CN112930266B

CN112930266B - Lithographic printing plate precursor, method for producing lithographic printing plate, and lithographic printing method

Info

Publication number: CN112930266B
Application number: CN201980071585.7A
Authority: CN
Inventors: 野越启介; 阪口彬
Original assignee: Fujifilm Corp
Current assignee: Fujifilm Corp
Priority date: 2018-10-31
Filing date: 2019-10-31
Publication date: 2023-02-28
Anticipated expiration: 2039-10-31
Also published as: EP3875282A1; JP2020069790A; CN112930266A; EP3875282A4

Abstract

The invention provides a lithographic printing plate precursor, which comprises an image recording layer on a support, wherein the image recording layer comprises an infrared absorbent represented by formula 1-1, a polymerization initiator and a polymerizable compound. R in formula 1-1 and formula 2 is shown in the specification ¹ 、R ₁₁ ～R ₁₈ 、n ₁₁ ～n ₁₄ 、L、Za、A ₁ And A ₂ The details of (a).

Description

Lithographic printing plate precursor, method for producing lithographic printing plate, and lithographic printing method

Technical Field

The present invention relates to a lithographic printing plate precursor, a method for producing a lithographic printing plate, and a lithographic printing method.

Background

In general, a lithographic printing plate is composed of an oleophilic image portion that accepts ink during printing and a hydrophilic non-image portion that accepts fountain solution. Lithography is the following method: printing is performed by using the property of mutual repulsion between water and oil-based ink, wherein a difference in ink adhesion occurs on the surface of a lithographic printing plate by using an oleophilic image portion of the lithographic printing plate as an ink-receiving portion and a hydrophilic non-image portion as a fountain solution-receiving portion (ink-non-receiving portion), and the ink is transferred to a printing object such as paper after the ink is adhered only to the image portion.

In order to produce such a lithographic printing plate, 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. A lithographic printing plate is generally obtained by plate making as follows: after exposure of an original such as a high contrast film to a lithographic printing plate precursor, a portion of the original to be an image recording layer is left, and an excess image recording layer other than the image recording layer is removed by dissolving with an alkaline developer or an organic solvent to expose the surface of a hydrophilic support to form a non-image portion.

Further, due to the increasing interest in the global environment, environmental problems associated with waste liquid accompanying wet treatment such as development treatment become apparent.

With respect to the above environmental problems, simplification and no processing of development or plate making are pointed out. As one of the simple manufacturing methods, a method called "on-press development" is performed. Namely, the following method is used: the lithographic printing plate precursor is directly mounted on a printing press without conventional development after exposure, and removal of an unnecessary portion of the image recording layer is performed at an initial stage of a normal printing process.

In the present invention, a lithographic printing plate precursor that can be used for such on-press development is referred to as an "on-press development type lithographic printing plate precursor".

As a heat-sensitive image forming element used in a conventional lithographic printing plate precursor, for example, a heat-sensitive image forming element described in patent document 1 can be mentioned.

Patent document 1 describes a thermosensitive image forming element containing an IR dye having a structure according to formula I.

[ chemical formula 1]

(formula I)

In the formula (I), the compound is shown in the specification, ⁺ Y ¹ = a composition consisting of:

[ chemical formula 2]

One of them represents, Y ² -consisting of the following structure:

[ chemical formula 3]

Represents that n is 0, 1,2 or 3,p and q is 0, 1 or 2,R respectively ¹ And R ² Independently a hydrocarbon group which may be optionally substituted, or the above R ¹ 、R ² 、R ^d Or R ^a Two of the radicals containing the atoms required to form together a cyclic structure, R ^d At least one of the radicals being converted into a radical R than mentioned above by a chemical reaction caused by IR-irradiation or exposure to heat ^d Radical of a strong electron-donor group or R ^a At least one of the groups is a group which is converted into a group which is an electron-donor stronger than the above-mentioned Ra by a chemical reaction due to IR-irradiation or exposure to heat, and the other R is ^d And R ^a The groups are independently selected from hydrogen atom, halogen atom, -R ^e 、-OR ^f 、-SR ^g and-NR ^u R ^v In which R is ^e 、R ^f 、R ^g 、R ^u And R ^v Independently an aliphatic hydrocarbon group which may be optionally substitutedOr (hetero) aryl which may be substituted as the case may be, and the above conversion is characterized by increasing the integrated light absorption of the dye between 400 and 700 nm.

As the color developing composition used for the conventional lithographic printing plate precursor, for example, the color developing composition described in patent document 2 can be mentioned.

Patent document 2 describes a color developing composition containing a compound represented by the following formula 1.

[ chemical formula 4]

In the formula 1, R ¹ Denotes R by thermal or infrared exposure ¹ A group in which-O bonds are broken, R ² And R ³ Each independently represents a hydrogen atom or an alkyl group, R ² And R ³ May be linked to each other to form a ring, ar ¹ And Ar ² Each independently represents a group forming a benzene ring or a naphthalene ring, Y ¹ And Y ² Each independently represents an oxygen atom, a sulfur atom, -NR ⁰ Or a dialkylmethylene group, R ⁴ And R ⁵ Each independently represents an alkyl group, R ⁶ ～R ⁹ Each independently represents a hydrogen atom or an alkyl group, R ⁰ Represents a hydrogen atom, an alkyl group or an aryl group, and Za represents a counter ion for neutralizing a charge.

Patent document 1: japanese Kokai publication No. 2008-544053

Patent document 2: international publication No. 2016/027886

Disclosure of Invention

Technical problem to be solved by the invention

An object of one embodiment of the present invention is to provide a lithographic printing plate precursor that can provide a lithographic printing plate having excellent printing durability even when a UV ink is used.

Another object of the present invention is to provide a method for producing a lithographic printing plate using the lithographic printing plate precursor and a lithographic printing method using the lithographic printing plate precursor.

Means for solving the technical problem

The means for solving the above problem includes the following means.

< 1 > a lithographic printing plate precursor having an image-recording layer on a support,

the image recording layer contains an infrared absorber represented by the following formula 1-1, a polymerization initiator, and a polymerizable compound.

[ chemical formula 5]

In the formula 1-1, R ¹ Represents a group represented by the following formula 2, R ₁₁ ～R ₁₈ Each independently represents a hydrogen atom, a halogen atom, -R ^a 、-OR ^b 、-SR ^c or-NR ^d R ^e ，R ^a ～R ^e Each independently represents a hydrocarbon group, A ₁ 、A ₂ And a plurality of R ₁₁ ～R ₁₈ May be linked to form a monocyclic or polycyclic ring, A ₁ And A ₂ Each independently represents an oxygen atom, a sulfur atom or a nitrogen atom, n ₁₁ And n ₁₂ Each independently represents an integer of 0 to 5, wherein n ₁₁ And n ₁₂ Is 2 or more, n ₁₃ And n ₁₄ Each independently represents 0 or 1,L represents an oxygen atom, a sulfur atom or-NR ¹⁰ -，R ¹⁰ Represents a hydrogen atom, an alkyl group or an aryl group, and Za represents a counter ion for neutralizing a charge.

[ chemical formula 6]

In formula 2, R ^Z Represents an alkyl group, and the wavy line represents a bonding site with the group represented by L in the above formula 1-1.

< 2 > the lithographic printing plate precursor according to the above < 1 >, wherein the infrared absorber is a cyanine dye represented by the following formula 1-2.

[ chemical formula 7]

In the formula 1-2, R ¹ Represents a group represented by the following formula 2, R ² And R ³ Each independently represents a hydrogen atom or an alkyl group, R ² And R ³ May be linked to each other to form a ring, ar ¹ And Ar ² Each independently represents a group forming a benzene ring or a naphthalene ring, Y ¹ And Y ² Each independently represents an oxygen atom, a sulfur atom, -NR ⁰ Or a dialkylmethylene group, R ⁰ Represents a hydrogen atom, an alkyl group or an aryl group, R ⁴ And R ⁵ Each independently represents an alkyl group, -CO ₂ M radical or-PO ₃ M ₂ M represents a hydrogen atom, a sodium atom, a potassium atom or an onium group, R ⁶ ～R ⁹ Each independently represents a hydrogen atom or an alkyl group, L represents an oxygen atom, a sulfur atom or-NR ¹⁰ -，R ¹⁰ Represents a hydrogen atom, an alkyl group or an aryl group, and Za represents a counter ion for neutralizing a charge.

[ chemical formula 8]

In formula 2, R _Z Represents an alkyl group, and the wavy line represents a bonding site with a group represented by L in the above formula 1-2.

< 3 > the lithographic printing plate precursor according to the above < 1 > or < 2 >, wherein L in the above formula 1-1 represents a sulfur atom or-NR > ¹⁰ -, the above R ¹⁰ Represents a hydrogen atom, an alkyl group or an aryl group.

< 4 > the lithographic printing plate precursor according to the above < 3 >, wherein R in the above formula 1-2 ⁴ And R ⁵ Each independently represents-R ^w4 -SO ₃ M represents a hydrogen atom, a sodium atom, a potassium atom or an onium groupR ^w4 Represents a single bond or an alkylene group having 1 to 12 carbon atoms.

< 5 > the lithographic printing plate precursor according to any one of the above < 1 > to < 4 >, wherein L in the above formula 1-1 is an oxygen atom.

< 6 > the lithographic printing plate precursor according to any of the above < 1 > to < 5 >, wherein the polymerizable compound has a polymerizable group having 3 or more functions.

< 7 > the lithographic printing plate precursor according to any one of the above < 1 > to < 5 >, wherein the polymerizable compound has a polymerizable group having 7 or more functions.

< 8 > the lithographic printing plate precursor according to any one of the above < 1 > to < 5 >, wherein the polymerizable compound has a polymerizable group having 10 or more functions.

< 9 > the lithographic printing plate precursor according to any one of the above < 1 > to < 8 >, wherein the polymerizable compound has an ethylenically unsaturated bond equivalent of 200g/mol or less.

< 10 > the lithographic printing plate precursor according to any of the above < 1 > to < 9 >, wherein the CLogP of the polymerizable compound is 6 or less.

< 11 > the lithographic printing plate precursor according to any one of the above < 1 > to < 10 >, wherein the polymerizable group of the polymerizable compound comprises a vinyl group or a (meth) acryloyl group.

< 12 > the lithographic printing plate precursor according to any of the above < 1 > to < 11 >, wherein the above image-recording layer further comprises a binder polymer,

the binder polymer has a structural unit formed of an aromatic vinyl compound.

< 13 > the lithographic printing plate precursor according to any of the above < 1 > to < 12 >, wherein the above image-recording layer further comprises polymer particles.

< 14 > the lithographic printing plate precursor according to the above < 13 >, wherein the above polymer particles comprise polymer particles having a hydrophilic group.

< 15 > the lithographic printing plate precursor according to the above < 14 >, wherein the above polymer particles have a polyalkylene oxide structure as the above hydrophilic group.

< 16 > the lithographic printing plate precursor according to any one of the above < 1 > to < 15 >, wherein the above-mentioned polymerization initiator comprises at least one polymerization initiator selected from the group consisting of an electron donating polymerization initiator and an electron accepting polymerization initiator.

< 17 > the lithographic printing plate precursor according to the above < 16 >, wherein the above electron-donating polymerization initiator is an onium salt compound.

< 18 > the lithographic printing plate precursor according to the above < 16 > or < 17 >, wherein the HOMO of the electron-donating polymerization initiator is-6.0 eV or more.

< 19 > the lithographic printing plate precursor according to any one of the above < 16 > to < 18 >, wherein the LUMO of the above electron accepting type polymerization initiator is-3.0 eV or less.

< 20 > the lithographic printing plate precursor according to any one of the above < 16 > to < 19 >, wherein the above-mentioned polymerization initiator is a compound forming a counter salt from the above-mentioned electron-donating polymerization initiator and the above-mentioned electron-accepting polymerization initiator.

< 21 > the lithographic printing plate precursor according to any of the above < 1 > to < 20 >, wherein the above image-recording layer further comprises an acid developer.

< 22 > the lithographic printing plate precursor according to any of the above < 1 > to < 21 >, wherein an overcoat layer is further provided on the image-recording layer.

< 23 > the lithographic printing plate precursor according to any one of the above < 1 > to < 22 >, wherein the support has an aluminum plate and an anodic oxide film of aluminum disposed on the aluminum plate,

the anodic oxide film is positioned closer to the image recording layer side than the aluminum plate,

the anodic oxidation coating has micropores extending in a depth direction from a surface on the image recording layer side,

the micropores have an average diameter of more than 10nm and not more than 100nm on the surface of the anodic oxide film.

< 24 > the lithographic printing plate precursor according to the above < 23 >, wherein the micropores comprise large-diameter holes extending from the surface of the anodized film to a depth of 10nm to 1,000nm and small-diameter holes communicating with bottoms of the large-diameter holes and extending from the communicating positions to a depth of 20nm to 2,000nm,

the average diameter of the large-diameter pores on the surface of the anodic oxide film is 15nm to 100nm,

the average diameter of the small-diameter hole portion at the communication position is 13nm or less.

< 25 > a method of making a lithographic printing plate, the method comprising: exposing the lithographic printing plate precursor described in any of the above-mentioned < 1 > to < 24 > to an image; and

and a step of supplying at least one selected from the group consisting of printing ink and dampening solution to the printing press to remove the image recording layer of the non-image portion.

< 26 > a lithographic method comprising: exposing the lithographic printing plate precursor described in any of the above-mentioned < 1 > to < 24 > to an image;

a step of supplying at least one selected from the group consisting of printing ink and dampening solution to remove the image recording layer of the non-image portion on the printing press to produce a lithographic printing plate; and

a step of performing printing by the obtained lithographic printing plate.

Effects of the invention

According to one embodiment of the present invention, a lithographic printing plate precursor capable of obtaining a lithographic printing plate excellent in the brushing resistance even when a UV ink is used can be provided.

Further, according to another embodiment of the present invention, there can be provided a method for manufacturing a lithographic printing plate using the lithographic printing plate precursor and a lithographic printing method using the lithographic printing plate precursor.

Drawings

Fig. 1 is a schematic cross-sectional view of an embodiment of an aluminum support.

Fig. 2 is a schematic cross-sectional view of another embodiment of an aluminum support.

Fig. 3 is a schematic view of an anodizing apparatus used in an anodizing treatment performed when an aluminum support is produced.

Detailed Description

The present invention will be described in detail below. The following description of the constituent elements is made in accordance with the exemplary embodiments of the present invention, but the present invention is not limited to such embodiments.

In the present specification, "to" indicating a numerical range is used in a sense including numerical values described before and after the range as a lower limit value and an upper limit value.

In the numerical ranges recited in the present invention in stages, the upper limit value or the lower limit value recited in one numerical range may be replaced with the upper limit value or the lower limit value recited in another numerical range in stages. In the numerical ranges of the present invention, the upper limit or the lower limit of the numerical range may be replaced with the values shown in the examples.

Further, in the present invention, in the case where a plurality of substances corresponding to each component are present in the composition, the amount of each component in the composition means the total amount of the plurality of substances present in the composition unless otherwise specified.

Also, in the expression of a group (atomic group) in the present specification, the expression not labeled with substituted and unsubstituted includes a group having no substituent and also includes a group having a substituent. For example, "alkyl group" includes not only an alkyl group having no substituent (unsubstituted alkyl group) but also an alkyl group having a substituent (substituted alkyl group).

In the present specification, "(meth) acrylic acid" is a term used as a concept including both acrylic acid and methacrylic acid, and "(meth) acryloyl group" is a term used as a concept including both acryloyl group and methacryloyl group.

Also, in the present invention, in the case where a label regarding a group in a compound represented by formula (la), when it is not labeled with a substituted or unsubstituted group, the group may further have a substituent, unless otherwise specified, the group includes not only an unsubstituted group but also a group having a substituent. For example, in the formula, provided that there is "R ^X When the term "represents an alkyl group, an aryl group or a heterocyclic group", it means "R ^X Represents unsubstituted alkyl, substituted alkyl, unsubstituted aryl, substituted aryl, unsubstituted heterocyclic group or substituted heterocyclic group ".

The term "step" in the present specification includes not only an independent step but also a step that can achieve the intended purpose of the step even when the step cannot be clearly distinguished from other steps. In the present invention, "mass%" means the same as "weight%" and "parts by mass" means the same as "parts by weight".

In the present invention, each component in the composition or each structural unit in the polymer may contain one kind or two or more kinds of the components or the structural units may be used simultaneously unless otherwise specified.

Further, in the present invention, in the case where a plurality of substances or structural units corresponding to each constituent in the composition or each structural unit in the polymer are present, unless otherwise specified, the amount of each structural unit in each constituent or polymer in the composition means the total amount of the corresponding plurality of substances present in the composition or the corresponding plurality of each structural units present in the polymer.

In the present invention, a combination of two or more preferred embodiments is a more preferred embodiment.

Also, unless otherwise specified, the weight average molecular weight (Mw) and the number average molecular weight (Mn) in the present invention are molecular weights obtained by detection with a solvent THF (tetrahydrofuran), a differential refractometer and conversion using polystyrene as a standard substance by a Gel Permeation Chromatography (GPC) analyzer of a column using TSKgel GMHxL, TSKgel G4000HxL, TSKgel G2000HxL (both product names manufactured by TOSOH CORPORATION).

In the present invention, the term "lithographic printing plate precursor" includes not only lithographic printing plate precursors but also waste printing plate precursors. The term "lithographic printing plate" includes not only a lithographic printing plate produced by exposing and developing a lithographic printing plate precursor as needed, but also a waste plate. In the case of a waste plate precursor, the operations of exposure and development are not necessarily required. The waste plate is a lithographic printing plate precursor to be mounted on an unused plate cylinder when printing is performed on a part of a paper surface in a single color or two colors in, for example, color newspaper printing.

In the present invention, an "" in the chemical structural formula represents a bonding position with another structure.

The present invention will be described in detail below.

(original plate of lithographic printing plate)

The lithographic printing plate precursor according to the present invention has an image recording layer on a support, and the image recording layer contains an infrared absorber represented by the following formula 1-1 (hereinafter, also referred to as "specific infrared absorber"), a polymerization initiator, and a polymerizable compound.

The lithographic printing plate precursor according to the present invention is preferably an on-press developable lithographic printing plate precursor.

[ chemical formula 9]

In the formula 1-1, R ¹ Represents a group represented by formula 2, R ₁₁ ～R ₁₈ Each independently represents a hydrogen atom, a halogen atom, -R ^a 、-OR ^b 、-SR ^c or-NR ^d R ^e ，R ^a ～R ^e Each independently represents a hydrocarbon group, A ₁ 、A ₂ And a plurality of R ₁₁ ～R ₁₈ May be linked to form a monocyclic or polycyclic ring, A ₁ And A ₂ Each independently represents an oxygen atom, a sulfur atom or a nitrogen atom, n ₁₁ And n ₁₂ Each independently represents an integer of 0 to 5, wherein n ₁₁ And n ₁₂ Is 2 or more, n ₁₃ And n ₁₄ Each independently represents 0 or 1,L represents an oxygen atom, a sulfur atom or-NR ¹⁰ -，R ¹⁰ Represents a hydrogen atom, an alkyl group or an aryl group, and Za represents a counter ion for neutralizing a charge.

[ chemical formula 10]

In formula 2, R ^Z Represents an alkyl group, and the wavy line represents a bonding site with a group represented by L in the above formula 1-1.

As a result of intensive studies, the present inventors have found that a lithographic printing plate precursor capable of providing a lithographic printing plate having excellent brushing resistance (hereinafter, also referred to as "UV brushing resistance") even when a UV ink (hereinafter, also referred to as "ultraviolet curable ink") is used can be obtained by adopting the above-described structure.

The detailed mechanism by which the above-described effects can be obtained is not clear, but is presumed as follows.

The lithographic printing plate precursor according to the present invention contains an infrared absorber having a specific structure in the image recording layer, and it is considered that the infrared absorber having a specific structure is easily decomposed due to having a specific structure. It is also assumed that the lithographic printing plate precursor according to the present invention uses an infrared absorber having a specific structure, a polymerization initiator, and a polymerizable compound in combination in the image recording layer, and that the infrared absorber or its decomposition product promotes polymerization at the time of polymerization of the polymerizable compound to improve polymerization efficiency and obtain a film having high polarity, and therefore, the lithographic printing plate precursor is excellent in brushing resistance (UV brushing resistance) even when a UV ink is used.

Further, the infrared absorber having a specific structure contained in the image recording layer is more excellent in color developability and is less likely to undergo color fading with time, and therefore the lithographic printing plate precursor of the present invention is more likely to obtain excellent color developability with time.

Hereinafter, the details of each constituent element of the lithographic printing plate precursor according to the present invention will be described.

< support >

The lithographic printing plate precursor of the present invention has a support.

As the support, a support having a hydrophilic surface (also referred to as "hydrophilic support") is preferable. As the hydrophilic surface, a contact angle with water is preferably less than 10 °, more preferably less than 5 °.

The water contact angle in the present invention was measured as a contact angle of a water droplet on a surface at 25 ℃ (after 0.2 sec) by DM-501 manufactured by Kyowa Interface Science co.

The support for the lithographic printing plate precursor according to the present invention can be appropriately selected from known supports for lithographic printing plate precursors and used. The support is preferably an aluminum plate which has been subjected to surface roughening treatment and anodic oxidation treatment by a known method.

The aluminum plate can be further subjected to a treatment for enlarging and sealing micropores of the anodic oxide film as described in japanese patent laid-open nos. 2001-253181 and 2001-322365, a surface hydrophilization treatment based on an alkali metal silicate as described in each specification of U.S. Pat. No. 2,714,066, U.S. Pat. No.3,181,461, U.S. Pat. No.3,280,734, and U.S. Pat. No.3,902,734, and a surface hydrophilization treatment based on polyvinyl phosphonic acid or the like as described in each specification of U.S. Pat. No.3,276,868, U.S. Pat. No. 4,153,461, and U.S. Pat. No. 4,689,272, as needed, as appropriate.

The center line average roughness of the support is preferably 0.10 to 1.2 μm.

The support may have a back coat layer containing an organic polymer compound described in Japanese patent application laid-open No. 5-045885 or a silicon alkoxide compound described in Japanese patent application laid-open No. 6-035174 on the surface opposite to the image recording layer, if necessary.

[ preferred embodiment of support ]

An example of a preferable embodiment of the aluminum support used in the present invention (hereinafter, the aluminum support according to an embodiment of the present invention is also referred to as "support (1)") is shown below.

That is, the support (1) has an aluminum plate and an anodized aluminum film disposed on the aluminum plate, the anodized aluminum film is positioned closer to the image recording layer side than the aluminum plate, the anodized aluminum film has micropores extending in the depth direction from the surface on the image recording layer side, the average diameter of the micropores on the surface of the anodized aluminum film exceeds 10nm and is 100nm or less, and preferably the L of the surface of the anodized aluminum film on the image recording layer side is L ^* a ^* b ^* Lightness L in the color system ^* The value of (A) is 70 to 100.

Fig. 1 is a schematic cross-sectional view of an embodiment of aluminum support body 12 a.

The aluminum support 12a has a laminated structure in which an aluminum plate 18 and an aluminum anodic oxide film 20a (hereinafter, also simply referred to as "anodic oxide film 20 a") are laminated in this order. Further, the anodized film 20a in the aluminum support 12a is positioned on the image recording layer side of the aluminum plate 18. That is, the lithographic printing plate precursor according to the present invention preferably has at least an anodic oxide film, an image recording layer, and a water-soluble resin layer in this order on an aluminum plate.

Anodic oxidation coating film-

Hereinafter, a preferred embodiment of the anodic oxidation coating film 20a will be described.

The anodic oxide coating 20a is a coating formed on the surface of the aluminum plate 18 by anodic oxidation treatment, and has fine micropores 22a that are substantially perpendicular to the surface of the coating and are each uniformly distributed. The micropores 22a extend in the thickness direction (aluminum plate 18 side) from the surface of the anodic oxide film 20a on the image recording layer side (the surface of the anodic oxide film 20a on the side opposite to the aluminum plate 18 side).

The average diameter (average opening diameter) on the surface of the anodic oxide film of the micropores 22a in the anodic oxide film 20a is preferably more than 10nm and 100nm or less. Among them, from the viewpoint of the balance among the brushing resistance, the stain resistance and the image visibility, it is more preferably 15nm to 60nm, still more preferably 20nm to 50nm, and particularly preferably 25nm to 40nm. The diameter of the interior of the pores may be wider or narrower than the skin.

When the average diameter exceeds 10nm, the brush resistance and the image visibility are more excellent. Further, when the average diameter is 100nm or less, the brush resistance is more excellent.

The average diameter of the micropores 22a was calculated as an arithmetic average value by measuring the diameter (diameter) of 50 micropores existing in a range of 400nm × 600nm in 4 images obtained by observing the surface of N =4 anodized films 20a with a field emission scanning electron microscope (FE-SEM) having a magnification of 15 ten thousand times.

In addition, in the case where the shape of the minute hole 22a is not a circle, a circle-equivalent diameter is used. The "circle-equivalent diameter" is a diameter of a circle when the shape of the opening is assumed to be a circle having the same projected area as the projected area of the opening.

The depth of the micropores 22a is not particularly limited, but is preferably 10nm to 3000nm, more preferably 50nm to 2000nm, and still more preferably 300nm to 1600nm.

The depth is a value obtained by taking a photograph (15 ten thousand times) of a cross section of the anodic oxide film 20a, measuring the depth of 25 or more micropores 22a, and averaging the measured depths.

The shape of the micropores 22a is not particularly limited, and is a substantially straight tubular shape (substantially cylindrical shape) in fig. 2, but may be a conical shape whose diameter becomes smaller in the depth direction (thickness direction). The shape of the bottom of the micropore 22a is not particularly limited, and may be a curved surface (convex) or a flat surface.

In the support (1), the following are also preferable: and the micropores are composed of large-diameter holes extending from the surface of the anodized film to a depth of 10nm to 1,000nm and small-diameter holes communicating with the bottoms of the large-diameter holes and extending from the communication positions to a depth of 20nm to 2,000nm, wherein the average diameter of the large-diameter holes on the surface of the anodized film is 15nm to 150nm, and the average diameter of the small-diameter holes at the communication positions is 13nm or less (hereinafter, the support according to the above-described embodiment is also referred to as "support (2)").

Fig. 2 is a schematic cross-sectional view of an embodiment of aluminum support body 12a different from aluminum support body 12a shown in fig. 1. Support B is an embodiment of aluminum support 12a shown in fig. 2.

In fig. 2, the aluminum support 12b includes an aluminum plate 18 and an anodic oxide film 20b having micropores 22b composed of large-diameter holes 24 and small-diameter holes 26.

The micropores 22b in the anodized film 20b are constituted by large-diameter pores 24 extending from the surface of the anodized film to a depth of 10nm to 1000nm (depth D: refer to FIG. 2), and small-diameter pores 26 communicating with the bottoms of the large-diameter pores 24 and further extending from the communicating positions to a depth of 20nm to 2000nm.

The large-diameter hole 24 and the small-diameter hole 26 will be described in detail below.

The average diameter on the surface of the anodized film 20b of the large-diameter pores 24 is equal to or larger than 10nm and equal to or smaller than 100nm, preferably in the same range as the average diameter on the surface of the anodized film of the micropores 22a in the anodized film 20 a.

The method of measuring the average diameter on the surface of the anodic oxide film 20b of the large-diameter pores 24 is the same as the method of measuring the average diameter on the surface of the anodic oxide film of the micropores 22a in the anodic oxide film 20 a.

The bottom of the large-diameter hole 24 is located at a depth of 10nm to 1,000nm (hereinafter, also referred to as depth D) from the surface of the anodized film. That is, the large-diameter holes 24 are holes extending from the surface of the anodized film to a position of 10nm to 1,000nm in the depth direction (thickness direction). The depth is preferably 10nm to 200nm.

The depth is a value obtained by taking a photograph (15 ten thousand times) of a cross section of the anodized film 20b, measuring the depths of 25 or more large-diameter holes 24, and averaging the measured depths.

The shape of the large-diameter hole portion 24 is not particularly limited, and examples thereof include a substantially straight tube shape (substantially cylindrical shape) and a conical shape having a diameter decreasing in the depth direction (thickness direction), and the shape is preferably a substantially straight tube shape.

As shown in fig. 2, the small-diameter hole portion 26 is a hole portion that communicates with the bottom of the large-diameter hole portion 24 and extends further in the depth direction (thickness direction) from the communication position.

The average diameter of the small-diameter pores 26 at the communication position is preferably 13nm or less. Among them, it is preferably 11nm or less, and more preferably 10nm or less. The lower limit is not particularly limited, but is usually 5nm or more.

The average diameter of the small-diameter pores 26 was obtained as an arithmetic average value by observing the surface of N =4 anodized films 20a with an FE-SEM having a magnification of 15 ten thousand times, and measuring the diameter (diameter) of micropores (small-diameter pores) existing in a range of 400nm × 600nm in the obtained 4 images. When the large-diameter hole has a deep depth, the average diameter of the small-diameter holes can be determined by cutting (e.g., cutting with argon gas) the upper portion (a certain region of the large-diameter hole) of the anodized film 20b as needed, and observing the surface of the anodized film 20b with the FE-SEM.

When the small-diameter hole 26 is not circular, a circle-equivalent diameter is used. The "circle-equivalent diameter" is a diameter of a circle when the shape of the opening is assumed to be a circle having a projection area equal to the projection area of the opening.

The bottom of the small-diameter hole 26 is located at a position extending 20nm to 2000nm in the depth direction from the position communicating with the large-diameter hole 24. In other words, the small-diameter holes 26 are holes extending further in the depth direction (thickness direction) from the positions communicating with the large-diameter holes 24, and the depth of the small-diameter holes 26 is 20nm to 2000nm. The depth is preferably 500nm to 1500nm.

The depth is a value obtained by taking a photograph (5 ten thousand times) of a cross section of the anodized film 20b, measuring the depths of 25 or more small-diameter holes, and averaging the measured depths.

The shape of the small-diameter hole 26 is not particularly limited, and examples thereof include a substantially straight tube shape (substantially cylindrical shape) and a conical shape whose diameter decreases in the depth direction, and the shape is preferably a substantially straight tube shape.

< image recording layer >

The lithographic printing plate precursor according to the present invention has an image recording layer formed on a support.

The image recording layer used in the present invention contains a specific infrared absorber, a polymerization initiator, and a polymerizable compound.

The image recording layer used in the present invention may further contain an acid developer in order to confirm exposed portions before development.

From the viewpoint of on-press developability, the lithographic printing plate precursor according to the present invention is preferably capable of removing unexposed portions of the image recording layer by at least one selected from the group consisting of a fountain solution and a printing ink.

The details of each component contained in the image recording layer will be described below.

[ specific Infrared absorbers ]

The image recording layer contains an infrared absorber (specific infrared absorber) represented by formula 1-1.

It is considered that the infrared absorbent having a specific structure is easily decomposed because of having a specific structure, and the infrared absorbent or its decomposition product promotes polymerization when the polymerizable compound is polymerized. Therefore, the lithographic printing plate precursor according to the present invention has excellent UV resistance because the polymerization efficiency is further improved and a film having high polarity can be obtained by using an infrared absorber having a specific structure, a polymerization initiator, and a polymerizable compound in combination in the image recording layer.

The specific infrared absorber preferably has a property of decomposing by heat or infrared exposure to generate a color body with high visibility.

In the present invention, "color development" means that there is almost no absorption in the visible light region (400 or more and less than 750 nm) before heating or infrared exposure, and that there is strong coloration or absorption of short wavelength and absorption in the visible light region after heating or infrared exposure.

That is, the specific infrared absorber of the present invention is a compound which decomposes by heat or infrared exposure, increases the absorption in the visible light region compared to before heating or infrared exposure, or has a shorter absorption wavelength and has absorption in the visible light region.

The specific infrared absorber may be a specific infrared absorber that absorbs and decomposes at least a part of light in an infrared wavelength region (wavelength of 750nm to 1mm, preferably 750nm to 1,400nm), and is preferably an infrared absorber having a maximum absorption in a wavelength region of 750nm to 1,400nm.

The specific infrared absorber is preferably a compound that generates a compound that decomposes by thermal or infrared exposure to have an absorption maximum wavelength in the range of 500nm to 600nm.

The specific infrared absorber is preferably an infrared absorbing dye that decomposes by electron movement due to infrared exposure. Here, "decomposition by electron transfer" means that, by exposure to infrared light, an electron excited from a HOMO (highest occupied orbital) to a LUMO (lowest unoccupied molecular orbital) of a specific infrared absorber undergoes intramolecular electron transfer to an electron-accepting group (group having a potential close to the LUMO) in a molecule, thereby causing decomposition.

The details of the color-developing mechanism of the specific infrared absorber are not clear, but it is considered that the color-developing mechanism of the specific infrared absorber is exposed to heat or infrared light to thereby cause R in formula 1-1 ¹ -L bond R in formula 2 ^Z -O bond cleavage, L in formula 1-1 being = O, = S or NR ₁₀ Thereby generating a color body. And, it is considered that the compound represented by the formula 1-1 is formed by R ¹ I.e. R in formula 2 ^Z The release contributes to the polymerizable compound contained in the image recording layer, thereby improving the polymerization efficiency.

The present inventors concluded that color is developed by changing the electron structure in an electron conjugated system of the parent structure of a specific infrared absorber.

[ chemical formula 11]

In the formula 1-1, R is preferred ₁₁ ～R ₁₈ Each independently is a hydrogen atom, -R ^a 、-OR ^b 、-SR ^c or-NR ^d R ^e 。

R ^a ～R ^e The hydrocarbon group in (3) is preferably a hydrocarbon group having 1 to 30 carbon atoms, more preferably a hydrocarbon group having 1 to 15 carbon atoms, and still more preferably a hydrocarbon group having 1 to 10 carbon atoms. The hydrocarbon group may be linear, branched, or cyclic.

R in the formula 1-1 is preferable ₁₁ ～R ₁₄ Each independently is a hydrogen atom or an alkyl group, more preferably a hydrogen atom.

And R bonded to the carbon atom bonded to L ₁₁ And R ₁₃ Preferably an alkyl group, more preferably the two are linked to form a ring. The ring formed as described above is preferably a 5-or 6-membered ring, and more preferably a 5-membered ring.

Preferably with A ₁ ⁺ R bound to the carbon atom to which it is bound ₁₂ And A ₂ R bound to the carbon atom to which it is bound ₁₄ Are each independently of R ₁₅ And R ₁₇ Joined to form a ring.

R in the formula 1-1 ₁₅ Preferably a hydrocarbon group. And, preferably R ₁₅ And A ₁ ⁺ R bound to the carbon atom to which it is bound ₁₂ Joined to form a ring. The ring to be formed is preferably an indole ring, a pyrylium ring, a Thiopyrylium (Thiopyrylium) ring, a benzoxazoline ring or a benzimidazoline ring, and more preferably an indole ring from the viewpoint of color developability.

R in the formula 1-1 ₁₇ Preferably a hydrocarbon group. And, preferably R ₁₇ And A ₂ R bound to the carbon atom to which it is bound ₁₄ Joined to form a ring. The ring to be formed is preferably an indole ring, a pyran ring, a thiopyran ring, a benzoxazole ring or a benzimidazole ring, and more preferably an indole ring from the viewpoint of color developability.

R in the formula 1-1 ₁₅ And R ₁₇ The same groups are preferred, and in the case of forming separate rings, the same rings are preferably formed.

R in the formula 1-1 ₁₆ And R ₁₈ Preferably the same groups.

Furthermore, R is preferably R from the viewpoint of improving the water solubility of the compound represented by the formula 1-1 ₁₆ And R ₁₈ Each independently is an alkyl group having a (poly) oxyalkylene group or an alkyl group having an anionic structure, more preferably an alkoxyalkyl group, an alkyl group having a carboxylate group or a sulfonate group, and still more preferably an alkyl group having a sulfonate group at a terminal. The alkyl group is preferably an alkyl group having 1 to 10 carbon atoms, and more preferably an alkyl group having 1 to 4 carbon atoms.

The counter cation of the above anionic structure may be R in the formula 1-1 ¹ A cation which can be contained in L or A ₁ ⁺ The cation may be an alkali metal cation or an alkaline earth metal cation.

The counter cation of the above sulfonate group may be R in the formula 1-1 ¹ A cation which can be contained in L or A ₁ ⁺ It may also be an alkali metal cation and a baseA soil-like metal cation.

Furthermore, the maximum absorption wavelength of the compound represented by the formula 1-1 (specific infrared absorber) is made longer, and R is preferably R from the viewpoint of color developability and UV resistance in a lithographic printing plate ₁₆ And R ₁₈ Each independently is an alkyl group or an alkyl group having an aromatic ring. The alkyl group is preferably an alkyl group having 1 to 10 carbon atoms, more preferably an alkyl group having 1 to 4 carbon atoms, and still more preferably a methyl group or an ethyl group. The alkyl group having an aromatic ring is preferably an alkyl group having an aromatic ring at the end, and more preferably a 2-phenylethyl group, a 2-naphthylethyl group or a 2- (9-anthryl) ethyl group.

N in the formula 1-1 ₁₁ And n ₁₂ The same integer of 0 to 5 is preferable, an integer of 1 to 3 is more preferable, 1 or 2 is further preferable, and 2 is particularly preferable.

A in formula 1-1 ₁ And A ₂ Each independently represents an oxygen atom, a sulfur atom or a nitrogen atom, preferably a nitrogen atom.

A in formula 1-1 ₁ And A ₂ Preferably the same atom.

Za in formula 1-1 represents a counter ion that neutralizes charge. When the anion species is represented, a sulfonate ion, a carboxylate ion, a tetrafluoroborate ion, a hexafluorophosphate ion, a p-toluenesulfonate ion, a perchlorate ion, a hexafluoroantimonate ion, and the like are exemplified, and a hexafluorophosphate ion is preferable. When the cation species is represented, examples thereof include alkali metal ions, alkaline earth metal ions, ammonium ions, pyridinium ions, sulfonium ions, and the like, and sodium ions, potassium ions, ammonium ions, pyridinium ions, or sulfonium ions are preferable, and sodium ions, potassium ions, or ammonium ions are more preferable.

R ₁₁ ～R ₁₈ And R ¹ L may have an anionic or cationic structure, if R ₁₁ ～R ₁₈ And R ¹ L all being charge-neutral radicals, then Za is a monovalent counter anion, e.g. at R ₁₁ ～R ₁₈ And R ¹ When L has two or more anionic structures, za can be a counter cation.

Further, if the compound represented by the formula 1-1 (specific infrared absorber) has a charge-neutral structure in the entire compound, za does not exist.

For R in formula 1-1 ¹ The group represented by formula 2 will be described in detail later.

The specific infrared absorber is preferably a cyanine dye that is decomposed by infrared exposure from the viewpoints of color developability and UV resistance of the obtained lithographic printing plate.

The cyanine dye decomposed by infrared exposure is more preferably represented by formula 1, and still more preferably represented by formula 1-2, from the viewpoint of color developability and UV resistance of the obtained lithographic printing plate.

[ chemical formula 12]

In the formula 1-2, R ¹ Represents a group represented by formula 2, R ² And R ³ Each independently represents a hydrogen atom or an alkyl group, R ² And R ³ May be linked to each other to form a ring, ar ¹ And Ar ² Each independently represents a group forming a benzene ring or a naphthalene ring, Y ¹ And Y ² Each independently represents an oxygen atom, a sulfur atom, -NR ⁰ Or a dialkylmethylene group, R ⁰ Represents a hydrogen atom, an alkyl group or an aryl group, R ⁴ And R ⁵ Each independently represents an alkyl group, -CO ₂ M radical or-PO ₃ M ₂ M represents a hydrogen atom, a sodium atom, a potassium atom or an onium group, R ⁶ ～R ⁹ Each independently represents a hydrogen atom or an alkyl group, L represents an oxygen atom, a sulfur atom or-NR ¹⁰ -，R ¹⁰ Represents a hydrogen atom, an alkyl group or an aryl group, and Za represents a counter ion for neutralizing a charge.

In the formula 1-2, R ² ～R ⁹ And R ⁰ The alkyl group in (1) is preferably an alkyl group having 1 to 30 carbon atoms, more preferably an alkyl group having 1 to 15 carbon atoms, and still more preferably a carbon atomAlkyl groups having a sub-number of 1 to 10. The alkyl group may be linear, branched, or cyclic.

Specific examples thereof include methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, hexadecyl, octadecyl, eicosyl, isopropyl, isobutyl, sec-butyl, tert-butyl, isopentyl, neopentyl, 1-methylbutyl, isohexyl, 2-ethylhexyl, 2-methylhexyl, cyclohexyl, cyclopentyl and 2-norbornyl groups.

Among the alkyl groups, methyl, ethyl, propyl or butyl are preferred.

The above alkyl group may have a substituent. Examples of the substituent include an alkoxy group, an aryloxy group, an amino group, an alkylthio group, an arylthio group, a halogen atom, a carboxyl group, a carboxylate group, a sulfo group, a sulfonate group, an alkoxycarbonyl group, an aryloxycarbonyl group, and a group obtained by combining these groups.

R ⁰ The aryl group in (4) is preferably an aryl group having 6 to 30 carbon atoms, more preferably an aryl group having 6 to 20 carbon atoms, and still more preferably an aryl group having 6 to 12 carbon atoms.

The above aryl group may have a substituent. Examples of the substituent include an alkyl group, an alkoxy group, an aryloxy group, an amino group, an alkylthio group, an arylthio group, a halogen atom, a carboxyl group, a carboxylate group, a sulfo group, a sulfonate group, an alkoxycarbonyl group, an aryloxycarbonyl group, and a group obtained by combining these groups.

Specific examples thereof include phenyl, naphthyl, p-tolyl, p-chlorophenyl, p-fluorophenyl, p-methoxyphenyl, p-dimethylaminophenyl, p-methylthiophenyl and p-phenylthiophenyl.

Among the aryl groups, phenyl, p-methoxyphenyl, p-dimethylaminophenyl or naphthyl are preferred.

R ² And R ³ Preferably joined to form a ring.

At R ² And R ³ When they are linked to form a ring, they are preferably 5-or 6-membered rings, and particularly preferably 5-membered rings.

Y ¹ And Y ² Each independently represents an oxygen atom, a sulfur atom, -NR ⁰ -or dialkylmethylene, preferably-NR ⁰ -or a dialkylmethylene group, more preferably a dialkylmethylene group.

R ⁰ Represents a hydrogen atom, an alkyl group or an aryl group, preferably an alkyl group.

R ⁴ Or R ⁵ The alkyl groups represented may be substituted alkyl groups. As R ⁴ Or R ⁵ Examples of the substituted alkyl group include those represented by any of the following formulae (a 1) to (a 4).

[ chemical formula 13]

-R ^W2 -CO ₂ M (a2)

-R ^W3 -PO ₃ M ₂ (a3)

-R ^W4 -SO ₃ M (a4)

In the formulae (a 1) to (a 4), R ^W0 Represents an alkylene group having 2 to 6 carbon atoms, W represents a single bond or an oxygen atom, n _W1 Represents an integer of 1 to 45, R ^W1 Represents an alkyl group having 1 to 12 carbon atoms or-C (= O) -R ^W5 ，R ^W5 Represents an alkyl group having 1 to 12 carbon atoms, R ^W2 ～R ^W4 Each independently represents a single bond or an alkylene group having 1 to 12 carbon atoms, and M represents a hydrogen atom, a sodium atom, a potassium atom or an onium group.

In the formula (a 1), as R ^W0 Specific examples of the alkylene group include a vinyl group, a n-propylene group, an isopropylene group, a n-butylene group, an isobutylene group, a n-pentylene group, an isopentylene group, a n-hexylene group, and an isohexylene group, and preferably a vinyl group, a n-propylene group, an isopropylene group, and a n-butylene group, and particularly preferably a n-propylene group.

n _W1 Preferably 1 to 10, more preferably 1 to 5, and particularly preferably 1 to 3.

As R ^W1 Specific examples of the alkyl group include methyl, ethyl, n-propyl and isopropylN-butyl, isobutyl, tert-butyl, n-pentyl, isopentyl, neopentyl, n-hexyl, n-octyl, and n-dodecyl, etc., preferably methyl, ethyl, n-propyl, isopropyl, n-butyl, and tert-butyl, more preferably methyl and ethyl, and particularly preferably methyl.

R ^W5 Alkyl group represented by the formula and R ^W1 The alkyl radicals represented are identical, preferably also in a manner similar to R ^W1 The preferred modes of the alkyl groups represented are the same.

Specific examples of the group represented by the formula (a 1) are shown below, but the present invention is not limited thereto. In the following structural formulae, me represents a methyl group, et represents an ethyl group, and x represents a bonding site.

[ chemical formula 14]

In the formulae (a 2) to (a 4), R is ^W2 ～R ^W4 Specific examples of the alkylene group include a methylene group, a vinyl group, a n-propylene group, an isopropylene group, a n-butylene group, an isobutylene group, a n-pentylene group, an isopentylene group, a n-hexylene group, an isohexylene group, a n-octylene group, and a n-dodecylene group, and preferably include a vinyl group, a n-propylene group, an isopropylene group, and a n-butylene group, and particularly preferably include a vinyl group and a n-propylene group.

In the formula (a 3), M in two groups may be the same or different.

In the formulae (a 2) to (a 4), examples of the onium group represented by M include an ammonium group, an iodonium group, a phosphonium group, and a sulfonium group.

Among the groups represented by the formulae (a 1) to (a 4), R is R from the viewpoint of color developability and UV resistance of the lithographic printing plate obtained ⁴ Or R ⁵ The substituted alkyl group represented by the formula (a 1) is preferably a group (-R) represented by the formula (a 1) or the formula (a 4) ^w4 SO ₃ M group), more preferably a group represented by formula (a 4).

In the formula 1-2, R is preferred ⁴ And R ⁵ Each is unsubstituted alkyl. R ⁴ And R ⁵ Preferably, it isThe same groups.

R ⁶ ～R ⁹ Each independently represents a hydrogen atom or an alkyl group, preferably a hydrogen atom.

Ar ¹ And Ar ² Each independently represents a group forming a benzene ring or a naphthalene ring. The benzene ring and the naphthalene ring may have a substituent. Examples of the substituent include an alkyl group, an alkoxy group, an aryloxy group, an amino group, an alkylthio group, an arylthio group, a halogen atom, a carboxyl group, a carboxylate group, a sulfo group, a sulfonate group, an alkoxycarbonyl group, an aryloxycarbonyl group, an acyloxy group, a phosphonate group, and a group obtained by combining these groups. The substituent is preferably an alkyl group.

Further, in order to make the maximum absorption wavelength of the cyanine dye represented by formula 1-2 longer, and to improve color developability and UV resistance of a lithographic printing plate, ar is preferable ¹ And Ar ² Each independently is a group forming a naphthalene ring or a benzene ring having an alkyl group or an alkoxy group as a substituent, more preferably a group forming a naphthalene ring or a benzene ring having an alkoxy group as a substituent, and particularly preferably a group forming a naphthalene ring or a benzene ring having a methoxy group as a substituent.

In the formula 1-2, ar is preferably Ar ¹ Or Ar ² A group which forms a group represented by the following formula (b 1).

[ chemical formula 15]

In the formula (b 1), R ¹⁹ Represents an alkyl group having 1 to 12 carbon atoms. n3 represents an integer of 1 to 4. * Indicating the bonding site.

Za represents a counter ion for neutralizing charge. Among them, the cyanine dye represented by formula 1-2 has an ionic substituent corresponding to the structure, and when neutralization of charges is not required, za is not required. When Za represents an anionic species, examples thereof include a sulfonate ion, a carboxylate ion, a tetrafluoroborate ion, a hexafluorophosphate ion, a p-toluenesulfonate ion, a perchlorate ion, a hexafluoroantimonate ion and the like, and a hexafluorophosphate ion is preferable. When Za represents a cationic species, examples thereof include an alkali metal ion, an alkaline earth metal ion, an ammonium ion, a pyridinium ion, a sulfonium ion, and the like, preferably a sodium ion, a potassium ion, an ammonium ion, a pyridinium ion, or a sulfonium ion, and more preferably a sodium ion, a potassium ion, or an ammonium ion.

R ¹ ～R ⁹ 、R ⁰ 、Ar ¹ 、Ar ² 、Y ¹ And Y ² Can have an anionic structure and a cationic structure, if R ¹ ～R ⁹ 、R ⁰ 、Ar ¹ 、Ar ² 、Y ¹ And Y ² All being charge-neutral radicals, then Za is a monovalent counter anion, e.g. at R ¹ ～R ⁹ 、R ⁰ 、Ar ¹ 、Ar ² 、Y ¹ And Y ² When the cation has two or more anionic structures, za can be a counter cation.

-R ¹ A group represented by the formula 2

For R in the above formulae 1-1 and 1-2 ¹ The group represented by the above formula 2 will be described later.

R ¹ The group represented by the above formula 2 is preferably R in the formula 2 by exposure to heat or infrared light ^Z -an O bond breaking group.

[ chemical formula 16]

In formula 2, R ^Z Represents an alkyl group, and the wavy line represents a bonding site to a group represented by L in the formula 1-1 or the formula 1-2. As R ^Z Alkyl group represented by the formula, with the above R ² ～R ⁹ And R ⁰ The preferable mode of the alkyl group in (1) is the same.

From the viewpoint of color developability and UV resistance of the lithographic printing plate obtained, the alkyl group is preferably a secondary alkyl group or a tertiary alkyl group, and is preferably a tertiary alkyl group.

In view of color developability and UV resistance of the lithographic printing plate obtained, the alkyl group is preferably an alkyl group having 1 to 8 carbon atoms, more preferably a branched alkyl group having 3 to 10 carbon atoms, still more preferably a branched alkyl group having 3 to 6 carbon atoms, and particularly preferably an isopropyl group or a tert-butyl group, and most preferably a tert-butyl group.

L in the formula 1-1 or the formula 1-2 is preferably an oxygen atom from the viewpoint of UV brush resistance.

The following are mentioned for R in the formula 1-1 or formula 1-2 ¹ Specific examples of the groups are shown, but the present invention is not limited thereto.

In the following structural formula, ● represents a bonding site to L in formula 1-1 or formula 1-2.

[ chemical formula 17]

In the formula 1-1 or the formula 1-2, in the case where L is an oxygen atom, when R in the formula 2 ^Z Aryl or linear alkyl, does not cause R upon infrared exposure ^Z -cleavage of the O bond.

In the formula 1-1 or the formula 1-2, L preferably represents a sulfur atom or-NR from the viewpoint of improving UV brush resistance ¹⁰ -，R ¹⁰ Represents a hydrogen atom, an alkyl group or an aryl group.

Specific examples of the compound represented by the formula 1-1 or the formula 1-2 are shown below, but the present invention is not limited thereto. In the following structural formula, me represents a methyl group, tsO ^- Represents a p-toluenesulfonate anion.

[ chemical formula 18]

[ chemical formula 19]

[ chemical formula 20]

[ chemical formula 21]

[ chemical formula 22]

[ chemical formula 23]

[ chemical formula 24]

[ chemical formula 25]

The compound represented by formula 1-1 or formula 1-2 can be synthesized by applying a known method.

The compound represented by the formula 1-1 is a compound wherein L is-NR in the formula 1-1 ¹⁰ -and R bonded to N ¹ In the case of the compound having a group represented by the above formula 2, a method according to the following scheme 2 can be preferably used.

In scheme 2 below, the various symbols are the same as those in formulas 1-1, 1-2 and 2.

[ chemical formula 26]

(scheme 2)

Further, for example, the compound represented by the formula 1-1 can be preferably a method of introducing the group represented by the formula 2 by a synthesis scheme represented by the following formula (S1).

In the following formulae, DMAP represents N, N-dimethylamino-4-pyridine, acONa represents sodium acetate, and Me represents methyl. And, R ^Z Represents a group corresponding to each moiety in formula 2.

[ chemical formula 27]

One specific infrared absorber may be used alone, or two or more of them may be used simultaneously.

The content of the specific infrared absorber in the image recording layer is preferably 0.1 to 95% by mass, more preferably 1 to 50% by mass, and still more preferably 1 to 40% by mass, based on the total mass of the image recording layer.

The specific infrared absorber itself has excellent infrared absorption performance, and therefore, functions well as an infrared absorber. Accordingly, when the specific infrared absorber is used for the image recording layer of the lithographic printing plate precursor, it is not actually necessary to use an infrared absorber other than the specific infrared absorber (hereinafter, also referred to as "other infrared absorber"), but the image recording layer may contain another infrared absorber.

[ other Infrared absorbers ]

The above-mentioned image recording layer may contain an infrared absorbing agent other than the specific infrared absorbing agent.

Examples of the other infrared absorbers include pigments and dyes.

As The dye used as another infrared absorber, there can be used a commercially available dye and a known dye described in The literature such as "dye overview" (The Society of Synthetic Organic Chemistry, japan.ed., 1970). Specific examples thereof include azo dyes, metal complex azo dyes, pyrazolone azo dyes, naphthoquinone dyes, anthraquinone dyes, phthalocyanine dyes, carbonium dyes, quinonimine dyes, methine dyes, cyanine dyes, squarylium pigments, pyrylium salts, metal thiolate complexes, and the like.

Among these dyes, particularly preferable dyes include cyanine dyes, squarylium dyes, pyrylium salts, nickel thiol complexes, and indocyanine dyes. Further, cyanine dyes and indocyanine dyes can be mentioned. Among them, cyanine is particularly preferable.

Specific examples of the cyanine dye include compounds described in paragraphs 0017 to 0019 of Japanese patent application laid-open No. 2001-133969, paragraphs 0016 to 0021 of Japanese patent application laid-open No. 2002-023360, and paragraphs 0012 to 0037 of Japanese patent application laid-open No. 2002-040638, and preferably include compounds described in paragraphs 0034 to 0041 of Japanese patent application laid-open No. 2002-278057 and paragraphs 0080 to 0086 of Japanese patent application laid-open No. 2008-195018, and particularly preferably include compounds described in paragraphs 0035 to 0043 of Japanese patent application laid-open No. 2007-090850, and compounds described in paragraphs 0105 to 0113 of Japanese patent application laid-open No. 2012-206495.

Further, compounds described in paragraphs 0008 to 0009 of Japanese patent application laid-open No. 5-005005 and paragraphs 0022 to 0025 of Japanese patent application laid-open No. 2001-222101 can also be preferably used.

The pigment is preferably a compound described in paragraphs 0072 to 0076 of jp 2008-195018 a.

The other infrared absorbers may be used alone or in combination of two or more. Further, as the infrared absorber, a pigment and a dye may be used together.

The content of the other infrared absorber in the image recording layer is preferably less than the content of the specific infrared absorber from the viewpoint of color developability and UV resistance of the obtained lithographic printing plate, and the image recording layer preferably does not contain the other infrared absorber.

[ adhesive Polymer ]

The image recording layer used in the present invention preferably further contains a binder polymer, and more preferably contains a binder polymer having a structural unit formed from an aromatic vinyl compound (hereinafter, also referred to as "specific binder polymer").

In the present invention, the binder polymer is a binding resin that is not in the form of particles, and polymer particles described later are not included in the binder polymer in the present invention.

The specific binder polymer preferably further has a structural unit formed of an acrylonitrile compound from the viewpoints of developability, color developability, and UV resistance in the obtained lithographic printing plate.

Structural units formed from aromatic vinyl compounds

The aromatic vinyl compound contained in the specific binder polymer may be a compound having a structure in which a vinyl group is bonded to an aromatic ring, and examples thereof include a styrene compound and a vinylnaphthalene compound, and a styrene compound is preferred, and styrene is more preferred.

The styrene compound includes styrene, p-methylstyrene, p-methoxystyrene, β -methylstyrene, p-methyl- β -methylstyrene, α -methylstyrene and p-methoxy- β -methylstyrene, and styrene is preferably used.

Examples of the vinylnaphthalene compound include 1-vinylnaphthalene, methyl-1-vinylnaphthalene,. Beta. -methyl-1-vinylnaphthalene, 4-methyl-1-vinylnaphthalene, and 4-methoxy-1-vinylnaphthalene, and 1-vinylnaphthalene is preferably used.

Further, as the structural unit formed of an aromatic vinyl compound, a structural unit represented by the following formula A1 can be preferably mentioned.

[ chemical formula 28]

In the formula A1, R ^A1 And R ^A2 Each independently represents a hydrogen atom or an alkyl group, ar represents an aromatic ring group, R ^A3 Represents a substituent, and n represents an integer not more than the maximum number of substituents of Ar.

In the formula A1, R is preferred ^A1 And R ^A2 Each independently represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, more preferably a hydrogen atom or a methyl group, and still more preferably a hydrogen atom.

In formula A1, ar is preferably a benzene ring or a naphthalene ring, more preferably a benzene ring.

In the formula A1, R ^A3 Preferably an alkyl group or an alkoxy group, more preferably an alkyl group having 1 to 4 carbon atoms or an alkoxy group having 1 to 4 carbon atoms, and still more preferably a methyl group or a methoxy group.

In formula A1, in the presence of a plurality of R ^A3 In the case of (2), a plurality of R ^A3 May be the same or different.

In formula A1, n is preferably an integer of 0 to 2, more preferably 0 or 1, and even more preferably 0.

The content of the structural unit formed from an aromatic vinyl compound in the specific binder polymer is preferably 15 to 85 mass%, more preferably 30 to 70 mass%, with respect to the total mass of the specific binder polymer.

Structural units formed from acrylonitrile compounds

The acrylonitrile compound includes (meth) acrylonitrile and the like, and acrylonitrile is preferably used.

Further, as the structural unit formed of an acrylonitrile compound, a structural unit represented by the following formula B1 can be preferably mentioned.

[ chemical formula 29]

In the formula B1, R ^B1 Represents a hydrogen atom or an alkyl group.

In the formula B1, R ^B1 A hydrogen atom or an alkyl group having 1 to 4 carbon atoms is preferable, a hydrogen atom or a methyl group is more preferable, and a hydrogen atom is even more preferable.

The content of the structural unit composed of an acrylonitrile compound in the specific binder polymer is preferably 5 to 85 mass%, more preferably 8 to 70 mass%, with respect to the total mass of the specific binder polymer.

Structural units formed from N-vinyl heterocyclic compounds

From the viewpoint of UV brush resistance and chemical resistance, the specific binder polymer preferably further has a structural unit formed of an N-vinyl heterocyclic compound.

Examples of N-vinyl heterocyclic compounds include N-vinylpyrrolidone, N-vinylcarbazole, N-vinylpyrrole, N-vinylphenothiazine, N-vinylsuccinimide, N-vinylphthalimide, N-vinylcaprolactam and N-vinylimidazole, with N-vinylpyrrolidone being preferred.

Further, as the structural unit formed of the N-vinyl heterocyclic compound, a structural unit represented by the following formula C1 can be preferably mentioned.

[ chemical formula 30]

In the formula C1, ar ^N Represents a heterocyclic structure containing a nitrogen atom, ar ^N The nitrogen atom in (b) is bonded to the carbon atom indicated by x.

In the formula C1, ar ^N The heterocyclic structure represented is preferably a pyrrolidone ring, a carbazole ring, a pyrrole ring, a phenothiazine ring, a succinimide ring, a phthalimide ring, a caprolactam ring, and an imidazole ring, and more preferably a pyrrolidone ring.

And, ar ^N Heterocyclic ring ofThe structure may have a known substituent.

The content of the structural unit formed of the N-vinyl heterocyclic compound in the specific binder polymer is preferably 5 to 70% by mass, and more preferably 10 to 60% by mass, with respect to the total mass of the specific binder polymer.

Structural units having ethylenically unsaturated groups

The particular binder polymer may also comprise structural units having ethylenically unsaturated groups.

The ethylenically unsaturated group is not particularly limited, but examples thereof include a vinyl group, an allyl group, a vinylphenyl group, a (meth) acrylamide group, a (meth) acryloyloxy group, and the like, and from the viewpoint of reactivity, a (meth) acryloyloxy group is preferable.

The structural unit having an ethylenically unsaturated group can be introduced into a specific binder polymer by a high molecular reaction or copolymerization. Specifically, the introduction can be carried out, for example, by a method of reacting a compound having an epoxy group and an ethylenically unsaturated group (e.g., glycidyl methacrylate) with a polymer into which a structural unit having a carboxyl group such as methacrylic acid is introduced, a method of reacting a compound having an isocyanate group and an ethylenically unsaturated group (e.g., 2-isocyanatoethyl methacrylate) with a polymer into which a structural unit having an active hydrogen group such as a hydroxyl group is introduced, or the like.

The structural unit having an ethylenically unsaturated group can be introduced into the specific binder polymer by a method such as reacting a compound having a carboxyl group and an ethylenically unsaturated group with a polymer into which a structural unit having an epoxy group such as glycidyl (meth) acrylate is introduced.

The structural unit having an ethylenically unsaturated group can be introduced into a specific binder polymer by using a monomer containing a partial structure represented by the following formula d1 or d2, for example. Specifically, for example, after polymerization is performed using at least the above-mentioned monomer, a partial structure represented by the following formula d1 or d2 is subjected to a release reaction using a salt-based compound to form an ethylenically unsaturated group, thereby introducing a structural unit having a polymerizable group into a specific binder polymer.

In the formulae d1 and d2, R ^d Represents a hydrogen atom or an alkyl group, A ^d Represents a halogen atom, X ^d represents-O-or-NR ^N -，R ^N Represents a hydrogen atom or an alkyl group, and represents a bonding site with another structure.

In the formulae d1 and d2, R ^d Preferably a hydrogen atom or a methyl group.

In the formulae d1 and d2, A ^d Preferably a chlorine atom, a bromine atom or an iodine atom.

In the formulae d1 and d2, X ^d preferably-O-. At X ^d represents-NR ^N In the case of-R ^N Preferably a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and more preferably a hydrogen atom.

Examples of the structural unit having an ethylenically unsaturated group include structural units represented by the following formula D1.

[ chemical formula 31]

In the formula D1, L ^D1 Represents a single bond or a divalent linking group, L ^D2 Represents a m +1 valent linking group, X ^D1 And X ^D2 Each independently represents-O-or-NR ^N -，R ^N Represents a hydrogen atom or an alkyl group, R ^D1 And R ^D2 Each independently represents a hydrogen atom or a methyl group, and m represents an integer of 1 or more.

In the formula D1, L ^D1 Preferably a single bond. At L ^D1 When the group represents a divalent linking group, the group is preferably an alkylene group, an arylene group, or a divalent group in which two or more of these groups are bonded, and more preferably an alkylene group or a phenylene group having 2 to 10 carbon atoms.

In the formula D1, L ^D2 Preferably, the group is represented by any one of the following formulae D2 to D6.

In the formula D1, X ^D1 And X ^D2 Are preferably-O-. And, in X ^D1 And X ^D2 At least one of them represents-NR ^N In the case of-R ^N Preferably a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and more preferably a hydrogen atom.

In the formula D1, R ^D1 Preferably methyl.

In the formula D1, m R ^D2 At least one of them is preferably methyl.

In formula D1, m is preferably an integer of 1 to 4, more preferably 1 or 2, and still more preferably 1.

[ chemical formula 32]

In the formulae D2 to D6, L ^D3 ～L ^D7 Represents a divalent linking group, L ^D5 And L ^D6 May be different from X in formula D1 ^D1 The wavy line portion represents the bonding site of formula (2) and X in the formula D1 ^D2 The bonding site of (3).

In the formula D3, L ^D3 Preferably an alkylene group, an arylene group or a group in which two or more of these groups are bonded, and more preferably an alkylene group having 1 to 10 carbon atoms, a phenylene group or a group in which two or more of these groups are bonded.

In the formula D4, L ^D4 Preferably an alkylene group, an arylene group or a group in which two or more of these groups are bonded, and more preferably an alkylene group having 1 to 10 carbon atoms, a phenylene group or a group in which two or more of these groups are bonded.

In the formula D5, L ^D5 Preferably an alkylene group, an arylene group or a group in which two or more of these groups are bonded, and more preferably an alkylene group having 1 to 10 carbon atoms, a phenylene group or a group in which two or more of these groups are bonded.

In the formula D6, L ^D6 Preferably alkylene, arylene or bothMore preferably, the group having at least two of these bonds is an alkylene group having 1 to 10 carbon atoms, a phenylene group or a group having two or more of these bonds.

In the formula D7, L ^D7 Preferably an alkylene group, an arylene group or a group in which two or more of these groups are bonded, and more preferably an alkylene group having 1 to 10 carbon atoms, a phenylene group or a group in which two or more of these groups are bonded.

Specific examples of the structural unit having an ethylenically unsaturated group are shown below, but the structural unit having an ethylenically unsaturated group contained in the binder polymer according to the present invention is not limited thereto. In the following specific examples, R represents a hydrogen atom or a methyl group, respectively.

[ chemical formula 33]

The content of the structural unit having an ethylenically unsaturated group in the specific binder polymer is preferably 5 to 60% by mass, and more preferably 10 to 30% by mass, with respect to the total mass of the specific binder polymer.

Structural units having acidic groups-

The specific binder polymer may contain a structural unit having an acidic group, and preferably does not contain a structural unit having an acidic group from the viewpoint of on-press developability and ink-receptivity.

Specifically, the content of the structural unit having an acidic group in the specific binder polymer is preferably 20% by mass or less, more preferably 10% by mass or less, and still more preferably 5% by mass or less. The lower limit of the content is not particularly limited, and may be 0% by mass.

The acid value of the specific binder polymer is preferably 160mgKOH/g or less, more preferably 80mgKOH/g or less, and still more preferably 40mgKOH/g or less. The lower limit of the acid value is not particularly limited, and may be 0mgKOH/g.

In the present invention, the acid value can be determined by a method based on JIS K0070:1992, etc.

Structural units having hydrophobic groups

From the viewpoint of ink-stainability, the specific binder polymer may contain a structural unit containing a hydrophobic group.

Examples of the hydrophobic group include an alkyl group, an aryl group, and an aralkyl group.

The structural unit containing a hydrophobic group is preferably a structural unit formed from an alkyl (meth) acrylate compound, an aryl (meth) acrylate compound, or an aralkyl (meth) acrylate compound, and more preferably a structural unit formed from an alkyl (meth) acrylate compound.

The alkyl group in the alkyl (meth) acrylate compound preferably has 1 to 10 carbon atoms. The alkyl group may be linear or branched, and may have a cyclic structure. Examples of the alkyl (meth) acrylate compound include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, cyclohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, and dicyclopentenyl (meth) acrylate.

The number of carbon atoms of the aryl group in the aryl (meth) acrylate compound is preferably 6 to 20, and a phenyl group is more preferable. The aryl group may have a known substituent. As the aryl (meth) acrylate compound, phenyl (meth) acrylate is preferably mentioned.

The number of carbon atoms of the alkyl group in the aralkyl (meth) acrylate compound is preferably 1 to 10. The alkyl group may be linear or branched, and may have a cyclic structure. The number of carbon atoms of the aryl group in the aralkyl (meth) acrylate compound is preferably 6 to 20, and a phenyl group is more preferable. As the aralkyl (meth) acrylate compound, benzyl (meth) acrylate is preferably mentioned.

The content of the structural unit having a hydrophobic group in the specific binder polymer is preferably 5 to 50% by mass, and more preferably 10 to 30% by mass, with respect to the total mass of the specific binder polymer.

Structural units having hydrophilic groups

From the viewpoint of improving UV brush resistance, chemical resistance, and on-press developability, the specific binder polymer may contain a structural unit having a hydrophilic group.

Examples of the hydrophilic group include-OH, -CN and-CONR ¹ R ² 、-NR ² COR ¹ (R ¹ 、R ² Each independently represents a hydrogen atom, an alkyl group, an alkenyl group or an aryl group. R ¹ And R ² May be bonded to form a ring. ) -NR ³ R ⁴ 、-N ⁺ R ³ R ⁴ R ⁵ X ^- (R ³ ～R ⁵ Each independently represents an alkyl group having 1 to 8 carbon atoms, X ^- Representing a counter anion), a group represented by the following formula PO, and the like.

Among these hydrophilic groups, -OH, -CONR is preferable ¹ R ² Or a group represented by the formula PO, more preferably-OH or a group represented by the formula PO, and still more preferably-OH.

[ chemical formula 34]

In the formula PO, L ^P Each independently represents an alkylene group, R ^P Represents a hydrogen atom or an alkyl group, and n represents an integer of 1 to 100.

In the formula PO, L is preferred ^P Each independently vinyl, 1-methylvinyl or 2-methylvinyl, more preferably vinyl.

In the formula PO, R ^P The alkyl group is preferably a hydrogen atom or an alkyl group having 1 to 18 carbon atoms, more preferably a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, still more preferably a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and particularly preferably a hydrogen atom or a methyl group.

In formula PO, n is preferably an integer of 1 to 10, more preferably an integer of 1 to 4.

The structural unit having a hydrophilic group is preferably a structural unit formed from a hydroxyalkyl (meth) acrylate compound, and more preferably a structural unit formed from a hydroxyethyl (meth) acrylate compound.

The content of the structural unit having a hydrophilic group in the specific binder polymer is preferably 5 to 60% by mass, and more preferably 10 to 30% by mass, with respect to the total mass of the specific binder polymer.

Other structural units-

Certain binder polymers may also contain other structural units. The other constituent unit may include, but is not particularly limited to, a constituent unit other than the above-described constituent units, and examples thereof include a constituent unit formed from an acrylamide compound, a vinyl ether compound, and the like.

Examples of the acrylamide compound include (meth) acrylamide, N-methyl (meth) acrylamide, N-ethyl (meth) acrylamide, N-propyl (meth) acrylamide, N-butyl (meth) acrylamide, N '-dimethyl (meth) acrylamide, N' -diethyl (meth) acrylamide, N-hydroxyethyl (meth) acrylamide, N-hydroxypropyl (meth) acrylamide, and N-hydroxybutyl (meth) acrylamide.

Examples of the vinyl ether compound include methyl vinyl ether, ethyl vinyl ether, propyl vinyl ether, n-butyl vinyl ether, tert-butyl vinyl ether, 2-ethylhexyl vinyl ether, n-nonyl vinyl ether, lauryl vinyl ether, cyclohexyl methyl vinyl ether, 4-methylcyclohexyl methyl vinyl ether, benzyl vinyl ether, dicyclopentenyl vinyl ether, 2-dicyclopentenyloxyethyl vinyl ether, methoxyethyl vinyl ether, ethoxyethyl vinyl ether, butoxyethyl vinyl ether, methoxyethoxyethyl vinyl ether, ethoxyethoxyethoxyethyl vinyl ether, methoxypolyethylene glycol vinyl ether, tetrahydrofurfuryl vinyl ether, 2-hydroxyethyl vinyl ether, 2-hydroxypropyl vinyl ether, 4-hydroxybutyl vinyl ether, 4-hydroxymethylcyclohexyl methyl vinyl ether, diethylene glycol monovinyl ether, polyethylene glycol vinyl ether, chloroethyl vinyl ether, chlorobutyl vinyl ether, chloroethoxyethyl vinyl ether, phenethyl vinyl ether, phenoxypolyethylene glycol vinyl ether, and the like.

The content of the other structural unit in the specific binder polymer is preferably 5 to 50% by mass, and more preferably 10 to 30% by mass, based on the total mass of the specific binder polymer.

Method for producing specific binder polymers

The method for producing the specific binder polymer is not particularly limited, and can be produced by a known method.

For example, the polymerizable compound is obtained by polymerizing a styrene compound, an acrylonitrile compound, and, if necessary, at least one compound selected from the group consisting of the N-vinyl heterocyclic compound, the compound used for forming the structural unit having an ethylenically unsaturated group, the compound used for forming the structural unit having an acidic group, the compound used for forming the structural unit having a hydrophobic group, and the compound used for forming the other structural unit by a known method.

Molecular weight-

The weight average molecular weight of the specific binder polymer is preferably 3,000 to 300,000, more preferably 5,000 to 100,000.

Specific examples-

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

[ chemical formula 35]

In the specific examples described above, the content ratio of each constituent unit can be appropriately changed in accordance with the preferable range of the content of each constituent unit.

The weight average molecular weight of each compound shown in the specific examples can be appropriately changed depending on the preferable range of the weight average molecular weight of the specific binder polymer.

Content-

The image recording layer may contain one specific binder polymer alone or two or more types may be used simultaneously.

The content of the specific binder polymer is preferably 5% by mass or more and 95% by mass or less, more preferably 7% by mass or more and 80% by mass or less, and further preferably 10% by mass or more and 60% by mass or less, with respect to the total mass of the image recording layer.

[ polymerization initiator ]

The polymerization initiator is a compound that initiates and accelerates polymerization of the polymerizable compound. As the polymerization initiator, a known thermal polymerization initiator, a compound having a bond with a small bond dissociation energy, a photopolymerization initiator, an electron accepting type polymerization initiator described later, an electron donating type polymerization initiator described later, and the like can be used. Specifically, the radical polymerization initiator described in paragraphs 0092 to 0106 of Japanese patent application laid-open No. 2014-104631 can be used.

Among the polymerization initiators, onium salt compounds are preferable. Among them, particularly preferred are iodonium salts and sulfonium salts. The specific compound preferable for each salt is the same as the compounds described in paragraphs 0104 to 0106 of Japanese patent application laid-open No. 2014-104631.

The content of the 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 mass of the image recording layer. In this range, more excellent sensitivity and more excellent stain resistance of non-image portions during printing can be obtained.

In addition, although one kind of polymerization initiator may be used alone or two or more kinds of polymerization initiators may be used simultaneously, the polymerization initiator in the image recording layer preferably includes at least one polymerization initiator selected from the group consisting of an electron donating polymerization initiator and an electron accepting polymerization initiator, and more preferably includes an electron donating polymerization initiator and an electron accepting polymerization initiator, from the viewpoints of color developability, color developability with time after exposure, and UV resistance in the obtained lithographic printing plate precursor.

In addition, the polymerization initiator preferably contains a compound in which a counter salt is formed from an electron donating polymerization initiator and an electron accepting polymerization initiator, from the viewpoints of color developability, color developability with time after exposure, and UV resistance in the obtained lithographic printing plate precursor.

Electron-donating polymerization initiators

The image recording layer preferably contains an electron donating polymerization initiator as the polymerization initiator, from the viewpoints of color developability, color developability with time after exposure, and UV resistance in the lithographic printing plate precursor obtained.

It is considered that the electron donating type polymerization initiator contributes to the improvement of chemical resistance and brush resistance in the lithographic printing plate. Examples of the electron donating polymerization initiator include the following 5 types.

(i) Alkyl or arylate type complexes: it is believed that the carbon-heterobonds are oxidatively cleaved to generate active radicals. Specifically, a borate compound and the like can be given.

(ii) Aminoacetic acid compound: it is considered that the C — X bond on the carbon adjacent to nitrogen is cleaved by oxidation to generate an active radical. As X, a hydrogen atom, a carboxyl group, a trimethylsilyl group or a benzyl group is preferable. Specific examples thereof include N-phenylglycine (which may have a substituent on the phenyl group), N-phenyliminodiacetic acid (which may have a substituent on the phenyl group), and the like.

(iii) A sulfur-containing compound: the compound obtained by substituting the nitrogen atom of the glycine compound with a sulfur atom can generate an active radical by the same action. Specifically, there may be mentioned phenylthioacetic acid (which may have a substituent in the phenyl group), and the like.

(iv) A tin-containing compound: the compound obtained by substituting the nitrogen atom of the glycine compound with a tin atom can generate an active radical by the same action.

(v) Sulfinates: can generate active free radicals by oxidation. Specific examples thereof include sodium arylsulfinate and the like.

Among these electron-donating polymerization initiators, the image-recording layer preferably contains a borate compound. The borate compound is preferably a tetraarylborate compound or a monoalkyltriarylborate compound, and from the viewpoint of stability of the compound, a tetraarylborate compound is more preferably used, and a tetraphenylborate compound is particularly preferably used.

The counter cation of the borate compound is not particularly limited, but is preferably an alkali metal ion or a tetraalkylammonium ion, and more preferably a sodium ion, a potassium ion or a tetrabutylammonium ion.

Specific examples of the borate compound include sodium tetraphenylborate.

From the viewpoint of chemical resistance and UV brushing resistance, the highest occupied orbital (HOMO) of the electron donating polymerization initiator used in the present invention is preferably-6.00 eV or more, more preferably-5.95 eV or more, and still more preferably-5.93 eV or more.

The upper limit is preferably-5.00 eV or less, and more preferably-5.40 eV or less.

In the present invention, the calculation of the Highest Occupied Molecular Orbital (HOMO) and the Lowest Unoccupied Molecular Orbital (LUMO) is performed by the following method.

First, the counter anion in the compound to be calculated is ignored.

Quantum chemistry computing software Gaussian09 was used and structure optimization was performed with DFT (B3 LYP/6-31G (d)).

For MO (molecular orbital) energy calculation, the structure obtained by the above structure optimization is used and performed as DFT (B3 LYP/6-31+ G (d, p)/CPCM (solvent) = methanol)).

The MO energy Ebare (unit: hartree) obtained by the above MO energy calculation is converted into Escaped (unit: eV) which is used as the value of HOMO and LUMO in the present invention by the following formula.

Escaled＝0.823168×27.2114×Ebare-1.07634

27.2114 is a coefficient for converting hartree to eV only, 0.823168 and-1.07634 are adjustment coefficients, and HOMO and LUMO of the compound to be calculated are determined as the actual values.

Hereinafter, preferred specific examples of the electron donating polymerization initiator are shown as B-1 to B-8, but the electron donating polymerization initiator is not limited thereto. In the following chemical formula, bu represents an n-butyl group, and Z represents a counter cation.

As the counter cation represented by Z, na may be mentioned ⁺ 、K ⁺ And N ⁺ (Bu) ₄ And so on. Bu mentioned above represents an n-butyl group.

Further, as the counter cation represented by Z, an onium ion in an electron acceptor type polymerization initiator described later can be preferably used.

[ chemical formula 36]

[ chemical formula 37]

The electron-donating polymerization initiator may be added alone or in combination of two or more.

The content of the electron donating polymerization initiator is preferably 0.01 to 30% by mass, more preferably 0.05 to 25% by mass, and further preferably 0.1 to 20% by mass, with respect to the total mass of the image recording layer, from the viewpoints of color developability, color developability with time after exposure, developability, and UV resistance in the obtained lithographic printing plate precursor.

[ Electron acceptors type polymerization initiators ]

The image recording layer preferably contains an electron accepting polymerization initiator from the viewpoints of color developability, color developability with time after exposure, developability, and UV resistance in the lithographic printing plate precursor obtained.

The electron accepting type polymerization initiator used in the present invention is a compound which generates a polymerization initiating species such as a radical or a cation by light, heat or both of these energies, and can be appropriately selected from known thermal polymerization initiators, compounds having a bond with a small bond dissociation energy, photopolymerization initiators and the like.

The electron accepting type polymerization initiator is preferably a radical polymerization initiator, and more preferably an onium salt compound.

The electron-accepting type polymerization initiator is preferably an infrared photosensitive polymerization initiator.

The electron accepting type polymerization initiator may be used singly or in combination of two or more.

Examples of the radical polymerization initiator include (a) an organic halide, (b) a carbonyl compound, (c) an azo compound, (d) an organic peroxide, (e) a metallocene compound, (f) an azide compound, (g) a hexaarylbiimidazole compound, (i) a disulfone compound, (j) an oxime ester compound, and (k) an onium compound.

(a) As the organic halide, for example, compounds described in paragraphs 0022 to 0023 of jp 2008-195018 a are preferable.

(b) As the carbonyl compound, for example, a compound described in paragraph 0024 of jp 2008-195018 a is preferable.

(c) As the azo compound, for example, an azo compound described in Japanese patent application laid-open No. 8-108621 and the like can be used.

(d) As the organic peroxide, for example, a compound described in paragraph 0025 of japanese patent application laid-open No. 2008-195018 is preferable.

(e) As the metallocene compound, for example, a compound described in paragraph 0026 of jp 2008-195018 a is preferable.

(f) Examples of the azide compound include 2,6-bis (4-azidobenzylidene) -4-methylcyclohexanone and the like.

(g) As the hexaarylbiimidazole compound, for example, a compound described in paragraph 0027 of japanese patent application laid-open No. 2008-195018 is preferable.

(i) Examples of the disulfone compound include those described in Japanese patent application laid-open Nos. 61-166544 and 2002-328465.

(j) The oxime ester compound is preferably a compound described in paragraphs 0028 to 0030 of jp 2008-195018 a, for example.

Among the above electron-accepting polymerization initiators, oxime ester compounds and onium salt compounds are preferable from the viewpoint of curability. Among these, from the viewpoint of UV brush resistance, an iodonium salt compound, a sulfonium salt compound, or an azinium salt compound is preferable, an iodonium salt compound or a sulfonium salt compound is more preferable, and an iodonium salt compound is even more preferable.

Specific examples of these compounds are shown below, but the present invention is not limited thereto.

As examples of the iodonium salt compound, a diaryl iodonium salt compound is preferable, an electron donating group is particularly preferable, for example, a diphenyl iodonium salt compound substituted with an alkyl group or an alkoxy group is more preferable, and an asymmetric diphenyl iodonium salt compound is preferable. Specific examples include diphenyliodonium = hexafluorophosphate, 4-methoxyphenyl-4- (2-methylpropyl) phenyliodonium = hexafluorophosphate, 4- (2-methylpropyl) phenyl-p-tolyliodonium = hexafluorophosphate, 4-hexyloxyphenyl-2,4,6-trimethoxyphenyliodonium = hexafluorophosphate, 4-hexyloxyphenyl-2,4-diethoxyphenyliodonium = tetrafluoroborate, 4-octyloxyphenyl-2,4,6-trimethoxyphenyliodonium = 1-perfluorobutanesulfonate, 4-octyloxyphenyl-2,4,6-trimethoxyphenyliodonium = hexafluorophosphate, and bis (4-tert-butylphenyl) iodonium = tetraphenylborate.

As an example of the sulfonium salt compound, a triarylsulfonium salt compound is preferable, and particularly, an electron-withdrawing group is preferable, and for example, a triarylsulfonium salt compound in which at least a part of groups on an aromatic ring is substituted with a halogen atom is preferable, and a triarylsulfonium salt compound in which the total number of substitution of halogen atoms on an aromatic ring is 4 or more is more preferable. Specific examples thereof include triphenylsulfonium = hexafluorophosphate, triphenylsulfonium = benzoyl formate, bis (4-chlorophenyl) phenylsulfanium = benzoyl formate, bis (4-chlorophenyl) -4-tolylsulfonium = tetrafluoroborate, tris (4-chlorophenyl) sulfonium =3,5-bis (methoxycarbonyl) benzenesulfonate, tris (4-chlorophenyl) sulfonium = hexafluorophosphate, and tris (2,4-dichlorophenyl) sulfonium = hexafluorophosphate.

The counter anion of the iodonium salt compound and the sulfonium salt compound is preferably a sulfonamide or sulfonimide, and more preferably sulfonimide.

As the sulfonamide, aryl sulfonamide is preferable.

Also, as the sulfonimide, bis-aryl sulfonimide is preferable.

Specific examples of the sulfonamide or the sulfonimide are shown below, but the present invention is not limited thereto. In the following specific examples, ph represents a phenyl group, me represents a methyl group, and Et represents an ethyl group.

[ chemical formula 38]

In a preferred embodiment of the present invention, a salt is formed from the electron accepting polymerization initiator and the electron donating polymerization initiator.

Specifically, for example, there is a mode in which the onium salt compound is a salt of an onium ion and an anion (for example, tetraphenylborate anion) in the electron donating polymerization initiator. More preferably, the iodonium borate compound is one in which a salt is formed from an iodonium cation (for example, a di-to-tri-iodonium cation) in the iodonium salt compound described later and a borate anion in the electron donating polymerization initiator.

Specific examples of the form in which the electron accepting polymerization initiator and the electron donating polymerization initiator form a salt are shown below, but the present invention is not limited thereto.

[ chemical formula 39]

In addition, from the viewpoint of color developability, color developability with time after exposure, developability, and UV resistance in the obtained lithographic printing plate precursor, a compound represented by the following formula (I) can be preferably used as the electron accepting type polymerization initiator.

[ chemical formula 40]

In the formula, X represents a halogen atom, and specifically, a fluorine atom, a chlorine atom, a bromine atom and an iodine atom are exemplified. Among these, a chlorine atom and a bromine atom are preferable because of their excellent sensitivity, and a bromine atom is particularly preferable.

A represents a group selected from-CO-, -SO-, -SO ₂ -, -PO-and-PO ₂ -a linker having a valence of 2 in the group consisting. Among them, more preferred are-CO-, -SO-and-SO ₂ -CO-and-SO-are particularly preferred ₂ -。R ^X1 And R ^X2 Each independently represents a hydrogen atom or a 1-valent hydrocarbon group having 1 to 20 carbon atoms.

Examples of the hydrocarbon constituting the hydrocarbon group include the hydrocarbons described in paragraphs 0013 to 0014 of Japanese patent application laid-open No. 2002-162741, and specific examples of the hydrocarbon include methane, ethane, propane, butane, hexane, nonane, decane, octadecane, cyclopentane, cyclohexane, adamantane, norbornane, decalin, and tricyclo [5.2.1.0 ] naphthalene ^2,6 ]Decane, ethene, propene, 1-butene, 1-hexene, 1-Heptadecene (Heptadecene), 2-butene, 2-hexene, 4-nonene, 7-tetradecene, butadiene, piperylene, 1,9-decadiene (decadiene), cyclopentene, cyclohexene, cyclooctene, 1,4-cyclohexadiene, 1,5-cyclooctadiene, 1,5,9-cyclododecatriene, norbornene, octahydronaphthalene, bicyclo [2.2.1]Aliphatic hydrocarbons having 1 to 30 carbon atoms such as heptane-2,5-diene, acetylene, 1-propyne, 2-hexyne (Hexyn), and the like; aromatic hydrocarbons such as benzene, naphthalene, anthracene, indene, and fluorene.

The carbon atoms constituting the hydrocarbon group may be substituted with one or more hetero atoms selected from an oxygen atom, a nitrogen atom and a sulfur atom.

As the substituent, there may be mentioned, in addition to hydrogen, a non-metallic atomic group having a valence of 1, and there may be mentioned a halogen atom (-F, -Br, -Cl, -I), a hydroxyl group, an alkoxy group, an aryloxy group, a mercapto group, an alkylthio group, an arylthio group, an alkyldithio group, an aryldithio group, an amino group, an N-alkylamino group, an N, N-dialkylamino group, an N-arylamino group, an N, N-diarylamino group, an N-alkyl-N-arylamino group, an acyloxy group, a carbamoyloxy group, an N-alkylcarbamoyloxy group, an N-arylcarbamoyloxy group, an N, N-dialkylcarbamoyloxy group, N, N-diarylcarbamoyloxy, N-alkyl-N-arylcarbamoyloxy, alkylsulfoxy, arylsulfonyloxy, thioyl, acylamino, N-alkylamido, N-arylacylamino, ureido, N '-alkylureido, N' -dialkylureido, N '-arylureido, N', N '-diaryl ureido, N' -alkyl-N '-aryl ureido, N-alkyl ureido, N-aryl ureido, N' -alkyl-N-alkyl ureido, N '-alkyl-N-aryl ureido, N' -dialkyl-N-alkyl ureido, N '-dialkyl-N-aryl ureido, N' -aryl-N-alkyl ureido, N '-aryl-N-aryl ureido, N' -diaryl-N-alkyl ureido, N ', N' -diaryl-N-arylureido, N '-alkyl-N' -aryl-N-alkylureido, N '-alkyl-N' -aryl-N-arylureido, alkoxycarbonylamino, aryloxycarbonylamino, N-alkyl-N-alkoxycarbonylamino, N-alkyl-N-aryloxycarbonylamino, N-aryl-N-alkoxycarbonylamino, N-aryl-N-aryloxycarbonylamino, formyl, acyl, carboxyl and their conjugated bases, alkoxycarbonyl, aryloxycarbonyl, carbamoyl, N-alkylcarbamoyl, N-dialkylcarbamoyl, N-arylcarbamoyl, N-diarylcarbamoyl, N-alkyl-N-arylcarbamoyl, alkylsulfinyl, arylsulfinyl, alkylsulfonyl, arylsulfonyl, sulfo (-SO) ₃ H) And a conjugate base thereof, an alkoxysulfonyl group, an aryloxysulfonyl group, a sulfamoyl group, an N-alkylsulfamoyl group, N-dialkylaminosulfinyl, N-arylaminosulfinyl, N-diarylaminosulfinyl, N-alkyl-N-arylaminosulfinyl, sulfamoyl, N-alkylsulfamoyl, -N, N-dialkylsulfamoyl, -N-arylsulfamoyl, -N, N-diarylsulfamoyl, -N-alkyl-N-arylsulfamoyl, -N-acylsulfamoyl and its conjugated base, -N-alkylsulfonylsulfamoyl (-SO) ₂ NHSO ₂ (alkyl)) and its conjugated base, N-arylsulfonylaminosulfonyl (-SO) ₂ NHSO ₂ (aryl)) and a conjugated base thereof, an N-alkylsulfonylcarbamoyl group (-CONHSO) ₂ (alkyl)) and the conjugated base thereof, N-arylsulfonylcarbamoyl (-CONHSO) ₂ (aryl)) and a conjugated basic group thereof, an alkoxysilyl group (-Si (Oalkyl) ₃ ) Aryloxysilyl (-Si (Oaryl) ₃ ) Hydroxysilyl (-Si (OH) ₃ ) And its conjugated base group, phosphono (-PO) ₃ H ₂ ) And its conjugated basic group, dialkyl phosphonyl (-PO) ₃ (alkyl) ₂ ) Diaryl phosphonyl (-PO) ₃ (aryl) ₂ ) Alkyl aryl phosphonyl (-PO) ₃ (alkyl) (aryl)), monoalkyl phosphono (-PO) ₃ H (alkyl)) and its conjugated base, monoarylphosphono (-PO) ₃ H (aryl)) and its conjugate base, phosphonoxy (-OPO) ₃ H ₂ ) And its conjugated basic group, dialkyl phosphonoxy (-OPO) ₃ (alkyl) ₂ ) Diaryl phosphonyloxy (-OPO) ₃ (aryl) ₂ ) Alkyl aryl phosphonoxy (-OPO) ₃ (alkyl) (aryl)), monoalkylphosphonoxy (-OPO) ₃ H (alkyl)) and its conjugated base, monoarylphosphonoxy (-OPO) ₃ H (aryl)) and its conjugate base, cyano, nitro, dialkyloxyboronyl (-B (alkyl) ₂ ) Diaryloxyboronyl (-B (aryl) ₂ ) Alkyl aryl oxyboronyl (-B (alkyl)), dihydroxy oxyboronyl (-B (OH) ₂ ) And its conjugate base, alkylhydroxyoxyboronyl (-B (alkyl) (OH)) and its conjugate base, arylhydroxyoxyboronyl (-B (aryl) (OH)) and its conjugate base, aryl, alkyl, alkenyl, alkynyl.

These substituents may, if possible, be bonded to each other to form a ring or to a substituted hydrocarbon group to form a ring, and the substituents may be further substituted.

Preferred substituents include halogen atoms, alkoxy groups, aryloxy groups, alkyl groups, alkenyl groups, alkynyl groups, and aryl groups.

m ^x And n ^x Each represents an integer of 1 to 3. Wherein m is ^x +n ^x And (4) =2 to 4. From the viewpoint of sensitivity, m is preferable ^x =1 and n ^x =3 or m ^x =2 and n ^x And (5) =2. At m ^x And n ^x When the number is 2 or more, (R1-A) and X may be different from each other. And, even at m ^x =1 and n ^x In case of =1, R ^x2 May be different from each other.

Among the compounds represented by the above formula (I), the compounds represented by the following formulae (II) and (III) are preferable because of excellent visibility.

[ chemical formula 41]

In the formulae (II) and (III), X has the same meaning as in the formula (I), and R ³ 、R ⁴ And R ⁵ Each independently represents a 1-valent hydrocarbon group having 1 to 20 carbon atoms.

Wherein R is ³ 、R ⁴ And R ⁵ Aryl groups are preferred, and aryl groups substituted with an amide group are more preferred because they have an excellent balance between sensitivity and storage stability.

Among the compounds represented by the following formulae (II) and (III), the compound represented by the formula (IV) is particularly preferable.

[ chemical formula 42]

In the formula (IV), R ⁴ And R ⁵ Each independently represents a hydrogen atom or a 1-valent hydrocarbon group having 1 to 20 carbon atoms. p and q represent an integer of 1 to 5. Wherein p + q =2 to 6.

Specific examples of the electron accepting type polymerization initiator represented by the above formula (I) include compounds represented by the following formulae, but the present invention is not limited thereto.

[ chemical formula 43]

[ chemical formula 44]

[ chemical formula 45]

[ chemical formula 46]

[ chemical formula 47]

[ chemical formula 48]

[ chemical formula 49]

In the present invention, in the case where the image-recording layer contains an onium ion and an anion in the above-mentioned electron-donating polymerization initiator, the image-recording layer contains an electron-accepting polymerization initiator and an electron-donating polymerization initiator.

From the viewpoint of chemical resistance and UV brush resistance, the Lowest Unoccupied Molecular Orbital (LUMO) of the electron accepting type polymerization initiator is preferably-3.00 eV or less, more preferably-3.02 eV or less.

The lower limit is preferably-3.80 eV or more, and more preferably-3.60 eV or more.

The electron accepting type polymerization initiator may be added in one kind alone, or two or more kinds may be used simultaneously.

The content of the electron-accepting 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 mass of the image recording layer, from the viewpoint of color developability and UV resistance in the lithographic printing plate precursor obtained.

A compound comprising a counter salt formed from an electron donating polymerization initiator and an electron accepting polymerization initiator

The polymerization initiator preferably contains a compound having a counter salt formed from an electron donating polymerization initiator and an electron accepting polymerization initiator, from the viewpoints of color developability, color developability with time after exposure, and UV resistance in the lithographic printing plate precursor obtained.

The compound having a counter salt formed from the electron donating polymerization initiator and the electron accepting polymerization initiator is preferably a compound having a counter salt formed from an anion in the electron donating polymerization initiator and a cation in the electron accepting polymerization initiator, more preferably a compound having a counter salt formed from an onium cation and a borate anion, even more preferably a compound having a counter salt formed from an iodonium cation or a sulfonium cation and a borate anion, and particularly preferably a compound having a counter salt formed from a diaryliodonium cation or a triarylsulfonium cation and a tetraarylborate anion, from the viewpoints of color developability and UV resistance in the obtained lithographic printing plate.

Preferred embodiments of the anion in the electron-donating polymerization initiator and the cation in the electron-accepting polymerization initiator are the same as the preferred embodiments of the anion in the electron-donating polymerization initiator and the cation in the electron-accepting polymerization initiator.

The counter salt formed by the electron donating polymerization initiator and the electron accepting polymerization initiator may be used singly or in combination. The electron donating polymerization initiator may be used together with the electron donating polymerization initiator, or may be used together with the electron accepting polymerization initiator.

The content of the compound having a counter salt formed from the electron donating polymerization initiator and the electron accepting 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, based on the total mass of the image recording layer, from the viewpoints of color developability and UV resistance in the obtained lithographic printing plate.

[ relationship between Electron donating polymerization initiator, electron accepting polymerization initiator, and Infrared absorber ]

From the viewpoint of color developability and UV resistance in the obtained lithographic printing plate, the image recording layer contains the electron donating polymerization initiator, the electron accepting polymerization initiator, and the specific infrared absorber, and it is preferable that the HOMO of the electron donating polymerization initiator is-6.0 eV or more and the LUMO of the electron accepting polymerization initiator is-3.0 eV or less.

More preferred embodiments of the HOMO of the electron donating polymerization initiator and the LUMO of the electron accepting polymerization initiator are as described above.

It is presumed that in the image recording layer of the present invention, the electron donating polymerization initiator, the infrared absorber, and the electron accepting polymerization initiator transmit energy as described in the following chemical formula, for example.

Therefore, it is considered that if the HOMO of the electron donating polymerization initiator is-6.0 eV or more and the LUMO of the electron accepting polymerization initiator is-3.0 eV or less, the generation efficiency of radicals is improved, and thus the chemical resistance and UV brush resistance are more easily excellent.

It is also presumed that a part of the specific infrared absorber may promote decomposition by infrared exposure by one electron donor from the electron-donating polymerization initiator.

[ chemical formula 50]

The difference between the HOMO of the electron donating polymerization initiator and the HOMO of the infrared absorber is preferably 1.00eV to-0.200 eV, and more preferably 0.700eV to-0.100 eV, from the viewpoint of UV brush resistance and chemical resistance. A negative value indicates that the HOMO of the electron-donating polymerization initiator is higher than the HOMO of the infrared absorber.

In addition, the difference between the LUMO of the infrared absorber and the LUMO of the electron accepting type polymerization initiator is preferably 1.00eV to-0.200 eV, and more preferably 0.700eV to-0.100 eV, from the viewpoint of UV brush resistance and chemical resistance. In addition, a negative value indicates that the LUMO of the infrared absorber is higher than the LUMO of the electron accepting polymerization initiator.

[ polymerizable Compound ]

The image recording layer in the present invention contains a polymerizable compound.

In the present invention, even if the compound is a compound having polymerizability, the compound corresponding to the specific binder polymer, the polymer particles described later, and the binder polymer other than the specific binder polymer described later is not a compound having polymerizability.

From the viewpoint of on-press developability and UV resistance in the obtained lithographic printing plate, the molecular weight (weight average molecular weight in the case of having a molecular weight distribution) of the polymerizable compound is preferably 50 or more and less than 2,500, and more preferably 50 or more and 2,000 or less.

From the viewpoint of UV resistance in the obtained lithographic printing plate, the mass of the ethylenically unsaturated bond per 1mol of the polymerizable compound (also referred to as "ethylenically unsaturated bond equivalent") is preferably 200g/mol or less, more preferably 50g/mol or more and 200g/mol or less, further preferably 80g/mol or more and 180g/mol or less, and particularly preferably 100g/mol or more and 150g/mol or less.

In the present invention, the equivalent of the ethylenically unsaturated bond of the polymerizable compound can be specifically determined, for example, as follows.

Equivalent of ethylenic unsaturation of dipentaerythritol hexaacrylate (DPHA, molecular weight 578, six ethylenic unsaturations): 578/6 =96.3 (g/mol)

Ethylenic unsaturation equivalent of styrene (molecular weight 104, one ethylenic unsaturation): 104/1 =104 (g/mol)

Ethylenic unsaturation equivalent of "mixture of 10g of DPHA and 20g of styrene": (10 + 20)/{ 10/96.3+20/104} =101 (g/mol)

The equivalent weight of the ethylenically unsaturated bond in the present invention can be determined by the above-mentioned calculation method by determining the molecular weight and the number of ethylenically unsaturated bonds of the polymerizable compound and the composition of the polymerizable compound in the image recording layer by known methods.

From the viewpoint of on-press developability and UV resistance in the obtained lithographic printing plate, the ClogP value of the polymerizable compound is preferably 6 or less, more preferably 2 or more and 6 or less, further preferably 3 or more and 6 or less, and particularly preferably 5 or more and 6 or less.

The ClogP value in the present invention is a value obtained by calculating the log logP of the common logarithm of the partition coefficient P of 1-octanol and water, and is a calculated value based on Chem Draw Ultra ver.12.0.2.1076 (Cambridge Companies).

The polymerizable compound used in the present invention may be, for example, a radical polymerizable compound or a cationic polymerizable compound.

Examples of the polymerizable group of the polymerizable compound include a group having an ethylenically unsaturated bond, an epoxy group, a methylol group, and an alkoxymethyl group.

The polymerizable compound is preferably an addition polymerizable compound (ethylenically unsaturated bond compound) containing a group having at least one ethylenically unsaturated bond. The ethylenically unsaturated compound is preferably a compound having at least one terminal ethylenically unsaturated bond, and more preferably a compound having two or more terminal ethylenically unsaturated bonds.

Examples of the group having an ethylenically unsaturated bond include a vinyl group, (meth) allyl group, and (meth) acryloyl group, but from the viewpoint of UV resistance in the obtained lithographic printing plate, a vinyl group or (meth) acryloyl group is preferable.

The polymerizable compound has a chemical form such as a monomer, a prepolymer, that is, a dimer, a trimer, or an oligomer, or a mixture thereof.

Among them, the polymerizable compound preferably contains a polymerizable compound having 3 or more functions, more preferably contains a polymerizable group having 7 or more functions, and still more preferably contains a polymerizable group having 10 or more functions, from the viewpoint of UV resistance in the obtained lithographic printing plate. In view of UV resistance in the obtained lithographic printing plate, the polymerizable compound preferably contains an ethylenically unsaturated compound having 3 or more functions (preferably 7 or more functions, more preferably 10 or more functions), and more preferably contains a (meth) acrylic compound having 3 or more functions (preferably 7 or more functions, more preferably 10 or more functions).

Examples of the monomer include unsaturated carboxylic acids (e.g., acrylic acid, methacrylic acid, itaconic acid, crotonic acid, isocrotonic acid, and maleic acid), esters thereof, and amides thereof, and esters of unsaturated carboxylic acids and polyhydric alcohol compounds, and amides of unsaturated carboxylic acids and polyhydric amine compounds are preferably used. Further, addition reaction products of unsaturated carboxylic acid esters or amides having a nucleophilic substituent such as a hydroxyl group, an amino group, or a mercapto group with monofunctional or polyfunctional isocyanates or epoxies, dehydration condensation reaction products with monofunctional or polyfunctional carboxylic acids, and the like are also preferably used. Further, addition reaction products of unsaturated carboxylic acid esters or amides having electrophilic substituent groups such as isocyanate group and epoxy group with monofunctional or polyfunctional alcohols, amines and thiols are also preferable, and substitution reaction products of unsaturated carboxylic acid esters or amides having leaving substituent groups such as halogen atom and tosyloxy group with monofunctional or polyfunctional alcohols, amines and thiols are more preferable. As another example, the above-mentioned group of compounds in which the unsaturated carboxylic acid is substituted with an unsaturated phosphonic acid, styrene, vinyl ether, or the like can also be used. These are described in, for example, JP-A-2006-508380, JP-A-2002-287344, JP-A-2008-256850, JP-A-2001-342222, JP-A-9-179296, JP-A-9-179297, JP-A-9-179298, JP-A-2004-294935, JP-A-2006-243493, JP-A-2002-275129, JP-A-2003-064130, JP-A-2003-280187, and JP-A-10-333321.

Specific examples of the monomer of the polyol compound and the ester of the unsaturated carboxylic acid include ethylene glycol diacrylate, 1,3-butanediol diacrylate, tetramethylene glycol diacrylate, propylene glycol diacrylate, trimethylolpropane triacrylate, hexanediol diacrylate, tetraethylene glycol diacrylate, neopentyl glycol tetraacrylate, sorbitol triacrylate, ethylene oxide isocyanurate (EO) -modified triacrylate, and polyester acrylate oligomer. Examples of the methacrylate include tetramethylene glycol dimethacrylate, neopentyl glycol dimethacrylate, trimethylolpropane trimethacrylate, ethylene glycol dimethacrylate, neopentyltetraol trimethacrylate, bis [ p- (3-methacryloyloxy-2-hydroxypropoxy) phenyl ] dimethylmethane, bis [ p- (methacryloyloxyethoxy) phenyl ] dimethylmethane, and the like. Specific examples of the amide monomer of the polyamine compound and the unsaturated carboxylic acid include methylenebisacrylamide, methylenebismethacrylamide, 1,6-hexamethylenebisacrylamide, 1,6-hexamethylenebismethacrylamide, diethylenetriaminetriacrylate, xylylenebisacrylamide, and diphenylenedimethacrylamide.

Further, urethane addition polymerizable compounds produced by an addition reaction of isocyanate and hydroxyl group are also preferable, and specific examples thereof include vinyl urethane compounds containing two or more polymerizable vinyl groups in 1 molecule obtained by adding a polyisocyanate compound having two or more isocyanate groups in 1 molecule and a hydroxyl group-containing vinyl monomer represented by the following formula (M) as described in japanese patent publication No. 48-041708.

CH ₂ ＝C(R ^M4 )COOCH ₂ CH(R ^M5 )OH (M)

In the formula (M), R ^M4 And R ^M5 Each independently represents a hydrogen atom or a methyl group.

Also, urethane acrylates described in Japanese patent laid-open Nos. Sho 51-037193, japanese patent publication No. Hei 2-032293, japanese patent publication No. Hei 2-016765, japanese patent laid-open No. 2003-344997, japanese patent laid-open No. 2006-065210, japanese patent publication No. Sho 58-049860, japanese patent publication No. Sho 56-017654, japanese patent publication No. Sho 62-039417, japanese patent publication No. Sho 62-039418, japanese patent laid-open No. 2000-250211, japanese patent laid-open No. 2007-094138, urethane compounds having an ethylene oxide skeleton described therein, U.S. Pat. No. 7153632, japanese patent laid-open No. Hei 8-505958 3223223221, japanese patent laid-open No. 2007-291, and Japanese patent laid-open No. 2007-293 have hydrophilic groups described therein.

The structure of the polymerizable compound can be arbitrarily set, and details of the method of use such as the single use, the simultaneous use, and the amount of addition can be arbitrarily set.

The content of the polymerizable compound is preferably 5 to 75% by mass, more preferably 10 to 70% by mass, and still more preferably 15 to 60% by mass, based on the total mass of the image recording layer.

The content of the specific binder polymer is preferably more than 0% by mass and 400% by mass or less, more preferably 25% by mass to 300% by mass, and still more preferably 50% by mass to 200% by mass, based on the total mass of the polymerizable compounds in the image recording layer.

In the image recording layer, the specific binder polymer and the polymerizable compound preferably have a sea-island structure. For example, a structure in which the above-mentioned polymerizable compound is dispersed in islands (discontinuous layer) in the sea (continuous phase) of a specific binder polymer can be employed. It is considered that the sea-island structure is easily formed by setting the content of the specific binder polymer to the value within the above range with respect to the total mass of the polymerizable compound.

[ Polymer particles ]

The image recording layer preferably further contains polymer particles.

In the case where the image recording layer contains polymer particles, the polymer particles preferably contain polymer particles having a hydrophilic group from the viewpoint of UV brush resistance and on-press developability.

The hydrophilic group is not particularly limited as long as it has a hydrophilic structure, but examples thereof include an acid group such as a carboxyl group, a hydroxyl group, an amino group, a cyano group, a polyalkylene oxide structure, and the like.

The hydrophilic group is preferably a group having a polyalkylene oxide structure, a group having a polyester structure, or a sulfonic acid group, more preferably a group having a polyalkylene oxide structure or a sulfonic acid group, and still more preferably a group having a polyalkylene oxide structure, from the viewpoint of UV resistance and on-press developability.

The polyalkylene oxide structure is preferably a polyethylene oxide structure, a polypropylene oxide structure, or a poly (ethylene oxide/propylene oxide) structure from the viewpoint of on-site developability.

In addition, from the viewpoint of on-site developability, among the hydrophilic groups, the polyalkylene oxide structure preferably has a polypropylene oxide structure, and more preferably has a polyethylene oxide structure and a polypropylene oxide structure.

The number of the alkylene oxide structures in the above-mentioned polyalkylene oxide structure is preferably 2 or more, more preferably 5 or more, further preferably 5 to 200, and particularly preferably 8 to 150, from the viewpoint of on-site developability.

The polymer particles are preferably selected from the group consisting of thermoplastic polymer particles, thermally reactive polymer particles, polymer particles having a polymerizable group, microcapsules containing a hydrophobic compound, and microgels (crosslinked polymer particles). Among them, polymer particles or microgels having a polymerizable group are preferable. In a particularly preferred embodiment, the polymer particles comprise at least one ethylenically unsaturated polymerizable group. The presence of such polymer particles can provide an effect of improving the UV brushing resistance of exposed portions and the on-press developability of unexposed portions.

Also, the polymer particles are preferably thermoplastic polymer particles.

As the thermoplastic polymer particles, preferred are those described in, for example, the specifications of Research Disclosure No.33303, japanese patent application laid-open No. 9-123387, japanese patent application laid-open No. 9-131850, japanese patent application laid-open No. 9-171249, japanese patent application laid-open No. 9-171250, and European patent No. 931647, which are published in No. 1.1992.

Specific examples of the polymer constituting the thermoplastic polymer particles include homopolymers or copolymers of monomers such as ethylene, styrene, vinyl chloride, methyl acrylate, ethyl acrylate, methyl methacrylate, ethyl methacrylate, vinylidene chloride, acrylonitrile, vinylcarbazole, and an acrylate or methacrylate having a polyalkylene structure, and mixtures thereof. Preferred examples thereof include a copolymer comprising polystyrene, styrene and acrylonitrile, and polymethyl methacrylate. The thermoplastic polymer particles preferably have an average particle diameter of 0.01 to 3.0. Mu.m.

Examples of the thermally reactive polymer particles include polymer particles having a thermally reactive group. The thermally reactive polymer particles form a hydrophobic region by crosslinking based on a thermal reaction and a change in functional groups when the crosslinking is performed.

The thermally reactive group in the polymer particles having a thermally reactive group may be a functional group which can undergo any reaction as long as it can form a chemical bond, and is preferably a polymerizable group, and examples thereof include an ethylenically unsaturated group (for example, acryloyl group, methacryloyl group, vinyl group, allyl group, etc.) which undergoes a radical polymerization reaction, a cationically polymerizable group (for example, vinyl group, vinyloxy group, epoxy group, oxetanyl group, etc.), an isocyanate group which undergoes an addition reaction or a block thereof, an epoxy group, a vinyloxy group, a functional group having an active hydrogen atom to be a target of these reactions (for example, amino group, hydroxyl group, carboxyl group, etc.), a carboxyl group which undergoes a condensation reaction, a hydroxyl group or amino group to be a target of these reactions, an acid anhydride which undergoes a ring-opening addition reaction, an amino group or hydroxyl group to be a target of reactions, and the like.

As the microcapsules, at least a part of the components of the image recording layer is contained in the microcapsules, as described in, for example, japanese patent application laid-open nos. 2001-277740 and 2001-277742. The microcapsules may contain the constituent components of the image recording layer. A preferable embodiment of the microcapsule-containing image recording layer has a structure in which the microcapsules contain a hydrophobic component and the microcapsules contain a hydrophilic component.

The microgel (crosslinked polymer particles) can contain a part of the constituent components of the image recording layer on at least one of the surface or the inside thereof. In particular, from the viewpoint of image forming sensitivity and UV brushing resistance, a reactive microgel having a radical polymerizable group on the surface thereof is preferred.

In order to microencapsulate or microgel the constituent components of the image recording layer, a known method can be applied.

From the viewpoint of UV brushing resistance, stain resistance, and storage stability, the polymer particles are preferably obtained by reacting a polyhydric isocyanate compound which is an adduct of a polyhydric phenol compound having two or more hydroxyl groups in the molecule and isophorone diisocyanate with a compound having active hydrogen.

The polyphenol compound is preferably a compound containing a plurality of benzene rings having a phenolic hydroxyl group.

The compound having active hydrogen is preferably a polyol compound or a polyamine compound, more preferably a polyol compound, and still more preferably at least one compound selected from the group consisting of propylene glycol, glycerin, and trimethylolpropane.

The resin particles obtained by the reaction of the polyvalent isocyanate compound, which is an adduct of a polyvalent phenol compound having two or more hydroxyl groups in the molecule and isophorone diisocyanate, and the compound having active hydrogen include polymer particles described in paragraphs 0032 to 0095 of jp 2012-206495 a.

In addition, from the viewpoint of UV resistance and solvent resistance, the polymer particles preferably have a hydrophobic main chain, and include both i) a constituent unit having a cyano side group directly bonded to the hydrophobic main chain and ii) a constituent unit having a Pendant group (Pendant group) including a hydrophilic polyalkylene oxide segment.

The hydrophobic main chain preferably includes an acrylic resin chain.

Preferable examples of the cyano side group include- [ CH ] ₂ CH(C≡N)-]Or- [ CH ₂ C(CH ₃ )(C≡N)-]。

Further, the constituent unit having the cyano side group can be easily derived from an ethylenically unsaturated monomer, such as acrylonitrile or methacrylonitrile, or a combination thereof.

The alkylene oxide in the hydrophilic polyalkylene oxide segment is preferably ethylene oxide or propylene oxide, and more preferably ethylene oxide.

The number of repetition of the alkylene oxide structure in the hydrophilic polyalkylene oxide segment is preferably 10 to 100, more preferably 25 to 75, and still more preferably 40 to 50.

Particles of resins described in paragraphs 0039 to 0068 of jp 2008-503365 a are preferable examples of particles of a resin having a hydrophobic main chain and containing i) a constituent unit having a cyano side group directly bonded to the hydrophobic main chain and ii) a constituent unit having a side group containing a hydrophilic polyalkylene oxide segment.

The average particle diameter of the polymer particles is preferably 0.01 to 3.0. Mu.m, more preferably 0.03 to 2.0. Mu.m, and still more preferably 0.10 to 1.0. Mu.m. In this range, good resolution and stability over time can be obtained.

The average primary particle diameter of each particle in the present invention is measured by a light scattering method or an electron micrograph of the particle is taken, and the particle diameters of 5,000 particles in total are measured on the micrograph, and the average value is calculated. In addition, regarding the non-spherical particles, the particle diameter value of spherical particles having the same particle area as the particle area on the photograph is defined as the particle diameter.

Also, the average particle diameter in the present invention is a volume average particle diameter unless otherwise specified.

The content of the polymer particles is preferably 5 to 90% by mass with respect to the total mass of the image recording layer.

[ acid color developing agent

The image recording layer preferably contains an acid developer from the viewpoint of color developability.

The "acid developer" used in the present invention is a compound having a property of developing color by heating in a state of receiving an electron accepting compound (for example, a proton such as an acid). As the acid color developer, a colorless compound having a partial skeleton such as lactone, lactam, sultone, spiropyran, ester, amide, etc., and rapidly opening or cracking the partial skeleton when contacting with the electron-accepting compound is particularly preferable.

Examples of such acid-developing agents include 3,3-bis (4-dimethylaminophenyl) -6-dimethylaminophthalide (referred to as "crystal violet lactone"), 3,3-bis (4-dimethylaminophenyl) phthalide, 3- (4-dimethylaminophenyl) -3- (4-diethylamino-2-tolyl) -6-dimethylaminophthalide, 3- (4-dimethylaminophenyl) -3- (1,2-dimethylindol-3-yl) phthalide, 3- (4-dimethylaminophenyl) -3- (2-methylindol-3-yl) phthalide, 3,3-bis (1,2-dimethylindol-3-yl) -5-dimethylaminophthalide, 3,3-bis (1,2-dimethylindol-3-yl) -6-dimethylaminophthalide, 5329-bis (9-vinylcarbazole-3-yl) -6-dimethylaminophthalide 3257-bis (3-trifluoromethylindol-3-yl) -6-dimethylaminophthalide, 5329 zxft 3234-bis (3432 zxft 3234-dimethylaminophthalide-3-yl) -3-dimethyl-phthalide, 3-phthalide, and 3-bis (3482 zxft 3234-dimethyl-6-dimethyl-phthalide) -3-phthalide, 3,3-bis [1,1-bis (4-pyrrolidinophenyl) ethen-2-yl ] -4,5,6,7-tetrabromophthalide, 3,3-bis [1- (4-dimethylaminophenyl) -1- (4-methoxyphenyl) ethen-2-yl ] -4,5,6,7-tetrachlorophthalide lactone, 3,3-bis [1- (4-pyrrolidinophenyl) -1- (4-methoxyphenyl) ethen-2-yl ] -4,5,6,7-tetrachlorophthalide, 3- [1,1-bis (1-ethyl-2-methylindol-3-yl) ethen-2-yl ] -3- (4-diethylaminophenyl) phthalide, 3- [1,1-bis (1-ethyl-2-methylindol-3-yl) ethen-2-yl ] -3- (4-N-ethyl-N-phenyl) ethen-2-yl-phenyl lactone, 3- (4-N-ethoxyphenyl) ethen-2-yl ] -3- (4-diethylamino-phenyl) phthalide, 3- (4-N-octyl-2-methyl-indolyl) -3-methyl-3-yl ] -3- (4-N-ethyl-N-phenyl) ethenyl, 3-diethyl-aminophenyl) -lactone, and the like, 4,4-bis-dimethylaminobenzopropanol benzyl ether, N-halophenyl-leuco auramine (leuco-auramine), N-2,4,5-trichlorophenyl leuco auramine, rhodamine-B-anilinolactam, rhodamine- (4-nitrophenylamino) lactam, rhodamine-B- (4-chlorophenylamino) lactam, 3,7-bis (diethylamino) -10-benzoylphenoxazine, benzoyl leuco methylene blue, 4-nitrobenzoyl methylene blue, 3,6-dimethoxyfluorescein parent substance, 3-dimethylamino-7-methoxyfluorescein parent substance, 3-diethylamino-6-methoxyfluorescein parent substance, 3-diethylamino-7-methoxyfluorescein parent substance 3-diethylamino-7-chlorofluorescein precursor, 3-diethylamino-6-methyl-7-chlorofluorescein precursor, 3-diethylamino-6,7-dimethylfluorescein precursor, 3-N-hexyl-N-N-butylamino-7-methylfluorescein precursor, 3-diethylamino-7-dibenzylamine fluorescein precursor, 3-diethylamino-7-Xin An fluorescein precursor, 3-diethylamino-7-di-N-hexylamine fluorescein precursor, 3-diethylamino-7-phenylamino fluorescein precursor, 3-diethylamino-7- (2 '-fluoroanilino) fluorescein precursor, 3-diethylamino-7- (2' -chloroanilino) fluorescein Huang Muti, 3-diethylamino-7- (3 '-chlorophenylamino) fluorescein precursor, 3-diethylamino-7- (2', 3 '-dichlorophenylamino) fluorescin precursor, 3-diethylamino-7- (3' -trifluoromethylphenylamino) fluorescin precursor, 3-di-N-butylamino-7- (2 '-fluoroanilino) fluorescin precursor, 3-di-N-butylamino-7- (2' -chloroanilino) fluorescin precursor, 3-N-isoamyl-N-ethylamino-7- (2 '-chloroanilino) fluorescin precursor, 3-N-N-hexyl-N-ethylamino-7- (2' -chloroanilino) fluorescin precursor, 3-diethylamino-6-chloro-7-anilinofluorin precursor, 3-di-N-butylamino-6-chloro-7-anilinofluorin precursor, 3-diethylamino-6-methoxy-7-anilinofluorin precursor, 3-di-N-butylamino-6-ethoxy-7-anilinofluorin precursor, 3-pyrrolidinyl-6-methyl-7-anilinofluorin precursor, 3-piperidinyl-6-methyl-7-anilinofluorin precursor, 3-morpholinyl-6-methyl-7-anilinofluorin precursor, 8978-methyl-6-anilinofluorin precursor, 3-dimethylamino-6-methyl-7-phenylamino fluorescein precursor, 3-diethylamino-6-methyl-7-phenylamino fluorescein precursor, 3-di-N-butylamino-6-methyl-7-phenylamino fluorescein precursor, 3-di-N-pentylamino-6-methyl-7-phenylamino fluorescein precursor, and a mixture of the precursors 3-N-ethyl-N-methylamino-6-methyl-7-anilinofluoran precursor, 3-N-N-propyl-N-ethylamino-6-methyl-7-anilinofluoran precursor, and mixtures thereof 3-N-N-butyl-N-methylamino-6-methyl-7-phenylamino fluorescein precursor, 3-N-N-butyl-N-ethylamino-6-methyl-7-phenylamino fluorescein precursor, 3-N-isobutyl-N-methylamino-6-methyl-7-phenylamino fluorescein precursor, 3-N-isobutyl-N-ethylamino-6-methyl-7-phenylamino fluorescein precursor, 3-N-isopentyl-N-ethylamino-6-methyl-7-phenylamino fluorescein precursor, 3-N-N-hexyl-N-methylamino-6-methyl-7-phenylamino fluorescein Huang Muti, 3-N-cyclohexyl-N-ethylamino-6-methyl-7-anilinofluorine precursor, 3-N-cyclohexyl-N-N-propylamino-6-methyl-7-anilinofluorine precursor, 3-N-cyclohexyl-N-N-butyl-6-methyl-7-anilinofluorine precursor, 3-N-cyclohexyl-N-hexylamino-6-methyl-7-anilinofluorine precursor, 3-N-cyclohexyl-N-N-octylamino-6-methyl-7-anilinofluorine precursor, 3-N- (2 '-methoxyethyl) -N-methylamino-6-methyl-7-anilinofluorine precursor, 3-N- (2' -methoxyethyl) -N-ethylamino-6-methyl-7-phenylamino fluorescein parent substance, 3-N- (2 '-methoxyethyl) -N-isobutylamino-6-methyl-7-phenylamino fluorescein parent substance, 3-N- (2' -ethoxyethyl) -N-methylamino-6-methyl-7-phenylamino fluorescein parent substance, 3-N- (2 '-ethoxyethyl) -N-ethylamino-6-methyl-7-phenylamino fluorescein parent substance, 3-N- (3' -methoxypropyl) -N-methylamino-6-methylamino-methyl The fluorescent yellow precursor of phenyl-7-aniline, 3-N- (3 '-methoxypropyl) -N-ethylamino-6-methyl-7-aniline, 3-N- (3' -ethoxypropyl) -N-methylamino-6-methyl-7-aniline, 3-N- (3 '-ethoxypropyl) -N-ethylamino-6-methyl-7-aniline, 3-N- (2' -tetrahydrofurfuryl) -N-ethylamino-6-methyl-7-aniline, 3-N- (4 '-tolyl) -N-ethylamino-6-methyl-7-aniline, 3-diethylamino-6-ethyl-7-aniline, 3-diethylamino-6-methyl-7- (3' -toluidino) p-luoro, 3-diethylamino-6-methyl-7- (2 ',6' -xylidino) p-luoro, 3-di-N-butylamino-6-methyl-7- (2 ',6' -dimethylamino) p-luoro, 3-N-butylamino-6-methyl-7- (2 ',6' -dimethylamino) p-fluorophenyl, 3 '-bis [ 3' -dimethylamino-6-methyl-7 '-dimethylamino ] p-3238' - (3 '-dimethylamino) p-3262' -cyclohexyl-t-dimethylamino) p-3238, and the like 6-MethylFluorochromene Huang Muti) -7-ylaminophenyl ] propane, fluorescein precursors such as 3- [4'- (4-phenylaminophenyl) aminophenyl ] amino-6-methyl-7-chlorofluorescein precursor, 3- [4' - (dimethylaminophenyl) ] amino-5,7-dimethylfluoroglucuronide Huang Muti, 3- (2-methyl-4-diethylaminophenyl) -3- (1-ethyl-2-methylindol-3-yl) -4-azaphthalein, 3- (2-n-propoxycarbonylamino-4-di-n-propylaminophenyl) -3- (1-ethyl-2-methylindol-3-yl) -4-azaphthalein, 3- (2-methylamino-4-di-n-propylaminophenyl) -3- (1-ethyl-2-methylindol-3-yl) -4-azaphthalein, 3- (2-methyl-4-di-n-hexylaminophenyl) -3- (1-n-octyl-2-methylindol) -3-yl) -4-azaphthalein, 3- (2-methyl-4-di-n-hexylaminophenyl) -3- (1-octyl-3-methyl-indolyl) -3525-bis (3-octylphthalein) -3526, 3-ethoxyphthalein, 3-4-bis (3-octylphthalein) -3526, 3- (2-ethoxy-4-diethylaminophenyl) -3- (1-ethyl-2-methylindol-3-yl) -4-azaphthalein lactone, 3- (2-ethoxy-4-diethylaminophenyl) -3- (1-octyl-2-methylindol-3-yl) -4 or 7-azaphthalein lactone, 3- (2-ethoxy-4-diethylaminophenyl) -3- (1-ethyl-2-methylindol-3-yl) -4 or 7-azaphthalein lactone, 3- (2-hexyloxy-4-diethylaminophenyl) -3- (1-ethyl-2-methylindol-3-yl) -4 or 7-azaphthalein lactone, 3- (2-ethoxy-4-diethylaminophenyl) -3- (1-ethyl-2-phenylindol-3-yl) -4 or 7-azaphthalein lactone, 3- (2-butoxy-4-diethylaminophenyl) -3- (1-ethyl-2-phenylindol-3-yl) -4 or 7-azaphthalein lactone, 3-methyl-spiro-3-diazanaphthalein, 3-spiro-3-spiropyrane, spiropyrane-3-spiropyrane, spirol-3-e, spiropyrane, spirol-e, spirol-3, spirol-e, spiropyrane, and spirol-e, phthalides such as 3-benzyl-spiro-dinaphthopyran, 3-methyl-naphtho- (3-methoxybenzo) spiropyran, 3-propyl-spiro-dibenzopyran-3,6-bis (dimethylamino) fluorene-9-spiro-3 ' - (6 ' -dimethylamino) phthalide, 3,6-bis (diethylamino) fluorene-9-spiro-3 ' - (6 ' -dimethylamino) phthalide, and 2' -phenylamino-6 ' - (N-ethyl-N-isoamyl) amino-3 ' -methylspiro [ isobenzofuran-1 (3H), 9' - (9H) xanthene ] -3-one, 2' -phenylamino-6 ' - (N-ethyl-N- (4-tolyl)) amino-3 ' -methylspiro [ isobenzofuran-1 (3H), 9' - (9H) xanthene ] -3-one, 3' -N, N-dibenzylamino-6 ' -N, N-diethylamino [1 (4-tolyl)) amino-3 ' -methylspiro [ isobenzofuran-1 (3H), 9' - (9H) xanthene ] -3-one, 3' -N, N-dibenzylamino-6 ' -diethylamino [1- (4-tolyl)) amino-1 (3H), and 2' - (4-methylphenyl) spirol) phthalide, 9' - (9H) xanthen ] -3-one, and the like.

Among them, the acid color developer used in the present invention is preferably at least one compound selected from the group consisting of a spiropyran compound, a spirooxazine compound, a spirolactone compound, and a spirolactam compound, from the viewpoint of color developability.

The color of the colored pigment is preferably green, blue or black from the viewpoint of visibility.

As the acid developer, commercially available products can be used, such as ETAC, RED500, RED520, CVL, S-205, BLACK305, BLACK400, BLACK100, BLACK500, H-7001, GREEN300, NIRBLACK78, BLUE220, H-3035, BLUE203, ATP, H-1046, H-2114 (Fukui Yamada Chemical Co., ltd.), ORANGE-DCF, vermilion-DCF, PINK-DCF, RED-DCF, BLMB, CVL, GREEN-DCF, TH-107 (HODOGAYA CHEMICAL CO., LTD. Manufactured), ODB-2, ODB-4, ODB-250, ODB-BlackV, BLUE-63, BLUE-502, GRGN-2, green-118, green-40, red-8, red Chemical Co., manufactured by Tokyo, and so on. Among these commercially available products, ETAC, S-205, BLACK305, BLACK400, BLACK100, BLACK500, H-7001, GREEN300, NIRBLACK78, H-3035, ATP, H-1046, H-2114, GREEN-DCF, blue-63, GN-169, and crystal violet lactone are preferable because the visible light absorption of the film is good.

These acid color developers may be used alone or in combination of two or more.

The content of the acid developer is preferably 0.5 to 10% by mass, and more preferably 1 to 5% by mass, based on the total mass of the image recording layer.

[ adhesive polymers other than the specific adhesive polymer ]

The image recording layer may contain a binder polymer other than the specific binder polymer (hereinafter, also referred to as "other binder polymer").

The specific binder polymer and the polymer corresponding to the polymer particles do not correspond to the other binder polymers. That is, the other binder polymer is a polymer that does not have a structural unit formed of a styrene compound and is not in a particle shape.

As the other binder polymer, a (meth) acrylic resin, a polyvinyl acetal resin, or a polyurethane resin is preferable.

Among them, the other binder polymer can be preferably used a known binder polymer used in the image recording layer of the lithographic printing plate precursor. As an example, a binder polymer used for an on-press development type lithographic printing plate precursor (hereinafter, also referred to as "on-press development binder polymer") is described in detail.

The on-press developing binder polymer is preferably a binder polymer having an alkylene oxide chain. The adhesive polymer having an alkylene oxide chain may have a poly (alkylene oxide) site in the main chain or a poly (alkylene oxide) site in the side chain. The graft polymer may have a poly (alkylene oxide) in a side chain, or may be a block copolymer of a block material composed of a repeating unit containing a poly (alkylene oxide) and a block material composed of a repeating unit containing no (alkylene oxide).

In the case where the main chain has a poly (alkylene oxide) site, a polyurethane resin is preferable. Examples of the main chain polymer in the case where the side chain has a poly (alkylene oxide) moiety include (meth) acrylic resins, polyvinyl acetal resins, polyurethane resins, polyurea-aldehyde resins, polyimide resins, polyamide resins, epoxy resins, polystyrene resins, phenol novolac resins, polyester resins, synthetic rubbers, and natural rubbers, and (meth) acrylic resins are particularly preferable.

Another preferable example of the other binder polymer is a polymer compound (hereinafter, also referred to as a star polymer compound) having a core of a polyfunctional thiol having 6 to 10 functions and bonded to the core via a thioether bond to form a polymer chain having a polymerizable group. As the star polymer compound, for example, a compound described in japanese unexamined patent publication No. 2012-148555 can be preferably used.

As described in jp 2008-195018 a, a star polymer compound has a polymerizable group such as an ethylenically unsaturated bond in a main chain or a side chain (preferably a side chain) for improving the strength of a coating film in an image portion. Crosslinking is formed between polymer molecules by the polymerizable group, and curing is promoted.

The polymerizable group is preferably an ethylenically unsaturated group such as a (meth) acrylic group, a vinyl group, an allyl group, or a vinylphenyl (styryl) group, or an epoxy group, and from the viewpoint of polymerization reactivity, a (meth) acrylic group, a vinyl group, and a vinylphenyl (styryl) group are more preferable, and a (meth) acrylic group is particularly preferable. These groups can be introduced into the polymer by a high molecular reaction and copolymerization. For example, a reaction of a polymer having a carboxyl group in a side chain thereof with glycidyl methacrylate or a reaction of a polymer having an epoxy group with an ethylenically unsaturated group-containing carboxylic acid such as methacrylic acid can be used. These groups may be used simultaneously.

The molecular weight of the binder polymer is preferably 2,000 or more, more preferably 5,000 or more, and still more preferably 10,000 to 300,000 in terms of polystyrene by GPC.

If necessary, a hydrophilic polymer such as polyacrylic acid or polyvinyl alcohol described in jp 2008-195018 a can be used in combination. Further, the lipophilic polymer and the hydrophilic polymer can be used simultaneously.

In the image recording layer used in the present invention, one kind of other binder polymer may be used alone, or two or more kinds may be used simultaneously.

The other binder polymer may be contained in any amount in the image recording layer, but the content of the binder polymer is preferably 1 to 90% by mass, and more preferably 5 to 80% by mass, with respect to the total mass of the image recording layer.

When the image recording layer of the present invention contains another binder polymer, the content of the other binder polymer is preferably more than 0% by mass and 99% by mass or less, more preferably 20% by mass to 95% by mass, and still more preferably 40% by mass to 90% by mass based on the total mass of the specific binder polymer and the other binder polymer.

The content of the other binder polymer in the image recording layer is preferably smaller than the content of the specific binder polymer.

[ chain transfer agent ]

The image recording layer may contain a chain transfer agent. Chain transfer agents help to improve UV brush resistance in lithographic printing plates.

The chain transfer agent is preferably a thiol compound, more preferably a thiol compound having 7 or more carbon atoms, and still more preferably a compound having a mercapto group on an aromatic ring (aromatic thiol compound), from the viewpoint of a boiling point (low volatility). The thiol compound is preferably a monofunctional thiol compound.

Specific examples of the chain transfer agent include the following compounds.

[ chemical formula 51]

[ chemical formula 52]

[ chemical formula 53]

[ chemical formula 54]

The chain transfer agent may be added in one kind alone, or two or more kinds may be used simultaneously.

The content of the chain transfer agent is preferably 0.01 to 50% by mass, more preferably 0.05 to 40% by mass, and still more preferably 0.1 to 30% by mass, based on the total mass of the image recording layer.

[ Lipidating agent ]

The image recording layer may contain a sensitizing agent such as a phosphonium compound, a nitrogen-containing low molecular weight compound, or an ammonium group-containing polymer for improving the ink-applying property. In particular, when the overcoat layer contains an inorganic layered compound, these compounds function as a surface covering agent for the inorganic layered compound, and thus a decrease in the ink adhesion during printing with the inorganic layered compound can be suppressed.

The fat-sensitive agent is preferably a combination of a phosphonium compound, a nitrogen-containing low-molecular-weight compound and an ammonium group-containing polymer, and more preferably a combination of a phosphonium compound, a quaternary ammonium salt and an ammonium group-containing polymer.

Phosphonium compounds

Examples of the phosphonium compound include those described in Japanese patent laid-open Nos. 2006-297907 and 2007-050660. Specific examples thereof include tetrabutylphosphonium iodide, butyltriphenylphosphonium bromide, tetraphenylphosphonium bromide, 1,4-bis (triphenylphosphonium) butane = bis (hexafluorophosphate), 1,7-bis (triphenylphosphonium) heptane = sulfate, 1,9-bis (triphenylphosphonium) nonane = naphthalene-2,7-disulfonate, and the like.

Nitrogen-containing low molecular weight compounds

Examples of the nitrogen-containing low-molecular-weight compound include amine salts and quaternary ammonium salts. Furthermore, imidazolium salts, benzimidazolium salts, pyridinium salts, and quinolinium salts may be mentioned. Among them, quaternary ammonium salts and pyridinium salts are preferable. Specific examples thereof include tetramethylammonium = hexafluorophosphate, tetrabutylammonium = hexafluorophosphate, dodecyltrimethylammonium = p-toluenesulfonate, benzyltriethylammonium = hexafluorophosphate, benzyldimethyloctylammonium = hexafluorophosphate, benzyldimethyldodecylammonium = hexafluorophosphate, compounds described in paragraphs 0021 to 0037 of jp-a-2008-284858, and compounds described in paragraphs 0030 to 0057 of jp-a-2009-090645.

Polymers containing ammonium groups

The ammonium group-containing polymer may have an ammonium group in the structure, and is preferably a polymer containing 5 to 80mol% of a (meth) acrylate having an ammonium group in a side chain as a copolymerization component. Specific examples thereof include polymers described in paragraphs 0089 to 0105 of Japanese patent application laid-open No. 2009-208458.

The ammonium salt-containing polymer is preferably a polymer having a reduced viscosity (unit: ml/g) value in the range of 5 to 120, more preferably in the range of 10 to 110, and particularly preferably in the range of 15 to 100, which is determined by the measurement method described in jp 2009-208458 a. When the reduced viscosity is converted into a weight average molecular weight (Mw), it is preferably 10,000 to 150,000, more preferably 17,000 to 140,000, and particularly preferably 20,000 to 130,000.

Specific examples of the ammonium group-containing polymer are shown below.

(1) 2- (trimethylammonium) ethylmethacrylate = p-toluenesulfonate/3,6-dioxaheptyl methacrylate copolymer (molar ratio 10/90, mw4.5 ten thousand)

(2) 2- (trimethylammonium) ethyl methacrylate = hexafluorophosphate/3,6-dioxaheptyl methacrylate copolymer (molar ratio 20/80, mw6.0 ten thousand)

(3) 2- (ethyldimethylammonio) ethylmethacrylate = p-toluenesulfonate/hexyl methacrylate copolymer (molar ratio 30/70, mw4.5 ten thousand)

(4) 2- (trimethylammonium) ethyl methacrylate = hexafluorophosphate/2-ethylhexyl methacrylate copolymer (molar ratio 20/80, mw6.0 ten thousand)

(5) 2- (trimethylammonium) ethyl methacrylate = methyl sulfate/hexyl methacrylate copolymer (molar ratio 40/60, mw7.0 ten thousand)

(6) 2- (butyldimethylammonio) ethylmethacrylate = hexafluorophosphate/3,6-dioxaheptyl methacrylate copolymer (molar ratio 25/75, mw6.5 ten thousand)

(7) 2- (butyldimethylammonio) ethylacrylate = hexafluorophosphate/3,6-dioxaheptyl methacrylate copolymer (molar ratio 20/80, mw6.5 ten thousand)

(8) 2- (butyldimethylammonio) ethylmethacrylate = 13-ethyl-5,8, 11-trioxa-1-heptadecanesulfonate/3,6-dioxaheptyl methacrylate copolymer (molar ratio 20/80, mw7.5 ten thousand)

The fat-sensitive agent may be added in one kind or two or more kinds may be used simultaneously.

The content of the fat-sensitive agent is preferably 1 to 40.0 mass%, more preferably 2 to 25.0 mass%, and still more preferably 3 to 20 mass% with respect to the total mass of the image recording layer.

[ development accelerator ]

The image recording layer used in the present invention may contain a development accelerator.

The development accelerator is preferably a hydrophilic high molecular compound or a hydrophilic low molecular compound.

In the present invention, the hydrophilic high molecular compound means a compound having a molecular weight (weight average molecular weight in the case of having a molecular weight distribution) of 3,000 or more, and the hydrophilic low molecular compound means a compound having a molecular weight (weight average molecular weight in the case of having a molecular weight distribution) of less than 3,000.

Hydrophilic polymer compounds

Examples of the hydrophilic polymer compound include a cellulose compound and polyvinyl alcohol, and a cellulose compound is preferable.

The cellulose compound includes cellulose and a compound in which at least a part of cellulose is modified (modified cellulose compound), and preferably a modified cellulose compound.

The modified cellulose compound is preferably a compound in which at least a part of the hydroxyl groups of cellulose is substituted with at least one member selected from the group consisting of alkyl groups and hydroxyalkyl groups.

The modified cellulose compound is preferably an alkyl cellulose compound or a hydroxyalkyl cellulose compound, and more preferably a hydroxyalkyl cellulose compound.

As the alkyl cellulose compound, methyl cellulose can be preferably mentioned.

Preferred examples of the hydroxyalkyl cellulose compound include hydroxypropyl cellulose.

The molecular weight (weight average molecular weight in the case of having a molecular weight distribution) of the hydrophilic polymer compound is preferably 3,000 to 300,000, more preferably 10,000 to 150,000.

Hydrophilic low molecular weight compounds

Examples of the hydrophilic low-molecular compound include an ethylene glycol compound, a polyol compound, an organic amine compound, an organic sulfonic acid compound, an organic sulfamic acid compound, an organic sulfuric acid compound, an organic phosphonic acid compound, an organic carboxylic acid compound, and a betaine compound, and the polyol compound, the organic sulfonic acid compound, and the betaine compound are preferable.

Examples of the ethylene glycol compound include ethylene glycols such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, and tripropylene glycol, and ether or ester derivatives of these compounds.

Examples of the polyol compound include glycerol, pentaerythritol, and tris (2-hydroxyethyl) isocyanurate.

Examples of the organic amine compound include triethanolamine, diethanolamine, monoethanolamine and salts thereof.

Examples of the organic sulfonic acid compound include alkylsulfonic acid, toluenesulfonic acid, benzenesulfonic acid and the like, and salts thereof, and preferable examples thereof include alkylsulfonic acids having an alkyl group having 8 to 20 carbon atoms.

Examples of the organic sulfamic acid compound include alkylaminosulfonic acids and salts thereof.

Examples of the organic sulfuric acid compound include alkyl sulfuric acid, alkyl ether sulfuric acid, and salts thereof.

Examples of the organic phosphonic acid compound include phenylphosphonic acid and salts thereof.

Examples of the organic carboxylic acid compound include tartaric acid, oxalic acid, citric acid, malic acid, lactic acid, gluconic acid, and salts thereof.

Examples of the betaine compound include phosphobetaine compounds, sulfobetaine compounds, carboxybetaine compounds, and the like, and trimethylglycine is preferable.

The molecular weight (weight average molecular weight in the case of having a molecular weight distribution) of the hydrophilic low-molecular compound is preferably 50 or more and less than 3,000, more preferably 100 to 1,000.

Content-

The developing accelerator may be added alone or in combination of two or more.

The content of the development accelerator is preferably 0.1% by mass or more and 20% by mass or less, more preferably 0.5% by mass or more and 15% by mass or less, and still more preferably 1% by mass or more and 10% by mass or less, relative to the total mass of the image recording layer.

[ other Components ]

As other components, the image recording layer can contain a surfactant, a polymerization inhibitor, a higher fatty acid derivative, a plasticizer, inorganic particles, an inorganic layered compound, and the like. Specifically, reference can be made to the descriptions of paragraphs 0114 to 0159 of japanese patent application laid-open No. 2008-284817.

[ formation of image recording layer ]

The image recording layer in the lithographic printing plate precursor according to the present invention can be formed by, for example, preparing a coating solution by dispersing or dissolving the above-mentioned necessary components in a known solvent, coating the coating solution on a support by a known method such as bar coater coating, and drying the coating solution, as described in paragraphs 0142 to 0143 of jp 2008-195018 a. The amount of the image recording layer (solid content) after coating and drying is preferably 0.3g/m, although it varies depending on the application ² ～3.0g/m ² . Within this range, good results can be obtainedGood sensitivity and good film-coating properties of the image recording layer.

As the solvent, a known solvent can be used. Specific examples of the organic solvent include water, acetone, methyl ethyl ketone (2-butanone), cyclohexane, ethyl acetate, dichloroethane, tetrahydrofuran, toluene, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol dimethyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, acetylacetone, cyclohexanone, diacetone alcohol, ethylene glycol monomethyl ether acetate, ethylene glycol ethyl ether acetate, ethylene glycol monoisopropyl ether, ethylene glycol monobutyl ether acetate, 1-methoxy-2-propanol, 3-methoxy-1-propanol, methoxymethoxyethanol, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, 3-methoxypropyl acetate, N-dimethylformamide, dimethyl sulfoxide, γ -butyrolactone, methyl lactate, and ethyl lactate. One solvent may be used alone, or two or more solvents may be used simultaneously. The solid content concentration in the coating liquid is preferably 1 to 50% by mass.

The amount of the image recording layer (solid content) applied after coating and drying varies depending on the application, but is preferably 0.3g/m from the viewpoint of obtaining good sensitivity and good film properties of the image recording layer ² ～3.0g/m ² 。

The film thickness of the image recording layer in the lithographic printing plate precursor according to the present invention is preferably 0.1 to 3.0. Mu.m, and more preferably 0.3 to 2.0. Mu.m.

In the present invention, regarding the film thickness of each layer in the lithographic printing plate precursor, a slice obtained by cutting the surface of the lithographic printing plate precursor in the vertical direction is prepared, and the cross section of the slice is observed by a scanning microscope (SEM) to confirm the film thickness.

< outer coating >

The lithographic printing plate precursor according to the present invention preferably has an overcoat layer (sometimes referred to as a "protective layer") on the surface of the image-recording layer on the side opposite to the support side.

The thickness of the overcoat layer is preferably larger than the thickness of the image recording layer.

In addition to the effect of inhibiting the image formation inhibition reaction by oxygen blocking, the overcoat layer also has a function of preventing scratches from being generated in the image recording layer and a function of preventing ablation from being generated during exposure to high-illuminance laser light.

The overcoat layer having such properties is described in, for example, U.S. Pat. No.3,458,311 and Japanese patent publication No. 55-049729. The low oxygen permeability polymer used in the overcoat layer may be selected and used as appropriate from either a water-soluble polymer or a water-insoluble polymer, or two or more kinds may be used in combination as necessary.

In the present invention, the water-soluble polymer means a polymer which does not precipitate even when 1g or more of the polymer is dissolved in 100g of pure water at 70 ℃ and 1g of the polymer is dissolved in 100g of pure water at 70 ℃ and the resulting solution is cooled to 25 ℃.

Examples of the water-soluble polymer used in the overcoat layer include polyvinyl alcohol, modified polyvinyl alcohol, polyvinyl pyrrolidone, water-soluble cellulose derivatives, polyethylene glycol, and poly (meth) acrylonitrile.

As the modified polyvinyl alcohol, an acid-modified polyvinyl alcohol having a carboxyl group or a sulfo group can be preferably used. Specifically, modified polyvinyl alcohols described in Japanese patent application laid-open Nos. 2005-250216 and 2006-259137 are mentioned.

The water-soluble polymer preferably contains polyvinyl alcohol, and more preferably contains polyvinyl alcohol having a saponification degree of 50% or more.

The saponification degree is preferably 60% or more, more preferably 70% or more, and still more preferably 85% or more. The upper limit of the saponification degree is not particularly limited, and may be 100% or less.

The saponification degree described above was measured according to JIS K6726: 1994, to be used as a reagent.

Further, as an embodiment of the overcoat layer, an embodiment including polyvinyl alcohol and polyethylene glycol can be preferably cited.

In the case where the overcoat layer in the present invention contains a water-soluble polymer, the content of the water-soluble polymer is preferably 1 to 99 mass%, more preferably 3 to 97 mass%, and still more preferably 5 to 95 mass% with respect to the total mass of the overcoat layer.

The overcoat layer may contain an inorganic layered compound in order to improve oxygen barrier properties. The inorganic layered compound is a particle having a thin flat plate-like shape, and examples thereof include mica groups such as natural mica and synthetic mica, and a particle having a formula: 3 MgO.4 SiO.H ₂ Talc represented by O, taeniolite, montmorillonite, saponite, hectorite, zirconium phosphate, and the like.

The inorganic lamellar compound preferably used is a mica compound. Examples of the mica compound include: a (B, C) _2-5 D ₄ O ₁₀ (OH,F,O) ₂ [ wherein A is any one of K, na and Ca, B and C are any one of Fe (II), fe (III), mn, al, mg and V, and D is Si or Al.]The mica group such as natural mica and synthetic mica.

In the mica group, examples of natural mica include muscovite, paragonite, phlogopite, biotite, and lepidolite. Examples of the synthetic mica include fluorophlogopite KMg ₃ (AlSi ₃ O ₁₀ )F ₂ Potassium tetrasilicic mica KMg _2.5 (Si ₄ O ₁₀ )F ₂ Iso-nonswelling mica and Na tetrafluoro silicon mica NaMg _2.5 (Si ₄ O ₁₀ )F ₂ Na or Li with mica (Na, li) Mg ₂ Li(Si ₄ O ₁₀ )F ₂ Montmorillonite series Na or Li hectorite (Na, li) _1/8 Mg _2/5 Li _1/8 (Si ₄ O ₁₀ )F ₂ And swelling mica. Also synthetic smectites are useful.

Among the mica compounds, fluorine-based swellable mica is particularly useful. That is, the swelling synthetic mica has a thickness of

The metal atom substitution in the lattice of the laminated structure composed of the left and right unit lattice layers is significantly larger than that of other clay minerals. As a result, a shortage of positive charge occurs in the lattice layer, and Li is adsorbed between the layers to compensate for the shortage ⁺ 、Na ⁺ 、Ca ²⁺ 、Mg ²⁺ And the like. These cations interposed between the layers are called exchangeable cations, and can be obtained by exchanging with a plurality of kinds of cations. In particular, the cation between the layers is Li ⁺ 、Na ⁺ In the case of (2), the bonding between the lamellar lattices is weak because the ionic radius is small, and the swelling is large by water. When a shear force is applied in this state, the layered crystal lattice is easily broken to form a stable sol in water. This tendency of the swellable synthetic mica is strong, and thus it is particularly preferably used.

The shape of the mica compound is preferably as thin as possible from the viewpoint of diffusion control, and the larger the plane size is, the better the smoothness of the coated surface and the transparency of the active light ray are not hindered. Accordingly, the aspect ratio is preferably 20 or more, more preferably 100 or more, and particularly preferably 200 or more. The aspect ratio is a ratio of the length to the thickness of the particle, and can be measured, for example, by a projection view obtained from a photomicrograph of the particle. The larger the aspect ratio, the greater the effect obtained.

The average major axis of the particle diameter of the mica compound is preferably 0.3 to 20 μm, more preferably 0.5 to 10 μm, and particularly preferably 1 to 5 μm. The average thickness of the particles is preferably 0.1 μm or less, more preferably 0.05 μm or less, and particularly preferably 0.01 μm or less. Specifically, for example, in the case of swellable synthetic mica, which is a typical compound, the thickness is preferably about 1nm to 50nm and the planar size (major axis) is preferably about 1 μm to 20 μm.

The content of the inorganic layered compound is preferably 1 to 60% by mass, more preferably 3 to 50% by mass, based on the total solid content of the overcoat layer. When a plurality of inorganic layered compounds are used simultaneously, the total amount of the inorganic layered compounds is also preferably the above amount. Within the above range, the oxygen barrier property is improved and good sensitivity can be obtained. Further, the ink adhesion can be prevented from being lowered.

The overcoat layer may contain known additives such as a plasticizer for imparting flexibility, a surfactant for improving coatability, and inorganic particles for controlling surface lubricity. The overcoat layer may contain a sensitizer described in the image recording layer.

The overcoat layer is applied by a known method. The coating amount (solid content) of the overcoat layer is preferably 0.01g/m ² ～10g/m ² More preferably 0.02g/m ² ～3g/m ² Particularly preferably 0.02g/m ² ～1g/m ² 。

The thickness of the overcoat layer in the lithographic printing plate precursor according to the present invention is preferably 0.1 to 5.0. Mu.m, and more preferably 0.3 to 4.0. Mu.m.

The thickness of the overcoat layer in the lithographic printing plate precursor according to the present invention is preferably 1.1 to 5.0 times, and more preferably 1.5 to 3.0 times the thickness of the image recording layer.

< undercoat layer >

In the lithographic printing plate precursor according to the present invention, an undercoat layer (also referred to as an intermediate layer in some cases) is preferably provided between the image recording layer and the support. The undercoat layer enhances adhesion between the support and the image recording layer in the exposed portion, and facilitates peeling of the image recording layer from the support in the unexposed portion, and therefore, the undercoat layer contributes to improvement of developability while suppressing a decrease in UV resistance. In addition, in the case of infrared laser exposure, the undercoat layer functions as a heat-insulating layer, and thus has an effect of preventing the heat generated by exposure from diffusing to the support and decreasing the sensitivity.

Examples of the compound used for the undercoat layer include polymers having adsorptive groups and hydrophilic groups that can be adsorbed on the surface of the support. In order to improve the adhesion to the image recording layer, a polymer having an adsorptive group and a hydrophilic group and further having a crosslinkable group is preferable. The compound used in the undercoat layer may be a low molecular compound or a polymer. Two or more compounds used for the undercoat layer may be mixed and used as necessary.

When the compound used in the undercoat layer is a polymer, a copolymer of a monomer having an adsorptive group, a monomer having a hydrophilic group, and a monomer having a crosslinkable group is preferable.

As the adsorptive group which can be adsorbed on the surface of the support, preferred are a phenolic hydroxyl group, a carboxyl group and-PO ₃ H ₂ 、-OPO ₃ H ₂ 、-CONHSO ₂ -、-SO ₂ NHSO ₂ -、-COCH ₂ COCH ₃ . As the hydrophilic group, sulfo group or a salt thereof, or a salt of carboxyl group is preferable. The crosslinkable group is preferably an acryloyloxy group, a methacryloyloxy group, an acrylamido group, a methacrylamido group, an allyl group or the like.

The polymer may have a crosslinkable group introduced by forming a salt with a polar substituent of the polymer, a substituent having a charge opposite to that of the polar substituent, and a compound having an ethylenically unsaturated bond, and the polymer may have a monomer other than the above-mentioned monomers, preferably a hydrophilic monomer, copolymerized therein.

Specifically, a silane coupling agent having an addition polymerizable ethylenic double bond reactive group described in Japanese patent application laid-open No. H10-282679 and a phosphorus compound having an ethylenic double bond reactive group described in Japanese patent application laid-open No. H2-304441 are preferable. It is also preferable to use a low-molecular or high-molecular compound having a crosslinkable group (preferably an ethylenically unsaturated bond group), a functional group that interacts with the surface of the support, and a hydrophilic group, which are described in each of Japanese patent application laid-open Nos. 2005-238816, 2005-125749, 2006-239867, and 2006-215263.

More preferred examples of the compound include high molecular polymers having an adsorptive group, a hydrophilic group and a crosslinkable group, which are capable of being adsorbed on the surface of a support, as described in Japanese patent laid-open Nos. 2005-125749 and 2006-188038.

The content of the ethylenically unsaturated bond group in the polymer used in the undercoat layer is preferably 0.1 to 10.0mmol, more preferably 0.2 to 5.5mmol, per 1g of the polymer.

The weight average molecular weight (Mw) of the polymer used in the undercoat layer is preferably 5,000 or more, and more preferably 1 to 30 ten thousand.

The undercoat layer may contain, in addition to the compound for undercoat layer, a chelating agent, a secondary or tertiary amine, a polymerization inhibitor, a compound having an amino group or a functional group having a polymerization inhibiting ability and a group that interacts with the surface of the aluminum support (for example, 1,4-diazabicyclo [2.2.2] octane (DABCO), 2,3,5,6-tetrahydroxy-p-benzoquinone, chloranil, sulfophthalic acid, hydroxyethylethylenediaminetriacetic acid, dihydroxyethylethylenediaminediacetic acid, hydroxyethyliminodiacetic acid, and the like), and the like, in order to prevent contamination with time.

The undercoat layer is applied by a known method. The amount of the primer coating (solid content) is preferably 0.1mg/m ² ～100mg/m ² More preferably 1mg/m ² ～30mg/m ² 。

(method of manufacturing planographic printing plate and planographic printing method)

The lithographic printing plate precursor of the present invention can be subjected to image exposure and development treatment to produce a lithographic printing plate.

The method for producing a lithographic printing plate according to the present invention preferably includes: a step of exposing the lithographic printing plate precursor according to the present invention to light in an image form (hereinafter, also referred to as "exposure step"); and a step of supplying at least one selected from the group consisting of printing ink and fountain solution to the printing press to remove the image recording layer of the non-image portion (hereinafter, also referred to as "on-press development step").

The lithographic method according to the present invention preferably comprises: a step of exposing the lithographic printing plate precursor according to the present invention to form an image (exposure step); a step (on-press development step) of supplying at least one selected from the group consisting of printing ink and fountain solution to remove the image-recording layer of the non-image portion on the printing press to produce a lithographic printing plate; and a step (printing step) of printing on the obtained lithographic printing plate.

Preferred embodiments of the method for producing a lithographic printing plate according to the present invention and the steps of the lithographic printing method according to the present invention will be described below in order. The lithographic printing plate precursor according to the present invention can also be developed with a developer.

Hereinafter, an exposure step and an on-press development step in the method for manufacturing a lithographic printing plate will be described, the exposure step in the method for manufacturing a lithographic printing plate according to the present invention is the same as the exposure step in the lithographic printing method according to the present invention, and the on-press development step in the method for manufacturing a lithographic printing plate according to the present invention is the same as the on-press development step in the lithographic printing method according to the present invention.

< Exposure Process >

The method for producing a lithographic printing plate according to the present invention preferably includes an exposure step of exposing the lithographic printing plate precursor according to the present invention in an image form to form exposed portions and unexposed portions. The lithographic printing plate precursor according to the present invention is preferably exposed to laser light through a transparent original having a line image, a halftone image, or the like, or is preferably exposed to light in an image form through laser scanning or the like based on digital data.

A light source having a wavelength of 750nm to 1,400nm can be preferably used. The light source of 750nm to 1,400nm is preferably a solid laser or a semiconductor laser that emits infrared rays. Regarding the infrared laser, the output is preferably 100mW or more, the exposure time per 1 pixel is preferably within 20 microseconds, and the irradiation energy is preferably 10mJ/cm ² ～300mJ/cm ² . In order to shorten the exposure time, a multi-beam laser apparatus is preferably used. The exposure mechanism may be any of an inner drum system, an outer drum system, a flat plate system, and the like.

As for the image exposure, a plate setter or the like can be used and performed by a conventional method. In the case of on-press development, the lithographic printing plate precursor may be mounted on a printing press and then subjected to image exposure on the printing press.

< on-machine development Process >

The method for producing a lithographic printing plate according to the present invention preferably includes an on-press development step of supplying at least one selected from the group consisting of printing ink and fountain solution on a printing press to remove an image recording layer of a non-image portion.

Hereinafter, an on-machine development method will be described.

[ on-machine development method ]

In the on-press development method, the image-exposed lithographic printing plate precursor is preferably supplied with an oil-based ink and an aqueous component on a printing press to remove the image-recording layer of the non-image portion to produce a lithographic printing plate.

That is, when the lithographic printing plate precursor is directly mounted on a printing press without any development treatment after image exposure, or after the lithographic printing plate precursor is mounted on the printing press, image exposure is performed on the printing press, and then the oil-based ink and the aqueous component are supplied and printing is performed, in an initial stage in the middle of printing, the image recording layer which is uncured by either or both of the supplied oil-based ink and the aqueous component is dissolved or dispersed and removed in a non-image portion, and a hydrophilic surface is exposed in this portion. On the other hand, the image recording layer cured by exposure in the exposure section forms an oil-based ink-receiving section having an oleophilic surface. The ink to be supplied to the plate surface may be an oil-based ink or an aqueous component, but the oil-based ink is preferably supplied at first from the viewpoint of preventing the contamination of the image recording layer from which the aqueous component has been removed. In this way, the lithographic printing plate precursor is subjected to on-press development on a printing press and is directly used for multi-sheet printing. As the oil-based ink and the aqueous component, a general printing ink for offset printing and a fountain solution are preferably used.

As the laser light for image-wise exposing the lithographic printing plate precursor according to the present invention, a laser light having a light source wavelength of 300nm to 450nm or 750nm to 1,400nm is preferably used. In the case of a light source of 300nm to 450nm, a lithographic printing plate precursor containing a sensitizing dye having an absorption maximum in the wavelength region in the image recording layer is preferably used, and a light source of 750nm to 1,400nm is preferably used. The light source of 300nm to 450nm is preferably a semiconductor laser.

< developing step with developer solution >

The method for producing a lithographic printing plate according to the present invention may include: a step of exposing the lithographic printing plate precursor of the present invention to an image; and a step of removing the image recording layer of the non-image portion with a developer to produce a lithographic printing plate (also referred to as a "developer development step").

The lithography method according to the present invention may include: a step of exposing the lithographic printing plate precursor of the present invention to an image; a step of removing the image recording layer of the non-image portion with a developing solution to produce a lithographic printing plate; and a step of printing by the obtained lithographic printing plate.

As the developer, a known developer can be used.

The pH of the developer is not particularly limited, and may be a strongly alkaline developer, but a developer having a pH of 2 to 11 is preferable. The developer having a pH of 2 to 11 is preferably a developer containing at least one of a surfactant and a water-soluble polymer compound.

In the developing treatment using the strongly alkaline developing solution, the following methods may be mentioned: the protective layer is removed by a pre-washing step, alkali development is performed, the alkali is removed by a post-washing step, a glue solution treatment is performed, and drying is performed by a drying step.

In the case of using the above-mentioned developer containing a surfactant or a water-soluble polymer compound, the developing-gum solution treatment can be performed simultaneously. Therefore, it is possible to perform the drying step after the development and the treatment with the gum solution with one liquid without particularly performing the post-washing step. Further, since the removal of the protective layer can be performed simultaneously with the development and the treatment with the gum solution, the pre-washing step is not particularly required. After the development treatment, it is preferable to remove the remaining developer using a squeegee roller or the like and then dry it.

< printing Process >

The lithographic printing method according to the present invention includes a printing step of supplying printing ink to a lithographic printing plate and printing a recording medium.

The printing ink is not particularly limited, and various known inks can be used as needed. Further, as the printing ink, oil-based ink or ultraviolet-curable ink (UV ink) can be preferably used.

In the printing step, a fountain solution may be supplied as needed.

The printing step may be performed without stopping the printing press, following the on-press development step or the developer development step.

The recording medium is not particularly limited, and a known recording medium can be used as needed.

In the method for producing a lithographic printing plate from a lithographic printing plate precursor according to the present invention and the lithographic printing method according to the present invention, the entire surface of the lithographic printing plate precursor may be heated before exposure, during exposure, or during exposure to development, as necessary. Such heating promotes an image forming reaction in the image forming layer, thereby providing advantages such as improved sensitivity or UV resistance and stabilized sensitivity. The heating before development is preferably performed under mild conditions of 150 ℃ or lower. In this way, problems such as curing of the non-image portion can be prevented. For the heating after the development, it is preferable to use very strong conditions, preferably in the range of 100 ℃ to 500 ℃. Within the above range, a sufficient image-strengthening effect can be obtained, and problems such as deterioration of the support body and thermal decomposition of the image portion can be suppressed.

Examples

The present invention will be described in detail below with reference to examples, but the present invention is not limited thereto. In the present example, "%" and "part" represent "% by mass" and "part by mass", respectively, unless otherwise specified. In addition, in the polymer compound, the molecular weight is a weight average molecular weight (Mw) and the ratio of the structural repeating units is a mole percentage unless otherwise specified. The weight average molecular weight (Mw) is a value measured as a polystyrene equivalent value by a Gel Permeation Chromatography (GPC) method.

(example 1-1 to example 1-18, example 2-1 to example 2-18, example 3-1 to example 3-3, and comparative example 1 to comparative example 3)

< production of support >

In order to remove the rolling oil on the surface of an aluminum plate (material JIS A1050) having a thickness of 0.3mm, after degreasing treatment at 50 ℃ for 30 seconds using a10 mass% sodium aluminate aqueous solution, 3 pieces of binding nylon Long Maoshua having a bundle diameter of 0.3mm and an pumice-water suspension (specific gravity 1.1 g/cm) having a median particle diameter of 25 μm were used ³ ) The aluminum plate surface was granulated and thoroughly washed with water. The aluminum plate was immersed in a 25 mass% aqueous solution of sodium hydroxide at 45 ℃ for 9 seconds to be etched and washed with water, and then immersed in a 20 mass% aqueous solution of nitric acid at 60 ℃ for 20 seconds to be washed with water. The etching amount of the grained surface was about 3g/m ² 。

Next, electrochemical surface roughening treatment was continuously performed using an alternating current voltage of 60 Hz. The electrolyte was a1 mass% aqueous solution of nitric acid (containing 0.5 mass% of aluminum ions), and the liquid temperature was 50 ℃. The ac power waveform was subjected to electrochemical surface roughening treatment using a carbon electrode as a counter electrode, using a trapezoidal rectangular wave ac with a time TP from zero to the peak of the current value of 0.8ms and a duty ratio of 1:1. Ferrite is used as the auxiliary anode. The current density is 30A/dm in terms of the peak value of the current ² And 5% of the current from the power supply is shunted to the auxiliary anode. The electric quantity in nitric acid electrolysis is 175C/dm when the aluminum plate is taken as the anode ² . Then, water washing was performed using a nebulizer.

Then, using an aqueous solution (containing 0.5 mass% of aluminum ions) of 0.5 mass% hydrochloric acid and an electrolyte solution having a liquid temperature of 50 ℃ and an electric quantity of 50℃/dm measured with an aluminum plate as an anode ² After the electrochemical surface roughening treatment by the same method as in nitric acid electrolysis, water washing was performed by a sprayer.

Then, on an aluminum plate, 15 mass% sulfuric acid water was addedSolution (containing 0.5 mass% of aluminum ions) as an electrolyte at a current density of 15A/dm ² Form 2.5g/m ² The dc anodized film of (1) was then washed with water and dried to prepare a support. The average pore diameter (surface average pore diameter) in the surface layer of the anodic oxide film was 10nm.

The pore diameter in the surface layer of the anodized film was measured by randomly extracting 50 pores and averaging the extracted pores by observing the surface at a magnification of 15 ten thousand times at a relatively low acceleration voltage of 12V using an ultra-high resolution SEM (scanning electron microscope, hitachi, ltd., product S-900) without conducting a deposition treatment for imparting conductivity. The standard deviation is ± 10% or less of the mean.

The obtained support was used as the support of example 1-1 to example 1-18, example 2-1 to example 2-18, and comparative example 1 to comparative example 3.

< production of supports S1 to S3 >

Surface treatment A

[ support body having large-diameter hole and small-diameter hole ]

(A-a) alkaline etching treatment

An etching treatment was performed by spraying an aqueous caustic soda solution having a caustic soda (sodium hydroxide) concentration of 26 mass% and an aluminum ion concentration of 6.5 mass% through a nozzle onto an aluminum plate at a temperature of 70 ℃. Then, water washing was performed using a nebulizer. Thereafter, the amount of aluminum dissolved in the surface subjected to the electrochemical surface roughening treatment was 1.0g/m ² 。

(A-b) desmutting treatment in acidic aqueous solution (1 st desmutting treatment)

Subsequently, a desmutting treatment was performed in an acidic aqueous solution. As the acidic aqueous solution used for the desmutting treatment, an aqueous solution of sulfuric acid of 150g/L was used. The liquid temperature was 30 ℃. The desmutting liquid was sprayed by a sprayer and desmutting treatment was performed for 3 seconds. After that, water washing treatment was performed.

(A-c) electrochemical surface roughening treatment in hydrochloric acid aqueous solution

Then, hydrochloric acid of 14g/L concentration and aluminum ions were usedElectrolytic surface roughening treatment was performed using an alternating current in an electrolytic solution having a concentration of 13g/L and a sulfuric acid concentration of 3 g/L. The liquid temperature of the electrolyte was 30 ℃. The aluminum ion concentration was adjusted by adding salted aluminum. The AC current has a waveform of sine wave with symmetrical positive and negative waveforms, a frequency of 50Hz, an anode reaction time and a cathode reaction time of 1:1 in 1 cycle of the AC current, and a current density of 75A/dm (peak current value) of the AC current waveform ² . The amount of electricity was 450C/dm, based on the total amount of electricity accumulated in the aluminum plate during the anode reaction ² The electrolytic treatment is carried out at every 125C/dm ² The energization was performed in four times with an interval of 4 seconds. The carbon electrode was used as a counter electrode for the aluminum plate. Thereafter, water washing treatment was performed.

(A-d) alkali etching treatment

An etching treatment was performed by spraying an aqueous caustic soda solution having a caustic soda concentration of 5 mass% and an aluminum ion concentration of 0.5 mass% through a nozzle onto the aluminum plate having undergone the electrochemical surface roughening treatment at a temperature of 45 ℃. The amount of aluminum dissolved in the surface subjected to the electrochemical surface roughening treatment was 0.2g/m ² . Thereafter, water washing treatment was performed.

(A-e) decontamination treatment in acidic aqueous solution

Subsequently, a desmutting treatment was performed in an acidic aqueous solution. As the acidic aqueous solution used for the desmear treatment, a waste liquid (aluminum ions 5.0g/L dissolved in an aqueous solution of sulfuric acid 170 g/L) generated in the anodizing treatment step was used. The liquid temperature was 30 ℃. The desmutting liquid was sprayed by a sprayer and desmutting treatment was performed for 3 seconds.

(A-f) anodic Oxidation treatment at stage 1

The anodic oxidation treatment of stage 1 was performed using an anodic oxidation apparatus based on direct current electrolysis having the structure shown in fig. 3. An anodic oxide film having a predetermined film thickness was formed by performing the anodic oxidation treatment under the conditions shown in table 1.

In the anodizing apparatus 610, the aluminum plate 616 is conveyed as indicated by an arrow in fig. 3. The aluminum plate 616 is charged to (+) in a power feeding tank 612 in which an electrolyte 618 is stored through a power feeding electrode 620. Aluminum plate 616 is transferred upward by rollers 622 in power supply tank 612, is changed in direction downward by nip rollers 624, is transferred to electrolytic treatment tank 614 in which electrolytic solution 626 is stored, and is changed in direction horizontally by rollers 628. Then, the aluminum plate 616 is charged (-) by the electrolytic electrode 630 to form an anodic oxide film on the surface thereof, and the aluminum plate 616 which has left the electrolytic processing bath 614 is conveyed to a post-process. In the anodizing apparatus 610, a direction changing mechanism is constituted by the roller 622, the grip roller 624, and the roller 628, and the aluminum sheet 616 is conveyed in a mountain shape and an inverted U shape by the roller 622, the grip roller 624, and the roller 628 in the gap portion between the power feeding bath 612 and the electrolytic treatment bath 614. The feeding electrode 620 and the electrolysis electrode 630 are connected to a dc power supply 634.

(A-g) Kong Anjiao treatment

The anodized aluminum plate was immersed in a caustic soda aqueous solution having a caustic soda concentration of 5 mass% and an aluminum ion concentration of 0.5 mass% at a temperature of 35 ℃ under the conditions shown in table 1, to thereby carry out the treatment Kong Anjiao. Then, water washing was performed using a nebulizer.

(A-h) anodic Oxidation treatment at stage 2

The anodic oxidation treatment of the 2 nd stage was performed using the anodic oxidation apparatus of direct current electrolysis based on the configuration shown in fig. 3. An anodic oxide film having a predetermined film thickness was formed by performing the anodic oxidation treatment under the conditions shown in table 1.

The support S1 of the example was obtained from the above surface treatment a.

The anodic oxide film having micropores after the 2 nd anodic oxidation treatment step obtained above was subjected to the average diameter (nm) on the surface of the anodic oxide film of the large-diameter pores, the average diameter (nm) at the positions where the small-diameter pores communicate with each other, the depths (nm) of the large-diameter pores and the small-diameter pores, and the pit density (density and unit of micropores; unit/μm/pore) ² ) And the thickness (nm) of the anodic oxide coating from the bottom of the small-diameter hole to the surface of the aluminum plate are summarized in table 2.

The average diameter of the micropores (average diameter of the large-diameter pores and the small-diameter pores) was a value obtained by observing N =4 large-diameter pore surfaces and small-diameter pore surfaces with an FE-SEM having a magnification of 15 ten thousand times, and measuring and averaging the diameters of micropores (large-diameter pores and small-diameter pores) existing in a range of 400nm × 600nm in the obtained 4 images. In the case where the large-diameter hole has a deep depth and it is difficult to measure the diameter of the small-diameter hole, and in the case where the large-diameter hole is measured, the upper portion of the anodized film is cut, and then various diameters are obtained.

The depth of each of the micropores (the depth of the large-diameter hole portion and the small-diameter hole portion) was a value obtained by observing the cross section of the support (anodic oxide film) by FE-SEM (observation of the depth of the large-diameter hole portion: 15 ten thousand times and observation of the depth of the small-diameter hole portion: 5 ten thousand times), and the depth of 25 arbitrary micropores was measured and averaged in the obtained image.

In table 1, the coating Amount (AD) in the column 1 of the anodic oxidation treatment and the coating Amount (AD) in the column 2 of the anodic oxidation treatment indicate the coating amounts obtained in the respective treatments. The electrolyte used was an aqueous solution containing the components shown in table 1.

Surface treatment B

[ support body having large-diameter hole portion ]

(B-a) alkali etching treatment

An etching treatment was performed by spraying an aqueous caustic soda solution having a caustic soda concentration of 26 mass% and an aluminum ion concentration of 6.5 mass% through a nozzle onto an aluminum plate at a temperature of 70 ℃. Then, water washing was performed using a nebulizer. Thereafter, the amount of aluminum dissolved in the surface subjected to the electrochemical surface roughening treatment was 1.0g/m ² 。

(B-B) desmutting treatment in acidic aqueous solution (1 st desmutting treatment)

Subsequently, a desmutting treatment was performed in an acidic aqueous solution. As the acidic aqueous solution used for the desmutting treatment, an aqueous solution of sulfuric acid of 150g/L was used. The liquid temperature was 30 ℃. The decontamination solution was sprayed by a sprayer and decontamination treatment was performed for 3 seconds. After that, water washing treatment was performed.

(B-c) electrochemical surface roughening treatment in hydrochloric acid aqueous solution

Next, electrolytic surface roughening treatment was performed by using an alternating current with an electrolytic solution having a hydrochloric acid concentration of 14g/L, an aluminum ion concentration of 13g/L, and a sulfuric acid concentration of 3 g/L. The liquid temperature of the electrolyte was 30 ℃. The aluminum ion concentration was adjusted by adding aluminum salt.

The waveform of the alternating current is sine wave with symmetrical positive and negative waveforms, the frequency is 50Hz, the anode reaction time and the cathode reaction time in 1 period of the alternating current are 1:1, and the current density is 75A/dm of the peak current value of the waveform of the alternating current ² . The amount of electricity was 450C/dm, based on the total amount of electricity accumulated in the aluminum plate during the anode reaction ² The electrolytic treatment is carried out at every 125C/dm ² The energization was performed in four times with an interval of 4 seconds. The carbon electrode was used as a counter electrode for the aluminum plate. Thereafter, water washing treatment was performed.

(B-d) alkali etching treatment

An etching treatment was performed by spraying an aqueous caustic soda solution having a caustic soda concentration of 5 mass% and an aluminum ion concentration of 0.5 mass% through a nozzle onto the aluminum plate having undergone the electrochemical surface roughening treatment at a temperature of 45 ℃. The amount of aluminum dissolved in the surface subjected to the electrochemical surface roughening treatment was 0.2g/m ² . After that, water washing treatment was performed.

(B-e) decontamination treatment in acidic aqueous solution

Subsequently, a desmutting treatment was performed in an acidic aqueous solution. As the acidic aqueous solution used for the desmear treatment, a waste liquid (aluminum ions 5.0g/L dissolved in an aqueous solution of sulfuric acid 170 g/L) generated in the anodizing treatment step was used. The liquid temperature was 30 ℃. The decontamination solution was sprayed by a sprayer and decontamination treatment was performed for 3 seconds.

(B-f) anodic Oxidation treatment of No. 1

(B-g) Kong Anjiao treatment

The support S2 of the example was obtained from the above surface treatment B. The details of the support body S2 obtained are shown in table 2.

Surface treatment C

[ support body having large-diameter hole portion ]

(C-a) alkali etching treatment

(C-b) desmutting treatment in acidic aqueous solution (1 st desmutting treatment)

Subsequently, a desmutting treatment was performed in an acidic aqueous solution. As the acidic aqueous solution used for the desmutting treatment, an aqueous solution of sulfuric acid of 150g/L was used. The liquid temperature was 30 ℃. The decontamination solution was sprayed by a sprayer and decontamination treatment was performed for 3 seconds. Thereafter, water washing treatment was performed.

(C-C) electrochemical surface roughening treatment in hydrochloric acid aqueous solution

Next, electrolytic surface roughening treatment was performed by using an alternating current with an electrolyte solution having a hydrochloric acid concentration of 14g/L, an aluminum ion concentration of 13g/L, and a sulfuric acid concentration of 3 g/L. The liquid temperature of the electrolyte was 30 ℃. The aluminum ion concentration was adjusted by adding aluminum salt.

The waveform of the alternating current is sine wave with symmetrical positive and negative waveforms, the frequency is 50Hz, the anode reaction time and the cathode reaction time in 1 period of the alternating current are 1:1, and the current density is 75A/dm of the peak current value of the waveform of the alternating current ² . And, the electric quantity toThe sum of the electric quantities accumulated when the aluminum plate was subjected to the anode reaction was 450C/dm ² The electrolytic treatment is carried out at every 125C/dm ² Four times with a4 second conduction interval. The carbon electrode was used as a counter electrode for the aluminum plate. After that, water washing treatment was performed.

(C-d) decontamination treatment in acidic aqueous solution

Next, the desmear treatment was performed in an acidic aqueous solution without performing the alkali etching treatment. As the acidic aqueous solution used for the desmear treatment, a waste liquid (aluminum ions 5.0g/L dissolved in an aqueous solution of sulfuric acid 170 g/L) generated in the anodizing treatment step was used. The liquid temperature was 30 ℃. The desmutting liquid was sprayed by a sprayer and desmutting treatment was performed for 3 seconds.

(C-e) anodic Oxidation treatment of No. 1

The anodic oxidation treatment at stage 1 was performed using an anodic oxidation apparatus based on direct current electrolysis having the structure shown in fig. 3. An anodic oxide film having a predetermined film thickness was formed by performing the anodic oxidation treatment under the conditions shown in table 1.

(C-f) Kong Anjiao treatment

The anodized aluminum plate was immersed in a caustic soda aqueous solution having a caustic soda concentration of 5 mass% and an aluminum ion concentration of 0.5 mass% at a temperature of 30 ℃ under the conditions shown in table 1, to thereby carry out the treatment Kong Anjiao. Then, water washing was performed using a nebulizer.

The supports S-1 to S-3 of the examples were obtained from the surface treatment C described above. The details of the obtained supports S-1 to S-3 are shown in Table 1.

(C-g) anodic Oxidation treatment of No. 1

The anodic oxidation treatment at the 2 nd stage was performed using an anodic oxidation apparatus based on direct current electrolysis having the structure shown in fig. 3. An anodic oxide film having a predetermined film thickness was formed by performing an anodic oxidation treatment under the conditions shown in table 1.

[ Table 1]

< formation of lithographic printing plate precursor >

An undercoat liquid (1) having the following composition was applied to the support so that the amount of the applied liquid was 20mg/m in dry condition ² And dried at 100 ℃ for 30 seconds by an oven, thereby producing a support having an undercoat layer.

The following image recording layer coating liquid (1) was bar-coated on the undercoat layer, and dried at 100 ℃ for 60 seconds to form a dry coating weight of 0.60g/m ² (film thickness = about 0.60 μm), thereby obtaining a lithographic printing plate precursor.

Thereafter, an overcoat coating liquid (1) having the following composition was applied on the image recording layer and dried at 100 ℃ for 60 seconds to give a dry coating amount of 1.0g/m ² An overcoat layer (containing a hydrophobic portion) (film thickness = about 1.0 μm), thereby obtaining a lithographic printing plate precursor.

[ base coating liquid (1) ]

The following undercoating compound 1:0.18 part

Methanol: 55.24 parts

Distilled water: 6.15 parts

Synthesis of priming Compound 1

< purification of monomer M-1 >)

LIGHT ESTER P-1M (2-methacryloyloxyethyl acid phosphate, KYOEISHA CHEMICAL CO., LTD. Manufactured) 420 parts, diethylene glycol dibutyl ether 1,050 parts and distilled water 1,050 parts were added to a separatory funnel, vigorously stirred and then allowed to stand. After discarding the upper layer, 1,050 parts of diethylene glycol dibutyl ether was added, vigorously stirred, and then allowed to stand. The upper layer was discarded to obtain 1,300 parts of an aqueous solution of the monomer M-1 (10.5 mass% in terms of solid content).

< Synthesis of undercoating Compound 1 >

53.73 parts of distilled water and 3.66 parts of the monomer m-2 shown below were charged into a three-necked flask, and the temperature was raised to 55 ℃ under a nitrogen atmosphere. Subsequently, the dropwise addition solution 1 shown below was added dropwise over 2 hours and stirred for 30 minutes, followed by addition of 0.386 part of VA-046B (manufactured by FUJIFILM Wako Pure Chemical Corporation), warming to 80 ℃ and stirring for 1.5 hours. After the reaction mixture was returned to room temperature (25 ℃), a 30 mass% aqueous solution of sodium hydroxide was added to adjust the pH to 8.0, and then 0.005 part of 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl (4-OH-TEMPO) was added. Through the above operations, 180 parts of an aqueous solution of the undercoating compound 1 was obtained. The weight average molecular weight (Mw) as a polyethylene glycol converted value by a Gel Permeation Chromatography (GPC) method was 17 ten thousand.

[ chemical formula 55]

Dripping solution 1

Aqueous solution of the above monomer M-1: 87.59 parts

The above monomer m-2:14.63 parts

VA-046B (2,2' -azobis [2- (2-imidazolin-2-yl) propane ] disulfate dihydrate, manufactured by FUJIFILM Wako Pure Chemical Corporation): 0.386 part

Distilled water: 20.95 parts

< coating liquid (1) for image recording layer >

Infrared absorbers described in tables 2 to 4: the amounts shown in tables 2 to 4

Polymerizable compounds described in tables 2 to 4: the amounts shown in tables 2 to 4

Binder polymers described in tables 2 to 4: the amounts shown in tables 2 to 4

Electron-donating polymerization initiators shown in tables 2 to 4: the amounts shown in tables 2 to 4

Electron acceptors described in tables 2 to 4 as polymerization initiators: the amounts shown in tables 2 to 4

Acid developers described in tables 2 to 4: the amounts shown in tables 2 to 4

NK ester A-9300 (Shin-Nakamura Chemical Co., ltd.): 0.100 part

A-DPH (Shin-Nakamura Chemical Co., ltd.): 0.100 part

BYK306 (Byk Chemie Co.): 0.008 portion

1-methoxy-2-propanol: 8.609 parts

Methyl ethyl ketone: 1.091 parts

< overcoat coating liquid >

POVAL PVA105 (KURARAY co., ltd. System, saponification degree 80% or more): 0.6 part by mass

PEG4000 (Tokyo Chemical Industry co., ltd.): 0.39 parts by mass

Surfactant (RAPISOLA-80, manufactured by NOF CORPORATION): 0.01 part by mass

Water: the whole amount is 10 parts by mass

< evaluation >

[ color rendering (Δ L) ]

The lithographic printing plate precursor obtained was exposed to light with an output of 11.7W, an outer drum rotation speed of 250rpm, and a resolution of 2,400dpi (point per inch, 1 inch =25.4 mm) by Trendsetter3244VX, manufactured by Creo corporation, which was a water-cooled 40W infrared semiconductor laser. Exposure was carried out in an environment of 25 ℃ and 50% RH.

The color development of the lithographic printing plate precursor was measured immediately after exposure and after storage in the dark (25 ℃ C.) for 2 hours after exposure. The measurement was carried out by SCE (specular reflectance removal) using a spectrocolorimeter CM2600d manufactured by Konica minolta inc., and operating software CM-S100W.

Regarding color rendering properties, L is used ^* a ^* b ^* L of the color system ^* Value (lightness) according to L of the exposed part ^* Value and L of unexposed portion ^* The difference Δ L between the values was evaluated. The values of Δ L are shown in table 1. The larger the value of Δ L, the more excellent the color rendering property. The larger the value of Δ L after 2 hours of exposure (numerical value in the column of "color developability (after 2 hours)" in the table), the more excellent the color developability during exposure. Further, it can be said that the larger the value of Δ L, the more excellent the plate detection property.

[ UV resistance to brushing ]

The lithographic printing plate precursor obtained was exposed to light at an outer drum rotation speed of 1,000rpm and a laser output of 70% with a resolution of 2,400dpi by Luxel PLATESETTER T-6000III manufactured by Fujifilm Corporation carrying an infrared semiconductor laser. The exposure image was set to include a solid image, a 50% halftone dot pattern of 20 μm-dot FM screening, and a non-image portion.

The obtained exposed lithographic printing original plate was mounted on a plate cylinder of a printer LITHONE 26 made by KOMORI Corporation without being subjected to a development process. After on-line development by supplying fountain solution and ink by the standard automatic printing start method of LITHRONE26 using eco-2 (manufactured by Fujifilm Corporation)/tap water =2/98 (capacity ratio) fountain solution and UV ink (T & K UV OFS K-HS ink GE-M (T & K TOKA co., ltd. Manufactured)) on the basis of decelerating the water supply roller by 5% with respect to the plate cylinder, 50,000 sheets were printed on Tokubishi Art (Mitsubishi Oji Paper co., ltd. Manufactured, continuous amount: 76.5 kg) Paper at a printing speed of 10,000 sheets per hour.

As the number of printed sheets increases, the image recording layer gradually wears and the ink receptivity decreases, so the ink concentration on the printing paper decreases. The number of printed copies was determined to be 5% lower than the measured value of the 100 th printed sheet by measuring the dot area ratio of 3% frequency-modulated halftone dots in the printed matter by x-Rite (x-Rite), and UV brushing resistance was evaluated.

[ on-machine developability ]

The lithographic printing plate precursor obtained was exposed to light at an outer drum rotation speed of 1,000rpm and a laser output of 70% with a resolution of 2,400dpi by Luxel PLATESETTER T-6000III manufactured by Fujifilm Corporation carrying an infrared semiconductor laser. The exposure image was set to include a solid image, a 50% halftone image of 20 μm dot FM screen, and a non-image portion.

The obtained exposed master was mounted on a plate cylinder of a printer LITHONE 26 made by KOMORI Corporation without being subjected to a development process. After on-machine development was performed by supplying fountain solution and ink by the standard automatic print start method of printer LITHRONE26 manufactured by KOMORI Corporation using Ecol ity-2 (manufactured by Fuj ifi lm Corporation)/tap water =2/98 (volume ratio) fountain solution and Space Color Fusion G yellow ink (manufactured by DIC Graphics Corporation), 500 sheets were printed on Tokubishi Art (Mitsubishi Oji Paper salts Co., ltd., continuous amount: 76.5 kg) Paper at a print speed of 10,000 sheets per hour.

The number of sheets of printing paper required until the unexposed portion of the image recording layer was developed on the printing press on the machine, and the ink was not transferred to the non-image portion was measured as on-machine developability. It can be said that the smaller the number of sheets, the more excellent the on-press developability.

The unit of the addition amount of each component in tables 2 to 4 is part by mass. In tables 2 to 4, "-" indicates that no corresponding component is included.

The details of the compounds shown in tables 2 to 4 are as follows.

< Infrared absorber >

IR-1 to IR-9: the infrared ray absorber (specific infrared ray absorber) represented by the above formula 1-1

IR-11: the following infrared absorbers are those which are not decomposed by heat or infrared exposure.

Further, tsO in the following compounds ^- Represents a p-toluenesulfonate anion, and Ph represents a phenyl group.

[ chemical formula 56]

[ chemical formula 57]

[ chemical formula 58]

[ chemical formula 59]

< polymerizable Compound >

M-1: the following compounds, molecular weight 423.58, ethylenically unsaturated bond equivalent 141.13, clogP 2.59

M-2: the following compounds, molecular weight 1,217.23, ethylenically unsaturated equivalent 121.72, clogP 5.92

M-3: the following compounds, molecular weight 578.57, equivalent of ethylenic unsaturation 96.43, clogP 5.08

[ chemical formula 60]

[ chemical formula 61]

< adhesive Polymer >

P-1 to P-10: specific binder polymers shown below. In the following structural units, the subscripts a to d in parentheses represent the content (mass ratio) of each structural unit.

Acrylic resin: polymethyl methacrylate (PMMA), manufactured by Aldrich, mw: about 120,000

The weight average molecular weights (Mw) of P-1 to P-10 are all 3,000 to 300,000.

[ chemical formula 62]

[ chemical formula 63]

[ chemical formula 64]

[ Synthesis of adhesive Polymer ]

Synthesis of-P-1

300 parts of methyl ethyl ketone was added to a three-necked flask, and the mixture was heated to 80 ℃ under a nitrogen stream. To the reaction vessel, a mixed solution containing 83.3 parts of styrene, 16.7 parts of acrylonitrile, 0.7 part of AIBN (azobisisobutyronitrile), and 100 parts of methyl ethyl ketone was added dropwise over 30 minutes. After the completion of the dropwise addition, the reaction was continued for 7.5 hours. Then, 0.3 part of AIBN was added and the reaction was continued for 12 hours. After the reaction was completed, the reaction solution was cooled to room temperature. The composition ratio of structural units derived from styrene to structural units derived from acrylonitrile in P-1 obtained was 5:1 (mass ratio).

Synthesis of-P-2-P-10

P-2 to P-10 were prepared in the same manner as for the synthesis of P-1, except that the kind and amount of the monomer used were changed.

Synthesis of Polymer particles 1

A solution of 20 parts of methyl polyethylene glycol methyl ether acrylate (PEGMA) dissolved in a mixture of 50.5 parts of deionized water and 242.2 parts of N-propanol was charged into a four-necked flask and placed in a nitrogen atmosphere ₂ Heat slowly under atmosphere until slightly refluxed (-73 ℃). A premix of styrene (9 parts), acrylonitrile (81 parts), and VAZO-64 (2,2' -azobis (isobutyronitrile), 0.7 parts) was added over 2 hours. After 6 hours, further 0.5 part of VAZO-64 was added. Increase the temperatureTo 80 ℃. Then, 0.7 part of VAZO-64 was added thereto over 12 hours. After a total reaction time of 20 hours, the conversion to graft copolymer, determined as a percentage of nonvolatile content, was > 98%. The mass ratio PEGMA/styrene/acrylonitrile is 10. The number average particle diameter of the polymer particles was 200nm.

The number average particle diameter is a value obtained by taking an electron micrograph of polymer particles, measuring the equivalent circle diameter of 5,000 particles in total on the micrograph, and averaging. The circle-equivalent diameter represents the diameter of a circle of the same area as the projected area on the photograph of the particle.

[ Electron donating polymerization initiators ]

D-1 to D-6: the following compounds

In addition, bu in the following compounds represents n-butyl.

Also, the HOMO of D-6 was-5.905 eV and the LUMO was-3.250 eV.

[ chemical formula 65]

[ chemical formula 66]

< Electron accepting type polymerization initiator >

IA-1: the following compounds

[ chemical formula 67]

IS-1 to IS-6: the following compounds

[ chemical formula 68]

Acid developer

CA-1: the following compounds

[ chemical formula 69]

It is found that the lithographic printing plates of examples 1-1 to 1-18 and examples 2-1 to 2-18, which are the lithographic printing plate precursors according to the present invention, have excellent printing durability even when UV ink is used, as compared with the lithographic printing plate precursors of comparative examples 1 to 3.

It is also found that the lithographic printing plate precursors of examples 2-1 to 2-18, which are lithographic printing plate precursors according to the present invention, are excellent in color developability, color developability with time after exposure, and on-press developability.

The disclosures of Japanese patent application No. 2018-205752, filed on 31/10/2018, and Japanese patent application No. 2019-122487, filed on 28/6/2019, are incorporated herein by reference in their entirety.

All documents, japanese patent applications, and technical standards described in the present specification are incorporated by reference in the present specification in the same manner as in the case where each of the documents, japanese patent applications, and technical standards incorporated by reference is specifically and individually described.

Description of the symbols

12a, 12b-aluminum support, 14-undercoat layer, 16-image recording layer, 20a, 20b-anodic oxidation coating, 22a, 22b-micropores, 24-large-diameter hole portions, 26-small-diameter hole portions, and D-depth of large-diameter hole portions, 610-anodic oxidation treatment device, 612-power supply tank, 614-electrolytic treatment tank, 616-aluminum plate, 618,626-electrolyte solution, 620-power supply electrode, 622,628-roller, 624-clamping roller, 630-electrolytic electrode, 632-groove wall, and 634-direct current power supply.

Claims

1. A lithographic printing plate precursor having an image-recording layer on a support,

the image recording layer comprises an infrared absorbing agent represented by the following formula 1-1, a polymerization initiator, a polymerizable compound, and a binder polymer having a structural unit formed from an aromatic vinyl compound and a structural unit formed from an acrylonitrile compound,

in the formula 1-1, R ¹ Represents a group represented by the following formula 2, R ₁₁ ～R ₁₈ Each independently represents a hydrogen atom, a halogen atom, -R ^a 、-OR ^b 、-SR ^c or-NR ^d R ^e ，R ^a ～R ^e Each independently represents a hydrocarbon group, A ₁ 、A ₂ And a plurality of R ₁₁ ～R ₁₈ Optionally linked to form a monocyclic or polycyclic ring, A ₁ And A ₂ Each independently represents an oxygen atom, a sulfur atom or a nitrogen atom, n ₁₁ And n ₁₂ Each independently represents an integer of 0 to 5, wherein n ₁₁ And n ₁₂ Is 2 or more, n ₁₃ And n ₁₄ Each independently represents 0 or 1,L represents an oxygen atom, a sulfur atom or-NR ¹⁰ -，R ¹⁰ Represents a hydrogen atom, an alkyl group or an aryl group, za represents a counter ion for neutralizing a charge,

in formula 2, R ^Z Represents an alkyl group, a wavy line represents a bonding site to a group represented by L in the formula 1-1,

the polymerization initiator includes at least one polymerization initiator selected from the group consisting of electron donating polymerization initiators and electron accepting polymerization initiators,

the polymerizable compound has a polymerizable group having 7 or more functions,

the content of the structural unit composed of the aromatic vinyl compound is 30 to 70 mass% with respect to the total mass of the binder polymer, and the content of the structural unit composed of the acrylonitrile compound is 8 to 70 mass% with respect to the total mass of the binder polymer.

2. The lithographic printing plate precursor according to claim 1,

the infrared absorber is a cyanine dye represented by the following formula 1-2,

in the formula 1-2, R ¹ Represents a group represented by the following formula 2, R ² And R ³ Each independently represents a hydrogen atom or an alkyl group, R ² And R ³ Optionally linked to each other to form a ring, ar ¹ And Ar ² Each independently represents a group forming a benzene ring or a naphthalene ring, Y ¹ And Y ² Each independently represents an oxygen atom, a sulfur atom, -NR ⁰ Or a dialkylmethylene group, R ⁰ Represents a hydrogen atom, an alkyl group or an aryl group, R ⁴ And R ⁵ Each independently represents an alkyl group, -CO ₂ M radical or-PO ₃ M ₂ M represents a hydrogen atom, a sodium atom, a potassium atom or an onium group, R ⁶ ～R ⁹ Each independently represents a hydrogen atom or an alkyl group, L represents an oxygen atom, a sulfur atom or-NR ¹⁰ -，R ¹⁰ Represents a hydrogen atom, an alkyl group or an aryl group, za represents a counter ion for neutralizing a charge,

in formula 2, R _Z Represents an alkyl group, and the wavy line represents a bonding site to the group represented by L in the formula 1-2.

3. The lithographic printing plate precursor according to claim 1 or 2, wherein,

l in the formula 1-1 represents a sulfur atom or-NR ¹⁰ -, said R ¹⁰ Represents a hydrogen atom, an alkyl group or an aryl group.

4. The lithographic printing plate precursor according to claim 3,

r in the formula 1-2 ⁴ And R ⁵ Each independently represents-R ^w4 -SO ₃ M represents a hydrogen atom, a sodium atom, a potassium atom or an onium group, and R ^w4 Represents a single bond or an alkylene group having 1 to 12 carbon atoms.

5. The lithographic printing plate precursor according to claim 1 or 2,

l in the formula 1-1 is an oxygen atom.

6. The lithographic printing plate precursor according to claim 1 or 2,

the polymerizable compound has a polymerizable group having 10 or more functions.

7. The lithographic printing plate precursor according to claim 1 or 2,

the polymerizable compound has an equivalent weight of an ethylenically unsaturated bond of 200g/mol or less.

8. The lithographic printing plate precursor according to claim 1 or 2, wherein,

the polymerizable compound has a CLogP of 6 or less.

9. The lithographic printing plate precursor according to claim 1 or 2,

the polymerizable group of the polymerizable compound includes a vinyl group or a (meth) acryloyl group.

10. The lithographic printing plate precursor according to claim 1 or 2,

the image recording layer further comprises polymer particles.

11. The lithographic printing plate precursor according to claim 10,

the polymer particles comprise polymer particles having hydrophilic groups.

12. The lithographic printing plate precursor according to claim 11,

the polymer particles have a polyalkylene oxide structure as the hydrophilic group.

13. The lithographic printing plate precursor according to claim 1 or 2,

the electron-donating polymerization initiator is an onium salt compound.

14. The lithographic printing plate precursor according to claim 1 or 2, wherein,

the electron-donating polymerization initiator has a HOMO of-6.0 eV or more.

15. The lithographic printing plate precursor according to claim 1 or 2,

the electron accepting polymerization initiator has a LUMO of-3.0 eV or less.

16. The lithographic printing plate precursor according to claim 1 or 2,

the polymerization initiator is a compound that forms a counter salt from the electron-donating polymerization initiator and the electron-accepting polymerization initiator.

17. The lithographic printing plate precursor according to claim 1 or 2,

the image recording layer further comprises an acid developer.

18. The lithographic printing plate precursor according to claim 1 or 2,

an overcoat layer is also provided on the image recording layer.

19. The lithographic printing plate precursor according to claim 1 or 2, wherein,

the support body has an aluminum plate and an anodic oxide coating of aluminum disposed on the aluminum plate,

the anodic oxide coating is positioned on the image recording layer side of the aluminum plate,

the anodic oxide film has micropores extending in a depth direction from a surface on the image-recording layer side,

the average diameter of the micropores on the surface of the anodic oxide film is more than 10nm and 100nm or less.

20. The lithographic printing plate precursor according to claim 19,

the micropores are composed of large-diameter holes extending from the surface of the anodic oxidation coating to a position with a depth of 10nm to 1000nm and small-diameter holes communicating with the bottoms of the large-diameter holes and extending from the communicating position to a position with a depth of 20nm to 2000nm,

the average diameter of the large-diameter pores on the surface of the anodic oxide coating is 15 to 100nm,

an average diameter of the small-diameter hole portions at the communication positions is 13nm or less.

21. A method of making a lithographic printing plate, the method comprising:

a step of exposing the lithographic printing plate precursor according to any one of claims 1 to 20 to an image; and

22. A lithographic method, comprising:

a step of exposing the lithographic printing plate precursor according to any one of claims 1 to 20 to form an image;

a step of performing printing by the obtained lithographic printing plate.