of static electricity resulting in exemption from discharge of static electricity and discomfort caused thereby. Also agglutination of dusts caused by charging of static electricity should be reduced.

1 Furthermore, the heat insulating property of the molded articles containing leather powder should be extremely improved.

Investigation of the method of producing a leather powder to be mixed into resins discovered a difficulty in pulverization of leathers that longer fibers sometimes become tangled depending on the type of leather (whether rawhide of a pig or cow; a particular portion of a rawhide, etc. or properties such as whether the rawhide is of a young animal or of an adult; or the type of tanning or storage conditions under which the rawhides to be treated were placed). Furthermore, such a problem occurred frequently in going from a pilot plant to actual *production.

.9 (In the present invention, the expression "tanned leather" means a substance obtained by tanning a rawhide with tannin, chrome, etc., the word "rawhide" means a rawhide which has not been tanned.) Also it was found that due to forced drying and impact shearing, grains of the leather powder got entangled and took on an appearance of unraveled cotton during storage. The leather powder eventually flocculated making it difficult to mix with synthetic resin. Such a leather powder therefore cannot invest molded articles with properties characteristic in leather and further

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6 deteriorates the desirable characteristics of the molded resin itself.

The presence of flocculated leather powder further led to defectively high increases in resistance in the mixing cylinders or dyes used for extrusion or injection molding causing wear of the cylinder inner wall or damage to the dyes or molds. When extrusion resistance or injection resistance was high, it was necessary to use larger molding machines and the molded products deformed due to shrinkage, etc.

Although the problem of fluidity might have been minimal in molding with a calendar roll, flocculated leather powder in the synthetic resin would often agglomerate or cake, and the product would have an uneven surface. The caked leather powder would also cause cuts or abrasions in the surface of the resin material.

When mixed with a paint, the flocculates of the leather powder maldistribute in the coating layer causing bumps or scars in the coated surface. Additionally, the paint, when used in a spray gun, tended to clog the nozzle of the gun.

Other problems occurred when a film of less than 0.1 mm thickness was to be produced. The flocculated leather powder cause bumps in the film and weakened cirtain are as which eventually led to tearing of the film.

7 Further, in the prior art method, problems of uneven grain size distribution and of longer fibers in pulverizing cow hides because of their tough collagen fiber, with pig skin, on the other hand, the large oil/fat content in the pig hide hampered the efficiency of pulverization.

SUMMARY OF THE INVENTION In accordance with a first aspect of the invention there is provided a process for producing a granular non-flocculating resin-compatible powder having o an apparent specific gravity of 0.38 to 0.8 g/cc from a tanned animal leather, which comprises the steps of: 15 providing a tanned leather cut into chips and/or strips; steam-heating the chips and/or strips to substantially retain the natural structure of the leather and for a time sufficient to permit the chips and/or strips to swell and simultaneously cause the naturally occurring twisted and tangled collagen fibers therein to shrink and in so doing cause the twisted and tangled 00 fibers to automatically loosen and become less twisted and tangled; drying the steam-heated chips and/or strips; and pulverizing the dried chips and/or strips.

A second aspect of the invention provides a leather resin composition comprising: to 95% by weight of a synthetic resin; and to 80% by weight of the powder of the first aspect of the invention.

A third aspect of the invention provides a leather polyvinylchloride composition comprising: 100 parts by weight of a polyvinylchloride; 'iI' 8 0 to 150 parts by weight of a plasticizer; and 80 to 200 parts by weight of a granular nonflocculating resin-compatible leather powder of the first aspect of the invention.

A fourth aspect of the invention provides a process for producing a leather-resin molded product, which comprises the steps of: blending a liquid resin with a granular nonflocculating resin-compatible leather powder of the first aspect of the invention; molding the blend into a molded article; abrading the exposed surface of the molded article; r immersing the molded article in hot water for a period sufficient to leach out at least a portion of the leather powder from the surface of the molded article; and whereby upon completion of the leaching the surface of the molded article is effectively etched with *Poo 00 fine pores.

oe 0 A fifth aspect of the invention provides a 0 6 process for producing a leather-resin paint in which the carrier is a liquid resin paint, which comprises blending .0000 the liquid resin paint with a granular non-flocculating resin-conimpatible leather powder of the first aspect of the invention.

Typically, the leather powder does not agglomerate nor flocculate but maintains a granular state during the process of its manufacture, storage, or when mixed with synthetic resin, and a process for producing the same.

A leather-resin composition may comprise a 7E pL 9 mixture of a synthetic resin and a leather powder evenly distributed in the resin so as to provide articles having both the desirable properties of leather and of resin molding. An article having a leather-like surface layer may be produced by the use of the composition or an article such as sheet or the like.

A foaming-molded article may be produced by molding a synthetic resin containing the leather powder therein into a molded article such as sheet or the like followed by foaming the molded article.

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A paint containing the leather powder may be produced by uniformly dispersing the leather powder in a oe 15 liquid comprising a synthetic resin such as a synthetic resin emulsion.

e• 0. so: A coating material may be produced by effectively mixing the leather powder with a synthetic resin solution, synthetic resin emulsion, or molten synthetic resin (liquid polymer, etc.), or to provide a film for me..

decalcomania films or laminates. The decalcomania films would be formed by coating the coating material on a release paper (polyester film, etc.) having a grain pattern, drying, laminating on a nonwoven fabric, woven fabric, knitted fabric, etc., and finally removing the release paper.

•oeSo o e An adhesive for films or sheets may be produced by effectively mixing the leather powder with a synthetic resin solution, emulsion, or molten resin (liquid polymer, etc.).

A molded article having a leather-like surface may be produced by adhering the lather powder onto the surface of the molded article, I I Conveniently, the invention may allow a process for pulverizing a leather to make it "granular" rather than "fibrous". Typically the granules do not become entangled permitting the production of finer powders which will not flocculate and which will have an apparent specific gravity of about 0.3o to 0.8 g/cc. Granular powder may not require special separation techniques, and relatively larger grains can be used and be mixed well with resin because of their typically high lubricity permitting uniform distribution in the molded product.

This permits "loading" (increase of the amount of powders ordinarily used) without exerting a bad influence upon the resultant product.

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S 15 An article formed from the powder may display an excellent heat insulating factor and may be soft to the touch and not sticky.

An article formed from the powder may display both properties peculiar to natural leather and properties peculiar to molded resin, i.e. a natural lustrous leather-like appearance, softness, toughness, and durability.

ooo Advantageously, the invention allows the utilization of waste material such as scraps of various leathers in various shapes and sizes heretofore sea* discarded.

A leather-resin composition comprising the leather powder may be capable of providing molded products which due to their porosity have controlling functions similar to those of natural leather enabling air to permeate even when moisture is absorbed therein.

Conveniently such a leather-resin composition can be molded, extruded, or otherwise formed into sheet NTi IA~ 11 material which is lustrous and has an excellent feel.

The leather-resin composition of the invention may prevent static build-up and adherence of dust to a product made therefrom as well as elimination or reduction of static discharge.

Typically the leather-resin composition has high heat insulating properties.

The invention may allow the pulverizing simultaneously of various different types of leathers or 0:00 rawhides whether of young animal or adult or of different se types of animals.

0 1 Advantageously production of the leather powder 00090 avoids the entanglement of the fibers or the unravelling which make it difficult to mix with synthetic resin.

Typically production of leather powder reduces abrasion and damage on machinery dies and other tools 0000 used in the production of molded products.

The leather-resin composition will usually have 0 sufficient fluidity to prevent problems during embossing operations with a pressure roller, rolling operations for patterning grain pattern, or production operations.

0000 .A paint containing the leather powder will generally smoothly flow without agglomeration or condensation permitting formation of a film without surface defects when applied, and may provide a paint capable of providing a film ir coating which will stand up under hard conditions without cracking, crazing, or the like.

The growing importance of computers and other 1L>I 9 ,6 1 j 12 sophisticated machinery in today's complex world is axiomatic. Plastics are an indispensable part of such equipment. Higher quality plastics facilitate the production of even more advanced equipment. The leatherresin composition may be used for producing plastics articles which are absorbent, supple, attractive to the eyes, and similar to natural leather, and which may have the same texture and touch as natural leather with pliancy at temperatures as low as -40°C, with a feeling of warmth in cold weather and coolness in hot weather.

The leather-resin composition which can be processed with leather working equipment into suede, embossed leather, shrunken leather, corrected grain e. s. 15 leather, enamelled leather, or matte leather. by embossing, it can take on the texture of crocodile, ostrich, elk leather, etc.

Conveniently the leather-resin composition may further including gelatin and be capable of providing articles which are not sticky to the touch, are air permeable so that they are resistant ot water and *0 0 abrasion, and do not mold or fade.

*soi* 25 The leather-gelatin-resin composition is typically cleaned and dyed easily and treated like .natural leather with shoe polish, leather cleaner, or the like.

0 Furthermore, the leather-gelatin-resin composition is generally electro-conductive and resistant to static electricity and does not readily attract dust.

The leather-gelatin-resin composition is typically superior to ordinary plastics in absorbing properties, toughness, and oil-resistance and may be more adhesive than ordinary resin when in the fluid state.

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13 The leather-gelatin-resin composition when used on tool surfaces may be more stable on wet or frozen roads than synthetic rubber and may display excellent vibration and impact resistances.

The leather-gelatin-resin composition is generally easier to shape, inject or extrude than ordinary resins and retains its stable resilient qualities even under temperatures as low as -40 0

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In summary, the present invention relates to a leather powder which can be used in the production of I furniture, utensil, paint or molded articles or in the 15 production of leather type products for use in the automobile, shipping, or aircraft industries or the like; o 0

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14 process for producing the same; a leather-resin composition containing the leather powder; and a process for producing a paint containing the leather powder.

BRIEF DESCRIPTION OF THE DRAWING In the accompanying drawings which illustrate by way of example various embodiments of the present invention; FIGURE 1 is a schematic view of an apparatus for heating leather with steam.

FIGURES 2 and 3 are schematic views of an apparatus for classifying the pulverized leather according 'to the grain size.

FIGURES 4, 5, and 6 are electron-microscopic enlargements magnified 100 times of leather powder 0.

pulverized by a prior art methods.

FIGURES 7 and 8 are photographic views showing the front and back of a calender-rolled sheet using leather ,powder pulverized by a prior art method.

FIGURE 9 is a photographic electron-microscopic view magnified 101 times showing the leather powder according to the present invention.

FIGURE 10 is a photographic electron-microscopic view of the leather powder magnified 100 times produced by an embodiment of the process of the present invention.

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FIGURE 11 is a graph showing the grain size distribution of the leather powder produced by another embodiment according to the present invention. In this figure, the ordinate represents the amount of distribution in by weight and the abscissa represents the grain size in microns. Numerical values given in the graph represent the amount of distribution in by weight.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In order to obtain a fine powder having an apparent specific gravity of about 0.38 to 0.8 g/cc, which will not cake or agglomerate when mixed with a synthetic resin, it is necessary to heat the tanned leather with steam. When a rawhide is used as the raw material, it should have been tanned with chrome, tannin, etc. prior to steam-heating.

First the tanned leather is shredded into chips or strips. Strips initially of about 30 mm length were utilized; however, as shaven scraps are long and twisted, S it is desirable to cut them to a size of about 5 mm prior to steam-heating.

The steam-heating is continued until the apparent specific gravity of the leather powder to be produced reaches about 0.38 to 0.8 g/cc. Duration of the steamheating varies depending on the nature and amount of the .L'.LL Il ''ii LJJ tna Lz CL lCItAJl .l .L I 16 leather to be treated, pressure and temperature of the treating chamber, etc.

Chips and/or strips after cutting are charged into the closed treating chamber 1 as shown schematically in Figure 1. The treating chamber 1 is equipped with an agitator diagrammatically shown by a reference numeral 2 permitting to steam-heat during agitating. A steam jacket 3 encloses the chamber 1. Steam A is fed into steam line 4 and exhausted from steam line 5. A valve 6 controls the pressure in the chamber 1 to about 1 kg/cm 2 G. It is desirable to maintain the temperature in the chamber to

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about 100 to 119 "C and to agitate the charge for at least about 20 minutes, more preferably for at least about minutes with-agitating.

The steam-heating is designed to increase the water content of the charge\by about 5 to 10 by weight depending on the type of the charged leather. The steam jacket 3 is provided with a steam in-feed line 7 and steam exhausts at B' through line 8 having a control valve 9.

Steam A as well as steam B is fed into the chamber 1, and exhaust steam A' is exhausted from the chamber 1 through steam line 5 having a control valve 6. Resultingly, the chips and/or strips swell and naturally twisted and tangled collagen fibers automatically loosen and become less PLIAi twisted and less tangled.

1 1 17 The jacket 3 is used to simultaneously heat from the outside as well as from the inside so as to adjust the water content in the leather conveniently to about by weight or less (primary drying).

A secondary drying may be necessary to reduce the water content to less than about 5% by weight, ideally to less than about 3% by weight. The resultant charge is subsequently pulverized into a powder.

The use of split or shaven leather which has been tanned with chrome or tannin will generally prevent fungus and deterioration of the powder during processing.

Heating time in the chamber is determined by the temperature of the steam, pressure, type of the charged chips and/or strips, etc. The steam-heating is maintained for a sufficient time at a temperature typically ranging from about 100 to 119 0 C to permit the collagen fibers in the c-hips and/or strips to be swollen facilitating unravelling. The fibers tend to shrink upon heating thus permitting the fibers to take on an appearance of unravelled cotton and loosen prior to pulverization.

Generally, steam of a pressure of from 0.5 to kg/cm 2 G is used. However, steam of a pressure of about 1.5 kg/cm 2 G is preferably used since the heating time necessary for attaining desired swelling effect becomes shorter the higher the temperature and pressure of steam S 30 is.

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18 If the temperature and pressure are too low, the treating time of the step will be prolonged to be unsuitable to actual production. As chrome or tannin tanned leather having been steam-heated for swelling becomes dry, the collagen fibers shrink and loosen and become somewhat disentagled with each other.

Leather not tanned becomes hardened after drying making it impossible to pulverize the same. Further, the leather not tanned gelatinizes progressively making it difficult to obtain collagen fibers, and becomes flocculent making it impossible to granulate. It was found that, 'ft where the leather had not swelled fully, the resultant powder flocculates and had an apparent specific gravity of 0.2 to 0.3 g/cc which was below the required of about 0.38 to 0.8 g/cc. The apparent specific gravity of the leather powder higher than 0.8 g/cc is undesirable because the 4 leather powder becomes hard due to gelation and loses the properties particular to natural leather such as hygroscopicity. Prticularly, apparent specific gravities of from 0.38 to 0.5 g/cc, more particylarly of from 0.38 to 0.6 g/cc, are preferable. The fact shows that the steamtreatment makes it possible to produce the leather powder having the apparent specific gravity of the required range more commercially efficiently than other conventional methods. It was also found that the leather not tanned i b--L ICi--n 19 became flocculent making it impossible to obtain the apparent specific gravity of the range.

It was also found that if the leather had an extremely low water content (20 to 30 by weight) before steam-heating, the resultant leather powder obtaineda-J.-& flocculate and 4had\an apparent specific gravity too low of 0.2 to 0.3 g/cc. Leather powder having an apparent specific gravity lower than 0.3 g/cc is unsuitable for practical use. Further, if leather is heated in hot water, that is, substantially boiled, it will harden and become unsuitable for use despite subsequent treatments.

Pulverization is carried out using a pulverizer such as a Fine Victory Mill (not shown). It is desirable to conduct the pulverization so that the average micron granule measured with a Coulter Counter (produced by .9 Coulter Electronics Co.) is adjusted to less than 100 S* microns and the granule size does not exceed about 150 microns. Hereinafter, grain sizes represented in microns were measured using a Coulter Counter.

It is desirable to classify the obtained leather powder out by use of a sieve or air classifier. It is desirable to conduct sieving so as to classify into 40 to 300 mesh, 200 to 300 mesh, 100 to 150 mesh, or the like.

Also it is desirable to conduct the classification so as to size into at least two classes including one larger

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granular size class and one smaller granular size class.

When the leather powder was mixed with various synthetic resin such as polyvinylchloride depending on the purpose, it was found that itbecame evenly mixed and uniformly distributed in the molded product. Neither flocculation nor caking occurred in the powder and each discrete grain was dispersed in the molded product. The resin composition containing the leather powder can be extrusion or injection molded in the same manner as the conventional resins, and as well prevents friction in machineries.

Also, when the leather powder is mixed with a paint, particularly with resinous coating solutions, the leather powderdoes not flocculate but intimately mixes and as well distributes uniformly. This makes it possible to form a thin layer containing the leather powder by *application of the above described paint. Because the grains of the leather powder is considerably fine, the surface of the applied layer willnot be affected thereby and thus become smooth and uniform.

It is also possible to produce an extremely thin resin film (10 mg 100 mg especially decalcomania film for lamination using the leather powder without causing deformation or warp on the surface. In the example where by weight of grains is smaller than 40 microns, the S 100 parts by weight of a polyvinylchloride; i: i i 21 majority of the grains is approximately 100 microns or less and more particularly 40 microns or less. The leather powder may be used to form a film on a release paper and then laminated on the surface of cloth, paper, resin film, leather, etc.

The attached graph (Figure 11) shows the grain size distribution in by weight measured by classifying the powder with a classifier and suspending it in methyl alcohol to measure the size using a Coulter Counter.

*i It is apparent from the graph (Figure 11) that the powder contains 78.7 by weight of fine powder with the size of 40 microns or smaller. As mentioned above, a powder having grain sizes slightly greater than such a size can also be used in mixing with the paint or coating t material. Experiments conducted by the inventor revealed that a leather powder having a grain size slightly greater S* than 40 microns also can be mixed with the paint or coating material. Experiments conducted by the inventor further "revealed that a good result can be obtained if more than weight of the leather powder is of a grain size smaller than 40 microns and if grains exceeding 150 microns are effectively removed.

Fat removing treatment, if necessary, may be conducted because leather powder mentioned above may become discolored if its fats and oils content is high.

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9 The treatment for removing fats and oils ascarried out by using a solvent such as benzine, methyl chloride, methylacetone, and ethyl acetate, which elutes fats and oils from the leather. With another treatment for removing fats and oils, the leather is washed with hot water and the fats and oils content is elutes from the swollen leather. When using a solvent, the leather should preferably contain less amount of water. Therefore, the leather is ideally subjected to this elution treatment with the solvent either in the stage prior to steam heating, in the stage of drying after steam-heating, or after the stage of pulverization after drying.

The leather powder thus obtained can be dyed if desired. Suitable dyestuff and method for dyeing must be selected depending on the properties of the leather powder.

For instance, if the leather powder obtained from a chrome tanned leather, acidic dyestuff having a good level dyeing property and penetrability such as mono-azo, anthraquinone, and carbonium dyes may be suitably used. For a leather treated with tannin, basic dyestuff such as azo, azine, and thiazine dyes. Acidic mordant dye, direct dye, or reactive dye is also added depending on the use, properties of the leather powder, etc., and dyeing was conducted under moisture and agitation. After dyeing, the leather powder is dried.

00108, 1 uurugm, ri -r a 0* 0 0* 03 3* 3. 00 The dyeing can be conducted concurrently Nvith steam-heating, or alternately, it can be conducted as a separate step under moisture after pulverization has been completed. Optimum methods can be employed to suit the conditions of each plant.

Using the leather powder classified by a 40 mesh sieve and mixed with synthetic resins such as polyvinyl chloride, various resin moldings can be obtained.

Illustrative examples of the synthetic resins that can be used in mixture with the leather powder of the present invention include thermoplastic resins such as polyvinylchloride, polyvinylacetate, vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinylidene chloride copolymer, vinylidene chloride-acrylonitrile copolymer, butadiene-acrylonitrile copolymer, butadiene-styrene copolymer, polyethylene, polyurethane, polyamides, ABS resin, polycarbonates, and polyacrylates; thermosetting resins such as phenolic resin, epoxy resin, and urea resin; and synthetic rubbers such as chloroprene base rubbers, butadiene base rubbers, styrene base rubbers, olefin base rubbers, and polyurethane base rubbers.

As a typical example, non-rigid polyvinylchloride is used in mixture with the leather powder of the present invention in the following blending ratio. (The values are expressed in by weight, and "synthetic resin compound"

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De mol±ea, extruded, or otherwise formed into sheet L 1_ 24 means a mixture of resins, plasticizer, stabilizer, etc.) For molding sheets: leather powder 5-55 synthetic resin compound 45-95 (synthetic resin compound containing 2-15 of gelatin) For molding bars, plates, and masses such as armrests for chairs, wall, and furniture; automobile interior frames such as console boxes, handles, and grips: leather powder 20-80 *t synthetic resin compound 20-80 For moldings containing industrial gelatin: leather powder 5-70 synthetic resin compound 30-95

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(synthetic resin compound containing 2-15 of gelatin) For preparing intermediate material such as pellets: leather powder 5-80 synthetic resin compound 20-95 Leather-like moldings of high quality were Leather-like moldings of high quality were

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*B 9 obtained from any of the above compositions. The suitable weight ratio of the gelatin is about 5 The above compositions are suitable for molding soft, semi-hard moldings, and provide features adequate for each hardness. Also foamed moldings can be obtained by foaming the mixture of leather powder and resin compound at the production of the above films, sheets and plates, bars, or masses causing formation of continuous or non-continuous intervals between the leather powder and the resin.

The leather powder shown in Figure 11, which is obtained by classifying the pulverized leather powder, due to its very fine grain size exhibits excellent lubricity and is sufficiently dry, and thus mixes well with resin compound.

Particularly, when 5 to 45 by weight of the leather powder is mixed with various synthetic resin solutions (solution, emulsion, or molten synthetic resin solution containing liquid polymer) and coated over cloth, nonwoven cloth, paper, synthetic leather, or leather, sheet products having a leather-like surface can be obtained.

Similarly, when coated on metal products or resin moldings such as furniture, automobile interior parts, and the like (by means of brush, spraying, etc.) for a thickness of 0.01 to 0.1 mm, a coated surface having a leather-like appearance can be obtained.

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1 I.- 26 When the leather powder is used for paint, the paint wherein the leather powder is mixed may be any of the commercial paints. As a typical example, when the synthetic resin solution was a polyurethane solution (either one-liquid type or two-liquid type), the film surface obtained had a better leather-like appearance.

Further, when the paint containing the classified leather powder is used for coating by means of spraying, etc., more even coating surface can be obtained by grinding a the paint mixed with the leather powder, with a ball mill, em p. sand mill, etc. prior to utilization. In such a manner, a ag, leather powder of an average grain size of 30 g m can be diminished to 10 u m or smaller by grinding the mixture of paint and leather powder, in a solvent such as toluene, p.

MEK, xylene, DMF, etc., and thus plugging in spray is prevented facilitating spray coating, and an even film 4surface can be obtained.

Also the classified leather powder can be adhered S* to the surface of resin molding, cloth, nonwoven cloth, a.u* paper, leather, synthetic leather, etc. with an adhesive.

Thus obtained molded products had an even surface without projection in the surface la:yer due to flocculation of the leather powder.

iwf.6^ t8g ^a r( 27 Post treatment for molded products The surface of the molded products thus obtained q VIe- 4-&\sanded or sand blasted to expose the leather powder content to the surface.

By immersing the product in hot water, a portion of the above-mentioned gelatin or leather powder contained in the product can be induced to seep out and form fine pores on the surface.

0** The surface of products may be embossed with special patterns (such as a pattern of a crocodile skin).

em S*Dyes and oils for leathers can be used for the a.

leather articles of the present invention in the same manner as in the ordinary leathers.

As is evident from the foregoing, ayytypesof 5* resin moldings can be produced using the leather powder of 9• the present invention. The leather powder can also be used for spraying, coating, laminating, or the like. It is therefore possible to use the leather powder in molding everything that is used in daily life.

S *The present invention will be better understood by the following non-limitative Examples.

EXAMPLE 1 600 kg of scraps of chrome tanned cow leather 3 5 mm width, 30 50 mm length, 0.5 mm thickness) were cut AJ rL 28 into chips of 5 mm length, and the chips were charged into a closed treating chamber shown in Figure and then steamheated at a treating chamber temperature of 110 °C at an agitator rotation of 16 rpm, for 30 minutes. The raw material had a water content of 53 by weight before the steam-treatment and a water content of 59 by weight after the steam-treatment The measurement of water content was conducted by means of thermo-ballance method using FD-220 type produced by Kett Co.).

Subsequently, using internal heating with dry air .o and external heating with heated steam in combination, drying was conducted until the water content in the raw S material was reduced to about 3 by weight.

The leather chips thus obtained was pulverized using a Fine Victory Mill.

The Fine Victory Mill was operated at rotation of 7000 rpm, no-load/loaded operation at 17.2/20 (ampere) with a slit half opened (Example 1A). In another example or operation, the rotation was 7800 rpm, no-load/loaded operation at 15.8/20 (ampere) and with the slit full opened (Example 1B).

As the slit is widened, return of the pulverized leather powder increases and thus frequency of pulverization increases providing more fine grains.

The leather powder thus obtained was classified heating varies depending on the nature and amount of tne

I

29 using sieves of 40 to 300 mesh and the grain size distribution was studied.

Example 1A Under Sieve Above Sieve Distribution Amount 60 mesh 2.8 80 mesh 9.7 100 mesh 9.7 100 150 mesh 25.7 150 200 mesh 13.9 so 200 300 mesh 33.7 0e 300 mesh 4.5 mesh" of "Under Sieve" means the leather powders which passed 40 mesh sieve and "60 mesh" of "Above Sieve" means the leather powders which did not pass 60 mesh sieve.) The leather powder was measured to have an 0* *S *0 *0 apparent specific gravity of 0.40 g/cc.

Leather powder was obtained by a similar 0m -0 0".0 treatment except that in the steam-heating stage a brown- Scoloring process using a leather dye was included. The grain size distribution of the obtained leather powder is shown as follows.

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Under Sieve 100 150 200 300 mesh Example 1B Above Sieve 60 mesh 80 mesh 100 mesh 150 mesh 200 mesh 300 mesh Distribution Amount 5.7 7.0 5.7 39.4 30.0 12.2 0 *0 0 *0 0 0

S.

0 Coloring treatment makes the grain size somewhat larger than that of non-colored leather powder.

Leather powder having the above grain size distributions, are suitable for use in mixture with various resin materials for molding. Any type of molding methods such as calender roll, extrusion, or injection can be used.

The leather powder was measured to have an apparent specific gravity of 0.42 g/cc.

The apparent specific gravity as used in the present specification is an aerated bulk density. That is, leather powder is charged into a vessel of 100 cc capacity through a sieve by shaking the same and is weighed after leveling off at the top of the vessel. The values are expressed by dividing the powder weight (grams) with 100 (cc).

900108.17 31 EXAMPLE 2 Using an air classifier, the leather powder obtained in the above Example 1A was classified into different classes for use in thin films or layers for adhesion, coated film, laminate film according to the true specific gravity.

This classification will be described in conjunction with Figures 2 and 3. The reference numeral 11 represents a feeder which introduces the above-described leather powder and continuously feeds the same into an air classifier 12 (Micron Separator). The air classifier 12 0S*** has a rotor 12a which suctions and classifies the leather powder supplied via an inlet port 12b according to the true specific gravity. A turbo-fan 13 feeds the leather powder into a back filter tank 14 for classification. Coarse powder is classified and taken out from a rotary valve 12c and fine powder from a rotary valve 14a. The reference numeral 12d represents a secondary air inlet, and 12e an S" outlet for classified fine powder.

Using the classifier of the above construction, kg of leather powder was treated with the rotation of the rotor 12a at 600 rpm, secondary air supply of 4.0 m 3 /min, and air for dust collection of 12 m3/min, and 2.05 kg of fine powder was obtained.

32 As is seen in the graph (Figure 11) showing the grain size distribution, the fine powder thus classified had an average grain size of 24.5 microns, with the majority having that of less than 50 microns. The apparent specific gravity of the fine powder was 0.45 g/cc.

With the fine powder thus obtained, the powder grains do not become entangled with each other and each discrete grain is present without flocculation or caking.

EXAMPLE 3 a.

(Conventional leather powder) Figures 4 through 6 are microphotographs of test a samples of leather powder produced by pulverizing a leather which has been tanned with chrome and shredded into strips of about 30 mm in length. The resultant material was dried to a water content of about 5 by weight (on a wet bases)(or 1.9 5.0 in the actual pilot plant) and charged into a hammer-type pulverizing mill under the following conditions: Rotation 3800 rpm Sieve screen 32 mesh Charged material 0.2 kg Treatment time 27 sec Amount of product 0.2 kg i the Led arent ier h ing.

test eather trips dried Upon pulverization under the foregoing conditions, the leather powder having the following grain size distribution was obtained as measured in shorter diameter when the grain was fibrous).

*900 0 0 4.

0 00 Under Sieve 32 48 60 100 150 mesh Above Sieve 32 mesh 48 mesh 60 mesh 100 mesh 150 mesh Distribution Amount 0.8 9 2.4 8.2 %6 15.5 18.4 54.75 0000 0000 0 do *00 0 9 00 *0 0 90 0 0 00 0 0 0 0 r"cxh 0000 0000 000000 The charge was not treated with steam.

The resultant specific gravity of the leather powder thus obtained was very low as 0.1 to 0.2 g/cc. The images in Figures 4 through 6 are enlarged by 1.6 times at the time of printing. Although grains finer than 150 mesh were predominant in the powder, longer fibers that is more coarse than 60 mesh, especially than 48 mesh, were also present, lowering the apparent specific gravity.

The test results were defective in that the longer fibers became entangled and unraveled depending on

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34 the types of leather used whether from cow or pig, young animal or adult, etc. The tendency became more pronounce in the transition from the pilot plant to actual production. During storage, the grains of powder became entangled and appeared as of unraveled cotton. When mixed with synthetic resin, the powder flocculated and became difficult to mix.

Figures 7 and 8 each shows a molded product produced from a mixture of the leather powder produced by the above-mentioned method and the synthetic resin. Figure 7 shows the front and Figure 8 shows the back surface of a sheet by a magnification of ca. 2.6 times, the sheet being 4 molded with a calender roll using a mixture of vinyl chloride resin (produced by Shin-Etsu Chemical Co., Ltd., SHIN-ETSU PVC TK-1300, mean degree of polymerization: 1300). Cotton-like flocculated materials show

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irregularities on the surface of the sheet. This indicates that the resin and the leather powder are not mixed evenly and do not give uniform distribution. In extruding process, such a flocculation causes wear on the equipment.

If such a material is used in a paint, the flocculated powder tends to clog the nozzle of the spray gun.

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EXAMPLE 4 (Leather powder) Figure 9 shows microphotograph of the leather powder that was collected with a 40 mesh sieve from the leather powder produced by the coloring method of Example 1 B. 5 kg of the classified powder was charged into an air classifier and 2.05 kg of fine powder was obtained. Figure 10 shows microphotograph of the classified leather powder.

Figure 9 shows absence of fibers and presence of grains individually dispersed in the powder maintaining a "granular state". As shown in Figures 4, 5, and 6, the

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conventional leather powder contains relatively larger long fibers. Using the classifier 12, 5 kg of leather powder was treated with the rotor 12a at 600 rpm, secondary air supply of 4.0 m 3 /min, and air dust collection of 12 m 3 /min, and 2.05 kg of fine powder was obtained. The classified fine powder had an average grain size of 24.5 microns, and the majority was smaller than 50 microns. The apparent age. specific gravity of the fine powder was so high as 0.46 g/cc. As compared with Figure 9, Figure 10 shows superior uniformity and higher apparent specific gravity. It should be also noted that the grain size is smaller and there is no fibers nor tangling.

It was determined from the various tests conducted that leather powders having an apparent specific ,i i.

~~rrvi ~Tfl 36 gravities greater than 0.38 g/cc contain no entangled or ciliary fibers.

Apparent specific gravities exceeding 0.8 g/cc are undesirable because the leather powders having such apparent specific gravities tend to gel and harden losing properties particular to leathers such as hygroscopicity.

The powder shown in Figure 9 was filtered using a mesh sieve and had an apparent specific gravity of 0.42 g/cc.

The powder shown in Figure 10 contains 70 by weight of grains smaller than 40 microns (as measured in smaller or shorter diameter if the grain was elongated).

Although this powder was extremely fine and had a grain size of 40 microns or less, the powder did not flocculate in any of the processing, storage, or molding steps with resin.

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9 SS

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*0eS 5595 S EXAMPLE A resin composition comprising 100 parts by weight of the same vinyl chloride resin as used in Example 3, 100 parts by weight of di-2-ethylhexyl phthalate (DOP) as plasticizer, and 25 parts by weight of the leather powder obtained in Example 1A was calender-formed into a sheet and was laminated on a knitted fabric of polyester.

As a finishing agent, on the sheet was gravure-coated a

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11 OA WI 37 liquid resin composition containing 100 parts by weight of urethane resin and 30 parts by weight of the leather powder having the grain size distributions of Figure 11 mixed therewith in 20 n m thickness. When the laminate sheet was grain-processed to give a leather pattern, a sheet having a good texture without sticky touch and thus excelling conventional ones.

EXAMPLE 6 oo (Paint) c. *The leather powder having the grain size distribution of Figure 11 and a solution of two-liquid S S reactive urethane type paint in toluene were agitated with a ball mill, .and a hardener, isocyanate, was blended •thereto. The blend was coated with a spray gun to obtain a coated film of 40 #I m in thickness.

The film had an excellent matted surface and was good in the touch without giving sticky feeling.

The amounts of the leather powder added are shown in the following table in by weight of leather powder based on the total amount of polyester and leather powder in the two-liquid reactive urethane type paint. The glossiness was determined by 60" -reflecting method.

-AA I JL -L n -LH JL LL. II&- t, 38 Leather powder amount 0 10 20 30 Glossiness 81.2 58.2 36.6 3.0 0.4 SEXAMPLE 7 (Decalcomania film) A mixture of 30 parts by weight of the leather powder shown in Figure 11 diluted with a solvent and 100 parts by weight of urethane resin was coated on a release

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paper and dried. The film of 60 g m thickness thus obtained was transferred and adhered to a woven fabric to obtain a laminate film.

The laminate film had a good surface and was also 4 excelled in the touch without sticky touch.

EXAMPLE 8 (Defatted leather powder) The leather powder shown in Figure 10 (water content: 5 by weight, fats and oils content: 6.3 by weight) was agitated in toluene with heating to remove the Ij C. C

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a fats and oils content. The ratio of the leather powder and the toluene blended was leather powder/toluene 1/5, and the heating temperature was 60 °C With two hours agitating, the fats and oils content was reduced to 0.5 by weight, and subsequent washing with fresh toluene reduced the fat content to less than 0.2 by weight. The measurement of fats and oils content was conducted according to JIS-K-6550.

Between a couple of glass plates of 50 mm by mm was enclosed the leather powder thus obtained in thickness of 1 mm and was subjected to light fastness test according to JIS-L-0842 at a black panel temperature of 83 *C The leather powder remained not discolored after 100 hours.

EXAMPLE 9 (Sheet) A resin component having the following composition was formed into a 0.2 mm thick sheet by calender technique.

Vinyl chloride resin 100 parts by weight (produced by Shin-Etsu Chemical Co., Ltd., TK-1300, Mean degree of polymerization: 1300) DOP 90 parts by weight Leather powder 83 parts by weight (obtained in Example 1A) In comparison with polyvinylchloride sheets, the sheet thus obtained was without sticky touch and excellent in feeling. Also it excelled in the hydroscopicity.

EXAMPLE (Foamed leather) 0 Upon a polyester knitted fabric was placed a sheet consisting of the following and [III] in this order with on top, and was heated to obtain a foamed sheet.

C S

[B]

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[I]

Vinyl chloride resin 100 parts by weight (Produced by Shin-Etsu Chemical Co., Ltd., TK-1300, Mean degree of polymerization: 1300) DOP 90 parts by weight Leather powder obtained in Example 1A parts by weight

[II]

Vinyl chloride resin 100 parts by weight (Produced by Shin-Etsu Chemical Co., Ltd., TK-1300, Mean 41 degree of polymerization: 1300) DOP 90 parts by weight Chemical foaming agent 4 parts by weight Leather powder obtained in Example 1A parts by weight

[III]

Vinyl chloride resin 100 parts by weight (Produced by Shin-Etsu Chemical Co., Ltd., TK-1300, Mean degree of polymerization: 1300) DOP 90 parts by weight In comparison with foamed polyvinylchloride sheets, the foamed leather thus obtained was without sticky touch and excellent in feeling.

~EXAMPLE 11 (paint) With MEK solvent, liquid urethane resin (produced Sby Dainippon Ink Chemicals, Inc., yellowing one-liquid type polyurethane 3006 LV, non-volatile matter content: was adjusted to a viscosity of 20 to 50 poise (25 C Into 100 parts by weight of the above-described urethane resin was added 50 parts by weight of the leather powder shown in Figure 11, and was mixed with a ball mill during i i IQiwuP~-l r~uu ir 42 diluting with toluene until the viscosity reached 100 poise 0C Thus obtained mixture was coated to a PVC plate with a spray gun and was then dried for 1 minute at 100 "C to obtain a leather-like coated film. When the surface of the coated film was baffed with 240 mesh sandpaper, a suede-like coated film was obtained.

The coated film did not have sticky touch excelling conventional ones and therefore can serve as a very effective flatting material.

EXAMPLE 12 (Adhesion) Upon a release paper, a mixture solution obtained by adding 30 by weight of the leather powder shown in Figure 11 to a one-liquid type urethane resin (non-volatile matter content: 30 by weight, MEK (25)/DMF (75) solvent *ee mixture, the numerals in the parentheses representing S" mixing weight ratio, ca. 600 poise at 20 °C was coated with a coating head and was then dried.

A mixture of two-liquid type urethane resin (nonvolatile matter contenL: 50 by weight, MEK solvent, 400 poise at 250 "C and 30 by weight of leather powder was further coated to the film and was adhered to a nonwoven fabric by lamination. The product thus obtained had a bonding strength equal to that of these not containing ^iAL7i~s oo^=A^.

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Claims (19)

1. A process for producing a granular non- flocculating resin-compatible powder having an apparent specific gravity of 0.38 to 0.8 g/cc from a tanned animal leather, which comprises the steps of: providing a tanned leather cut into chips and/or strips; steam-heating the chips and/or strips to substantially retain the natural structure of the leather and for a time sufficient to permit the chips and/or strips to swell and simultaneously cause the naturally occurring twisted and tangled collagen fibers therein to shrink and in so doing cause the twisted and tangled 0 fibers to automatically loosen and become less twisted and tangled; drying the steam-heated chips and/or strips; 'and pulverizing the dried chips and/or strips.

2. The process according to claim 1 wherein the powder has an apparent specific gravity of 0.38 to C.6 g/cc.

3. The process according to claim 1 or claim 2 wherein the chips and/or strips are steam-heated at a ,a temperature in the range 100 to 119 0 C at the steam- heating step

4. The process according to any preceding claim wherein the water content of the chips and/or strips is increased by 5 to 10 by weight at the steam-heating step The process according to any preceding claim wherein the chips and/or strips are dried so that the Swater content of the chips and/or strips is decreased to i i i Li~ll lili--C1 44 less than 5 by weight at the drying step

6. The process according to any preceding claim wherein the chips and/or strips are steam-heated at a temperature in the range 100 to 119 0 C for at least minutes while stirring at the steam-heating step

7. The process according to any preceding claim wherein the granules obtained at the pulverizing step (d) are classified with an air classifier to remove dust and to size the granules by grain size into at least two 0006 classes including one larger grain size class and one smaller grain size class.

8. The process according to claim 7 wherein the classification of the granules with an air classifier is conducted so that granules containing more than 70 by weight of powder of a grain size of less than 40 microns are obtained. 0000

9. The process according to any preceding claim wherein fats and oils are removed from the tanned leather prior to the steam-heating step The process according to any preceding claim 0060 wherein fats and oils are removed from the chips and/or strips after the steam-heating step

11. The process according to any preceding claim wherein fats and oils are removed from the chips and/or strips at the pulverizing step or are removed from the pulverized product obtained upon completion of the pulverizing step

12. The process according to any preceding claim wherein the granules obtained by pulverizing the chips iL a-A and/or strips are classified so that the average micron -r -r r- i~~e 1. I 7_ I size thereof is adjusted to less than 100 microns and the grain size does not exceed 150 microns.

13. A leather powder produced by the process according to any one of claims 1 to 12 and 23.

14. A leather-resin composition comprising 20 to 95 by weight of a synthetic resin; and 5 to 80 by weight of a granular non- flocculating resin-compatible leather powder according to claim 13. 0 0 go

15. The leather resin composition according to claim 0. 14 wherein the synthetic resin is selected from the group consisting of polyvinylchloride, polyvinylacetate, ABS resin, polycarbonate, phenolic resin, epoxy resin, urea resin, polybutadiene, polystyrene, and polyolefin.

16. The leather-resin composition according to claim 14 or claim 15, further comprising a plasticizer and/or a stabilizer for the synthetic resin. ease*: 0

17. The leather-resin composition according to claim 16 wherein the synthetic resin contains 2 to 15 by *ooo* weight of an animal gelatinous protein. 0

18. A leather-polyvinylchloride composition comprising: 100 parts by weight of a polyvinylchloride; 0 to 150 parts by weight of a plasticizer; and 80 to 200 parts by weight of a granular non- flocculating resin-compatible leather powder according to claim 13. sL 19. A process for producing a leather-resin paint in longer fibers became entangled and unraveled depending on 46 which the carrier is a liquid resin paint, which comprises blending the liquid resin paint with a granular non-flocculating resin-compatible leather powder according to claim 13. The process according to claim 19 wherein the blended product is ground prior to application onto an article surface.

21. A process for producing a leather-resin molded product, which comprises the steps of: 00CC blending a liquid resin with a granular non- flocculating resin-compatible leather powder according to claim 13; .00 molding the blend into a molded article; abrading the exposed surface of the molded article; immersing the molded article in hot water for a period sufficient to leach out at least a portion of the leather powder from the surface of the molded article; and whereby upon completion of the leaching the surface of the molded article is effectively etched with fine pores. CCC. ooo. 22. The process according to claim 21 wherein the etched porous surface is subsequently embossed with a pattern.

23. A process according to claim i, 19 or 21, substantially as hereinbefore described with reference to the drawings and/or Examples.

24. A leather resin paint or a leather resin molded article produced by the process of any one of claims 19 to 23. ~iiih 47 A composition according to claim 14 or claim 18 substantially as hereinbefore described with reference to the drawings and/or Examples. DATED this 8th day of January 1990. IDEMITSU PETROCHEMICAL CO., LTD. By Its Patent Attorneys DAVIES COLLISON lot* UL I W1'6 47