JP2008200644A - Coating method, lithographic printing original plate and printing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a coating method of a lithographic printing plate which forms a coating surface with a uniform, stable and good surface shape without a coating fault on a supporting body of a long belt shape using a pick-up roll coater, and to provide a printing method. <P>SOLUTION: The coating method picks up a coating liquid by a pick-up roll to transfer and coat it, wherein the static surface tension of the coating liquid is 40×10<SP>-5</SP>N/cm or above and the pick-up roll is a grooved roll. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a lithographic printing plate precursor, and more specifically, a lithographic printing plate precursor coating method capable of recording an image based on a digital signal and capable of obtaining a stable printed matter without coating defects. The present invention relates to an obtained lithographic printing plate precursor and a printing method.

  In the conventional printing process, a negative or positive film is produced from an original image, and the image is exposed to a lithographic printing plate material (also referred to as a lithographic printing plate precursor) having a photosensitive layer on an aluminum grain support through the film. A lithographic printing plate is produced by developing with an alkaline developer, and this is mounted on a printing press 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 required for film production, Cost reduction 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 from the standpoint of environmental suitability, a lithographic printing plate material that does not require an alkaline developer and does not require any development processing has been desired. It was.

  For example, in JP-A-9-123387, 9-123388, and 9-131850, a lithographic printing plate precursor containing thermoplastic particles dispersed in a hydrophilic binder is attached to a printing machine, A method for producing a lithographic printing plate is disclosed. 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.

  In lithographic printing plate precursors, it has recently been described that a plastic film can be used as a support without using a hydrophilic aluminum substrate as the support.

  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.

  JP-A-9-314794 discloses examples of using a support having a corona-treated surface as a printing plate using these plastic films as a support, and JP-A-11-245530 discloses a plasma treatment. A support is disclosed.

  Various apparatuses are known as coating apparatuses. For example, dip coating, bar coating, fountain coating, air knife, blade coating, bar coating, slide hopper, etc.

  As a method for simply applying to a continuously transported support in the application method using the above-described application apparatus, as one of the methods that has recently been frequently used for thin film and high-speed application, There is known a pick-up coating method using a coating device that picks up the film.

Although there is a description of roll coater coating using a grooved roll as a pickup roll in the pickup coating method (see, for example, Patent Document 1), the static surface tension of the coating liquid is not described, and the coating stability of these liquids is improved. It is not described, and it has been desired to stably apply even a liquid having a high static surface tension.
JP 2006-88045 A

  The present invention provides a method for producing a lithographic printing plate by which a long and strip-shaped support using a pickup roll coating apparatus is free from coating defects, has a uniform surface shape, has a uniform and stable coating surface, and has good performance. It is to provide a method.

  The above problem could be solved by the following configuration.

1. In a coating method in which a coating liquid is picked up by a pick-up roll, transferred to a substrate, and coated, the static surface tension of the coating liquid is 40 × 10 ^{−5 to} 100 × 10 ⁻⁵ N / cm or more and the pick-up roll is a grooved roll A coating method characterized by the above.

  2. 2. The coating method according to 1 above, wherein the pitch interval between the grooves of the pickup roll is 0.1 to 5 mm and the groove width is 0.1 to 1.0 mm.

  3. 3. The coating method according to 1 or 2 above, wherein a grooved angle of the pickup roll is 30 to 60 degrees.

  4). 4. The coating method according to any one of 1 to 3, wherein a peripheral speed of the pickup roll is 1 m / min to 20 m / min.

  5. A lithographic printing plate precursor formed by the coating method described in any one of 1 to 4 above.

  6). 6. A printing method comprising printing the lithographic printing plate precursor as described in 5 above after laser exposure based on image information and after on-press development.

  The method of the present invention makes it possible to produce a lithographic printing plate precursor having good performance without causing coating defects even when a coating solution having a large static surface tension is used.

  Hereinafter, the present invention will be described in detail.

  A pick-up roll type coating apparatus used for producing the planographic printing plate precursor of the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic configuration diagram of a pickup roll type coating apparatus.

  The support body 10 unwound from a roll (not shown) wound in a roll is conveyed between the backup roll 2 and the pickup roll 1, and the coating liquid 5 picked up by the pickup roll 1 is the support body 10. It is applied on top, regulated to a specified thickness between the scraping roll 3 and the backup roll 4, applied with a constant thickness, and conveyed to the drying process.

  The pickup roll of the present invention is characterized by using a grooved roll.

  FIG. 2 is a diagram showing the groove angle, pitch interval, and groove width of the grooved roll. FIG. 2 (a) is a front view of the grooved roll 1, in which a groove 6 is formed on the surface of the pickup roll, and an angle θ formed between the rotation axis of the roll and the groove 6 is defined as a groove angle. Call. 2B to 2E are diagrams showing examples of the cross-sectional shape of the kerf 6, where P represents the pitch and L represents the inter-groove width.

  The present invention has been found to be achieved for the first time by satisfying the above claims.

That is, in the method of picking up a coating liquid with a pick-up roll, transferring it to a support and applying it, it is necessary that the static surface tension of the coating liquid is 40 × 10 ⁻⁵ N / cm or more and the pick-up roll is a grooved roll. And

It has been found by the present invention that the groove of the pickup roll is very important for a liquid having a static surface tension of 40 × 10 ⁻⁵ N / cm or more.

When the static surface tension of the coating solution is 40 × 10 ⁻⁵ N / cm or more, the groove is not grooved on the pickup roll surface. It was found that a liquid flow was generated on the roll surface without being transferred, so that the liquid was not evenly transferred to the support, thereby causing coating failures such as streaks and repellency.

The upper limit of the static surface tension of the coating solution is not particularly limited, but is preferably 120 × 10 ⁻⁵ N / cm or less from the viewpoint of transferability to a support.

  Furthermore, in order to prevent the liquid in the liquid storage container picked up by the pick-up roll peripheral speed from being bubbled and to prevent excessive liquid transfer to the support, it is important to make the speed low, but conversely the liquid having a high static surface tension. Then, it was found that the liquid pick-up property becomes non-uniform when the pick-up roll peripheral speed is slowed down.

  In this case as well, it was found that good applicability can be obtained by grooving the pickup roll.

  The pick-up roll peripheral speed is preferably 1 m / min to 20 m / min in order to prevent bubbling of liquid in the liquid reservoir to be picked up and excessive liquid transfer to the support. If it exceeds 20 m / min, the liquid tends to foam easily, and if it is slower than 1 m / min, the pick-up property tends to be non-uniform.

  The pitch interval, the groove width, and the groove angle are not particularly limited, but the pitch interval is 0.1 to 5 mm and the groove width is 0. More preferably, the angle is 1 to 1.0 mm and the groove angle is 30 to 60 degrees.

<Support>
The support used in the present invention is not particularly limited, and paper treated with metal, plastic film, polyolefin, etc., and a composite base material obtained by appropriately bonding these materials can also be used.

  Examples of the plastic film include polyethylene terephthalate, polyethylene naphthalate, polyimide, polyamide, polypropylene, polyethylene, polyvinyl chloride, acetate, nylon, polyetherimide, polycarbonate, polysulfone, polyphenylene oxide, polyphenylene sulfide, and cellulose esters. it can. 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.

  As the support, metal is aluminum.

  In this case, a pure aluminum plate, an aluminum alloy plate, or the like may be used.

  Various aluminum alloys can be used as the support, such as alloys of aluminum and metals such as silicon, copper, manganese, magnesium, chromium, zinc, lead, bismuth, nickel, titanium, sodium, iron, etc. Aluminum plates manufactured by various rolling methods can be used. In addition, a recycled aluminum plate obtained by rolling recycled aluminum ingots such as scrap materials and recycled materials that are becoming popular in recent years can also be used.

<binder>
The binder used in the present invention can be used without any particular limitation.

  Binder resins include polyurethane, polyester, vinyl chloride resins such as vinyl chloride copolymers, vinyl chloride resins such as vinyl chloride-vinyl acetate copolymers, polyolefin resins such as butadiene-acrylonitrile copolymers, polyvinyl Polyvinyl acetal resin such as butyral, 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 And acetal resins such as polyvinyl acetoacetal and polyvinyl formal, and water-soluble resins such as polyvinyl alcohol and gelatin.

  The binder resin may be used alone or in combination of two or more.

<Particulate matter>
The coating liquid for forming the lithographic printing plate precursor according to the present invention may contain particles according to performance.

  Examples of the particulate material include an inorganic or organic filler.

For example, carbon black, graphite, TiO ₂ , BaSO ₄ , ZnS, MgCO ₃ , CaCO ₃ , ZnO, CaO, WS ₂ , MoS ₂ , MgO, SnO ₂ , Al ₂ O ₃ , α-Fe ₂ O ₃ , α- _{FeOOH, SiC, CeO 2, BN} , SiN, MoC, BC, WC, titanium carbide, corundum, artificial diamond, garnet, garnet, silica rock, tripoli, diatomaceous earth, an inorganic filler and polyethylene resin particles, such as dolomite, fluororesin Examples thereof include organic fillers such as particles, guanamine resin particles, acrylic resin particles, silicon resin particles, and melamine resin particles.

  Examples of the particulate material include a filler having a core-shell structure.

  The particle having a core-shell structure is a particle obtained by fixing particles having a particle size smaller than that of the core to a portion that becomes a shell on the surface of the core particle.

  The core particles and the particles that become the shell may be inorganic particles or organic particles.

  The core particles may be fixed (coated) in a number of layers with the shell particles.

  The average particle diameter of the core particles is preferably from 0.1 to 15 μm, more preferably from 1 to 10 μm.

  The average particle size of the particles that become the shell is preferably 1/3 or less, more preferably 1/10 or less, of the average particle size of the core particles. It is preferable that the average particle size of the particles in the shell portion does not exceed 15 μm, and is preferably 0.1 μm or more.

  The coverage of the small particles fixed on the surface of the core particles can be arbitrarily selected within the range in which the effect of the present invention appears.

  For example, the particles of the shell may be formed by a method using the heteroaggregation method described in “New Development of Fine Particle Polymer” edited by Toray Research Center Co., Ltd., a method using a polymerization reaction from the surface of the core particle, edited by the Powder Engineering Society It can be easily produced using a dry coagulation stirring method using a hybridizer described in “Particle Design Engineering”. Certain core-shell particles can be produced by precipitating small particles on the surface of the core particles.

  An example of the particulate material is wax.

  Specific examples of the wax include solid waxes such as beeswax, candelilla wax, paraffin wax, ester wax, montan wax, carnauba wax, amide wax, polyethylene wax, and microcrystalline wax.

  Specific compounds as silicon compounds (including wax-like compounds) include straight silicone oils such as dimethyl silicone oil, methylphenyl silicone oil, and methylhydrogen silicone oil, olefin-modified silicone oil, polyether-modified silicone oil, and epoxy. Modified silicone oil, epoxy / polyether modified silicone oil, alcohol modified silicone oil, fluorine modified silicone oil, amino modified silicone oil, phenol modified silicone oil, mercapto modified silicone oil, carboxy modified silicone oil, higher fatty acid modified silicone oil, carnauba modified Silicone oil, amide-modified silicone oil, radical-reactive silicone oil such as (meth) acrylic-modified silicone oil, silicone diol, silicon Terminal reactive silicone oil diamine, a halogen group, an alkoxy group, and an ester group, an amide group, an organic modified silicone oil modified with an imide group.

Examples of particles include metal atom-containing particles. Metal atom-containing particles are metals such as iron, chromium, manganese, cobalt, nickel, copper, zinc, titanium, silver, aluminum, gold, platinum, or oxides thereof. The compound is a general term.

  Examples of the metal atom-containing particles include ferromagnetic iron oxide powder, ferromagnetic metal powder, and cubic plate powder.

Examples of the ferromagnetic iron oxide include γ-Fe ₂ O ₃ , Fe ₃ O ₄ , or intermediate iron oxides represented by FeOx (1.33 <x <1.50).

Ferromagnetic metal powders include Fe, Co, Fe—Al, Fe—Al—Ni, Fe—Al—Zn, Fe—Al—Co, Fe—Al—Ca, Fe—Ni. Fe-Ni-Al, Fe-Ni-Co, Fe-Ni-Zn, Fe-Ni-Mn, Fe-Ni-Si, Fe-Ni-Si-Al-Mn, Fe-Ni -Si-Al-Zn, Fe-Ni-Si-Al-Co, Fe-Al-Si, Fe-Al-Zn, Fe-Co-Ni-P, Fe-Co-Al-Ca Ferromagnetic metal powders such as metal magnetic powders mainly composed of Ni, Co, Fe, Ni, Co, etc. Among them, Fe metal powders are preferred, for example, Co-containing γ-Fe ₂ O ₃ , Co coated Adhered γ-Fe ₂ O ₃ , Co-containing Fe ₃ O ₄ , Co-coated Fe ₃ O ₄ , Co-containing magnetic Fe Examples include cobalt-containing iron oxide magnetic powders such as Ox (4/3 <x <3/2) powders.

<Grooved pickup roll>
Pickup Roll The pickup roll referred to in the present invention is defined as a roll that picks up a coating liquid and transfers it to a substrate.

  The liquid transferred by the pick-up roll may be the final coating amount or more, and when it is not the final coating amount, a method of scraping the liquid transferred by the pick-up roll with a wire bar may be mentioned.

  In this case, as a first step, an appropriate amount of coating solution is applied to the belt-like support by a pick-up roll coating device, and the excess coating solution (primary film) is coated with a bar coating device (the bar is stationary or rotating). In this method, a desired film thickness (secondary film) is obtained by pressing a bar and scraping off an excessive coating solution.

-Groove cutting Groove cutting in the present invention means having a plurality of kerfs on the roll surface. Even if it forms by winding a wire around a roll, a groove may be produced by engraving, and it is used without particular limitation.

  Examples of the shape of the cut groove include groove shapes such as a square shape, a trapezoidal shape, a V shape, and a U shape. The kerf may be parallel to the roll rotation direction or may be spiral.

・ Grooving angle Draw a parallel line to the axis of the pick-up roll and define it as the angle from there.

・ Material The material of the pick-up roll can be used without any restriction.

  Examples of rubber include urethane rubber, butyl rubber, and ethylene / propylene rubber.

Examples of the metal include iron, copper, and AL, and AL is preferable from the viewpoint of workability and corrosion.
Surface plating treatment 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.

<Printing method and image exposure>
The exposure light source for forming an image on the lithographic printing plate precursor according to the invention 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.

<On-machine development>
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.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in detail, the aspect of this invention is not limited to this. In addition, the following "part" represents a "mass part".

<Sample No. 1 production>
[Support]
An aluminum plate made of material 1S having a thickness of 0.30 mm was used with a No. 8 nylon brush and an aqueous suspension of 800 mesh Pamiston, and its surface was grained and washed thoroughly with water. After etching by immersing in 10% sodium hydroxide at 70 ° C. for 60 seconds, washed with running water, neutralized with 20% HNO ₃ and washed with water. This was subjected to an electrolytic surface roughening treatment in a 1% nitric acid aqueous solution with a anodic electricity quantity of 300 coulomb / dm ² using a sinusoidal alternating current under the condition of VA = 12.7V. When the surface roughness was measured, it was 0.45 μm (Ra indication). Next, after dipping in a 30% H ₂ SO ₄ aqueous solution and desmutting at 55 ° C. for 2 minutes, a cathode was placed on the grained surface in 33 ° C., 20% H ₂ SO ₄ aqueous solution to obtain a current density. When anodized at 5 A / dm ² for 50 seconds, the thickness was 2.7 g / m ² .

On the support, the following liquid 1 has a diameter of 118 mm, a roll width of 1450 mm, a surface hard chrome plating, a pitch interval P of the grooved roll P = 0.2 mm, a groove width L = 0.2 mm, and a grooved angle θ = 60 degrees. The liquid was transferred with a grooved pick-up roll at a peripheral speed of 7.0 m / min, and then weighed with a wire bar so that the dry film thickness was 4.5 g / m ² .

・ Liquid 1
Snowtex-S [Nissan Chemical Industry Co., Ltd.] 3.09 parts Snowtex-PSM [Nissan Chemical Industry Co., Ltd. average particle diameter 0.085 μm]
4.55 parts Shilton JC-70 (manufactured by Mizusawa Chemical Co., Ltd., average particle size 4.0 μm) 3.2 parts ETB-300 (manufactured by Titanium Industry Co., Ltd.) 15.14 parts AMT-08 (Mizusawa Chemical Industry Co., Ltd.) 0.83 parts MP-4540 (Nissan Chemical Industries, Ltd.) 3.2 parts Lithium silicate 35 (Nissan Chemical Industries, Ltd.) 1.92 parts Trisodium phosphate, 12 water (Kanto Chemical Co., Ltd.) 0.07 part Pure water 68 part The static surface tension at this time was measured by CBVP-Z manufactured by Kyowa Interface Science Co., Ltd. and was 72 × 10 ⁻⁵ N / cm.

  The sample produced as described above was No. Set to 1.

<Sample No. Production of 2-17>
Samples in which the pick-up roll peripheral speed, pitch interval, groove width, and groove angle were changed were also prepared and evaluated in the same manner. Table 1 shows the changes in each sample.

・ Sample No. 12
Sample No. It is the same sample except that the Snowtex-S of Liquid 1 is 3.03 parts, and 0.06 part of FZ-2161 [Toray Dow Corning Co., Ltd.] is added (Liquid 2).

・ Sample No. 13
Sample No. This is a similar sample except that 3.03 parts of Snowtex-S of No. 3 liquid was added and 0.06 parts of FZ-2161 [Toray Dow Corning Co., Ltd.] was added (Liquid 2).

  For comparison, Sample No. Sample No. 1 in which the pick-up rolls 1 and 12 were changed to flat rolls. 14 and 15 were also evaluated.

  For comparison, Sample No. Sample Nos. 3 and 13 were changed to flat rolls. 16, 17 were also evaluated.

[Evaluation]
<Coating defects>
After coating, the number of omissions per 100 m and 2000 m of sample m ² was counted.

  The larger the number of coating defects, the worse.

<Omitted size>
The size (mm) of the largest missing coating failure per 100 m and 2000 m sample m ² after coating was measured.

<Vertical stripes (application direction stripes)>
The rank per sample m ² of 100 m and 2000 m after coating 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 The following liquid 3 on the above liquid 1 or 2 has a dry film thickness of 0.6 g / provided by bar coating so as to m ^2.

・ Liquid 3
DL-522 [manufactured by Nippon Shokubai Co., Ltd., average molecular weight 170,000] 0.3125 parts HI-DISPER A-118 [manufactured by Gifu Serask Manufacturing Co., Ltd., carnauba wax hot-melt particles, average particle size 0.30 μm] 165 parts SE-2712F [manufactured by Taisei Fine Chemical Co., Ltd., styrene acrylic polymer particles, average particle size of heat-fusible particles 0.06 μm] 1.375 parts Infrared dye (ADS830AT) 0.0975 parts Pure water 89.85 parts Isopropyl Alcohol 5.15 parts Penon JE-66 [manufactured by Nissho Chemical Co., Ltd.] 0.05 parts

  Each sample was evaluated as described below after application of Liquid 3.

<Exposure and printing of planographic printing plate precursor>
Using the obtained lithographic printing plate precursor, a semiconductor laser light source (light emission wavelength: 830 nm, spot size: 10 μm, resolution is 2000 dpi in both the scanning direction and the sub-scanning direction), a 175-line equivalent 50% dot image and a solid image, The exposure was performed 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 Minolta MG Co., Ltd.) as an etchant and HiEcho (Toyo Ink Manufacturing Co., Ltd.) as ink. (Manufactured by Co., Ltd.) and printing was performed using high-quality paper as printing paper.

  Printing was performed in an environment of 23 ° C. and 48% RH.

[Finished print quality]
The following evaluation was performed using a 2000 m sample after the start of coating.

  The finished quality of the 30th sheet after the start of printing was visually evaluated at the following rank.

5: Quality is good 4: Quality is a little inferior, but there is no problem in use 3: Quality is a little inferior, but usable level 2: Poor quality, actual concern level 1: Bad quality, unusable [printing durability]
The following evaluation was performed using a 2000 m sample after the start of coating.

  The number of prints where 50% halftone dots were not reproduced was visually evaluated.

  The larger the number, the higher the printing durability and the better.

  The evaluation results are shown in Table 2.

  From Tables 1 and 2, it can be seen that by satisfying the conditions of the present invention, a sample having sufficiently stable coating properties and good performance is obtained.

It is a schematic block diagram of the pick-up roll system coating device. It is a figure which shows the groove angle, pitch, and groove width of a grooved roll.

Explanation of symbols

1 Pickup roll (Groove roll)
2, 4 Backup roll 3 Scraping roll 5 Coating liquid 6 Groove 10 Support body θ Groove angle

Claims (6)

In a coating method in which a coating liquid is picked up by a pick-up roll, transferred to a substrate, and coated, the static surface tension of the coating liquid is 40 × 10 ^{−5 to} 100 × 10 ⁻⁵ N / cm or more and the pick-up roll is a grooved roll A coating method characterized by the above. 2. The coating method according to claim 1, wherein a pitch interval between the grooves of the pickup roll is 0.1 to 5 mm and a width between the grooves is 0.1 to 1.0 mm. The coating method according to claim 1 or 2, wherein a grooved angle of the pickup roll is 30 to 60 degrees. The coating method according to any one of claims 1 to 3, wherein a peripheral speed of the pickup roll is 1 m / min to 20 m / min. A lithographic printing plate precursor formed by the coating method according to any one of claims 1 to 4. A lithographic printing plate precursor according to claim 5, wherein the lithographic printing plate precursor is subjected to laser exposure based on image information and printed after on-press development.

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