WO2011048912A1

WO2011048912A1 - Heat-sensitive lithographic printing plate and printing method thereof

Info

Publication number: WO2011048912A1
Application number: PCT/JP2010/066753
Authority: WO
Inventors: 隆宮崎; 由人大橋; 大輔土居
Original assignee: 三菱製紙株式会社
Priority date: 2009-10-23
Filing date: 2010-09-28
Publication date: 2011-04-28
Also published as: DE112010004234B4; CN102712202B; CN102712202A; DE112010004234T5

Abstract

Disclosed is a heat-sensitive lithographic printing plate which has good printing durability and background stain resistance (water retainability). Also disclosed is a heat-sensitive lithographic printing plate which is improved with respect to printing defects due to head dust and image blurring due to the sticking phenomenon, while having sufficient printing durability and background stain resistance (water retainability). Specifically disclosed is a heat-sensitive lithographic printing plate which comprises, on a water-resistant supporting body, at least two image formation layers that contains a water-soluble polymer compound and a thermoplastic resin. In the heat-sensitive lithographic printing plate, an image formation layer (B) that is farthest from the water-resistant supporting body and an image formation layer (A) that is closer to the water-resistant supporting body than the image formation layer (B) satisfy the condition (i) and/or the condition (ii) described below. (i) The ratio of the thermoplastic resin to the water-soluble polymer compound in the image formation layer (A) is higher than the ratio of the thermoplastic resin to the water-soluble polymer compound in the image formation layer (B). (ii) The ratio of at least one compound, which is selected from among the compounds represented by general formulae (1)-(4), to the water-soluble polymer compound in the image formation layer (A) is higher than the ratio of at least one compound, which is selected from among the compounds represented by general formulae (1)-(4), to the water-soluble polymer compound in the image formation layer (B).

Description

Thermosensitive planographic printing plate and printing method thereof

The present invention generally relates to a heat-sensitive lithographic printing plate using an image forming layer that undergoes phase conversion by heat, and more specifically, a heat-sensitive lithographic plate that does not require a layer removal process such as a conventional ablation method or an on-press development method. The present invention relates to a printing plate and a printing method thereof.

In recent years, various plate-making methods for lithographic printing plates using various digital printers have been proposed with the development of computers and peripheral devices. For example, JP-A-6-138719 and JP-A-6-250424 disclose plate making using a dry electrophotographic laser printer, and JP-A-9-58144 discloses on-demand using hot-melt ink. A plate making by an ink jet printer, and a plate making by a thermal printer using a thermal transfer ink ribbon are known from JP-A 63-166590.

The plate making method using a printer as described above is roughly divided from the conventional light mode type using a visible light laser or the like, and has an advantage that it is not restricted by safety light in handling. In addition, printing plates made by these plate making methods are collectively referred to as processless printing plates because they do not require post-exposure development processing that is normally used in conventional optical mode types.

However, all of the above processless printing plates are formed by forming a printing plate by transferring and imparting a grease-sensitive (that is, lithographic printing ink inking property) recorded image to the surface of a support provided with a water retention layer. Therefore, there were the following problems.

1) Since a layer for forming an image is hydrophilic, adhesion of toner, ink or the like is not sufficient. For example, the transfer toner image density is insufficient, or white spots occur in the transferred image.
2) A problem that the transfer image is not sufficiently fixed, the printing durability is lowered, and a part of a small point character or a low dot image is lost.
3) A problem that a thin background smudge occurs as a result of irregularly transferring a small amount of toner to the non-image area or rubbing the thermal transfer ink ribbon.

On the other hand, we propose a processless printing plate that provides an oleophilic image area by providing an image-forming layer containing a thermoplastic resin or a heat-meltable substance on a support and performing thermal printing with a thermal head or infrared laser. Has been.

For example, Japanese Patent Application Laid-Open No. 58-199153 (Patent Document 1) or Japanese Patent Application Laid-Open No. 59-174395 (Patent Document 2) directly draws heat on an image forming layer with a thermal head or the like without using a thermal transfer ribbon or the like. A heat-sensitive lithographic printing plate from which an oleophilic image area can be obtained is described. JP 2000-190649 A (Patent Document 3) and JP 2000-301846 A (Patent Document 4) describe a thermosensitive lithographic printing plate in which an oleophilic image portion can be obtained by heat drawing with an infrared laser or the like. Is described. In normal lithographic printing, both water and ink are simultaneously supplied to the oleophilic image area obtained as described above, the image area accepts colored ink, and the other non-image areas are hydrophilic. Therefore, printing is performed by selectively receiving water and transferring the ink received on the image onto a printing medium such as paper.

However, these heat-sensitive lithographic printing plates generally do not have a sufficient lipophilic / hydrophilic difference between the image area and the non-image area, so that it is difficult to obtain a clear printed image and the printing durability is insufficient. , Had a problem that soiling is likely to occur.

JP-A-63-64747 (Patent Document 5) proposes a method in which an image forming layer contains an inorganic pigment, a thermoplastic resin, and a heat-meltable substance as a heat-sensitive lithographic printing plate capable of obtaining a clear and high image density. Has been. The thermosensitive lithographic printing plates described in Patent Document 3 and Patent Document 4 described above are made of a heat-meltable substance that exhibits lipophilicity in order to improve the balance between the lipophilicity of the image area and the hydrophilicity of the non-image area. A method of coating with a substance having a specific thermal conductivity and a technique of hydrophobizing the hydrophilic group of a hydrophilic polymer using a chelate reaction by heat are also disclosed. However, in both cases, it is difficult to control the reaction, and the difference in lipophilicity / hydrophilicity between the image area and the non-image area is not sufficient. The remaining.

With respect to problems such as printing durability and background stains, Japanese Patent Application Laid-Open No. 11-95417 (Patent Document 6) uses a crosslinked hydrophilic resin such as polyvinyl alcohol or carboxymethyl cellulose in the image forming layer. Although it is described that the property and water retention are improved, since the phase conversion of the hydrophilic resin itself is utilized, the level of lipophilicity in the image area is low, and the difference between lipophilicity / hydrophilicity is It was not enough. JP-A-2000-75471 (Patent Document 7) uses a thermoplastic resin, a wax dispersion, a water repellent, etc. as a hydrophobic substance, and uses gelatin, polyvinyl alcohol or the like as a hydrophilic substance, and is particularly resistant to water. However, the difference in lipophilicity / hydrophilicity was not sufficient.

Japanese Patent Application Laid-Open No. 2000-238451 (Patent Document 8) has an image forming layer containing a photothermal conversion substance, thermoplastic resin particles and resin particle isolating substance on a support, and the content ratio of the photothermal conversion substance is a film. Although a technique for improving printing durability by having a gradient in the thickness direction has been introduced, it has not been fully satisfactory. Accordingly, there is a need for a heat-sensitive lithographic printing plate using an image forming layer that undergoes phase conversion by heat, which does not require layer removal processing such as an ablation method or an on-machine development method, and has good printing durability and stain resistance. It was done.

In JP-A-2006-272941 (Patent Document 9), a lithographic printing plate having an image-forming layer containing a reactant that can be converted to hydrophobicity by heat and a colorant that develops color when heated, and a hydrophilic layer on the outermost layer. In the aforementioned Patent Document 8, the support has an image forming layer containing a photothermal conversion substance, thermoplastic resin particles and resin particle isolating substance, and the content ratio of the photothermal conversion substance has a gradient in the film thickness direction. JP 2009-255498 A (Patent Document 10) discloses a technique for adding a specific compound such as diphenylalkane or the like, benzylnaphthalene, dibenzyl oxalate, or diphenoxymethylbenzene. Each lithographic printing plate is disclosed, but these also have insufficient difference in hydrophobicity / hydrophilicity, so that the printing durability is insufficient and scumming is likely to occur. A problem that remained.

Furthermore, since the direct thermal lithographic printing plates described in Patent Document 1, Patent Document 2, Patent Document 9, Patent Document 10 and the like are directly heated and drawn by a thermal head or the like, in addition to the above problems, further, The image area that is melted by heat adheres to the thermal head and the image is distorted, so-called sticking occurs. There is a problem in that printing defects due to so-called head debris are liable to occur due to the heat transfer inhibition from the thermal head and good image formation cannot be performed. Therefore, the layer removal process such as ablation method or on-machine development method that has good printing durability and stain resistance (water retention), improved printing defects due to head debris and image disturbance due to sticking phenomenon There has been a demand for a heat-sensitive lithographic printing plate using an image forming layer which does not require a phase change by heat.

JP 58-199153 A JP 59-174395 A JP 2000-190649 A JP 2000-301846 A JP-A-63-64747 JP-A-11-95417 JP 2000-75471 A JP 2000-238451 A JP 2006-229441 A JP 2009-255498 A

Accordingly, the first object of the present invention is to provide a phase change by heat that does not require a layer removal treatment such as an ablation method or an on-press development method, which has good printing durability and stain resistance (water retention). Another object of the present invention is to provide a heat-sensitive lithographic printing plate using an image forming layer. Second, to provide a heat-sensitive lithographic printing plate having good printing durability and background stain resistance (water retention), improved printing defects due to head scum, and improved image disturbance due to sticking phenomenon. It is in.

The above problems have been solved by the following means.
(1) An image forming layer (B) which has at least two image forming layers containing a water-soluble polymer compound and a thermoplastic resin on a water resistant support, and is most distant from the water resistant support, and an image forming layer A heat-sensitive lithographic printing plate that satisfies the following requirements i) and / or ii) in the image forming layer (A) closer to the water-resistant support than (B).
i) The ratio of the thermoplastic resin to the water-soluble polymer compound in the image forming layer (A) is higher than the ratio of the thermoplastic resin to the water-soluble polymer compound in the image forming layer (B).
ii) The ratio of at least one compound selected from the compounds represented by the following general formulas (1) to (4) to the water-soluble polymer compound in the image forming layer (A) is the water solubility in the image forming layer (B). Higher than the ratio of at least one compound selected from the compounds represented by the following general formulas (1) to (4) to the functional polymer compound.

In the formula, X ₁ represents —O— or —CO—O—,
R ₁ , R ₂ and R ₃ each independently represent a hydrogen atom, an alkyl group or an aryl group, or R ₁ , R ₂ and R ₃ are bonded to each other to form an aromatic ring;
R ₄ , R ₅ and R ₆ each independently represent a hydrogen atom, an alkyl group or an aryl group, or R ₄ , R ₅ and R ₆ are bonded to each other to form an aromatic ring;
n represents an integer of 1 to 10.

In the formula, R ₇ represents an alkyl group, an aryl group, an alkylcarbonyl group, an arylcarbonyl group, an alkylsulfonyl group or an arylsulfonyl group, and the naphthalene ring of the general formula (2) may further have a substituent. Good.

In the formula, R ₈ and R ₉ each independently represent a hydrogen atom, a halogen atom, an alkyl group having 1 to 4 carbon atoms or an alkoxy group having 1 to 4 carbon atoms, and X ₂ represents a single bond or —O—. N represents an integer of 1 to 4.

In the formula, R ₁₀ , R _{10 ′} , R ₁₁ and R _{11 ′} each independently represent a hydrogen atom, a halogen atom, an alkyl group, an aryl group, an alkoxy group, an alkylcarbonyl group, an arylcarbonyl group, an alkoxycarbonyl group or An aryloxy group is shown.

(2) The difference between the ratio of the thermoplastic resin to the water-soluble polymer compound in the image forming layer (A) and the ratio of the thermoplastic resin to the water-soluble polymer compound in the image forming layer (B) is 0. The heat-sensitive lithographic printing plate according to (1), which is 5 or more.
(3) The ratio of the thermoplastic resin to the water-soluble polymer compound in the image forming layer (A) is 1 to 20, and the ratio of the thermoplastic resin to the water-soluble polymer compound in the image forming layer (B) is 0. The heat-sensitive lithographic printing plate as described in (1) or (2) above, which is 1 to 3.
(4) The ratio of at least one compound selected from the compounds represented by the general formulas (1) to (4) to the water-soluble polymer compound in the image forming layer (B) is 0.5 or less. The heat-sensitive lithographic printing plate as described in (1) above.
(5) The ratio of at least one compound selected from the compounds represented by the general formulas (1) to (4) to the water-soluble polymer compound in the image forming layer (A), and the image forming layer (B) (1) or (4), wherein the difference from the ratio of at least one compound selected from the compounds represented by the general formulas (1) to (4) to the water-soluble polymer compound is 1.0 or more ) Thermal lithographic printing plate as described.
(6) The heat-sensitive lithographic printing plate according to any one of (1) to (5), which satisfies the requirements of i) and ii).
(7) Between the image forming layer (A) and the water-resistant support, there is an undercoat layer containing at least titanium dioxide, a binder resin and a crosslinking agent having an average particle size smaller than the average dry film thickness of the undercoat layer. The heat-sensitive lithographic printing plate according to any one of (1) to (6) above.
(8) The heat-sensitive lithographic printing plate as described in any one of (1) to (7) above, wherein the image forming layer (B) contains zinc oxide or barium sulfate.
(9) Any of the above (1) to (8), wherein the image forming layer contains 5 to 30% by mass of a hardener based on the solid content of the water-soluble polymer compound contained in the entire image forming layer A heat-sensitive lithographic printing plate as described in 1.
(10) A method for printing a heat-sensitive lithographic printing plate, comprising: printing on the heat-sensitive lithographic printing plate according to any one of (1) to (9) above; and printing without removing the image forming layer.

According to the present invention, first, an image forming layer that has a good printing durability and anti-stain property (water retention) and does not require layer removal processing such as an ablation method or an on-press development method, and undergoes phase conversion by heat. A heat-sensitive lithographic printing plate using can be provided. Secondly, it is possible to provide a heat-sensitive lithographic printing plate in which, in addition to sufficient printing durability and background stain resistance (water retention), printing defects due to head debris and image disturbance due to sticking phenomenon are improved.

Hereinafter, the present invention will be described in detail.

As used herein, the term “alkyl” means a saturated straight or branched chain hydrocarbon group such as methyl, ethyl, propyl, isopropyl, n-butyl, i-butyl, 2 -Butyl, t-butyl, pentyl, hexyl, decanyl and the like.
The term “alkoxy” refers to a group to which a saturated straight or branched chain hydrocarbon group as described above is attached through an oxygen atom.
The term “halogen” means chlorine, iodine, fluorine and bromine.
The term “aryl” means a monovalent cyclic aromatic hydrocarbon group consisting of one or two fused rings, wherein at least one ring is aromatic in nature, such as phenyl, benzyl, naphthyl or Biphenyl is mentioned.

The image forming layer of the heat-sensitive lithographic printing plate that satisfies the requirement i) will be described. The heat-sensitive lithographic printing plate i) has at least two image-forming layers containing a water-soluble polymer compound and a thermoplastic resin on a water-resistant support, and is more water-resistant than the image-forming layer (B). Ratio of the thermoplastic resin to the water-soluble polymer compound in the image forming layer (A) (hereinafter also simply referred to as the image forming layer (A)) close to (the mass of the thermoplastic resin / the mass of the water-soluble polymer compound) Is higher than the ratio of the thermoplastic resin to the water-soluble polymer compound in the image forming layer (B) farthest from the water-resistant support (hereinafter also simply referred to as image forming layer (B)). By providing such at least two image forming layers on a water-resistant support, layer removal treatment such as ablation method or on-press development method, which has good printing durability and scum resistance (water retention), can be performed. It is possible to provide a heat-sensitive lithographic printing plate using an image forming layer that does not require a phase conversion by heat.

In the present invention, the reason why good printing durability and soil resistance (water retention) can be obtained by the heat-sensitive lithographic printing plate satisfying the form i) is not clear, but is presumed as follows. .

The heat-sensitive lithographic printing plate (i) has an image forming layer that is converted to hydrophobicity by using phase conversion by heat on a water-resistant support. Here, the layer to be converted to hydrophobic means that when heat is applied, part of the layer is melted and converted to hydrophobic, and the portion to which heat is not applied retains the hydrophilicity of the original layer. Yes. More specifically, when heat is applied, a part of the image forming layer melts and becomes hydrophobic, so that the thermoplastic resin embedded in the water-soluble polymer compound oozes out on the surface of the layer to make it hydrophobic. Sex is expressed. On the other hand, the non-printed portion, that is, the non-image portion of the thermoplastic resin remains buried in the water-soluble polymer compound and thus does not exhibit hydrophobicity. In this way, the difference in hydrophobicity / hydrophilicity between the image area and the non-image area can be improved. It is important to maintain enough. In the present invention, by reducing the ratio of the thermoplastic resin to the water-soluble polymer compound in the image forming layer (B) farthest from the water-resistant support, the hydrophilicity of the surface is increased and the water retention during printing is improved. At the same time, the improved hydrophobicity is overcome by providing an image forming layer (A) having a higher thermoplastic resin ratio than the image forming layer (B) and close to a water-resistant support, It is estimated that the thermoplastic resin can be sufficiently exuded to the surface during image formation, and both high printing durability and ground stain resistance (water retention) can be achieved.

In the heat-sensitive lithographic printing plate of i), the ratio of the thermoplastic resin to the water-soluble polymer compound in the image-forming layer (A) is higher than that in the image-forming layer (B). There is no limitation on the method for producing the printing plate. For example, the image forming layer (A) is applied and then the image forming layer (B) is sequentially applied and stacked, or multiple layers are simultaneously formed by a slide hopper method. There is a method of applying.

The ratio of the thermoplastic resin to the water-soluble polymer compound in the image forming layer (A) may be any ratio as long as the ratio is higher than that in the image forming layer (B). The difference between the ratio in A) and the ratio in the image forming layer (B) is preferably 0.5 or more.

When three image forming layers are provided in the heat-sensitive lithographic printing plate of i), an image forming layer (C) may be provided between the image forming layer (A) and the image forming layer (B). The ratio of the thermoplastic resin to the water-soluble polymer compound in the image forming layer (C) may be higher or lower than that in the image forming layer (B), but the ratio in the image forming layer (A). It is preferable that the ratio is lower than that in the image forming layer (B).

In the heat-sensitive lithographic printing plate of i), the ratio of the thermoplastic resin to the water-soluble polymer compound in the image forming layer (B) (the mass of the thermoplastic resin / the mass of the water-soluble polymer compound) is 0.01 to 10 Preferably, it is 0.1-3. The ratio in the image forming layer (A) is preferably from 0.1 to 50, more preferably from 1 to 20.

I) The image forming layer of the heat-sensitive lithographic printing plate contains a thermoplastic resin. Such a thermoplastic resin refers to a solid organic polymer compound made of a chain polymer and exhibiting plasticity when heated. The thermoplastic resin of the present invention is added as a thermoplastic resin aqueous dispersion in a coating liquid used for forming an image forming layer, and the coating liquid is applied and dried to form a thermoplastic resin in the image forming layer. It exists as resin particles. Representative examples of thermoplastic resins include styrene butadiene copolymers, acrylonitrile butadiene copolymers, methyl methacrylate butadiene copolymers, styrene acrylonitrile butadiene copolymers, styrene methyl methacrylate butadiene copolymers and other synthetic rubber latexes and their modifications. Things. Examples of modified products of synthetic rubber latex include amino-modified products, polyether-modified products, epoxy-modified products, fatty acid-modified products, carbonyl-modified products, and carboxy-modified products. Other examples of thermoplastic resins include styrene maleic anhydride copolymer, methyl vinyl ether maleic anhydride copolymer, polyacrylic acid copolymer, polystyrene, styrene / acrylic acid ester copolymer, polyacrylic acid ester, Also included are polymethacrylic acid esters, acrylic acid ester / acrylic acid ester copolymers, and low melting point polyamide resins. These thermoplastic resins can be used alone or in combination of two or more. In view of the affinity with the printing ink vehicle (binder component), the thermoplastic resin is preferably a synthetic rubber latex, and particularly preferably a styrene-butadiene copolymer and a modified product thereof. The blending amount of the thermoplastic resin in the entire image forming layer is preferably 5 to 50% by mass with respect to the solid content of the entire image forming layer.

Further, in order to make the melting and fusing effect due to heat easy to develop, the glass transition temperature of the thermoplastic resin is preferably 50 to 150 ° C., more preferably 55 to 120 ° C. If the glass transition temperature is less than 50 ° C., a phase change occurs in a liquid state during the production process, and oleophilicity appears in the non-image area, which may cause printing stains. When the glass transition temperature exceeds 150 ° C., the polymer is hardly melted by heat, and it may be difficult to form a strong image with a relatively small output laser or a small thermal printer.

I) The image forming layer of the heat-sensitive lithographic printing plate contains a water-soluble polymer compound. Examples of such water-soluble polymer compounds include polyvinyl alcohol and modified products thereof (for example, carboxy-modified polyvinyl alcohol, acetoacetyl group-modified polyvinyl alcohol, silanol-modified polyvinyl alcohol), hydroxyethyl cellulose, methyl cellulose, carboxymethyl cellulose, pullulan and starch, and Examples thereof include polysaccharides such as derivatives, gelatin, casein, sodium alginate, polyvinylpyrrolidone, styrene / maleic acid copolymer salts, styrene / acrylic acid copolymer salts, and the like. These water-soluble polymer compounds may be used alone or in combination of two or more. In particular, gelatin and polyvinyl alcohol rich in film formation and modified products thereof are selected because they are preferable for maintaining hydrophilicity in the non-image area. The blending amount of the water-soluble polymer compound in the entire image forming layer is preferably 0.5 to 50% by mass with respect to the total solid content of the entire image forming layer.

In order to improve the water resistance and mechanical strength of the non-image area, the image forming layer preferably contains a hardening agent (waterproofing agent) depending on the type of the water-soluble polymer compound. As the hardener, those imparting water resistance by promoting crosslinking of the resin can be used. For example, melamine resin, epoxy resin, polyisocyanate compound, aldehyde compound, silane compound, chromium alum, divinyl sulfone, etc. Can be mentioned. In particular, when the water-soluble polymer compound is gelatin, divinyl sulfone is preferably used as the hardener, and when the water-soluble polymer compound is polyvinyl alcohol, glyoxal is preferably used as the hardener. The blending amount of the hardener in the entire image forming layer is preferably 0.01 to 30% by mass, more preferably 5 to 5% by weight based on the solid content of the water-soluble polymer compound contained in the entire image forming layer. 30% by mass.

The image forming layer i) can contain a heat-meltable substance, and is one of the more preferable forms from the viewpoint of printing durability. The heat-meltable substance to be contained is preferably an organic compound having a melting point of 50 to 150 ° C. If the melting point of the heat-meltable material is less than 50 ° C., it may melt during the production process and cause printed soiling. On the other hand, if the melting point of the hot-melt material exceeds 150 ° C., it may be difficult to melt by applying heat from a thermal head or the like, and the lipophilicity may be poor. Examples of the heat-meltable substance preferably used include waxes such as carnauba wax, microcrystalline wax, paraffin wax, and polyethylene wax, and fatty acids such as lauric acid, stearic acid, oleic acid, palmitic acid, behenic acid, and montanic acid. And esters or amides thereof. Further, as the heat-meltable substance, compounds represented by the general formulas (1) to (4) described in detail later in this specification may be used. Of the compounds represented by the general formulas (1) to (4), preferred compounds are 1- (1-naphthoxy) -2-phenoxyethane, 1- (2-naphthoxy) -4-phenoxybutane, 1- ( 2-Isopropylphenoxy) -2- (2-naphthoxy) ethane, 1- (4-methylphenoxy) -3- (2-naphthoxy) propane, 1- (2-methylphenoxy) -2- (2-naphthoxy) ethane 1- (3-methylphenoxy) -2- (2-naphthoxy) ethane, 1- (2-naphthoxy) -2-phenoxyethane, 1- (2-naphthoxy) -6-phenoxyhexane, 1-phenoxy-2 -(2-phenylphenoxy) ethane, 1- (2-methylphenoxy) -2- (4-phenylphenoxy) ethane, 1,4-diphenoxybutane, 1,4-bis ( -Methylphenoxy) butane, 1,2-di (3,4-dimethylphenoxy) ethane, 1-phenoxy-3- (4-phenylphenoxy) propane, 1- (4-tert-butylphenoxy) -2-phenoxyethane 1,2-diphenoxyethane, 1- (4-methylphenoxy) -2-phenoxyethane, 1- (2,3-dimethylphenoxy) -2-phenoxyethane, 1- (3,4-dimethylphenoxy)- 2-phenoxyethane, 1- (4-ethylphenoxy) -2-phenoxyethane, 1- (4-isopropylphenoxy) -2-phenoxyethane, 1,2-bis (2-methylphenoxy) ethane, 1- (2 -Methylphenoxy) -2- (4-methylphenoxy) ethane, 1- (4-tert-butylphenoxy) -2- (2-methylphenoxy) ) Ethane, 1,2-bis (3-methylphenoxy) ethane, 1- (3-methylphenoxy) -2- (4-methylphenoxy) ethane, 1- (4-ethylphenoxy) -2- (3-methyl) Phenoxy) ethane, 1,2-bis (4-methylphenoxy) ethane, 1- (2,3-dimethylphenoxy) -2- (4-methylphenoxy) ethane, 1- (2,5-dimethylphenoxy) -2 -(4-methylphenoxy) ethane, phenoxyacetic acid-2-naphthyl, 2-naphthoxyacetic acid-4-methylphenyl, 2-naphthoxyacetic acid-3-methylphenyl, 1-benzyloxynaphthalene, 2-benzyloxynaphthalene, 2- p-chlorobenzyloxynaphthalene, 2-p-isopropylbenzyloxynaphthalene, 2-dodecyloxynaphthalene, 2-de Noyloxynaphthalene, 2-myristoyloxynaphthalene, 2-p-tert-butylbenzoyloxynaphthalene, 2-benzoyloxynaphthalene, 2-benzyloxy-3-N- (3-dodecyloxypropyl) carbamoylnaphthalene, 2-benzyloxy -3-N-octylcarbamoylnaphthalene, 2-benzyloxy-3-dodecyloxycarbonylnaphthalene, 2-benzyloxy-3-p-tert-butylphenoxycarbonylnaphthalene, bisbenzyl oxalate, bis (p-methylbenzyl) oxalate Bis (p-chlorobenzyl) oxalate, bis (m-methylbenzyl) oxalate, bis (p-ethylbenzyl) oxalate, bis (p-methoxybenzyl) oxalate, bis (2-phenoxyethyl) oxalate , Bis oxalate ( 2-o-chlorophenoxyethyl), bis (2-p-chlorophenoxyethyl) oxalate, bis (2-p-ethylphenoxyethyl) oxalate, bis (2-m-methoxyphenoxyethyl) oxalate, oxalic acid Bis (2-p-methoxyphenoxyethyl), bis (4-phenoxybutyl) oxalate, 1,2-bisphenoxymethylbenzene, 1,3-bisphenoxymethylbenzene, 1,4-bis (2-methylphenoxymethyl) ) Benzene, 1,4-bis (3-methylphenoxymethyl) benzene, 1,3-bis (4-methylphenoxymethyl) benzene, 1,3-bis (2,4-dimethylphenoxymethyl) benzene, 1,3 -Bis (2,6-dimethylphenoxymethyl) benzene, 1,4-bis (2-chlorophenoxymethyl) benzene 1,2-bis (4-chlorophenoxymethyl) benzene, 1,3-bis (4-chlorophenoxymethyl) benzene, 1,2-bis (4-octylphenoxymethyl) benzene, 1,3-bis (4- Octylphenoxymethyl) benzene, 1,3-bis (4-isopropylphenylphenoxymethyl) benzene, 1,4-bis (4-isopropylphenylphenoxymethyl) benzene, and the like.

The above hot-melt materials can be used alone or in combination. The blending amount of the heat-meltable substance in the entire image forming layer is preferably 0.5 to 50% by mass with respect to the total solid content of the entire image forming layer. Further, the content ratio of the heat-meltable substance to the water-soluble polymer compound in the image forming layer (A) is preferably higher than the content ratio in the image forming layer (B).

These hot melt materials are solid materials at room temperature. In order to increase the reactivity due to heat, it is preferable to use these hot-melt materials after being finely dispersed. The fine dispersion treatment can be performed by a wet dispersion method generally used at the time of producing a paint, and for example, a bead mill such as a roll mill, a colloid mill, a ball mill, an attritor, and a sand mill can be used. As beads in the bead mill, ceramic beads such as zirconia, titania, and alumina, metal beads such as chrome and steel, glass beads, and the like can be used. The dispersed particle diameter of the hot-melt material obtained by the fine dispersion treatment is preferably from 0.1 to 1.2 μm, more preferably from 0.3 to 0.8 μm in terms of median diameter. The median diameter is the particle diameter (cumulative average diameter) at which the cumulative curve becomes 50% when the total curve of one population of particles is 100%, and the particle size distribution is evaluated. As one of the parameters to be measured, it can be measured using a laser diffraction / scattering particle size distribution measuring apparatus LA920 (manufactured by Horiba, Ltd.) or the like.

In the image forming layer of the heat-sensitive lithographic printing plate of i), a developer such as a phenol derivative or an aromatic carboxylic acid derivative used for general heat-sensitive recording paper or pressure-sensitive recording paper is used for ensuring visibility. A color former (electron-donating dye precursor) can be contained.

Specific examples of the developer include 4-cumylphenol, hydroquinone monobenzyl ether, 4,4′-isopropylidenediphenol, 1,1-bis (4-hydroxyphenyl) cyclohexane, 4,4′- Dihydroxydiphenyl-2,2-butane, 4,4′-dihydroxydiphenylmethane, 2,2-bis (4-hydroxyphenyl) -4-methylpentane, 2,2-bis (4-hydroxyphenyl) heptane, bis (4 -Hydroxyphenylthioethoxy) methane, 1,5-di (4-hydroxyphenylthio) -3-oxapentane, 1,1-bis (4-hydroxyphenyl) -1-phenylethane, 1,4-bis [α -Methyl-α- (4'-hydroxyphenyl) ethyl] benzene, 1,3-bis [α-methyl-α- (4'-hydride) Xylphenyl) ethyl] benzene, 4,4'-dihydroxydiphenyl sulfide, di (4-hydroxy-3-methylphenyl) sulfone, 4-hydroxy-4'-methyldiphenylsulfone, 4-hydroxy-4'-isopropoxydiphenylsulfone 2,4'-dihydroxydiphenylsulfone, 4,4'-dihydroxydiphenylsulfone, bis (3-allyl-4-hydroxyphenyl) sulfone, 4-hydroxyphenyl-4'-benzyloxyphenylsulfone, 4-hydroxy-3 ', 4'-tetramethylenebiphenylsulfone, 3,4-dihydroxyphenyl-p-tolylsulfone, 4,4'-dihydroxybenzophenone, benzyl 4-hydroxybenzoate, N, N'-di-m-chlorophenylthiourea, N- (phenoxy Phenolic compounds such as (ciethyl) -4-hydroxyphenylsulfonamide; zinc 4- [3- (p-tolylsulfonyl) propyloxy] salicylate, 4- [2- (p-methoxyphenoxy) ethyloxy] zinc salicylate, 5- [P- (2-p-methoxyphenoxyethoxy) cumyl] zinc salts of aromatic carboxylic acids such as zinc salicylate and zinc p-chlorobenzoate; and organic acidic substances such as antipyrine complexes of zinc thiocyanate The

Specific examples of the color former (electron-donating dye precursor) include (1) 3,3′-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide as a triarylmethane compound. (Crystal violet lactone), 3,3'-bis (p-dimethylaminophenyl) phthalide, 3- (p-dimethylaminophenyl) -3- (1,2-dimethylindol-3-yl) phthalide, 3 -(P-dimethylaminophenyl) -3- (2-methylindol-3-yl) phthalide, 3- (p-dimethylaminophenyl) -3- (2-phenylindol-3-yl) phthalide, 3,3 -Bis (1,2-dimethylindol-3-yl) -5-dimethylaminophthalide, 3,3-bis (1,2-dimethylindol-3-yl) -6- Methylaminophthalide, 3,3-bis (9-ethylcarbazol-3-yl) -5-dimethylaminophthalide, 3,3-bis (2-phenylindol-3-yl) -5-dimethylaminophthalide 3-p-dimethylaminophenyl-3- (1-methylpyrrol-2-yl) -6-dimethyl-aminophthalide, etc .; (2) 4,4'-bis-dimethylaminobenzhydrin benzyl as diphenylmethane compounds Ethers, N-halophenyl leucooramines, N-2,4,5-trichlorophenyl leucooramines, etc .; (3) as xanthene compounds, rhodamine B-anilinolactam, rhodamine Bp-nitroanilinolactam, Rhodamine Bp-chloroanilinolactam, 3-diethylamino-7-dibenzylaminofluora 3-diethylamino-7-octylaminofluorane, 3-diethylamino-7-phenylfluorane, 3-diethylamino-7- (3,4-dichloroanilino) fluorane, 3-diethylamino-7- (2-chloroanilino) Fluorane, 3-diethylamino-6-methyl-7-anilinofluorane, 3-dibutylamino-6-methyl-7-anilinofluorane, 3-piperidino-6-methyl-7-anilinofluorane, 3- Ethyl-tolylamino-6-methyl-7-anilinofluorane, 3-ethyl-tolylamino-6-methyl-7-phenethylfluorane, 3-diethylamino-7- (4-nitroanilino) fluorane, etc .; (4) thiazine Benzoyl leucomethylene blue, p-nitrobenzoyl leucomethylene blue (5) As spiro compounds, 3-methyl-spiro-dinaphthopyrans, 3-ethyl-spiro-dinaphthopyrans, 3,3'-dichloro-spiro-dinaphthopyrans, 3-benzyl-spiro-dinaphthopyrans, 3-methylnaphtho- (3-methoxy-benzo) -spiropyran, 3-propyl-spiro-dibenzopyran and the like. These may be used alone or in combination of two or more.

Furthermore, the image forming layer can also contain a photothermal conversion substance. By including the photothermal conversion agent, writing with active light such as an infrared laser as well as a thermal head is possible. As an example of the photothermal conversion substance, a material that efficiently absorbs light and converts it into heat is preferable. Depending on the light source used, for example, when a semiconductor laser emitting near infrared light is used as the light source, the photothermal conversion substance is preferably a near infrared light absorber having an absorption band in the near infrared, for example , Carbon black, cyanine dyes, polymethine dyes, azurenium dyes, squalium dyes, thiopyrylium dyes, naphthoquinone dyes, anthraquinone dyes and other organic compounds, phthalocyanine, azo, thioamide organic metal complexes, or Examples thereof include metal compounds such as iron powder, graphite powder, iron oxide powder, lead oxide, silver oxide, chromium oxide, iron sulfide, and chromium sulfide.

The coating amount of the entire image forming layer of the heat-sensitive lithographic printing plate i) is 0.5 to 30 g / dry solids from the viewpoints of printing durability of the image area, water resistance of the non-image area and mechanical strength. m ² is preferable.

Next, the image forming layer of the heat-sensitive lithographic printing plate that satisfies the requirements of ii) will be described. The heat-sensitive lithographic printing plate of ii) has at least two image-forming layers containing a water-soluble polymer compound and a thermoplastic resin on a water-resistant support, and is more water-resistant than the image-forming layer (B). The ratio of at least one compound selected from the compounds represented by the following general formulas (1) to (4) to the water-soluble polymer compound in the image forming layer (A) close to (that is, the general formulas (1) to ( The mass of at least one compound selected from the compounds represented by 4) / the mass of the water-soluble polymer compound) is higher than the ratio in the image forming layer (B) farthest from the water-resistant support. By providing such an image-forming layer of at least two layers on a water-resistant support, in addition to sufficient printing durability and soil resistance (water retention), printing defects due to head debris and image disturbance due to sticking phenomenon It is possible to provide a heat-sensitive lithographic printing plate having an improved

The heat-sensitive lithographic printing plate of ii) has a good printing durability and stain resistance (water retention), and further has improved printing defects due to head debris and image disturbance due to sticking phenomenon. The reason why is obtained is not clear, but is estimated as follows.

The heat-sensitive lithographic printing plate of ii) has an image forming layer on a water-resistant support that is converted to hydrophobicity by utilizing phase conversion by heat. Here, the layer to be converted to hydrophobic means that when heat is applied, part of the layer is melted and converted to hydrophobic, and the portion to which heat is not applied retains the hydrophilicity of the original layer. Yes. More specifically, when heat is applied, a part of the image forming layer melts and becomes hydrophobic, so that the thermoplastic resin embedded in the water-soluble polymer compound oozes out on the surface of the layer to make it hydrophobic. Sex is expressed. On the other hand, the non-printed portion, that is, the non-image portion does not exhibit hydrophobicity because the thermoplastic resin remains buried in the water-soluble polymer compound. In this way, there is a difference in hydrophobicity / hydrophilicity between the image area and the non-image area. In order to improve the printing durability and background stain resistance (water retention) of such a heat-sensitive lithographic printing plate, it is important to maintain this difference sufficiently even during printing. In the present invention, the hydrophilicity of the surface is reduced by reducing the ratio of the compounds represented by the general formulas (1) to (4) to the water-soluble polymer compound in the image forming layer (B) farthest from the water-resistant support. The water retention at the time of printing is improved, and at the same time, the hydrophobicity of the image area, which is reduced by this, is lower than that of the compounds represented by the general formulas (1) to (4) rather than the image forming layer (B). It can be overcome by providing an image forming layer (A) having a high ratio and close to a water-resistant support. As a result, when an image is formed by applying heat, the melting start temperature of the thermoplastic resin in the image forming layer (A) is lowered, melted with less energy, and oozed out on the surface of the image portion, thereby achieving high printing durability and durability. It is presumed that both soiling properties (water retention) can be achieved. Furthermore, as a heat-sensitive lithographic printing plate used in a plate making method for direct heat drawing, by adding the compounds represented by the general formulas (1) to (4) to the image forming layer, the thermoplastic resin of the image forming layer is added. The melting start temperature is lowered, sticking is improved, and general formulas (1) to (4) for the water-soluble polymer compound in the image forming layer (B) farthest from the water-resistant support in direct contact with the thermal head are shown. By reducing the ratio of the compound, an extremely excellent effect of improving the image disturbance due to the head residue can be obtained.

The ratio of the compounds represented by the general formulas (1) to (4) to the water-soluble polymer compound in the image forming layer (A) in ii) is higher than that in the image forming layer (B). There is no limitation on the method for producing the heat-sensitive lithographic printing plate to be used. For example, a method of applying the image forming layer (A) and then applying the image forming layer (B) sequentially and stacking, or a slide hopper method And a method of applying multiple layers simultaneously.

Ii) The image forming layer of the thermosensitive lithographic printing plate contains at least one selected from the compounds represented by the general formulas (1) to (4). The compound represented by the general formula (1) will be described below.

In the above formula, X ₁ represents —O— or —CO—O—,
R ₁ , R ₂ and R ₃ each independently represent a hydrogen atom, an alkyl group or an aryl group, or R ₁ , R ₂ and R ₃ may be bonded to each other to form an aromatic ring. ,
R ₄ , R ₅ and R ₆ each independently represent a hydrogen atom, an alkyl group or an aryl group, or R ₄ , R ₅ and R ₆ may be bonded to each other to form an aromatic ring. ,
n represents an integer of 1 to 10.

In a preferred embodiment of the present invention, the compound represented by the general formula (1) is a compound in which X ₁ is —O—. In a more preferred embodiment of the present invention, in the compound represented by the general formula (1), R ₁ and R ₆ are a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and R ₂ , R ₃ , R ₄ and R _A compound in which ₅ is a hydrogen atom and n is an integer of 1 to 4.

Examples of the compound represented by the general formula (1) include the following compounds, but the present invention is not limited to these:
(1) 1- (1-naphthoxy) -2-phenoxyethane;
(2) 1- (2-naphthoxy) -4-phenoxybutane;
(3) 1- (2-isopropylphenoxy) -2- (2-naphthoxy) ethane;
(4) 1- (4-methylphenoxy) -3- (2-naphthoxy) propane;
(5) 1- (2-methylphenoxy) -2- (2-naphthoxy) ethane;
(6) 1- (3-methylphenoxy) -2- (2-naphthoxy) ethane;
(7) 1- (2-naphthoxy) -2-phenoxyethane;
(8) 1- (2-naphthoxy) -6-phenoxyhexane;
(9) 1-phenoxy-2- (2-phenylphenoxy) ethane;
(10) 1- (2-methylphenoxy) -2- (4-phenylphenoxy) ethane;
(11) 1,4-diphenoxybutane;
(12) 1,4-bis (4-methylphenoxy) butane;
(13) 1,2-di (3,4-dimethylphenoxy) ethane;
(14) 1-phenoxy-3- (4-phenylphenoxy) propane;
(15) 1- (4-tert-butylphenoxy) -2-phenoxyethane;
(16) 1,2-diphenoxyethane;
(17) 1- (4-methylphenoxy) -2-phenoxyethane;
(18) 1- (2,3-dimethylphenoxy) -2-phenoxyethane;
(19) 1- (3,4-dimethylphenoxy) -2-phenoxyethane;
(20) 1- (4-ethylphenoxy) -2-phenoxyethane;
(21) 1- (4-Isopropylphenoxy) -2-phenoxyethane;
(22) 1,2-bis (2-methylphenoxy) ethane;
(23) 1- (2-methylphenoxy) -2- (4-methylphenoxy) ethane;
(24) 1- (4-tert-butylphenoxy) -2- (2-methylphenoxy) ethane;
(25) 1,2-bis (3-methylphenoxy) ethane;
(26) 1- (3-methylphenoxy) -2- (4-methylphenoxy) ethane;
(27) 1- (4-ethylphenoxy) -2- (3-methylphenoxy) ethane;
(28) 1,2-bis (4-methylphenoxy) ethane;
(29) 1- (2,3-dimethylphenoxy) -2- (4-methylphenoxy) ethane;
(30) 1- (2,5-dimethylphenoxy) -2- (4-methylphenoxy) ethane;
(31) Phenoxyacetic acid-2-naphthyl;
(32) 2-naphthoxyacetic acid-4-methylphenyl; and (33) 2-naphthoxyacetic acid-3-methylphenyl.

Next, the compound represented by the general formula (2) will be described.

In the above formula, R ₇ represents an alkyl group, an aryl group, an alkylcarbonyl group, an arylcarbonyl group, an alkylsulfonyl group or an arylsulfonyl group. The naphthalene ring in the formula may further have a substituent, and examples of preferable substituents include an alkyl group, an aryl group, a halogen atom, a hydroxy group, an alkoxy group, an aryloxy group, and an alkyloxycarbonyl group. , Alkoxycarbonyl group, aryloxycarbonyl group, carbamoyl group, sulfamoyl group and the like.

In a preferred embodiment of the present invention, in the compound of the general formula (2), R ₇ is an alkyl group having 4 to 20 carbon atoms, an aryl group having 4 to 24 carbon atoms, an alkylcarbonyl group having 2 to 20 carbon atoms, or a carbon atom. A compound which is an arylcarbonyl group of formula 7-20. In a more preferred embodiment of the present invention, in the compound of the above general formula (2), the substituent that the naphthalene ring may further have is a halogen atom, an alkyl group having 1 to 10 carbon atoms, or a group having 2 to 20 carbon atoms. The compound is an alkyloxycarbonyl group, an aryloxycarbonyl group having 7 to 20 carbon atoms, or a carbamoyl group having 2 to 25 carbon atoms.

Examples of the compound represented by the general formula (2) include the following compounds, but the present invention is not limited to these:
(1) 1-benzyloxynaphthalene;
(2) 2-Benzyloxynaphthalene:
(3) 2-p-chlorobenzyloxynaphthalene;
(4) 2-p-isopropylbenzyloxynaphthalene;
(5) 2-dodecyloxynaphthalene;
(6) 2-decanoyloxynaphthalene;
(7) 2-Myristoyloxynaphthalene;
(8) 2-p-tert-butylbenzoyloxynaphthalene;
(9) 2-benzoyloxynaphthalene;
(10) 2-Benzyloxy-3-N- (3-dodecyloxypropyl) carbamoylnaphthalene;
(11) 2-Benzyloxy-3-N-octylcarbamoylnaphthalene;
(12) 2-benzyloxy-3-dodecyloxycarbonylnaphthalene; and (13) 2-benzyloxy-3-p-tert-butylphenoxycarbonylnaphthalene.

Next, the compound represented by the general formula (3) will be described.

In the above formula, R ₈ and R ₉ each independently represent a hydrogen atom, a halogen atom, an alkyl group having 1 to 4 carbon atoms or an alkoxy group having 1 to 4 carbon atoms,
X ₂ represents a single bond or —O—,
n represents an integer of 1 to 4.

Examples of the compound represented by the general formula (3) include the following compounds, but the present invention is not limited to these:
(1) Bisbenzyl oxalate;
(2) bis (p-methylbenzyl) oxalate;
(3) Bis oxalate (p-chlorobenzyl);
(4) bis (m-methylbenzyl) oxalate;
(5) Bis oxalate (p-ethylbenzyl);
(6) bis (p-methoxybenzyl) oxalate;
(7) bis (2-phenoxyethyl) oxalate;
(8) Bis (2-o-chlorophenoxyethyl) oxalate;
(9) Bis (2-p-chlorophenoxyethyl) oxalate;
(10) Bis (2-p-ethylphenoxyethyl) oxalate;
(11) bis (2-m-methoxyphenoxyethyl) oxalate;
(12) bis (2-p-methoxyphenoxyethyl) oxalate; and (13) bis (4-phenoxybutyl) oxalate.

Preferred examples of these exemplary compounds include bisbenzyl oxalate, bis (p-methylbenzyl) oxalate, bis (p-chlorobenzyl) oxalate, bis (m-methylbenzyl) oxalate, and bisoxalate. (P-ethylbenzyl), and bis (p-methoxybenzyl) oxalate.

Hereinafter, the compound represented by the general formula (4) will be described.

In the above formula, R ₁₀ , R _{10 ′} , R ₁₁ and R _{11 ′} each independently represent a hydrogen atom, a halogen atom, an alkyl group, an aryl group, an alkoxy group, an alkylcarbonyl group, an arylcarbonyl group or an alkoxycarbonyl group. Or an aryloxy group is shown.

Examples of the compound represented by the general formula (4) include the following compounds, but the present invention is not limited to these:
(1) 1,2-bisphenoxymethylbenzene;
(2) 1,3-bisphenoxymethylbenzene:
(3) 1,4-bis (2-methylphenoxymethyl) benzene;
(4) 1,4-bis (3-methylphenoxymethyl) benzene;
(5) 1,3-bis (4-methylphenoxymethyl) benzene;
(6) 1,3-bis (2,4-dimethylphenoxymethyl) benzene;
(7) 1,3-bis (2,6-dimethylphenoxymethyl) benzene;
(8) 1,4-bis (2-chlorophenoxymethyl) benzene;
(9) 1,2-bis (4-chlorophenoxymethyl) benzene;
(10) 1,3-bis (4-chlorophenoxymethyl) benzene;
(11) 1,2-bis (4-octylphenoxymethyl) benzene;
(12) 1,3-bis (4-octylphenoxymethyl) benzene;
(13) 1,3-bis (4-isopropylphenylphenoxymethyl) benzene; and (14) 1,4-bis (4-isopropylphenylphenoxymethyl) benzene.

Among these exemplified compounds, preferred specific examples include 1,2-bisphenoxymethylbenzene, 1,4-bis (2-methylphenoxymethyl) benzene, 1,4-bis (3-methylphenoxymethyl) benzene, And 1,4-bis (2-chlorophenoxymethyl) benzene. The compounding amount of the compounds represented by the general formulas (1) to (4) in the entire image forming layer is preferably 30 to 130% by mass with respect to the amount of the thermoplastic resin in the entire image forming layer. This compound may be used alone or in combination with other heat-meltable substances.

The compounds represented by the general formulas (1) to (4) are solid substances at room temperature. In order to increase the reactivity due to heat, these compounds are preferably used after being finely dispersed. The fine dispersion treatment can be performed by a wet dispersion method generally used at the time of producing a paint, and for example, a bead mill such as a roll mill, a colloid mill, a ball mill, an attritor, and a sand mill can be used. As beads in the bead mill, ceramic beads such as zirconia, titania and alumina, metal beads such as chrome and steel, glass beads and the like can be used. The dispersed particle diameter of the compound obtained by the fine dispersion treatment is preferably from 0.1 to 1.2 μm, more preferably from 0.3 to 0.8 μm in terms of median diameter. The median diameter is the particle diameter (cumulative average diameter) at which the cumulative curve becomes 50% when the total curve of one population of particles is 100%, and the particle size distribution is evaluated. As one of the parameters to be measured, it can be measured using a laser diffraction / scattering particle size distribution measuring apparatus LA920 (manufactured by Horiba, Ltd.) or the like.

Ratio of compounds represented by general formulas (1) to (4) to water-soluble polymer compounds in the image forming layer (B) farthest from the water-resistant support (compounds represented by general formulas (1) to (4)) (Mass / water soluble polymer compound) is preferably 0 to 0.5. Further, the ratio of the compounds represented by the general formulas (1) to (4) to the water-soluble polymer compound in the image forming layer (A) close to the water-resistant support (the compounds represented by the general formulas (1) to (4)) (Mass / water-soluble polymer compound) is preferably 1.0 or more.

In the heat-sensitive lithographic printing plate of ii), the ratio of the compounds represented by the general formulas (1) to (4) to the water-soluble polymer compound in the image forming layer (A) is more than the ratio in the image forming layer (B). However, the difference between the ratio in the image forming layer (A) and the ratio in the image forming layer (B) is preferably 1.0 or more.

In the thermosensitive planographic printing plate of ii), when three image forming layers are provided, an image forming layer (C) may be provided between the image forming layer (A) and the image forming layer (B). The ratio of the compounds represented by the general formulas (1) to (4) to the water-soluble polymer compound in the image forming layer (C) may be higher or lower than that in the image forming layer (B). It is preferably lower than the ratio in the image forming layer (A) and higher than the ratio in the image forming layer (B).

Ii) The image forming layer of the heat-sensitive lithographic printing plate contains a thermoplastic resin. Examples of the thermoplastic resin include those similar to the thermoplastic resin contained in the image forming layer of the heat-sensitive lithographic printing plate of i) described above in the present specification. These thermoplastic resins can be used alone or in combination of two or more. In view of the affinity with the printing ink vehicle (binder component), the thermoplastic resin is preferably a synthetic rubber latex, and particularly preferably a styrene-butadiene copolymer and a modified product thereof. The blending amount of the thermoplastic resin in the entire image forming layer is preferably 5 to 50% by mass with respect to the solid content of the entire image forming layer.

Further, in order to easily develop the effect of melting and fusing by heat, the glass transition temperature of the thermoplastic resin is preferably 50 to 150 ° C., more preferably 55 to 120 ° C. If the glass transition temperature is less than 50 ° C., a phase change occurs in the liquid state during the production process, and hydrophobicity is developed even in the non-image area, which may cause printing stains. Further, when the glass transition temperature exceeds 150 ° C., the polymer is hardly melted by heat, and it may be difficult to form a strong image with a relatively small output laser or a small thermal printer.

Ii) The image forming layer of the heat-sensitive lithographic printing plate contains a water-soluble polymer compound. Examples of the water-soluble polymer compound include those similar to the water-soluble polymer compound contained in the image forming layer of the heat-sensitive lithographic printing plate of i). The water-soluble polymer compound may be used alone or in combination of two or more. In particular, gelatin and polyvinyl alcohol rich in film formation and modified products thereof are preferably selected for maintaining the hydrophilicity of the non-image area. The blending amount of the water-soluble polymer compound in the entire image forming layer is preferably 0.5 to 50% by mass with respect to the total solid content of the entire image forming layer.

In order to improve the water resistance and mechanical strength of the non-image area, the image forming layer preferably contains a hardening agent (waterproofing agent) depending on the type of the water-soluble polymer compound. Examples of the hardener used include those similar to the hardener contained in the image forming layer of the heat-sensitive lithographic printing plate i) described above. When the water-soluble polymer compound is gelatin, divinyl sulfone is preferably used as the hardener, and when the water-soluble polymer compound is polyvinyl alcohol, glyoxal is preferably used as the hardener. The blending amount of the hardener in the entire image forming layer is preferably 0.01 to 30% by mass, more preferably 5 to 5% by weight based on the solid content of the water-soluble polymer compound contained in the entire image forming layer. 30% by mass.

In addition to the compounds represented by the general formulas (1) to (4), the image forming layer of the heat-sensitive lithographic printing plate of ii) can contain a hot-melt material. As the hot-melt material, an organic compound having a melting point of 50 to 150 ° C. is preferable. For example, waxes such as carnauba wax, microcrystalline wax, paraffin wax, polyethylene wax, lauric acid, stearic acid, oleic acid, palmitic acid, behen Acids, fatty acids such as montanic acid, and esters and amides thereof can be used. The blending amount of the heat-meltable substance in the entire image forming layer is preferably 0.5 to 50% by mass with respect to the total solid content of the image forming layer.

In the heat-sensitive lithographic printing plate of ii), in order to ensure visibility, a developer or a color former (electron donor) such as a phenol derivative or an aromatic carboxylic acid derivative used in general heat-sensitive recording paper and pressure-sensitive recording paper. Dye precursor). Specific examples of the color developer and color former include those similar to the color developer and color developer contained in the image forming layer of the heat-sensitive lithographic printing plate i) described above.

Furthermore, a photothermal conversion substance can be added to the image forming layer of the heat-sensitive lithographic printing plate of ii). By using a photothermal conversion agent, writing with active light such as an infrared laser as well as a thermal head is possible. Examples of the photothermal conversion material include the same photothermal conversion materials as those contained in the image forming layer of the heat-sensitive lithographic printing plate i) described above.

The coating amount of the entire image forming layer of the heat-sensitive lithographic printing plate of ii) is 0.5 to 30 g / in dry solid content from the viewpoints of printing durability of the image area, water resistance of the non-image area and mechanical strength. m ² is preferable.

The image forming layer (B) farthest from the water-resistant support of the heat-sensitive lithographic printing plate that satisfies the above requirements i) and / or ii) can contain zinc oxide or barium sulfate. As a result, it is possible to provide a heat-sensitive lithographic printing plate in which printing durability and background stain resistance (water retention) are improved in a balanced manner.

<Zinc oxide>
Zinc oxide is roughly classified into a dry method and a wet method according to its production method. There are a French method and an American method in the dry method, and a German method is well known as the wet method. The French method is a method in which zinc oxide is produced by heating high-purity metallic zinc and combusting generated zinc vapor in an oxidizing atmosphere. On the other hand, the American method is a method in which a reducing agent such as coke is added to zinc ore (flankite) and roasted, and the generated zinc vapor is oxidized by air to produce it. Further, the wet method includes a method of thermally decomposing a zinc salt such as zinc carbonate, a method of directly depositing zinc oxide in a solution while neutralizing an alkaline solution of the zinc salt with an acid, an acidic solution of the zinc salt There is a method of direct precipitation in the liquid while neutralizing the solution. In general, it is produced by reacting an acidic solution of zinc salt (zinc sulfate solution or zinc chloride solution) with an alkali such as soda ash, washing with water, filtering and drying, firing and pulverizing. Zinc oxide produced by these methods is commercially available from, for example, Shodo Chemical Co., Ltd., Sakai Chemical Co., Ltd., Hakusui Tech Co., Ltd., Honjo Chemical Co., Ltd., Toho Zinc Co., Ltd. Any of these can be used in the present invention.

<Barium sulfate>
Barium sulfate is barium sulfate obtained by pulverizing barite and removing iron, washing with water, and sedimentation produced by adding a sulfate aqueous solution to a barium chlorine solution and chemically precipitating. And barium sulfate. Examples of the barium sulfate produced by these methods include those commercially available from Sakai Chemical Co., Ltd., Takehara Chemical Industry Co., Ltd., Hakusuikku Co., Ltd., etc. Can be used. Furthermore, barium sulfate may be subjected to organic polymer treatment as a post-treatment after particle formation, and may be a hydroxide or oxide of any metal element such as Al, Si and Zr, or Mg, Ca, Sr. And surface treatment may be performed with a phosphate or the like of any of metal elements such as Ba.

When the average particle diameter of zinc oxide or barium sulfate is too large, the contact area may decrease when printing is performed by directly contacting the image forming layer (B) with a thermal head. The reduction of the contact area may lead to a decrease in thermal efficiency and a decrease in printing durability. On the other hand, if the average particle size of zinc oxide or barium sulfate is too small, the effect on printing durability and soil resistance (water retention) is naturally reduced, but depending on the particle size of zinc oxide or barium sulfate. In the case where the contact area is excessively enlarged, the sticking resistance may be lowered due to a decrease in peelability or the like. Therefore, the average particle diameter of zinc oxide or barium sulfate used in the present invention is preferably in the range of 0.1 to 1.0 μm, more preferably 0.2 to 0.5 μm.

The shape of zinc oxide or barium sulfate used in the present invention may be any of an irregular shape, a plate shape, a columnar shape, and a granular shape, but an irregular shape is preferred.

The content of zinc oxide or barium sulfate contained in the image forming layer (B) is preferably 8 to 26% by mass with respect to the amount of the thermoplastic resin contained in the image forming layer (B). Thereby, it is possible to achieve both printing durability and ground stain resistance (water retention) at a higher level. Further, it is desirable to use zinc oxide or barium sulfate in an amount not exceeding the range of 5% by mass or less with respect to the total amount of the thermoplastic resin contained in the image forming layer (A) and the image forming layer (B).

<Undercoat layer>
In the present invention, an undercoat layer containing at least titanium dioxide, a binder resin and a crosslinking agent having an average particle size smaller than the average dry film thickness of the undercoat layer is provided between the image forming layer (A) and the water-resistant support. be able to. As a result, it is possible to provide a heat-sensitive lithographic printing plate that does not require any so-called debris processing in an ablation method, an on-machine development method, or the like, with improved scratch resistance without deteriorating image quality and printing durability.

Scratch resistance in the present invention is effective not only for surface scratches and the like which are introduced in the production process and plate making process of the lithographic printing plate, but also for quality deterioration due to scratches generated during printing. A scratch generated during printing is a partial change in plate pressure caused by a slight undulation formed on a blanket roller of a printing press, resulting in poor printability by scratching the plate surface. This partial plate pressure change is particularly likely to occur at the portion where the blanket bends in the vicinity of the cylinder gripping portion of the printing press, and appears on the printing paper as dirt at the extreme tip and the bottom edge. As used herein, this soil is referred to as “bran scratch” and resistance to this soil is also referred to as “bran scratch resistance”.

The titanium dioxide used for the undercoat layer may be either a rutile type or an anatase type. Further, the production method is not limited to either the sulfuric acid method or the chlorine method, and they may be used alone or in combination. Furthermore, from the viewpoint of dispersion stability and other functionality, it is possible to selectively use those subjected to various surface treatments. As the surface treatment composition, alumina, silica, zinc oxide, zirconia and the like are common. Examples of commercially available titanium dioxide include SR-1, R-650, R-5N, R-7E, R-3L, A-110, and A-190 from Sakai Chemical Industry Co., Ltd. ), Typeke R-580, R-930, A-100, A-220, CR-58, etc., from Titanium Industry Co., Ltd., Kronos KR-310, KR-380, KA-10 KA-20 etc., from Teika Co., Ltd., Titanics JR-301, JR-600A, JR-800, JR-701 etc., from DuPont Co., Ltd., Taipure R-900, R-931 Etc.

The average particle diameter of titanium dioxide used in the present invention is preferably smaller than the average dry film thickness of the undercoat layer. Titanium dioxide generally exists in the form of secondary particles, tertiary particles, etc., with some primary particles agglomerated. The average particle diameter of the titanium dioxide is, for example, titanium dioxide in a dispersion medium to which a dispersant such as polycarboxylic acid, fatty acid amine, sulfonic acid amide, ε-caprolactone, hydrostearic acid, polyester amine is added. Is dispersed using a media mill such as a ball mill, a bead mill, a sand grinder, a pressure disperser such as a high pressure homogenizer, an ultra high pressure homogenizer, an ultrasonic disperser, and a thin film swirl disperser. It is preferable to adjust appropriately. The average particle diameter of titanium dioxide in the undercoat layer is preferably from 0.1 to 1.5 μm, and more preferably from 0.3 to 1.0 μm. The average particle diameter of titanium dioxide can be measured as a number median diameter using a laser scattering particle size distribution meter (for example, LA920 manufactured by Horiba, Ltd.).

The content of titanium dioxide used in the undercoat layer of the present invention can be set within a wide range, but it should be used at 200 to 1000% by mass with respect to 100 parts by mass of the binder resin solid content contained in the undercoat layer. Is more preferable, and 400 to 600% by mass is more preferable. When the content of titanium dioxide is small, the water retention may be lowered or the effect on scratch resistance may not be recognized. When titanium dioxide is used in excess, for example, the stability of the coating solution may decrease, the bulk density may increase due to irregular aggregation, etc., and the surface roughness may increase, or the printability may decrease. .

As the binder resin contained in the undercoat layer of the present invention, for example, gelatin such as lime-processed gelatin, acid-processed gelatin, and enzyme-processed gelatin, water-soluble polymers such as polysaccharides, polyvinyl alcohol, and polyvinylpyrrolidone can be used. It is particularly preferable to use gelatin.

As the crosslinking agent contained in the undercoat layer of the present invention, for example, melamine resin, epoxy resin, polyisocyanate compound, aldehyde compound, silane compound, chromium alum, divinyl sulfone and the like can be suitably used, but the binder resin is gelatin. A particularly preferred cross-linking agent is divinyl sulfone. The amount of the crosslinking agent in the undercoat layer is preferably 1 to 30% by mass, more preferably 2 to 15% by mass, based on the solid content of the binder. As a method for adding the cross-linking agent, there are a method of adding a coating solution for the undercoat layer, a method of adding it in-line immediately before coating, and the like.

<Water resistant support>
As the water-resistant support used in the heat-sensitive lithographic printing plate of the present invention, a plastic film, resin-coated paper, water-resistant paper and the like can be used. Specifically, polyolefin films such as polyethylene and polypropylene, polyethersulfone, polyester, poly (meth) acrylate, polycarbonate, polyamide, and polyvinyl chloride, etc .; resin-coated paper with these plastics laminated or coated on the surface; melamine formaldehyde Paper that has been water-resistant with a wet paper strength agent such as a resin, urea formaldehyde resin, or epoxidized polyamide resin can be suitably used.

Next, a plate making method using the above-described heat-sensitive lithographic printing plate of the present invention will be described. The heat-sensitive lithographic printing plate of the present invention has a heat-sensitive image forming layer. In the heat-sensitive lithographic printing plate of the present invention, when the image forming layer contains a photothermal conversion substance, it is possible to form an image portion by irradiating light containing infrared light from 760 nm to 1200 nm, for example. Further, it is preferable to form the image portion with a solid-state laser and a semiconductor laser emitting infrared rays. In particular, laser exposure enables desired image-like recording directly from digital information of a computer. In the heat-sensitive lithographic printing plate of the present invention, it is also possible to draw an image forming layer directly by heat with a thermal head or a heat block to form an image portion. According to the thermal head, desired image-like recording can be performed directly from digital information of a computer. The heat-sensitive lithographic printing plate of the present invention can be printed without removing the image forming layer by the ablation method or the on-press development method after printing in this way.

When a thermal head is used, a line printer using a thick film or thin film line head, a serial printer using a thin film serial head, or the like can be used. The recording energy density is preferably 10 to 100 mJ / mm ² . In order to obtain a relatively high quality output image, the image recording density of the head is preferably 300 dpi or more.

The heat-sensitive lithographic printing plate of the present invention can be converted into ink acceptability or improved by any known surface treatment agent that has been suitably used in conventional lithographic printing plates. The printing method, or the desensitizing liquid and the moisturizing liquid to be used can be applied by a generally well-known method.

Hereinafter, the present invention will be described with reference to examples, but it is needless to say that the present invention is not limited to this description. In the following description, “%” and “part” indicate “% by mass” and “part by mass” unless otherwise specified.

Example 1
As shown in Table 1, the first layer (image forming layer (A)) and the second layer (as shown in Table 1) are coated on one side of a polyethylene-coated paper having a thickness of about 180 μm and laminated on both sides. to prepare a coating liquid of the image forming layer (B)), were simultaneously coated to a wet coating weight first layer 30 g / m 2, ^2-layer 10 g / m ² by a slide hopper coating method, dried An image forming layer was prepared and sample no. 1 to 13 thermosensitive lithographic printing plates were obtained.

The color former mixed slurry used for the image forming layer coating solution a was prepared in advance by the following constitution.
<Preparation of color former mixed slurry>
Material a: 1,2-bis (3-methylphenoxy) ethane (manufactured by Sanko Co., Ltd .: KS-232)
Material b: 4-hydroxy-4'-isopropoxydiphenyl sulfone (manufactured by Nippon Soda Co., Ltd .: D-8)
Material c: 3-dibutylamino-6-methyl-7-anilinofluorane (manufactured by Yamamoto Kasei Co., Ltd .: ODB2)

The materials a, b, and c are individually dispersed in a small dyno mill (bead mill) using a zirconia bead to an arbitrary particle size to prepare dispersions adjusted to a solid content concentration of about 30%, Dispersion a, dispersion b, and dispersion c were used. A color former mixed slurry was prepared by mixing 1 part of the dispersion c at room temperature with 3 parts of each of the dispersions a and b.

* The ratio represents the ratio (mass ratio) of the thermoplastic resin to the water-soluble polymer compound.
(Hot-melting resin (Y) / water-soluble polymer compound (X))

Also, as a comparison, a coating liquid prepared as shown in the following image forming layer coating liquid b formulation was applied to one side of a polyethylene-coated paper with a thickness of about 180 μm and laminated on both sides by the slide hopper coating method. The sample was applied in an amount of 60 g / m ² and dried. 14 heat-sensitive lithographic printing plates were obtained.

A test printing mode (printing speed 2 inch / sec, applied energy 18) of a direct thermal printer (barcode printer B-433 manufactured by TOSHIBA TEC CO., LTD .: line type thermal head 300 dpi) is applied to the heat-sensitive lithographic printing plate thus prepared. .6 mJ / mm ² ), an image was recorded, and a printing plate was produced.

As for printing durability, as for printing durability, HAMADAH234C (trademark of offset printing machine manufactured by Hamada Printing Co., Ltd.) is used as a printing machine, and ink is New Champion F Gloss Sumi N (trademark manufactured by DIC Corporation), supply. The dampening solution uses a 12% aqueous solution of SLM-OD (trademark of dampening solution manufactured by Mitsubishi Paper Industries Co., Ltd.). Before starting printing, wipe the plate surface thoroughly with dampening solution, and then evaluate under forced conditions. In order to achieve this, printing was started with a 0.1 mm gauge film sandwiched between the plate cylinder and the plate and the printing pressure increased. The number of printed images that were missing and could not be printed was evaluated according to the following evaluation criteria.
<Print durability>
A: More than 5,000 sheets O: 3,000 to less than 5,000 Δ: 1,000 to less than 3,000 x: Less than 1,000 results are shown in Table 2.

Printing evaluation for soil stain resistance (water retention) was carried out using Ryobi 3200CD (trademark made by Ryobi Imagics Co., Ltd.) as the printing machine, and ink as New Champion Purple 68N (trademark of ink produced by DIC Corporation), As the dampening solution, SLM-OD (trademark of dampening solution manufactured by Mitsubishi Paper Industries Co., Ltd.) 2% aqueous solution was used. Before starting printing, printing was started after wiping the entire plate surface with dampening solution. The number of stains (background stains) generated on the non-image area of the printed material was evaluated according to the following evaluation criteria.
<Soil stain resistance (water retention)>
A: More than 2,000 sheets O: 1,500 to less than 2,000 Δ: 1,000 to less than 1,500 sheets ×: Less than 1,000 results are shown in Table 2.

As can be seen from the results shown in Table 2, the ratio of the thermoplastic resin to the water-soluble polymer compound in the image-forming layer (A) close to the water-resistant support is the image-forming layer (B) farthest from the water-resistant support. It can be seen that when the ratio is higher than the ratio, good printing durability and soil resistance (water retention) can be obtained.

(Example 2)
The coating solution for the first layer (image forming layer (A)) as shown in Table 3 is applied to one side of a polyethylene-coated paper having a thickness of about 180 μm and laminated on both sides as shown in Table 3 below. Prepared, applied by a slide hopper coating method at a moisture application amount of 20 g / m ² , dried, and further coated with the second layer (image forming layer (C)) as shown in Table 3 in the image forming layer coating solution c formulation. A liquid is prepared, applied by a slide hopper coating method at a moisture application amount of 20 g / m ² , dried, and further, the third layer (image forming layer (B)) of the image forming layer coating liquid c formulation as shown in Table 3 A coating solution was prepared, applied by a slide hopper coating method at a moisture application amount of 20 g / m ² and dried to prepare an image forming layer. 15-18 thermosensitive lithographic printing plates were obtained. The color former mixed slurry used at this time was the sample No. described above. The same one was used. For comparison, the sample No. Fourteen thermosensitive lithographic printing plates were used. The thus produced thermosensitive lithographic printing plate was printed and evaluated in the same manner as in Example 1. The results are shown in Table 4.

As can be seen from the results shown in Table 4, even when three image forming layers were provided, the ratio of the thermoplastic resin to the water-soluble polymer compound in the image forming layer (A) close to the water resistant support was determined as the water resistant support. It can be seen that by making the ratio higher than that in the image forming layer (B) furthest away from the body, good printing durability and soil resistance (water retention) can be obtained.

(Example 3)
As shown in Table 5, the first layer (image forming layer (A)) and the second layer (with the following image forming layer coating solution d formulation) are coated on one side of a polyethylene-coated paper having a thickness of about 180 μm and laminated on both sides. to prepare a coating liquid of the image forming layer (B)), were simultaneously coated as a wet coating weight first layer 30 g / m 2, ^2-layer 10 g / m ² by a slide hopper coating method, dried An image forming layer was prepared and sample no. 19 to 25 thermosensitive lithographic printing plates were obtained. The compounds of general formulas (1) to (4), the developer, and the color former are individually dispersed in advance using a small dynomill (bead mill) with zirconia beads at a solid content concentration of 30%. Used in liquid form.

For comparison, a coating solution as shown in Table 5 was prepared, applied at a moisture application amount of 40 g / m ² by a slide hopper coating method, and then dried, and then a comparative sample (thermal lithographic printing plate of sample Nos. 26 and 27). ) Was produced.

A test printing mode (printing speed 2 inches / sec, applied energy 18) of a direct thermal printer (barcode printer B-433 manufactured by TOSHIBA TEC CO., LTD .: line type thermal head 300 dpi) is applied to the heat-sensitive lithographic printing plate thus produced. .6 mJ / mm ² ), an image was recorded, and a printing plate was produced.

Table 6 shows the results of the evaluation of head scum improvement, in which one-dot images printed with diagonal lines were continuously made into 50 plates, and the first plate and the 50th plate were visually inspected according to the following evaluation criteria.
<Head residue improvement>
○: No difference in image quality between the 1st and 50th plates.
X: There is a difference in image quality between the first plate and the 50th plate.
<Printing>
As for printing durability, an image for printing evaluation was made under the above-mentioned plate making conditions, and a printing test was conducted using this as a printing sample. The printing machine uses HAMADA DU342C (offset printing machine manufactured by Hamada Printing Machinery Co., Ltd.), the ink is New Champion F gloss ink 85N (manufactured by DIC Corporation), and the dampening liquid is SLM-OD30 (Mitsubishi Paper Co., Ltd.). Use a 10% aqueous solution of SLM-OD30 (Mitsubishi Paper Co., Ltd. moisturizing solution) before commencing printing, and then start printing after wiping the entire plate surface. did. As an evaluation of the improvement of the sticking phenomenon, the black solid portion of the printed material was confirmed by the presence or absence of white streaks generated in the direction perpendicular to the plate-making printing direction, and evaluated according to the following evaluation criteria. Further, as an evaluation of printing durability, the number of prints that could not be printed due to missing images was evaluated according to the following evaluation criteria.
<Improve sticking phenomenon>
○: White stripes are not seen.
X: White streaks are observed.
<Print durability>
A: 5,000 or more B: 3,000 to less than 5,000 Δ: 1,000 to less than 3,000 ×: Less than 1,000 results are shown in Table 6.

As for the soil resistance (water retention), an image for printing evaluation was made under the plate making conditions, and a printing test was performed using the image as a printing sample. The printer uses Ryobi 3200CD (manufactured by Ryobi Imagics Co., Ltd.), the ink is New Champion F Gloss Purple 68N (DIC Co., Ltd.), and the dampening solution is SLM-OD (Mitsubishi Paper Co., Ltd. dampening solution). ) Using a 2% aqueous solution, before starting printing, printing was started after using a 20% aqueous solution of SLM-OD30 (Mitsubishi Paper Co., Ltd. dampening solution) to wipe the entire plate surface. The number of stains (background stains) generated on the non-image area of the printed material was evaluated according to the following evaluation criteria.
<Soil stain resistance (water retention)>
◎: More than 2,000 sheets ○: 1,500 to less than 2,000 sheets △: 1,000 to less than 1,500 sheets ×: Less than 1,000 sheets Table 6 shows the results.

As can be seen from the results shown in Table 6, the ratio of the compounds represented by the general formulas (1) to (4) to the water-soluble polymer compound in the image-forming layer (A) close to the water-resistant support was determined using the water-resistant support. By making the ratio higher than that in the image forming layer (B) farthest from the image, in addition to sufficient printing durability and background stain resistance (water retention), printing defects due to head debris and image disturbance due to sticking phenomenon are caused. It can be seen that an improved thermal lithographic printing plate is obtained.

Example 4
As a result of performing the same test except that the compound of the general formulas (1) to (4) in Example 3 was 2-benzyloxynaphthalene, the same result as in Example 3 was obtained.

(Example 5)
As a result of testing in the same manner except that the compound of the general formulas (1) to (4) in Example 3 was bis (p-methylbenzyl) oxalate, the same result as in Example 3 was obtained.

(Example 6)
As a result of the same test except that the compound of the general formulas (1) to (4) in Example 3 was 1,2-bisphenoxymethylbenzene, the same result as in Example 3 was obtained.

(Example 7)
The image forming layer coating solution was the same except that 0.25 kg of carbon black: SD9020 (manufactured by DIC Corporation) was added as a solid content to the image forming layer coating solution of Example 3 as a photothermal conversion agent. Samples and comparative samples were made. Image exposure was performed with a semiconductor laser (wavelength 830 nm, output 500 mw) at a resolution of 1200 dpi, and the same print evaluation as in Example 3 was performed. As a result, the same print result as in Example 3 was obtained.

(Example 8)
A coating solution for the first layer (image forming layer (A)) as shown in Table 7 is applied to one side of a polyethylene-coated paper having a thickness of about 180 μm and laminated on both sides as shown in Table 7. Prepared, applied by a slide hopper coating method at a moisture application amount of 20 g / m ² , dried, and further coated with the second layer (image forming layer (C)) as shown in Table 7 in the image forming layer coating solution d formulation. A liquid is prepared, applied by a slide hopper coating method at a moisture application amount of 10 g / m ² , dried, and further, the third layer (image forming layer (B)) of the image forming layer coating liquid d formulation as shown in Table 7 A coating solution was prepared, applied at a moisture application amount of 10 g / m ² by a slide hopper coating method, and dried to prepare an image forming layer. 28-31 thermosensitive lithographic printing plates were obtained. For the compounds of general formulas (1) to (4), the developer, and the color former, in the same manner as in Example 3, individually using a small dynomill (bead mill) and using zirconia beads at a solid content concentration of 30% in advance. Each was finely dispersed and used in the form of a dispersion. For comparison, the sample No. Heat-sensitive lithographic printing plates 26 and 27 were used. The heat-sensitive lithographic printing plate produced in this way was evaluated in the same manner as in Example 3. The results are shown in Table 8.

As can be seen from the results shown in Table 8, even when three image forming layers were provided, the general formulas (1) to (4) for the water-soluble polymer compound in the image forming layer (A) close to the water-resistant support were used. By making the ratio of the compounds shown higher than that in the image forming layer (B) farthest from the water-resistant support, in addition to sufficient printing durability and stain resistance (water retention), It can be seen that a thermal lithographic printing plate with improved printing defects and image disturbance due to the sticking phenomenon can be obtained.

Example 9
Applying the following undercoat layer, image forming layer (A), and image forming layer (B) coating liquid to one side of approximately 180 μm thick polyethylene-coated paper that has been laminated on both sides by a slide hopper coating method. The undercoat layer coating solution a is 15 g / m ² , the image forming layer (A) coating solution e is 30 g / m ² , and the image forming layer (B) coating solution f is 10 g / m ² in coating amounts. Three layers were simultaneously applied so that an undercoat layer, an image forming layer (A), and an image forming layer (B) (uppermost layer) were formed in this order from the support side.

The undercoat layer coating solution a is obtained by adding titanium dioxide into water to which a dispersant has been added and subjecting the mixture to high-speed fine dispersion for 30 minutes using a homomixer, and then sequentially adding gelatin, surfactant, and divinyl sulfone. Prepared by mixing. A part of the undercoat layer coating solution a was collected and diluted, and the average particle size of titanium dioxide was measured using a laser scattering type particle size distribution meter (LA920 manufactured by Horiba, Ltd.). Met.

As the color former mixed slurry used in the image forming layer (A) coating solution e and the image forming layer (B) coating solution f, those prepared in advance by the following preparation method were used.
<Preparation of color former mixed slurry>
Material a: 1,2-bis (3-methylphenoxy) ethane (manufactured by Sanko Co., Ltd .: KS-232)
Material b: 4-hydroxy-4'-isopropoxydiphenyl sulfone (manufactured by Nippon Soda Co., Ltd .: D-8)
Material c: 3-dibutylamino-6-methyl-7-anilinofluorane (manufactured by Yamamoto Kasei Co., Ltd .: ODB2)

Each of the above materials a, b, and c is preliminarily dispersed in a small dyno mill (bead mill) using a zirconia bead to an arbitrary particle size to produce a dispersion liquid adjusted to a solid content concentration of about 30%. Dispersion a, dispersion b, and dispersion c were obtained. A color former mixed slurry was prepared by mixing 3 parts of dispersions a and b with 1 part of dispersion c at room temperature.

After three layers were simultaneously applied at the above moisture application amount, the coating film was immediately gelled with cold air at 3 ° C. and then dried with hot air at 30 ° C. After drying, by heating for 7 days using a constant temperature and humidity chamber adjusted to a temperature of 40 ° C./humidity of 40%, sample No. 32 heat-sensitive lithographic printing plates were obtained. The cross section of the obtained heat-sensitive lithographic printing plate was observed using a scanning electron microscope, and the average dry film thickness of the undercoat layer was determined from the average value at any 10 locations. The average dry film thickness of the image forming layer was about 5.0 μm for both the A layer and the B layer.

Sample No. Sample No. except that the titanium dioxide TISR1 contained in the undercoat layer coating liquid a used in the preparation of the 32 heat-sensitive lithographic printing plate was changed to TYPEKE R-580 (Ishihara Sangyo Co., Ltd., rutile type, alumina treatment). . In the same manner as the heat-sensitive lithographic printing plate No. 32, sample No. 33 heat-sensitive lithographic printing plates were obtained. At this time, the average dry film thickness of the undercoat layer was 1.5 μm, and the average particle diameter of titanium dioxide was 0.9 μm.

Sample No. The amount of titanium dioxide (Typaque R-580) contained in the undercoat layer coating solution a used in the preparation of the 33 heat-sensitive lithographic printing plate was changed from 4 parts to 3 parts, and the gelatin amount was further changed from 0.8 parts to 0 parts. Sample No. except for changing to 6 parts. In the same manner as in the heat-sensitive lithographic printing plate No. 33, sample No. 34 heat-sensitive lithographic printing plates were obtained. At this time, the average dry film thickness of the undercoat layer was 1.2 μm, and the average particle diameter of titanium dioxide was 0.9 μm.

Sample No. produced as described above. 32 to 34 thermosensitive lithographic printing plates were output using a thermal digital printer for CTP (Thermal Digiplater TDP-459: 1200 dpi / 120 lpi manufactured by Mitsubishi Paper Co., Ltd.) (recording energy density 70 to 100 mJ / mm ² , electric A capacity of 330 W) was performed to prepare a printing plate.

The printing plate produced in this way was mounted on an offset printing machine as it was and subjected to plate surface etching using the following moisturizing liquid, followed by printing.

The total volume was made up to 2 liters with water.

Printing was performed using an offset printing machine (manufactured by Heidelberg: QM46), Fusion G black N ink manufactured by DIC Corporation as the printing ink, and the above-described humidifying liquid as the humidifying liquid.

<Image quality evaluation>
The reproducibility of 1Q (class) fine line characters on the printed paper surface was observed with a 25-fold loupe and judged using the following evaluation criteria. The results are shown in Table 9.
○: There is no chipping in 1Q characters, and they are reproduced sharply.
Δ: Partially chipped in 1Q character, slightly sharpened.
×: Most of Q characters are missing.

<Print durability>
Printing was performed until the reproducibility of 1Q (class) fine line characters on the printing paper was lost, and the determination was made using the following evaluation criteria. The results are shown in Table 9.
○: More than 3,000 sheets △: Less than 2,000 to 3,000 sheets ×: Less than 2,000 sheets

<Bran scratch resistance>
Printing was performed by increasing the plate-blankette pressure to about 2 times during normal printing, observing the stain on the head edge and the bottom edge of the 500th printing paper surface, and judging using the following evaluation criteria. The results are shown in Table 9.
○: No local partial stains or non-uniform stains are observed.
(Triangle | delta): A local partial stain | pollution | contamination and nonuniform stain | pollution | contamination are slightly seen.
X: Local partial stains and non-uniform stains are clearly seen.

<Scratch resistance>
Using a HEIDON Scratching Intensity Tester: HEIDON-18 type, the obtained thermosensitive planographic printing plate was immersed in water at 23 ° C. for 60 seconds, and then evaluated under the conditions of a sapphire needle 0.2 mm and a scratching speed of 10 mm / sec. The determination was made based on the weighted value [g] in which the surface of the printing plate was damaged. The results are shown in Table 9.

As can be seen from the results shown in Table 9, between the image forming layer (A) close to the water-resistant support and the water-resistant support, titanium dioxide and a binder having an average particle size smaller than the average dry film thickness of the undercoat layer It can be seen that by providing an undercoat layer containing at least a resin and a crosslinking agent, a heat-sensitive lithographic printing plate having improved scratch resistance can be obtained without deteriorating image quality and printing durability.

(Example 10)
An undercoat layer coating solution b, an image forming layer (A) coating solution g, and an image forming layer (B) applied to one side of a polyethylene resin-coated paper having a thickness of about 180 μm and laminated on both sides. The coating solution h was simultaneously applied in triple layers by the slide hopper coating method so that the undercoat layer, the image forming layer (A), and the image forming layer (B) (uppermost layer) were arranged in this order from the support side. At that time, the wet coating weight, the undercoat layer coating solution b is 15 g / ^{m 2,} the image forming layer (A) coating liquid g of 30 g / ^{m 2,} the image forming layer (B) coating liquid h is 10 g / It was carried out set to m ^2.

In preparing the titanium dioxide slurry used for the undercoat layer coating solution b and the barium sulfate slurry used for the image forming layer (A) coating solution g, an acrylic acid copolymerized metal salt is used as a pigment dispersant. The production method is to gradually add titanium dioxide or barium sulfate under water with constant stirring to the water to which the pigment dispersant has been added, and perform high-speed fine dispersion treatment for 30 minutes using a homomixer. Can be made. The slurry used was prepared just before preparing the coating solution.

Moreover, the developer mixed slurry used for the image forming layer (A) coating solution g was prepared and manufactured in advance with the following constituent chemicals.
<Constituent chemicals of developer mixed slurry>
Material a: KS-232
(Sanko Co., Ltd., sensitizer, 1,2-bis (3-methylphenoxy) ethane)
Material b: D-8
(Nippon Soda Co., Ltd., developer, 4-hydroxy-4'-isopropoxydiphenyl sulfone)
Material c: Polymeron 1318
(Arakawa Chemical Co., Ltd., dispersant, 15% aqueous solution of anionic styrene resin)

After mixing 1 part each of material a and material b in water to which 0.7 part of the material c is added under constant stirring, any particle size can be obtained using zirconia beads in a small dyno mill (bead mill). Fine dispersion treatment was performed until a developer mixed slurry was obtained. In addition, it adjusted so that solid content concentration in the sum total of the material a, the material b, and the material c might be about 35%.

For other chemicals, no special adjustments were made except for water splitting, except that hydrophilic polymers such as gelatin, polyvinyl alcohol and water-soluble polysaccharides were heated and dissolved in water. However, with respect to the developer mixed slurry, care was taken from the stage of preparation and with respect to the color former, so that the temperature did not exceed 45 ° C. throughout the handling.

After three layers were simultaneously applied at the above moisture application amount, the coating was immediately gelled with cold air of 1 to 3 ° C., and then dried with hot air set at 30 ° C. After drying, by heating for 7 days using a constant temperature and humidity chamber adjusted to a temperature of 40 ° C./humidity of 40%, sample No. 35 heat-sensitive lithographic printing plates were obtained.

Sample No. Zinc oxide (manufactured by Sakai Chemical Industry Co., Ltd., fine zinc oxide, average particle size = 0) instead of barium sulfate contained in the image-forming layer (B) coating solution h used in the preparation of the 35 heat-sensitive lithographic printing plate Sample no. In the same manner as in the heat-sensitive lithographic printing plate No. 35, sample No. 36 heat-sensitive lithographic printing plates were obtained.

Sample No. Except that the addition amount of the barium sulfate slurry contained in the image forming layer (B) coating solution h used for the preparation of the thermosensitive lithographic printing plate No. 35 was changed from 0.03 part to 0.06 part, sample No. In the same manner as in the heat-sensitive lithographic printing plate No. 35, sample No. 37 thermosensitive lithographic printing plates were obtained.

Sample No. Except that the addition amount of the barium sulfate slurry contained in the image forming layer (B) coating solution h used for the preparation of the thermosensitive lithographic printing plate No. 35 was changed from 0.03 part to 0.08 part, sample No. In the same manner as in the heat-sensitive lithographic printing plate No. 35, sample No. 38 heat-sensitive lithographic printing plates were obtained.

Sample No. Except for changing the addition amount of the barium sulfate slurry contained in the image forming layer (B) coating liquid h used in the preparation of the thermosensitive lithographic printing plate No. 35 from 0.03 part to 0.0135 part, In the same manner as in the heat-sensitive lithographic printing plate No. 35, sample No. 39 thermosensitive lithographic printing plates were obtained.

Sample No. produced as described above. A thermal lithographic printing plate of 35 to 39 was subjected to image output (recording energy density 70 to 100 mJ / mm ² , electric power using a thermal digital printer for CTP (Thermal Digiplater TDP-459: 1200 dpi / 120 lpi manufactured by Mitsubishi Paper Co., Ltd.) A printing plate was prepared by performing a capacity of 330 W). Using this printing plate, printability was evaluated by the following method.

<Print durability>
The printing machine uses an offset sheet-fed press Heidelberg QM46, the printing ink is FusionG black N from Dainippon Ink & Chemicals, and the dampening solution is 10% diluted with SLM-OD from Mitsubishi Paper Industries. Printing was performed using the same moisturizing liquid as it was for the etching liquid. For printing durability evaluation, the printing paper surface at the start and the printing paper surface at the time of printing 5,000 sheets were compared, and the attenuation ratio of 20% halftone dot and 50% halftone dot was observed with a 25 times loupe. The evaluation criteria were used. The results are shown in Table 10.
◎: Almost no change in both 20% and 50% halftone dot portions ○: Almost no change in the 50% halftone dot portion, but attenuation can be confirmed in the 20% halftone dot portion △: Both the 20% and 50% halftone dot portions Attenuation can be confirmed ×: More than 50% attenuation is observed at 20% halftone dot part XX: Over 90% attenuation is observed at 20% halftone dot part

<Soil stain resistance (water retention)>
The offset press is also the Heidelberg QM46 offset sheet-fed press. The printing ink is FusionG Ink S from Dainippon Ink Chemical Co., Ltd., and the Astro Mark III from Nikken Chemical Co., Ltd. is used as the dampening solution. .5% diluted solution was used and printing was started without etching. As the background stain resistance evaluation, the following evaluation criteria were used on the 2,000th printed paper surface from the start of printing. The results are shown in Table 10.
◎: No scumming up to the 1st to 2,000th sheets ○: No scumming up to the 1st to 1500th sheets △: No scumming up to the 1st to 1000th sheets ×: Printing Smudge out (5 sheets or less), or less than 1,000 background xx: Print out stain (6 sheets or more)

As can be seen from the results shown in Table 10, when the image forming layer (B) farthest from the water-resistant support contains zinc oxide or barium sulfate, the printing durability and soil resistance (water retention) are improved. It can be seen that a heat-sensitive lithographic printing plate with improved balance is obtained.

Claims

An image forming layer (B) that has at least two image-forming layers containing a water-soluble polymer compound and a thermoplastic resin on a water-resistant support, and is furthest from the water-resistant support, and an image forming layer (B) A heat-sensitive lithographic printing plate that satisfies the following requirements i) and / or ii) with an image forming layer (A) closer to a water-resistant support.
i) The ratio of the thermoplastic resin to the water-soluble polymer compound in the image forming layer (A) is higher than the ratio of the thermoplastic resin to the water-soluble polymer compound in the image forming layer (B).
ii) The ratio of at least one compound selected from the compounds represented by the following general formulas (1) to (4) to the water-soluble polymer compound in the image forming layer (A) is the water solubility in the image forming layer (B). Higher than the ratio of at least one compound selected from the compounds represented by the following general formulas (1) to (4) to the functional polymer compound.

(Wherein X 1 represents —O— or —CO—O—,
R 1 , R 2 and R 3 each independently represent a hydrogen atom, an alkyl group or an aryl group, or R 1 , R 2 and R 3 are bonded to each other to form an aromatic ring;
R 4 , R 5 and R 6 each independently represent a hydrogen atom, an alkyl group or an aryl group, or R 4 , R 5 and R 6 are bonded to each other to form an aromatic ring;
n represents an integer of 1 to 10. )

(Wherein R 7 represents an alkyl group, an aryl group, an alkylcarbonyl group, an arylcarbonyl group, an alkylsulfonyl group or an arylsulfonyl group, and the naphthalene ring of the general formula (2) further has a substituent. May be.)

(Wherein R 8 and R 9 each independently represent a hydrogen atom, a halogen atom, an alkyl group having 1 to 4 carbon atoms or an alkoxy group having 1 to 4 carbon atoms, and X 2 represents a single bond or —O -Represents n, and n represents an integer of 1 to 4.)

(Wherein R 10 , R 10 ′ , R 11 and R 11 ′ each independently represents a hydrogen atom, a halogen atom, an alkyl group, an aryl group, an alkoxy group, an alkylcarbonyl group, an arylcarbonyl group or an alkoxycarbonyl group. Or an aryloxy group.)
The difference between the ratio of the thermoplastic resin to the water-soluble polymer compound in the image forming layer (A) and the ratio of the thermoplastic resin to the water-soluble polymer compound in the image forming layer (B) is 0.5 or more. The heat-sensitive lithographic printing plate according to claim 1.
The ratio of the thermoplastic resin to the water-soluble polymer compound in the image forming layer (A) is from 1 to 20, and the ratio of the thermoplastic resin to the water-soluble polymer compound in the image forming layer (B) is from 0.1 to The heat-sensitive lithographic printing plate according to claim 1, which is 3.
The ratio of at least one compound selected from the compounds represented by the general formulas (1) to (4) to the water-soluble polymer compound in the image forming layer (B) is 0.5 or less. The thermal lithographic printing plate as described.
The ratio of at least one compound selected from the compounds represented by formulas (1) to (4) to the water-soluble polymer compound in the image forming layer (A), and the water solubility in the image forming layer (B) The thermosensitive lithographic plate according to claim 1 or 4, wherein a difference from a ratio of at least one compound selected from the compounds represented by the general formulas (1) to (4) to the polymer compound is 1.0 or more. Print version.
The heat-sensitive lithographic printing plate according to any one of claims 1 to 5, which satisfies the requirements of i) and ii).
An undercoat layer containing at least titanium dioxide, a binder resin, and a crosslinking agent having an average particle size smaller than the average dry film thickness of the undercoat layer between the image forming layer (A) and the water-resistant support. The heat-sensitive lithographic printing plate according to any one of 1 to 6.
The heat-sensitive lithographic printing plate according to any one of claims 1 to 7, wherein the image forming layer (B) contains zinc oxide or barium sulfate.
The heat-sensitive lithographic plate according to any one of claims 1 to 8, wherein the image-forming layer contains 5 to 30% by mass of a hardener based on the solid content of the water-soluble polymer compound contained in the entire image-forming layer. Printed version.
A printing method for a heat-sensitive lithographic printing plate, wherein printing is performed without removing the image forming layer after printing on the heat-sensitive lithographic printing plate according to any one of claims 1 to 9.