JP2020122934A - Positive lithographic printing plate precursor, and method of making lithographic printing plate - Google Patents

Abstract

To provide a positive lithographic printing plate precursor capable of preventing ablation well, and a method of making a lithographic printing plate using the positive lithographic printing plate precursor.SOLUTION: A positive lithographic printing plate precursor has a support, and an image recording layer formed on the support. The image recording layer has a binder polymer having a constitutional unit with a base group, an acidic compound having two or more acid radicals and having a molecular weight of 10,000 or less, and an infrared absorber. There is also provided a method of making a lithographic printing plate using the positive lithographic printing plate precursor.SELECTED DRAWING: None

Description

The present disclosure relates to a positive lithographic printing plate precursor and a method for producing a lithographic printing plate.

In general, a lithographic printing plate comprises a lipophilic image area that receives ink during the printing process and a hydrophilic non-image area that receives fountain solution. In lithographic printing, the lipophilic image part of the lithographic printing plate is used as the ink receiving part and the hydrophilic non-image part is dampening water receiving part (ink non-receiving part) by utilizing the property that water and oil-based ink repel each other. As a method, the difference in ink adhesion is caused on the surface of the lithographic printing plate, the ink is applied only to the image portion, and then the ink is transferred to a printing medium such as paper to perform printing.
Such a lithographic printing plate is, for example, a support and an image recording layer formed on the support by a method such as applying a photosensitive resin composition containing a polymer compound and a solvent onto the support, and drying. It is manufactured by developing a lithographic printing plate precursor having

In Patent Document 1, a planographic printing plate precursor having an image recording layer containing a binder polymer on a support is cured by imagewise exposure to cure the image recording layer in the exposed area, and then the pH is adjusted to 2.0 to 8.0. The method for making a lithographic printing plate, wherein the development is carried out with the treatment liquid of (1), wherein the binder polymer has a structure having at least an amino group and/or an ammonium group, and the development treatment liquid is a surfactant containing a nitrogen atom. A plate-making method of a lithographic printing plate containing at least one of the above is disclosed.

JP, 2008-276210, A

In the positive type lithographic printing plate precursor, unlike the negative type lithographic printing plate precursor in which the exposed portion is cured, for example, ablation may occur during exposure during image formation.
Ablation is a phenomenon in which the image recording layer explosively expands due to heat generated during exposure and is volatilized or decomposed and removed. When the above-mentioned ablation occurs, problems such as contamination of the optical system used for exposure may occur due to scattered matter such as components of the image recording layer.
Therefore, in the positive type lithographic printing plate precursor, it is required to suppress ablation during exposure.
In the present disclosure, the property that such occurrence of ablation is easily suppressed is also referred to as excellent ablation suppression property.
The lithographic printing plate precursor described in Patent Document 1 is a negative lithographic printing plate precursor in which the image recording layer contains a polymerizable compound, a polymerization initiator, and a binder polymer having an amino group and/or an ammonium group. Ablation does not occur, and it does not require the ability to suppress ablation.

The problem to be solved by the embodiments of the present disclosure is to provide a positive lithographic printing plate precursor excellent in ablation suppression property, and a method for producing a lithographic printing plate using the positive lithographic printing plate precursor. ..

Means for solving the above problems include the following aspects.
<1> having a support and an image recording layer formed on the support,
The image recording layer is
A binder polymer having a structural unit having a basic group,
An acidic compound having two or more acid groups and having a molecular weight of 10,000 or less;
A positive planographic printing plate precursor containing an infrared absorber.

<2> The positive type as described in <1>, in which the binder polymer has a constitutional unit represented by the following formula (1), the following formula (2), or the following formula (3) as a constitutional unit having a basic group. Original planographic printing plate.

In formulas (1) to (3), R ¹ represents a hydrogen atom or a methyl group, X ¹ represents a single bond, an ester bond or an amide bond, and L ^{1 to} L ⁴ each independently represent a single bond or a divalent group. , Base ¹ and Base ² each independently represent a monovalent base group, Base ³ represents a divalent base group, and Y ^{1 to} Y ⁴ each independently represent -O- or -NR-. R represents a hydrogen atom or an alkyl group, and A ¹ represents a trivalent linking group. A ¹ or L ² and Base ² may combine to form a ring, or at least one of L ³ and L ⁴ and Base ³ may combine to form a ring, and L ³ and L ⁴ And may combine with each other to form a ring.

<3> The positive type lithographic printing plate precursor as described in <1> or <2>, wherein the basic group is a group containing a nitrogen atom.
<4> The positive type according to any one of <1> to <3>, in which the basic group is a group having a tertiary amino group, a nitrogen-containing aliphatic ring, or a nitrogen-containing aromatic ring. Original planographic printing plate.
<5> The positive lithographic printing plate precursor as described in any one of <1> to <4>, wherein the basic group is a group having a nitrogen-containing aliphatic ring or a group having a nitrogen-containing aromatic ring.
<6> The positive lithographic printing plate precursor as described in any one of <1> to <5>, wherein the basic group is a group having a piperidine ring.

<7> The ratio of the number N _{B of} basic groups of the binder polymer to the number N _{A of} acid groups of the acidic compound is N _B /N _A =1/1 to 40. The positive lithographic printing plate precursor as described in any one of the above.
<8> The ratio of the number N _{B of} basic groups of the binder polymer to the number N _{A of} acid groups of the acidic compound is N _B /N _A =1/1 to 30. The positive lithographic printing plate precursor as described in any one of the above.

<9> The positive lithographic printing plate precursor as described in any one of <1> to <8>, in which the acidic compound contains a polycarboxylic acid compound.
<10> The positive type lithographic printing plate precursor as described in any one of <1> to <9>, wherein the acidic compound has a molecular weight of 100 to 1,000.

<11> An exposure step of image-exposing the positive planographic printing plate precursor according to any one of <1> to <10>, and
And a developing step of developing the exposed positive lithographic printing plate precursor using a developer having a pH of 10.0 or less, in this order.
Method of making a lithographic printing plate.

According to the embodiments of the present disclosure, there are provided a positive planographic printing plate precursor excellent in ablation suppression property, and a method for producing a planographic printing plate using the positive planographic printing plate precursor.

The details of the present disclosure will be described below. The description of the components described below may be made based on the representative embodiment of the present disclosure, but the present disclosure is not limited to such an embodiment.
In addition, in this indication, "-" which shows a numerical range is used in the meaning including the numerical value described before and after that as a lower limit and an upper limit.
In the numerical ranges described stepwise in the present disclosure, the upper limit or the lower limit described in one numerical range may be replaced with the upper limit or the lower limit of the numerical range described in other stages. .. Further, in the numerical range described in the present disclosure, the upper limit value or the lower limit value of the numerical range may be replaced with the value shown in the examples.
Further, in the present disclosure, the amount of each component in the composition is the total amount of the corresponding substances present in the composition, unless a plurality of substances corresponding to each component are present in the composition. Means
In addition, in the notation of a group (atomic group) in the present disclosure, the notation that does not indicate substituted or unsubstituted includes not only those having no substituent but also those having a substituent. For example, an “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 disclosure, “(meth)acrylic” is a term used as a concept including both acryl and methacryl, and “(meth)acryloyl” is a term used as a concept including both acryloyl and methacryloyl. is there.
Further, in the present disclosure, with respect to the notation of the group in the compound represented by the formula, when the term "substituted" or "unsubstituted" is not mentioned, and when the group can further have a substituent, there is no particular limitation. As long as the group includes not only an unsubstituted group but also a group having a substituent. For example, in the formula, if “R represents an alkyl group, an aryl group or a heterocyclic group” is described, “R represents an unsubstituted alkyl group, a substituted alkyl group, an unsubstituted aryl group, a substituted aryl group, an unsubstituted group. "Represents a heterocyclic group or a substituted heterocyclic group".
In addition, the term “process” in the present disclosure is included in this term as long as the intended purpose of the process is achieved, not only when it is an independent process but also when it cannot be clearly distinguished from other processes. Be done.
Moreover, in this indication, "mass %" and "weight%" are synonymous, and "mass part" and "weight part" are synonymous.
Furthermore, in the present disclosure, a combination of two or more preferable aspects is a more preferable aspect.
In addition, the weight average molecular weight (Mw) and the number average molecular weight (Mn) in the present disclosure use columns of TSKgel GMHxL, TSKgel G4000HxL, and TSKgel G2000HxL (both manufactured by Tosoh Corp.) unless otherwise specified. The gel permeation chromatography (GPC) analyzer was used to detect the solvent THF (tetrahydrofuran) with a differential refractometer, and the molecular weight was calculated using polystyrene as a standard substance.
In the present disclosure, the total solid content refers to the total mass of components in the composition or layer excluding volatile components such as solvents.
In the present disclosure, the term “lithographic printing plate precursor” includes not only the lithographic printing plate precursor but also the discarded plate precursor. In addition, the term "lithographic printing plate" includes not only a lithographic printing plate precursor prepared through the operations such as exposure and development, but also a discarded plate, if necessary. In the case of a waste original plate, the operations of exposure and development are not always necessary. The waste plate is a planographic printing plate precursor to be attached to a plate cylinder that is not used, for example, when printing a part of the paper surface in a single color or two colors in color newspaper printing.

In the present disclosure, the “main chain” represents the relatively longest binding chain in the molecule of the polymer compound forming the resin, and the “side chain” represents an atomic group branched from the main chain.
In the present disclosure, for example, having an acid group in a side chain includes a mode in which an acid group is directly bonded to the main chain. That is, even when the acid group is a side group (pendant group), such as a case where a carboxy group (—C(═O)OH) is directly bonded to the main chain, a mode having an acid group in the side chain is obtained. included.
Hereinafter, the present disclosure will be described in detail.

≪Positive lithographic printing plate precursor≫
The positive lithographic printing plate precursor according to the present disclosure has a support and an image recording layer formed on the support, and the image recording layer has a binder polymer having a structural unit having a basic group (hereinafter, specified Also referred to as a binder polymer), an acidic compound having two or more acid groups and having a molecular weight of 10,000 or less (hereinafter, also referred to as a specific acidic compound), and an infrared absorber.
Hereinafter, the positive planographic printing plate precursor according to the present disclosure is also simply referred to as “planographic printing plate precursor”.
In the lithographic printing plate precursor according to the present disclosure, the mechanism by which the occurrence of ablation during exposure is suppressed is not clear, but it is presumed as follows.

In the positive lithographic printing plate precursor according to the present disclosure, in the image recording layer, the basic group of the binder polymer and the acid group of the acidic compound form a salt, whereby the image recording layer becomes stronger, It is presumed that volatilization of components in the image recording layer at the time of exposure is suppressed and the ablation suppression property is excellent.
Furthermore, it is presumed that the presence of the salt formed in the image recording layer strengthens the image recording layer and increases the mechanical strength, so that the printing durability is also excellent.
The salt formed by the basic group of the binder polymer and the acid group of the acidic compound is decomposed when heat is applied. Therefore, in the non-exposed portion of the image forming layer, the penetration of the developer is suppressed by the presence of the salt, and in the exposed portion, the salt formed by the heat of exposure is thermally decomposed, and an acid group appears to the developer. It is presumed that the solubility is improved and the excellent developability is exhibited. As a result, it is presumed that the difference in solubility between the exposed portion and the unexposed portion in the image forming layer (so-called development discrimination) becomes large.

Hereinafter, details of each component of the positive planographic printing plate precursor according to the present disclosure will be described.

<Image recording layer>
The lithographic printing plate precursor according to the present disclosure has an image recording layer containing a specific binder polymer, a specific acidic compound, and an infrared absorber.

[Specific binder polymer]
The specific binder polymer may be an addition polymerization type resin or a polycondensation type resin as long as it has a constitutional unit having a basic group. From the viewpoint of printing durability and ease of production, the specific binder polymer is preferably an addition polymerization type resin, more preferably a resin obtained by polymerizing an ethylenically unsaturated compound, and an acrylic resin. Is particularly preferable.
Examples of addition-polymerization type resins include styrene resins and styrene-acrylic resins in addition to the above acrylic resins.
The acrylic resin is preferably a resin in which the content of the structural unit formed by the (meth)acrylic compound is 50% by mass or more based on the total mass of the resin.

(Base group)
The basic group contained in the specific binder polymer is not particularly limited and is preferably a group having a nitrogen atom such as an amino group from the viewpoint of ablation suppression property, printing durability, and developability, and a tertiary amino group. More preferably a group (excluding nitrogen-containing ring), a group having a nitrogen-containing aliphatic ring, or a group having a nitrogen-containing aromatic ring, a group having a nitrogen-containing aliphatic ring, or a nitrogen-containing aromatic ring. A group having a piperidine ring is more preferable, and a group having a piperidine ring is particularly preferable.
The group having a piperidine ring, which is a preferred example of a group having a nitrogen-containing aliphatic ring, is preferably a group having a hindered amine structure, and, for example, if it is a monovalent group, 1, 2, 2, 6, A 6-pentamethylpiperidyl group or a 2,2,6,6-tetramethylpiperidyl group is particularly preferable.
Examples of the group having a nitrogen-containing aromatic ring include a group obtained by removing one hydrogen atom from a pyridine ring (that is, a pyridyl group) and the like.
Further, the tertiary amino group is preferably a dialkylamino group. Here, the alkyl group substituting the amino group is preferably an alkyl group having 1 to 5 carbon atoms, and specific examples thereof include a methyl group, an ethyl group and an isopropyl group.

(Basic pKaH)
From the viewpoint of developability, the basic group pKaH is preferably 4 or more, more preferably 5 or more, and further preferably 8 or more.
The upper limit of pKaH of the basic group is not particularly limited, but is preferably 12 or less, more preferably 9 or less.
The base group pKaH means the pKa of an acid conjugated to the base group.
The pKaH in the present disclosure is calculated using ACD/Labs software Ver 8.0 for Microsoft windows ACD/pKa DB ver 8.07 manufactured by Advanced Chemistry Development.

(ClogP value of a structural unit having a basic group)
The ClogP value of the structural unit having a basic group is preferably -1.0 to 10.0, and is 1.0 to 5.0, from the viewpoint of developability, printing durability, and ink receptivity. More preferably, 2.0-4.0 is still more preferable.
The ClogP value is a value obtained by calculating the common logarithm logP of the partition coefficient P between 1-octanol and water. Known methods and software can be used for calculating ClogP values, but unless otherwise specified, the ClogP program incorporated in ChemBioDraw Ultra 12.0 of Cambridge soft Co. is used in the present disclosure.
In addition, in the calculation of the ClogP value, the connecting site (that is, the following *) of the structural unit (preferably a monomer unit) having a base group is replaced with a hydrogen atom.
For example, when calculating the ClogP value of the structural unit UA-1 below, the ClogP value is calculated after conversion into the structure UA′-1 below.

(Base number of specific binder polymer)
The base value of the specific binder polymer is preferably 1.4 meq/g to 2.0 meq/g, more preferably 1.5 meq/g to 1.9 meq/g, and further preferably 1.6 meq/g to 1.8 meq/g. preferable.
The base number of the specific binder polymer means the base number determined by the perchloric acid method defined by JIS K 2501:2003. The base number is obtained as the number of milligrams (mg) of potassium hydroxide equivalent to hydrochloric acid or perchloric acid required for neutralizing all the basic components contained in 1 g of the specific binder polymer.

The specific binder polymer, as a constitutional unit having a basic group, has the following formula (1), the following formula (2), or the following formula (3) from the viewpoint of ablation suppression property, developability, image area retention property, and printing durability. ) It is preferable to have a structural unit represented by The specific binder polymer particularly preferably has a structural unit represented by the following formula (1) for the same reason as above.

In formulas (1) to (3), R ¹ represents a hydrogen atom or a methyl group, X ¹ represents a single bond, an ester bond or an amide bond, and L ^{1 to} L ⁴ each independently represent a single bond or a divalent group. , Base ¹ and Base ² each independently represent a monovalent base group, Base ³ represents a divalent base group, and Y ^{1 to} Y ⁴ each independently represent -O- or -NR-. R represents a hydrogen atom or an alkyl group, and A ¹ represents a trivalent linking group. A ¹ or L ² and Base ² may combine to form a ring, or at least one of L ³ and L ⁴ and Base ³ may combine to form a ring, and L ³ and L ⁴ And may combine with each other to form a ring.

First, the formula (1) will be described.
In formula (1), R ¹ represents a hydrogen atom or a methyl group.
In formula (1), X ¹ represents a single bond, an ester bond (—C(═O)O—) or an amide bond (—C(═O)NH—, and is preferably an ester bond or an amide bond, More preferably, it is an ester bond.
When X ¹ represents an ester bond, the carbon atom in the ester bond is preferably bonded to the main chain side of the specific binder polymer.
Further, when X ¹ represents an amide bond, it is preferable that the carbon atom in the amide bond is bonded to the main chain side of the specific binder polymer.
In the formula (1), L ¹ represents a single bond or a divalent linking group, and a single bond, or an optionally substituted ether bond (—O—) or —NHC(═O)NH— It is preferably a valent hydrocarbon group, more preferably a single bond, a divalent hydrocarbon group, or a divalent hydrocarbon group having -NHC(=O)NH- inside, a single bond, A divalent aliphatic saturated hydrocarbon group or a divalent aliphatic saturated hydrocarbon group having -NHC(=O)NH- inside is more preferable. When L ¹ represents a divalent hydrocarbon group or a hydrocarbon group having —NHC(═O)NH— therein, the number of carbon atoms in L ¹ (also referred to as “the number of carbon atoms”) is 2 or more. It is preferable that it is 2 to 10, more preferably 2 to 12, and further preferably 2 to 12.
In the formula (1), Base ¹ represents a monovalent base group, preferably a tertiary amino group, a group having a nitrogen-containing aliphatic ring, or a group having a nitrogen-containing aromatic ring, and more preferably Aspects and particularly preferable aspects are as described in the above-mentioned section "-base group-".

In formula (2), Y ¹ and Y ² each independently represent —O— or —NH—, and —O— is preferred.
In formula (2), A ¹ represents a trivalent linking group, preferably a trivalent hydrocarbon group.
The number of carbon atoms in the trivalent linking group for A ¹ is preferably 2-8, more preferably 3-5.
In formula (2), L ² represents a single bond or a divalent linking group, preferably a single bond or a divalent hydrocarbon group. When L ² represents a divalent hydrocarbon group, the number of carbon atoms in L ¹ is preferably 1 to 3.
In Formula (2), Base ² represents a monovalent base group, and is preferably a tertiary amino group, a group having a nitrogen-containing aliphatic ring, or a group having a nitrogen-containing aromatic ring, and more preferably Aspects and particularly preferable aspects are as described in the above-mentioned section of -base group-.
In formula (2), A ¹ or L ² and Base ² may combine to form a ring, and examples of the ring formed include a piperidine ring and a pyridine ring.

In formula (3), Y ³ and Y ⁴ each independently represent —O— or —NH—, and —O— is preferred.
In formula (3), L ³ and L ⁴ represent a single bond or a divalent linking group, and are preferably a single bond or a divalent hydrocarbon group. When L ³ and L ⁴ represent a divalent hydrocarbon group, the carbon number of L ³ and L ⁴ is preferably 1-5, more preferably 1-3.
In the formula (3), Base ³ represents a divalent base group, preferably a tertiary amino group, a group having a nitrogen-containing aliphatic ring, or a group having a nitrogen-containing aromatic ring, and a nitrogen-containing group. A group having an aliphatic ring (in particular, a group having a hindered amine structure) is preferable.
In Formula (3), at least one of L ³ and L ⁴ and Base ³ may combine to form a ring, or L ³ and L ⁴ may combine to form a ring. Examples of the ring formed by combining at least one of L ³ and L ⁴ and Base ³ include a piperidine ring and a piperazine ring. Examples of the ring formed by combining L ³ and L ⁴ include a piperidine ring and a piperazine ring.

Specific examples of the structural unit having a basic group are shown below, but the structural unit having a basic group is not limited thereto.

The specific binder polymer may have one type of structural unit having a basic group, or may have two or more types.
The content of the constitutional unit having a basic group (preferably the constitutional unit represented by the formula (1), the formula (2), or the formula (3)) is from the viewpoint of image area retention and printing durability. It is preferably 5% by mass to 70% by mass, more preferably 10% by mass to 60% by mass, and further preferably 15% by mass to 50% by mass with respect to the total mass of the specific binder polymer. , 25 mass% to 50 mass% are particularly preferable.

The method of introducing the structural unit having a basic group is not particularly limited, and a monomer component that can be the structural unit described above (for example, a (meth)acrylate compound having a basic group, a (meth)acrylamide compound having a basic group, a base) A method of polymerizing or polycondensing a diamine compound having a group, a diol compound having a basic group, and the like) is preferable.

(Other units)
The specific binder polymer preferably further contains other constitutional units.
When the specific binder polymer is an addition-polymerization type resin, examples of the other structural unit include a structural unit formed by a (meth)acrylate compound, (meth)acrylamide, benzyl (meth)acrylate, a styrene compound, or the like. , A structural unit formed of a (meth)acrylate compound is preferable, and a structural unit formed of a (meth)acrylate compound having no hydrophilic group is more preferable from the viewpoint of image area retention and printing durability. preferable.

The specific binder polymer, which is an addition-polymerizable resin, may have one type of the above-mentioned other structural units alone, or may have two or more types.
The content of the structural unit formed by the (meth)acrylate compound which is the other structural unit is preferably 30% by mass to 90% by mass with respect to the total mass of the specific binder polymer which is the addition polymerization type resin. It is more preferably 40% by mass to 90% by mass.

The (meth)acrylate compound may be a monofunctional (meth)acrylate compound having one (meth)acryloxy group in one molecule and may have two or more (meth)acryloxy groups in one molecule. Although it may be a polyfunctional (meth)acrylate compound, a monofunctional (meth)acrylate compound is preferable from the viewpoint of developability.
From the viewpoint of ink receptivity and scratch resistance, the (meth)acrylate compound is preferably a monofunctional (meth)acrylate compound having no hydrophilic group.
Examples of the monofunctional methacrylic acid ester compound having no hydrophilic group include (meth)acrylic acid alkyl ester having no hydrophilic group. The (meth)acrylic acid alkyl ester having no hydrophilic group preferably has a chain or cyclic alkyl group as the alkyl group. Further, this alkyl group may have a substituent other than the hydrophilic group.
Among the above, methacrylic acid alkyl ester having an alkyl group having 1 to 12 carbon atoms is preferable from the viewpoint of image area retention and printing durability.
Specific examples of the methacrylic acid alkyl ester having an alkyl group having 1 to 12 carbon atoms include methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, 2-ethylhexyl methacrylate and the like.
Of these, methyl methacrylate is preferable.

When the specific binder polymer is a polycondensation type resin, as the polycondensation type resin, a resin having any one of a urea bond, a urethane bond and an amide bond in its main chain is preferably used.
Among them, from the viewpoint of printing durability, the specific binder polymer which is a polycondensation type resin is more preferably a resin having one bond of a urea bond and a urethane bond in the main chain, and a urethane bond in the main chain. It is more preferable that the resin has
Further, the specific binder polymer which is a polycondensation type resin is preferably polyurea, polyurethane, polyurethane polyurea or polyamide, more preferably polyurea, polyurethane or polyurethane polyurea.

In the present disclosure, the “urea bond” is represented by —NR ^U1 C(═O)NR ^U2 —. In the present disclosure, R ^U1 and R ^U2 are each independently a hydrogen atom or an alkyl group having 1 to 10 carbon atoms (methyl group, ethyl group, propyl group, isopropyl group, tert-butyl group, pentyl group, hexyl group, And a hydrogen atom or an alkyl group having 5 or less carbon atoms is preferable.

The urea bond may be formed by any means, but it can be obtained by reacting an isocyanate compound with an amine compound.
Also, like 1,3-bis(2-aminoethyl)urea, 1,3-bis(2-hydroxyethyl)urea, 1,3-bis(2-hydroxypropyl)urea, etc., a hydroxy group at the terminal or A urea compound substituted with an alkyl group having an amino group may be synthesized as a raw material.

The above-mentioned isocyanate compound used as a raw material can be used without particular limitation as long as it is a polyisocyanate compound having two or more isocyanate groups in the molecule, but a diisocyanate compound is preferable.
Examples of the polyisocyanate compound include 1,3-bis(isocyanatomethyl)cyclohexane, isophorone diisocyanate, trimethylene diisocyanate, tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, 1,3-cyclopentane diisocyanate, 9H-fluorene. -2,7-diisocyanate, 9H-fluoren-9-one-2,7-diisocyanate, 4,4'-diphenylmethane diisocyanate, 1,3-phenylene diisocyanate, tolylene-2,4-diisocyanate, Tolylene-2,6-diisocyanate, 1,3-bis(isocyanatomethyl)cyclohexane, 2,2-bis(4-isocyanatophenyl)hexafluoropropane, 1,5-diisocyanatonaphthalene and the like can be mentioned. ..

As the above-mentioned amine compound used as a raw material, any polyamine compound having two or more amino groups in the molecule can be used without particular limitation, but a diamine compound is preferable.
Examples of the polyamine compound include 2,7-diamino-9H-fluorene, 3,6-diaminoacridine, acriflavine, acridine yellow, 2,2-bis(4-aminophenyl)hexafluoropropane, 4,4′-diamino. Benzophenone, bis(4-aminophenyl) sulfone, 4,4'-diaminodiphenyl ether, bis(4-aminophenyl) sulfide, 1,1-bis(4-aminophenyl)cyclohexane, 4,4'-diaminodiphenylmethane, 3 ,3'-diaminodiphenylmethane, 3,3'-diaminobenzophenone, 4,4'-diamino-3,3'-dimethyldiphenylmethane, 4-(phenyldiazenyl)benzene-1,3-diamine, 1,5-diaminonaphthalene , 1,3-phenylenediamine, 2,4-diaminotoluene, 2,6-diaminotoluene, 1,8-diaminonaphthalene, 1,3-diaminopropane, 1,3-diaminopentane, 2,2-dimethyl-1 ,3-propanediamine, 1,5-diaminopentane, 2-methyl-1,5-diaminopentane, 1,7-diaminoheptane, N,N-bis(3-aminopropyl)methylamine, 1,3-diamino 2-Propanol, diethylene glycol bis(3-aminopropyl) ether, m-xylylenediamine, tetraethylenepentamine, 1,3-bis(aminomethyl)cyclohexane, benzoguanamine, 2,4-diamino-1,3,5 -Triazine, 2,4-diamino-6-methyl-1,3,5-triazine, 6-chloro-2,4-diaminopyrimidine, 2-chloro-4,6-diamino-1,3,5-triazine, etc. Is mentioned.
Further, the above-mentioned diamine compound having an acid group can also be preferably used.
You may synthesize|combine polyisocyanate by making phosgene or triphosgene etc. react with these polyamines, and may be used as a raw material.

In the present disclosure, “urethane bond” is represented by —OC(═O)NR ^U3 —. Here, R ^U3 represents a hydrogen atom or an alkyl group having 1 to 10 carbon atoms (methyl group, ethyl group, propyl group, isopropyl group, tert-butyl group, pentyl group, hexyl group, cyclohexyl group, etc.), and hydrogen. An atom or an alkyl group having 5 or less carbon atoms is preferable, and a hydrogen atom or a methyl group is more preferable.

The urethane bond may be formed by any means, but can be obtained by reacting an isocyanate compound with a compound having a hydroxy group.
The isocyanate compound used as a raw material is preferably a polyisocyanate compound having two or more isocyanate groups in the molecule, and more preferably a diisocyanate compound. Examples of the polyisocyanate compound include the polyisocyanate compounds mentioned as the raw materials for forming the urea bond.
Examples of the compound having a hydroxy group used as a raw material include a polyol compound, an aminoalcohol compound, an aminophenol compound, an alkylaminophenol compound and the like, but a polyol compound or an aminoalcohol compound is preferable.
The polyol compound is a compound having at least two or more hydroxy groups in the molecule, and is preferably a diol compound. Further, it may have an ester bond or an ether bond in the molecule. Examples of the polyol compound include ethylene glycol, propylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol and 1,9. -Nonanediol, 1,10-decanediol, neopentyl glycol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, 1,4-cyclohexanedimethanol, pentaerythritol, 3-methyl-1,5-pentanediol, poly( Examples thereof include ethylene adipate), poly(diethylene adipate), poly(propylene adipate), poly(tetramethylene adipate), poly(hexamethylene adipate), and poly(neopenethylene adipate).
Further, the above-mentioned diol compound having an acid group can also be preferably used.
The amino alcohol compound is a compound having an amino group and a hydroxy group in the molecule and may further have an ether bond in the molecule. Examples of amino alcohols include amino ethanol, 3-amino-1-propanol, 2-(2-aminoethoxy)ethanol, 2-amino-1,3-propanediol, 2-amino-2-methyl-1,3- Propane diol, 1,3-diamino-2-propanol, etc. can be mentioned.

The amide bond may be formed by any means, but can be obtained by the reaction of a carboxylic acid chloride and an amine compound.
Examples of the amine compound include the polyamine compounds listed as the raw materials for forming the urea bond, and the diamine compounds having an acid group described above can also be suitably used.
Examples of the carboxylate compound include a carboxylic acid halide compound and a carboxylic acid ester compound, and examples thereof include CL-1 to CL-10 below.

The specific binder polymer which is a polycondensation type resin preferably has an alkyleneoxy group, and more preferably has an alkyleneoxy group in the main chain.
According to the above aspect, a lithographic printing plate precursor having excellent image forming properties of the lithographic printing plate obtained and excellent printing durability of the lithographic printing plate obtained can be obtained.
The alkyleneoxy group is preferably an alkyleneoxy group having 2 to 10 carbon atoms, more preferably an alkyleneoxy group having 2 to 8 carbon atoms, further preferably an alkyleneoxy group having 2 to 4 carbon atoms, an ethyleneoxy group, or , A propyleneoxy group is particularly preferable.
The specific binder polymer preferably has a polyalkyleneoxy group, and more preferably has a polyalkyleneoxy group in its main chain.
As the polyalkyleneoxy group, a polyalkyleneoxy group having a repeating number of 2 to 50 is preferable, a polyalkyleneoxy group having a repeating number of 2 to 40 is more preferable, and a polyalkyleneoxy group having a repeating number of 2 to 30 is further preferable.
The preferred carbon number of the repeating unit of the polyalkyleneoxy group is the same as the preferred carbon number of the alkyleneoxy group.
The method for introducing the alkyleneoxy group or the polyalkyleneoxy group is not particularly limited, but it is preferably introduced by a (meth)acrylate compound, a diol compound, a diamine compound, a diisocyanate compound or the like having an alkyleneoxy group or a polyalkyleneoxy group. can do.

From the viewpoint of printing durability of the lithographic printing plate obtained, the weight average molecular weight of the specific binder polymer may be 5,000 or more, preferably 10,000 to 200,000, and 10,000 to 100, 2,000 is more preferable, and 12,000 to 50,000 is particularly preferable.

The image recording layer may contain one specific binder polymer or two or more specific binder polymers.
The content of the specific binder polymer in the image recording layer is preferably 10% by mass to 99% by mass with respect to the total mass of the image recording layer from the viewpoints of ablation suppression property, image part retaining property, and printing durability. , 20% by mass to 95% by mass, more preferably 30% by mass to 90% by mass.

The specific binder polymer is produced, for example, by a known method. For example, a specific binder polymer can be obtained as a polymer by using a composition containing a monomer used to form each structural unit and a known polymerization initiator and applying energy such as heating or exposure. The composition may further contain known additives.
The detailed conditions for applying the energy may be determined with reference to a known document.

Specific examples of the specific binder polymer used in the present disclosure preferably include those used in Examples described below, but it goes without saying that the specific binder polymer is not limited thereto.

[Specific acidic compound]
The specific acidic compound is not particularly limited as long as it is a compound having two or more acid groups and a molecular weight of 10,000 or less.
The specific acidic compound is preferably a compound having 2 to 8 acid groups, and is a compound having 2 to 6 acid groups from the viewpoint of ablation suppression property, image part retaining property, and printing durability. It is preferable.
The molecular weight of the specific acidic compound may be smaller than the weight average molecular weight of the specific binder polymer from the viewpoint of ablation suppression property, image area retention property, and printing durability, and from the viewpoint of developability, it is less than 5,000. It is preferably 100 to 3,000, more preferably 100 to 1,000.

(Acid group)
The acid group of the specific acidic compound is not particularly limited, and an acid group having a pKa of 9 or less is preferable.
Specific examples of the acid group include a carboxy group, a sulfo group, a phosphonic acid group, and a phosphoric acid group, but from the viewpoint of ablation suppression property, image part retention property and printing durability, a carboxy group, a sulfo group, or A phosphoric acid group is more preferable, and a carboxy group is particularly preferable.
That is, the specific acidic compound is preferably a polyvalent carboxylic acid compound having two or more carboxy groups.

(PKa of acid group)
As described above, the pKa of the acid group is preferably 9 or less, more preferably 7 or less, and from the viewpoint of developability, it is more preferably 6 or less and 5.5 or less. More preferably.
The lower limit of pKa of the acid group is not particularly limited, but is preferably −5 or more, more preferably 0 or more, and further preferably 2 or more.
Particularly, the pKa of the acid group is particularly preferably 4.0 to 5.0.
The pKa in the present disclosure is calculated using ACD/Labs software Ver 8.0 for Microsoft windows ACD/pKa DB ver 8.07 manufactured by Advanced Chemistry Development.

(ClogP value of characteristic acidic compound)
The ClogP value of the characteristic acidic compound is preferably −8.0 to 5.0, more preferably 0.0 to 4.0, from the viewpoint of developability, printing durability and ink receptivity. , 1.0 to 3.4 is more preferable.
The ClogP value of the characteristic acidic compound is obtained by the same method as the ClogP value of the structural unit having a basic group described above. In the structural unit having a basic group, the calculation was performed by converting to the above-mentioned structure UA′-1 and the like, but in the specific acidic compound, the ClogP value is calculated for the entire specific acidic compound.

(Acid value)
The acid value of the specific acidic compound is preferably 1.0 meq/g to 16.0 meq/g, and more preferably 1.5 meq/g to 15.0 meq/g.
The acid value of the specific binder polymer is represented by the number of moles of potassium hydroxide required to neutralize 1 g of the specific binder polymer, and the value obtained by the measurement method according to JIS standard (JIS K 0070:1992) should be used. You can

Specific examples of the polycarboxylic acid compound, which is a preferred embodiment of the specific acidic compound, are shown below, but the specific acidic compound is not limited thereto. In addition, "Ac" in the specific examples represents an acetyl group.

The image recording layer may contain one specific acidic compound or two or more specific acidic compounds.
The content of the specific acidic compound in the image recording layer is preferably 5% by mass to 90% by mass with respect to the total mass of the image recording layer from the viewpoints of ablation suppression property, image area retention property and printing durability. It is more preferably 10% by mass to 80% by mass, and further preferably 20% by mass to 70% by mass.

The mass ratio of the content M _P of the specific binder polymer and the content M _C of the specific acidic compound in the image recording layer is M _P /M _C =from the viewpoints of ablation suppression property, image area retention property and printing durability. It is preferably 0.1 to 10, more preferably M _P /M _C =0.2 to 5, further preferably M _P /M _C =0.5 to 2, and M _P / It is particularly preferable that M _C =0.7 to 1.5.

The ratio (N _B /N _A ) of the number N _{B of the} basic groups contained in the specific binder polymer contained in the image recording layer and the number N _A of the acidic groups contained in the specific acidic compound is ablation suppression property, image part retention property, and from the viewpoint of printing _durability, it is preferably _{N B / N a = 1 /} 1.1~40, more preferably _{N B / N a = 1 /} 1.1~30, N B / It is more preferable that N _A =1/2 to 15, and it is particularly preferable that N _B /N _A =1/3 to 10.
In addition, from the viewpoint of further enhancing the ablation suppression property, the image part retaining property, and the printing durability, it is preferable that N _B /N _A =1/4 or more, and N _B /N _A =1/5 or more. More preferably. _The upper limit value of _{N B / N A, N B} / N A = 1/8 is preferred.
Further, the number of the basic groups contained in the specific binder polymer contained in the image recording layer is smaller than the number of acid groups contained in the specific acidic compound from the viewpoints of ablation suppression property, image part retaining property and printing durability. Is preferred.

[Infrared absorber]
The infrared absorbent is not particularly limited as long as it is a dye that absorbs infrared light and generates heat, and various dyes known as infrared absorbents can be used.
As the infrared absorber that can be used in the present disclosure, commercially available dyes and known ones described in the literature (for example, “Handbook of Dyes” edited by the Society of Synthetic Organic Chemistry, published in 1970) can be used. Specific examples of the infrared absorbing agent include dyes such as azo dyes, metal complex salt azo dyes, pyrazolone azo dyes, anthraquinone dyes, phthalocyanine dyes, carbonium dyes, quinone imine dyes, methine dyes and cyanine dyes. In the present disclosure, among these dyes, those that absorb at least infrared light or near infrared light are preferable in that they are suitable for utilizing a laser that emits infrared light or near infrared light for exposure, and cyanine Dyes are particularly preferred.

Examples of dyes that absorb at least infrared light or near infrared light include JP-A-58-125246, JP-A-59-84356, JP-A-59-202829, and JP-A-60-78787. Cyanine dyes described in JP-A-58-173696, JP-A-58-181690 and JP-A-58-194595, and methine dyes described in JP-A-58-194595 and JP-A-58 -112793, JP-A-58-224793, JP-A-59-48187, JP-A-59-73996, JP-A-60-52940, and JP-A-60-63744. Examples thereof include naphthoquinone dyes, squarylium dyes described in JP-A-58-112792, and cyanine dyes described in British Patent No. 434,875.
Further, as the dye, a near infrared absorption sensitizer described in US Pat. No. 5,156,938, a substituted arylbenzo(thio)pyrylium salt described in US Pat. No. 3,881,924, Trimethine thiapyrylium salt described in JP-A-57-142645 (US Pat. No. 4,327,169), JP-A-58-181051, JP-A-58-220143, JP-A-59-41363, and JP-A-58-41363. 59-84248, 59-84249, 59-146063 and 59-146061, pyrylium compounds, cyanine dyes described in JP-A-59-216146, U.S. Pat. The pentamethine thiopyrylium salt described in the specification of 4,283,475, and the pyrylium compounds disclosed in Japanese Patent Publication Nos. 5-13514 and 5-19702 are mentioned. As commercially available dyes, Epolight III-178, Epolight III-130, and Epolight III-125 manufactured by Eporin Co. are particularly preferably used.
Another particularly preferable example of the dye is a near infrared absorbing dye described as formula (I) or (II) in US Pat. No. 4,756,993.

Particularly preferred among these dyes are cyanine dyes, phthalocyanine dyes, oxonol dyes, squarylium dyes, pyrylium salts, thiopyrylium dyes, and nickel thiolate complexes. Furthermore, the cyanine dye represented by the following formula (a) is most preferable because it is excellent in stability and economy when used in the image recording layer in the present disclosure.

In formula (a), X ¹ represents a hydrogen atom, a halogen atom, a diarylamino group (—NPh ₂ ), X ² —L ¹ , or a group shown below. X ² represents an oxygen atom or a sulfur atom. L ¹ represents a hydrocarbon group having 1 to 12 carbon atoms, an aromatic ring having a hetero atom, or a hydrocarbon group having 1 to 12 carbon atoms and containing a hetero atom. In addition, a hetero atom here shows a nitrogen atom, a sulfur atom, an oxygen atom, a halogen atom, or a selenium atom.

In the above formula, Xa ⁻ is defined in the same manner as Za ⁻ described later, and ^Ra is a substituent selected from the group consisting of a hydrogen atom, an alkyl group, an aryl group, a substituted or unsubstituted amino group, and a halogen atom. Represents.

R ²¹ and R ²² each independently represent a hydrocarbon group having 1 to 12 carbon atoms. From the viewpoint of storage stability of the positive type lithographic printing plate precursor, R ²¹ and R ²² are preferably a hydrocarbon group having 2 or more carbon atoms, and further, R ²¹ and R ²² are bonded to each other to form a 5-membered ring. Or, it is particularly preferable to form a 6-membered ring.

Ar ¹ and Ar ^{2, which} may be the same or different, each represents an aromatic hydrocarbon group which may have a substituent. A benzene ring and a naphthalene ring are mentioned as a preferable aromatic hydrocarbon group. Moreover, as a preferable substituent, a C12 or less hydrocarbon group, a halogen atom, and a C12 or less alkoxy group are mentioned.
Y ¹¹ and Y ^{12, which} may be the same or different, each represents a sulfur atom or a dialkylmethylene group having 12 or less carbon atoms. R ²³ and R ^{24, which} may be the same or different, each represents a hydrocarbon group having 20 or less carbon atoms, which may have a substituent. Preferable substituents include an alkoxy group having 12 or less carbon atoms, a carboxyl group and a sulfo group.
R ²⁵ , R ²⁶ , R ²⁷ and R ^{28, which} may be the same or different, each represents a hydrogen atom or a hydrocarbon group having 12 or less carbon atoms. From the availability of raw materials, R ²⁵ , R ²⁶ , R ²⁷ and R ²⁸ are preferably hydrogen atoms.
Za ⁻ represents a counter anion. However, when the cyanine dye represented by the formula (a) has an anionic substituent in its structure and it is not necessary to neutralize the charge, Za ⁻ is not necessary. Preferred Za ⁻ is a halide ion, a perchlorate ion, a tetrafluoroborate ion, a hexafluorophosphate ion, and a sulfonate ion from the storage stability of the positive lithographic printing plate precursor, and particularly preferably, perchloric acid. An ion, a hexafluorophosphate ion, and an arylsulfonate ion.

Specific examples of the cyanine dye represented by formula (a) that can be preferably used include paragraphs 0017 to 0019 in JP 2001-133969 A, paragraphs 0012 to 0038 in JP 2002-40638 A, and JP 2002 A. The thing described in paragraphs 0012-0023 of 23360 gazette can be mentioned.
The cyanine dye A shown below is particularly preferable as the infrared absorber contained in the image recording layer.

The content of the infrared absorbent is preferably 0.01% by mass to 50% by mass, more preferably 0.1% by mass to 30% by mass, based on the total mass of the image recording layer. It is particularly preferable that the content is 0.0% by mass to 30% by mass. When the addition amount is 0.01% by mass or more, the sensitivity is high, and when the addition amount is 50% by mass or less, the uniformity of the layer is good and the durability of the layer is excellent.

[Other binder polymers]
The image recording layer in the present disclosure may further contain other binder polymer.
The other binder polymer is a resin that does not correspond to the specific binder polymer described above.
The image recording layer is selected from the group consisting of a phenol resin, a styrene-acrylonitrile copolymer, an acrylic resin, an acetal resin, and a resin having a urea bond, a urethane bond, or an amide bond in the main chain as the other binder polymer. It is preferable to further include at least one selected from the above.
The other binder polymer is preferably an alkali-soluble resin, more preferably a weak alkali-soluble resin.

-Phenolic resin-
The phenol resin used as the other binder polymer used in the present disclosure is preferably a phenol resin having a weight average molecular weight of more than 2,000. The phenol resin having a weight average molecular weight of more than 2,000 is a phenol resin containing phenol or a substituted phenol as a constitutional unit, preferably a novolak resin. The novolak resin is preferably used in the lithographic printing plate precursor because it causes a strong hydrogen bonding property in the unexposed area and some hydrogen bonds are easily released in the exposed area.
The novolac resin is not particularly limited as long as it contains phenols as a constituent unit in the molecule.
The novolac resin in the present disclosure is a resin obtained by a condensation reaction of phenol, a substituted phenol shown below, and an aldehyde, and specific examples of the phenol include phenol, isopropylphenol, t-butylphenol, Examples thereof include t-amylphenol, hexylphenol, cyclohexylphenol, 3-methyl-4-chloro-6-t-butylphenol, isopropylcresol, t-butylcresol and t-amylcresol. Preferred are t-butylphenol and t-butylcresol. In addition, examples of aldehydes include aliphatic and aromatic aldehydes such as formaldehyde, acetaldehyde, acrolein, and crotonaldehyde. Formaldehyde or acetaldehyde is preferable.
More specifically, examples of the novolac resin in the present disclosure include a condensation polymer of phenol and formaldehyde (phenol formaldehyde resin), a condensation polymer of m-cresol and formaldehyde (m-cresol formaldehyde resin), p. -Polymer of cresol and formaldehyde (p-cresol formaldehyde resin), polycondensate of m-/p-mixed cresol and formaldehyde (m-/p-mixed cresol-formaldehyde resin), phenol and cresol (m-, Condensation polymer of p- or m-/p-mixture) and formaldehyde (phenol/cresol (m-, p-, or m-/p-mixture) mixed formaldehyde resin), etc. Is mentioned.
Further, as the novolac resin, as described in US Pat. No. 4,123,279, an alkyl group having 3 to 8 carbon atoms such as t-butylphenol formaldehyde resin and octylphenol formaldehyde resin is further used. Examples thereof include condensation polymers of phenol and formaldehyde having a substituent.
Among these novolak resins, phenol formaldehyde resin and phenol/cresol mixed formaldehyde resin are particularly preferable.

The weight average molecular weight of the phenol resin is preferably more than 2,000 and 50,000 or less, more preferably 2,500 to 20,000, and particularly preferably 3,000 to 10,000. preferable. The dispersity (weight average molecular weight/number average molecular weight) is preferably 1.1 to 10.
The number average molecular weight is a polystyrene equivalent number average molecular weight measured by gel permeation chromatography (GPC) when tetrahydrofuran (THF) is used as a solvent.
Such phenolic resins may be used alone or in combination of two or more.

-Acetal resin-
Moreover, as the acetal resin, a polymer compound including a structural unit represented by the following formula EV-1 and the following formula EV-2 can be given.

In formula EV-1 or formula EV-2, L represents a divalent linking group, x is 0 or 1, R ¹ represents an aromatic ring group or a heteroaromatic ring group having at least one hydroxy group, R ² and R ³ are each independently a hydrogen atom, a halogen atom, a linear or branched group which may have a substituent, or a cyclic alkyl group, a linear or branched group which may have a substituent, Alternatively, it represents a cyclic alkenyl group, an aromatic ring which may have a substituent, or a heteroaromatic ring which may have a substituent.

In Formula EV-1, R ¹ represents an aromatic ring or a heteroaromatic ring having at least one hydroxy group, and the hydroxy group may be at any of the ortho, meta and para positions with respect to the binding site with L. Good.
Preferable examples of the aromatic ring include phenyl group, benzyl group, tolyl group, o-, m-, p-xylyl group, naphthyl group, anthracenyl group, and phenanthrenyl group.
Preferred examples of the heteroaromatic ring include a furyl group, a pyridyl group, a pyrimidyl group, a pyrazoyl group, and a thiophenyl group.
These aromatic rings or heteroaromatic rings may have a substituent other than a hydroxyl group, and examples of the substituent include an alkyl group such as a methyl group and an ethyl group; an alkoxy group such as a methoxy group and an ethoxy group; an aryloxy group. Groups, thioalkyl groups, thioaryl groups, -SH, azo groups such as azoalkyl groups and azophenyl groups; thioalkyl groups, amino groups, ethenyl groups, alkenyl groups, alkynyl groups, cycloalkyl groups, aryl groups, heteroaryl groups, or hetero groups. Examples thereof include alicyclic groups.
R ¹ is preferably a hydroxyphenyl group having a hydroxy group or a hydroxynaphthyl group, and more preferably a hydroxyphenyl group.
Examples of the hydroxyphenyl group include 2-, 3-, or 4-hydroxyphenyl groups.
Examples of the hydroxynaphthyl group include 2,3-, 2,4-, or 2,5-dihydroxynaphthyl group, 1,2,3-trihydroxynaphthyl group, and hydroxynaphthyl group.
The hydroxyphenyl group or hydroxynaphthyl group may have a substituent, and preferable examples of the substituent include alkoxy groups such as methoxy group and ethoxy group.

In Formula EV-1, L represents a divalent linking group, an alkylene group, an arylene group, a heteroarylene group, -O-, -C(=O)-, -C(=O)O-, -C( =O)-NH-, -NH-C(=O)-, -NH-C(=O)-O-, -O-C(=O)-NH-, -NH-C(=O)-. NH-, -NH-C(=S)-NH-, -S(=O)-, -S(=O) _2- , -CH=N-, -NH-NH-, or a bond thereof. It is preferred to represent the groups represented.
The alkylene group, the arylene group, or the heteroarylene group may have a substituent, and as the substituent, an alkyl group, a hydroxy group, an amino group, a monoalkylamino group, a dialkylamino group, an alkoxy group, and , Phosphonic acid groups or salts thereof.
L is an alkylene group, an arylene group, or, more preferably heteroarylene _{group, -CH 2 -, - CH 2} -CH 2 -, - CH 2 -CH 2 -CH 2 -, or, phenylene group More preferably,

In Formula EV-2, R ² and R ³ may each independently have a hydrogen atom, a halogen atom, a linear or branched alkyl group which may have a substituent, or a cyclic alkyl group and a substituent. It represents a linear, branched, or cyclic alkenyl group, an aromatic ring that may have a substituent, or a heteroaromatic ring that may have a substituent.
As the alkyl group, a methyl group, an ethyl group, an n-propyl group, an n-butyl group, an n-pentyl group, an n-hexyl group, a chloromethyl group, a trichloromethyl group, an isopropyl group, an isobutyl group, an isopentyl group, a neopentyl group. , 1-methoxybutyl group, isohexyl group, cyclopropyl group, cyclobutyl group, cyclopentyl group, cyclohexyl group, and methylcyclohexyl group.
As the alkenyl group, an ethenyl group, n-propenyl group, n-butenyl group, n-pentenyl group, n-hexenyl group, isopropenyl group, isobutenyl group, isopentenyl group, neopentenyl group, 1-methylbutenyl group, isohexenyl group. Group, a cyclopentenyl group, a cyclohexenyl group, and a methylcyclohexenyl group.
A chlorine atom is mentioned as a halogen atom.
The aromatic ring preferably includes aryl groups such as phenyl group, benzyl group, tolyl group, o-, m-, p-xylyl group, naphthyl group, anthracenyl group, and phenanthrenyl group.
Examples of the heteroaromatic ring include a furyl group, a pyridyl group, a pyrimidyl group, a pyrazoyl group, and a thiophenyl group.
R ² and R ³ each independently represent a hydrogen atom, a chlorine atom or a methyl group, and more preferably a hydrogen atom.

Examples of the substituents on the alkyl group, alkenyl group, aromatic ring or heteroaromatic ring include alkoxy groups such as methoxy group and ethoxy group, thioalkyl groups, and mercapto groups.
The aromatic ring or heteroaromatic ring may have an azo group such as an aryloxy group, a thioaryl group, an azoalkyl group and an azoaryl group, or an amino group as a substituent.

The content of the structural unit represented by the formula EV-1 (however, converted as a monomer unit) is preferably 10 mol% or more, and 10 mol% to 55 mol% with respect to the total amount of the monomer unit in the polymer compound. Is more preferable, 15 mol% to 45 mol% is further preferable, and 20 mol% to 35 mol% is particularly preferable.
The content of the structural unit represented by the formula EV-2 (however, converted as a monomer unit) is preferably 15 mol% or more, and 15 mol% to 60 mol% with respect to the total amount of the monomer unit in the polymer compound. Is more preferable, 20 mol% to 50 mol% is further preferable, and 25 mol% to 45 mol% is particularly preferable.

Further, the total content of the constitutional unit represented by the formula EV-1 and the constitutional unit represented by the formula EV-2 (however, converted as monomer units) is the total amount of the monomer units in the polymer compound. On the other hand, 50 mol% to 90 mol% is preferable, 60 mol% to 80 mol% is more preferable, and 65 mol% to 75 mol% is further preferable.

The weight average molecular weight of the acetal resin is preferably 5,000 or more, more preferably 10,000 to 500,000, still more preferably 10,000 to 300,000.

The image recording layer may contain one kind of other binder polymer alone, or may contain two or more kinds thereof.
The content of the other binder polymer is preferably 1% by mass to 90% by mass, more preferably 5% by mass to 50% by mass, and more preferably 10% by mass to 30% by mass, based on the total mass of the specific binder polymer. It is particularly preferable that

[Acid generator]
The image recording layer in the present disclosure preferably contains an acid generator from the viewpoint of improving the sensitivity of the lithographic printing plate precursor obtained.
In the present disclosure, the acid generator is a compound that generates an acid by light or heat, and refers to a compound that decomposes to generate an acid by irradiation with infrared rays or heating at 100° C. or higher. The generated acid is preferably a strong acid having a pKa of 2 or less such as sulfonic acid and hydrochloric acid. The acid generated from the acid generator enhances the permeability of the developing solution into the exposed area of the positive lithographic printing plate precursor, and further improves the solubility of the image recording layer in the alkaline aqueous solution.
Examples of the acid generator preferably used in the image recording layer in the present disclosure include the acid generators described in paragraphs 0116 to 0130 of WO 2016/047392.
Above all, it is preferable to use an onium salt compound as the acid generator from the viewpoints of sensitivity and stability. The onium salt compound will be described below.
Examples of onium salt compounds that can be preferably used in the present disclosure include compounds known as compounds that generate an acid by being exposed to infrared rays and decomposed by the thermal energy generated from the infrared absorber upon exposure. Examples of onium salt compounds suitable for the present disclosure include known thermal polymerization initiators and compounds having an onium salt structure described below having a bond with a small bond dissociation energy from the viewpoint of sensitivity.
Examples of the onium salt preferably used in the present disclosure include known diazonium salts, iodonium salts, sulfonium salts, ammonium salts, pyridinium salts, azinium salts, and the like. Among them, triarylsulfonium or diaryliodonium sulfonates , Carboxylate, BF ₄ ⁻ , PF ₆ ⁻ , ClO ₄ ^{− and the} like are preferable.
Examples of onium salts that can be used as the acid generator in the present disclosure include onium salts represented by the following formulas (III) to (V).

In the above formula III, Ar ¹¹ and Ar ¹² each independently represent an aryl group having 20 or less carbon atoms which may have a substituent. When the aryl group has a substituent, a preferable substituent is a halogen atom, a nitro group, an alkyl group having 12 or less carbon atoms, an alkoxy group having 12 or less carbon atoms, or an aryloxy group having 12 or less carbon atoms. .. Z ^11- is a pair selected from the group consisting of a halide ion, a perchlorate ion, a tetrafluoroborate ion, a hexafluorophosphate ion, a sulfonate ion, and a sulfonate ion having a fluorine atom such as a perfluoroalkylsulfonate ion. It represents an ion and is preferably a perchlorate ion, a hexafluorophosphate ion, an aryl sulfonate ion, and a perfluoroalkyl sulfonic acid.
In the formula (IV), Ar ²¹ represents an optionally substituted aryl group having 1 to 20 carbon atoms. As a preferable substituent, a halogen atom, a nitro group, an alkyl group having 1 to 12 carbon atoms, an alkoxy group having 1 to 12 carbon atoms, an aryloxy group having 1 to 12 carbon atoms, an alkylamino group having 1 to 12 carbon atoms, Examples thereof include a dialkylamino group having 2 to 12 carbon atoms, an arylamino group having 6 to 12 carbon atoms, and a diarylamino group (the carbon numbers of two aryl groups are each independently 6 to 12). Z ²¹⁻ represents a counter ion having the same ^meaning as Z ¹¹⁻ .
In the formula (V), R ³¹ , R ^32, and R ³³ may be the same or different and each represents a hydrocarbon group having 1 to 20 carbon atoms which may have a substituent. Examples of preferable substituents include a halogen atom, a nitro group, an alkyl group having 1 to 12 carbon atoms, an alkoxy group having 1 to 12 carbon atoms, and an aryloxy group having 1 to 12 carbon atoms. Z ^31- represents a counter ion having the same ^meaning as Z ^11- .

Specific examples of the onium salt that can be preferably used in the image recording layer of the present disclosure are the same as the compounds described in paragraphs 0121 to 0124 of International Publication No. 2016/047392.

Further, as another example of the compounds represented by the above formulas (III) to (V), the compounds described as examples of the radical polymerization initiator in paragraphs 0036 to 0045 of JP 2008-195018 A can be used. Can be suitably used as the acid generator according to the present disclosure.

More preferable examples of the acid generator that can be used in the present disclosure include the following compounds (PAG-1) to (PAG-5).

When these acid generators are contained in the image recording layer in the present disclosure, these compounds may be used alone or in combination of two or more kinds.
The content of the acid generator is preferably 0.01% by mass to 50% by mass, more preferably 0.1% by mass to 40% by mass, and 0.5% by mass with respect to the total mass of the image recording layer. -30 mass% is more preferable. When the content is within the above range, the sensitivity, which is an effect of the addition of the acid generator, is improved, and the generation of the residual film in the non-image area is suppressed.

[Acid multiplying agent]
The image recording layer in the present disclosure may contain an acid multiplying agent. The acid multiplying agent in the present disclosure is a compound substituted with a residue of a relatively strong acid, and is a compound that is easily eliminated in the presence of an acid catalyst to newly generate an acid. That is, it decomposes by an acid-catalyzed reaction to generate an acid again. One or more acids are increased in one reaction, and the acid concentration is accelerated as the reaction progresses, so that the sensitivity is dramatically improved. The strength of the generated acid is preferably 3 or less as an acid dissociation constant (pKa), and more preferably 2 or less. When the acid dissociation constant is 3 or less, the elimination reaction by the acid catalyst is likely to occur.
Examples of the acid used for such an acid catalyst include dichloroacetic acid, trichloroacetic acid, methanesulfonic acid, ethanesulfonic acid, benzenesulfonic acid, p-toluenesulfonic acid, naphthalenesulfonic acid and phenylsulfonic acid.

The usable acid multiplying agent is the same as those described in paragraphs 0133 to 0135 of WO2016/047392.

The acid multiplying agent may be contained alone or in combination of two or more.
The content of the acid multiplying agent is preferably 0.01% by mass to 20% by mass, more preferably 0.01% by mass to 10% by mass, and 0.1% by mass to 5% based on the total mass of the image recording layer. Mass% is more preferable. When the content of the acid proliferating agent is within the above range, the effect of adding the acid proliferating agent is sufficiently obtained, the sensitivity is improved, and the reduction of the film strength of the image area is suppressed.

[Other additives]
The image recording layer in the present disclosure may contain a development accelerator, a surfactant, a printout agent, a colorant, a plasticizer, a wax agent, etc. as other additives.

-Development accelerator-
An acid anhydride, a phenol, or an organic acid may be added to the image recording layer in the present disclosure for the purpose of improving sensitivity.
As the acid anhydrides, cyclic acid anhydrides are preferable, and as the cyclic acid anhydrides, phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, which are described in US Pat. No. 4,115,128, 3,6-endooxytetrahydrophthalic anhydride, tetrachlorophthalic anhydride, maleic anhydride, chloromaleic anhydride, α-phenylmaleic anhydride, succinic anhydride, pyromellitic anhydride and the like can be used. Acetic anhydride etc. are mentioned as acyclic acid anhydride.
Examples of phenols include bisphenol A, 2,2′-bishydroxysulfone, p-nitrophenol, p-ethoxyphenol, 2,4,4′-trihydroxybenzophenone, 2,3,4-trihydroxybenzophenone, 4- Examples include hydroxybenzophenone, 4,4′,4″-trihydroxytriphenylmethane, 4,4′,3″,4″-tetrahydroxy-3,5,3′,5′-tetramethyltriphenylmethane. ..
Organic acids are described in JP-A-60-88942, JP-A-2-96755, and the like. Specifically, p-toluenesulfonic acid, dodecylbenzenesulfonic acid, p-toluenesulfinic acid, Ethyl sulfuric acid, phenylphosphonic acid, phenylphosphinic acid, phenyl phosphate, diphenyl phosphate, benzoic acid, isophthalic acid, adipic acid, p-toluic acid, 3,4-dimethoxybenzoic acid, phthalic acid, terephthalic acid, 4-cyclohexene Examples include -1,2-dicarboxylic acid, erucic acid, lauric acid, n-undecanoic acid, and ascorbic acid.
The content of the acid anhydride, phenols and organic acids is preferably 0.05% by mass to 20% by mass, more preferably 0.1% by mass to 15% by mass, based on the total mass of the image recording layer. 0.1% by mass to 10% by mass is particularly preferable.

-Surfactant-
The image-recording layer according to the present disclosure may contain a surfactant in order to improve the coatability at the time of forming the image-recording layer and to broaden the stability of processing under developing conditions. Examples of the surfactant include nonionic surfactants described in JP-A-62-251740 and JP-A-3-208514, JP-A-59-121044, and JP-A-4-13149. Ampholytic surfactants such as those described in JP-A No. 62-170950, JP-A No. 11-288093, JP-A No. 2003-57820, and the like. Examples thereof include monomer copolymers.
Specific examples of the nonionic surfactant include sorbitan tristearate, sorbitan monopalmitate, sorbitan trioleate, stearic acid monoglyceride, polyoxyethylene nonylphenyl ether and the like.
Specific examples of the amphoteric activator include alkyldi(aminoethyl)glycine, alkylpolyaminoethylglycine hydrochloride, 2-alkyl-N-carboxyethyl-N-hydroxyethylimidazolinium betaine, N-tetradecyl-N,N-betaine. Examples include molds (for example, trade name “Amorgen K”: manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.) and the like.
The proportion of the surfactant in the total mass of the image recording layer is preferably 0.01% by mass to 15% by mass, more preferably 0.01% by mass to 5% by mass, and 0.05% by mass to 2.0% by mass. % Is more preferable.

-Bakeout agent/colorant-
To the image recording layer in the present disclosure, a printout agent for obtaining a visible image immediately after heating by exposure and/or a dye or a pigment as a colorant can be added.
The print-out agent and the colorant are described in detail, for example, in paragraphs 0122 to 0123 of JP2009-229917A, and the compounds described therein can be applied to the present disclosure.
The content of the print-out agent and the colorant is preferably 0.01 to 10% by mass, more preferably 0.1 to 3% by mass, based on the total mass of the image recording layer.

-Plasticizer-
A plasticizer may be added to the image recording layer in the present disclosure in order to impart flexibility to the coating film. Examples of the plasticizer include butylphthalyl, polyethylene glycol, tributyl citrate, diethyl phthalate, dibutyl phthalate, dihexyl phthalate, dioctyl phthalate, tricresyl phosphate, tributyl phosphate, trioctyl phosphate, tetrahydrofurfuryl oleate, and Acrylic acid or methacrylic acid oligomers and polymers are used.
The content of the plasticizer is preferably 0.5% by mass to 10% by mass, and more preferably 1.0% by mass to 5% by mass, based on the total mass of the image recording layer.

-Wax agent-
The image recording layer in the present disclosure may contain a compound (that is, a wax agent) that lowers the coefficient of static friction of the surface for the purpose of imparting scratch resistance. Specific examples of the wax agent are described in US Pat. No. 6,117,913, JP2003-149799A, JP2003-302750A, or JP2004-12770A. Examples of such compounds include compounds having an ester of a long-chain alkylcarboxylic acid.
The content of the wax agent is preferably 0.1% by mass to 10% by mass, and more preferably 0.5% by mass to 5% by mass, based on the total mass of the image recording layer.

[Formation of image recording layer]
The image recording layer is, for example, on the support, a specific binder polymer, a specific acidic compound, and an infrared absorber, other components used as necessary, and a solvent, and a coating solution prepared, It can be formed by applying a coating solution and, if necessary, drying.
From the viewpoint of solubility of the specific binder polymer, it is preferable that the solvent used for preparing the coating liquid contains an acid compound such as acetic acid.
The drying method is not particularly limited, and examples thereof include natural drying, air drying, and drying by heating.

[Positive lithographic printing plate precursor having an image recording layer having a two-layer structure]
The positive lithographic printing plate precursor according to the present disclosure has an image recording layer having a lower layer and an upper layer in this order on the support, and at least one of the lower layer and the upper layer is a specific binder polymer, a specific acidic compound, and It is preferably a layer containing an infrared absorber.
The layer containing the specific binder polymer, the specific acidic compound, and the infrared absorbing agent may be either a lower layer or an upper layer of the image recording layer, or may be both layers, but is superior in the effect of the ablation suppressing property. From the above, it is preferable that it is an upper layer of the image recording layer.
In the present disclosure, a positive type lithographic printing plate precursor having a lower layer and an upper layer is also referred to as a “two-layer structure lithographic printing plate precursor”.
The lower layer and the upper layer are preferably formed by separating the two layers.
As a method of forming the two layers separately, for example, a method of utilizing a difference in solvent solubility between a component contained in the lower layer and a component contained in the upper layer, or a method of applying a solvent rapidly after applying the upper layer And the like. It is preferable to use the latter method in combination, because the separation between layers will be more favorably performed.
Hereinafter, these methods will be described in detail, but the method of separating and applying the two layers is not limited thereto.

As a method of utilizing the difference in solvent solubility between the components contained in the lower layer and the components contained in the upper layer, when applying the coating liquid for the upper layer, a solvent system in which none of the components contained in the lower layer is insoluble is used. It is a thing. As a result, even if two-layer coating is performed, each layer can be clearly separated to form a coating film. For example, as the lower layer component, a component that is insoluble in a solvent such as methyl ethyl ketone or 1-methoxy-2-propanol that dissolves the specific binder polymer that is the upper layer component is selected, and the lower layer is applied using a solvent system that dissolves the lower layer component. After drying, the upper layer containing the specific binder polymer is dissolved with methyl ethyl ketone, 1-methoxy-2-propanol or the like, coated and dried to form a double layer.

Next, as a method of drying the solvent extremely quickly after applying the second layer (upper layer), high-pressure air is blown from a slit nozzle installed substantially at right angles to the running direction of the web, or a heating medium such as steam. Can be achieved by applying heat energy as conduction heat from the lower surface of the web from a roll (heating roll) supplied inside, or by combining them.

Coating amount after drying of a lower layer component applied onto the support of the lithographic printing plate precursor according to the present disclosure ^is preferably in the range of ^{0.5g / m 2 ~4.0g / m 2} , 0.6g /M ^{2 to} 2.5 g/m ² is more preferable. When it is 0.5 g/m ² or more, printing durability is excellent, and when it is 4.0 g/m ² or less, image reproducibility and sensitivity are excellent.
The coating amount after drying of the upper layer component ^is preferably in the range of ^{0.05g / m 2 ~1.0g / m 2} , in the range of 0.08g / ^{m 2} ~0.7g / m 2 Is more preferable. If it is 0.05 g / ^{m 2} or more, development latitude, and excellent scratch resistance, if it is 1.0 g / ^{m 2} or less, excellent sensitivity.
The lower layer and the coating amount after drying of the combined upper layer is ^preferably in the range of ^{0.6g / m 2 ~4.0g / m 2} , the range of 0.7g / ^{m 2} ~2.5g / m 2 Is more preferable. When it is 0.6 g/m ² or more, printing durability is excellent, and when it is 4.0 g/m ² or less, image reproducibility and sensitivity are excellent.

〔Underlayer〕
The lower layer of the lithographic printing plate precursor having a two-layer structure in the present disclosure may be a layer containing the specific binder polymer, the specific acidic compound, and the infrared absorber, but does not contain the specific binder polymer and the specific acidic compound. It is preferably a layer.
The lower layer of the lithographic printing plate precursor having a two-layer structure in the present disclosure is preferably an infrared-sensitive positive recording layer whose solubility in an aqueous alkali solution is improved by heat.
There is no particular limitation on the mechanism by which the heat in the lower layer improves the solubility in the alkaline aqueous solution, and any mechanism can be used as long as it contains a binder resin and improves the solubility in the heated region. The heat used for image formation includes heat generated when the lower layer containing the infrared absorber is exposed.
The lower layer whose solubility in an aqueous alkali solution is improved by heat includes, for example, novolac, a layer containing an alkali-soluble resin having hydrogen bonding ability such as urethane, a water-insoluble and alkali-soluble resin and a compound having a dissolution inhibiting action. Layers and the like are preferred.

Further, by adding an infrared absorber to the lower layer, the heat generated in the lower layer can be utilized for image formation. The structure of the lower layer containing an infrared absorbing agent, for example, a layer containing an infrared absorbing agent and a water-insoluble and an alkali-soluble resin and a compound having a dissolution suppressing action, an infrared absorbing agent, a water-insoluble and an alkali-soluble resin and an acid generator. A layer containing is preferable.

-Water-insoluble and alkali-soluble resin-
The lower layer in the present disclosure preferably contains a water-insoluble and alkali-soluble resin. By containing the water-insoluble and alkali-soluble resin, an interaction is formed between the infrared absorber and the polar group of the water-insoluble and alkali-soluble resin, and a positive photosensitive layer is formed.
The general water-insoluble and alkali-soluble resin will be described in detail below, and among them, for example, a polyamide resin, an epoxy resin, a polyacetal resin, an acrylic resin, a methacrylic resin, a polystyrene resin, a novolac type phenolic resin, etc. are preferred. be able to.
The water-insoluble and alkali-soluble resin that can be used in the present disclosure is not particularly limited as long as it has a property of dissolving when contacted with an alkaline developer, but the main chain and/or side chain in the polymer is acidic. It is preferably a homopolymer containing a group, a copolymer thereof, or a mixture thereof.
The water-insoluble and alkali-soluble resin having such an acidic group preferably has a functional group such as a phenolic hydroxyl group, a carboxy group, a sulfonic acid group, a phosphoric acid group, a sulfonamide group and an active imide group. Therefore, such a resin can be suitably produced by copolymerizing a monomer mixture containing at least one ethylenically unsaturated monomer having the above functional group. As the ethylenically unsaturated monomer having a functional group, a compound represented by the following formula and a mixture thereof can be preferably exemplified in addition to acrylic acid and methacrylic acid. In the formula below, R ⁴⁰ represents a hydrogen atom or a methyl group.

The water-insoluble and alkali-soluble resin that can be used in the present disclosure is preferably a polymer compound obtained by copolymerizing another polymerizable monomer in addition to the above polymerizable monomer. The copolymerization ratio in this case is 10 mol of a monomer that imparts alkali solubility, such as a monomer having a functional group such as a phenolic hydroxyl group, a carboxy group, a sulfonic acid group, a phosphoric acid group, a sulfonamide group, and an active imide group. % Or more, and more preferably 20 mol% or more. When the copolymerization component of the monomer imparting alkali solubility is 10 mol% or more, sufficient alkali solubility is obtained and the developability is excellent.

Examples of other polymerizable monomers that can be used include the compounds listed below.
Alkyl acrylates or alkyl methacrylates such as methyl acrylate, ethyl acrylate, propyl acrylate, benzyl acrylate, methyl methacrylate, ethyl methacrylate, cyclohexyl methacrylate and benzyl methacrylate. Acrylic acid esters and methacrylic acid esters having an aliphatic hydroxyl group such as 2-hydroxyethyl acrylate or 2-hydroxyethyl methacrylate. Acrylamide or methacrylamide such as acrylamide, methacrylamide, N-methyl acrylamide, N-ethyl acrylamide, N-phenyl acrylamide. Vinyl esters such as vinyl acetate, vinyl chloroacetate, vinyl butyrate and vinyl benzoate. Styrenes such as styrene, α-methylstyrene, methylstyrene and chloromethylstyrene. Other nitrogen atom-containing monomers such as N-vinylpyrrolidone, N-vinylpyridine, acrylonitrile and methacrylonitrile. N-methylmaleimide, N-ethylmaleimide, N-propylmaleimide, N-butylmaleimide, N-phenylmaleimide, N-2-methylphenylmaleimide, N-2,6-diethylphenylmaleimide, N-2-chlorophenylmaleimide, Maleimides such as N-cyclohexylmaleimide, N-laurylmaleimide and N-hydroxyphenylmaleimide.
Among these other ethylenically unsaturated monomers, (meth)acrylic acid esters, (meth)acrylamides, maleimides, and (meth)acrylonitrile are preferably used.

Further, as the alkali-soluble resin, the novolac resin mentioned as the other binder polymer mentioned as an optional component of the image recording layer according to the present disclosure is also preferably exemplified.
It is also possible to use the above water-insoluble and alkali-soluble resin in the image recording layer in the present disclosure.

Further, in the lower layer in the present disclosure, another resin can be used in combination as long as the effects according to the present disclosure are not impaired. Since the lower layer itself needs to exhibit alkali solubility, especially in the non-image area, it is necessary to select a resin that does not impair this property. From this point of view, examples of resins that can be used in combination include water-insoluble and alkali-soluble resins. The general water-insoluble and alkali-soluble resin will be described in detail below, and among them, for example, a polyamide resin, an epoxy resin, a polyacetal resin, an acrylic resin, a methacrylic resin, a polystyrene resin, a novolac type phenolic resin, etc. are preferred. be able to.
Further, the amount to be mixed is preferably 50% by mass or less with respect to the water-insoluble and alkali-soluble resin.

The water-insoluble and alkali-soluble resin preferably has a weight average molecular weight of 2,000 or more and a number average molecular weight of 500 or more, a weight average molecular weight of 5,000 to 300,000, and a number average molecular weight of 800 to More preferably, it is 250,000. The degree of dispersion (weight average molecular weight/number average molecular weight) of the alkali-soluble resin is preferably 1.1 to 10.
The alkali-soluble resin in the lower layer according to the present disclosure may be used alone or in combination of two or more.
The content of the alkali-soluble resin in the total solid content of the lower layer in the present disclosure is preferably 2.0% by mass to 99.5% by mass, and 10.0% by mass to 99.% by mass with respect to the total mass of the lower layer. It is more preferably 0% by mass, further preferably 20.0% by mass to 90.0% by mass. When the addition amount of the alkali-soluble resin is 2.0% by mass or more, the durability of the image recording layer (photosensitive layer) is excellent, and when it is 99.5% by mass or less, both the sensitivity and the durability are improved. Excel.

-Infrared absorber-
The lower layer may contain an infrared absorber.
The infrared absorbent is not particularly limited as long as it is a dye that absorbs infrared light and generates heat, and the infrared absorbent used in the image recording layer in the present disclosure described above can be similarly used.
A particularly preferred dye is a cyanine dye represented by the above formula (a).

The exposure sensitivity is improved by containing the infrared absorber in the lower layer.
The addition amount of the infrared absorber in the lower layer is preferably 0.01% by mass to 50% by mass, more preferably 0.1% by mass to 30% by mass, based on the total mass of the lower layer. It is particularly preferable that the content is 0.0% by mass to 10% by mass. When the addition amount is 0.01% by mass or more, the sensitivity is improved, and when it is 50% by mass or less, the uniformity of the layer is good and the durability of the layer is excellent.

-Other ingredients-
In addition, the lower layer in the lithographic printing plate precursor having a two-layer structure may contain an acid generator, an acid multiplying agent, a development accelerator, a surfactant, a printing-out agent/colorant, a plasticizer, a wax agent and the like.
As these components, the above-mentioned respective components used in the image recording layer in the present disclosure can be similarly used, and the preferred embodiments are also the same.

[Upper layer]
In the positive lithographic printing plate precursor according to the present disclosure, the upper layer in the image recording layer having a two-layer structure has a specific binder polymer, a specific acidic compound, and an infrared absorber from the viewpoint of ablation suppression property and printing durability. It is preferable to include
By using the image recording layer in the present disclosure as the upper layer, it is possible to obtain a lithographic printing plate precursor having excellent ablation suppression properties.

When the image recording layer in the present disclosure is used as the lower layer, the upper layer is also preferably the image recording layer in the present disclosure, but the upper layer may be formed as a layer other than the image recording layer in the present disclosure. In that case, the preferred embodiment of the upper layer is the same as the preferred embodiment of the lower layer described above.

<Support>
The positive planographic printing plate precursor according to the present disclosure has a support.
The support in the present disclosure is not particularly limited as long as it is a dimensionally stable plate-like material having necessary strength and durability, and examples thereof include paper and plastic (for example, polyethylene, polypropylene, polystyrene, etc.). Laminated paper, metal plate (eg, aluminum, zinc, copper, etc.), plastic film (eg, cellulose diacetate, cellulose triacetate, cellulose propionate, cellulose butyrate, cellulose acetate butyrate, cellulose nitrate, polyethylene terephthalate, polyethylene, (Polystyrene, polypropylene, polycarbonate, polyvinyl acetal, etc.), paper laminated or vapor-deposited with the above metals, or a plastic film.

As the support in the present disclosure, a polyester film or an aluminum plate is preferable, and among them, an aluminum plate which has good dimensional stability and is relatively inexpensive is particularly preferable. A suitable aluminum plate is a pure aluminum plate or an alloy plate containing aluminum as a main component and containing a trace amount of a foreign element, and may be a plastic film on which aluminum is laminated or vapor-deposited. The foreign elements contained in the aluminum alloy include silicon, iron, manganese, copper, magnesium, chromium, zinc, bismuth, nickel and titanium. The content of the foreign element in the alloy is preferably 10 mass% or less.

Aluminum which is particularly suitable in the present disclosure is pure aluminum, but completely pure aluminum is difficult to produce due to refining technology, and thus may contain slightly different elements.
As described above, the composition of the aluminum plate applied to the present disclosure is not specified, and an aluminum plate that is a conventionally known and publicly known material can be appropriately used. The thickness of the aluminum plate used in the present disclosure is preferably 0.1 mm to 0.6 mm, more preferably 0.15 mm to 0.4 mm, and particularly preferably 0.2 mm to 0.3 mm. preferable.

Such aluminum plate may be subjected to surface treatment such as surface roughening treatment and anodizing treatment, if necessary. Regarding the surface treatment of the aluminum support, for example, a degreasing treatment with a surfactant, an organic solvent, an alkaline aqueous solution, or the like as described in detail in paragraphs 0167 to 0169 of JP 2009-175195 A, a rough surface Chemical treatment, anodization treatment, etc. are appropriately performed.
The aluminum surface that has been subjected to the anodizing treatment is optionally subjected to a hydrophilic treatment.
As the hydrophilic treatment, a method of treating with an alkali metal silicate (for example, sodium silicate aqueous solution) method, potassium fluorozirconate or polyvinylphosphonic acid, as disclosed in paragraph 0169 of JP2009-175195A. Are used.
The support described in JP 2011-245844 A is also preferably used.

<Undercoat layer>
The positive lithographic printing plate precursor according to the present disclosure may have an undercoat layer between the support and the image recording layer (or the lower layer in the image recording layer), if necessary.
As the undercoat layer component, various organic compounds are used, for example, carboxymethyl cellulose, phosphonic acids having an amino group such as dextrin, organic phosphonic acid, organic phosphoric acid, organic phosphinic acid, amino acids, and a hydroxy group. Preferable examples are the amine hydrochlorides and the like. These undercoat layer components may be used alone or in combination of two or more. Details of the compound used for the undercoat layer and the method for forming the undercoat layer are described in paragraphs 0171 to 0172 of JP2009-175195A, and these descriptions are also applied to the present disclosure.
The coverage of the undercoat layer ^is preferably from ^{2mg / m 2 ~200mg / m 2} , and more preferably ^{5mg / m 2 ~100mg / m 2} . When the coating amount is within the above range, sufficient printing durability can be obtained.

<Backcoat layer>
A backcoat layer is provided on the back surface of the support of the lithographic printing plate precursor according to the present disclosure, if necessary. The back coat layer is composed of a metal oxide obtained by hydrolyzing and polycondensing an organic polymer compound described in JP-A-5-45885 and an organic or inorganic metal compound described in JP-A-6-35174. A coating layer is preferably used. Among these coating layers, silicon alkoxy compounds such as Si(OCH ₃ ) ₄ , Si(OC ₂ H ₅ ) ₄ , Si(OC ₃ H ₇ ) ₄ and Si(OC ₄ H ₉ ) ₄ are available at low cost. It is particularly preferable that the coating layer of the metal oxide obtained therefrom is excellent in the developer resistance.

<<How to make a planographic printing plate>>
The method for producing the lithographic printing plate according to the present disclosure is not particularly limited as long as it is the method using the positive lithographic printing plate precursor according to the present disclosure, but the exposure for imagewise exposing the positive lithographic printing plate precursor according to the present disclosure It is preferable to include a step and a developing step of developing the exposed positive lithographic printing plate precursor using a developer having a pH of 10.0 or less in this order.
Hereinafter, each step of the manufacturing method according to the present disclosure will be described in detail.

<Exposure process>
The method for producing a lithographic printing plate according to the present disclosure includes an exposure step of imagewise exposing the positive lithographic printing plate precursor according to the present disclosure.
As a light source of actinic rays used for image exposure of the lithographic printing plate precursor according to the present disclosure, a light source having an emission wavelength in the near infrared to infrared region is preferable, and a solid laser and a semiconductor laser are more preferable. Among them, in the present disclosure, it is particularly preferable to perform image exposure with a solid laser or a semiconductor laser that emits infrared rays having a wavelength of 750 nm to 1,400 nm.
The laser output is preferably 100 mW or more, and it is preferable to use a multi-beam laser device in order to shorten the exposure time. The exposure time per pixel is preferably within 20 μsec.
Energy irradiated on the planographic printing plate precursor ^is preferably ^{10mJ / cm 2 ~300mJ / cm 2} . Within the above range, the solubility of the image recording layer in an alkaline aqueous solution can be sufficiently improved, laser ablation can be suppressed, and image damage can be prevented.

The exposure in the present disclosure can be performed by overlapping the light beams of the light source. The overlap means that the sub-scanning pitch width is smaller than the beam diameter. The overlap can be quantitatively expressed by FWHM/sub-scanning pitch width (overlap coefficient) when the beam diameter is represented by the beam intensity half width (FWHM). In the present disclosure, this overlap coefficient is preferably 0.1 or more.

The scanning method of the light source of the exposure apparatus that can be used in the present disclosure is not particularly limited, and a cylinder outer surface scanning method, a cylinder inner surface scanning method, a flat surface scanning method, or the like can be used. Further, the channel of the light source may be a single channel or a multi-channel, but the multi-channel is preferably used in the case of the cylindrical outer surface type.

<Developing process>
The method of preparing a lithographic printing plate according to the present disclosure includes a developing step of developing the exposed positive lithographic printing plate precursor with a developer having a pH of 10.0 or less.
The developer used in the developing step is not particularly limited as long as it has a pH of 10.0 or less.
The developer is preferably an aqueous solution.
In addition, in the method for producing a lithographic printing plate according to the present disclosure, development may be performed using a developer having a pH of more than 10.0. For example, development can be performed using a known developing solution such as the developing solutions described in paragraphs 0270 to 0292 of JP2003-1956A.

Further, in order to improve the developability, the developer may contain a surfactant.
The surfactant used in the developer may be any of anionic, nonionic, cationic, and amphoteric surfactants, but as described above, anionic and nonionic surfactants. Agents are preferred.
As the anionic, nonionic, cationic, and amphoteric surfactants used in the developing solution in the present disclosure, those described in paragraphs 0128 to 0131 of JP2013-134341A can be used.

In addition, the HLB value is preferably 6 or more, and more preferably 8 or more from the viewpoint of stable solubility in water or turbidity.
The surfactant used in the developer is preferably an anionic surfactant and a nonionic surfactant, and an anionic surfactant containing a sulfonic acid or a sulfonate and a nonionic compound having an aromatic ring and an ethylene oxide chain. Surfactants are especially preferred.
The surfactants can be used alone or in combination.
The content of the surfactant in the developer is preferably 0.01% by mass to 10% by mass, more preferably 0.01% by mass to 5% by mass.

The developing solution used in the developing step is not particularly limited as long as it is a developing solution having a pH of 10.0 or less, but is preferably a developing solution having a pH of 8.0 to pH 10.0, and a developing solution having a pH of 9.0 to pH 9.9. It is more preferably a liquid.
In such a relatively low pH developer, compared with a conventionally used high pH developer having a pH of about 12, for example, a decrease in pH due to dissolution of CO _{2 in} the atmosphere is suppressed. Easy to be affected. That is, it can be said that the low pH provides excellent stability during use or storage of the developer.
In the low pH developer, the decrease in the pH of the developer is suppressed as described above, so that the decrease in the developability and the generation of development residue are suppressed.
Further, in order to keep the pH of the low pH developer at the initial value, it is also preferable to use the developer as a buffer solution. As the buffer solution, a carbonate buffer system is particularly preferable.
In the present disclosure, the carbonate buffer system refers to a buffer solution containing carbonate ion and hydrogen carbonate ion as a buffering agent.
In order to make the carbonate ion and the hydrogen carbonate ion exist in the developing solution, a carbonate and a hydrogen carbonate may be added to the developing solution, or the carbonate may be added by adding the carbonate or the hydrogen carbonate to adjust the pH. Ions and hydrogen carbonate ions may be generated. The carbonate and hydrogen carbonate are not particularly limited, but are preferably alkali metal salts. Examples of the alkali metal include lithium, sodium and potassium, with sodium being particularly preferred. These may be used alone or in combination of two or more.

The total amount of carbonate and hydrogen carbonate is preferably 0.3% by mass to 20% by mass, more preferably 0.5% by mass to 10% by mass, and further preferably 1% by mass to 5% by mass with respect to the total mass of the developer. % Is particularly preferred. When the total amount is 0.3% by mass or more, the developability and processing ability are not deteriorated, and when the total amount is 20% by mass or less, it is difficult to form a precipitate or a crystal. It does not easily gel and does not interfere with waste liquid treatment.

Further, for the purpose of finely adjusting the alkali concentration and assisting the dissolution of the image recording layer in the non-image area, other alkaline agents, for example, organic alkaline agents may be supplementarily used. As the organic alkaline agent, monomethylamine, dimethylamine, trimethylamine, monoethylamine, diethylamine, triethylamine, monoisopropylamine, diisopropylamine, triisopropylamine, n-butylamine, monoethanolamine, diethanolamine, triethanolamine, monoisopropanolamine, Examples thereof include diisopropanolamine, ethyleneimine, ethylenediamine, pyridine, tetramethylammonium hydroxide and the like. These other alkaline agents may be used alone or in combination of two or more.
In addition to the above, the developer may contain a wetting agent, a preservative, a chelate compound, a defoaming agent, an organic acid, an organic solvent, an inorganic acid, an inorganic salt and the like. However, when the water-soluble polymer compound is added, the plate surface tends to become sticky, especially when the developer is fatigued.

As the wetting agent, the wetting agent described in paragraph 0141 of JP2013-134341A can be preferably used. The wetting agents may be used alone or in combination of two or more. The wetting agent is preferably used in an amount of 0.1% by mass to 5% by mass, based on the total mass of the developer.

As the preservative, the preservatives described in paragraph 0142 of JP2013-134341A can be preferably used. It is preferable to use two or more preservatives in combination so as to be effective against various molds and sterilizations. The addition amount of the preservative is an amount that exerts a stable effect on bacteria, molds, yeasts, etc., and varies depending on the types of bacteria, molds, yeasts, etc. The range of 0.01% by mass to 4% by mass is preferable.

As the chelate compound, the chelate compound described in paragraph 0143 of JP2013-134341A can be preferably used. The chelating agent is selected so that it stably exists in the developer composition and does not impair the printability. The addition amount is preferably 0.001% by mass to 1.0% by mass with respect to the total mass of the developer.

As the defoaming agent, the defoaming agent described in paragraph 0144 of JP2013-134341A can be preferably used. The content of the defoaming agent is preferably in the range of 0.001% by mass to 1.0% by mass with respect to the total mass of the developer.

As the organic acid, the defoaming agent described in paragraph 0145 of JP2013-134341A can be preferably used. The content of the organic acid is preferably 0.01% by mass to 0.5% by mass with respect to the total mass of the developer.

Examples of the organic solvent include aliphatic hydrocarbons (hexane, heptane, “Isopar E, H, G” (Esso Chemical Co., Ltd.), gasoline, or kerosene), aromatic hydrocarbons (toluene, xylene). Etc.), halogenated hydrocarbons (methylene dichloride, ethylene dichloride, trichlene, monochlorobenzene, etc.), or polar solvents.

As the polar solvent, alcohols (methanol, ethanol, propanol, isopropanol, benzyl alcohol, ethylene glycol monomethyl ether, 2-ethoxyethanol, etc.), ketones (methyl ethyl ketone, cyclohexanone, etc.), esters (ethyl acetate, methyl lactate, propylene) Glycol monomethyl ether acetate, etc.) and others (triethyl phosphate, tricresyl phosphate, N-phenylethanolamine, N-phenyldiethanolamine, etc.) and the like.

Further, when the above organic solvent is insoluble in water, it can be used after being solubilized in water by using a surfactant or the like. When the developer contains an organic solvent, the concentration of the solvent is preferably less than 40 mass% from the viewpoint of safety and flammability.

As the inorganic acid and the inorganic salt, phosphoric acid, metaphosphoric acid, ammonium phosphate monobasic, ammonium phosphate dibasic, sodium phosphate monobasic, sodium phosphate dibasic, potassium phosphate monobasic, potassium phosphate dibasic, Examples thereof include sodium tripolyphosphate, potassium pyrophosphate, sodium hexametaphosphate, sodium nitrate, potassium nitrate, ammonium nitrate, sodium sulfate, potassium sulfate, ammonium sulfate, sodium sulfite, ammonium sulfite, and sodium hydrogensulfate. The content of the inorganic salt is preferably 0.01% by mass to 0.5% by mass with respect to the total mass of the developer.

The developing temperature is not particularly limited as long as it can be developed, but it is preferably 60° C. or lower, and more preferably 15° C. to 40° C. In a developing process using an automatic developing machine, the developing solution may become fatigued depending on the amount of processing, and thus the replenishing solution or a fresh developing solution may be used to recover the processing ability. As an example of the development and the treatment after the development, a method of performing alkali development, removing the alkali in the post-water washing step, performing gum treatment in the gumming step, and drying in the drying step can be exemplified. As another example, a method of simultaneously performing pre-washing, development and gumming can be preferably exemplified by using an aqueous solution containing carbonate ion, hydrogen carbonate ion and a surfactant. Therefore, the pre-water washing step does not have to be particularly performed, and it is preferable to perform the pre-water washing, the development and the gumming in one bath only after using one solution, and then to perform the drying step. After development, it is preferable to remove excess developer using a squeeze roller or the like and then perform drying.

The developing step can be suitably carried out by an automatic processor equipped with a rubbing member. As the automatic processor, for example, the automatic processor described in JP-A-2-220061 and JP-A-60-59351, which performs a rubbing treatment while conveying the lithographic printing plate precursor after image exposure, on a cylinder The lithographic printing plate precursor after image exposure set in step 1 is subjected to a rubbing treatment while rotating a cylinder, the automatic processor described in each specification of US Pat. Nos. 5,148,746, 5,568,768, and British Patent 2,297,719, etc. Is mentioned. Among them, an automatic processor using a rotating brush roll as the rubbing member is particularly preferable.

The rotating brush roll used in the present disclosure can be appropriately selected in consideration of the scratch resistance of the image area, the rigidity of the support of the planographic printing plate precursor, and the like. As the rotary brush roll, a known roll formed by planting a brush material on a plastic or metal roll can be used. For example, the metal described in JP-A-58-159533 and JP-A-3-100554 or a metal in which a brush material is implanted in a row as described in JP-B-62-167253 or It is possible to use a brush roll in which a plastic groove member is wound around a core plastic or metal roll in a radial pattern without a gap.
As the brush material, plastic fibers (for example, polyester type such as polyethylene terephthalate and polybutylene terephthalate, polyamide type such as nylon 6.6 and nylon 6.10, polyacryl type such as polyacrylonitrile, alkyl poly(meth)acrylate) Polyolefin-based synthetic fibers such as polypropylene and polystyrene) may be used. For example, fibers having a hair diameter of 20 μm to 400 μm and a hair length of 5 mm to 30 mm can be preferably used.
The outer diameter of the rotating brush roll is preferably 30 mm to 200 mm, and the peripheral speed of the tip of the brush rubbing the plate surface is preferably 0.1 m/sec to 5 m/sec. It is preferable to use a plurality of rotating brush rolls.

The rotating brush roll may rotate in the same direction or in the opposite direction to the conveying direction of the lithographic printing plate precursor, but when two or more rotating brush rolls are used, at least one rotating brush roll is used. It is preferable that the rotating brush rolls of 1 rotate in the same direction and at least one rotating brush roll rotate in the opposite direction. This further ensures removal of the image recording layer in the non-image area. Further, it is also effective to swing the rotating brush roll in the rotation axis direction of the brush roll.

After the developing step, it is preferable to provide a drying step continuously or discontinuously. Drying is performed with hot air, infrared rays, far infrared rays, or the like.
As an automatic processor preferably used in the method for producing a lithographic printing plate according to the present disclosure, an apparatus having a developing unit and a drying unit is used, and a lithographic printing plate precursor is developed and gummed in a developing tank. And then dried in the drying section to obtain a lithographic printing plate.

Further, the printing plate after development can be heated under a very strong condition for the purpose of improving printing durability. The heating temperature is preferably in the range of 200°C to 500°C. If the temperature is low, a sufficient image strengthening effect cannot be obtained, and if it is too high, problems such as deterioration of the support and thermal decomposition of the image area may occur.
The lithographic printing plate thus obtained is set on an offset printing machine and is suitably used for printing a large number of sheets.

Hereinafter, the present disclosure will be described in detail with reference to Examples, but the present disclosure is not limited thereto. In this example, "%" and "part" mean "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 constitutional units is a molar percentage, except for those specifically specified. The weight average molecular weight (Mw) is a value measured as a polystyrene conversion value by a gel permeation chromatography (GPC) method.

<Synthesis of specific binder polymer>
P-1 to P-26, which are specific binder polymers, were synthesized by the following method.

[Synthesis of P-1]
48 parts of 1-methoxy-2-propanol and 1.58 parts of acetic acid were put into a three-necked flask, and stirred at 75° C. for 30 minutes under a nitrogen stream. Monomer mB1-1: 42 parts, MMA (methyl methacrylate): 58 parts, V-601 (trade name, Dimethyl 2,2'-azobis(2-methylpropionate), FUJIFILM Wako Pure Chemical Industries, Ltd.): 0 A mixed solution of .34 parts and methanol: 12 parts was added dropwise over 2 hours. After the dropping was completed, the reaction was further performed at 75° C. for 2 hours, and then the mixture was poured into 500 parts of well-stirred water to precipitate a solid. The precipitated solid was filtered, washed with water, and dried under reduced pressure to obtain a specific binder polymer P-1.

[Synthesis of P-2 to P-24]
The specific binder polymers P-2 to P-24 were synthesized in the same manner as the specific binder polymer P-1 except that the monomers used were appropriately changed.

[Synthesis of P-25]
In a three-necked flask, N-methyl-2-pyrrolidone: 300 g, 4-hydroxy-1-(2-hydroxyethyl)-2,2,6,6-tetramethylpiperidine: 35 g, Uniol D-1200: 17 g, and Diphenylmethane diisocyanate: 48 g was added, and the mixture was reacted at room temperature for 3 hours, and then poured into well stirred water: 5000 g to precipitate a solid. The precipitated solid was filtered, washed with water, and dried under reduced pressure to obtain a specific binder polymer P-25.

[Synthesis of P-26]
The specific binder polymer P-26 was synthesized by the same method as that of the specific binder polymer P-25, except that the monomers used were appropriately changed.

The following compounds were used as the monomers for forming each structural unit. The synthetic product was synthesized by the following method and used as a monomer for forming each structural unit.

-Monomer having a basic group-
mB1-1: pentamethylpiperidyl methacrylate (Hitachi Chemical Co., Ltd.)
mB1-2:2-(dimethylamino)ethyl methacrylate (Sigma Aldrich)
mB1-3: 2-(diethylamino)ethyl methacrylate (Sigma Aldrich)
mB1-4: 2-(diisopropylamino)ethyl methacrylate (Sigma Aldrich)
mB1-5: 4-vinyl pyridine (Tokyo Chemical Industry Co., Ltd.)
mB1-6: 2-vinyl pyridine (Tokyo Chemical Industry Co., Ltd.)
mB1-7: 2-(3-(2-pyridinyl)ureido)ethyl methacrylate (synthetic product)
mB1-8: 2-(3-(3-pyridinyl)ureido)ethyl methacrylate (synthetic product)
mB1-9: 2-(3-(4-pyridinyl)ureido)ethyl methacrylate (synthetic product)
mB1-10: Tetramethylpiperidyl methacrylate (Hitachi Chemical Co., Ltd.)
mB1-11: 11-methacrylamido-3,6,9-trioxaundecanylamine (synthetic product)
mB1-12: 2-(3-(4-(dimethylamino)phenyl)ureido)ethyl methacrylate (synthetic product)
mB1-13: 4-hydroxy-1-(2-hydroxyethyl)-2,2,6,6-tetramethylpiperidine (Tokyo Chemical Industry Co., Ltd.)
mB1-14: 3-(dimethylamino)-1,2-propanediol (Tokyo Chemical Industry Co., Ltd.)

(Synthesis of Monomer mB1-7)
Karens MOI (trade name; Showa Denko KK) 10.0 g was placed in a three-necked flask and stirred at room temperature. 2-Aminopyridine (Tokyo Kasei Kogyo Co., Ltd., 5 g) was slowly added dropwise thereto. After reacting for 1 hour at room temperature, it was diluted with 100 g of hexane and the precipitated solid was collected by filtration. It was washed with and the monomer mB1-7 was obtained.

(Synthesis of Monomers mB1-8, mB1-9, and mB1-12)
In the synthesis of the monomer mB1-7, 2-aminopyridine is replaced with the corresponding amine (3-aminopyridine, 4-aminopyridine, or N,N-dimethyl-1,4-phenylenediamine; either (Tokyo Kasei Kogyo ( (Strain)), except that the monomer mB1-7 was synthesized in the same manner.

(Synthesis of Monomer mB1-11)
100 g of ethyl acetate, 100 g of water, 10 g of 1,11-diamino-3,6,9-trioxaundecane, and 5 g of benzoic acid were placed in a three-necked flask and stirred at room temperature. Methacrylic acid anhydride was put therein and reacted at room temperature for 3 hours. After adjusting the pH of Hanno station to 10 or more with a 1 M aqueous sodium hydroxide solution, the oil phase was extracted with ethyl acetate. The solvent of the obtained oil phase solution was distilled off at 40° C. under reduced pressure of 120 mmHg to obtain a monomer mB1-11.

-Other monomers-
MMA: Methyl methacrylate (Tokyo Chemical Industry Co., Ltd.)
EHMA: Ethylhexyl methacrylate (Tokyo Chemical Industry Co., Ltd.)
BnMA: benzyl methacrylate (Tokyo Chemical Industry Co., Ltd.)
MAm: Methacrylamide (Tokyo Chemical Industry Co., Ltd.)
MDI: Diphenylmethane diisocyanate (Japan Polyurethane Industry Co., Ltd.)
PPG1200: Polypropylene glycol, Uniol D-1200 (NOF Corporation)

In addition, in Tables 1 to 4, the structural units derived from the above monomers are shown in the column of the specific binder polymer.
The structural units B1-1 to B1-14 shown in Tables 1 to 4 are structural units derived from the above-mentioned monomer having a basic group, and are the same as those in the specific examples B1-1 to B1-14 described above. Applicable
Further, the structural units (MMA), (EHMA), (BnMA), (MAm), (MDI), and (PPG1200) described in Tables 1 to 4 are structural units derived from the above-mentioned other monomers. , Has the structure shown below.

Further, the details of the specific acidic compound and comparative compound used in Examples and Comparative Examples are shown below. The specific acidic compounds A1 to A9 correspond to the specific examples A1 to A9 described above, respectively.
A1: Sebacic acid (Tokyo Chemical Industry Co., Ltd.)
A2: Terephthalic acid (Tokyo Chemical Industry Co., Ltd.)
A3: trimellitic acid (Tokyo Chemical Industry Co., Ltd.)
A4: adipic acid (Tokyo Chemical Industry Co., Ltd.)
A5: Malonic acid (Tokyo Chemical Industry Co., Ltd.)
A6: Citric acid (Tokyo Chemical Industry Co., Ltd.)
A7: Ethylenediaminetetraacetic acid (Tokyo Chemical Industry Co., Ltd.)
A8: Triethylenetetramine hexaacetic acid (Cillest Co., Ltd.)
A9: Hyaluronic acid tetrasaccharide (Tokyo Chemical Industry Co., Ltd.)
C1: Benzoic acid (Tokyo Chemical Industry Co., Ltd.)
C2: 2-ethylhexanoic acid (Tokyo Chemical Industry Co., Ltd.)
C3: 4-Dimethylaminobenzoic acid (Tokyo Chemical Industry Co., Ltd.)

The chemical structural formulas of the comparative compounds C1 to C3 are shown below.

(Examples 1-1 to 1-41 and Comparative examples 1-1 to 1-4)
<Preparation of support>
A support was prepared in the same manner as in paragraphs 0224 to 0297 of WO 2015/152209. This support was used in all examples and comparative examples.

<Formation of undercoat layer>
After coating the undercoat layer coating liquid 1 shown below on the support, it was dried at 80° C. for 15 seconds to form an undercoat layer. The coating amount after drying was 15 mg/m ² .

[Undercoat layer coating liquid 1]
-The following copolymer having a weight average molecular weight of 28,000: 0.3 part-Methanol: 100 parts-Water: 1 part

In the above chemical formula, the subscripts in parentheses represent the content (mass %) of each structural unit. Et represents an ethyl group.

<Preparation of photosensitive resin composition>
Photosensitive resin composition (I) was prepared by mixing the components described in the composition below. The photosensitive resin composition (I) is a positive type photosensitive resin composition.

[Photosensitive resin composition (I)]
-Specific binder polymer described in Tables 1 to 3: added amount described in Tables 1 to 3-specific acidic compound or comparative compound described in Tables 1 to 3: added amount described in Tables 1 to 3 Infrared absorbers shown in Tables 1 to 3 (IR-1 to IR-3 below): 0.045 parts Megafac (registered trademark) F-780 (fluorine-based surfactant, DIC Corporation): 0 0.03 parts Acetic acid: 12.0 parts Methyl ethyl ketone: 13.0 parts 1-Methoxy-2-propanol: 30.0 parts 1-(4-Methylbenzyl)-1-phenylpiperidinium 5-benzoyl -4-Hydroxy-2-methoxybenzenesulfonate: 0.01 part

<Formation of image recording layer>
In each Example or Comparative Example, the above-mentioned support with an undercoat layer was coated with the above-mentioned photosensitive resin composition (I) using a wire bar and then dried in a drying oven at 150° C. for 40 seconds to obtain a specific binder. The coating amount of the polymer was set to 1.0 g/m ² , an image recording layer was provided, and a lithographic printing plate precursor was obtained.

The following evaluation was performed using the obtained planographic printing plate precursor. The evaluation results are shown in Tables 1 and 2.

<Developability>
The obtained lithographic printing plate precursor was imagewise drawn with a Trendsetter VX manufactured by Creo at a beam intensity of 9 W and a drum rotation speed of 150 rpm (revolutions per minute). Then, it was dipped in a developing bath charged with the developing solution 1 having the following composition, and the time required for developing the non-image area was measured at a developing temperature of 30°C. The immersion time at which the image density of the image recording layer measured with a Macbeth densitometer became equivalent to the image density of the support was defined as the non-image area development time, and the measured values are shown in the table. When the image density of the image recording layer did not become equal to the image density of the support 30 seconds after the immersion, it was described as "undevelopable". The shorter the non-image area development time, the better the developability.

[Developer 1]
-Water: 8,964 parts by mass-Sodium carbonate: 200 parts by mass-Sodium hydrogen carbonate: 100 parts by mass-Newcol B4SN (trade name, polyoxyethylene naphthyl ether sulfate, Nippon Emulsifier Co., Ltd.): 300 parts by mass- Ethylenediaminetetraacetate tetrasodium salt: 80 parts by mass

<Retention of image area>
The obtained lithographic printing plate precursor was immersed in a developing bath containing the developer 1 without being exposed to light, and the image density of the image recording layer measured by a Macbeth densitometer at a developing temperature of 30° C. was the image before immersion. The immersion time at which the image density of the recording layer was lowered by 3% was defined as the image part holding time. The longer the image area development time, the better the image area retention.

<Printing durability>
The obtained lithographic printing plate precursor was image-wise drawn with a Trendsetter manufactured by Creo at a beam intensity of 9 W and a drum rotation speed of 150 rpm.
Then, using PS Processor LP940H of Fuji Film Co., Ltd. charged with the developing solution 1, the developing temperature was 30° C., and the developing time was the non-image area developing time+2 seconds. The developed lithographic printing plate was continuously printed using a printing machine Lithrone manufactured by Komori Corporation. As the ink, as a model of a low-grade material, a special black ink containing calcium carbonate, manufactured by Toyo Ink Co., Ltd., was used. At this time, the printing durability was evaluated by visually measuring how many sheets can be printed while maintaining a sufficient ink density. The number of sheets in Comparative Example 1-2 was set to 100, and relative evaluation was performed by the number of sheets.

<Ablation suppression>
A transparent polyethylene terephthalate film (Fuji Film Co., Ltd.) having a thickness of 0.1 mm was brought into close contact with the surface of the lithographic printing plate precursor, and the entire surface was exposed under the same conditions as in the evaluation of the developability.
After the exposure, the polyethylene terephthalate film was removed and visually inspected to observe the degree of dirt on the surface. The case where no stain was observed was A, the case where a little stain was observed was B, and the case where it was stained to the extent that it could not be seen through the film through the film was C.
It can be said that the less the dirt is, the more excellent the abrasion resistance is. Therefore, the evaluation is preferably A or B, and more preferably A.

In Tables 1 to 3, pKaH, ClogP, base value, and Mw (weight average molecular weight) of the structural unit having a base group in the specific binder polymer, pKa, ClogP, and acid value of the acid group of the specific acidic compound, and , wherein the column of N B _/ N _a indicates the measured or calculated values by the respective aforementioned processes.
Note that N _B /N _A is the ratio of the number N _B of basic groups contained in the specific binder polymer to the number N _{A of} basic groups contained in the specific acidic compound.
These contents are the same in Table 4 described later.

(Examples 2-1 to 2-3 and Comparative examples 2-1 to 2-4)
<Preparation of a lithographic printing plate having a two-layer structure>
In each Example or Comparative Example, the following lower layer forming composition (II) was applied on the same support as in Example 1-1 by a wire bar and then dried in a drying oven at 133° C. for 60 seconds. The coating amount of the binder polymer is adjusted to 0.7 g/m ² and the lower layer is provided, and then the photosensitive resin composition (I) (specific binder polymer and specific acidity) prepared in the same manner as in Example 1-1 above. The details of the compound are shown in Table 3 below) were coated with a wire bar to form an upper layer. After coating, drying was performed at 130° C. for 50 seconds to obtain a lithographic printing plate precursor having a total coating amount of 1.0 g/m ^{2 of} the lower layer and the upper layer.

[Coating liquid composition for forming lower layer (II)]
Polymer UP-1 (compound of the following structural formula, weight average molecular weight 40,000): 3.5 parts Megafac (registered trademark) F-780: 0.07 part methyl ethyl ketone: 30.0 parts 1-methoxy -2-Propanol: 15.0 parts, γ-butyrolactone: 15.0 parts, 4,4'-bishydroxyphenyl sulfone: 0.3 parts, tetrahydrophthalic acid: 0.4 parts, p-toluenesulfonic acid: 0 0.02 part 3-methoxy-4-diazodiphenylamine hexafluorophosphate: 0.06 part-Ethyl violet counter ion changed to 6-hydroxynaphthalene sulfonic acid: 0.15 part

In the above structure, the subscripts in parentheses represent the content (mol %) of each structural unit.

Using the obtained lithographic printing plate precursor having a two-layer structure, the developability, the image area retaining property, the printing durability and the ablation suppressing property were evaluated by the same method as described above, and the evaluation results are shown in Table 4. Described in.

From the results shown in Tables 1 to 4, the positive planographic printing plate precursors in Examples 1-1 to 1-41 and 2-1 to 2-3, which are positive planographic printing plate precursors according to the present disclosure, were compared. It can be seen that the abrasion resistance is superior to the positive planographic printing plate precursors of Examples 1-1 to 1-4 and 2-1 to 2-4.
Further, it can be seen that the positive type lithographic printing plate precursors in Examples 1-1 to 1-41 and 2-1 to 2-3 are also excellent in developability, image area retention and printing durability.

Claims (11)

A support, and an image recording layer formed on the support,
The image recording layer is
A binder polymer having a structural unit having a basic group,
An acidic compound having two or more acid groups and having a molecular weight of 10,000 or less;
A positive planographic printing plate precursor containing an infrared absorber. The positive planographic printing plate according to claim 1, wherein the binder polymer has a constitutional unit represented by the following formula (1), the following formula (2), or the following formula (3) as the constitutional unit having the base group. Original printing plate.

In formulas (1) to (3), R ¹ represents a hydrogen atom or a methyl group, X ¹ represents a single bond, an ester bond or an amide bond, and L ^{1 to} L ⁴ each independently represent a single bond or a divalent group. , Base ¹ and Base ² each independently represent a monovalent base group, Base ³ represents a divalent base group, and Y ^{1 to} Y ⁴ each independently represent -O- or -NR-. R represents a hydrogen atom or an alkyl group, and A ¹ represents a trivalent linking group. A ¹ or L ² and Base ² may combine to form a ring, or at least one of L ³ and L ⁴ and Base ³ may combine to form a ring, and L ³ and L ⁴ And may combine with each other to form a ring. The positive planographic printing plate precursor according to claim 1 or 2, wherein the base group is a group containing a nitrogen atom. The positive planographic printing according to any one of claims 1 to 3, wherein the basic group is a tertiary amino group, a group having a nitrogen-containing aliphatic ring, or a group having a nitrogen-containing aromatic ring. Original edition. The positive type lithographic printing plate precursor according to any one of claims 1 to 4, wherein the base group is a group having a nitrogen-containing aliphatic ring or a group having a nitrogen-containing aromatic ring. The positive type lithographic printing plate precursor as claimed in claim 1, wherein the base group is a group having a piperidine ring. The ratio of the number N _{B of the} basic groups of the binder polymer to the number N _{A of the} acid groups of the acidic compound is N _B /N _A =1/1.1 to 40. Item 7. The positive planographic printing plate precursor as described in any one of Item 6. The ratio of the number N _{B of the} basic groups contained in the binder polymer to the number N _{A of the} acid groups contained in the acidic compound is N _B /N _A =1/1.1 to 30. Item 9. The positive planographic printing plate precursor as described in any one of Item 7. The positive planographic printing plate precursor according to any one of claims 1 to 8, wherein the acidic compound is a polyvalent carboxylic acid compound. The positive planographic printing plate precursor according to any one of claims 1 to 9, wherein the acidic compound has a molecular weight of 100 to 1,000. An exposure step of image-exposing the positive lithographic printing plate precursor according to any one of claims 1 to 10;
A developing step of developing the exposed positive lithographic printing plate precursor using a developer having a pH of 10.0 or less, in this order,
Method of making a lithographic printing plate.