US3682825A - Process for the production of electrophotographic liquid developer containing gelatin - Google Patents

Abstract

A PROCESS FOR THE PRODUCTION OF A LIQUID DEVELOPER FOR DEVELOPING AN ELECTROSTATIC LATENT IMAGE WHICH COMPRISES THE STEPS OF (1) DISPERSING IN AN ORGANIC SOLVENT WHICH IS MISCIBLE WITH WATER BUT IS A NON-WOLVENT FOR GELATIN, AN AQUEOUS SOLUTION OF GELATIN, THE CONCENTRATION OF THE GELATIN BEING IN THE RANGE OF APPOXIMAGELY 1 TO 20% BY WEIGHT, OR A SOLUTION OF GELATIN IN A MIXED SOLVENT OF WATER AND AN ALCOHOL PREPARED BY INCORPORATING IN THE AQUEOUS SOLUTION OF GELATIN AN ALCOHOL IN AN AMOUNT CAUSING NO PRECIPITATION OF THE GELATIN TO PROVIDE A DISPERSION OF GELATIN GRAINES WHERE THE AMOUNT OF THE ORGANIC SOLVENT IS AT LEAST TEN TIMES THE AMOUNT OF THE AQUEOUS SOLUTION OF GELATIN OR THE SOLUTION OF GELATIN IN THE MIXED SOLVENT OF WATER AND ALCOHOL TO BE ADDED THERETO, (2) ADDING TO THE RESULTANT DISPERSION OF GELATIN A SOLUTION OF A RESIN WHICH IS INSOLUBLE IN THE ORGANIC SOLVENT FOR SAID GELATIN DISPERSION BUT SOLUBLE IN A CARRIER LIQUID HAVING AN ELECTRIC RESISTANCE OF HIGHER THAN 10**10 CM. TO COPRECIPIATE THE GELATIN GRAINS AND THE RESIN, AND (3) ADDING THE PRECIPITATES OF THE GELATIN GRAINS AND THE RESIN TO THE CARRIER LIQUID MENTIONED ABOVE.

Description

United States Patent Office 3,682,825 Patented Aug. 8, 1972 PROCESS FOR THE PRODUCTION OF ELECTRO- PHOTOGRAPHIC LIQUID DEVELOPER CON- TAINING GELATIN Yasuo Tamai and Satoru Honjo, Asaka-shl, Japan, as-

signors to Fuji Photo Film Co., Ltd., Kanagawa, Ja an N: Drawing. Filed Feb. 3, 1970, Ser. No. 8,432

Claims priority, application Japan, Feb. 3, 1969, 44/7,944 Int. Cl. G03g 9/04 US. Cl. 252-621 9 Claims ABSTRACT OF THE DISCLOSURE A process for the production of a liquid developer for developing an electrostatic latent image which comprises the steps of (1) dispersing in an organic solvent which is miscible with water but is a non-solvent for gelatin, an aqueous solution of gelatin, the concentration of the gelatin being in the range of approximately 1 to 20% by weight, or a solution of gelatin in a mixed solvent of water and an alcohol prepared by incorporating in the aqueous solution of gelatin an alcohol in an amount causing no precipitation of the gelatin to provide a dispersion of gelatin grains where the amount of the organic solvent is at least ten times the amount of the aqueous solution of gelatin or the solution of gelatin in the mixed solvent of water and alcohol to be added thereto, (2) adding to the resultant dispersion of gelatin a solution of a resin which is insoluble in the organic solvent for said gelatin dispersion but soluble in a carrier liquid having an electric resistance of higher than 10 cm. to coprecipitate the gelatin grains and the resin, and (3) adding the precipitates of the gelatin grains and the resin to the carrier liquid mentioned above.

This invention relates to a process for producing an electrophotographic liquid developer to be used for color printing process utilizing electrostatic latent image.

As the method for obtaining a color print of good quality, there prevails most widely a method which combines silver halide emulsion coatings with the color-forming process.

The tanning developing process which similarly utilizes silver halide emulsion and the so-called dye-transfer process which makes use of the gelatin relief obtained consequently have been popularized considerably such as in Technicolor process.

Comparison of the two processes just mentioned reveals that the former process is suitable for processing large quantities of prints, but the images obtained thereby suffer from insufficient durability. In contrast thereto, the latter (transfer process) can provide images of excellent quality having very high durability. This transfer process is rather similar to the art of printing and enjoys an improved payability where a multiplicity of copies are reproduced from one and the same original. However, this process is not suitable for the reproduction of a small number of copies. This is because the net price per one reproduced copy becomes considerably higher in such case. The reason therefore is that the preparation of the gelatin relief to be used as the original plate consumes time and requires skill.

Previously, the inventors discovered that a color printing method by the transfer process capable of forming simply gelatin relief. (See Belgian Pat. No. 724,581). The previous printing method comprises the following steps:

(1) An electrostatic latent image is formed on an insulative layer of an electrophotographic recording material or an electrostatic recording material.

(2) This electrostatic latent image is converted into a visible image by using fine particles of a substance capable of readily absorbing an aqueous medium from an aqueous solution of a water-soluble dye, such as gelatin toner.

(3) The visible image thus formed is fixed by a proper method.

(4) The image of the substance is brought into contact with the aqueous solution of a water-soluble dye to provide the dye to the image by absorption.

(5) An element to be dyed having a surface capable of similarly readily absorbing the said solution of dye is separately prepared and then placed on the dyed imagehaving layer in such a way that the dye-receiving layer thereof is brought into contact with the aforementioned dyed image. At this stage, the dye is transferred onto the dye-receiving layer to provide a final dye image on the element to be dyed. In the production of the liquid developer containing fine gelatin grains fine gelatin toner, which is used for carrying out the color-printing method as mentioned above, it is important to form sufiiciently fine grains of gelatin. It may be possible to crash gelatin grain in dry state, but as the grains or flakes of gelatin are rigid, i.e., hard and sticky, it is fairly diflicult to obtain uniformly fine grains thereof. There is also provided a process wherein an aqueous solution of gelatin is dispersed in a solvent which is a non-solvent for gelatin and the fine gelatin particles are collected from the dispersion. This process suffers such difiiculty that the gelatin grains tend to be aggregated before the collection of the gelatin grains from the dispersion.

Accordingly, an object of the present invention is to provide a process for preparing a liquid developer containing the gelatin toner, which is used for the preparation of gelatin relief for providing color prints by dye-transfer process.

Another object of the present invention is to provide a process for preparing an electrophotographic liquid developer containing as the toner a uniformly 'fine gelatin powder for color printing process which is based on the electrophotographic process as mentioned above.

The aforementioned objects of the present invention can be accomplished by the process of this invention. That is, the liquid developer containing the fine gelatin toner for developing electrostatic latent image is prepared according to the process of this invention by (1) dispersing in an organic solution which is miscible with water but is nonsolvent for gelatin, an aqueous solution of gelatin or a solution of gelatin in a mixed solvent of water and alcohol prepared by incorporating in the aqueous solution of gelatin an alcohol in an amount of causing no precipitation of gelatin to provide a dispersion of gelatin, (2) adding to the resultant dispersion of gelatin a solution of a resin which is insoluble in the organic solvent for said gelatin dispersion but soluble in a carrier liquid having an electric resistance of higher than 10 9 cm. to coprecipitate the fine gelatin grains and the resin, and (3) adding the precipitates of the gelatin grain containing the resin to the carrier liquid mentioned above.

The present invention will be described more in detail in the following.

Step 1 represents a method of finely dispersing gelatin in the polar solvent.

The gelatin to be used in the present invention may be hide gelatin or bone gelatin. From the standpoint of dispersibility, however, it is desirable to use gelatin of such nature that do not have very wide range of gelling point. A refined gelatin or ordinary grade, such as gelatin for photographic grade, is suitable for the objects of this invention. The aqueous solution of gelatin is prepared by using such gelatin. The concentration of gelatin is suitable in the range of from 1 to 20% (by Weight). If the concentration is too low, the amount of gelatin particles obtained is reduced and, as a consequence, the operation efliciency is lowered. If the concentration of gelatin is too high, it becomes impossible to disperse gelatin sufliciently finely. n cooling, the aqueous solution of gelatin gels. Thus, when an alcohol is added to the aqueous solution of gelatin, it is desirable to heat preliminary the aqueous solution of gelatin and alcohol to 30-40 C. As the alcohol, methanol, ethanol, isopropyl alcohol, glycerine, and the like are suitably used. The desirable quantity of the alcohol is from 0.1 to 3 parts by weight based on one part of the aqueous solution of gelatin. Although gelatin is insoluble in alcohol, it is dissolved to a considerable extent in a mixed solvent of water and alcohol. Needless to mention, if alcohol is excessive, gelatin begins to coagulate. Therefore, when alcohol is added to the aqueous solution of gelatin, the addition must be stopped immediately before the solution produces a white haze therein. To one part of the 5% aqueous solution of gelatin maintained at 45 C., for example, there may be added up to one part of methanol. It is likewise possible to obtain a dispersion of gelatin by dispersing an aqueous solution of gelatin directly to an organic solvent which is a non-solvent for gelatin. However, gelatin particles which have been dispersed once tend to aggregate in general. It has been discovered that, when an alcoho] is added to the aqueous solution of gelatin sufiiciently but to such extent that no white turbid or haze is formed in the solution, the gelatin particles less aggregate when the dispersion thereof is formed.

As the suitable organic solvent which is miscible with water but is a non-solvent for gelatin in Step 1, there are ketones and alcohols. Among these, particularly suitable are acetone, methylethyl ketone, and ethanol. Such organic solvent is used in a quantity from to 300 times as large in volume as the aqueous solution of gelatin to be added thereto. The lower limit is determined depending on the dispersibility of gelatin. When the solution of gelatin is added in too large an amount to such organic solvent, the resultant gelatin particles tend to aggregate. The upper limit is determined depending on the workability (efliciency). When the quantity of the solution of gelatin to be added and dispersed is too small, there comes to increase the amount of solvent to be used. although the gelatin particles acquire a higher dispersibility. In this Step 1, a small quantity of vegetable oil may be added to the organic solvent which is miscible with water but is non-solvent for gelatin, for the purpose of improving the dispersibility of gelatin particles. Addition of a surface active agent brings about a desirable result. In dispersing the solution of gelatin, the most desirable result is obtained by using an ultrasonic. dispersion process. Also, a high-speed mixer may be used for the purpose.

Now a description is made of Step 2.

The organic solvent to be used in Step 1 has a miscible nature with water, namely, is a polar solvent. The solvent (carrier liquid) to be used in Step 3 is non-polar in nature. Therefore, the resin to be used in Step 2 may be one which is insoluble in such polar solvent as ketone but is soluble in such non-polar solvent as cyclohexane.

The resins having such property include a polyisobutylene resin, a polybutene resin, a styrene resin, a styrenebutadiene copolymer, a resin-modified phenolformaldehyde resin, and the like.

The resin is added to the dispersion of gelatin in Step 2 as a solution and the solvent for the resin is one miscible with the organic solvent for the dispersion of gelatin particles as Well as the carrier liquid. As such solvents, there are aromatic hydrocarbons such as xylene and toluene, esteric solvents such as butyl acetate, ethyl acetate and methyl acetate, and the like.

In Step 2, the solution of such resin is added toand agitated in the dispersion of gelatin obtained in Step 1, with the result that the resin is insolubilized and precipitated. At this stage, the resin encloses therein the dispersed gelatin particles and, in that state, undergoes precipitation. Thus, the gelatin particles are collected in the state protected by the resin. When the precipitation has reached the state of completion, the precipitate can be isolated by removing the supernatant through decantation. It is also possible to remove the mother liquor more thoroughly by centrifugal separation.

Consequently, the resin to be used in Step 2 serves to prevent individual gelatin particles from being brought into mutual contact. Accordingly, the quantity of the resin thus added is desired to be greater in volume than the gelatin particles to be contained therein. Such resin is dissolved in its entirety into the carrier liquid. Therefore, the maximum quantity of the resin that can be added is determined as what constitutes the limit within which the properties of the electrophotographic liquid developer are retained unspoiled. In many cases, it has been possible to add the resin in the amount up to about 200 times as large as that of gelatin toner.

The gelatin particles which exist as enclosed with the precipitate still retain water. Such water can be removed by washing the precipitate with the aforementioned solvent which is miscible with water. The difliculty with which the re-aggregation of gelatin particles occurs increases with the decrease of water in the particles.

Now Step 3 is explained. The precipitate obtained in Step 2 is added, without being dried to the carrier liquid.

The aforementioned resin which has been precipitated so as to enclose the gelatin particles is soluble in the carrier liquid. The gelatin is, of course, insoluble in the carrier liquid. When the precipitate of resin enclosing therein the gelatin particles is added into the carrier liquid, therefore, the gelatin particles are released into and dispersed in the carrier liquid as the resin is dissolved progressively. At this stage, a part of the resin becomes adsorbed on the surface of the gelatin particles, with the possible consequence that the dispersion of gelatin particles will be stabilized. In Step 3, there is not need for carrying out the operation of dispersion with particular strength. The reason is that the gelatin particles are spontaneously dispersed as the resolution of resin progresses.

The carrier liquid to be used for the present invention is substantially the same as that which is used generally as the electrophotographic liquid developer. To be concrete, there is used a non-polar organic solvent having a high electric resistance. The electric resistance is desired to exceed the level of 10 (2cm. In the case of a 10W electric resistance, there occurs an abrupt destruction in the electrostatic latent image formed on the electrophotographic sensitive layer. Some examples of the solvents which can be used are cyclohexane, kerosene, heptane, hexane, and gasoline.

In the liquid developer according to the invention, the resin remains dissolved in the carrier liquid. Consequently, the developing agent exceeds in the fixing property after the step of development.

To the carrier liquid, there can be added various other soluble components, such as viscosity regulator and nonionic surface active agent.

When the gelatin-containing liquid developer to be obtained according to the present invention is employed, there can be prepared a gelatin relief of excellent quality through the following steps of (1), (2), and (3):

(1) An electrostatic latent image is formed on the insulating layer of-the electrophotographic recording material or electrostatic recording material.

(2) The electrostatic latent image is developed by using the liquid developer incorporating therein the gelatin toner.

(3) The resultant gelatin image is fixed and hardened by a suitable method.

By using the gelatin relief thus obtained, there can be obtained a dye image through the procedure of dyetransfer process, namely, the steps 4 and 5 as follows.

(4) The aqueous solution of a water-soluble dye is brought into contact with the gelatin image so as to allow the dye to be adsorbed by the image.

(5) Separately, there is prepared an element to be dyed which has a surface layer capable of readily adsorbing the said solution of dye. This element is so arranged that the dye deposited layer thereof comes into contact with the aforementioned gelatin image. At this time, the dye transfers itself into the dye-deposited layer, with the consequence that the final color image will be obtained on the element. From one and same gelatin relief, there can be obtained a multiplicity of sheets with dye images by repeating the steps of 4 and 5.

In the case of the electrophotographic sensitive layer to be formed by using zinc oxide, the electrostatic latent image generally has a negative polarity. The gelatin toner according to the present invention has a positive polarity. When the sensitive layer of zinc oxide is combined with the gelatin toner, therefore, there is obtained the attractive development.

In the case of using a selenium-deposited layer as the electrophotographic sensitive layer, the latent image generally has a positive polarity. When such sensitive layer is used in combination with the liquid developer according to the present invention, therefore, there is obtained a repulsive development. Since the gelatin toner is virtually colorless, it is difficult to evaluate the result of development through the inspection of the sheet surface which has undergone the step of development. For this purpose it is convenient to incorporate into the liquid developer in advance a toner composed of a colored pigment in an amount on the order of from Me to based on the gelatin toner. Of course, it is effective to prepare the liquid developer in such a way as to permit a colored pigment or dye to be contained in the gelatin particles.

A further specific description is made of the present invention by referring to preferred embodiments below.

EXAMPLE 1 To 95 g. of distilled water, there was added 5 g. of photographic gelatin. On lapse of 30 minutes, the gelatin became impregnated. A transparent aqueous solution of gelatin was obtained by heating the mixture to 60 C. subsequently.

While ml. of the aqueous solution of gelatin was maintained at 45 C. methanol was added thereto until the solution produced a slight degree of white haze. The total volume of methanol thus added was 11 ml. Then 0.5 ml. of distilled water was added thereto to eliminate the white haze. As a consequence, there was obtained a solution of gelatin in the mixed solvent of water and methanol. The entire volume of this solution was dispersed by means of ultrasonic stirring within a liquid having the following composition.

Acetone 980 Cotton seed oil 20 In this way, there was obtained a dispersion of gelatin which assumed a milky white color.

Into this dispersion, a solution of the following composition was added with agitation.

Ml. Varnish obtained by cooking rosin-modified phenolformaldehyde resin and linseed oil Toluene 36 supernatant was removed through decantation to obtain 200 ml. of the liquid containing therein the precipitate. This liquid was treated with a centrifugal separator to obtain the precipitate of resin containing gelatin particles. The entire volume of this precipitate was added to the mixed solvent having the following composition and the mixture was stirred.

Ml. Toluene 20 Xylene 3.5 Cotton seed oil 6 Non-ionic surface active agent solution 0.3

Ml. Cyclohexane 1600 Kerosene 400 Thus was obtained a liquid developing agent having a light milky white color.

Kerosene was added for the purpose of lowering the speed of vaporization of the liquid developer. The gelatin toner in the liquid developer was found to have a positive electric charge. The liquid developer was placed in a cell designed to determine the electric resistance, and a direct current of v. was applied thereto to test the agent for its electric resistance. Immediately after the application of the voltage, the electric resistance was 7.5 l0 9cm. On lapse of five minutes thence, the resistance was as high as 1.2x 10 9cm. The application of voltage was discontinued and the liquid which had become transparent was removed from the cell. Then the electrodes were inspected. The cathode was found to be covered with a white coat of gelatin particles. On the anode, there was found absolutely no deposition.

Separately, parts by weight of photoconductive zinc oxide and 20 parts (parts given in weight invariably hereinafter) of epoxy ester of dehydrated castor oil fatty acid were mixed with a suitable amount of toluene and obtained a homogeneous coating mixture. To this mixture was added a solution prepared by dissolving 91 part of fluorescein and part of tetrabromophenol blue in a small amount of ethylene glycol monomethylether. This was done to expand the photosensitivity of zinc oxide to the whole range of visible spectrum. After further addition of a suitable amount of toluene, the resultant mixture was spread on a polyethylene terephthalate film having aluminum vacuum-deposited thereon (thickness 90 The dry thickness of the coat was about 8 When the layer was dried sufficiently in a dark place, it functioned excellently as an electrophotographic sensitive material.

This electrophotographic sensitive material was exposed to negative corona discharge in a dark place to have its surface uniformly charged. Subsequently, a color slide intended as the original was loaded on an enlarger, with a red filter placed over the slide. The negatively charged sensitive sheet was then exposed to the light projected through the slide.

The sensitive sheet which had undergone the step of exposure was first wetted wit-h kerosene and immediately dipped into the aforementioned liquid developer. In this case, there was used a stainless steel-made tray as the container, so that the vat could play the role of developing electrode when the surface of latent image approached the tray bottom. After about 90 seconds of dipping, the sensitive material was removed, washed with isoparafiin, and then dried.

Then the sheet which had undergone the step of development was submerged in 1% methanol solution of formaldehyde and left'to stand overnight at room temperature so as to harden the image of gelatin.

Subsequent to the step of solidification, the sensitive material carrying thereon the gelatin image was placed under 40% aqueous solution of acetic acid for 30 seconds. This treatment caused substantially all zinc oxide contained in the sensitive layer to be removed from the layer.

Through the preceding procedure, there was obtained a gelatin relief for use in the cyan print.

In entirely the same manner, another sheet was subjected to exposure to light by using the combination of the same original with a green filter. Through the similar treatment of development, there was obtained a relief for magenta print. A gelatin relief for yellow print was obtained by the same procedure using a blue filter in the combination.

The three gelatin reliefs were submerged for two minutes in the aqueous solutions of Acid Blue 4, Acid Violet 7, and Acid Yellow 23 respectively. At the end of the stated period, they were taken out and then washed in a bath containing acetic acid.

In the meantime, the dye sheet having a gelatin layer was submerged in aluminum sulfate solution to be mordanted. Then, the aforementioned three reliefs were sequentially registered correctly thereon and pressed. This treatment caused the dye absorbed in each toner image to be transferred into the gelatin layer. Thus was obtained a duplicate of extremely high quality. These gelatin reliefs completely withstood about one hundred repeated usages.

The rosin-modified phenolformaldehyde resin contained as dissolved in the liquid developing agent in the present example was insoluble in isoparafiin (Isoper E: made by Esso Standard Oil Co.). For this reason, it served to fix the gelatin toner during the step of washing.

EXAMPLE 2 Selenium was vacuum-deposited to a thickness of 60 on an aluminum plate. The resultant xerographic plate was exposed to positive corona discharge at darkness to have its surface uniformly charged to +350 v. Then, a color negative film intended as the original was loaded on an enlarger, with a red filter placed over the slide. Then the positively charged sensitive sheet was exposed to a light projected through the original.

The exposed xerographic plate was first wetted with kerosene and soaked in the liquid developer described in the first half of Example 1. At this time, a fiat metal plate prepared separately Was positioned close to the surface of the xerographic plate so as to function as the developing electrode.

The space between the xerographic plate and the developing electrode was 0.2 mm. To effect the so-called solarized development, a bias voltage of -180 v. was applied to the xerographic plate. After about 90 seconds of immersion, the xerographic plate was removed from the developing agent, washed with Isoper E (iso-paraffin solvent manufactured by Esso Standard Oil Co.), and then dried.

Subsequently, the xerographic plate which had undergone the step of development was soaked for 20 seconds in 1% methanol solution of formaldehyde and thereafter allowed to stand at room temperature for five hours. By so doing, the gelatin image was hardened. Thus was obtained a gelatin relief to be used for cyan print.

In entirely the same manner, another xerographic plate was subjected to exposure to light by using the combination of the same original with a green filter. Through the similar treatment, there was obtained a gelatin relief for magenta print. Similarly, a gelatin relief for yellow print was obtained by using a blue filter in the combination.

These three gelatin reliefs were separately dyed in the same way as in Example 1.

In the meantime, the dye sheet having a gelatin layer on its surface was subjected to the mordanting treatment, and thereafter registered and pressed against the afore- EXAMPLE 3 There was prepared 2% aqueous solution of gelatin. A 20 m1. portion of this solution was dispersed by means of ultrasonic stirring in the liquid having the following composition.

Acetone 500 Methanol 200 Soybean oil 10 Consequently, there was obtained a dispersion of gelatin with a milky white color.

To this dispersion, there was added the solution of the following composition with agitation.

Rosin-modified phenolformaldehyde resin g 2 Toluene ml 20 Upon addition, a coagulation of resin was observed to occur in the liquid. By following entirely the same procedure as in Example 1, there was prepared a liquid developer. The resultant liquid developer developed the electrostatic latent image of negative polarity formed by the electrophotographic process, whereby there was obtained a gelatin matrix of outstanding quality.

EXAMPLE 4 1n the place of varnish prepared by heating rosinmodified phenolformaldehyde resin and linseed oil in Example 1, there was used Piccolastic D- (styrenic polymer made by Esso Standard Oil Co.).

By following the same procedure as employed in Example 1, there was obtained a liquid developer having excellent dispersibility.

EXAMPLE 5 The procedure of Example 4 was followed, except Pliolite S-SD (styrene-butadiene copolymer made by Goodyear Tire and Rubber Co.) was used in the place of Piccolastic Dl25.

Through the same treatment as in Example 1, there was obtained a liquid developing agent manifesting outstanding dispersibility.

EXAMPLE 6 The procedure of Example 4 was followed, except Poributen (polybutene HV-300 made by Furukawa Chemical Industry Co.) was used inthe place of Piccolastic D-l25.

Through the same treatment as in Example 1, there was obtained a liquid developer having outstanding dispersibility.

EXAMPLE 7 In the procedure of Example 1, the precipitate of resin containing gelatin particles obtained through centrifugal separation was immediately poured into a carrier fluid having the following composition.

Ml. Cyclohexane 1600 Kerosene 350 Cotton seed oil 50 With agitation, the precipitate was readily dissolved and dispersed. Thus was obtained a liquid developing agent showing extremely stable dispersion.

What is claimed is:

1. A process for the production of a liquid developer for developing electrostatic latent image which comprises the steps of:

( 1) dispersing in an organic solvent which is miscible with water but is a non-solvent for gelatin, an aqueous solution of gelatin, the concentration of the gelatin being in the range of approximately 1 to 20% by weight, or a solution of gelatin in a mixed solvent of water and an alcohol prepared by incorporating in the aqueous solution of gelatin an alcohol in an amount causing no precipitation of the gelatin, to provide a dispersion of gelatin grains where the amount of said organic solvent is at least ten times the amount of said aqueous solution of gelatin or said solution of gelatin in the mixed solvent of water and alcohol to be added thereto,

=( 2) adding to the resultant dispersion of gelatin a solution of a resin which is insoluble in the organic solvent for said gelatin dispersion but soluble in a carrier liquid having an electric resistance of higher than 10 cm, to coprecipitate the gelatin grains and the resin, and

(3) adding the coprecipitates of the gelatin grains and the resin to the carrier liquid mentioned above, the gelatin being insoluble in said carrier liquid.

2. The process as claimed in claim 1, wherein said organic solvent which is miscible with water but is a nonsolvent for gelatin is acetone, methylethylketone, or etha- 1101.

3. The process as claimed in claim 1, wherein said organic solvent which is miscible with water but is a nonsolvent for gelatin is used in a quantity from to 300 times as large in volume as said aqueous solution of gelatin or said solution of gelatin in the mixed solvent of water and alcohol to be added thereto.

4. The process as claimed in claim 1, wherein said resin used in step 2 described in claim 1, is polyisobutylene resin, polybutene resin, styrene resin, styrene-butadiene copolymer or rosin-modified phenolformaldehyde resin.

5. The process as claimed in claim 1, wherein said carrier liquid is cyclohexane, kerosene, heptane, hexane, or gasoline.

6. The process as in claim 1 wherein said organic solvent is polar and said carrier liquid is non-polar.

7. The process as in claim 1 where the amount of said alcohol is from 0.1 to 3 parts by weight based on one part of said aqueous solution of gelatin.

8. The process as in claim 1 where the amount of resin added is up to about 200 times the amount of the gelatin.

9. The process as in claim 1 wherein said resin is synthetic.

References Cited UNITED STATES PATENTS 3,137,630 6/1964 Hecker et al. 269-117 2,893,867 7/1959 Dawson et al. 9698 2,698,797 1/ 1955 Godowsky et al. 9698 2,527,268 10/1950 Hart et al. 9697 2,490,749 12/1949 Fierke et al. 9698 2,297,691 10/1942 Carlson 961 2,197,843 4/1940 Leuwen 106135 2,105,413 1/1938 Dewsbury 106-435 1,854,061 4/1932 Pigache 196-135 94,076 8/1869 Coombs 106-125 2,284,877 6/1942 Martinez 9694 GEORGE F. LESMES, Primary Examiner J. P. BRAMMER, Assistant Examiner US. Cl. X.R.

96-l.2; 106-125, 117--37 LY; 2608, 117