JP2006088613A - Original plate for planographic printing plate, bar application and manufacturing method for original plate, and printing method using original plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an original plate for a planographic printing plate, which prevents application defect, which has good performance and which can obtain a properly coated surface with stability and a uniform surface shape, and a bar application and manufacturing method for the original plate. <P>SOLUTION: In the original plate for the planographic printing plate, a hydrophilic layer coating liquid, and an image forming layer coating liquid containing thermally meltable particles are provided on a substrate in this order. In the bar application and manufacturing method for the original plate for the planographic printing plate, an image forming layer is formed by scraping off and applying an excessive quantity of image forming layer coating liquid by means of a bar, after the excessive quantity of image forming layer coating liquid is applied onto the substrate, coated with a continuously carried hydrophilic layer, through a filter; and the scraped-off image forming layer coating liquid is liquid-circulated and reused as a coating liquid. The bar application and manufacturing method for the original plate for the planographic printing plate, the original plate for the planographic printing plate, and a printing method using the original plate are characterized by satisfying the inequality: 5A≤B≤100A. In the inequality, A (μm) represents the largest mean particle diameter of the thermally meltable particle contained in the image forming layer coating liquid; and B (μm) represents the accuracy of filtering. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a lithographic printing plate precursor (also referred to as a lithographic printing plate material or a lithographic printing plate), a bar coating production method thereof, and a printing method using the same, and more specifically, image recording based on digital signals is possible. The present invention relates to a lithographic printing plate precursor capable of obtaining a stable printed matter without coating defects, and a bar coating production method thereof.

  In the conventional printing process, a negative or positive film is produced from a document image, the image is exposed to a lithographic printing plate precursor having a photosensitive layer on an aluminum grain support through the film, and development processing is performed with an alkaline developer. Thus, a lithographic printing plate is produced and attached to a printing machine for printing.

  In recent years, with the spread of computers, computer-to-plate (CTP) technology that draws original image data directly on a printing plate without using a film is becoming widespread, reducing the time and cost required for film production. Is becoming possible. Also, as a need for printed materials, there is a tendency for a small number of various types of products to print various kinds of high-quality images with the number of printed sheets of about several thousand to 10,000 sheets. For this reason, plate making using heat mode laser recording, which has a short drawing time and high resolution, is becoming the mainstream of CTP.

  Synchronizing with the spread of CTP, the printing environment has become an office, and an lithographic printing plate material that does not require an alkaline developer and does not require any development treatment from the viewpoint of environmental suitability has been desired. It was.

  A method for preparing a lithographic printing plate by attaching a lithographic printing plate precursor containing thermoplastic particles dispersed in a hydrophilic binder to a printing machine and developing on the printing machine is disclosed (for example, see Patent Documents 1 to 3). .) According to these techniques, it is possible to produce a printing plate without performing alkali development and without requiring a developing machine, and it is possible to provide a lithographic printing plate that does not require development processing in a pseudo manner.

  It is also described that a plastic film can be used as a support in recent years without using a hydrophilic aluminum substrate as a support for a lithographic printing plate precursor.

  Plastic film has lower thermal conductivity than metal, and can be efficiently used for image formation without diffusing heat generated in the heat-sensitive layer by laser exposure during image formation to the support. It has the advantage of being inexpensive compared to the body. As a printing plate using these plastic films as a support, examples of using a support having a corona-treated surface are mentioned (for example, see Patent Document 4), and a plasma-treated support is disclosed (for example, a patent). Reference 5).

  Various apparatuses are known as a coating apparatus used for manufacturing a lithographic printing plate precursor. For example, dip coating, roller coating, fountain coating, air knife, blade coating, bar coating, slide hopper, etc.

  In recent years, as a method of applying to the support that is continuously conveyed in the coating method using the above-mentioned coating device, as a method for thin film and high-speed coating, in recent years, a bar coating device has been widely used. There is known a bar coating method using the above.

  In the bar coating method, as a first step, an appropriate amount of coating solution is applied to the belt-like support by a roll coating device, and a bar coating device (the bar is stationary or rotating) is applied to the excess coating solution (primary film). Is a method of obtaining a desired film thickness (secondary film) by pressing a bar and scraping off an excessive coating solution. The final film thickness after scraping is determined only by the cut surface of the groove formed in the bar.

  In combination with the bar coating device, each of the above coating devices can be used as a device for applying an excessive coating liquid, but in general, a dip coating device, a roll coating device, a fountain coating device, a comma coating device, etc. Each device is used. Moreover, the coating device (for example, refer patent document 6) with which the excess coating and the bar coating device were integrated may be used.

  In the planographic printing plate, the content of providing an undercoat layer containing specific metal oxide particles on a support by a bar coating production method is described (for example, see Patent Document 7). There is no mention of a method for producing a stable lithographic printing plate without coating defects by the bar coating production method for the contained liquid.

There is a need for a method for producing a stable lithographic printing plate that does not require a special bar coating apparatus, and does not require any special change in the coating solution, and that does not have any coating defects due to the bar coating production method for liquids containing hot-melt particles. It was.
JP-A-9-123387 JP-A-9-123388 JP-A-9-131850 JP-A-9-314794 JP 11-245530 A Japanese Unexamined Patent Publication No. Hei 6-170312 JP 2002-154278 A

  The object of the present invention is to provide a lithographic printing plate precursor having a coating surface with no coating defects, a uniform surface shape and a good coating surface, and a good performance on a long belt-like support using a bar coating device, An object of the present invention is to provide a method for manufacturing the bar coating.

  The above object of the present invention can be achieved by the following configuration.

(Claim 1)
A method for bar coating production of a lithographic printing plate precursor comprising a hydrophilic layer coating solution on a plastic film support and an image forming layer coating solution containing at least heat-meltable particles in this order, wherein the image forming layer After applying an excessive amount of the image forming layer coating solution through a filter on a support coated with a hydrophilic layer that is continuously conveyed, an excess amount of the image forming layer coating solution is applied using a bar. The image forming layer coating solution formed by scraping and coating is circulated to form a coating solution again. The largest average particle diameter of the hot-melt particles contained in the image forming layer coating solution is A. (Μm), and the filter filtration accuracy is B (μm), 5A ≦ B ≦ 100A.

(Claim 2)
2. The method for bar coating production of a lithographic printing plate precursor according to claim 1, wherein 1 ≦ N ≦ 120, where N is the number of times that the image forming layer coating solution passes through the filter.

  However, the number N of times of passage through the filter means the number obtained by dividing the total amount of liquid sent by the amount of stock solution.

(Claim 3)
A lithographic printing plate precursor produced by the bar coating production method according to claim 1 or 2.

(Claim 4)
A lithographic printing plate precursor according to claim 3, wherein the lithographic printing plate precursor is subjected to laser exposure on the basis of image information and subjected to on-press development processing for printing.

  According to the present invention, a lithographic printing plate precursor having a stable and favorable coating surface having a uniform surface shape and good coating performance on a long belt-like support using a bar coating apparatus and its performance, and its bar A coating manufacturing method could be provided.

  The present invention will be described in more detail. The present invention has been found for the first time by satisfying the above requirements that a long and stable coated surface can be obtained without coating defects and the printing performance can be improved.

That is, after an excessive amount of the image forming layer coating solution is applied through a filter on the support on which the hydrophilic layer to be continuously conveyed is coated, the excess amount of the image layer coating solution is scraped off using a bar. In the bar coating method that performs coating and circulating the image forming layer coating liquid,
A (μm) is the largest average particle diameter of the heat-fusible particles,
If the filter filtration accuracy is B (μm),
It is important that 5A ≦ B ≦ 100A. Furthermore, it is preferable that N is 1 ≦ N ≦ 120 as the number of times the image forming layer coating solution passes through the filter.

  Regarding the filter filtration accuracy B, if the filter filtration accuracy B is smaller than 5A of the largest average particle diameter A of the heat-meltable particles, excessive shearing is applied to the particles when the heat-meltable particles pass through the gap of the filter. It turns out that it deforms, agglomerates, melts, so that it does not become a uniform coating solution, clogs the bar, and a uniform and stable coating property cannot be obtained, and the actual performance deteriorates. It was.

  If the filter filtration accuracy B is larger than 100A of the largest average particle diameter A of the heat-melting particles, the heat-melting particles themselves will not be excessively sheared when passing through the gap of the filter, but foreign matter in the coating solution It was found that foreign substances in the coating environment could not be removed, uniform and stable coating properties could not be obtained, and actual performance deteriorated.

  Regarding the number N of times the image forming layer coating solution passes through the filter, it is preferable that 1 ≦ N ≦ 120. If there is no filter passage, foreign matter in the coating solution and foreign matter in the coating environment cannot be removed, uniform and stable coatability cannot be obtained, and actual performance is also deteriorated. When N exceeds 120, the heat-meltable particles pass through the gap of the filter an excessive number of times, so that the shear is applied to the particles, and the particles themselves are deformed, agglomerated, or melted. It has been found for the first time by the present invention that it does not become a coating solution and the actual performance deteriorates.

  The plastic film support used in the present invention is not particularly limited, and includes polyethylene terephthalate, polyethylene naphthalate, polyimide, polyamide, polypropylene, polyethylene, polyvinyl chloride, acetate, nylon, polyetherimide, polycarbonate, polysulfone, and polyphenylene oxide. , Polyphenylene sulfide, cellulose esters and the like. These plastic films are preferably subjected to easy adhesion treatment or undercoat layer coating on the coated surface in order to improve adhesion with the coated layer. Examples of the easy adhesion treatment include corona discharge treatment, flame treatment, and ultraviolet irradiation treatment. Examples of the undercoat layer include a layer containing gelatin or latex.

  In the present invention, the length, shape, roughness type, etc. of the filter are not particularly limited. Filter shapes include pleats, depths, pleated depths, and the like, and those having different shapes may be combined.

  The number of filters may be single, a plurality of different types or the same type may be used, and the filters may be combined in series or in parallel.

  The bar in the present invention is used without particular limitation such as a bar around which a wire is wound or a bar around which no wire is wound, and the material is also used without limitation such as iron or stainless steel. Further, the surface may be plated as necessary. The surface plating treatment may be used without particular limitation as long as it satisfies the scope of the present invention, and examples thereof include nickel, cobalt, hard chromium, titanium, and DLC (diamond-like carbon). The plating process may be performed alone, or a plurality of processes such as a hard chrome plating process may be further performed on the nickel plated process.

  A binder resin is used for the hydrophilic layer and the image forming layer of the lithographic printing original plate, and the binder resin can be used without any particular limitation. For example, vinyl chloride resins such as polyurethane, polyester, vinyl chloride copolymer, vinyl chloride resins such as vinyl chloride-vinyl acetate copolymer, polyolefin resins such as butadiene-acrylonitrile copolymer, polyvinyl butyral, etc. Polyvinyl acetal resin, cellulose resin such as nitrocellulose, styrene resin such as styrene-butadiene copolymer, acrylic resin such as polymethyl methacrylate, polyamide, phenol resin, epoxy resin, phenoxy resin, polyvinyl butyral, polyvinyl aceto There are acetal resins such as acetal and polyvinyl formal, and water-soluble resins such as polyvinyl alcohol and gelatin.

  The image forming layer of the lithographic printing plate precursor according to the invention contains heat-meltable particles that can be fused by heat, but can also contain a substance that exhibits lipophilicity by heat.

Examples of heat-meltable particles that can be fused by heat include waxes, acrylic resins, ionomer resins, vinyl acetate resins, vinyl chloride resins, synthetic rubbers, polyurethane resins, polyester resins, fluorine resins, silicone resins, etc. And those obtained from latex or emulsion dispersed in water. Of these, those having a melting point of 70 to 180 ° C. are preferable, and the hydrophilic component of the surface energy is preferably 10 μN / cm ² or less. When the melting point is lower than this temperature, the performance during storage tends to deteriorate, and when it is higher than this temperature, the image strength cannot be obtained and the printing durability tends to deteriorate. Further, when the surface energy is within this range, the ink deposition property of the image portion is improved. In this respect, waxes, acrylic resins, and synthetic rubbers are particularly preferable as the hot-melt material.

  Examples of waxes that can be used in the present invention include carnauba wax, beeswax, whale wax, wood wax, jojoba oil, lanolin, ozokerite, paraffin wax, montan wax, candelilla wax, ceresin wax, microcrystalline wax, rice wax, and the like. Natural wax, polyethylene wax, Fischer-Tropsch wax, montan wax derivative, paraffin wax derivative, microcrystalline wax derivative, higher fatty acid and the like. In order to facilitate emulsification, these waxes can be oxidized to introduce polar groups such as hydroxyl groups, ester groups, carboxyl groups, aldehyde groups, and peroxide groups.

  A hydrophilic binder is added to the image forming layer containing heat-fusible particles that can be fused by heat in order to give the film-forming property of the image-forming layer within a range that does not impair the fusing property of the particles during laser exposure. You may make it contain.

  Usable hydrophilic binders include, for example, polyvinyl alcohol, poly (meth) acrylic acid, poly (meth) acrylamide, polyhydroxyethyl (meth) acrylate, polyvinyl methyl ether, or natural binders such as gelatin, polysaccharides, Examples thereof include dextran, pullulan, cellulose, gum arabic, and arginic acid. Further, the hydrophilic binder may be a water-insoluble, alkali-soluble or swellable resin having a phenolic hydroxy group and / or a carboxyl group. Various surfactants and colloidal silica can also be used.

  As a substance that exhibits lipophilicity by heat, a hot-melting substance having a melting point of 70 to 180 ° C. can be used. As waxes, carnauba wax, beeswax, whale wax, wood wax, jojoba oil, lanolin, ozokerite, paraffin wax, Natural waxes such as montan wax, candelilla wax, ceresin wax, microcrystalline wax, rice wax, polyethylene wax, Fischer-Tropsch wax, montan wax derivative, paraffin wax derivative, microcrystalline wax derivative, higher fatty acid, etc. are acrylic resins In, for example, methyl methacrylate, butyl acrylate, octyl acrylate, 2-ethylhexyl acrylate, styrene, or the like is copolymerized, or synthetic rubbers are polybutadiene. , Polyisoprene, polychloroprene, styrene-butadiene copolymer, acrylic ester-butadiene copolymer, methacrylic ester-butadiene copolymer, isobutylene-isoprene copolymer, acrylonitrile-butadiene copolymer, acrylonitrile- Examples include isoprene copolymers and styrene-isoprene copolymers. In addition, ionomer resins, vinyl acetate resins, vinyl chloride resins, polyurethane resins, polyester resins, fluorine resins, silicone resins, and the like can be used. These lipophilic agents are preferably used in the form of an aqueous dispersion in terms of ease of coating. As another embodiment, there can be mentioned a thermal cross-linking agent covered with a thermally destructible hydrophilic coating material, and a thermal cross-linking agent in which a functional group is blocked by a protecting group dissociated by heat. These thermal crosslinking agents are described as lipophilic components microencapsulated in JP-A Nos. 7-1849, 7-1850, 9-311443, 10-6468, and 10-111168.

  The hydrophilic layer of the present invention is defined as a layer that can take in more water when an emulsified solution of water and ink comes during printing.

  In the present invention, other layers may be formed between the substrate and the hydrophilic layer. For example, there are an undercoat layer that improves the adhesion of the hydrophilic layer, a swell forming layer that imparts a gentle roughness at a long wavelength, and a cushion layer that relieves stress applied to the hydrophilic layer. Any one of these layers may contain a photothermal conversion material.

  The organic solvent used in the coating solution of the present invention is not particularly limited as long as it can dissolve or disperse the above composition. For example, alcohols (ethanol, propanol, etc.), cellosolves (methyl cellosolve, ethyl cellosolve), Aromatics (toluene, xylene, chlorobenzene, etc.), ketones (acetone, methyl ethyl ketone, etc.), ester solvents (ethyl acetate, butyl acetate, etc.), ethers (tetrahydrofuran, dioxane, etc.), halogenated solvents (chloroform, dioxane, etc.) Chlorobenzene, etc.), amide solvents (eg, dimethylformamide, N-methylpyrrolidone, etc.) and the like can be used.

  As an exposure light source for forming an image on the lithographic printing plate precursor according to the invention, any light source capable of being sensitive to the metal ion complex dye represented by the above general formula can be used without particular limitation. Among them, in order to obtain a high resolution, an electromagnetic wave whose energy application area can be narrowed down, particularly an ultraviolet ray having a wavelength of 1 nm to 1 mm, a visible ray, and an infrared ray are preferable. As a light source capable of applying such light energy, for example, a laser, Light emitting diodes, xenon flash lamps, halogen lamps, carbon arc lamps, metal halide lamps, tungsten lamps, quartz mercury lamps, high pressure mercury lamps and the like can be mentioned. The energy applied at this time can be selected and used in a timely manner by adjusting the exposure distance, time, and intensity depending on the type of image forming material.

Laser light sources used in the printing method of the present invention are generally well-known solid lasers such as ruby laser, YAG laser, and glass laser; He-Ne laser, Ar ion laser, Kr ion laser, CO ₂ laser, CO laser Gas lasers such as He-Cd laser, N ₂ laser, excimer laser; semiconductor lasers such as InGaP laser, AlGaAs laser, GaAsP laser, InGaAs laser, InAsP laser, CdSnP ₂ laser, GaSb laser; chemical laser, dye laser, etc. Among these, in order to efficiently cause ablation, a laser having a wavelength of 600 to 1200 nm is preferable in terms of sensitivity because it can convert light energy into heat energy.

  The printing method of the present invention is characterized in that printing is performed without performing development processing after laser exposure based on image information.

  The on-press development in the present invention has the following contents. A method for removing an unexposed portion of an image forming layer of a lithographic printing plate precursor by mounting the exposed lithographic printing plate precursor on a cylinder of a printing press and supplying dampening water and ink while rotating the cylinder. It is. In other words, the lithographic printing plate precursor is exposed and then mounted on a printing machine as it is, and the development process is completed in a normal printing process.

  Hereinafter, embodiments of the present invention will be described, but the present invention is not limited thereto.

Example 1
The following undercoat layer was provided on a 175 μm 1185 mm wide PET film of Teijin-Dupont Films Melinex 765.

<< Preparation of undercoat layer >>
The both sides of the film were subjected to a corona discharge treatment of 8 W / m ² · min, and then the following undercoat coating solution a-1 was applied on one side to a dry film thickness of 0.8 μm and dried. It was set as subbing layer A-1. In addition, the following surface coating solution b-1 for antistatic processing is applied to the opposite surface so as to have a dry film thickness of 0.8 μm, and dried to provide an antistatic processing undercoat having a surface electrical resistance of 10 ⁶ Ω. Layer B-1.

  Subsequently, the surface of each undercoat layer was subjected to plasma treatment under the following plasma treatment conditions.

<< Undercoat coating liquid a-1 >>
Butyl acrylate (30% by mass)
t-Butyl acrylate (20% by mass)
Styrene (25% by mass)
2-Hydroxyethyl acrylate (25% by mass)
270 g of copolymer latex liquid (solid content 30%)
Hexamethylene-1,6-bis (ethylene urea) 0.8g
Polystyrene fine particles (average particle size 3 μm) 0.05 g
Colloidal silica (average particle size 90μm) 0.1g
Finish to 1 liter with water.

<< Undercoat coating liquid b-1 >>
Tin oxide (average particle size 36nm doped with 0.1% indium)
Amount to be 0.26 g / m ² Copolymer latex liquid of butyl acrylate (30% by mass), styrene (20% by mass), glycidyl acrylate (40% by mass) (solid content 30%) 270 g
Hexamethylene-1,6-bis (ethylene urea) 0.8g
Finish to 1 liter with water.

<< Plasma treatment conditions >>
Using a batch type atmospheric pressure plasma processing apparatus (AP-I-H-340, manufactured by EC Chemical Co., Ltd.), the high frequency output is 4.5 kW, the frequency is 5 kHz, the processing time is 5 seconds, and the gas conditions are argon, nitrogen and Plasma treatment was performed at hydrogen volume ratios of 90%, 5%, and 5%, respectively.

<< Production of hydrophilic layer >>
A hydrophilic layer was prepared by applying the following coating solution on the obtained PET support with the underdrawn.

  In addition, the following "part" represents a "mass part".

<First hydrophilic layer coating solution>
Snowtex-XS [Nissan Chemical Industry Co., Ltd.] Average particle size 0.005 μm 9.62 parts Snowtex-ZL [Nissan Chemical Industry Co., Ltd.] Average particle size 0.085 μm 0.6 parts Silton JC-40 [Mizusawa Chemical Industries Ltd.] Average particle size 4.0 μm 2.22 parts STM-6500S [Nissan Chemical Industry Co., Ltd.] Coated particle average particle size 6.5 μm 3 parts Sodium carboxymethylcellulose [Kanto Chemical Co., Ltd.] 0.12 parts Mineral colloid MO [ Wilber-Ellis Co., Ltd.] 0.22 parts MF-4500 Black [Daiichi Seika Kogyo Co., Ltd.] Photothermal conversion material 4 parts Trisodium phosphate 12 water [Kanto Chemical Co., Ltd.] 0.06 parts FZ-2161 [Nihon Unicar Co., Ltd.] 0.16 parts pure water 80 parts The first hydrophilic layer using a bar so that the first hydrophilic layer has a dry film thickness of 1.8 (μm) Coating solution was applied.

  Furthermore, the following 2nd hydrophilic layer coating liquid was apply | coated so that it might become a dry film thickness of 0.6 micrometer on the 1st hydrophilic layer, and the 2nd hydrophilic layer was provided.

<Second hydrophilic layer coating solution>
Snowtex-S [Nissan Chemical Industry Co., Ltd.] Average particle size 0.009 μm 1.56 parts Snowtex-PSM [Nissan Chemical Industry Co., Ltd.] Average particle size 0.095 μm 2.34 parts Shilton JC-20 [Mizusawa Chemical Industry] Corporation] Average particle size 1.5 μm 1.2 parts AMT-08 [Mizusawa Chemical Co., Ltd.] Average particle size 0.95 μm 3.6 parts MP-4540 [Nissan Chemical Industry Co., Ltd.] Average particle size 0.45 μm 1 .8 parts sodium carboxymethylcellulose [Kanto Chemical Co., Ltd.] 0.12 parts mineral colloid MO [Wilver-Ellis Co., Ltd.] 0.24 parts MF-4500 black [Daiichi Seika Kogyo Co., Ltd.] Photothermal conversion material 1.08 parts phosphorus Trisodium acid 12 water [Kanto Chemical Co., Ltd.] 0.06 parts pure water 88 parts << Preparation of image forming layer >>
The following image forming layer coating solution was applied to the obtained second hydrophilic layer laminate using a bar coating device so as to have a dry film thickness of 0.55 (g / m ² ) to obtain a lithographic printing plate precursor.

  At this time, the filter used was SL-300 (filter filtration accuracy B is 30 μm) from Loki Techno Co., Ltd.

<Image forming layer coating solution>
HI-DISPER A-206 [Gifu Shellac Manufacturing Co., Ltd.] Heat-meltable particles (average particle size 0.5 μm) 2.5 parts DL-522 [Nippon Catalyst Co., Ltd. average molecular weight 170.000] 0.75 parts HI- DISPER A118 [Gifu Shellac Manufacturing Co., Ltd.] Hot-melt particles (average particle size 0.3 μm) 6.55 parts pure water 88.5 parts isopropyl alcohol 1.5 parts Penon JE-66 [Nissho Chemical Co., Ltd.] 0 .2 parts 101. Therefore, no. A of 101 is 0.5 μm.

  The following evaluation was performed when the image forming layer was applied.

~ Evaluation ~
Evaluation of coating defects The repellency and uneven coating defects Total per coating sample m ² were counted. The larger the number of coating defects, the worse.

Evaluation of coating defect size (missing size) The size (μm) of the largest coating failure per coating sample m ² was measured.

Vertical stripe (application direction stripe)
The rank per coated sample m ² was evaluated as follows.
5; No occurrence 4; Little occurrence, no actual damage 3; Little occurrence, actual damage concern level 2; Occurrence, actual damage 1; Multiple occurrence, actual damage

Bar reusability The coated bar was washed by the following method, and the degree of clogging and reusability of the bar was visually evaluated.

  2 L of water was placed in an ultrasonic cleaner FU-926 of Tokyo Glass Instrument Co., Ltd., and 10 ml of ultrasonic cleaner Contaminone US manufactured by Wako Pure Chemical Industries, Ltd. was added for cleaning for 24 hours.

Evaluation rank 3: No clogging, no problem with reuse 2; Little clogging, no problem with reuse 1; Many clogs, no reuse.

  The following evaluation was further performed after the application of the image forming layer.

Exposure and printing of lithographic printing plate precursor The obtained lithographic printing plate precursor was subjected to 50% by using a semiconductor laser light source (light source wavelength of 830 nm, spot size of 10 μm and resolution of 2000 dpi in both scanning direction and sub-scanning direction) corresponding to 175 lines. The halftone dot image and the solid image were exposed with the irradiation energy amount on the image surface being 250 mJ / cm ² while changing the scanning speed. In addition, dpi represents the number of dots per 2.54 cm.

  The exposed lithographic printing plate precursor is attached to a Heidel GTO printing machine without developing, and 45 times water diluted solution of SEU-3 (manufactured by Konica Co., Ltd.) as an etchant and HiEcho (Toyo Ink Co., Ltd.) as an ink )), And printing was performed using high-quality paper as printing paper. Printing was performed in an environment of 23 ° C. and RH 48%.

Finished quality of printed matter The finished quality of the 30th sheet after the start of printing was visually evaluated by the following rank.
5: Good quality 4; Quality is slightly inferior, but no problem in use 3; Quality is slightly inferior, but usable level 2; Poor quality, actual concern level 1; Poor quality, unusable Printing The number of parts that were not evaluated was visually evaluated. The larger the number, the higher the printing durability and the better.

  Samples with different numbers of filter passes, filters with different filtration accuracy, and comparative samples were also prepared and evaluated in the same manner. The above results are shown in Table 1.

The filters used are as follows.
SL-010 from Loki Techno Co., Ltd. (filtering accuracy 1 μm)
SL-070 from Loki Techno Co., Ltd. (filter filtration accuracy 7μm)
Loki Techno Co., Ltd. SL-500 (Filter filtration accuracy 50μm)
Loki Techno SL-700 (filtering accuracy 70μm)
The numbers described in column B of Table 1 indicate that the filter with the above filtration accuracy was used.

  The number N of times that the image forming layer coating solution passes through the filter is shown in the N times column of Table 1.

  As can be seen from the table, if the present invention is satisfied; coating properties and printing performance are stable and good.

Claims (4)

A method for bar coating production of a lithographic printing plate precursor comprising a hydrophilic layer coating solution on a plastic film support and an image forming layer coating solution containing at least heat-meltable particles in this order, wherein the image forming layer After applying an excessive amount of the image forming layer coating solution through a filter on a support coated with a hydrophilic layer that is continuously conveyed, an excess amount of the image forming layer coating solution is applied using a bar. The image forming layer coating solution formed by scraping and coating is circulated to form a coating solution again. The largest average particle diameter of the hot-melt particles contained in the image forming layer coating solution is A. (Μm), and the filter filtration accuracy is B (μm), 5A ≦ B ≦ 100A. 2. The method for bar coating production of a lithographic printing plate precursor according to claim 1, wherein 1 ≦ N ≦ 120, where N is the number of times that the image forming layer coating solution passes through the filter.
However, the number N of times of passage through the filter means the number obtained by dividing the total amount of liquid sent by the amount of stock solution. A lithographic printing plate precursor produced by the bar coating production method according to claim 1 or 2. A lithographic printing plate precursor according to claim 3, wherein the lithographic printing plate precursor is subjected to laser exposure on the basis of image information and subjected to on-press development processing for printing.