Classifications

• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
  • G03G9/00—Developers
  • G03G9/08—Developers with toner particles
  • G03G9/12—Developers with toner particles in liquid developer mixtures
  • G03G9/13—Developers with toner particles in liquid developer mixtures characterised by polymer components
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
  • G03G13/00—Electrographic processes using a charge pattern
  • G03G13/26—Electrographic processes using a charge pattern for the production of printing plates for non-xerographic printing processes
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
  • G03G8/00—Layers covering the final reproduction, e.g. for protecting, for writing thereon
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
  • G03G9/00—Developers
  • G03G9/08—Developers with toner particles
  • G03G9/12—Developers with toner particles in liquid developer mixtures

Definitions

• 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
• This invention relates to a process for producing an electrophotographic liquid developer to be used for color printing process utilizing electrostatic latent image.
• 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.
• the previous printing method comprises the following steps:
• An electrostatic latent image is formed on an insulative layer of an electrophotographic recording material or an electrostatic recording material.
• 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.
• 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.
• 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.
• 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.
• 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 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.
• 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.
• an alcohol when added to the aqueous solution of gelatin, it is desirable to heat preliminary the aqueous solution of gelatin and alcohol to 30-40 C.
• 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.
• 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.
• a dispersion of gelatin by dispersing an aqueous solution of gelatin directly to an organic solvent which is a non-solvent for gelatin.
• 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.
• 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.
• the upper limit is determined depending on the workability (efliciency).
• 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.
• 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.
• Step 2 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.
• solvents there are aromatic hydrocarbons such as xylene and toluene, esteric solvents such as butyl acetate, ethyl acetate and methyl acetate, and the like.
• 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.
• the resin encloses therein the dispersed gelatin particles and, in that state, undergoes precipitation.
• the gelatin particles are collected in the state protected by the resin.
• 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.
• 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.
• 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.
• 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.
• 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.
• 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.
• 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.
• the resin remains dissolved in the carrier liquid. Consequently, the developing agent exceeds in the fixing property after the step of development.
• viscosity regulator and nonionic surface active agent.
• An electrostatic latent image is formed on the insulating layer of-the electrophotographic recording material or electrostatic recording material.
• 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.
• the electrostatic latent image 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.
• the latent image In the case of using a selenium-deposited layer as the electrophotographic sensitive layer, the latent image generally has a positive polarity.
• the sensitive layer When such sensitive layer is used in combination with the liquid developer according to the present invention, therefore, there is obtained a repulsive development.
• the gelatin toner 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.
• 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.
• the electric resistance was 7.5 l0 9cm.
• 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.
• 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.
• 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.
• the sensitive material was removed, washed with isoparafiin, and then dried.
• 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.
• 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.
• 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.
• 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.
• a bias voltage of -180 v. was applied to the xerographic plate.
• 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.
• 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.
• 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.).
• a process for the production of a liquid developer for developing electrostatic latent image which comprises the steps of:
• step 2 described in claim 1 is polyisobutylene resin, polybutene resin, styrene resin, styrene-butadiene copolymer or rosin-modified phenolformaldehyde resin.

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• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Liquid Developers In Electrophotography (AREA)
• Compositions Of Macromolecular Compounds (AREA)
• Photoreceptors In Electrophotography (AREA)

Applications Claiming Priority (1)

Publications (1)

Family

ID=11679593

Family Applications (1)

Country Status (7)

Cited By (4)

• 1970
  • 1970-01-27 CA CA073144A patent/CA924165A/en not_active Expired
  • 1970-01-30 FR FR7003324A patent/FR2031283A5/fr not_active Expired
  • 1970-01-30 NL NL7001351A patent/NL7001351A/xx unknown
  • 1970-02-03 GB GB5133/70A patent/GB1255762A/en not_active Expired
  • 1970-02-03 DE DE2004817A patent/DE2004817C3/de not_active Expired
  • 1970-02-03 US US8432A patent/US3682825A/en not_active Expired - Lifetime
  • 1970-02-03 BE BE745390D patent/BE745390A/xx not_active IP Right Cessation

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