JP2010076336A - Laminated body of original lithographic printing plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laminated body of an original lithographic printing plate capable of performing image-recording and on-press developing by means of infrared laser, having sufficient printing durability and having good sensitivity, on-press developing property and allowable small-dot stains even stored in a layered state. <P>SOLUTION: The laminated body of the original lithographic printing plate is characterized in that the original lithographic printing plate 10 containing (A) an infrared ray absorbent, (B) a radical polymerisation initiator and (C) a polymerisation compound and allowing an image recording layer with a non-exposed part therein to be removed by supplying printing ink and dampening water and an insertion paper 14 with a content of chloride ions ≤0.5 mass% therein, and having 2.4 to 5 μm surface roughness in terms of the center line average roughness (Ra), are layered one on top of the other, on a support body. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a laminate of a lithographic printing plate precursor. More specifically, the present invention relates to a laminate in which lithographic printing plate precursors and slip sheets capable of image recording by laser and on-machine development are alternately stacked.

In general, a lithographic printing plate comprises an oleophilic image area that receives ink in the printing process and a hydrophilic non-image area that receives dampening water. Lithographic printing utilizes the property that water and oil-based inks repel each other, so that the oleophilic image area of the lithographic printing plate is the ink receiving area and the hydrophilic non-image area is dampened with the water receiving area (ink non-receiving area). As described above, a difference in ink adhesion is caused on the surface of a lithographic printing plate, and after ink is applied only to an image portion, the ink is transferred to a printing medium such as paper and printed.
In order to produce this lithographic printing plate, conventionally, a lithographic printing plate precursor (PS plate) in which an oleophilic photosensitive resin layer (image recording layer) is provided on a hydrophilic support has been widely used. Usually, after exposing the lithographic printing plate precursor through an original image such as a lithographic film, the image recording layer corresponding to the image portion remains, and the unnecessary image recording layer corresponding to the non-image portion is removed with an alkaline developer. Alternatively, the lithographic printing plate is obtained by dissolving and removing with an organic solvent-containing developer and exposing the surface of the hydrophilic support to form a non-image portion to form a non-image portion.

  Usually, when packaging a lithographic printing plate precursor using a metal as a support, it is common to stack several to tens of original plates. In this case, the planographic printing plate precursors stacked during handling or transportation may rub against each other and damage the image recording layer. Also, when cutting dozens of lithographic printing plate precursors with a cutting machine called guillotine, the lithographic printing plate precursor alone may damage the guillotine blade during cutting, and the guillotine blade must be replaced frequently. It was.

  Therefore, in order to prevent damage to the lithographic printing plate precursor and damage to the guillotine blade, it is common practice to sandwich a paper called a slip sheet between the lithographic printing plate precursors. Further, thick cardboards called hitting balls are generally provided as cushioning materials on the upper and lower ends of a set of several tens of lithographic printing plate precursors and slip sheets.

  In the conventional plate making process of a lithographic printing plate precursor, a step of dissolving and removing an unnecessary image recording layer with a developer or the like is necessary after exposure. However, such additional wet processing is unnecessary or Simplification is cited as one of the issues. In particular, in recent years, disposal of waste liquids discharged with wet processing has become a major concern for the entire industry due to consideration for the global environment, and therefore, the demand for solving the above-mentioned problems has become stronger.

On the other hand, as one simple plate making method, an image recording layer that can remove an unnecessary portion of the image recording layer in a normal printing process is used. A method called on-press development has been proposed in which unnecessary portions are removed to obtain a lithographic printing plate.
As a specific method of on-press development, for example, a method of using a lithographic printing plate precursor having an image recording layer that can be dissolved or dispersed in dampening water, an ink solvent, or an emulsion of dampening water and ink , A method of mechanically removing the image recording layer by contact with rollers or a blanket of a printing press, cohesion of the image recording layer or adhesion between the image recording layer and the support by penetration of dampening water, ink solvent, etc. There is a method in which after the force is weakened, the image recording layer is mechanically removed by contact with rollers or a blanket.
In the present specification, unless otherwise specified, the “development processing step” means using a device other than a printing machine (usually an automatic developing machine) and contacting a liquid (usually an alkaline developer). Refers to the process of removing the image recording layer of the unexposed portion of the lithographic printing plate precursor and exposing the surface of the hydrophilic support. “On-press development” refers to a liquid (usually printing) using a printing press. Ink and / or fountain solution) refers to a method and a process for removing the image recording layer of the unexposed portion of the lithographic printing plate precursor and exposing the hydrophilic support surface.

  On the other hand, in recent years, digitization technology for electronically processing, storing, and outputting image information by a computer has become widespread, and various new image output methods corresponding to such digitization technology will be put into practical use. It is becoming. Along with this, digitized image information is carried by high-convergence radiation such as laser light, and the lithographic printing plate precursor is scanned and exposed with that light, directly without using a lithographic film. Computer-to-plate technology for manufacturing is attracting attention. Therefore, obtaining a lithographic printing plate precursor adapted to such a technique is one of the important technical issues.

In the simplification of the plate-making work as described above, a system using an image recording layer and a light source that can be handled in a bright room or under a yellow light is preferable from the viewpoint of ease of work.
As such a laser light source, a solid-state laser such as a semiconductor laser and a YAG laser that emits infrared light having a wavelength of 760 to 1200 nm is extremely useful because a high-power and small-sized laser can be obtained at low cost. . A UV laser can also be used.

As an on-press development type lithographic printing plate precursor for recording an image with an infrared laser, for example, Patent Document 1 discloses that an image forming layer in which hydrophobic thermoplastic polymer particles are dispersed in a hydrophilic binder is hydrophilic. A lithographic printing plate precursor provided on a support is described. In this Patent Document 1, the above lithographic printing plate precursor is exposed by an infrared laser, and the hydrophobic thermoplastic polymer particles are coalesced by heat to form an image, which is then mounted on a cylinder of a printing press and moistened. It is described that it is possible to perform on-press development with water and / or ink.
As described above, the method of forming an image by merging the fine particles by simple thermal fusion has a problem that the image strength is extremely weak and the printing durability is insufficient, although it exhibits good on-press developability. .

Patent Documents 2 and 3 describe lithographic printing plate precursors containing microcapsules encapsulating a polymerizable compound on a hydrophilic support.
Furthermore, Patent Document 4 describes a lithographic printing plate precursor in which an image recording layer containing an infrared absorber, a radical polymerization initiator, and a polymerizable compound is provided on a support.

As described above, the method using the polymerization reaction has a feature that the image strength is relatively good because the chemical bond density of the image portion is higher than that of the image portion formed by thermal fusion of the polymer fine particles. When lithographic printing plate precursors are stacked and stored via interleaving paper, sensitivity and on-press developability may be deteriorated, and minute spot-like stains may be generated.
Japanese Patent No. 2938397 JP 2001-277740 A JP 2001-277742 A JP 2002-287334 A

  Accordingly, an object of the present invention is to provide a planographic plate that can be developed on-press, has sufficient printing durability, and has good sensitivity, on-press developability, and fine spot-like stains even when stored in a laminated state. It is to provide a laminate of a printing plate precursor.

1. (A) Infrared absorber, (B) radical polymerization initiator, and (C) polymerizable compound are contained on the support, and printing ink and dampening water are supplied to remove unexposed portions. A lithographic printing plate precursor having an image recording layer that can be formed, and a slip sheet having a chloride ion content of 0.5% by mass or less and a center line average roughness (Ra) of 2.4 μm to 5 μm in the slip sheet A laminate of lithographic printing plate precursors, characterized in that and are alternately stacked and accumulated.
2. The laminate of a lithographic printing plate precursor according to claim 1, wherein the calcium content in the slip sheet is 0.15% by mass to 0.5% by mass.
3. Stack of lithographic printing plate precursor as described in 1 or 2, characterized in that the basis weight of the interleaving paper is ^{40g / m 2 ~55g / m 2} .
4). 4. The laminate of a lithographic printing plate precursor as described in any one of 1 to 3 above, wherein the image recording layer further contains a microcapsule or a microgel.
5). The lithographic printing plate precursor as described in any one of 1 to 4 above, wherein the lithographic printing plate precursor has a protective layer on an image recording layer.
6). The image recording layer contains at least one low-molecular compound selected from the group consisting of polyols, alkyl sulfates, alkyl sulfonates, and betaines. A laminate of the lithographic printing plate precursor as described.
7). The laminate of a lithographic printing plate precursor as described in any one of 1 to 6 above, wherein the lithographic printing plate precursor has an undercoat layer between the support and the image recording layer.

In the present invention, the centerline average roughness (Ra) of a slip sheet used for an on-press developable lithographic printing plate precursor using radical polymerization for image formation is 2.4 μm to 5 μm, and the chloride ion content is Is a laminate of a lithographic printing plate precursor having excellent printing durability, good sensitivity and on-press developability even when aged, and little occurrence of minute spot-like stains. Made it possible to get.
This mechanism of action of the present invention is not necessarily clear, but is estimated as follows.
As described above, the problem of insufficient printing durability in an on-press development type printing plate using heat fusion for image formation can be improved by using a radical polymerization type image recording layer. This type of lithographic printing plate precursor When the laminated body in which the paper was alternately laminated with the interleaving paper was aged, the sensitivity and on-press developability deteriorated, and the problem that minute spot-like stains were generated was left.
This decrease in sensitivity after storage of the laminate is due to the gradual decomposition and decomposition of the polymerization initiator necessary for radical polymerization, as the components containing chloride ions in the slip sheet gradually move and penetrate into the image recording layer during storage of the laminate. Therefore, it is considered that the starting efficiency at the time of image exposure is lowered.
Similarly, for minute spot-like stains, it is considered that when chloride ions reach the surface of the support, the support is locally corroded, and this part cannot be developed on the machine.
Regarding on-press developability deterioration, the hydrophilic low-molecular compound used in the image recording layer for imparting on-press developability moves to the slip sheet during storage, and the image record layer becomes hydrophobic, and the on-press developability This is thought to be due to a decrease in the penetration of dampening water necessary for development.
Therefore, the center line average roughness (Ra) of the interleaf used for the on-press developable lithographic printing plate precursor using radical polymerization for image formation, which is a feature of the present invention, is 2.4 μm to 5 μm, By setting the chloride ion content to 0.5% by mass or less, the lithographic printing plate precursor and the slip sheet are close to point contact even when the laminated body in which the master plate and the slip sheet are alternately stacked is stored over time. Therefore, mass transfer is less likely to occur, less chloride ions permeate into the image recording layer, and less loss of hydrophilic low molecular weight compounds in the image recording layer. We believe that we were able to suppress deterioration and prevent the occurrence of minute spot-like stains.

  According to the present invention, a lithographic printing plate that can be developed on-press, has sufficient printing durability, and has good sensitivity, on-press developability, and fine spot-like stains even when stored in a laminated state. An original laminate can be provided.

[Laminate of planographic printing plate precursor]
The laminate of the lithographic printing plate precursor according to the invention is formed by alternately stacking lithographic printing plate precursors and slip sheets. This laminate is shipped, transported, and stored in a packaged form.
The lithographic printing plate precursor packaging structure for making the laminate into a packaging form may or may not have a contact ball and interior paper. In addition to normal cardboard box packaging, the lithographic printing plate is placed on the skid. Also included are skid-type packaging in which the original laminate is placed and packaged, and paper pallet-type packaging in which the laminate is placed and packaged on a paper pallet.
Hereinafter, specific examples of the planographic printing plate precursor packaging structure will be described with reference to the drawings.

As shown in FIG. 1, the planographic printing plate precursor packaging structure 18 is a laminate formed by alternately laminating interleaving papers 14 and planographic printing plate precursors 10, and further placing contact balls 22 on the upper and lower surfaces. Twelve.
The laminate 12 is wrapped with an interior paper 16 having a moisture-proof effect.
The number of lithographic printing plate precursors 10 constituting one laminate 12 is not particularly limited, but is preferably 10 to 100, for example, from the viewpoints of transportation and storage efficiency, ease of mounting on an automatic plate making machine, and the like. . When the laminate 12 is composed of 10 to 100 lithographic printing plate precursors 10, the lithographic printing plate precursor 10 and the contact balls 22 are fixed by a fixing means such as an adhesive tape so as not to be displaced from each other. It is preferable. Further, the laminated bundle 12 may be constituted by several thousand lithographic printing plate precursors 10. In the laminate 12, the contact balls 22 may be inserted for every 20 to 100 lithographic printing plate precursors 10, or the contact balls 22 may be arranged only above and below the laminate 12.
Further, the contact ball 22 can be omitted in any of the laminated bodies 12.

After wrapping the laminated body 12 thus configured with the interior paper 16, the adhesive paper 24 is used to prevent the interior paper 16 from unintentionally spreading or dropping off, as shown in FIG. A lithographic printing plate precursor packaging structure 18 is configured by fixing the folding portion. Thus, the planographic printing plate precursor 10 is reliably shielded from light and moisture by the interior paper 16.
The planographic printing plate precursor packaging structure 18 may be housed in an exterior box and packaged or loaded on a pallet as necessary.

[Interleaf]
The slip sheet used in the present invention has a center line average roughness (Ra) of 2.4 μm to 5 μm, and the content of chloride ions is 0.5% by mass or less based on the entire slip sheet. is required. A more preferable chloride ion content is 0.3% by mass or less, and further preferably 0.1% by mass or less. When chloride ions are used as a bleaching agent, at least 0.03% by mass of chloride ions remain.
More preferably, the center line average roughness (Ra) is 2.4 μm to 4.0 μm, and more preferably 2.6 μm to 3.5 μm.

As the material of the slip paper used in the present invention, it is preferable to select a low-cost raw material in order to reduce material costs. For example, paper using 100% by mass of wood pulp, or synthetic pulp together with wood pulp And a paper having a low density or high density polyethylene layer provided on the surface thereof can be used. In particular, a paper that does not use a synthetic pulp or a polyethylene layer has a low material cost, so that a slip sheet can be produced at a low cost. Specifically, the bleached kraft pulp is beaten, and the sizing agent is added to the paper stock diluted to a concentration of 4% by weight so that the base paper weight is 0.1% by weight and the paper strength agent is 0.2% by weight. In addition, acidic paper made using a paper stock added with aluminum sulfate until the pH reaches 5.0 can be mentioned. Neutral sizes such as alkyl ketene dimer (AKD) and alkenyl succinic anhydride (ASA) are used as sizing agents. A neutral paper having a pH of 7 to 8 using calcium carbonate as a filler instead of aluminum sulfate is preferably used.
In general, the papermaking process mainly consists of a wire part that uses a wire (net) to dehydrate from a pulp-based material, a press part that further dewaters by pressurization to increase density and wet paper strength, and heats to evaporate water. It consists of four steps of calendering that increases the density, smoothness, and gloss by the dryer part, compression by the roll, and friction.

In such a papermaking process, the center line average roughness (Ra) of the paper depends largely on the raw pulp type and the degree of beating, but largely depends on the calendering process in the papermaking process. The roll material used in calendering, hardness, surface roughness, nip pressure, temperature, and number of nips are the main parameters to adjust the paper smoothness, thereby determining the centerline average roughness.
Further, chloride ions in the interleaving paper are mainly mixed in the step of bleaching the raw material pulp.

  The centerline average roughness Ra in the present invention is a three-dimensional roughness measurement measured under the condition of 23 ° C. and 48% relative humidity after the sample to be measured is left for 24 hours at 23 ° C. and 48% of relative humidity. The center line average roughness Ra is defined by JIS surface roughness JIS-B-0601.

  The centerline average roughness (Ra) by the three-dimensional roughness measurement according to the present invention is a sampling length of 0.5 mm, and M points in the X direction, N points in the Y direction, and a total height measurement at the MN point. Then, a roughness curved surface with the height of the roughness center plane being 0 is obtained, and the height Z at the measurement point of the kth point in the X direction and the jth point in the Y direction is defined as f (Zjk) according to the following equation. The value obtained is expressed in micrometers (μm).

  As a measuring apparatus capable of measuring the center line average roughness (Ra) by the three-dimensional roughness measurement, for example, a RSTPLUS non-contact three-dimensional micro surface shape measuring system manufactured by WYKO can be exemplified.

The method for measuring the chloride ion content by ion chromatography in the present invention will be described below.
The ion chromatographic method is a method for quantifying the concentration of various ions present in an aqueous solution as defined in JIS-K-0127 “General Rules for Ion Chromatograph Analysis”. In the present invention, it is necessary to first extract chloride ions in the slip sheet with water. Specifically, the interleaving paper to be measured is cut into a size of 30 cm × 30 cm, and this is weighed with a precision balance to obtain its mass Wg, and then immersed in 1000 g of pure water, sealed, and subjected to ultrasonic cleaning. A sample aqueous solution from which chloride ions have been extracted is prepared for 2 hours. This is measured by ion chromatography, and the chloride ion concentration C [mass ppm] in the sample aqueous solution is obtained from the peak area using a calibration curve prepared in advance. The chloride ion content of the present invention is determined from the following equation.

The interleaving paper used in the present invention preferably has a calcium content of 0.15% by mass to 0.5% by mass with respect to the entire interleaving paper. The calcium content of the slip sheet can be obtained by measuring the slip sheet with fluorescent X-rays. The effect of this invention improves further by being 0.15 mass% or more. More preferably, it is 0.2 mass%-0.45 mass%, More preferably, it is 0.25 mass%-0.4 mass%.
Calcium contained in paper is mainly calcium carbonate that is widely used as a filler for neutral paper, and has the effect of increasing the whiteness of the paper. In the present invention, if calcium carbonate is used, the whiteness can be improved, so the amount of bleaching agent used as a chloride ion source can be reduced, and since calcium carbonate is a pigment, it is estimated that the mechanism of the present invention is effective. This is thought to contribute to point contact between the lithographic printing plate precursor and the slip sheet.
Within the range of the calcium content, the effects of the present invention can be satisfactorily exhibited.

The basis weight of the interleaf paper used in the present invention (according to defined measurement method in JIS P8124) ^is preferably ^{40g / m 2 ~55g / m 2} .
The basis weight of the interleaf paper is generally a 29~60g / ^{m 2,} the range is preferably Among them, more preferably from ^{45g / m 2 ~50g / m 2} . By making the basis weight 40 g / m ² or more, the effect of the present invention is further improved. When the basis weight is large, the thickness or density of the paper is high, that is, the rigidity as the paper is increased, and the effect of the surface roughness is likely to be exhibited and the point contact is likely to occur.
The pH of the slip sheet used in the present invention is measured by a cold water extraction method defined in JIS P8133.

Other physical properties of the slip sheet are described below.
The thickness (according to the measuring method defined in JIS P 8118) is preferably 42 to 80 μm, more preferably 45 to 65 μm, and still more preferably 45 to 55 μm.
As chemical requirements, a sample of 20 g is cut into 100 g of pure water, sealed and heated at 110 ° C. for 10 minutes, and then no NH ₃ gas is detected by the NH ₃ gas detection method using a Kitagawa gas detector tube (for 20 ppm). Such slip sheets are preferred.
Further, regarding the mechanical and strength characteristics, the preferable requirements for the slip sheet are shown in Table 1 together with the above-described filling degree and chemical requirements, but are not limited thereto.

The notes in the measurement method column of Table 1 are as follows.
(Note 1) The difference between the maximum value and the minimum value obtained by measuring the thickness of an arbitrary position of one sheet in accordance with JIS P 8118.
(Note 2) When the dimension (A) dried for 1 hour at 110 ° C. and the dimension (B) left for 3 hours at 20 ° C. and 65% RH, “stretch degree (rate) = (B · A) / Expansion rate represented by “A × 100”.
(Note 3) The slip sheet is cut into a 150 mm × 150 mm sheet, and this sheet is left in an environment of a temperature of 20 ° C. and a humidity of 65% RH for 3 hours or more. The volume resistance value (Rv) is measured by a capacitive universal electrometer (MMAI 17 and P-601), and the product of the volume resistance value (Rv) and the electrode area (19.62 cm ² ) of the measuring device. Volume specific resistance value (ρv) obtained from the relationship of ρv = 19.62 / t × Rv by removing the slip sheet thickness (t) from
(Note 4) The slip sheet is cut into a 150 mm × 150 mm sheet, and this sheet is left in an environment of a temperature of 20 ° C. and a humidity of 65% RH for 3 hours or more. The surface resistance value was measured by a capacitive universal electrometer (MMAII · 17 and P · 601). Surface specific resistance value (ρs) obtained by ρs = 18.7 × Rs from the product of the surface resistance value (Rs) and a coefficient (18.7) calculated from the electrode area of the measuring instrument.
(Note 5) Static friction coefficient with the image forming surface of a lithographic printing plate.
(Note 6) A value measured with a Kitagawa type gas detector tube (for 20 ppm) after cutting 20 g of a sample into 100 g of pure water and heating at 110 ° C. for 10 minutes.

[Hitball]
The contact ball is formed in a size substantially equal to the upper surface (or lower surface) of the lithographic printing plate precursor group, and prevents the lithographic printing plate precursor from being bent, deformed or damaged by an external force. As the batting ball, a basis weight of 200 to 1500 g / m ² using a single pulp or a mixture of synthetic pulp obtained from linear fibers such as wood pulp, hemp and other linear fibers, polyolefin, etc., regenerated cellulose and the like. A paper having a density of 0.7 to 0.85 g / cm ³ , a Beck smoothness of 3 to 20 seconds, and a pH of 4 to 6 can be used, but is not limited thereto. In particular, it can be manufactured at a low cost by selecting a low-cost material such as wood pulp or natural fiber. More specifically, for example, the raw material waste paper is beaten and diluted to a concentration of 4% by mass with the sizing agent being 0.1% by mass of the cardboard mass and the paper strength agent being 0.2% by mass of the cardboard mass. In addition, a density of 0.72 g / cm ³ and a basis weight of 640 g / m ² obtained by paper making using a paper material in which aluminum sulfate is further added until the pH becomes 5.0 can be mentioned. Of course, it is not limited to this.

  As the contact ball, it is particularly preferable that at least one surface is made of a resin layer or a resin mixed layer. For example, a resin may be coated or laminated on one or both sides of a substrate made of paper, a resin film, a metal film, or the like, or a resin film or a paper mixed with a resin may be bonded. Further, it may be in the form of a film composed of the same resin layer, in the form of a film composed of a single layer of resin mixed paper, or in the form of multiple layers. Further, synthetic paper mainly composed of polyolefin may be used. The moisture content of the contact ball is measured by the measurement method described in JIS P8127.

  Any resin can be used as the resin used for the contact ball used in the present invention. For example, polyethylene, polypropylene, styrene resin, vinyl chloride resin, vinylidene chloride resin, polyvinyl alcohol, acrylic resin, acrylonitrile styrene resin, ethylene vinyl acetate copolymer resin, ABS resin, cellulose derivative resin, polyurethane resin, polyvinyl butyral resin, polyester resin , Epoxy resin, urea resin, melamine resin, silicone resin, fluorine resin, polycarbonate, polyamide resin, polyacetal resin, polybutylene terephthalate, polyethylene terephthalate, polyphenylene sulfide, polysulfone, polyethersulfone, polyarylate, polyetherketone, polyimide resin And other thermoplastic resins. The ratio of the resin to the total of the resin and paper of the contact ball of the present invention is usually 5 to 80% by mass, preferably 10 to 60% by mass. The hitting ball may be inserted as described in Japanese Patent Application Laid-Open No. 2001-315858.

[Lithographic printing plate precursor]
The lithographic printing plate precursor according to the invention has a radical polymerization type image recording layer on a support and can be developed on-press by supplying printing ink and fountain solution.

(Image recording layer)
First, the constituent components of the image recording layer, which is a feature of the present invention, will be described in detail.
The image recording layer used in the present invention is a radically polymerizable image recording layer that can be cured by radical polymerization, and after exposure, the printing ink and fountain solution are supplied on the printing machine to remove unexposed portions. Thus, the image recording layer can form an image. The image recording layer used in the present invention contains (A) an infrared absorber, (B) a radical polymerization initiator, and (C) a polymerizable compound.
Below, each component contained in an image recording layer is demonstrated sequentially.

<(A) Infrared absorber>
The infrared absorbent used in the present invention has a function of converting absorbed infrared light into heat, and a function of being excited by infrared light and transferring electrons and / or energy to a radical polymerization initiator described later. The infrared absorber used in the present invention is a dye or pigment having an absorption maximum at a wavelength of 760 to 1200 nm.

As the dye, commercially available dyes and known dyes described in documents such as “Dye Handbook” (edited by the Society for Synthetic Organic Chemistry, published in 1970) can be used. Specifically, dyes such as azo dyes, metal complex azo dyes, pyrazolone azo dyes, naphthoquinone dyes, anthraquinone dyes, phthalocyanine dyes, carbonium dyes, quinoneimine dyes, methine dyes, cyanine dyes, squarylium dyes, pyrylium salts, metal thiolate complexes, etc. Is mentioned.
Preferred dyes include, for example, cyanine dyes described in JP-A-58-125246, JP-A-59-84356, JP-A-60-78787, JP-A-58-173696, The methine dyes described in Japanese Laid-Open Patent Publication Nos. 58-181690 and 58-194595, Japanese Patent Laid-Open Nos. 58-112793, 58-224793, 59-48187, Naphthoquinone dyes described in JP-A-59-73996, JP-A-60-52940, JP-A-60-63744, and the like, squarylium dyes described in JP-A-58-112792, and the like; And cyanine dyes described in British Patent No. 434,875.

Further, a near infrared absorption sensitizer described in US Pat. No. 5,156,938 is also preferably used, and a substituted arylbenzo (thio) described in US Pat. No. 3,881,924 is also preferred. ) Pyrylium salt, trimethine thiapyrylium salt described in JP-A-57-142645 (US Pat. No. 4,327,169), JP-A-58-181051, 58-220143, 59- No. 41363, 59-84248, 59-84249, 59-146063, 59-146061, and pyrine compounds described in JP-A-59-216146. And pentamethine thiopyrylium salts described in US Pat. No. 4,283,475, and Japanese Patent Publication Nos. 5-13514 and 5-19702. Pyrylium compounds shown also preferably used. Another example of a preferable dye is a near-infrared absorbing dye described in US Pat. No. 4,756,993 as formulas (I) and (II).
In the present invention, other preferred examples of infrared absorbing dyes include specific indolenine cyanine dyes described in JP-A-2002-278057 as exemplified below.

  Among these dyes, cyanine dyes, squarylium dyes, pyrylium salts, nickel thiolate complexes, and indolenine cyanine dyes are preferable. Further, cyanine dyes and indolenine cyanine dyes are preferable, and one particularly preferable example is a cyanine dye represented by the following general formula (i).

In formula (i), X ¹ represents a hydrogen atom, a halogen atom, -NPh ^_2, -X ₂ -L ¹ or a group represented by the following structural formula. Here, X ² represents an oxygen atom, a nitrogen atom, or a sulfur atom, and L ¹ represents a hydrocarbon group having 1 to 12 carbon atoms, an aromatic ring having a hetero atom, or 1 to 1 carbon atom containing a hetero atom. 12 hydrocarbon groups are shown. In addition, a hetero atom here shows a nitrogen atom, a sulfur atom, an oxygen atom, a halogen atom, and a selenium atom. R ^a represents a hydrogen atom, an alkyl group, an aryl group, a substituted or unsubstituted amino group, a substituted amino group and a halogen atom, X _a ^- is Z _a to be described later ^- is the same definition.

R ¹ and R ² each independently represents a hydrocarbon group having 1 to 12 carbon atoms. In view of the storage stability of the image recording layer coating solution, R ¹ and R ² are preferably hydrocarbon groups having 2 or more carbon atoms, and R ¹ and R ² are bonded to each other to form a 5-membered member. It is particularly preferable that a ring or a 6-membered ring is formed.

Ar ¹ and Ar ² may be the same or different and each represents an aromatic hydrocarbon group which may have a substituent. Preferred aromatic hydrocarbon groups include a benzene ring and a naphthalene ring. Preferred substituents include a hydrocarbon group having 12 or less carbon atoms, a halogen atom, an alkoxy group having 12 or less carbon atoms, a hydrocarbon group having 12 or less carbon atoms, and 12 carbon atoms. Most preferred are not more than alkoxy groups. Y ¹ and Y ² may be the same or different and each represents a sulfur atom or a dialkylmethylene group having 12 or less carbon atoms. R ³ and R ⁴ may be the same or different and each represents a hydrocarbon group having 20 or less carbon atoms which may have a substituent. Preferable substituents include alkoxy groups having 12 or less carbon atoms, carboxy groups, and sulfo groups, and alkoxy groups having 12 or less carbon atoms are most preferable. R ⁵ , R ⁶ , R ⁷ and R ⁸ may be the same or different and each represents a hydrogen atom or a hydrocarbon group having 12 or less carbon atoms. From the availability of raw materials, a hydrogen atom is preferred. Z _a ^- represents a counter anion. However, when the cyanine dye represented by formula (i) has an anionic substituent in the structure thereof, Z _a is does not require charge neutralization ^- is not necessary. Preferred Z _a ^- is the storage stability of the image recording layer coating solution, the halide ions other than chloride ion, perchlorate ion, a tetrafluoroborate ion, hexafluorophosphate ion, and sulfonate ion, particularly Preferred are perchlorate ion, tetrafluoroborate ion, hexafluorophosphate ion, and aryl sulfonate ion.

Specific examples of cyanine dyes represented by formula (i) that can be suitably used in the present invention include those described in paragraph numbers [0017] to [0019] of JP-A No. 2001-133969. Can do.
Further, other particularly preferable examples include specific indolenine cyanine dyes described in JP-A-2002-278057 described above.

  Examples of the pigment used in the present invention include commercially available pigments and color index (CI) manual, “Latest Pigment Handbook” (edited by Japan Pigment Technology Association, published in 1977), “Latest Pigment Application Technology” (CMC Publishing, 1986), “Printing Ink Technology”, CMC Publishing, 1984) can be used.

  Examples of the pigment include black pigments, yellow pigments, orange pigments, brown pigments, red pigments, purple pigments, blue pigments, green pigments, fluorescent pigments, metal powder pigments, and other polymer-bonded dyes. Specifically, insoluble azo pigments, azo lake pigments, condensed azo pigments, chelate azo pigments, phthalocyanine pigments, anthraquinone pigments, perylene and perinone pigments, thioindigo pigments, quinacridone pigments, dioxazine pigments, isoindolinone pigments In addition, quinophthalone pigments, dyed lake pigments, azine pigments, nitroso pigments, nitro pigments, natural pigments, fluorescent pigments, inorganic pigments, carbon black, and the like can be used. Among these pigments, carbon black is preferable.

  These pigments may be used without surface treatment, or may be used after surface treatment. The surface treatment method includes a method of surface coating with a resin or wax, a method of attaching a surfactant, a method of bonding a reactive substance (eg, silane coupling agent, epoxy compound, polyisocyanate, etc.) to the pigment surface, etc. Can be considered. The above-mentioned surface treatment methods are described in “Characteristics and Applications of Metal Soap” (Yokoshobo), “Printing Ink Technology” (CMC Publishing, 1984) and “Latest Pigment Application Technology” (CMC Publishing, 1986). Yes.

  The particle size of the pigment is preferably in the range of 0.01 μm to 10 μm, more preferably in the range of 0.05 μm to 1 μm, and particularly preferably in the range of 0.1 μm to 1 μm. Within this range, good stability of the pigment dispersion in the coating solution for the image recording layer and good uniformity of the image recording layer can be obtained.

  As a method for dispersing the pigment, a known dispersion technique used for ink production, toner production or the like can be used. Examples of the disperser include an ultrasonic disperser, a sand mill, an attritor, a pearl mill, a super mill, a ball mill, an impeller, a disperser, a KD mill, a colloid mill, a dynatron, a three-roll mill, and a pressure kneader. Details are described in "Latest Pigment Applied Technology" (CMC Publishing, 1986).

These infrared absorbers may be added to the same layer as other components, or may be added to another image recording layer provided. However, when a lithographic printing plate precursor is prepared, image recording is performed. The layer is added so that the absorbance at the maximum absorption wavelength in the wavelength range of 760 nm to 1200 nm is in the range of 0.3 to 1.2 by the reflection measurement method. Preferably, it is the range of 0.4-1.1. Within this range, a uniform polymerization reaction proceeds in the depth direction of the image recording layer, and good film strength of the image area and adhesion to the support can be obtained.
The absorbance of the image recording layer can be adjusted by the amount of infrared absorber added to the image recording layer and the thickness of the image recording layer. The absorbance can be measured by a conventional method. As a measuring method, for example, on a reflective support such as aluminum, an image recording layer having a thickness appropriately determined in a range in which the coating amount after drying is necessary as a lithographic printing plate is formed, and the reflection density is set to the optical density. And a method of measuring with a spectrophotometer by a reflection method using an integrating sphere.

  If the content of the (A) infrared absorber in the image recording layer in the present invention is described in terms of a specific addition amount, 0.1 to 10.0% by mass of the total solid content of the image recording layer is preferable, and more preferable. Is 0.5-5.0 mass%.

<(B) Radical polymerization initiator>
The (B) radical polymerization initiator used in the present invention is a compound that generates radicals by light, heat, or both, and initiates and accelerates polymerization of the polymerizable compound (C). As the radical polymerization initiator that can be used in the present invention, a known thermal polymerization initiator, a compound having a bond with a small bond dissociation energy, a photopolymerization initiator, and the like can be used.
Examples of the radical polymerization initiator in the present invention include (a) an organic halide, (b) a carbonyl compound, (c) an azo polymerization initiator, (d) an organic peroxide, (e) a metallocene compound, (f ) Azide compound, (g) hexaarylbiimidazole compound, (h) organic borate compound, (i) disulfone compound, (j) oxime ester compound, (k) onium salt compound.

  (A) Specific examples of organic halides include Wakabayashi et al., “Bull Chem. Soc Japan” 42, 2924 (1969), US Pat. No. 3,905,815, Japanese Patent Publication No. 46-4605, JP-A 48-36281, JP-A 55-32070, JP-A 60-239736, JP-A 61-169835, JP-A 61-169837, JP-A 62-58241, JP Sho 62-212401, JP-A 63-70243, JP-A 63-298339, M.S. P. Examples include compounds described in Hutt “Journal of Heterocyclic Chemistry” 1 (No 3), (1970) ”, and particularly preferable examples include oxazole compounds substituted with a trihalomethyl group and s-triazine compounds.

  More preferred are s-triazine derivatives and oxadiazole derivatives to which at least one mono, di, or trihalogen-substituted methyl group is bonded. Specifically, for example, 2,4,6-tris (monochloromethyl) -s-triazine, 2,4,6-tris (dichloromethyl) -s-triazine, 2,4,6-tris (trichloromethyl) -S-triazine, 2-methyl-4,6-bis (trichloromethyl) -s-triazine, 2-n-propyl-4,6-bis (trichloromethyl) -s-triazine, 2- (α, α, β-trichloroethyl) -4,6-bis (trichloromethyl) -s-triazine, 2-phenyl-4,6-bis (trichloromethyl) -s-triazine, 2- (p-methoxyphenyl) -4,6 -Bis (trichloromethyl) -s-triazine, 2- (3,4-epoxyphenyl) -4,6-bis (trichloromethyl) -s-triazine, 2- (p-chlorophenyl) -4,6- (Trichloromethyl) -s-triazine, 2- (p-bromophenyl) -4,6-bis (trichloromethyl) -s-triazine, 2- (p-fluorophenyl) -4,6-bis (trichloromethyl) ) -S-triazine, 2- (p-trifluoromethylphenyl) -4,6-bis (trichloromethyl) -s-triazine, 2- (2,6-dichlorophenyl) -4,6-bis (trichloromethyl) -S-triazine, 2- (2,6-difluorophenyl) -4,6-bis (trichloromethyl) -s-triazine, 2- (2,6-dibromophenyl) -4,6-bis (trichloromethyl) -S-triazine, 2- (4-biphenylyl) -4,6-bis (trichloromethyl) -s-triazine, 2- (4'-chloro-4-biphenylyl) -4,6 Bis (trichloromethyl) -s-triazine, 2- (p-cyanophenyl) -4,6-bis (trichloromethyl) -s-triazine, 2- (p-acetylphenyl) -4,6-bis (trichloromethyl) ) -S-triazine, 2- (p-ethoxycarbonylphenyl) -4,6-bis (trichloromethyl) -s-triazine, 2- (p-phenoxycarbonylphenyl) -4,6-bis (trichloromethyl)- s-triazine, 2- (p-methylsulfonylphenyl) -4,6-bis (trichloromethyl) -s-triazine, 2- (p-dimethylsulfoniumphenyl) -4,6-bis (trichloromethyl) -s- Triazine tetrafluoroborate, 2- (2,4-difluorophenyl) -4,6-bis (trichloromethyl) -s-tria Gin, 2- (p-diethoxyphosphorylphenyl) -4,6-bis (trichloromethyl) -s-triazine, 2- [4- (4-hydroxyphenylcarbonylamino) phenyl] -4,6-bis (trichloro) Methyl) -s-triazine, 2- [4- (p-methoxyphenyl) -1,3-butadienyl] -4,6-bis (trichloromethyl) -s-triazine, 2-styryl-4,6-bis ( Trichloromethyl) -s-triazine, 2- (p-methoxystyryl) -4,6-bis (trichloromethyl) -s-triazine, 2- (pi-propyloxystyryl) -4, 6-bis (trichloro) Methyl) -s-triazine, 2- (p-tolyl) -4,6-bis (trichloromethyl) -s-triazine, 2- (4-methoxynaphthyl) -4,6-bi (Trichloromethyl) -s-triazine, 2-phenylthio-4,6-bis (trichloromethyl) -s-triazine, 2-benzylthio-4,6-bis (trichloromethyl) -s-triazine, 2,4,6 -Tris (dibromomethyl) -s-triazine, 2,4,6-tris (tribromomethyl) -s-triazine, 2-methyl-4,6-bis (tribromomethyl) -s-triazine, 2-methoxy -4,6-bis (tribromomethyl) -s-triazine, 2- (o-methoxystyryl) -5-trichloromethyl-1,3,4-oxadiazole, 2- (3,4-epoxystyryl) -5-trichloromethyl-1,3,4-oxadiazole, 2- [1-phenyl-2- (4-methoxyphenyl) vinyl] -5-trichloromethyl-1,3 4-oxadiazole, 2- (p-hydroxystyryl) -5-trichloromethyl-1,3,4-oxadiazole, 2- (3,4-dihydroxystyryl) -5-trichloromethyl-1,3 4-oxadiazole, 2- (pt-butoxystyryl) -5-trichloromethyl-1,3,4-oxadiazole and the like.

  (B) Examples of the carbonyl compound include benzophenone, Michler ketone, 2-methylbenzophenone, 3-methylbenzophenone, 4-methylbenzophenone, 2-chlorobenzophenone, 4-bromobenzophenone, 2-carboxybenzophenone and other benzophenone derivatives, 2,2- Dimethoxy-2-phenylacetophenone, 2,2-diethoxyacetophenone, 1-hydroxycyclohexyl phenylketone, α-hydroxy-2-methylphenylpropanone, 1-hydroxy-1-methylethyl- (p-isopropylphenyl) ketone, 1-hydroxy-1- (p-dodecylphenyl) ketone, 2-methyl- (4 ′-(methylthio) phenyl) -2-morpholino-1-propanone, 1,1,1-trichloromethyl- (p-butylphenol) E) Acetophenone derivatives such as ketone, thioxanthone derivatives such as thioxanthone, 2-ethylthioxanthone, 2-isopropylthioxanthone, 2-chlorothioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, 2,4-diisopropylthioxanthone, Examples thereof include benzoic acid ester derivatives such as ethyl p-dimethylaminobenzoate and ethyl p-diethylaminobenzoate.

  (C) As the azo compound, for example, an azo compound described in JP-A-8-108621 can be used.

  (D) Examples of the organic peroxide include trimethylcyclohexanone peroxide, acetylacetone peroxide, 1,1-bis (tert-butylperoxy) -3,3,5-trimethylcyclohexane, 1,1-bis (tert -Butylperoxy) cyclohexane, 2,2-bis (tert-butylperoxy) butane, tert-butyl hydroperoxide, cumene hydroperoxide, diisopropylbenzene hydroperoxide, 2,5-dimethylhexane-2,5- Dihydroperoxide, 1,1,3,3-tetramethylbutyl hydroperoxide, tert-butylcumyl peroxide, dicumyl peroxide, 2,5-dimethyl-2,5-di (tert-butylperoxy) Hexane, 2 5-Oxanoyl peroxide, succinic peroxide, benzoyl peroxide, 2,4-dichlorobenzoyl peroxide, diisopropyl peroxydicarbonate, di-2-ethylhexyl peroxydicarbonate, di-2-ethoxyethyl peroxydi Carbonate, dimethoxyisopropylperoxycarbonate, di (3-methyl-3-methoxybutyl) peroxydicarbonate, tert-butylperoxyacetate, tert-butylperoxypivalate, tert-butylperoxyneodecanoate, tert -Butyl peroxyoctanoate, tert-butyl peroxylaurate, tersyl carbonate, 3,3 ', 4,4'-tetra- (t-butylperoxycarbonyl) benzophenone, 3,3', 4 4′-tetra- (t-hexylperoxycarbonyl) benzophenone, 3,3 ′, 4,4′-tetra- (p-isopropylcumylperoxycarbonyl) benzophenone, carbonyldi (t-butylperoxydihydrogen diphthalate ), Carbonyldi (t-hexylperoxydihydrogen diphthalate), and the like.

  (E) As metallocene compounds, JP-A-59-152396, JP-A-61-151197, JP-A-63-41484, JP-A-2-249, JP-A-2-4705 Various titanocene compounds described in JP-A-5-83588, for example, di-cyclopentadienyl-Ti-bis-phenyl, di-cyclopentadienyl-Ti-bis-2,6-difluorophen-1- , Di-cyclopentadienyl-Ti-bis-2,4-di-fluorophen-1-yl, di-cyclopentadienyl-Ti-bis-2,4,6-trifluorophen-1-yl , Di-cyclopentadienyl-Ti-bis-2,3,5,6-tetrafluorophen-1-yl, di-cyclopentadienyl-Ti-bis-2,3,4,5,6-pen Fluorophen-1-yl, di-methylcyclopentadienyl-Ti-bis-2,6-difluorophen-1-yl, di-methylcyclopentadienyl-Ti-bis-2,4,6-trifluoro Phen-1-yl, di-methylcyclopentadienyl-Ti-bis-2,3,5,6-tetrafluorophen-1-yl, di-methylcyclopentadienyl-Ti-bis-2,3 4,5,6-pentafluorophen-1-yl, di-cyclopentadienyl-Ti-bis-2,6-difluoro-3- (pyrrol-1-yl) phen-1-yl, Examples thereof include iron-arene complexes described in 304453 and JP-A-1-152109.

(F) Examples of the azide compound include 2,6-bis (4-azidobenzylidene) -4-methylcyclohexanone.
(G) Examples of hexaarylbiimidazole compounds include JP-B-6-29285, U.S. Pat. Nos. 3,479,185, 4,311,783, and 4,622,286. Various compounds described in the specification, specifically 2,2′-bis (o-chlorophenyl) -4,4 ′, 5,5′-tetraphenylbiimidazole, 2,2′-bis (o- Bromophenyl)) 4,4 ′, 5,5′-tetraphenylbiimidazole, 2,2′-bis (o, p-dichlorophenyl) -4,4 ′, 5,5′-tetraphenylbiimidazole, 2, 2'-bis (o-chlorophenyl) -4,4 ', 5,5'-tetrakis (m-methoxyphenyl) biidazole, 2,2'-bis (o, o'-dichlorophenyl) -4,4', 5 , 5'-tetraphenylbiimidazole, 2 , 2′-bis (o-nitrophenyl) -4,4 ′, 5,5′-tetraphenylbiimidazole, 2,2′-bis (o-methylphenyl) -4,4 ′, 5,5′- Examples include tetraphenylbiimidazole and 2,2′-bis (o-trifluorophenyl) -4,4 ′, 5,5′-tetraphenylbiimidazole.

  (H) Examples of the organic borate compound include JP-A-62-143044, JP-A-62-1050242, JP-A-9-188865, JP-A-9-188686, JP-A-9-188710, JP 2000-131837, JP 2002-107916, JP 2764769, JP 2002-116539, and Kunz, Martin “Rad Tech '98. Proceeding April 19-22, 1998, Chicago”. Organoboron salts described in JP-A-6-157623, JP-A-6-175564, JP-A-6-175561, and organic boron oxosulfonium complexes described in JP-A-6-157563, JP-A-175554, JP-A-6-1755 No. 3, an organoboron iodonium complex, an organoboron phosphonium complex described in JP-A-9-188710, JP-A-6-348011, JP-A-7-128785, JP-A-7-140589, Specific examples include organoboron transition metal coordination complexes such as JP-A-7-306527 and JP-A-7-292014.

  (I) Examples of the disulfone compound include compounds described in JP-A Nos. 61-166544 and 2003-328465.

  (J) Examples of the oxime ester compound include J.M. C. S. Perkin II (1979) 1653-1660), J. MoI. C. S. Examples include Perkin II (1979) 156-162, Journal of Photopolymer Science and Technology (1995) 202-232, JP-A 2000-66385, and JP-A 2000-80068. Specific examples thereof include compounds represented by the following structural formula.

  (K) Examples of the onium salt compounds include S.I. I. Schlesinger, Photogr. Sci. Eng. , 18, 387 (1974), T.A. S. Diazonium salts described in Bal et al, Polymer, 21, 423 (1980), ammonium salts described in US Pat. No. 4,069,055, JP-A-4-365049, etc., US Pat. No. 4,069 , 055 and 4,069,056, phosphonium salts described in European Patent Nos. 104 and 143, U.S. Pat. Nos. 339,049 and 410,201, 2-150848, JP-A-2-296514, iodonium salts, European Patent Nos. 370,693, 390,214, 233,567, 297,443, and 297,442 U.S. Pat. Nos. 4,933,377, 161,811, 410,201, 339,049, 4,760,013, 4,73 No. 4,444, 2,833,827, German Patent Nos. 2,904,626, 3,604,580, and 3,604,581 . V. Crivello et al, Macromolecules, 10 (6), 1307 (1977), J. MoI. V. Crivello et al, J.A. Polymer Sci. , Polymer Chem. Ed. , 17, 1047 (1979), a selenonium salt described in C.I. S. Wen et al, Teh, Proc. Conf. Rad. Curing ASIA, p478 Tokyo, Oct (1988), and onium salts such as arsonium salts.

In particular, the above oxime ester compounds, diazonium salts, iodonium salts, and sulfonium salts are preferable in terms of reactivity and stability. In the present invention, these onium salts function not as acid generators but as ionic radical polymerization initiators.
Preferred onium salts for the present invention are onium salts represented by the following general formulas (RI-I) to (RI-III).

Formula (RI-I) in, Ar ¹¹ represents a 1-6 having unprotected aryl group having 20 or less carbon atoms is also a substituent, preferred examples of the substituent include an alkyl group having 1 to 12 carbon atoms, 1 to 4 carbon atoms -12 alkenyl group, C1-C12 alkynyl group, C1-C12 aryl group, C1-C12 alkoxy group, C1-C12 aryloxy group, halogen atom, C1-C12 An alkylamino group, a C1-C12 dialkylamino group, a C1-C12 alkylamide group or arylamide group, a carbonyl group, a carboxy group, a cyano group, a sulfonyl group, a C1-C12 thioalkyl group, A C1-C12 thioaryl group is mentioned. Z ^11- represents a monovalent anion, halide ion other than chloride ion, perchlorate ion, hexafluorophosphate ion, tetrafluoroborate ion, sulfonate ion, sulfinate ion, thiosulfonate ion, sulfate ion From the viewpoint of stability and visibility of a printout image, perchlorate ion, hexafluorophosphate ion, tetrafluoroborate ion, sulfonate ion, and sulfinate ion are preferable.

In the formula (RI-II), Ar ²¹ and Ar ²² each independently represent an aryl group having 20 or less carbon atoms which may have 1 to 6 substituents, and preferred substituents have 1 to 12 carbon atoms. An alkyl group, an alkenyl group having 1 to 12 carbon atoms, an alkynyl group having 1 to 12 carbon atoms, an aryl group having 1 to 12 carbon atoms, an alkoxy group having 1 to 12 carbon atoms, an aryloxy group having 1 to 12 carbon atoms, a halogen atom , An alkylamino group having 1 to 12 carbon atoms, a dialkylamino group having 1 to 12 carbon atoms, an alkylamide group or arylamide group having 1 to 12 carbon atoms, a carbonyl group, a carboxy group, a cyano group, a sulfonyl group, 1 carbon atom -12 thioalkyl group and C1-C12 thioaryl group are mentioned. Z ^21- represents a monovalent anion, halide ion other than chloride ion, perchlorate ion, hexafluorophosphate ion, tetrafluoroborate ion, sulfonate ion, sulfinate ion, thiosulfonate ion, sulfate ion From the viewpoint of stability and visibility of a printout image, perchlorate ion, hexafluorophosphate ion, tetrafluoroborate ion, sulfonate ion, sulfinate ion, and carboxylate ion are preferable.

In the formula (RI-III), R ³¹ , R ³² and R ³³ each independently represents an aryl group having 20 or less carbon atoms, an alkyl group, an alkenyl group or an alkynyl group which may have 1 to 6 substituents. In view of reactivity and stability, an aryl group is desirable. Preferred substituents are alkyl groups having 1 to 12 carbon atoms, alkenyl groups having 1 to 12 carbon atoms, alkynyl groups having 1 to 12 carbon atoms, aryl groups having 1 to 12 carbon atoms, alkoxy groups having 1 to 12 carbon atoms, C1-C12 aryloxy group, halogen atom, C1-C12 alkylamino group, C1-C12 dialkylamino group, C1-C12 alkylamide group or arylamide group, carbonyl group, carboxy group Group, a cyano group, a sulfonyl group, a thioalkyl group having 1 to 12 carbon atoms, and a thioaryl group having 1 to 12 carbon atoms. Z ^31- represents a monovalent anion, halide ion other than chloride ion, perchlorate ion, hexafluorophosphate ion, tetrafluoroborate ion, sulfonate ion, sulfinate ion, thiosulfonate ion, sulfate ion In view of stability and visibility of the printout image, perchlorate ion, hexafluorophosphate ion, tetrafluoroborate ion, sulfonate ion, sulfinate ion and carboxylate ion are preferable, and more preferable as JP Carboxylic acid ions described in Japanese Patent Application Laid-Open No. 2001-343742, particularly preferably those described in Japanese Patent Application Laid-Open No. 2002-148790.

  Examples of onium salts that can be suitably used as radical polymerization initiators in the present invention will be given below, but the present invention is not limited thereto.

(B) The radical polymerization initiator is not limited to the above, but particularly from the viewpoint of reactivity and stability, (a) an organic halide, particularly, a triazine-based initiator included therein, (j) oxime Diazonium salts, iodonium salts, and sulfonium salts included in the ester compounds and (k) onium salt compounds are more preferable. Among these radical polymerization initiators, from the viewpoint of improving the visibility of the printout image in combination with an infrared absorber, it is an onium salt and an inorganic anion such as PF ₆ ⁻ , BF as a counter ion. ₄ ^- such as those having preferred. Furthermore, diaryliodonium is preferred as the onium salt because of its excellent color development.

These (B) radical polymerization initiators may be used alone or in combination of two or more.
(B) The radical polymerization initiator is preferably 0.1 to 50% by mass, more preferably 0.5 to 30% by mass, and particularly preferably 0.8 to 20% by mass with respect to the total solid content constituting the image recording layer. % Can be added. Within this range, good sensitivity and good stain resistance of the non-image area during printing can be obtained.
In addition, these (B) radical polymerization initiators may be added to the same layer as other components, or another layer may be provided in or adjacent to the image recording layer. .

<(C) Polymerizable compound>
The polymerizable compound (C) that can be used in the present invention is an addition polymerizable compound having at least one ethylenically unsaturated double bond, and has at least one terminal ethylenically unsaturated bond, preferably two or more. It is preferable to be selected from the compounds having. Such a compound group is widely known in the industrial field, and can be used without any particular limitation in the present invention. These have chemical forms such as monomers, prepolymers, ie dimers, trimers and oligomers, or mixtures thereof and their (co) polymers.

  Examples of monomers and copolymers thereof include unsaturated carboxylic acids (for example, acrylic acid, methacrylic acid, itaconic acid, crotonic acid, isocrotonic acid, maleic acid, etc.), and esters and amides thereof. In this case, an ester of an unsaturated carboxylic acid and an aliphatic polyhydric alcohol compound, or an amide of an unsaturated carboxylic acid and an aliphatic polyvalent amine compound is used. In addition, an addition reaction product of an unsaturated carboxylic acid ester or amide having a nucleophilic substituent such as a hydroxy group, amino group or mercapto group with a monofunctional or polyfunctional isocyanate or epoxy, and monofunctional or polyfunctional A dehydration condensation reaction product with a functional carboxylic acid is also preferably used. Further, an addition reaction product of an unsaturated carboxylic acid ester or amide having an electrophilic substituent such as an epoxy group or an epoxy group with a monofunctional or polyfunctional alcohol, amine or thiol, a halogen group or Also suitable are substitution reaction products of unsaturated carboxylic acid esters or amides having a leaving substituent such as a tosyloxy group with monofunctional or polyfunctional alcohols, amines or thiols. As another example, it is also possible to use a group of compounds substituted with unsaturated phosphonic acid, styrene, vinyl ether or the like instead of the unsaturated carboxylic acid.

  Specific examples of the monomer of an ester of an aliphatic polyhydric alcohol compound and an unsaturated carboxylic acid include acrylic acid esters such as ethylene glycol diacrylate, triethylene glycol diacrylate, 1,3-butanediol diacrylate, and tetramethylene glycol. Diacrylate, propylene glycol diacrylate, neopentyl glycol diacrylate, trimethylolpropane triacrylate, trimethylolpropane tri (acryloyloxypropyl) ether, trimethylolethane triacrylate, hexanediol diacrylate, 1,4-cyclohexanediol diacrylate , Tetraethylene glycol diacrylate, pentaerythritol diacrylate, pentaerythritol triacrylate , Pentaerythritol tetraacrylate, dipentaerythritol diacrylate, dipentaerythritol hexaacrylate, sorbitol triacrylate, sorbitol tetraacrylate, sorbitol pentaacrylate, sorbitol hexaacrylate, tri (acryloyloxyethyl) isocyanurate, isocyanuric acid ethylene oxide (EO) modified Examples include diacrylate, isocyanuric acid EO-modified triacrylate, and polyester acrylate oligomer.

  Methacrylic acid esters include tetramethylene glycol dimethacrylate, triethylene glycol dimethacrylate, neopentyl glycol dimethacrylate, trimethylolpropane trimethacrylate, trimethylolethane trimethacrylate, ethylene glycol dimethacrylate, 1,3-butanediol dimethacrylate, Hexanediol dimethacrylate, pentaerythritol dimethacrylate, pentaerythritol trimethacrylate, pentaerythritol tetramethacrylate, dipentaerythritol dimethacrylate, dipentaerythritol hexamethacrylate, sorbitol trimethacrylate, sorbitol tetramethacrylate, bis [p- (3-methacryloxy- 2-hydroxypro ) Phenyl] dimethyl methane, bis - [p- (methacryloxyethoxy) phenyl] dimethyl methane.

Itaconic acid esters include ethylene glycol diitaconate, propylene glycol diitaconate, 1,3-butanediol diitaconate, 1,4-butanediol diitaconate, tetramethylene glycol diitaconate, pentaerythritol diitaconate And sorbitol tetritaconate.
Examples of crotonic acid esters include ethylene glycol dicrotonate, tetramethylene glycol dicrotonate, pentaerythritol dicrotonate, and sorbitol tetradicrotonate.
Examples of isocrotonic acid esters include ethylene glycol diisocrotonate, pentaerythritol diisocrotonate, and sorbitol tetraisocrotonate.
Examples of maleic acid esters include ethylene glycol dimaleate, triethylene glycol dimaleate, pentaerythritol dimaleate, and sorbitol tetramaleate.

  Examples of other esters include, for example, aliphatic alcohol esters described in JP-B-51-47334 and JP-A-57-196231, JP-A-59-5240, and JP-A-59-5241. And those having an aromatic skeleton described in JP-A-2-226149 and those containing an amino group described in JP-A-1-165613. Furthermore, the ester monomers described above can also be used as a mixture.

  Specific examples of amide monomers of aliphatic polyvalent amine compounds and unsaturated carboxylic acids include methylene bis-acrylamide, methylene bis-methacrylamide, 1,6-hexamethylene bis-acrylamide, 1,6-hexamethylene bis. -Methacrylamide, diethylenetriamine trisacrylamide, xylylene bisacrylamide, xylylene bismethacrylamide and the like. Examples of other preferable amide monomers include those having a cyclohexylene structure described in JP-B-54-21726.

  Further, urethane-based addition polymerizable compounds produced by using an addition reaction of isocyanate and hydroxy group are also suitable. Specific examples of such compounds are described in, for example, Japanese Patent Publication No. 48-41708. Containing two or more polymerizable vinyl groups in one molecule obtained by adding a vinyl monomer containing a hydroxy group represented by the following general formula (ii) to a polyisocyanate compound having two or more isocyanate groups in the molecule A vinyl urethane compound etc. are mentioned.

^{_{CH 2 = C (R 19)}} COOCH 2 CH (R 20) OH formula (ii)
(However, R ¹⁹ and R ²⁰ each represent H or CH _3. )

  Also, urethane acrylates such as those described in JP-A-51-37193, JP-B-2-32293, and JP-B-2-16765, JP-B-58-49860, JP-B-56-17654 And urethane compounds having an ethylene oxide skeleton described in JP-B-62-39417 and JP-B-62-39418. Furthermore, addition polymerizable compounds having an amino structure or a sulfide structure in the molecule described in JP-A-63-277653, JP-A-63-260909, and JP-A-1-105238 are used. Depending on the case, it is possible to obtain a photopolymerizable composition excellent in the photosensitive speed.

  Other examples include polyester acrylates, epoxy resins and acrylic acid or methacrylic acid described in JP-A-48-64183, JP-B-49-43191, JP-B-52-30490, Mention may be made of polyfunctional acrylates and methacrylates such as reacted epoxy acrylates. In addition, JP-B-46-43946, JP-B-1-40337, JP-B-1-40336, specific unsaturated compounds described in each publication, vinylphosphonic acid compounds described in JP-A-2-25493, and the like are also included. Can be mentioned. In some cases, a structure containing a perfluoroalkyl group described in JP-A-61-22048 is preferably used. Furthermore, Journal of Japan Adhesion Association vol. 20, no. 7, pages 300 to 308 (1984) as photocurable monomers and oligomers can also be used.

About these addition polymerizable compounds, the details of usage, such as the structure, single use or combination, addition amount, etc. can be arbitrarily set according to the performance design of the final planographic printing plate precursor. For example, it is selected from the following viewpoints.
From the viewpoint of sensitivity, a structure having a large unsaturated group content per molecule is preferable, and in many cases, a bifunctional or higher functionality is preferable. Further, in order to increase the strength of the image portion, that is, the cured film, those having three or more functionalities are preferable, and furthermore, different functional numbers and different polymerizable groups (for example, acrylic acid ester, methacrylic acid ester, styrenic compound, vinyl ether). It is also effective to adjust both sensitivity and strength by using a compound of the type).
In addition, the selection and use method of the addition polymerization compound is also an important factor for the compatibility and dispersibility with other components in the image recording layer (for example, binder polymer, radical polymerization initiator, colorant, etc.). For example, the compatibility may be improved by using a low-purity compound or using two or more kinds in combination. In addition, a specific structure may be selected for the purpose of improving the adhesion of the support or the protective layer.

In the present invention, the polymerizable compound (C) is preferably used in the range of 5 to 80% by mass, and more preferably 25 to 75% by mass with respect to the nonvolatile component in the image recording layer.
In addition, the use method of the addition polymerizable compound can arbitrarily select an appropriate structure, blending, and addition amount from the viewpoint of polymerization inhibition with respect to oxygen, resolution, fogging, refractive index change, surface adhesiveness, etc. Depending on the case, a layer configuration / coating method such as undercoating or overcoating can be carried out.

  The image recording layer of the present invention can contain the following components as required.

<Binder polymer>
In the image recording layer of the present invention, a binder polymer can be used in order to improve the film strength of the image recording layer. As the binder polymer that can be used in the present invention, conventionally known binder polymers can be used without limitation, and polymers having film properties are preferred. Examples of such binder polymers include acrylic resins, polyvinyl acetal resins, polyurethane resins, polyurea resins, polyimide resins, polyamide resins, epoxy resins, polystyrene resins, novolac phenolic resins, polyester resins, synthetic rubbers, natural rubbers. Is mentioned.
Particularly preferred are acrylic resins, polyvinyl acetal resins, and polyurethane resins.
These binder polymers may have crosslinkability in order to improve the film strength of the image area. In order to impart crosslinkability to the binder polymer, a crosslinkable functional group such as an ethylenically unsaturated bond may be introduced into the main chain or side chain of the polymer. The crosslinkable functional group may be introduced by copolymerization.
Examples of the polymer having an ethylenically unsaturated bond in the main chain of the molecule include poly-1,4-butadiene and poly-1,4-isoprene.
Examples of polymers having an ethylenically unsaturated bond in the side chain of the molecule are polymers of esters or amides of acrylic acid or methacrylic acid, where the ester or amide residue (R of -COOR or CONHR) is ethylene. Examples thereof include polymers having a polymerizable unsaturated bond.

Examples of the residue (the R) having an ethylenically unsaturated _{bond, - (CH 2) n CR} 1 = CR 2 R 3, - (CH 2 O) n CH 2 CR 1 = CR 2 R 3, - _{(CH 2 CH 2 O) n} CH 2 CR 1 = CR 2 R 3, - (CH 2) n NH-CO-O-CH 2 CR 1 = CR 2 R 3, - (CH 2) n -O-CO —CR ¹ ═CR ² R ³ and (CH ₂ CH ₂ O) ₂ —X (wherein R ^{1 to} R ³ are each a hydrogen atom, a halogen atom, or an alkyl group having 1 to 20 carbon atoms, an aryl group, and alkoxy. R ¹ and R ² or R ³ may be bonded to each other to form a ring, n represents an integer of 1 to 10. X represents a dicyclopentadienyl residue. Represents a group).
Specific examples of the ester _{residue, -CH 2 CH = CH 2,} ( described in JP Kokoku _{7-21633.) - CH 2 CH 2} O-CH 2 CH = CH 2, -CH 2 C _{(CH 3) = CH 2,} -CH 2 CH = CH-C 6 H 5, -CH 2 CH 2 OCOCH = CH-C 6 H 5, -CH 2 CH 2 -NHCOO-CH 2 CH = CH 2 and CH ₂ CH ₂ O—X (wherein X represents a dicyclopentadienyl residue).
Specific examples of the amide residue include —CH ₂ CH═CH ₂ , —CH ₂ CH ₂ —Y (wherein Y represents a cyclohexene residue), —CH ₂ CH ₂ —OCO—CH═CH _2. Is mentioned.

  The binder polymer having crosslinkability, for example, has a free radical (polymerization initiation radical or a growth radical in the polymerization process of the polymerizable compound) added to the crosslinkable functional group, and the polymerization chain of the polymerizable compound is formed directly between the polymers. Through addition polymerization, a cross-link is formed between the polymer molecules and cured. Alternatively, atoms in the polymer (eg, hydrogen atoms on carbon atoms adjacent to the functional bridging group) are abstracted by free radicals to form polymer radicals that are bonded together, thereby causing cross-linking between polymer molecules. Forms and cures.

  The content of the crosslinkable group in the binder polymer (content of unsaturated double bond capable of radical polymerization by iodine titration) is preferably 0.1 to 10.0 mmol, more preferably 1.0, per 1 g of the binder polymer. -7.0 mmol, most preferably 2.0-5.5 mmol. Within this range, good sensitivity and good storage stability can be obtained.

  Moreover, it is preferable that the binder polymer used by this invention has a hydrophilic group. The hydrophilic group contributes to imparting on-press developability to the image recording layer. In particular, the coexistence of a crosslinkable group and a hydrophilic group makes it possible to achieve both printing durability and developability.

  Examples of the hydrophilic group include a hydroxy group, a carboxyl group, a carboxylate group, a hydroxyethyl group, an alkylene oxide structure, a hydroxypropyl group, a polyoxyethyl group, a polyoxypropyl group, an amino group, an aminoethyl group, and an aminopropyl group. , An ammonium group, an amide group, a carboxymethyl group, a sulfo group, a phosphoric acid group, and the like. Preferred examples include an amide group, a hydroxy group, a polyoxyethyl group, and an alkylene oxide structure. The following general formula (2) The alkylene oxide structure represented by is most preferable. It is preferable to have this alkylene oxide structure in the side chain.

  In formula (2), R represents a hydrogen atom or a methyl group, a is 1, 3 or 5, and n represents an integer of 1 to 9. n is preferably an integer of 1 to 8, more preferably an integer of 1 to 7, still more preferably an integer of 1 to 6, and most preferably an integer of 2 to 4.

In order to impart a hydrophilic group to the acrylic resin, a hydrophilic monomer may be copolymerized. Specific examples of the copolymerization monomer having a hydrophilic group include acrylamide, methacrylamide, N, N-dimethylacrylamide, N-isopropylacrylamide, N-vinylpyrrolidone, N-vinylacetamide, N-acryloylmorpholine, 2-hydroxyethyl. Acrylate, 2-hydroxyethyl methacrylate, polyoxyethylene monomethacrylate, polyoxyethylene monoacrylate, polyoxypropylene monomethacrylate, polyoxypropylene monoacrylate, (meth) acrylic acid ester of polyoxyethylene monoalkyl ether, polyoxypropylene mono Examples include (meth) acrylic acid esters of alkyl ethers.
These can be used alone or in combination of two or more. The content of these structural units having a hydrophilic group is preferably 1 to 85 mol%, particularly preferably 5 to 70, in the polymer. Mol%.

Furthermore, a lipophilic group having a carbon atom such as an alkyl group, an aryl group, an aralkyl group, or an alkenyl group can be introduced into the present invention to the extent that the effect is not impaired. The inking property can be controlled by these.
In order to impart lipophilicity to the acrylic resin, a lipophilic monomer may be copolymerized. The copolymerization monomer is selected from, for example, acrylic esters, methacrylic esters, N, N-2 substituted acrylamides, N, N-2 substituted methacrylamides, styrenes, acrylonitriles, methacrylonitriles, and the like. Monomer.

  Specifically, for example, acrylic esters such as alkyl acrylate (the alkyl group preferably has 1 to 20 carbon atoms) (specifically, for example, methyl acrylate, ethyl acrylate, acrylic Propyl butyl, butyl acrylate, amyl acrylate, ethyl hexyl acrylate, octyl acrylate, tert-octyl acrylate, chloroethyl acrylate, 2,2-dimethylhydroxypropyl acrylate, 5-hydroxypentyl acrylate, trimethylolpropane monoacrylate , Pentaerynuritol monoacrylate, glycidyl acrylate, benzyl acrylate, methoxybenzyl acrylate, furfuryl acrylate, tetrahydrofurfuryl acrylate, etc.), aryl acrylate (e.g., phenyl Methacrylic acid esters (eg, methyl methacrylate, ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, amyl methacrylate, hexyl methacrylate, cyclohexyl). Methacrylate, benzyl methacrylate, chlorobenzyl methacrylate, octyl methacrylate, 4-hydroxybutyl methacrylate, 5-hydroxypentyl methacrylate, 2,2-dimethyl-3-hydroxypropyl methacrylate, trimethylolpropane monomethacrylate, pentaerythritol monomethacrylate, Glycidyl methacrylate, furfuryl methacrylate, tetrahydrofurfuryl methacrylate Styrene) such as methyl methacrylate, dimethyl styrene, trimethyl styrene, ethyl styrene, diethyl styrene, isopropyl styrene, butyl, aryl methacrylate (for example, phenyl methacrylate, cresyl methacrylate, naphthyl methacrylate, etc.), styrene, alkyl styrene, etc. Styrene, hexyl styrene, cyclohexyl styrene, decyl styrene, benzyl styrene, chloromethyl styrene, trifluoromethyl styrene, ethoxymethyl styrene, acetoxymethyl styrene, etc.), alkoxy styrene (for example, methoxy styrene, 4-methoxy-3-methyl styrene, dimethoxy) Styrene), halogen styrene (e.g., chlorostyrene, dichlorostyrene, trichlorostyrene, tetrachlors) Styrene, pentachlorostyrene, prom styrene, dibromostyrene, iodostyrene, fluorostyrene, trifluorostyrene, 2-bromo-4-trifluoromethylstyrene, 4-fluoro-3-trifluoromethylstyrene, etc.), acrylonitrile, Examples include methacrylonitrile.

  Specific examples of the binder polymer used in the present invention are shown below, but the present invention is not limited thereto.

  In order to enhance the on-press developability of the image recording layer, it is also effective to use a lipophilic binder polymer and a hydrophilic binder polymer in combination. Specific examples of hydrophilic binder polymers include gum arabic, casein, gelatin, starch derivatives, carboxymethylcellulose and its sodium salt, cellulose acetate, sodium alginate, vinyl acetate-maleic acid copolymers, styrene-maleic acid copolymers, polyacrylic Acids and their salts, polymethacrylic acids and their salts, homopolymers and copolymers of hydroxyethyl methacrylate, homopolymers and copolymers of hydroxyethyl acrylate, homopolymers and copolymers of hydroxypropyl methacrylate, homopolymers and copolymers of hydroxypropyl acrylate , Hydroxybutyl methacrylate homopolymers and copolymers, hydroxybutyl acrylate homopolymers and Polymers, polyethylene glycols, hydroxypropylene polymers, polyvinyl alcohols, homopolymers of hydrolyzed polyvinyl acetate, polyvinyl formal, polyvinyl butyral, polyvinyl pyrrolidone, acrylamide having a hydrolysis degree of 60 mol% or more, preferably 80 mol% or more And copolymers, homopolymers and polymers of methacrylamide, homopolymers and copolymers of N-methylolacrylamide, polyvinylpyrrolidone, alcohol soluble nylon, poly of 2,2-bis- (4-hydroxyphenyl) -propane and epichlorohydrin Examples include ether.

  The binder polymer in the present invention preferably has a mass average molar mass (Mw) of 2,000 or more, more preferably 5,000 or more, more preferably 10,000 to 300,000, and a number average average. It is preferable that molar mass (Mn) is 1000 or more, and it is more preferable that it is 2000-250,000. The polydispersity (mass average molar mass / number average molar mass) is preferably 1.1 to 10.

  The binder polymer can be obtained by purchasing a commercial product or synthesizing it by a known method.

The content of the binder polymer is 5 to 90% by mass, preferably 5 to 80% by mass, and more preferably 10 to 70% by mass with respect to the total solid content of the image recording layer. Within this range, good image area strength and image formability can be obtained.
Moreover, it is preferable to use a polymeric compound and a binder polymer in the quantity used as 0.5 / 1-4/1 by mass ratio.

<Microcapsules and microgels>
The image recording layer in the invention preferably takes an embodiment containing microcapsules and / or microgels from the viewpoint of obtaining good on-press developability. That is, the image recording layer constituent components (A) to (C) and other constituent components described later are included in microcapsules or microgels.
The microcapsule used in the present invention is, for example, a component of the image recording layer (the components (A) to (C) described above) as described in JP-A Nos. 2001-277740 and 2001-277742. All or part of the microcapsules are encapsulated. The constituent components of the image recording layer can also be contained outside the microcapsules. Furthermore, the image recording layer containing microcapsules is preferably a mode in which hydrophobic constituent components are encapsulated in microcapsules and hydrophilic constituent components are contained outside the microcapsules.

  On the other hand, in the present invention, the image recording layer may be an embodiment containing crosslinked resin particles, that is, microgel. This microgel can contain a part of the above-mentioned (A) to (C) in and / or on the surface thereof. In particular, an embodiment in which a reactive microgel is formed by having (C) a polymerizable compound on the surface thereof is particularly preferable from the viewpoint of image forming sensitivity and printing durability.

  As a method for microencapsulating or microgelling the constituent components of the image recording layer, known methods can be applied.

  For example, as a method for producing a microcapsule, US Pat. No. 2,800,547, US Pat. No. 2,800,498, a method using coacervation, US Pat. No. 3,287,154, Japanese Patent Publication No. 38-19574, 42-446 by the interfacial polymerization method, U.S. Pat. Nos. 3,418,250 and 3,660,304, by precipitation of polymers, and U.S. Pat. No. 3,796,669. Urea-formaldehyde found in US Pat. No. 3,914,511, US Pat. No. 3,914,511, US Pat. No. 3,914,511, US Pat. No. 4,087,376 and US Pat. No. 4,089,802. System or urea formaldehyde-resorcino A method using a wall-based wall forming material, a method using a wall material such as melamine-formaldehyde resin and hydroxycellulose, as described in US Pat. No. 4,025,445, and Japanese Patent Publication Nos. 36-9163 and 51-9079. In situ method by monomer polymerization, spraying method found in British Patent No. 930422, US Pat. No. 3,111,407, electrolytic dispersion cooling method seen in British Patent Nos. 952807 and 967074 However, it is not limited to these.

  A preferable microcapsule wall used in the present invention has a three-dimensional cross-linking and has a property of swelling with a solvent. From such a viewpoint, the wall material of the microcapsule is preferably polyurea, polyurethane, polyester, polycarbonate, polyamide, and a mixture thereof, and particularly preferably polyurea and polyurethane. Moreover, you may introduce | transduce into the microcapsule wall the compound which has crosslinkable functional groups, such as an ethylenically unsaturated bond which can be introduce | transduced into the above-mentioned binder polymer.

On the other hand, as a method for preparing a microgel, granulation by interfacial polymerization described in JP-B-38-19574 and JP-A-42-446, as described in JP-A-5-61214 It is possible to use granulation by non-aqueous dispersion polymerization. However, it is not limited to these methods.
As the method using the interfacial polymerization, the above-described known microcapsule production method can be applied.

  Preferred microgels used in the present invention are those granulated by interfacial polymerization and having three-dimensional crosslinking. From such a viewpoint, the material to be used is preferably polyurea, polyurethane, polyester, polycarbonate, polyamide, and a mixture thereof, and polyurea and polyurethane are particularly preferable.

  The average particle size of the microcapsules or microgel is preferably 0.01 to 3.0 μm. 0.05-2.0 micrometers is further more preferable, and 0.10-1.0 micrometer is especially preferable. Within this range, good resolution and stability over time can be obtained.

<Other ingredients>
The image recording layer in the invention may further contain other components as required.
Hereinafter, other components constituting the image recording layer in the invention will be described.

(1) Surfactant A surfactant can be used in the image recording layer in the invention in order to improve the coated surface state.
Examples of the surfactant include nonionic surfactants, anionic surfactants, cationic surfactants, amphoteric surfactants, and fluorosurfactants. Among these, fluorosurfactants are preferable.

  Examples of the fluorosurfactant include a fluorosurfactant containing a perfluoroalkyl group in the molecule. Examples of such fluorosurfactants include anionic types such as perfluoroalkyl carboxylates, perfluoroalkyl sulfonates, and perfluoroalkyl phosphates; amphoteric types such as perfluoroalkyl betaines; Cation type such as trimethylammonium salt; perfluoroalkylamine oxide, perfluoroalkylethylene oxide adduct, oligomer containing perfluoroalkyl group and hydrophilic group, oligomer containing perfluoroalkyl group and lipophilic group, perfluoroalkyl Nonionic types such as an oligomer containing a group, a hydrophilic group and a lipophilic group, and a urethane containing a perfluoroalkyl group and a lipophilic group. Moreover, the fluorine-type surfactant described in each gazette of Unexamined-Japanese-Patent No. 62-170950, 62-226143, and 60-168144 is also mentioned suitably.

Surfactant can be used individually or in combination of 2 or more types.
The content of the surfactant is preferably 0.001 to 10% by mass and more preferably 0.01 to 5% by mass with respect to the total solid content of the image recording layer.

(2) Colorant In the image recording layer of the present invention, a dye having a large absorption in the visible light region can be used as an image colorant. Specifically, Oil Yellow # 101, Oil Yellow # 103, Oil Pink # 312, Oil Green BG, Oil Blue BOS, Oil Blue # 603, Oil Black BY, Oil Black BS, Oil Black T-505 (orientated chemistry) Kogyo Co., Ltd.) and the dyes described in JP-A-62-293247. Also, pigments such as phthalocyanine pigments, azo pigments, carbon black, titanium oxide, etc. can be suitably used.
When these colorants are used, it is easy to distinguish between an image area after image formation and a non-image area, so it is preferable to add them.
The amount added is 0.01 to 10% by mass with respect to the total solid content of the image recording layer.

(3) Print-out agent To the image-recording layer according to the invention, a compound that is discolored by an acid or a radical can be added to form a print-out image.
As such a compound, for example, various dyes such as diphenylmethane, triphenylmethane, thiazine, oxazine, xanthene, anthraquinone, iminoquinone, azo, and azomethine are effectively used.

  Specific examples include brilliant green, quinaldine red, rose bengal, metanil yellow, thymol sulfophthalein, xylenol blue, methyl orange, paramethyl red, congo red, benzopurpurin 4B, α-naphthyl red, Nile blue 2B. , Nile Blue A, Oil Blue # 603 [manufactured by Orient Chemical Industries, Ltd.], Oil Pink # 312 [manufactured by Orient Chemical Industries, Ltd.], Oil Red 5B [manufactured by Orient Chemical Industries, Ltd.], Oil Scarlet # 308 [Orient Chemical Industries, Ltd.], Oil Red OG [Orient Chemical Industries, Ltd.], Oil Red RR [Orient Chemical Industries, Ltd.], Oil Green # 502 [Orient Chemical Industries, Ltd.], Spiron Red BEH Special [Hodogaya Manufactured by Kogyo Co., Ltd.], m-cresol purple, cresol red, sulforhodamine B, 4-p-diethylaminophenyliminonaphthoquinone, 2-carboxyanilino-4-p-diethylaminophenyliminonaphthoquinone, 2-carboxystearylamino-4 -PN, N-bis (hydroxyethyl) amino-phenyliminonaphthoquinone, 1-phenyl-3-methyl-4-p-diethylaminophenylimino-5-pyrazolone, 1-β-naphthyl-4-p-diethylaminophenyl Examples thereof include dyes such as imino-5-pyrazolone, and leuco dyes such as p, p ′, p ″ -hexamethyltriaminotriphenylmethane (leuco crystal violet) and Pergascript Blue SRB (manufactured by Ciba Geigy).

  In addition to the above, a leuco dye known as a material for thermal paper or pressure-sensitive paper is also suitable. Specific examples include crystal violet lactone, malachite green lactone, benzoyl leucomethylene blue, 2- (N-phenyl-N-methylamino) -6- (Np-tolyl-N-ethyl) amino-fluorane, 2-anilino. -3-methyl-6- (N-ethyl-p-toluidino) fluorane, 3,6-dimethoxyfluorane, 3- (N, N-diethylamino) -5-methyl-7- (N, N-dibenzylamino) ) -Fluorane, 3- (N-cyclohexyl-N-methylamino) -6-methyl-7-anilinofluorane, 3- (N, N-diethylamino) -6-methyl-7-anilinofluorane, 3 -(N, N-diethylamino) -6-methyl-7-xylidinofluorane, 3- (N, N-diethylamino) -6-methyl-7-chloro Fluorane, 3- (N, N-diethylamino) -6-methoxy-7-aminofluorane, 3- (N, N-diethylamino) -7- (4-chloroanilino) fluorane, 3- (N, N-diethylamino) -7-chlorofluorane, 3- (N, N-diethylamino) -7-benzylaminofluorane, 3- (N, N-diethylamino) -7,8-benzofluorane, 3- (N, N-dibutyl) Amino) -6-methyl-7-anilinofluorane, 3- (N, N-dibutylamino) -6-methyl-7-xylidinofluorane, 3-piperidino-6-methyl-7-anilinofluorane 3-pyrrolidino-6-methyl-7-anilinofluorane, 3,3-bis (1-ethyl-2-methylindol-3-yl) phthalide, 3,3-bis (1-n-butyl- -Methylindol-3-yl) phthalide, 3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide, 3- (4-diethylamino-2-ethoxyphenyl) -3- (1-ethyl- 2-methylindol-3-yl) -4-zaphthalide, 3- (4-diethylaminophenyl) -3- (1-ethyl-2-methylindol-3-yl) phthalide, and the like.

  A suitable addition amount of the dye that changes color by an acid or a radical is preferably 0.01 to 10% by mass with respect to the solid content of the image recording layer.

(4) Polymerization inhibitor In the image recording layer of the present invention, a small amount of a thermal polymerization inhibitor is added in order to prevent unnecessary thermal polymerization of the polymerizable compound (C) during the production or storage of the image recording layer. It is preferable to add.
Examples of the thermal polymerization inhibitor include hydroquinone, p-methoxyphenol, di-t-butyl-p-cresol, pyrogallol, t-butylcatechol, benzoquinone, 4,4′-thiobis (3-methyl-6-t- (Butylphenol), 2,2′-methylenebis (4-methyl-6-tert-butylphenol), and N-nitroso-N-phenylhydroxylamine aluminum salt are preferred.
The addition amount of the thermal polymerization inhibitor is preferably about 0.01 to about 5% by mass with respect to the total solid content of the image recording layer.

(5) Higher fatty acid derivatives, etc. In order to prevent polymerization inhibition by oxygen, higher fatty acid derivatives such as behenic acid and behenic acid amide are added to the image recording layer in the present invention, and the drying process after coating is performed. May be unevenly distributed on the surface of the image recording layer.
The amount of the higher fatty acid derivative added is preferably about 0.1 to about 10% by mass with respect to the total solid content of the image recording layer.

(6) Plasticizer The image recording layer in the invention may contain a plasticizer in order to improve the on-press developability.
Examples of the plasticizer include phthalates such as dimethyl phthalate, diethyl phthalate, dibutyl phthalate, diisobutyl phthalate, dioctyl phthalate, octyl capryl phthalate, dicyclohexyl phthalate, ditridecyl phthalate, butyl benzyl phthalate, diisodecyl phthalate, diallyl phthalate; Glycol esters such as glycol phthalate, ethyl phthalyl ethyl glycolate, methyl phthalyl ethyl glycolate, butyl phthalyl butyl glycolate, triethylene glycol dicaprylate; Phosphate esters such as tricresyl phosphate and triphenyl phosphate Diisobutyl adipate, dioctyl adipate, dimethyl sebacate, dibutyl sebacate, dioct Ruazereto, aliphatic dibasic acid esters such as dibutyl maleate; polyglycidyl methacrylate, triethyl citrate, glycerin triacetyl ester, butyl laurate in.
The plasticizer content is preferably about 30% by mass or less based on the total solid content of the image recording layer.

(7) Inorganic fine particles The image recording layer in the present invention may contain inorganic fine particles in order to improve the cured film strength and the on-press developability.
Suitable inorganic fine particles include, for example, silica, alumina, magnesium oxide, titanium oxide, magnesium carbonate, calcium alginate, or a mixture thereof. These can be used for strengthening the film, enhancing interfacial adhesion by surface roughening, and the like.
The inorganic fine particles preferably have an average particle size of 5 nm to 10 μm, and more preferably 0.5 μm to 3 μm. Within the above range, it is possible to form a non-image portion having excellent hydrophilicity, which is stably dispersed in the image recording layer, sufficiently retains the film strength of the image recording layer, and hardly causes stains during printing.
The inorganic fine particles as described above can be easily obtained as a commercial product such as a colloidal silica dispersion.
The content of the inorganic fine particles is preferably 40% by mass or less, and more preferably 30% by mass or less, based on the total solid content of the image recording layer.

(8) Low molecular weight hydrophilic compound The image recording layer in the invention may contain a low molecular weight hydrophilic compound in order to improve the on-press developability without reducing the printing durability.
Examples of the low molecular weight hydrophilic compound include water-soluble organic compounds such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol and the like, and ether or ester derivatives thereof, glycerin, Polyhydroxys such as pentaerythritol and tris (2-hydroxyethyl) isocyanurate, organic amines such as triethanolamine and diethanolamine monoethanolamine and salts thereof, organic sulfones such as alkylsulfonic acid, toluenesulfonic acid and benzenesulfonic acid Acids and salts thereof, organic sulfamic acids such as alkylsulfamic acid and salts thereof, organic sulfates such as alkylsulfuric acid and alkylethersulfuric acid and salts thereof, Organic phosphonic acids and their salts such as Ruhosuhon acid, tartaric acid, oxalic acid, citric acid, malic acid, lactic acid, gluconic acid, organic carboxylic acids and salts thereof such as amino acids, betaines, and the like.

  Among these, in the present invention, it is preferable to contain at least one selected from the group consisting of polyols, alkyl sulfates, alkyl sulfonates, and betaines.

  Specific examples of organic sulfonates include sodium normal butyl sulfonate, sodium isobutyl sulfonate, sodium sec-butyl sulfonate, sodium tert-butyl sulfonate, sodium normal pentyl sulfonate, and sodium 1-ethylpropyl sulfonate. , Sodium normal hexyl sulfonate, sodium 1,2-dimethylpropyl sulfonate, sodium 2-ethylbutyl sulfonate, sodium 2-ethylhexyl sulfonate, sodium cyclohexyl sulfonate, sodium normal heptyl sulfonate, sodium normal octyl sulfonate, tert -Sodium octyl sulfonate, sodium normal nonyl sulfonate, sodium allyl sulfonate, 2-methylallyl sulfonic acid Thorium, sodium 4- [2- (2-butyloxy-ethoxy) -ethoxy] -butane-1-sulfonate, sodium 4- [2- (2-hexyloxy-ethoxy) -ethoxy] -butane-1-sulfonate 4- {2- [2- (2-ethyl) hexyloxy-ethoxy] -ethoxy} -butane-1-sulfonic acid sodium, 4- [2- (2-decyloxy-ethoxy) -ethoxy] -butane-1 Sodium sulfonate, 4- {2- [2- (2-butyloxy-ethoxy) -ethoxy] -ethoxy} -butane-1-sulfonic acid sodium, 4- [2- {2- [2- (2-ethyl) ) Hexyloxy-ethoxy] -ethoxy} -ethoxy] -butane-1-sulfonate, sodium benzenesulfonate, sodium p-toluenesulfonate , Sodium p-hydroxybenzenesulfonate, sodium p-styrenesulfonate, sodium dimethyl-5-sulfonate isophthalate, disodium 1,3-benzenedisulfonate, trisodium 1,3,5-benzenetrisulfonate, Sodium p-chlorobenzenesulfonate, sodium 3,4-dichlorobenzenesulfonate, sodium 1-naphthylsulfonate, sodium 2-naphthylsulfonate, sodium 4-hydroxynaphthylsulfonate, disodium 1,5-naphthalenedisulfonate, 2 , 6-Naphthalenedisulfonic acid disodium, 1,3,6-naphthalene trisulfonic acid trisodium, and lithium salt exchangers thereof.

  Specific examples of the organic sulfamate include sodium normal butyl sulfamate, sodium isobutyl sulfamate, sodium tert-butyl sulfamate, sodium normal pentyl sulfamate, sodium 1-ethylpropyl sulfamate, sodium normal hexyl sulfamate, Examples include sodium 1,2-dimethylpropylsulfamate, sodium 2-ethylbutylsulfamate, sodium cyclohexylsulfamate, and lithium salt exchangers thereof.

  These compounds have a small hydrophobic part structure and almost no surface-active action, and are clearly distinguished from the above-mentioned surfactants in which long-chain alkyl sulfonates and long-chain alkyl benzene sulfonates are used favorably. .

  As the organic sulfate, a compound represented by the following general formula (iii) is particularly preferably used.

  In the general formula (iii), R represents an alkyl group, an alkenyl group, an alkynyl group, an aryl group, or a heterocyclic group, m represents an integer of 1 to 4, and X represents sodium, potassium, or lithium. .

  R is preferably a linear, branched or cyclic alkyl group having 1 to 12 carbon atoms, an alkenyl group having 1 to 12 carbon atoms, an alkynyl group having 1 to 12 carbon atoms, or an aryl group having 20 or less carbon atoms. Can be mentioned. These groups may further have a substituent. In that case, examples of the substituent that can be introduced include linear, branched or cyclic alkyl groups having 1 to 12 carbon atoms, and those having 1 to 12 carbon atoms. Examples include an alkenyl group, an alkynyl group having 1 to 12 carbon atoms, a halogen atom, and an aryl group having 20 or less carbon atoms.

  Preferred examples of the compound represented by the general formula (iii) include sodium oxyethylene-2-ethylhexyl ether sulfate, sodium dioxyethylene-2-ethylhexyl ether sulfate, potassium dioxyethylene-2-ethylhexyl ether sulfate, dioxy Ethylene-2-ethylhexyl ether lithium sulfate, sodium trioxyethylene-2-ethylhexyl ether sulfate, sodium tetraoxyethylene-2-ethylhexyl ether sulfate, sodium dioxyethylene hexyl ether sulfate, sodium dioxyethylene octyl ether sulfate, dioxyethylene Examples include sodium lauryl ether sulfate. Of these, the most preferred compounds include sodium dioxyethylene-2-ethylhexyl ether sulfate, potassium dioxyethylene-2-ethylhexyl ether sulfate, and lithium dioxyethylene-2-ethylhexyl ether sulfate.

  As the betaines, compounds represented by the general formula (iv) and the general formula (v) are preferably used.

R ^{1 to} R ³ each independently represent an alkyl group having 1 to 5 carbon atoms, an alkenyl group, an alkynyl group, a cycloalkyl group or an aryl group, and may be substituted with a hydroxy group or an amino group. Z represents an alkylene group having 1 to 4 carbon atoms, and may be substituted with a hydroxy group. At least two of R ^{1 to} R ³ and Z may be bonded to form a heterocyclic ring. Among them, it is desirable R ¹ to R ³ is a heterocyclic 5-6 membered ring two are bonded alkyl group having 1 to 3 carbon atoms, or R ¹ to R ³ and Z,, in particular, R ¹ ~ quaternary ammonium skeleton R ³ is a methyl or ethyl group, or R ¹ to R ³ and two of pyrrolidine skeleton bonded to form a ring of Z,, piperidine skeleton, a pyridine skeleton, those having a imidazoline skeleton desirable.

  These compounds have a small hydrophobic part structure and almost no surface-active action, so that dampening water penetrates into the exposed part of the image recording layer (image part) and reduces the hydrophobicity and film strength of the image part. The ink receptivity and printing durability of the image recording layer can be maintained well.

The amount of these low molecular weight hydrophilic compounds added to the image recording layer is preferably 0.5% by mass or more and 20% by mass or less of the total solid content of the image recording layer. More preferably, they are 1 mass% or more and 10 mass% or less, More preferably, they are 2 mass% or more and 8 mass% or less. In this range, good on-press developability and printing durability can be obtained.
These compounds may be used alone or in combination of two or more.

(9) Grease-sensitizing agent In the case where an inorganic layered compound is contained in the protective layer described later, the phosphonium compound, nitrogen-containing low molecular weight compound, ammonium group-containing polymer, etc. A sensitizer can be used. Further, different types of sensitizers may be used in combination.
These compounds function as a surface coating agent (greasy sensitizer) for the inorganic layered compound, and prevent a decrease in the inking property during printing by the inorganic layered compound.

  Suitable phosphonium compounds include compounds represented by the following general formula (K1) described in JP-A-2006-297907 or the following general formula (K2) described in JP-A-2007-50660.

In Formula (K1), R ₁ ~R ₄ are each independently represents an alkyl group, an alkenyl group, an alkynyl group, a cycloalkyl group, an alkoxy group, an aryl group, an aryloxy group, an alkylthio Represents a group, a heterocyclic group or a hydrogen atom. At least two of R _{1 to} R ₄ may be bonded to form a ring. X ⁻ represents a counter anion.

In General Formula (K2), Ar _{1 to} Ar ₆ each independently represents an aryl group or a heterocyclic group, L represents a divalent linking group, X ⁿ⁻ represents an n-valent counter anion, and n Represents an integer of 1 to 3, and m represents a number satisfying nxm = 2. Here, as the aryl group, phenyl group, naphthyl group, tolyl group, xylyl group, fluorophenyl group, chlorophenyl group, bromophenyl group, methoxyphenyl group, ethoxyphenyl group, dimethoxyphenyl group, methoxycarbonylphenyl group, dimethylaminophenyl A group and the like are preferable. Examples of the heterocyclic group include a pyridyl group, a quinolyl group, a pyrimidinyl group, a thienyl group, and a furyl group. L represents a divalent linking group. 6-15 are preferable and, as for carbon number in a coupling group, More preferably, it is a C6-C12 coupling group. Preferred examples of X ⁿ⁻ include halide ions such as Br ⁻ and I ⁻ , toluenesulfonate, naphthalene-1,7-disulfonate, naphthalene-1,3,6-trisulfonate, and 5-benzoyl-4- Examples include sulfonate anions such as hydroxy-2-methoxybenzene-4-sulfonate, carboxylate anions, sulfate anions, sulfate anions, PF ₆ ⁻ , BF ₄ ⁻ , and perchlorate anions. Of these, a sulfonate anion is particularly preferable.

  Specific examples of the phosphonium compound represented by the general formula (K1) or (K2) are shown below.

  In addition to the above-mentioned phosphonium compound, the following nitrogen-containing low molecular weight compounds can be mentioned as the sensitizers preferably used in the present invention. Preferred nitrogen-containing low molecular weight compounds include compounds having the structure of the following general formula (K3).

In the formula, R ^{1 to} R ⁴ each independently represents a substituted or unsubstituted alkyl group, alkenyl group, alkynyl group, cycloalkyl group, alkoxy group, aryl group, aralkyl group, heterocyclic group or hydrogen atom. At least two of R ^{1 to} R ⁴ may be bonded to form a ring. X ⁻ is an anion, PF ₆ ⁻ , BF ₄ ⁻ , or an organic sulfone having a substituent selected from an alkyl group, an alkenyl group, an alkynyl group, a cycloalkyl group, an alkoxy group, an aryl group, an aralkyl group, and a heterocyclic group Indicates an acid anion.

That the nitrogen-containing low molecular weight compound for use in the present invention include quaternary ammonium salts wherein at least one amine salt is a hydrogen atom R ¹ to R ^4, and R ¹ to R ⁴ is not any hydrogen atom . In addition, imidazolinium salts represented by the following general formula (K4), benzimidazolinium salts represented by the following general formula (K5), pyridinium salts represented by the following general formula (K6), and the following general formula (K7) The quinolinium salt structure may be used.

In the above formula, R ⁵ and R ^{6 each} represents a substituted or unsubstituted alkyl group, alkenyl group, alkynyl group, cycloalkyl group, alkoxy group, aryl group, aralkyl group, heterocyclic group or hydrogen atom. X < ^- > is an anion and is synonymous with X < ^- > of the said general formula (K3).

  Among these, quaternary ammonium salts and pyridinium salts are preferably used. Specific examples thereof are shown below.

  The amount of the phosphonium compound or nitrogen-containing low molecular weight compound added to the image recording layer is preferably 0.01 to 20% by mass, more preferably 0.05 to 10% by mass, based on the solid content of the image recording layer. 5% by mass is most preferred. Within these ranges, good ink fillability during printing can be obtained.

  As the sensitizer used in the present invention, the following ammonium group-containing polymers are also preferred. The ammonium group-containing polymer may be any polymer as long as it has an ammonium group in its structure, but is preferably a polymer containing structures of the following general formulas (K8) and (K9) as repeating units.

(Wherein R ¹¹ and R ¹² each independently represent a hydrogen atom or a methyl group. R ² represents an alkylene group which may have a substituent, an alkyleneoxy group which may have a substituent, etc. R ³¹ , R ³² and R ³³ each independently represents an alkyl group having 1 to 10 carbon atoms or an aralkyl group, and X ⁻ has Br ⁻ , I ⁻ and a substituent. Benzene sulfonate anion, methyl sulfate anion, ethyl sulfate anion, propyl sulfate anion, butyl sulfate anion which may be branched, amyl sulfate anion which may be branched, PF ₆ ⁻ , BF ₄ ⁻ , B (C ₆ F ₅ ) ₄ represents an organic or inorganic anion such as ₄ ⁻ , where R ⁴ is an alkyl group having 1 to 21 carbon atoms, an aralkyl group, an aryl group, — (C ₂ H ₄ O) _n —R ⁵ , or — (C ₃ H ₆ O) represents an _n -R ^5, R ⁵ .n represents a hydrogen atom, a methyl group or an ethyl group is 1 or 2.)

  The ammonium salt-containing polymer contains at least one structural unit represented by general formula (K8) and general formula (K9), but either one may be two or more, and both are 2 There may be more than species. Although the ratio of both structural units is not limited, The molar ratio is particularly preferably 5:95 to 80:20. Moreover, this polymer may contain another copolymerization component within the range which can ensure the effect of this invention.

  The ammonium salt-containing polymer has a reduced specific viscosity (unit: cSt / g / ml) determined by the following measurement method, preferably in the range of 5 to 120, more preferably in the range of 10 to 110. The range of 15-100 is especially preferable.

<Measurement method of reduced specific viscosity>
Weigh 3.33 g of 30% polymer solution (1 g as solid content) into a 20 ml volumetric flask and make up with N-methylpyrrolidone. This solution is put into an Ubbelohde reduced viscosity tube (viscosity constant = 0.010 cSt / s), and the time for flowing at 30 ° C. is measured. Time to pass (second) ") is calculated by the usual method.

The content of the ammonium salt-containing polymer is preferably 0.0005% by mass to 30.0% by mass, more preferably 0.001% by mass to 20.0% by mass with respect to the total solid content of the image recording layer. 002% by mass to 15.0% by mass is most preferable. Within this range, good inking properties can be obtained. The ammonium salt-containing polymer may be further contained in the protective layer.
Specific examples of the ammonium salt-containing polymer are shown below.

<Formation of image recording layer>
The image recording layer in the present invention is formed by preparing or applying a coating solution by dispersing or dissolving the necessary components described above in a solvent, and coating and drying the coating solution.
Solvents used here include ethylene dichloride, cyclohexanone, methyl ethyl ketone, methanol, ethanol, propanol, ethylene glycol monomethyl ether, 1-methoxy-2-propanol, 2-methoxyethyl acetate, 1-methoxy-2-propyl acetate, dimethoxy Examples include ethane, methyl lactate, ethyl lactate, N, N-dimethylacetamide, N, N-dimethylformamide, tetramethylurea, N-methylpyrrolidone, dimethyl sulfoxide, sulfolane, γ-butyllactone, toluene, water, and the like. However, the present invention is not limited to this. These solvents are used alone or in combination. The solid content concentration of the coating solution is preferably 1 to 50% by mass.

  In the image recording layer of the present invention, a plurality of coating solutions in which the same or different components are dispersed or dissolved in the same or different solvents are prepared, and coating and drying are repeated a plurality of times to form a multilayered image recording layer. It is also possible.

Further, coating amount of the image-recording layer on the support after drying (solid content) may be varied according to the intended purpose, generally 0.3 to 3.0 g / m ² is preferred. Within this range, good sensitivity and good film properties of the image recording layer can be obtained.
Various methods can be used as the coating method. Examples thereof include bar coater coating, spin coating, spray coating, curtain coating, dip coating, air knife coating, blade coating, and roll coating.

(Undercoat layer)
In the lithographic printing plate precursor according to the invention, an undercoat layer (sometimes referred to as an intermediate layer) is preferably provided between the image recording layer and the support. The undercoat layer enhances the adhesion between the support and the image recording layer in the exposed area, and easily peels off the image recording layer from the support in the unexposed area. Contributes to improvement. In addition, in the case of infrared laser exposure, since the undercoat layer functions as a heat insulating layer, the heat generated by exposure does not diffuse to the support and can be used efficiently, so that the sensitivity can be increased. is there. Below, the component etc. which are used for the undercoat of this invention are demonstrated.

Specific examples of the undercoat layer compound include a silane coupling agent having an addition polymerizable ethylenic double bond reactive group described in JP-A-10-282679, and JP-A-2-304441. The phosphorus compound etc. which have the ethylenic double bond reactive group of gazette publication are mentioned suitably.
As the most preferable undercoat layer compound, a polymer resin having an adsorptive group, a hydrophilic group, and a crosslinkable group can be mentioned. This polymer resin is preferably formed by copolymerization of a monomer having an adsorptive group, a monomer having a hydrophilic group, and a monomer having a crosslinkable group.

The polymer resin for the undercoat layer preferably has an adsorptive group on the surface of the hydrophilic support. The presence or absence of adsorptivity to the surface of the hydrophilic support can be determined, for example, by the following method.
A coating night is prepared by dissolving the test compound in a readily soluble solvent, and the coating night is coated and dried on the support so that the coating amount after drying is 30 mg / m ² . Next, after the support coated with the test compound is sufficiently washed with an easily soluble solvent, the residual amount of the test compound that has not been removed by washing is measured to calculate the support adsorption amount. Here, the measurement of the remaining amount may be performed by directly quantifying the amount of the remaining compound or by quantifying the amount of the test compound dissolved in the cleaning liquid. The compound can be quantified by, for example, fluorescent X-ray measurement, reflection spectral absorbance measurement, liquid chromatography measurement and the like. A compound having a support adsorptivity is a compound that remains at 1 mg / m ² or more even after the washing treatment as described above.

The adsorptive group on the surface of the hydrophilic support is a substance (for example, metal, metal oxide) present on the surface of the hydrophilic support, or a functional group (for example, a hydroxy group) and a chemical bond (for example, an ionic bond, It is a functional group capable of causing a hydrogen bond, a coordinate bond, and a bond due to intermolecular force. The adsorptive group is preferably an acid group or a cationic group.
The acid group preferably has an acid dissociation constant (pKa) of 7 or less. Examples of the acid group include a phenolic hydroxy group, a carboxy group, —SO ₃ H, —OSO ₃ H, —PO ₃ H ₂ , —OPO ₃ H ₂ , —CONHSO ₂ —, —SO ₂ NHSO ₂ , —COCH _2. COCH ₃ may be mentioned. Of these, —OPO ₃ H ₂ and PO ₃ H ₂ are particularly preferable. These acid groups may be metal salts.
The cationic group is preferably an onium group. Examples of the onium group include an ammonium group, a phosphonium group, an arsonium group, a stibonium group, an oxonium group, a sulfonium group, a selenonium group, a stannonium group, and an iodonium group. Among these, an ammonium group, a phosphonium group, and a sulfonium group are preferable, an ammonium group and a phosphonium group are more preferable, and an ammonium group is most preferable.

  As a particularly preferred example of the monomer having an adsorptive group used when synthesizing a polymer resin suitable as a compound for the undercoat layer, a compound represented by the following general formula (U1) or general formula (U2) can be given. It is done.

In the general formulas (U1) and (U2), R ¹ , R ² , and R ³ are each independently a hydrogen atom, a halogen atom, or an alkyl group having 1 to 6 carbon atoms.
R ¹ , R ² and R ³ are each independently preferably a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, preferably a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. More preferably, it is most preferably a hydrogen atom or a methyl group. R ² and R ³ are particularly preferably a hydrogen atom.
Z is a functional group that adsorbs to the surface of the hydrophilic support, and the adsorptive functional group is as described above.

In the general formulas (U1) and (U2), L is a single bond or a divalent linking group.
L is a divalent aliphatic group (alkylene group, substituted alkylene group, alkenylene group, substituted alkenylene group, alkynylene group, substituted alkynylene group), divalent aromatic group (arylene group, substituted arylene group), or divalent Or an oxygen atom (—O—), a sulfur atom (—S—), an imino (—NH—), a substituted imino (—NR—, R is an aliphatic group, an aromatic group Group or heterocyclic group) or a combination with carbonyl (—CO—).

The divalent aliphatic group may have a cyclic structure or a branched structure. The number of carbon atoms in the divalent aliphatic group is preferably 1 to 20, more preferably 1 to 15, and most preferably 1 to 10. The divalent aliphatic group is preferably a saturated aliphatic group rather than an unsaturated aliphatic group. Furthermore, the divalent aliphatic group may have a substituent, and examples of the substituent include a halogen atom, a hydroxy group, an aromatic group, and a heterocyclic group.
The number of carbon atoms of the divalent aromatic group is preferably 6 to 20, more preferably 6 to 15, and most preferably 6 to 10. In addition, the divalent aromatic group may have a substituent, and examples of the substituent include a halogen atom, a hydroxy group, an aliphatic group, an aromatic group, and a heterocyclic group.
The divalent heterocyclic group preferably has a 5-membered or 6-membered ring as a heterocycle. In addition, another heterocyclic ring, an aliphatic ring or an aromatic ring may be condensed with the heterocyclic ring. The divalent heterocyclic group may have a substituent, and examples of the substituent include a halogen atom, a hydroxy group, an oxo group (═O), a thioxo group (═S), an imino group (═NH ), A substituted imino group (= N—R, R is an aliphatic group, an aromatic group or a heterocyclic group), an aliphatic group, an aromatic group, or a heterocyclic group.

In the present invention, L is preferably a divalent linking group containing a plurality of polyoxyalkylene structures. The polyoxyalkylene structure is more preferably a polyoxyethylene structure. In other words, L preferably contains — (OCH ₂ CH ₂ ) _n — (n is an integer of 2 or more).
In General Formula (U1), X is an oxygen atom (—O—) or imino (—NH—). X is more preferably an oxygen atom.
In general formula (U2), Y is a carbon atom or a nitrogen atom. When Y is a nitrogen atom and L is linked to Y to form a quaternary pyridinium group, Z itself is adsorbable, so Z is not essential and Z may be a hydrogen atom.

  Examples of typical compounds represented by general formula (U1) or general formula (U2) are shown below.

  The polymer resin suitable as the compound for the undercoat layer preferably has a hydrophilic group. Examples of the hydrophilic group include a hydroxy group, a carboxy group, a carboxylate group, a hydroxyethyl group, a polyoxyethyl group, and a hydroxypropyl group. Preferred examples include a group, a polyoxypropyl group, an amino group, an aminoethyl group, an aminopropyl group, an ammonium group, an amide group, a carboxymethyl group, a sulfo group, and a phosphoric acid group. Of these, a sulfo group exhibiting high hydrophilicity is preferable.

Specific examples of the monomer having a sulfo group include methallyloxybenzenesulfonic acid, allyloxybenzenesulfonic acid, allylsulfonic acid, vinylsulfonic acid, p-styrenesulfonic acid, methallylsulfonic acid, acrylamide t-butylsulfonic acid, Examples include 2-acrylamido-2-methylpropanesulfonic acid, sodium salt of (3-acryloyloxypropyl) butylsulfonic acid, and amine salt. Among them, 2-acrylamido-2-methylpropanesulfonic acid sodium salt is preferable from the viewpoint of hydrophilic performance and handling of synthesis.
These are suitably used when synthesizing a polymer resin suitable as a compound for the undercoat layer.

  The polymer resin for the undercoat layer in the present invention preferably has a crosslinkable group. The crosslinkable group can improve the adhesion with the image area. In order to make the polymer resin for the undercoat layer crosslinkable, a crosslinkable functional group such as an ethylenically unsaturated bond is introduced into the side chain of the polymer, or the polar substituent of the polymer resin is countercharged. Or a compound having an ethylenically unsaturated bond may be introduced by forming a salt structure.

  An example of a polymer having an ethylenically unsaturated bond in the side chain of the molecule is an ester or amide polymer of acrylic acid or methacrylic acid, wherein the ester or amide residue (-COOR or CONHR R) is ethylene. The polymer which has an ionic unsaturated bond can be mentioned.

Examples of the residue (the R) having an ethylenically unsaturated _{bond, - (CH 2) n CR} 1 = CR 2 R 3, - (CH 2 O) n CH 2 CR 1 = CR 2 R 3, - _{(CH 2 CH 2 O) n} CH 2 CR 1 = CR 2 R 3, - (CH 2) n NH-CO-O-CH 2 CR 1 = CR 2 R 3, - (CH 2) n -O-CO —CR ¹ ═CR ² R ³ and (CH ₂ CH ₂ O) ₂ —X (wherein R ^{1 to} R ³ are each a hydrogen atom, a halogen atom or an alkyl group having 1 to 20 carbon atoms, an aryl group, Represents an alkoxy group or an aryloxy group, and R ¹ and R ² or R ³ may combine with each other to form a ring, n represents an integer of 1 to 10. X represents dicyclopentadienyl. Represents a residue).
Specific examples of the ester _{residue, -CH 2 CH = CH 2,} ( described in JP Kokoku _{7-21633.) - CH 2 CH 2} O-CH 2 CH = CH 2, -CH 2 C _{(CH 3) = CH 2,} -CH 2 CH = CH-C 6 H 5, -CH 2 CH 2 OCOCH = CH-C 6 H 5, -CH 2 CH 2 NHCOO-CH 2 CH = CH 2, and CH ₂ CH ₂ O—X (wherein X represents a dicyclopentadienyl residue).
Specific examples of the amide residue include —CH ₂ CH═CH ₂ , —CH ₂ CH ₂ O—Y (wherein Y represents a cyclohexene residue), —CH ₂ CH ₂ OCO—CH═CH _2. Is mentioned.
As the monomer having a crosslinkable group of the polymer resin for the undercoat layer, an ester or amide of acrylic acid or methacrylic acid having the crosslinkable group is preferable.

  The content of the crosslinkable group in the polymer resin for the undercoat layer (content of unsaturated double bond capable of radical polymerization by iodine titration) is preferably 0.1 to 10.0 mmol per 1 g of the polymer resin. Preferably it is 1.0-7.0 mmol, Most preferably, it is 2.0-5.5 mmol. Within this range, both good sensitivity and dirtiness and good storage stability can be obtained.

The polymer resin for the undercoat layer preferably has a mass average molar mass of 5000 or more, more preferably 10,000 to 300,000, and a number average molar mass of 1000 or more is preferable. More preferably, it is ˜250,000. The polydispersity (mass average molar mass / number average molar mass) is preferably 1.1 to 10.
The polymer resin for the undercoat layer may be any of a random polymer, a block polymer, a graft polymer, and the like, but is preferably a random polymer.

  The polymer resin for undercoating may be used alone or in combination of two or more.

  The undercoat layer of the present invention can contain a secondary or tertiary amine or a polymerization inhibitor in order to prevent stains during aging. Secondary or tertiary amines include imidazole, 4-dimethylaminopyridine, 4-dimethylaminobenzaldehyde, tris (2-hydroxy-1-methyl) amine, 1,4-diazabicyclo [2,2,2] octane ( DABCO), 1,5,7-triazabicyclo [4,4,0] dec-5-ene, 1,8-diazabicyclo [5,4,0] undec-7-ene, 1,10-phenanthroline, 1 , 8-bis (dimethylamino) naphthalene, 4,4′-bis (dimethylamino) biphenyl, diphenylamine, 1,3-diphenylguanidine, 4-phenylpyridine, N, N′-ethylenebis (2,2,5,5) 5-tetramethylpyrrolidine) and the like.

  Examples of the polymerization inhibitor include known thermal polymerization inhibitors. Among them, preferred polymerization inhibitors are phenolic hydroxy group-containing compounds, quinone compounds, N-oxide compounds, piperidine-1-oxyl free radical compounds, pyrrolidine-1-oxyl free radical compounds, N-nitrosophenyl hydroxyl. And amines, diazonium compounds, cationic dyes, sulfide group-containing compounds, and nitro group-containing compounds. Of the above compounds, quinone compounds are particularly preferred. Specific examples of the quinone compounds include 1,4-benzoquinone, 2,3,5,6-tetrahydroxy-1,4-benzoquinone 2,5-dihydroxy-1,4-benzoquinone, chloranil, and 2,3-dichloro. -5,6-dicyano-1,4-benzoquinone, naphthoquinone, 2-fluoro-1,4-naphthoquinone, 2-hydroxyethyl-1,4-naphthoquinone, anthraquinone, 1,2,4-trihydroxyanthraquinone, 2, And 6-dihydroxyanthraquinone.

  The amount of these compounds added to the undercoat layer is preferably from 10 to 90% by mass, more preferably from 20 to 80% by mass, and most preferably from 30 to 70% by mass, based on the components of the undercoat layer.

Further, as the compound effective for preventing the contamination, a compound having an amino group or a functional group having a polymerization inhibiting ability and a group interacting with the surface of the aluminum support can also be used. Examples of the group that interacts with the surface of the aluminum support include trialkoxysilyl group, onium group, phenolic hydroxy group, carboxy group, —SO ₃ H, —OSO ₃ H, —PO ₃ H ₂ , —OPO ₃ H _2. , —CONHSO ₂ —, —SO ₂ NHSO ₂ — and COCH ₂ CO—, an acid group or a metal salt thereof.

  Examples of the compound having an interaction group between the amino group and the aluminum support surface include a salt of 1,4-diazabicyclo [2,2,2] octane and an acid, 4-aza-1-azoniabicyclo [2,2 , 2] Compound having at least one octane structure (for example, 1-methyl-4-aza-1-azoniabicyclo [2,2,2] octane = p-toluenesulfonate), ethylenediaminetetraacetic acid, hydroxyethylethylenediaminetriacetic acid , Dihydroxyethylethylenediaminediacetic acid, 1,3-propanediaminetetraacetic acid, diethylenetriaminepentaacetic acid, triethylenetetraminehexaacetic acid, hydroxyethyliminodiacetic acid, and the like. As a compound having a functional group having a polymerization inhibiting ability and a group that interacts with the surface of the aluminum support, 2-trimethoxysilylpropylthio-1,4-benzoquinone, 2,5-bis (trimethoxysilylpropylthio)- Examples include 1,4-benzoquinone, 2-carboxyanthraquinone, 2-trimethylammonioanthraquinone = bromide.

The undercoat layer coating solution is obtained by dissolving the above-described undercoat polymer resin and necessary additives in an organic solvent (for example, methanol, ethanol, acetone, methyl ethyl ketone, etc.) and / or water. The undercoat layer coating solution may contain an infrared absorber.
Various known methods can be used as a method of applying the undercoat layer coating solution to the support. Examples thereof include bar coater coating, spin coating, spray coating, curtain coating, dip coating, air knife coating, blade coating, and roll coating.
The coating amount (solid content) of the undercoat layer is preferably from 0.1-100 mg / m ^2, and more preferably 1 to 30 mg / m ^2.

(Support)
The support used in the lithographic printing plate precursor according to the invention is preferably an aluminum plate.
The aluminum plate is a pure aluminum plate, an alloy plate containing aluminum as a main component and containing a trace amount of different elements, or a plastic laminated on a thin film of aluminum or an aluminum alloy. Examples of foreign elements contained in the aluminum alloy include silicon, iron, manganese, copper, magnesium, chromium, zinc, bismuth, nickel, and titanium. The content of foreign elements in the alloy is preferably 10% by mass or less. In the present invention, a pure aluminum plate is preferable, but completely pure aluminum is difficult to manufacture in terms of refining technology, and therefore may contain a slightly different element. The composition of the aluminum plate is not specified, and a publicly known material can be used as appropriate.

  The thickness of the support is preferably from 0.1 to 0.6 mm, more preferably from 0.15 to 0.4 mm.

  Prior to using the aluminum plate, it is preferable to perform surface treatment such as roughening treatment or anodizing treatment. By the surface treatment, it is easy to improve hydrophilicity and secure adhesion between the image recording layer and the support. Prior to the roughening treatment of the aluminum plate, a degreasing treatment with a surfactant, an organic solvent, an alkaline aqueous solution or the like for removing rolling oil on the surface is performed as desired.

The surface roughening treatment of the aluminum plate is performed by various methods. For example, mechanical surface roughening treatment, electrochemical surface roughening treatment (electrochemical surface roughening treatment that dissolves the surface), chemical treatment, etc. Surface roughening treatment (roughening treatment that chemically selectively dissolves the surface).
As a method for the mechanical surface roughening treatment, a known method such as a ball polishing method, a brush polishing method, a blast polishing method, or a buff polishing method can be used. Moreover, the transcription | transfer method which transfers an uneven | corrugated shape with the roll which provided the unevenness | corrugation in the rolling stage of aluminum can also be used.
Examples of the electrochemical surface roughening treatment include a method in which an alternating current or a direct current is used in an electrolytic solution containing an acid such as hydrochloric acid or nitric acid. Another example is a method using a mixed acid as described in JP-A-54-63902.

  The surface-roughened aluminum plate is subjected to an alkali etching treatment using an aqueous solution of potassium hydroxide, sodium hydroxide or the like, if necessary, and further neutralized, and if desired, wear resistant. In order to increase the anodic oxidation treatment.

As the electrolyte used for the anodizing treatment of the aluminum plate, various electrolytes that form a porous oxide film can be used. In general, sulfuric acid, hydrochloric acid, oxalic acid, chromic acid or a mixed acid thereof is used. The concentration of these electrolytes is appropriately determined depending on the type of electrolyte.
The conditions of anodizing treatment vary depending on the electrolyte used, and thus cannot be specified in general. In general, however, an electrolyte concentration of 1 to 80% by mass solution, a liquid temperature of 5 to 70 ° C., a current density of 5 to 60 A / dm ² , voltage 1 to 100 V, and electrolysis time 10 seconds to 5 minutes are preferable. The amount of the anodized film formed is preferably from 1.0 to 5.0 g / m ^2, and more preferably 1.5 to 4.0 g / m ^2. Within this range, good printing durability and good scratch resistance of the non-image area of the lithographic printing plate can be obtained.

  As the support used in the present invention, the substrate having the above-mentioned surface treatment and having an anodized film may be used as it is. However, in order to further improve the adhesiveness with the upper layer, hydrophilicity, dirt resistance, heat insulation and the like. If necessary, it is immersed in an aqueous solution containing a hydrophilic compound and a micropore enlargement treatment or sealing treatment of an anodized film described in JP-A-2001-253181 or JP-A-2001-322365. The surface hydrophilization treatment to be performed can be appropriately selected and performed. Of course, the enlargement process and the sealing process are not limited to those described above, and any conventionally known methods can be performed. For example, as the sealing treatment, in addition to the vapor sealing, a single treatment with fluorinated zirconic acid, a treatment with sodium fluoride, and a vapor sealing with addition of lithium chloride are possible.

  The sealing treatment used in the present invention is not particularly limited, and a conventionally known method can be used. Among them, sealing treatment with an aqueous solution containing an inorganic fluorine compound, sealing treatment with water vapor, and hot water. Sealing treatment is preferred. Each will be described below.

<1> Sealing treatment with an aqueous solution containing an inorganic fluorine compound As the inorganic fluorine compound used for the sealing treatment with an aqueous solution containing an inorganic fluorine compound, a metal fluoride is preferably exemplified.
Specifically, for example, sodium fluoride, potassium fluoride, calcium fluoride, magnesium fluoride, sodium fluoride zirconate, potassium fluoride zirconate, sodium fluoride titanate, potassium fluoride titanate, zircon fluoride Ammonium acid, ammonium fluoride titanate, potassium fluoride titanate, zirconate fluoride, titanate fluoride, hexafluorosilicic acid, nickel fluoride, iron fluoride, phosphor fluoride, ammonium fluoride phosphate It is done. Of these, sodium fluorinated zirconate, sodium fluorinated titanate, fluorinated zirconic acid, and fluorinated titanic acid are preferable.

  The concentration of the inorganic fluorine compound in the aqueous solution is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, from the viewpoint of sufficiently sealing the micropores of the anodized film. Further, in terms of stain resistance, it is preferably 1% by mass or less, and more preferably 0.5% by mass or less.

  It is preferable that the aqueous solution containing an inorganic fluorine compound further contains a phosphate compound. When the phosphate compound is contained, the hydrophilicity of the surface of the anodized film is improved, so that on-machine developability and stain resistance can be improved.

Suitable examples of the phosphate compound include phosphates of metals such as alkali metals and alkaline earth metals.
Specifically, for example, zinc phosphate, aluminum phosphate, ammonium phosphate, diammonium hydrogen phosphate, ammonium dihydrogen phosphate, monoammonium phosphate, monopotassium phosphate, monosodium phosphate, dihydrogen phosphate Potassium, dipotassium hydrogen phosphate, calcium phosphate, sodium ammonium hydrogen phosphate, magnesium hydrogen phosphate, magnesium phosphate, ferrous phosphate, ferric phosphate, sodium dihydrogen phosphate, sodium phosphate, hydrogen phosphate Disodium, lead phosphate, diammonium phosphate, calcium dihydrogen phosphate, lithium phosphate, phosphotungstic acid, ammonium phosphotungstate, sodium phosphotungstate, ammonium phosphomolybdate, sodium phosphomolybdate, sodium phosphite , Tripolyphosphate Potassium, and sodium pyrophosphate. Of these, sodium dihydrogen phosphate, disodium hydrogen phosphate, potassium dihydrogen phosphate, and dipotassium hydrogen phosphate are preferable.
The combination of the inorganic fluorine compound and the phosphate compound is not particularly limited, but the aqueous solution contains at least sodium zirconate fluoride as the inorganic fluorine compound and contains at least sodium dihydrogen phosphate as the phosphate compound. Is preferred.

  The concentration of the phosphate compound in the aqueous solution is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, from the viewpoint of improving on-press developability and stain resistance. Further, in terms of solubility, it is preferably 20% by mass or less, and more preferably 5% by mass or less.

The ratio of each compound in the aqueous solution is not particularly limited, but the mass ratio of the inorganic fluorine compound and the phosphate compound is preferably 1/200 to 10/1, and preferably 1/30 to 2/1. Is more preferable.
Further, the temperature of the aqueous solution is preferably 20 ° C. or higher, more preferably 40 ° C. or higher, preferably 100 ° C. or lower, more preferably 80 ° C. or lower.
Further, the aqueous solution preferably has a pH of 1 or more, more preferably has a pH of 2 or more, preferably has a pH of 11 or less, and more preferably has a pH of 5 or less.
A method for sealing with an aqueous solution containing an inorganic fluorine compound is not particularly limited, and examples thereof include an immersion method and a spray method. These may be used alone or in combination, or may be used in combination of two or more.
Of these, the dipping method is preferred. When the treatment is performed using the dipping method, the treatment time is preferably 1 second or longer, more preferably 3 seconds or longer, more preferably 100 seconds or shorter, and 20 seconds or shorter. More preferred.

<2> Sealing treatment with water vapor The sealing treatment with water vapor includes, for example, a method in which pressurized or normal pressure water vapor is contacted with the anodized film continuously or discontinuously.
The temperature of the water vapor is preferably 80 ° C. or higher, more preferably 95 ° C. or higher, and preferably 105 ° C. or lower.
The pressure of the water vapor is preferably in a range (1.008 × 10 ^{5 to} 1.043 × 10 ⁵ Pa) from (atmospheric pressure−50 mmAq) to (atmospheric pressure + 300 mmAq).
Further, the time for which the water vapor is contacted is preferably 1 second or longer, more preferably 3 seconds or longer, 100 seconds or shorter, more preferably 20 seconds or shorter.

<3> Sealing treatment with hot water Examples of the sealing treatment with hot water include a method in which an aluminum plate on which an anodized film is formed is immersed in hot water.
The hot water may contain an inorganic salt (for example, phosphate) or an organic salt.
The temperature of the hot water is preferably 80 ° C. or higher, more preferably 95 ° C. or higher, and preferably 100 ° C. or lower.
Further, the time of immersion in hot water is preferably 1 second or longer, more preferably 3 seconds or longer, more preferably 100 seconds or shorter, and even more preferably 20 seconds or shorter.

  The hydrophilization treatment is described in US Pat. Nos. 2,714,066, 3,181,461, 3,280,734 and 3,902,734. There are alkali metal silicate methods. In this method, the support is subjected to immersion treatment or electrolytic treatment with an aqueous solution such as sodium silicate. In addition, the treatment with potassium zirconate fluoride described in JP-B 36-22063, U.S. Pat. Nos. 3,276,868, 4,153,461 and 4,689, And a method of treating with polyvinylphosphonic acid as described in each specification of No.272.

  The support preferably has a center line average roughness of 0.10 to 1.2 μm. Within this range, good adhesion to the image recording layer, good printing durability and good stain resistance can be obtained.

(Protective layer)
The lithographic printing plate precursor according to the invention preferably includes a protective layer (overcoat layer) on the image recording layer.
In addition to the function of suppressing the image formation inhibition reaction by blocking oxygen, the protective layer also has functions such as preventing scratches in the image recording layer and preventing ablation during high-illuminance laser exposure.
Hereinafter, components constituting the protective layer will be described.

  Usually, the exposure processing of a lithographic printing plate is carried out in the atmosphere. The image forming reaction in the image recording layer caused by the exposure process can be inhibited by low molecular compounds such as oxygen and basic substances present in the atmosphere. The protective layer prevents low molecular compounds such as oxygen and basic substances from entering the image recording layer, and as a result, suppresses image formation inhibition reaction in the air. Therefore, the property desired for the protective layer is to reduce the permeability of low-molecular compounds such as oxygen, and furthermore, the transparency of light used for exposure is good, and the adhesiveness with the image recording layer is excellent. And it can be easily removed in an on-press development process after exposure. The protective layer having such characteristics is described in, for example, US Pat. No. 3,458,311 and JP-B-55-49729.

As a material used for the protective layer, either a water-soluble polymer or a water-insoluble polymer can be appropriately selected and used. Specifically, for example, polyvinyl alcohol, modified polyvinyl alcohol, polyvinyl pyrrolidone, polyvinyl imidazole, polyacrylic acid, polyacrylamide, partially saponified product of polyvinyl acetate, ethylene-vinyl alcohol copolymer, water-soluble cellulose derivative, gelatin, Examples thereof include water-soluble polymers such as starch derivatives and gum arabic, and polymers such as polyvinylidene chloride, poly (meth) acrylonitrile, polysulfone, polyvinyl chloride, polyethylene, polycarbonate, polystyrene, polyamide, and cellophane.
These may be used in combination of two or more as required.

  Examples of relatively useful materials among the above materials include water-soluble polymer compounds having excellent crystallinity. Specifically, water-soluble acrylic resins such as polyvinyl alcohol, polyvinyl pyrrolidone, polyvinyl imidazole, and polyacrylic acid, gelatin, gum arabic, and the like are suitable. Among these, water can be applied as a solvent, and at the time of printing Polyvinyl alcohol, polyvinyl pyrrolidone, and polyvinyl imidazole are preferable from the viewpoint that they are easily removed by the fountain solution. Among them, polyvinyl alcohol (PVA) gives the best results for basic properties such as oxygen barrier properties and development removability.

  The polyvinyl alcohol that can be used in the protective layer may be partially substituted with esters, ethers, and acetals as long as they contain a substantial amount of unsubstituted vinyl alcohol units having the required water solubility. Similarly, a part may contain other copolymerization components. For example, various hydrophilic modification sites such as anion modification sites modified with anions such as carboxy groups and sulfo groups, cation modification sites modified with cations such as amino groups and ammonium groups, silanol modification sites, and thiol modification sites are randomly selected. Polyvinyl alcohol having various degrees of polymerization, the anion-modified site, the cation-modified site, the silanol-modified site, the thiol-modified site, the alkoxyl-modified site, the sulfide-modified site, and the ester modification of vinyl alcohol and various organic acids. Polyvinyl alcohol having various degrees of polymerization having various modified sites such as a site, an ester-modified site of the anion-modified site and alcohols, an epoxy-modified site, etc. at the polymer chain end is also preferably used.

Suitable examples of the modified polyvinyl alcohol include compounds having a hydrolysis degree of 71 to 100 mol% and a polymerization degree in the range of 300 to 2400. Specifically, PVA-105, PVA-110, PVA-117, PVA-117H, PVA-120, PVA-124, PVA-124H, PVA-CS, PVA-CST, PVA-HC manufactured by Kuraray Co., Ltd. , PVA-203, PVA-204, PVA-205, PVA-210, PVA-217, PVA-220, PVA-224, PVA-217EE, PVA-217E, PVA-220E, PVA-224E, PVA-405, PVA -420, PVA-613, L-8 and the like.
Moreover, as modified polyvinyl alcohol, all made by Kuraray Co., Ltd., KL-318, KL-118, KM-618, KM-118, SK-5102 having anion-modified sites, C having a cation-modified site. -318, C-118, CM-318, M-205, M-115 with terminal thiol modification sites, MP-103, MP-203, MP-102, MP-202 with terminal sulfide modification sites, high grade Examples thereof include HL-12E and HL-1203 having an ester-modified site with a fatty acid at the end, and R-1130, R-2105, R-2130 having other reactive silane-modified sites.

The protective layer preferably contains an inorganic layered compound, that is, a compound that is an inorganic compound, has a layered structure, and has a flat plate shape. By using such an inorganic layered compound in combination, the oxygen barrier property is further enhanced, and the film strength of the protective layer is further improved to improve scratch resistance, and the matte property is imparted to the specific protective layer. Can do.
Examples of the inorganic layered compound include, for example, the following general formula A (B, C) 2-5D ₄ O ₁₀ (OH, F, O) ₂ [where A is Li, K, Na, Ca, Mg, organic cation] Any one of B and C is any one of Fe (II), Fe (III), Mn, Al, Mg, and V, and D is Si or Al. And mica groups such as natural mica and synthetic mica, talc, teniolite, montmorillonite, saponite, hectorite, zirconium phosphate and the like represented by the formula 3MgO.4SiO.H ₂ O.

Among the mica compounds, natural mica includes muscovite, soda mica, phlogopite, biotite and sericite. In addition, examples of the synthetic mica include non-swelling mica such as fluorine phlogopite mica ₃ (AlSi ₃ O ₁₀ ) F ₂ , potassium tetrasilicon mica KMg _2.5 Si ₄ O ₁₀ ) F ₂ , and Na tetrasilicic mica NaMg _2.5 (Si ₄ O ₁₀ ) F ₂ , Na or Li Teniolite (Na, Li) Mg ₂ Li (Si ₄ O ₁₀ ) F ₂ , Montmorillonite-based Na or Li Hectorite (Na, Li) _1/8 Mg Swellable mica such as _2/5 Li _1/8 (Si ₄ O ₁₀ ) F ₂ can be used. Synthetic smectite is also useful.

Of the mica compounds, fluorine-based swellable mica, which is a synthetic layered compound, is particularly useful. That is, swellable clay minerals such as mica, montmorillonite, saponite, hectorite, bentonite, etc. have a laminated structure composed of unit crystal lattice layers with a thickness of about 10 to 15 mm, and metal atom substitution in the lattice is other than It is significantly larger than clay minerals. As a result, the lattice layer is deficient in positive charge, and in order to compensate for it, organic cations such as Li ⁺ , Na ⁺ , Ca ²⁺ , Mg ²⁺ , amine salts, quaternary ammonium salts, phosphonium salts and sulfonium salts are used between Adsorbs cations. These layered compounds swell with water. If shear is applied in this state, it will easily cleave and form a stable sol in water. Bentonite and swellable synthetic mica have a strong tendency and are useful in the present invention. In particular, swellable synthetic mica is preferably used from the viewpoint of availability and quality uniformity.

  The shape of the layered compound is a flat plate, and from the viewpoint of diffusion control, the thinner the better, the larger the plane size as long as it does not hinder the smoothness of the coated surface or the transmittance of actinic rays. . Accordingly, the aspect ratio is 20 or more, preferably 100 or more, particularly preferably 200 or more. The aspect ratio is the ratio of the thickness to the major axis of the particle, and can be measured, for example, from a projected view of the particle by a micrograph. The larger the aspect ratio, the greater the effect that can be obtained.

  As for the particle diameter of the layered compound, the average major axis is 0.3 to 20 μm, preferably 0.5 to 10 μm, particularly preferably 1 to 5 μm. When the particle diameter is smaller than 0.3 μm, the suppression of permeation of oxygen and moisture is insufficient, and the effect cannot be sufficiently exhibited. On the other hand, if it is larger than 20 μm, the dispersion stability in the coating solution is insufficient, resulting in a problem that stable coating cannot be performed. The average thickness of the particles is 0.1 μm or less, preferably 0.05 μm or less, particularly preferably 0.01 μm or less. For example, among inorganic layered compounds, the size of the swellable synthetic mica that is a representative compound is about 1 to 50 nm in thickness and about 1 to 20 μm in surface size.

  When particles of inorganic layered compounds having a large aspect ratio are contained in the protective layer in this way, the coating film strength is improved and oxygen and moisture permeation can be effectively prevented. Deterioration is prevented, and even when stored for a long time under high-humidity conditions, the storage stability of the planographic printing plate precursor does not deteriorate due to changes in humidity, and the storage stability is excellent.

Next, an example of a general dispersion method when a layered compound is used for the protective layer will be described.
First, 5 to 10 parts by mass of the swellable laminar compound mentioned above as a preferred laminar compound is added to 100 parts by mass of water, and the mixture is thoroughly swelled and swollen. Examples of the disperser used here include various mills that disperse mechanically by applying a direct force, a high-speed stirring disperser having a large shearing force, and a disperser that provides high-intensity ultrasonic energy. Specifically, ball mill, sand grinder mill, visco mill, colloid mill, homogenizer, tisol bar, polytron, homomixer, homo blender, ketdy mill, jet agitator, capillary emulsifier, liquid siren, electrostrictive ultrasonic generator, An emulsifying device having a Paulman whistle can be used. A dispersion of 5 to 10% by mass of the inorganic stratiform compound dispersed by the above method is highly viscous or gelled and has very good storage stability.
When preparing a coating solution for the protective layer using this dispersion, it is preferably prepared by diluting with water and stirring sufficiently, and then blending with a polymer solution such as polyvinyl alcohol.

  It is preferable that content of the inorganic stratiform compound in a protective layer is 5/1-1/100 by mass ratio with respect to the quantity of the said polymer used for a protective layer. Even when a plurality of kinds of inorganic layered compounds are used in combination, it is preferable that the total amount of these inorganic layered compounds is compatible with the above-described mass ratio.

  As other additives for the protective layer, for example, glycerin, dipropylene glycol, propionamide, cyclohexanediol, sorbitol and the like are added in an amount corresponding to several mass% with respect to the water-soluble or water-insoluble polymer to impart flexibility. be able to. Moreover, well-known additives, such as a water-soluble (meth) acrylic polymer and a water-soluble plasticizer, can be added for improving the physical properties of the film.

Further, the protective layer in the present invention is formed by using a coating solution for a protective layer as described later. This coating solution is used for improving the adhesion with the image recording layer and the stability over time of the coating solution. Known additives may be added.
That is, the protective layer coating solution includes an anionic surfactant, a nonionic surfactant, a cationic surfactant, and a fluorosurfactant for improving coating properties, specifically, sodium alkyl sulfate, alkyl sulfonic acid. Anionic surfactants such as sodium; amphoteric surfactants such as alkylaminocarboxylates and alkylaminodicarboxylates; nonionic surfactants such as polyoxyethylene alkylphenyl ether can be added. These surfactants can be added in an amount of 0.1 to 100% by mass relative to the water-soluble or water-insoluble polymer.

  In order to improve the adhesion to the image area, for example, JP-A-49-70702 and British Patent Application No. 1303578 include an acrylic polymer in a hydrophilic polymer mainly composed of polyvinyl alcohol. It is described that sufficient adhesion can be obtained by mixing 20 to 60% by mass of a water-based emulsion, a water-insoluble vinylpyrrolidone-vinyl acetate copolymer and the like, and laminating the mixture on an image recording layer. Any of these known techniques can be used in the present invention.

  Furthermore, a sensitizer such as the low molecular nitrogen compound or ammonium salt-containing polymer can be added to the protective layer. With these additions, a further effect of improving the inking property can be obtained. The amount of addition of the sensitizer to the protective layer is preferably in the range of 0.5 to 30% by mass.

Furthermore, other functions can be imparted to the protective layer. For example, by adding a colorant (for example, a water-soluble dye) that is excellent in the transparency of infrared rays used for exposure and that can efficiently absorb light of other wavelengths, safe light is not caused. Suitability can be improved. Further, for the purpose of controlling the slipperiness of the outermost surface of the lithographic printing plate precursor, it may contain spherical inorganic fine particles such as those added to the above-mentioned image recording layer. Preferred examples of the inorganic fine particles include silica, alumina, magnesium oxide, titanium oxide, magnesium carbonate, calcium alginate, and a mixture thereof. The inorganic fine particles preferably have an average particle size of 5 nm to 10 μm, and more preferably 50 nm to 3 μm. The inorganic fine particles as described above can be easily obtained as a commercial product such as a colloidal silica dispersion.
The content of the inorganic fine particles is preferably 40% by mass or less, and more preferably 20% by mass or less, based on the total solid content of the protective layer.

The protective layer is formed by applying and drying a protective layer coating solution prepared by dispersing or dissolving the protective layer component in a solvent on the image recording layer.
The coating solvent can be appropriately selected in relation to the polymer to be used, but when a water-soluble polymer is used, it is preferable to use distilled water or purified water.

The method for applying the protective layer is not particularly limited, and a known method such as the method described in US Pat. No. 3,458,311 or Japanese Patent Publication No. 55-49729 can be applied. .
Specifically, for example, when the protective layer is formed, a blade coating method, an air knife coating method, a gravure coating method, a roll coating coating method, a spray coating method, a dip coating method, a bar coating method, or the like is used.

The coating amount of the protective layer, the coating amount after drying is preferably in the range of 0.01 to 10 g / ^{m 2,} more preferably in the range of 0.02 to 3 g / ^{m 2,} and most preferably 0. in the range of 02~1g / ^{m 2.}

(Back coat layer)
After the surface treatment is performed on the support or after the undercoat layer is formed, a backcoat layer can be provided on the back surface of the support, if necessary.
As the back coat layer, for example, an organic polymer compound described in JP-A-5-45885, an organometallic compound or an inorganic metal compound described in JP-A-6-35174 is hydrolyzed and polycondensed. Preferable examples include a coating layer made of a metal oxide. Of these, the use of silicon alkoxy compounds such as Si (OCH ₃ ) ₄ , Si (OC ₂ H ₅ ) ₄ , Si (OC ₃ H ₇ ) ₄ , Si (OC ₄ H ₉ ) _4, etc. is inexpensive. It is preferable in that it is easily available.

[Plate making method]
The plate making of the lithographic printing plate precursor according to the invention is preferably carried out by an on-press development method. The on-press development method includes a step of image-exposing a lithographic printing plate precursor, a printing step of supplying an oil-based ink and an aqueous component and printing without performing any development treatment on the lithographic printing plate precursor after exposure, and And the unexposed portion of the lithographic printing plate precursor is removed during the printing process. Imagewise exposure may be performed on the printing machine after the lithographic printing plate precursor is mounted on the printing machine, or may be separately performed with a plate setter or the like. In the latter case, the exposed lithographic printing plate precursor is mounted on a printing machine without undergoing a development process. Thereafter, by using the printing machine and supplying the oil-based ink and the aqueous component and printing as it is, an on-press development process, that is, an image recording layer in an unexposed area is removed at an early stage of printing, Accordingly, the surface of the hydrophilic support is exposed to form a non-image part. As the oil-based ink and the aqueous component, ordinary lithographic printing ink and fountain solution are used.
This will be described in more detail below.

In the present invention, the light source used for image exposure is preferably a laser. Although the laser used for this invention is not specifically limited, The solid laser and semiconductor laser etc. which irradiate infrared rays with a wavelength of 760-1200 nm are mentioned suitably.
Regarding the infrared laser, the output is preferably 100 mW or more, the exposure time per pixel is preferably within 20 microseconds, and the irradiation energy amount is preferably 10 to 300 mJ / cm ² . In the laser, it is preferable to use a multi-beam laser device in order to shorten the exposure time.

  The exposed lithographic printing plate precursor is mounted on a plate cylinder of a printing press. In the case of a printing press equipped with a laser exposure device, image exposure is performed after a lithographic printing plate precursor is mounted on a plate cylinder of the printing press.

  When printing is performed by supplying dampening water and printing ink to the lithographic printing plate precursor exposed imagewise, the image recording layer cured by exposure has a printing ink acceptance having an oleophilic surface in the exposed portion of the image recording layer. Forming part. On the other hand, in the unexposed area, the uncured image recording layer is removed by dissolution or dispersion by the supplied dampening water and / or printing ink, and a hydrophilic surface is exposed in that area. As a result, the fountain solution adheres to the exposed hydrophilic surface, and the printing ink is deposited on the image recording layer in the exposed area and printing is started.

Here, dampening water or printing ink may be supplied to the printing plate first, but printing is first performed in order to prevent the dampening water from being contaminated by the removed image recording layer components. It is preferable to supply ink.
In this way, the lithographic printing plate precursor according to the invention is developed on the machine on an offset printing machine and used as it is for printing a large number of sheets.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited to these.

1. Preparation of interleaving paper (1) Preparation of interleaving paper (1) Beating bleached kraft pulp and diluting it to a concentration of 4% by mass, 0.4% by mass of neutral sizing agent of alkyl ketene dimer (AKD) In addition, 5.0% by mass of calcium carbonate was added. This paper stock was coated with 3.0% by weight of a paper strength agent containing starch as the main component, and then paper-made. The paper was nipped at a linear pressure of 18 kg / cm using a resin roll with a soft calender with two nips. PH 7.0, center line surface roughness measured by the above method of 3.2 μm, chloride ion content 0.05 mass%, calcium content 0.30 mass%, basis weight 48 g / m ² , moisture An interleaf paper 1 having an amount of 5.5% by mass was produced.

(2) Manufacture of interleaving paper (2) The calendering process for the production of interleaving paper (1) described above was carried out using a metal roll and an elastic roll with a super calender with 10 nips, a roll temperature of 80 ° C., and a nip linear pressure of 220 kg. A slip sheet (2) was prepared in the same manner as the slip sheet (1) except that calendering was performed at / cm. The pH was 7.0, the center line surface roughness was 2.6 μm, the chloride ion content was 0.06 mass%, the calcium content was 0.30 mass%, the basis weight was 48 g / m ² , and the water content was 5.7 mass%. .

(3) Preparation of interleaving paper (3) Except that the bleached kraft pulp of the above interleaving paper (2) was replaced with bleached kraft pulp with further increased whiteness, the same as the above interleaving paper (2). Interleaving paper (3) was produced. The pH was 7.0, the center line surface roughness was 2.6 μm, the chloride ion content was 0.35 mass%, the calcium content was 0.30 mass%, the basis weight was 48 g / m ² , and the water content was 6.0 mass%. .

(4) Preparation of interleaving paper (4) Beating bleached kraft pulp and adding 0.4% by mass of rosin sizing agent to the stock diluted to a concentration of 4% by mass, and adjusting the pH of aluminum sulfate to 5.0 Added until. The paper stock was coated with 3.0% by weight of a paper strength agent containing starch as a main component, and papermaking was performed, and the same calendering as in the production of the interleaving paper (1) was performed, and the center line surface roughness was 2.8 μm. A slip sheet (4) having a chloride ion content of 0.09% by mass, a calcium content of 0.02% by mass, a basis weight of 42 m ² and a moisture content of 7.0% by mass was produced.

(5) Preparation of interleaving paper (5) Interleaving paper (5) was prepared in the same manner as the above interleaving paper (2) except that the raw material for preparing the interleaving paper (2) was adjusted to 6% by mass. Was made. The pH was 7.0, the center line surface roughness was 2.9 μm, the chloride ion content was 0.08 mass%, the calcium content was 0.30 mass%, the basis weight was 58 g / m ² , and the water content was 7.5 mass%. .

(6) Production of interleaf (6) Same as the production of interleaf (4) except that the calendering step for producing the interleaf (4) is replaced with the calendering step for the interleaf (2). Thus, an interleaf paper (6) was produced. Interleaving paper with pH 5.0, centerline surface roughness 2.5 μm, chloride ion content 0.40 mass%, calcium content 0.08 mass%, basis weight 59 g / m ² , moisture content 7.0 mass% (6) was produced.

(7) Manufacture of interleaf paper (7) In the calendering process for the production of interleaving paper (2), the calendering was performed with a super calender having 14 nips, a roll temperature of 90 ° C., and a nip linear pressure of 250 kg / cm. Except for the above, an interleaf (7) was prepared in the same manner as the interleaf (2). The pH was 7.0, the center line surface roughness was 2.2 μm, the chloride ion content was 0.08 mass%, the calcium content was 0.28 mass%, the basis weight was 54 g / m ² , and the water content was 5.5 mass%. .

(8) Preparation of interleaving paper (8) Beating the bleached kraft pulp of the interleaving paper (4) above, adding 0.6% by mass of rosin sizing agent to the paper stock diluted to a concentration of 5% by mass, and aluminum sulfate. Was added until the pH was 5.0. The paper stock was coated with 2.0% by weight of a paper strength agent containing starch as a main component, and papermaking was performed, and the same calendering as in the production of the interleaving paper (4) was performed, and the center line surface roughness was 4.2 μm. A slip sheet (8) having a chloride ion content of 0.9% by mass, a calcium content of 0.08% by mass, a basis weight of 50 g / m ² , and a moisture content of 7.0% by mass was produced.

(9) Preparation of interleaving paper (9) The raw material stock of the above interleaving paper (1) is adjusted to 6% by mass, and in the calendering process, the number of nips is 1 soft calender and 15 kg using a resin roll. A slip sheet (9) was prepared in the same manner as the slip sheet (1) except that nip was performed at a linear pressure of / cm. The pH was 7.0, the center line surface roughness was 6.1 μm, the chloride ion content was 0.08 mass%, the calcium content was 0.28 mass%, the basis weight was 58 g / m ² , and the water content was 7.8 mass%. .

2. Preparation of lithographic printing plate precursor (1) (1) Preparation of support In order to remove rolling oil on the surface of an aluminum plate (material JIS A 1050) having a thickness of 0.3 mm, a 10 mass% sodium aluminate aqueous solution is used. After degreasing treatment at 30 ° C. for 30 seconds, the aluminum surface was sanded using ^three bundle-planted nylon brushes with a bristle diameter of 0.3 mm and a pumice-water suspension (specific gravity 1.1 g / cm ³ ) with a median diameter of 25 μm. Conspicuous and washed well with water. This plate was etched by being immersed in a 25 mass% sodium hydroxide aqueous solution at 45 ° C for 9 seconds, washed with water, further immersed in 20 mass% nitric acid at 60 ° C for 20 seconds, and washed with water. The etching amount of the grained surface at this time was about 3 g / m ² .

Next, an electrochemical roughening treatment was performed continuously using an alternating voltage of 60 Hz. The electrolytic solution at this time was a 1% by mass nitric acid aqueous solution (containing 0.5% by mass of aluminum ions) and a liquid temperature of 50 ° C. The AC power source waveform is electrochemical roughening treatment using a trapezoidal rectangular wave alternating current with a time ratio TP of 0.8 msec until the current value reaches a peak from zero, a duty ratio of 1: 1, and a trapezoidal rectangular wave alternating current. Went. Ferrite was used for the auxiliary anode. The current density was 30 A / dm ² at the peak current value, and 5% of the current flowing from the power source was shunted to the auxiliary anode.
The amount of electricity in the nitric acid electrolysis was 175 C / dm ² when the aluminum plate was the anode. Then, water washing by spraying was performed.

Next, a 0.5% by mass hydrochloric acid aqueous solution (containing 0.5% by mass of aluminum ions) and an electrolytic solution having a liquid temperature of 50 ° C. and nitric acid electrolysis under the condition of an electric quantity of 50 C / dm ² when the aluminum plate is an anode. In the same manner as above, an electrochemical surface roughening treatment was performed, followed by washing with water by spraying.
Next, the plate was provided with a DC anodized film of 2.5 g / m ² at a current density of 15 A / dm ² using 15% by mass sulfuric acid (containing 0.5% by mass of aluminum ions) as an electrolyte, and then washed with water. Dried.
Then, in order to ensure the hydrophilic property of a non-image part, the silicate process was performed for 12 second at 70 degreeC using 2.5 mass% 3 sodium silicate aqueous solution. The adhesion amount of Si was 10 mg / m ² . Then, it washed with water and the support body (1) was obtained. The centerline average roughness (Ra) of this substrate was measured using a needle having a diameter of 2 μm and found to be 0.51 μm.

(2) Formation of Undercoat layer (1) Next, on the support (1), the following undercoat solution (1) dry coating amount was applied so as to be 28 mg / m ^2, the undercoat layer (1) Provided.

<Coating liquid for undercoat layer (1)>
-Undercoat layer compound (1) having the following structure (Mw 100,000) 0.18 g
・ Hydroxyethyliminodiacetic acid 0.10g
・ Methanol 55.24g
・ Ion-exchanged water 6.15g

(3) Formation of image recording layer (1) On the undercoat layer formed as described above, an image recording layer coating solution (1) having the following composition was bar coated, followed by oven drying at 100 ° C for 60 seconds, An image recording layer (1) having a dry coating amount of 1.0 g / m ² was formed.
The image recording layer coating solution (1) was obtained by mixing and stirring the following photosensitive solution (1) and microgel solution (1) immediately before coating.

<Photosensitive solution (1)>
-Binder polymer (1) (Mw 70,000) [the following structure] 0.240 g
Infrared absorber (1) [the following structure] 0.030 g
-Radical polymerization initiator (1) [the following structure] 0.162 g
Polymerizable compound tris (acryloyloxyethyl) isocyanurate (NK ester A-9300, manufactured by Shin-Nakamura Chemical Co., Ltd.) 0.192 g
・ Low molecular weight hydrophilic compound Tris (2-hydroxyethyl) isocyanurate
0.028g
・ Low molecular weight hydrophilic compound (1) [the following structure] 0.050 g
-Sensitizing agent Phosphonium compound (1) [the following structure] 0.055 g
・ Sensitizer Benzyl-dimethyl-octylammonium ・ PF ₆ salt 0.018g
・ Fluorine-based surfactant (1) (Mw 13,000) [the following structure] 0.008 g
・ Methyl ethyl ketone 1.091g
・ 1-methoxy-2-propanol 8.609g

<Microgel solution (1)>
・ Microgel (1) 2.640 g
・ Distilled water 2.425g

  The structures of the infrared absorbent (1), the phosphonium compound (1), the low molecular weight hydrophilic compound (1), and the fluorosurfactant (1) are as shown below.

  Said microgel (1) is synthesize | combined as follows.

<Synthesis of Microgel (1)>
As oil phase components, trimethylolpropane and xylene diisocyanate adduct (Mitsui Takeda Chemical Co., Ltd., Takenate D-110N) 10 g, pentaerythritol triacrylate (Nippon Kayaku Co., Ltd., SR444) 3.15 g, And 0.1 g of Pionein A-41C (manufactured by Takemoto Yushi Co., Ltd.) was dissolved in 17 g of ethyl acetate. As an aqueous phase component, 40 g of a 4% by mass aqueous solution of PVA-205 was prepared. The oil phase component and the aqueous phase component were mixed and emulsified for 10 minutes at 12,000 rpm using a homogenizer. The obtained emulsion was added to 25 g of distilled water, stirred at room temperature for 30 minutes, and then stirred at 50 ° C. for 3 hours. The microgel solution thus obtained was diluted with distilled water to a solid content concentration of 15% by mass, and this was designated as the microgel (1). When the average particle size of the microgel was measured by a light scattering method, the average particle size was 0.2 μm.

(4) Formation of protective layer (1) On the image recording layer formed as described above, a protective layer coating solution (1) having the following composition was further bar-coated, followed by oven drying at 120 ° C for 60 seconds. A protective layer (1) having a dry coating amount of 0.17 g / m ² was formed to obtain a lithographic printing plate precursor (1).

<Coating liquid for protective layer (1)>
・ Inorganic layered compound dispersion (1) 2.5 g
-Polyvinyl alcohol (Nippon Synthetic Chemical Industry Co., Ltd. CKS50, sulfonic acid modification,
Saponification degree 99 mol% or more, polymerization degree 300) 6% by mass aqueous solution 0.75 g
・ Polyvinyl alcohol (PVA-405 manufactured by Kuraray Co., Ltd.)
Saponification degree 81.5 mol% Polymerization degree 500) 6% by weight aqueous solution 0.30 g
・ Surfactant manufactured by Nippon Emulsion Co., Ltd.
(Emalex 710) 1% by weight aqueous solution 1.20 g
・ Ion-exchanged water 6.0g

(Preparation of inorganic layered compound dispersion (1))
6.4 g of synthetic mica Somasif ME-100 (manufactured by Coop Chemical Co., Ltd.) was added to 193.6 g of ion-exchanged water, and dispersed using an homogenizer until the average particle size (laser scattering method) became 3 μm. The aspect ratio of the obtained dispersed particles was 100 or more.

2. Preparation of lithographic printing plate precursor (2) (1) Formation of image recording layer (2) A lithographic printing plate precursor (1) except that the image recording layer coating solution (1) is changed to the image recording layer coating solution (2) shown below. A lithographic printing plate precursor (2) was prepared in the same manner as in 1).

<Image recording layer coating solution (2)>
・ Binder polymer (1) 0.50g
・ Infrared absorber (2) [the following structure] 0.05 g
・ Radical polymerization initiator (1) 0.20g
Polymerizable compound (Aronix M-215, manufactured by Toa Gosei Co., Ltd.,
Isocyanuric acid EO-modified diacrylate) 1.00 g
・ Low molecular hydrophilic compound sodium n-heptylsulfonate 0.05 g
・ Sensitizer Benzyl-dimethyl-octylammonium ・ PF ₆ salt 0.018g
-Sensitizer Ammonium group-containing polymer (Exemplified compound (20) of the present specification, reduced specific viscosity 54 cSt / g / ml) 0.035 g
・ Fluorosurfactant (1) (Mw 13,000) 0.10 g
・ Methyl ethyl ketone 18.0g

[Examples 1-12 and Comparative Examples 1-18]
The obtained interleaving papers (1) to (9) and the planographic printing plate precursors (1) to (3) are stacked in a stack of 50 sheets alternately in an environment of 25 ° C. and 45% RH in the combination shown in Table 2. Thus, a laminate was produced. Further, a contact ball having a basis weight of about 800 g / m ² was placed on the upper and lower ends of the laminate, and packed with moisture-proof interior paper (aluminum craft paper). Using the planographic printing plate precursor in the package, the sensitivity, on-machine developability, minute spot-like stains, and printing durability were evaluated as follows. The results are shown in Table 2.

(1) On-press developability after aging of the laminate The package of the obtained lithographic printing plate precursor was forcibly aged by placing it in a constant temperature and humidity chamber at 60 ° C. and 50% RH for 48 hours. The package taken out after 48 hours was cooled to room temperature and then opened and used for subsequent evaluation.
A lithographic printing plate precursor taken out from a package not subjected to forced aging, and a lithographic printing plate precursor taken out from a package after forced aging to the outer surface of a Luxel PLANETTER T-6000III manufactured by FUJIFILM Corporation equipped with an infrared semiconductor laser. The exposure was performed under the conditions of a drum rotation speed of 1000 rpm, a laser output of 70%, and a resolution of 2400 dpi. The exposure image is a solid image, a thin line image (a test chart in which the thickness of a thin line (thin line image portion in the non-image portion) is changed every 2 μm from 4 μm to 30 μm), and a 50% halftone dot of a 20 μm dot FM screen A chart was included.
The obtained exposed original plate was attached to a plate cylinder of a printing machine LITHRONE 26 manufactured by Komori Corporation without developing. Equality-2 (manufactured by FUJIFILM Corporation) / tap water = 2/98 (volume ratio) dampening water and Values-G (N) black ink (manufactured by Dainippon Ink & Chemicals, Inc.) After dampening water and ink were supplied by the standard automatic printing start method of LITHRONE 26 and developed on the machine, 100 sheets were printed on Tokuhishi Art (76.5 kg) paper at a printing speed of 10,000 sheets per hour.

  The number of printing papers required until the ink in the non-image area on the printed material was completely removed was measured as on-machine developability. These results are shown in Table 2.

(2) Sensitivity After the on-press developability was evaluated, printing was continued up to 500 sheets. Fine line reproducibility was used as a method for evaluating the sensitivity in the image exposure. That is, it was observed with a magnifying glass of 25 times how thick the exposed thin line image was reproduced on the printed matter. A smaller value obtained by observation indicates that a finer fine line is well formed, indicating that the sensitivity is high. These results are shown in Table 2.

(3) Minute spot-like stains The printed matter after the forced aging in which the sensitivity was evaluated was further evaluated for minute spot-like stains. This was evaluated by observing a non-image portion of 100 cm ² with a magnifying glass at a magnification of 10 times and counting spot-like stains having a diameter of 50 μm or more. Smaller values indicate better results and up to 10 are acceptable levels. These results are shown in Table 2.

(4) Printing durability After the above evaluation was performed on the lithographic printing plate precursor not subjected to forced aging, printing was further continued. As the number of printed sheets was increased, the image recording layer was gradually worn out, so that the ink density on the printed material decreased. Printing durability was evaluated using the number of printed copies when the value measured by the Gretag densitometer for the 50% halftone dot area ratio of the FM screen in the printed material was 5% lower than the measured value for the 100th printed sheet. . The results are shown in Table 2.

  As can be seen from Table 2, according to the present invention, even when the lithographic printing plate precursor laminate is aged, good sensitivity and on-press developability are exhibited, the occurrence of minute spot-like stains is suppressed, and the printing durability is good. A laminate of a lithographic printing plate precursor can be provided.

It is a figure which shows the example of a packaging structure of the lithographic printing plate precursor laminated body of this invention. It is a figure which shows the example of a packaging structure of the lithographic printing plate precursor laminated body of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Planographic printing plate precursor 12 Laminated body 14 Interleaf paper 16 Interior paper 18 Planographic printing plate precursor packaging structure 22 Contact ball 24 Adhesive tape

Claims (7)

  (A) Infrared absorber, (B) radical polymerization initiator, and (C) polymerizable compound are contained on the support, and printing ink and dampening water are supplied to remove unexposed portions. A lithographic printing plate precursor having an image recording layer that can be formed, and a slip sheet having a chloride ion content of 0.5% by mass or less and a center line average roughness (Ra) of 2.4 μm to 5 μm in the slip sheet A laminate of lithographic printing plate precursors, characterized in that and are alternately stacked and accumulated.   The laminate of a lithographic printing plate precursor according to claim 1, wherein the calcium content in the slip sheet is 0.15% by mass to 0.5% by mass. Stack of lithographic printing plate precursor as claimed in claim 1 or 2, wherein the basis weight of the interleaving paper is ^{40g / m 2 ~55g / m 2} .   The lithographic printing plate precursor laminate according to any one of claims 1 to 3, wherein the image recording layer further contains microcapsules or microgels.   The lithographic printing plate precursor as claimed in any one of claims 1 to 4, wherein the lithographic printing plate precursor has a protective layer on the image recording layer.   The image recording layer contains at least one low-molecular compound selected from the group consisting of polyols, alkyl sulfates, alkyl sulfonates, and betaines. A laminate of the lithographic printing plate precursor as described in 1.   The lithographic printing plate precursor according to any one of claims 1 to 6, wherein the lithographic printing plate precursor has an undercoat layer between the support and the image recording layer.

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