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
  • G03G9/125—Developers with toner particles in liquid developer mixtures characterised by the liquid
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J2/00—Processes or devices for granulating materials, e.g. fertilisers in general; Rendering particulate materials free flowing in general, e.g. making them hydrophobic
  • B01J2/02—Processes or devices for granulating materials, e.g. fertilisers in general; Rendering particulate materials free flowing in general, e.g. making them hydrophobic by dividing the liquid material into drops, e.g. by spraying, and solidifying the drops
  • B01J2/06—Processes or devices for granulating materials, e.g. fertilisers in general; Rendering particulate materials free flowing in general, e.g. making them hydrophobic by dividing the liquid material into drops, e.g. by spraying, and solidifying the drops in a liquid medium
  • B01J2/08—Gelation of a colloidal solution
• • 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
  • G03G9/13—Developers with toner particles in liquid developer mixtures characterised by polymer components

Definitions

• ABSTRACT A process for producing a liquid developer for developing electrostatic latent images which comprises (1) adding to an aqueous solution of gelatin, the concentration of the gelatin being in the range of approximately 1 to 20 percent by weight, an alcohol in an amount less than that of causing the precipitation of gelatin to provide a solution of gelatin in a water-alcohol mixed solvent, (2) dispersing the solution thus prepared in an organic solvent which is miscible with water but is a non-solvent for gelatin to form a dispersion of fine gelatin particles where the amount of said organic solvent is at least 10 times the amount of the mixed gelatin solution of water and alcohol and recovering the tine gelatin particles from the dispersion, and (3) dispersing the fine gelatin particles thus recovered in a carrier having an electric resistance of higher than 1010"Qcm.
• This invention relates to a process for producing liquid developer containing gelatin toner adapted for use in developing electrostatic latent image obtained in electrophotographic or electrostatic recording method, and particularly to a process for producing a liquid developer adapted for producing gelatin relief to be employed for color printing process utilizing electrostatic latent image.
• Multicolor print of good quality is most widely obtained by silver halide coatings combined with color forming development process.
• socalled dye transfer or dye imbibition process which utilizes gelatin relief resulting from tanning development of silver halide coatings is also commercially known in the name of Technicolor process, etc.
• the dye transfer process is capable to providing images with extremely good lightstability and long life.
• This process having a nature resembling printing method, becomes economical in case of obtaining many copies from one original but is expensive if only limited number of copies is required, because the preparation of gelatin relief requires time and skill.
• the inventor already proposed a color printing process utilizing dye transfer process by means of easily obtainable gelatin relief, which consists of following steps, (cf., Belgian Pat. No. 724,581):
• gelatin toner In the preparation of liquid developer containing gelatin powder (gelatin toner) for use in color printing process as explained above, the most difficult step is pulverization of gelatin into sufficiently fine state.
• an object of this invention is to provide an improved process for producing liquid developer containing gelatin toner adapted for use in preparing gelatin relief to be utilized in dye transfer process to obtain color print.
• Another object of this invention is to provide a process for producing liquid developer for electrophotography containing uniform and fine gelatin particles as toner and adapted for use in electrophotographic color printing process as explained above.
• the present inventor found to be able to achieve a further improved result by inserting, between the steps (2) and (3) of the aforesaid process for producing liquid developer, a step of washing the obtained gelatin powder with a water-miscible organic solvent in which gelatin is insoluble thereby removing moisture containing in said powder.
• both hide and bone gelatin can be satisfactorily employed for this invention.
• the range of gelling point should not be excessively wide in order to obtain sufficient dispersion.
• Purified ordinary photographic gelatin is suitable for use in this invention.
• the concentration of gelatin should be between 1 and 20 wt.%, since excessively low will involve the use of large amount of water in above-mentioned step 2 therefore leading to lowering of yield of gelatin with respect to the amount of employed organic solvent, and will also result in the incorporation of large amount of water in the obtained particles of gelatin thereby lowering the efiiciency of additional washing step mentioned above, whereas an excessively high concentration will make it impossible to add a large amount of alcohol in step 1, thus leading to insufficient dispersion and tendency of causing coagulation.
• Alcohol to be employed for this purpose may be methanol, ethanol, isopropyl alcohol or glycerine.
• the amount of alcohol to be added should desirably be 0.1 to 3 parts by volume with respect to 1 part by volume of gelatin solution.
• Gelatin is insoluble in alcohol, but considerably soluble in water-alcohol mixture. For example, about 1 part of methanol can be added without causing precipitation to 1 part of 5 wt.% aqueous solution of gelatin kept at 45C.
• the water-miscible organic solvent which is nonsolvent for gelatin in the step 2 mentioned above be ketones or alcohols may be used, and acetone, methylethylketone or ethanol is preferable. These organic solvents should be used in a -300 times by volume with respect to that of gelatin solution (dissolved in water-alcohol).
• the lower limit of this amount is determined by the dispersibility of gelatin since the obtained gelatin particles are apt to aggregate when a too much amount of gelatin solution is used, whereas the upper limit is determined by working efficiency since it is uneconomical because of consumption of large quantity of solution, although the gelatin particles can be sufficiently dispersed in this case.
• step 2 in order to improve dispersibility of gelatin particles, it is possible to add a small amount of vegetable oil to the water-miscible organic solvent which is non-solvent for gelatin. Also a preferable result can be obtained by adding a surface active agent to said organic solvent.
• the use of ultrasonic stirring is most preferably but a high-speed mixer may be used.
• the dispersion of gelatin particles in an organic solvent obtained in step 2 contains a considerable amount of water derived from the aqueous solution of gelatin, a part of which is in the organic solvent phase and a part of which is present in the gelatin particles.
• the water present in said dispersion should be removed since the presence of water in liquid developer for electrophotography is not preferable.
• gelatin particles in the dispersion are further washed with the aforesaid organic solvent.
• the gelatin particles present in the dispersion are recovered by filtration, floccuration, centrifugal separation, etc., and then redisperse in the fresh organic solvent mentioned above.
• the step which may be repeated if necessary, the content of water present in gelatin particles is reduced and simultaneously the gelatin particles shrink to be finer, which results in reducing the tendency of aggromation.
• gelatin particles may be dispersed after drying, much more stable dispersion can be obtained by adding gelatin particles in wet (or paste) state to said organic solvent.
• the carrier liquid for use in this invention may be similar to that employed in ordinary electrophotographic liquid developer, namely may be a non-polar organic solvent having a high electric resistance, preferably higher than l0Qcm, since low electric resistance will give rise to the destruction of electrostatic latent image formed on electrophotographic photosensitive layer.
• the examples of the carrier liquid are cyclohexane, kerosene, gasoline, isooctane, heptane, hexane and chlorofluorohydrocarbons.
• the carrier liquid may contain various components soluble therein, such as nonionic surface active agent, dispersing agent or resin for fixing etc.
• the amount of gelatin to be added (concentration of toner) to said carrier liquid should preferably be 0.001-5 percent by weight with respect to said carrier liquid since electrostatic latent image on photosensitive layer cannot effectively be developed when said concentration is excessively low, and an excessively high concentration will result in the formation of fogging. Besides there are instances the stability of dispersion is deteriorated with the increase of said concentration.
• gelatin relief can be prepared by the following steps:
• V keeping a surface capable of absorbing said solution of a separate image-receiving material into face-to-face contact with said gelatin image thereby, transferring said absorbed dye onto said image-receiving material to form final image.
• the steps IV and V represent the procedure of obtaining dye image by means of obtained gelatin matrix, and thus plural copies of image-receiving sheets having dye image can be obtained by repeating the steps IV and V.
• electrophotographic photosensitive layer consisting of zinc oxide which generally provides electrostatically negative latent image
• the development is carried out by electrostatic attraction since charge of the gelatin toner of this invention is electrostatically positive.
• selenium which generally provides electrostatically positive latent image is used as photosensitive layer
• the development by liquid developer of this invention is carried out by electrostatic repulsion.
• gelatin toner obtained according to this invention is almost colorless, it is very difiicult to judge the result of development by inspecting visually the developed surface. Consequently it is advantageous to add toner consisting of colored pigment to the liquid developer in a 1/5-l/l00 amount of gelatin toner. It is also advantageous to prepare liquid developer from gelatin particles containing colored pigment or dye.
• Example 1 5 g. of photographic gelatin added to g. of distilled water. After 30 minutes, the gelatin was sufficiently swelled. Thereafter, the mixture was warmed to 60C to provide a transparent aqueous solution of gelatin. While keeping 10 ml. of thus obtained solution at 45C, methanol was added gradually until very slight white turbidity was formed. The amount of methanol added was ll ml. Then when 0.5 ml. of distilled water was added, the white turbid disappeared. Thus, obtained solution of gelatin in water-methanol was dispersed in l l.
• liquid developer of milk-white color soybean oil was employed as dispersing agent. Rosin-modified phenol-formaldehyde resin was used as fixing agent. This agent is soluble in carrier liquid but is insolubilized in rinsing bath (for instance, isoparaffin rinsing bath) used after development thereby fixing gelatin toner. Kerosene was added in order to control the evaporation of liquid developer. Gelatin toner contained in this liquid developer was found to be provided with electrostatically positive charge.
• Said material was subjected to negative corona discharge at darkness thereby forming uniform electrostatic charge thereon and then subjected to imagewise projection of a color slide superposed with a red filter.
• the photosensitive sheet was wetted with kerosene and immediately immersed into the liquid developer explained above.
• the surface holding latent image may face to the bottom of stainless steel container containing said liquid developer in order to utilize said container as the developing electrode.
• gelatin image was then hardened by dipping said sheet in 1 percent methanol solution of formaldehyde lowed by standing overnight at room temperature.
• a separate sheet material was subjected to imagewise projection through the same color slide superposed with a green filter and processed in the same manner as explained above thereby to obtain a gelatin relief for magenta color printing.
• the matrix for yellow color printing was prepared by using a blue filter.
• a dye-receiving sheet provided with a gelatin layer was immersed in aqueous solution of aluminum sulfate and then brought into contact successively in register with said three gelatin reliefs. Dyes absorbed in toner images were thus transferred to said gelatin layer to form a color reproduction of extremely high quality. Said gelatin reliefs were found to be capable of providing at least times run.
• Example 2 A selenium layer of 60p, thick was provided on an aluminum plate by vacuum deposition.
• the xerographic plate was wetted with kerosene and immersed into the liquid-developer of example 1.
• a flat metal plate was held at a distance of 0.2 mm to the surface of said xerographic plate as a developing electrode.
• So-called reversal development was carried out by applying a bias potential of V. to the xerographic plate.
• the plate was taken out, washed with Isoper E (lsoparaffin solvent: Esso Standard Oil Co.) and dried.
• the obtained gelatin image was hardened by dipping said plate for 20 seconds in 1 percent methanol solution of formaldehyde followed by standing for 5 hours at room temperature, thereby to complete a gelatin relief for cyan color printing.
• a gelatin relief for magenta color printing was prepared similarly on a separate xerographic plate by means of exposure through the same color slide and a green filter. Also the gelatin relief for yellow color printing was prepared with a blue filter.
• An image-receiving sheet having a gelatin layer was treated as in Example 1, and brought into contact in register successively with said three gelatin reliefs. Dyed obtained in toner images were thus transferred to said gelatin layer to form a positive color reproduction of extremely high quality. Said matrixes were found to be capable of providing at least 25 copies.
• the xerographic plates after use were washed successively with warm alkaline aqueous solution acetonetoluene mixture and toluene, and dried. Thus the plates were ready for use again in another cycle.
• Example 3 Solution of gelatin in mixed solvent was prepared according to the procedure of Example 1, and employing ethanol instead of methanol. The amount of ethanol added was 10 ml.
• Gelatin relief could be prepared by thus obtained similar developer and same procedure as described in Example 1.
• Example 4 Methylethyl ketone was employed instead of acetone in the procedure of Example 1. Gelatin relief could also be prepared by thus obtained similar developer and same procedure as described in Example 1.
• Example 5 A mixture of 20 ml. of soybean oil and 980 ml. of acetone was employed instead of acetone in Example 1.
• the obtained liquid developer contained gelatin particles finer than those obtainable in Example 1.
• Example 6 Solution of gelatin in mixed solvent was prepared by employing 10 ml. of ethanol instead of methanol in Example 1. Also methylethylketone was used as dispersing agent instead of acetone, thereby to provide a liquid developer similar to that obtainable in Example 1.
• a process for producing a liquid developer for developing electrostatic latent images which comprises:
• said carrier liquid is cyclohexane, kerosene, gasoline, isooctane, heptane, hexane, or a chlorofluorohydrocarbon.
• a process for producing a liquid developer for developing electrostatic latent images which comprises:
• said carrier liquid is cyclohexane, kerosene, gasoline, isooctane, heptane, hexane, or a chlorofluorohydrocarbon.

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• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Chemical & Material Sciences (AREA)
• Dispersion Chemistry (AREA)
• Organic Chemistry (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Liquid Developers In Electrophotography (AREA)
• Wet Developing In Electrophotography (AREA)

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Citations (9)

• 1970
  • 1970-02-02 NL NL7001443A patent/NL7001443A/xx unknown
  • 1970-02-03 CA CA073763A patent/CA924166A/en not_active Expired
  • 1970-02-03 GB GB5136/70A patent/GB1255763A/en not_active Expired
  • 1970-02-05 US US00009042A patent/US3718593A/en not_active Expired - Lifetime
  • 1970-02-05 BE BE745535D patent/BE745535A/xx unknown
  • 1970-02-05 FR FR7004034A patent/FR2037067A1/fr not_active Withdrawn

Patent Citations (9)

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