JPH0433027B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD The present invention relates to a liquid developer for electrophotography and a method for manufacturing a printing plate using this developer, and particularly to a liquid developer used when producing a lithographic printing plate by an electrophotographic method. This invention relates to a toner image that improves the printing durability and printability of the toner image and prevents the image area from being eroded by an etching solution that dissolves the non-image area. Prior art It has also been done to create a lithographic printing plate with good resolution by exposing a photosensitive resin layer using a silver salt photosensitive material using a photoengraving method, but printing plates are also created by directly photographing the original. That saves labor,
This is done from the perspective of resource conservation. By this method, for example, to create a lithographic printing plate, a photoconductive layer previously formed on the support is charged by a corona charging device, and then exposed to light according to the brightness of the original to create an electrostatic charge depending on the presence or absence of charge. A latent layer is formed and then developed with a developer to form an image area and a non-image area. Then, this image area may be transferred and fixed onto another support or printing original plate to form a printing plate, but the non-image area of the photoconductive layer may be hydrophilized (desensitized) or this non-image area may be It is also possible to prepare a lithographic printing plate by dissolving and removing the etching portion with an etching solution. At this time, a powder developer can be used, but since the particles are relatively large and the resolution is not good, a liquid developer is used. This liquid developer is made by dispersing so-called toner, which forms the image area, in a solvent and supporting it. During development, the charged toner is attached to the latent image by electrophoresis, and then it is fixed. It is. To this end, the toner is composed of a chargeable substance such as pigment or dye particles that causes electrophoresis, and a resin that is adsorbed to the particles and moves together with the particles. In this case, if the toner particles become large, there will be a problem in terms of resolution as mentioned above, so in order to prevent this from becoming large, the toner needs to have dispersion stability in the solvent, that is, the carrier liquid, and also to form the image area. It must have good adhesion to lipophilic printing ink, that is, good ink receptivity, and must also have printing durability as a printing plate. Further, when the non-image area is to be dissolved and removed by an etching solution, the material must not dissolve or swell in an aqueous etching solution such as a commonly used aqueous alkaline solution. In order to meet this requirement, it is particularly important to consider the resin components. JP 55-3696, JP 55-10195, JP 52-125333, JP 48-49445
The publication describes a liquid developer for electrophotography in which a toner whose main components are a pigment or dye and a non-aqueous thermoplastic resin is dispersed in a carrier liquid.
It has been shown that waxes and polyethylenes can be added in a range of 0.4 to 40% by weight. However, the main purpose of these methods is to improve the dispersion stability of pigment or dye particles in the developer state, and the toner image produced by this developer has insufficient fixing properties and is not suitable for printing plates. When used in
Mechanical strength to ensure printing durability and printing ink receptivity are insufficient. In addition, when a toner image is used as a resist and a non-image area is eluted with an aqueous etching liquid, it is inevitable that the image area will be eroded by the etching liquid and will be partially eluted or swell. As described above, conventional liquid developers still have problems in not only providing the stability of the developer components but also satisfying the above-mentioned properties as a printing plate and resistance to etching solutions. Therefore, the present invention proposed a liquid developer containing wax and/or polyolefin in an amount of 45 to 95% by weight of the resin component in Japanese Patent Application No. 113644/1982. However, as a result of intensive research, we have found that even if such a liquid developer is used, printing plates made without heat fixing the toner image may not always have sufficient resistance to etching solutions. were discovered, and improvements were desired. Purpose of the Invention The first object of the present invention is to apply an etching solution to the non-image areas of a printing original plate developed using a liquid developer for electrophotography without heat-fixing the developer and without eroding the toner image. An object of the present invention is to provide a method for producing a printing plate that can be removed by elution. A second object of the present invention is to provide a printing plate obtained by the above manufacturing method, which has excellent printing power and excellent printability such as ink receptivity to printing ink. be. Structure of the Invention In order to achieve the above object, the present invention forms a toner image area by electrophotography using a liquid developer on a printing original plate having a photoconductive layer on a conductive support. In a printing plate production method in which a printing plate is created by removing a non-image area, which is an area where no image is formed, a toner whose main components are pigment and/or dye particles and a resin is added to the carrier liquid. The resin contains (a) 5 to 55% by weight of a polymer compound consisting of a monomer component soluble in the carrier liquid and a monomer component poorly soluble or insoluble in the carrier liquid, and (b) an average molecular weight of less than 3000. polyolefin compounds
The present invention provides a method for producing a printing plate, characterized in that a liquid developer containing 45 to 95% by weight is used. Next, the present invention will be explained in detail. The polymer compound (a) used in the present invention maintains the dispersion stability of the pigment or dye particles or polyolefin compound particles in the carrier liquid, and also constitutes a component of the toner image area. , contains a monomer component soluble in the lipophilic carrier liquid described below. This polymeric compound is soluble in the carrier liquid. Therefore, the pigment or dye particles are dispersed in the carrier liquid so as to be surrounded by the polymer compound, so that aggregation of the pigment or dye particles is prevented and their dispersion stability is maintained. Such polymer compounds include linear polymer compounds, graft polymer compounds, and mixtures thereof. (a) Examples of linear polymer compounds Examples of monomer components soluble in the carrier liquid include monomers represented by the following general formula. General formula [] Here, R is H, CH ₃ , C ₂ H ₅ and A is
COOCnH ₂ n+ ₁ , OCnH ₂ n+ ₁ (n is 6 to 20). Specifically, stearyl, lauryl, 2-ethylhexyl or hexyl ester of acrylic acid or methacrylic acid, cetyl or octyl ester of methacrylic acid, or stearyl vinyl ether,
Examples include lauryl vinyl ether. Further, in order to improve the dispersion stability of the toner, a copolymer of these monomers and a monomer that is sparingly soluble or insoluble in the carrier liquid may be used. Examples of monomer components that are poorly soluble or insoluble in the carrier liquid include the following ethylenically unsaturated monomers. Alkyl acrylate or alkyl methacrylate Specific examples include ethyl acrylate, methyl acrylate, butyl acrylate, butyl methacrylate, and the like. Specific examples of the carboxyl group-containing monomer include acrylic acid, methacrylic acid, crotonic acid, fumaric acid, itaconic acid, and carboxystyrene. Alcoholic hydroxyl group-containing monomer Specifically, β-hydroxymethyl acrylate, β-hydroxyethyl methacrylate, β-
Examples include hydroxypropyl methacrylate. N-containing monomer with the following general formula General formula [] General formula [] In the above general formula [], R is H, CH ₃ , l
is an integer of 1 to 4, m is an integer of 1 to 4, in the general formula [], R is H or CH ₃ , B is -C ₆ H ₄
(phenylene) or naphthylene, l and m are each 0 or 1, and n is an integer of 0 to 4. Specifically, those that fall under the general formula [] are:
Those corresponding to the general formula [], such as dimethylaminoethyl methacrylate and diethylaminoethyl methacrylate, include acrylamide, aminostyrene, dimethylaminostyrene, carbamoystyrene, N,N-dimethylcarbamoylstyrene, and the like. Sulfonic acid-containing monomer represented by the following general formula [] Here, R is H, CH ₃ and D is (CH ₂ SO ₃ ) _1-2 M (SO ₃ ) _1-2 M Here, M represents an alkali metal, NH ₄ or an alkaline earth metal. Other monomers Specific examples include glycidyl acrylate, glycidyl methacrylate, acrylonitrile, styrene, vinyltoluene, vinyl acetate, chlorostyrene, hydroxystyrene, divinylbenzene, ethylene glycol dimethacrylate, and the like. One or more of the above-mentioned monomers soluble in the carrier liquid and, if necessary, monomers sparingly soluble or insoluble in the carrier liquid, are used from each group. The copolymer ratio of monomers that are sparingly soluble or insoluble in this carrier liquid is preferably 0 to 30%. (b) In the case of a graft polymer compound For example, a graft polymer compound manufactured from the following three steps a, b, and c can be mentioned. a Step of copolymerizing the monomer represented by the above general formula [] and an unsaturated carboxylic acid or glycidyl (meth)acrylate. b When the copolymer of a above is used as glycidyl (meth)acrylate when the constituent monomer of this copolymer contains an unsaturated carboxylic acid, and when this polymer contains glycidyl (meth)acrylate, it is used as an unsaturated carboxylic acid. The process of esterifying each with an acid. c The esterified product obtained in step b above is mixed with polymerizable vinyl monomers of the monomer group that is sparingly soluble or insoluble in the carrier liquid, such as acrylic acid, methacrylic acid, or lower alkyl esters thereof, styrene, methylstyrene, vinyltoluene, and vinyl acetate. The process of grafting. These graft polymer compounds may be used alone or in combination. The above (a) and (b) can be used alone,
It can also be used in combination. These polymer compounds have a molecular weight of 10,000~
300,000 is preferable in terms of alkali resistance when etched with an alkaline etching solution and dispersion stability of toner particles. Particularly preferred molecular weight ranges are from 30,000 to
The range is 150000. The polyolefin compound (b) of the resin component of the toner of the present invention constitutes a component of the toner image area, and since it is contained in the toner resin in an amount of 45 to 95% by weight, it is particularly effective against aqueous etching liquids. This improves durability and also improves printing durability when used as a printing plate. The polyolefin compound used in the present invention is
The average molecular weight is less than 3000, preferably 500 or more. When the molecular weight is 3000 or more, when heat fixing is not performed after forming a toner image,
Resistance to etching liquid may become insufficient, and image areas may be eluted and removed, and printing durability and ink receptivity may become insufficient. Note that the average molecular weight here includes a number average molecular weight. The polyolefin compound used in the present invention contains one or more of polyethylene, polypropylene, ethylene copolymer, and propylene copolymer. Examples of monomers copolymerizable with ethylene and propylene used in the ethylene copolymer and propylene copolymer include acrylic acid, methyl acrylate, ethyl acrylate, vinyl acetate, vinyl chloride, and tetrafluoroethylene. Further, halogenated polyolefin, which is obtained by halogenating polyethylene or polypropylene under special conditions, can also be used. Among these, polyethylene is particularly preferred. Moreover, it is also preferable to use other polyolefin compounds together with polyethylene. Note that the above compounds may be used in combination. Regarding the polymer compound (a) and the polyolefin compound (b), the polymer compound (a) is 5 to 55% by weight and the polyolefin compound (b) is 45 to 95% by weight based on the total resin content. % mixed. If the former is too large and the latter is too small, the toner image area will not have resistance to the aqueous etching solution, and the printing plate will have insufficient mechanical properties and ink receptivity for printing durability. Moreover, if the former becomes too small and the latter becomes too large, the dispersion stability of the pigment or dye used in the developer cannot be maintained, leading to aggregation of these particles. The pigments or dyes used in the present invention are mainly used to impart charges for electrophoresis to electrostatic images, and include carbon black, oil blue, alkali blue, phthalocyanine blue, phthalocyanine green, spirit black, and oil bio. Lettu, benzidine yellow, methyl orange,
Examples include brilliant carmine, fast-stretched, and methyl violet. These may be used alone or in combination of two or more. These pigments or dyes are added to the resin component of the toner component.
10 to 200 parts by weight are used per 100 parts by weight. The carrier liquid used in the present invention serves as a dispersion medium that disperses and holds the toner in a charged state, and has high insulating properties and a low dielectric constant. Such substances include petroleum-based aliphatic hydrocarbons or their halogen derivatives. Examples of such aliphatic hydrocarbons include n-hexane, n-pentane, isooctane, and isododecane, and commercially available products include isoparaffins Isopar H, Isopar G, Isopar L, and Isopar E manufactured by Exxon. , or Ciel Sol-71 manufactured by Ciel Sekiyu. Furthermore, examples of halogen derivatives of aliphatic hydrocarbons include carbon tetrachloride and perfluoroethylene. The toner concentration in the carrier liquid is preferably 0.05% to 10%. In addition,
The above materials used as carrier liquid have a dielectric constant of 3.
The following are those with a solubility parameter of 8.5 or less. Additives such as a charge control agent and an image running prevention agent can be added to the liquid developer of the present invention, if necessary. Such charge control agents include lecithin, naphthenic acid metal salts, alkylbenzene sulfonates, dialkylnaphthalene sulfonates, mono- or dialkyl sulfosuccinates, dialkyl phosphate salts, linseed oil, soybean oil, natural or synthetic resins. etc. In addition, examples of the image running prevention agent include low molecular weight fluorine-containing resins, low molecular weight silicones, low molecular weight polystyrenes, rosin esters, petroleum resins, sucarose acetate isobutyrate, and the like. In order to produce the liquid developer of the present invention, the above-mentioned polymer compound (a), the polyolefin compound (b), a pigment or dye, and the above-mentioned one as necessary are added to the above-mentioned carrier liquid having high insulating property and low dielectric constant. Additives are added and mixed using a ball mill, sand mill, colloid mill, ultrasonic dispersion method, or the like. In this way, for example, pigment or dye particles and polyolefin compound particles are made fine and become dispersoids, which are added to the above (a).
toner particles are formed by adhering the polymer compound by, for example, adsorption or the like. In such toner particles, the above-mentioned dispersoid is charged and has an electric charge due to the process of micronization, etc., and the particles with this charge are the above-mentioned (a).
It is dispersed in a carrier liquid so as to be surrounded by a polymer compound. At this time, since this polymer compound envelops the pigment or dye particles, its dispersion stability can be maintained well. In the above explanation, a polyolefin compound having a molecular weight of less than 3000 is mixed with the polymer compound (a) above, but it may be added during synthesis of the polymer compound to improve its dispersion efficiency. When using the liquid developer of the present invention produced in this way, a printing original plate prepared in advance and having a photoconductive layer on a support is charged and exposed to light by a normal electrophotographic method. The original printing plate on which an electrostatic image has been formed is immersed in this liquid developer according to the electrophotographic development method. The photoconductive layer is a layer containing a photoconductor, and one or more of an inorganic photoconductor, an organic photoconductor, and a photoconductive organic pigment are used as the photoconductor. . In the above-mentioned plate-making process, a xenon lamp, a halogen lamp, a fluorescent lamp, a tungsten lamp, a semiconductor laser, Ar ion, He-Ne laser light, or the like is used as an exposure light source. In this way, the charged toner particles adhere to the image area of the printing original plate by electrophoresis. When the original printing plate is then taken out, the electrostatic image is turned into a visible image by the toner. After fixing this visible image, the non-image area is etched to form a printing plate. To carry out the above fixing, the carrier liquid remaining on the photoconductive layer is removed using a squeeze roller, air at room temperature, or warm air, and the photoconductive layer is
The polymer compound (b), the polyolefin compound (b), and the pigment or dye used remain, and the polymer compound (a) mainly serves as a binder to fix other components to the photoconductive layer. At this time, since the particles of the polyolefin compound are dispersed in the carrier liquid in a swollen state, the particles fuse together as the carrier liquid evaporates during fixing, forming a strong film. In this state, when the toner image is transferred to another support as described above, the transfer is performed well. In the present invention, simply removing the carrier liquid as described above is enough to effect fixing, but there is no particular disadvantage in applying pressure or heating at the same time as or after the removal of the carrier liquid. Once the toner particles are adhered or fused to the photoconductive layer in this way, even if the non-image areas are subsequently etched with an etching solvent, especially an aqueous etching solvent, the etching solvent, especially water, will remove much of the resin component of the toner. Since the polyolefin compound (b) is hydrophobic and is repelled, this etching solution does not penetrate into the toner image area, and erosion of this image area is prevented. At this time, if a polyolefin compound with an average molecular weight of 3000 or more is used, the above-mentioned fusion will be difficult to occur at room temperature, the film-forming property and hydrophobicity will be insufficient, and the penetration of the etching solution will not be sufficiently prevented. Sometimes. In this way, a printing plate is created in which most of the photoconductive layer and toner particles remain and the reproduction of the original image is good, and this toner image area is not easily swollen or softened by the etching solution, so it can be used in the printing plate. Improve ink receptivity, printing durability, etc. when printing. When using this printing plate, since the polyolefin compound (b) above is contained in a large amount in the toner resin component, normally hydrophobic, that is, lipophilic printing ink adheres well to the toner image area and has good ink receptivity. It's going to be a good thing. In addition, this polyolefin compound has a function as a slip agent when it is rubbed against a paper that comes into contact with it during printing, and the above-mentioned fixation is performed together with the contribution of this polyolefin compound to adhesiveness, so that each component of the toner particles can be bonded to each other. Since the adhesion and the adhesion to the image-forming surface are strong, the mechanical strength of the toner image area is increased and the printing durability is also improved. Effects of the Invention The present invention provides pigments and/or dyes, average molecular weight
A polymer compound containing 45 to 95% by weight of a polyolefin compound of less than 3,000% in the resin component of the toner, and comprising a monomer component that is soluble in the carrier liquid and a monomer component that is sparingly soluble or insoluble in the carrier liquid. Since we used a liquid developer containing aqueous solution, etc.)
It improves the image reproducibility of electrophotographic printing plates, especially lithographic printing plates, which include the process of using the toner image area as a resist and etching the non-image area, and improves the fixability of the toner image and the mechanical In addition, the presence of the polyolefin improves printability such as ink receptivity of the printing ink. Examples Next, examples of the present invention will be described, but the present invention is not limited thereto. Note that parts indicate parts by weight. Example 1 FR844 (50% toluene solution of polydiethylaminoethyl methacrylate compound: manufactured by Mitsubishi Rayon Co., Ltd.) 2 parts Sanwax 171P 2 parts (polyethylene average molecular weight 1500: manufactured by Sanyo Chemical Co., Ltd.) Isopar G 11 parts The above mixture was heated to 90°C. Dissolved. The above mixture 15 parts MA-100 1 part (carbon black: manufactured by Mitsubishi Kasei Corporation) Isopar G 4 parts The above mixture was dispersed with glass beads for 10 hours,
This dispersion was diluted 60 times with Isopar G to obtain a liquid developer. Comparative Examples 1 and 2 In Example 1, instead of using Sunwax 171P, Sunwax 131P (average molecular weight 3500),
Liquid developers of Comparative Examples 1 and 2 were obtained in the same manner except that Sanwax 161P (average molecular weight: 5000) was used. Next, a composition containing 1 part by weight of ε-type copper phthalocyanine, 6 parts by weight of m-cresol phenol, 6 parts by weight of ethylene glycol monoethyl ether, and 24 parts by weight of ethylene glycol monoethyl ether was applied to an ultrasonic disperser at room temperature to homogenize the dispersion to obtain a photosensitive liquid. This photosensitive liquid was applied onto a roughened aluminum plate to a film thickness of 5 μm to obtain a printing original plate. This printing original plate is charged with a corona charging device, and an electrostatic latent image is obtained by performing image exposure through a lens system using a reflective positive on the original and 10 fluorescent lamps of 20W as a light source, and the electrostatic latent image is obtained using the liquid developer described above. I developed it. Perform fixing at room temperature and heat fixing,
A printing plate was obtained by immersing it in an alkaline aqueous solution consisting of sodium silicate and caustic soda and etching the photoconductive layer in the non-image area (the area to which no toner was attached). The image reproducibility of the photoconductive layer at this time was good. Next, use the above printing plate as an offset master,
It was subjected to printing and its printing durability was examined. The results are shown in the table.

[Table] In the above table, the residual degree (%) of the photoconductive layer refers to the adhesion of the photoconductive layer before etching with an alkaline etching solution as 100%, and etching with an alkaline etching solution using the toner image as a resist. The residual degree of the photoconductive layer after the treatment is expressed in %. If the toner image has poor resistance to the alkaline etching solution, the photoconductive layer will be eroded by the etching solution and exhibit a low residual value. From the above table, it is clear that the toner image created using the liquid developer of this example has high resistance to alkaline etching liquid even without heat fixing, and the printing plate has high printing durability. .
In addition, the image reproducibility of the printed matter is good, and the adhesion of the ink to the printing plate is also good. Example 2 Octadecyl methacrylate/methacrylic acid copolymer (90:5) 10% Isopar G solution 10 parts MA-100 (as described above) 1 part The above mixture was dispersed with glass beads for 5 hours.
Further, 1 part of Sunwax 151P (polyethylene, average molecular weight 2000, manufactured by Sanyo Chemical Co., Ltd.) was added to the above mixture, heated to 80°C, and further dispersed for 3 hours. This dispersion was diluted 80 times to obtain a liquid developer. When a printing plate was prepared using this liquid developer in the same manner as in Example 1, the printing durability of the toner image against an alkaline etching solution was good, and when this printing plate was subjected to offset printing, the printability was also good and it was 200,000 yen. It was possible to print more than one sheet. Example 3 2-ethylhexyl methacrylate/methyl methacrylate/N,N-dimethylaminoethyl methacrylate copolymer (7:2:1) 1 part Sunwax 171P (as described above) 1 part Fastgen Green S (phthalocyanine green:
(manufactured by Dainippon Ink) 1 part Isopar G 12 parts The above mixture was dispersed with glass beads for 10 hours. Note that during the first two hours of this dispersion, the mixture was heated to 80° C. or higher. This dispersion was diluted 70 times to obtain a liquid developer. When a printing plate was prepared using this liquid developer in the same manner as in Example 1, it had good printability and could print more than 200,000 sheets. Example 4 300g of Isopar H was placed in a container equipped with a stirrer, a thermometer, and a reflux condenser and heated to 90°C, and then a mixed solution of 200g of stearyl acrylate, 20g of glycidyl methacrylate, and 3g of azobisisobutyronitrile was added over 5 hours. dripped. Then acrylic acid
1 g of lauryl dimethylamine and 0.5 g of hydroquinone were added, and an esterification reaction was carried out at 90° C. for 10 hours. Next, add 300g of Isopar H and add 95
A mixture of 40 g of styrene monomer and 3 g of azobisisobutyronitrile was added over 3 hours at 0.degree. C., and the reaction was continued for a further 5 hours. Then this reactant
150g of Isopar H and 400g of Sanwax
60g of 171P (described above) was added and dissolved at 95°C, followed by reaction for 1 hour. Next, 10 g of hydroxyethyl methacrylate and 0.3 g of azobisisobutyronitrile were added to the reaction solution, and after polymerization at 95°C for 3 hours, the solid content was 18.0% and the particle size was 0.6 when rapidly cooled with stirring.
~1.0μ of latex was deposited. The above latex (solid content 18.0%)
150g Microlith Black CT (manufactured by Ciba) 30g Isopar H
A mixture consisting of 300 g was dispersed with glass beads for 10 hours to obtain a density toner, which was diluted 40 times with Isopar H to prepare a liquid developer. Next, a printing plate was prepared in the same manner as in Example 1, and the toner image had good resistance to alkaline etching liquid. When this printing plate was subjected to offset printing, it had good printability and could print more than 200,000 sheets. Ta. Example 5 Latex obtained in Example 4 (solid content 18.0%) 60g Carbon Black Mitsubishi #44 10g Isopar H 100
A mixed solution consisting of the following components was dispersed using glass beads for about 20 hours to obtain a concentrated toner, and this was diluted 40 times with Isopar H to prepare a liquid developer. Next, after forming an electrostatic latent image on a commercially available zinc oxide-resin dispersion electrophotographic master by a conventional method,
The above toner image was developed with the above developer and transferred by a bias roll method to a printing original plate prepared with a thickness of approximately 3μ on an aluminum plate grained with styrene-methacrylic acid (molar ratio 50:50) copolymer. did. Next, add 2.5% sodium carbonate to this printing plate.
When etching was performed using an aqueous solution, a printing plate was obtained in which the toner-free areas were removed.
The resistance to the aqueous sodium carbonate solution during etching was good, and when this printing plate was subjected to offset printing, more than 150,000 sheets could be printed. Example 6 Carbon black 1 part by weight Polyethylene (molecular weight 1500) 2 Octadecyl methacrylate/methacrylic acid copolymer (90:10) 1 GafacRB-410 (surfactant manufactured by Toho Chemical Co., Ltd.)
0.05〃 Isopar G 20 〃 The above mixture was dispersed with glass beads for 5 hours,
A liquid developer was prepared. Comparative Example 3 In the same manner as in Example 6, except that Kraton C-200, a hydrocarbon resin containing 1,3-pentadiene, was used instead of the octadecyl methacrylate/methacrylic acid copolymer (90:10). A liquid developer described in Publication No. 57-210347 was prepared. In the same manner as in Example 1, a printing original plate was prepared, an electrostatic latent image was formed thereon, and the image was developed using the liquid developer of Example 6 and Comparative Example 3, fixed, and etched. . Thereafter, image reproducibility and printing durability were evaluated in the same manner as in Example 1, and the results are shown in the table below.

[Table] From the table above, only when the liquid developer of Example 6, which is a combination of low molecular weight polyolefin and a specific polymer compound, is used, high alkaline etching solution resistance is exhibited, and even without heat fixing, high alkaline etching It can be seen that it exhibits etching solution resistance.

Claims (1)

[Scope of Claims] 1. After a toner image area is formed by electrophotography using a liquid developer on a printing original plate having a photoconductive layer on a conductive support, an area where this toner image area is not formed. In a printing plate production method in which a printing plate is created by removing a non-image area, the carrier liquid contains a toner whose main components are pigment and/or dye particles and a resin, and the resin is ( a) 5 to 55% by weight of a polymer compound consisting of a monomer component soluble in the carrier liquid and a monomer component poorly soluble or insoluble in the carrier liquid, and (b) a polyolefin compound with an average molecular weight of less than 3000.
A method for producing a printing plate, characterized in that a liquid developer containing 45 to 95% by weight is used. 2. The method for producing a printing plate according to claim 1, wherein the polyolefin compound (a) is a polyethylene compound. 3. The method for producing a printing plate according to claim 1, wherein the pigment and/or dye particles are carbon black. 4 The molecular weight of the polymer compound in (a) above is 30,000 or more
150,000. 150,000. 5. The method for producing a printing plate according to claim 1, wherein the toner image area is fixed at a room temperature of 40° C. or lower.