JPH11291654A - Laser sensitive lithographic printing plate original plate and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a high ink repellency and excellent printing durability by sequentially providing an ink receiving layer, a heat sensitive layer and a hydrophilic swelling layer in this order on a base plate, forming the heat sensitive layer of a thin film of a carbon and/or metal of a specific film thickness, and forming the ink receiving layer of a specific compound. SOLUTION: To efficiently absorb a laser beam, a heat sensitive layer is formed of a thin film having a film thickness of 1,000 Angstrom or less made of a carbon and/or a metal. An ink receiving layer has rigid adhesive properties of the plate to the sensitive layer and carries a role of a thermal insulating layer. The receiving layer is made of a polymer compound obtained from a monomer having a hydroxyl group, carbonyl group, carboxyl group, isocyanate group, or epoxy group or a compound having a hydroxyl group, carbonyl group, carboxyl group, or epoxy group. Since the receiving layer contains a chemical bond having such an oxygen or a functional group having an oxygen, adhesive properties of the receiving layer to a hydrophilic swelling layer become rigid, and an ink repellency and printing durability are improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lithographic printing plate precursor, in which digitally processed image information can be drawn by using a laser in a plate making process, and a desensitizing process in a printing process. The present invention relates to a novel laser-sensitive lithographic printing plate precursor which has high ink repellency, has a wide control range of dampening solution, can be IPA-free without dampening solution, and has excellent printing durability without performing printing. .

[0002]

2. Description of the Related Art As a plate to be used for lithographic printing, a lipophilic photosensitive layer is applied on an aluminum substrate which has been subjected to a hydrophilic treatment, and the photosensitive layer remains on the image portion by a photolithography technique, while a non-image forming layer is formed. The line portion exposes the surface of the aluminum substrate and uses a dampening water layer on the surface to repel the ink, thereby using a PS plate with water to form an ink image and a silicone instead of the dampening solution. A waterless PS plate using a rubber layer as an ink repellent layer, a so-called waterless lithographic plate, is known.

[0003] The PS plate with water is a printing plate excellent in practical use. Usually, grained aluminum is used for the support, and a treatment such as anodizing the surface of the grain is performed as necessary. The improvement in the water retention of the dampening solution and the adhesion to the photosensitive layer are reinforced. The PS plate with water is widely used due to its excellent printing characteristics (printing durability, image reproducibility, etc.), while the PS plate with water has such a complicated manufacturing process and its simplification. Is desired. Therefore,
In order to solve this problem, there has been proposed a new lithographic material having printing characteristics equal to or better than that of an aluminum substrate, and having a low material cost and different from an aluminum substrate by a simple manufacturing process. For example, Japanese Patent Publication No. 56-2
No. 938 proposes a method of forming a photosensitive layer on a support by using a support provided with an ink repellent layer made of a hydrophilic polymer material instead of the aluminum substrate. However, since the lithographic printing plate is a simple coating of a urea resin as a hydrophilic layer on a water-resistant layer of an aldehyde condensate of polyvinyl chloride, polyurethane, or polyvinyl alcohol, the ink repellency is insufficient. In addition, the adhesion to the photosensitive layer was poor, and the printing durability was insufficient.

JP-A-5-19460 discloses a lithographic printing plate comprising an inorganic porous material such as polyvinyl alcohol, a crosslinking agent, and titanium oxide. This printing plate compensates for the lack of water retention of polyvinyl alcohol by containing a large amount of inorganic porous materials such as titanium oxide, but the ink itself is not necessarily good because the layer itself is hard and cannot substantially swell. Instead, the printing durability was poor.

[0005] As a simple form of the PS plate with water,
On a support such as paper, having an image receiving layer such as toner,
A direct-drawing lithographic printing plate precursor that forms an image using electrophotographic technology, desensitizes non-image areas with an etchant, etc., and converts the image receiving layer to an ink repellent layer for use is widely used. I have. Specifically, a water-resistant support is generally provided with an image-receiving layer comprising a water-soluble binder polymer, an inorganic pigment, a water-proofing agent, and the like, and is disclosed in US Pat. No. 2,532,865.
JP-B-40-23581, JP-A-48-9802
JP, JP-A-57-205196, JP-A-57-205196
JP-A-2309, JP-A-57-1791, JP-A-57-15998, JP-A-57-96900, JP-A-57-205196, JP-A-63-
JP-A-166590, JP-A-63-166593, JP-A-63-317388, JP-A-1-11
No. 4488, JP-A-4-366868, and the like. These direct-lithographic printing plate precursors are PVA, starch, hydroxyethylcellulose, casein, gelatin, polyvinylpyrrolidone, vinyl acetate-crotonic acid copolymer, as an image receiving layer to be converted into an ink repellent layer.
Water-soluble binder polymers such as styrene-maleic acid copolymer and the like, which are hydrophilic before being desensitized, water-dispersible polymers such as acrylic resin emulsions, inorganic pigments such as silica and calcium carbonate, and melamine -A material composed of a waterproofing agent such as a formaldehyde resin condensate has been proposed. In order to convert the image receiving layer into an ink repellent layer, the direct drawing type lithographic printing plate requires desensitization treatment, and shows no ink repellency without the treatment. Special agents had to be used as fountain solution.

[0006] Furthermore, the PS plate with water needs to constantly control the amount of dampening solution at the time of printing, and considerable skill and experience have been required to control the amount of dampening solution properly. IPA added as an essential component to the fountain solution
In recent years, the use of (isopropanol) has been strictly regulated from the standpoint of the occupational health environment and wastewater treatment, and countermeasures are urgently needed.

[0007] These PS plates are made into a printing plate through a plate making process by photolithography technology such as exposure and development through an original film, but in recent years, instead of using the original film, digital processing using a laser has been used as an alternative technology. There is proposed a laser-sensitive lithographic printing plate in which the image information obtained is drawn directly on the plate surface.

As a method for making a PS plate with water which requires dampening water a laser-sensitive type, many types have been proposed in which a direct drawing is performed using a high-sensitivity photopolymer which is sensitive to a He-Ne or Ar laser. However, the plate material cannot be handled in a bright room because of its high sensitivity, and a large-scale and expensive automatic exposure and development plate-making apparatus is required.

On the other hand, as a method for making a waterless planographic printing plate a laser-sensitive type, for example, DE-A 2512038
The image formation is performed using a laser using a heat mode recording material in which a layer containing nitrocellulose and carbon black and a non-cured silicone layer are laminated on a support having or having a lipophilic surface. After that, a method has been proposed in which the exposed portion of the silicone layer is dissolved using a solvent such as naphtha and the other portion of the silicone layer is cured. However, in this method, it is difficult to handle a plate material during plate making, a curing step of a silicone layer is required in a development step, and the use of an organic solvent is indispensable from the viewpoint of environmental problems. Was something.

[0010] In FR-A1473751,
A heat mode recording material using a layer having nitrocellulose, carbon black, and silicone on a substrate having a lipophilic surface has been proposed. After forming an image using a laser, the image forming portion becomes lipophilic. Is converted to However, this method has a poor ink-adhesive property because the silicone in the ink-impregnated portion is not removed from the plate surface.

In US Pat. No. 5,353,705,
There has been proposed a heat mode recording material in which polyvinyl alcohol is laminated as an ink repellent layer on a laser sensitive layer composed of nitrocellulose and carbon black. However, the ink repellency was extremely insufficient even under a dampening water supply.

[0012]

DISCLOSURE OF THE INVENTION The present inventors can directly draw image information digitally processed by using a laser on a printing plate, and control the dampening solution during printing more than the conventional PS plate with water. To provide a novel laser-sensitive lithographic printing plate precursor that has a wide width, is free of IPA without dampening solution, and has high ink repulsion without going through complicated plate-making processes such as desensitization treatment. Is the subject.

[0013]

In order to solve the above-mentioned problems, a laser-sensitive lithographic printing plate precursor according to the present invention has the following constitution.

(1) At least an ink receiving layer on a substrate,
A lithographic printing plate precursor comprising a heat-sensitive layer and a hydrophilic swelling layer provided in this order, wherein the heat-sensitive layer is a thin film of carbon and / or metal having a thickness of 1,000 Å or less, and the ink-receiving layer is a hydroxyl group, a carbonyl group, Carboxyl group,
A laser-sensitive lithographic printing plate precursor comprising a polymer compound obtained from a monomer having an isocyanate group and an epoxy group and / or a compound having a hydroxyl group, a carbonyl group, a carboxyl group and an epoxy group.

(2) The laser-sensitive lithographic printing plate precursor as described in (1), wherein the heat-sensitive layer is formed by forming a carbon thin film on a metal thin film.

(3) The melting point of the metal used for the heat-sensitive layer is 200
The laser-sensitive lithographic printing plate precursor according to any one of (1) to (2), which is 0 (K) or less.

(4) The metal is selected from the group consisting of titanium, aluminum, nickel, iron, chromium, tellurium, tin, antimony, gallium, magnesium, polonium, selenium, thallium, zinc and bismuth.
The lithographic printing plate precursor according to (3), wherein at least one kind of metal is used.

(5) The method for producing a laser-sensitive lithographic printing plate precursor as described in any one of (1) to (4), wherein the heating is performed at a temperature of 100 ° C. or more after providing the heat-sensitive layer.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The construction of a laser-sensitive lithographic printing plate precursor according to the present invention will be described.

The laser-sensitive lithographic printing plate precursor of the present invention is obtained by laminating at least an ink-receiving layer, a heat-sensitive layer, and a hydrophilic swelling layer on a substrate.

First, the heat-sensitive layer will be described.

The heat-sensitive layer of the present invention comprises a thin film made of carbon and / or metal. The thickness of the heat-sensitive layer is 10
It is preferably not more than 00 angstroms, more preferably not more than 700 angstroms.

If the film thickness is more than 1000 angstroms, the sensitivity to laser is undesirably reduced.

The optical density of the heat-sensitive layer is 0.6-2.
It is preferably 3. However, the optical density referred to here is the Ratten filter No. 106 refers to a numerical value when measured by a Macbeth densitometer RD-514.

It is important that the heat-sensitive layer of the present invention efficiently absorbs a laser beam and instantaneously evaporates or melts a part or all of the heat by the heat.

In order to efficiently absorb laser light,
The wavelength of a semiconductor laser used as a light source (80
(Near 0 nm) becomes important. The optical density of the heat-sensitive layer is important as an index of the absorptivity for light near 800 nm, and the higher the optical density, the more efficiently the laser light can be absorbed.

The optical density is preferably from 0.6 to 2.3, and more preferably from 0.8 to 1.8. When the optical density is lower than 0.6, the sensitivity of the printing plate is apt to decrease because the laser light is not efficiently absorbed, and when the optical density is higher than 2.3, the film thickness is too thick and the energy required to form an image. Is required, and the sensitivity is reduced.

In order to realize a higher optical density, it is preferable to vapor-deposit or sputter carbon and metal simultaneously or to laminate a carbon thin film and a metal thin film.
In laminating a carbon thin film and a metal thin film, it is preferable to form a carbon thin film after forming a metal thin film from the viewpoint of sensitivity.

The carbon thin film is preferably not a so-called diamond thin film or graphite thin film but an amorphous carbon thin film.

Such an amorphous carbon thin film can be obtained by performing ordinary vacuum evaporation such as ion beam evaporation or ionization evaporation or ion beam sputtering. At this time, a diamond thin film or a graphite thin film is hardly formed. The thin films formed by these methods are amorphous carbon thin films.

The metal used for the heat-sensitive layer is not particularly limited as long as it can be deposited or sputtered and can form a thin film, but preferably has a melting point of 2000 (K) or less, more preferably 1000 (K) or less.

If the melting point is higher than 2,000 (K), not only extra energy is required for vapor deposition or sputtering, but also extra energy is required at the time of forming an image with a laser, which is not preferable.

Specifically, preferred metals include titanium, aluminum, nickel, iron, tellurium, tin, antimony, gallium, magnesium, polonium, selenium, thallium, zinc, bismuth and the like. Antimony, gallium, bismuth, and zinc are more preferred. These metals are easily evaporated or melted by heat when the thin film is irradiated with laser light.

However, on the contrary, even if the melting point is too low, the shape retention of the printing plate is apt to be deteriorated. Therefore, a particularly preferable temperature range is 500 (K) to 1000 (K).

By using two or more of the above metals to form an alloy, the melting point can be further reduced and the sensitivity as a printing plate can be increased.

Specifically, alloys of tellurium and tin, tellurium and antimony, tellurium and gallium, tellurium and bismuth, tellurium and zinc are preferred, and more preferred are tellurium and zinc, and tellurium and tin.

Of the three alloys, alloys of tellurium, tin and zinc, tellurium, gallium and zinc, tin, antimony and zinc, tin, bismuth and zinc are preferred, and more preferably tellurium, tin and zinc, and tin. Bismuth and zinc.

When a metal and carbon are simultaneously deposited or sputtered, the weight percent of carbon in the formed thin film is preferably 10% by weight or more, more preferably 30% by weight.
That is all. If the amount of carbon is less than 10% by weight, the absorptivity of laser light is reduced, and the sensitivity of the printing plate is likely to be reduced.

When a carbon thin film and a metal thin film are laminated, the film thickness ratio between the two is also important because it affects the sensitivity of the printing plate. Specifically, when the thickness of the metal thin film is 1, the thickness of the carbon thin film is preferably 1/4 to 6.
When the thickness ratio of the carbon film thickness is smaller than 1/4, the effect of improving the sensitivity is not obtained, and when it is larger than 6, it becomes difficult to form a carbon thin film.

Further, whether the layer is a single layer of carbon or metal (alloy) or a layer of carbon and metal (alloy), the thickness of the thin film of the entire heat-sensitive layer has a great influence on the sensitivity. give. That is, if the film thickness is too thick, extra energy is required to evaporate and melt the thin film, so that the sensitivity of the printing plate is reduced. Therefore, the thickness of the heat-sensitive layer is preferably 1,000 Å or less, more preferably 200 Å or less.

As a method for forming such a thin film, it is preferable to carry out any one of vacuum deposition and sputtering.

The vacuum evaporation is generally performed by heating and evaporating metal and / or carbon in a vacuum vessel of 10 ⁻² to 10 ⁻⁷ mmHg to form a thin film on the surface to be formed. .

The sputtering is performed at 10 ^-1 to 10 ^-3 mmH
By applying a DC or AC voltage to a pair of electrodes in a reduced pressure container of g, a glow discharge is caused, and a thin film can be formed by utilizing a sputtering phenomenon of a cathode.

According to this method, a thin film can be formed relatively easily even with a metal or carbon having a high melting point.

The ink receiving layer of the present invention will be described.

The ink receiving layer of the present invention is preferably provided between the substrate and the heat-sensitive layer. Provided between the substrate and the heat-sensitive layer in order to strengthen the adhesiveness between the substrate and the heat-sensitive layer and to serve as a heat-insulating layer when the substrate uses a material with high thermal conductivity such as metal. Is preferred. That is, it plays a role of a thermal insulating layer for preventing heat generated by the heat-sensitive layer from diffusing into the substrate.

The ink receiving layer of the present invention contains a polymer compound obtained from a monomer having a hydroxyl group, a carbonyl group, a carboxyl group, an isocyanate group or an epoxy group, or a hydroxyl group, a carbonyl group, a carboxyl group or an epoxy group. It is preferable to contain a compound having a group from the viewpoint of developing strong adhesion between the ink receiving layer and the hydrophilic swelling layer. Since the ink receiving layer has the oxygen-containing chemical bond and the oxygen-containing functional group as described above, the adhesiveness between the ink receiving layer and the hydrophilic swelling layer, which is the upper layer, becomes particularly strong, and the printing durability is improved. The performance is improved. Although the mechanism is not always clear, when examining the interaction between the metal used in the thermosensitive layer and these chemical bonds and functional groups, it is found that the metal and the polar group (hydroxyl group, carbonyl group, carboxyl group, epoxy group) or the polar group The effect of chemical bonding is large, and the use of a compound having a highly polar part in the ink receiving layer increases the binding energy of the metal element in the heat-sensitive layer, and the charge from the metal to these polar groups and the chemical bonds derived from the polar groups. It is presumed that the adhesion between the ink receiving layer and the heat-sensitive layer becomes strong because a kind of complex is formed by the movement. Alternatively, at the time of vapor deposition, for example, O atoms are knocked out from a compound constituting the ink receiving layer, and a metal oxide is generated from the metal, and the metal atom is deposited on the metal oxide. It is presumed that strong adhesion is exhibited by bridging the bonding of the metal layers. Therefore, hydroxyl groups, carbonyl groups, carboxyl groups, which are functional groups containing oxygen,
It is very important to use an isocyanate group, an epoxy group itself or a compound having a chemical bond containing oxygen derived from these functional groups for the ink receiving layer from the viewpoint of adhesion to the heat-sensitive layer which is the upper layer of the ink receiving layer.

For the purpose of improving the adhesion between the ink receiving layer and the thermosensitive layer, it is preferable to provide a step of heating at a temperature of 100 ° C. or more after the thermosensitive layer is provided. It is more preferable that the heating temperature be 120 ° C. or higher.

As the binder resin for the ink receiving layer of the present invention, known resins can be used. Examples include cellulose, cellulose acetate, nitrocellulose, polyvinyl alcohol, polyvinyl pyrrolidone, polyvinyl butyral resin, acrylic resin, polyurethane resin, polyester resin, polyamide resin, cellulose acetate butyrate resin, ethylene vinyl acetate resin, and the like.

The ink receiving layer using the above materials may contain a laser beam absorbent for the purpose of absorbing laser energy.

In addition to these materials, a plasticizer, a wetting agent, a matting agent, an antioxidant and the like can be added to the ink receiving layer of the present invention. In addition, a known crosslinking agent can be added.

The compounds used for the crosslinking reaction include:
Known polyfunctional compounds having crosslinking properties include polyepoxy compounds, polyisocyanate compounds, poly (meth) acrylic compounds, polymercapto compounds, polyalkoxysilyl compounds, polyvalent metal salt compounds, polyamine compounds, aldehyde compounds, Examples thereof include a polyvinyl compound and an organic titanate. The crosslinking reaction may use a known catalyst to accelerate the reaction.

As the compound used for the crosslinking reaction, a compound having a hydroxyl group, a carbonyl group, a carboxyl group, an isocyanate group, or an epoxy group per se, or a compound capable of forming a chemical bond containing an oxygen atom by a crosslinking reaction, It can be preferably used as a component constituting the ink receiving layer together with the above resin component.

The thickness of the ink receiving layer is 0.1 to 20 g /
m ² is preferred, and 0.3 to 10 g / m ² is more preferred. When the film thickness is less than 0.1 g / m ² , the printing durability of the ink receiving layer decreases, and when the film thickness is more than 20 g / m ² , it is economically disadvantageous.

The ink receiving layer may be provided with a primer layer for the purpose of strengthening the adhesion between the substrate and the ink receiving layer, improving the ink adhesion, and preventing halation.

As the primer layer used in the present invention,
For example, in addition to those containing an epoxy resin as shown in JP-B-61-54219, polyurethane resins, phenol resins, acrylic resins, alkyd resins, polyester resins, polyamide resins, melamine resins, urea resins, benzoguanamine resins, Vinyl chloride-vinyl acetate copolymer, vinyl chloride resin, polyvinyl butyral resin,
Examples thereof include an ethylene-vinyl acetate copolymer, a polycarbonate resin, a polyacrylonitrile-butadiene copolymer, a polyether resin, a polyether sulfone resin, milk casein, and gelatin. These resins can be used alone or in combination of two or more.

Among these, it is preferable to use a polyurethane resin, a polyester resin, an acrylic resin, an epoxy resin, a urea resin, or the like alone or as a mixture of two or more.

As the anchor agent constituting the primer layer, a known adhesive such as a silane coupling agent can be used, and an organic titanate is also effective. Further, it is optional to add a surfactant for the purpose of improving coatability.

The composition for forming the above primer layer is prepared as a composition solution by dissolving in a suitable organic solvent such as DMF, methyl ethyl ketone, methyl isobutyl ketone, dioxane and the like. A primer layer is formed by uniformly applying the composition solution on a substrate and heating it at a required temperature for a required time.

The thickness of the primer layer is 0.5 to 50 g / m
² is preferred, and more preferably 1 to 10 g / m ² . When the thickness is less than 0.5 g / m ² , the effect of blocking morphological defects and chemical adverse effects on the substrate surface is low, and the thickness is 50 g / m ^2.
If the thickness is larger than m ^2, it is disadvantageous from an economic viewpoint, so the above range is preferable.

Next, the hydrophilic swelling layer will be described.

The term “hydrophilic” as used in the present invention means the property of being substantially insoluble in water and exhibiting water swelling property. A known hydrophilic polymer is laminated on a substrate by coating or transfer, and the like. A hydrophilic swelling layer which is cross-linked or pseudo-cross-linked using the method described above and insolubilized in water to make it water-swellable is used.

As used herein, the term “hydrophilic polymer” means a known water-soluble polymer (which means completely soluble in water) or a pseudo-water-soluble polymer (which means amphipathic, and macro-soluble in water. Micro means those containing undissolved parts),
Refers to water-swellable polymers (meaning those that swell in water but do not dissolve). That is, it refers to a polymer that adsorbs or absorbs water under normal use conditions, and a polymer that dissolves in or swells in water.

In the present invention, known hydrophilic polymers can be used, and examples thereof include animal polymers, plant polymers, and synthetic polymers. For example, "Function
nal Monomers "(by Y. Nyquist,
Dekker), "Water-soluble polymer" (by Nakamura, Chemical Industry Co., Ltd.), "Latest processing and modification technology of water-soluble polymer water-dispersible resin and application development Comprehensive technical materials" (Management Development Center Publishing Department) Water-soluble polymers described in "Applications and Markets of New Water-Soluble Polymers" (CMC). Specific examples are shown below.

(A) Natural polymers.

Starch-acrylonitrile-based graft polymer hydrolyzate, starch-acrylic acid-based graft polymer, starch-styrene sulfonic acid-based graft polymer, starch-vinyl sulfonic acid-based graft polymer,
Starch-acrylamide-based graft polymer, carboxylated methylcellulose, methylcellulose, hydroxypropylmethylcellulose, hydroxyethylcellulose, cellulose xanthate, cellulose-acrylonitrile-based graft polymer, cellulose-styrenesulfonic acid-based graft polymer, carboxymethylcellulose-based crosslinked product, hyaluronic Acid, agarose, collagen, milk casein, acid casein, rennet casein, ammonia casein, calicasein, borax casein, glue, gelatin, gluten, soy protein, alginate, ammonium alginate, potassium alginate, sodium alginate gum arabic, Tragacanth gum, karaya gum, guar gum, locust bean gum, Irish moss, large Lecithin, pectin acid, starch, carboxylated starch, agar, dextrin, mannan, etc..

(B) Synthetic polymers.

Polyvinyl alcohol, polyethylene oxide, poly (ethylene oxide-co-propylene oxide), aqueous urethane resin, water-soluble polyester, hydroxyethyl (meth) acrylate polymer, poly (vinyl methyl ether-co-maleic anhydride), Maleic anhydride copolymer, vinylpyrrolidone copolymer, polyethylene glycol di (meth) acrylate crosslinked polymer, polypropylene glycol di (meth) acrylate crosslinked polymer, poly (N-vinylcarboxylic amide), N -Vinyl carboxylic acid amide copolymers, etc.

The above-mentioned hydrophilic polymer may contain one or two monomers or copolymer components having different substituents for the purpose of imparting flexibility or controlling hydrophilicity, as long as the effects of the present invention are not impaired. It is possible to mix and use more than one kind as appropriate.

Specific examples of the hydrophilic polymer preferably used in the present invention are shown below, but the present invention is not limited to these examples.

(1) maleic acid or maleic anhydride,
Maleic acid derivatives such as maleic amide or maleic imide and ethylene, propylene, butylene, isobutylene or diisobutylene having 2 to 12 carbon atoms;
Preferably, a crosslinked product of a reaction product of a copolymer with a linear or branched α-olefin having 2 to 8 carbon atoms and an alkali metal compound, an alkaline earth metal compound, ammonia, or an amine.

(2) A copolymer of maleic acid or a derivative thereof with a vinyl or vinylidene compound such as styrene, vinyl acetate, methyl vinyl ether, acrylate, methacrylate or acrylonitrile, and an alkali metal compound or an alkaline earth metal Crosslinked product of reaction product with compound, ammonia and amine.

(3) A crosslinked product of a reaction product of a copolymer of acrylic acid or methacrylic acid with the vinyl or vinylidene compound of the above (2) and an alkali metal compound, an alkaline earth metal compound, ammonia and an amine.

A polyoxyalkylene hydrophilic polymer disclosed in JP-B-58-37027 and the like, polyvinylpyrrolidone disclosed in JP-A-60-104106 and the like, and a sulfonic acid group as a hydrophilic group Crosslinked products such as polystyrenesulfonic acid and acrylamidomethylpropanesulfonic acid copolymer
Polyurethane resins obtained by crosslinking a hydrophilic polymer having a hydroxyl group or an amino group with a polyisocyanate, which are disclosed in Japanese Patent No. 42416, and the like.

Next, a method for crosslinking a hydrophilic polymer will be described.

The hydrophilic swelling layer is formed on the substrate by cross-linking or pseudo-cross-linking at least one of the above-mentioned hydrophilic polymers as necessary, and insolubilizing in water. Crosslinking is performed by performing a crosslinking reaction using a reactive functional group of the hydrophilic polymer.

The crosslinking reaction may be covalent crosslinking or ionic crosslinking.

Examples of the compound used for the crosslinking reaction include known polyfunctional compounds having crosslinking properties, such as polyepoxy compounds, polyisocyanate compounds, poly (meth) acrylic compounds, polymercapto compounds, polyalkoxysilane compounds, and the like. Examples thereof include a polyvalent metal salt compound, a polyamine compound, an aldehyde compound, and a polyvinyl compound. The crosslinking reaction is carried out by adding a known catalyst to accelerate the reaction.

These hydrophilic polymers may be used alone or for the purpose of maintaining the form of the hydrophilic swelling layer and adjusting the water swelling property.
It can be used as a mixture of more than one species, and it is also possible to blend hydrophobic polymers.

The hydrophilic swelling layer of the present invention may contain a hydrophobic polymer. As such a hydrophobic polymer, those mainly composed of an aqueous emulsion are preferably used.

The aqueous emulsion referred to in the present invention means an aqueous solution of a hydrophobic polymer suspension in which particles comprising fine polymer particles and, if necessary, a protective layer surrounding the particles are dispersed in water.

That is, it means a self-emulsifying or forced emulsifying aqueous solution basically consisting of emulsion particles comprising polymer particles as a dispersoid, a protective layer formed as required, and a dilute aqueous solution as a dispersion medium. Specific examples of the aqueous emulsion used in the present invention include a vinyl polymer latex, a conjugated diene polymer latex, and an aqueous or water-dispersed polyurethane resin.

Among these aqueous emulsions, the hydrophobic polymers particularly preferably used in the present invention include styrene / butadiene type, acrylonitrile / butadiene type and
Latexes containing conjugated diene compounds such as methyl methacrylate / butadiene and chloroprene are mentioned.

The hydrophilic swelling layer of the present invention is formed on a substrate by mixing the above hydrophilic polymer and hydrophobic polymer, and cross-linking or pseudo-cross-linking as necessary, and insolubilizing in water.

For the crosslinking, it is preferable to carry out a crosslinking reaction using the reactive functional groups of the hydrophilic polymer and the hydrophobic polymer.

The crosslinking reaction may be covalent crosslinking or ionic crosslinking.

As a method of mixing the hydrophilic polymer and the hydrophobic polymer of the hydrophilic swelling layer of the present invention, a kneading method using a mixer such as a roll mixer such as a three-roller, a kneader, a homogenizer, a ball mill, etc. The mixing is preferably carried out by a known method used for producing a paint or putty, such as a method of wet mixing and dispersing using a disperser.

As a method for forming the hydrophilic swelling layer of the present invention, since an aqueous emulsion is preferably used as the hydrophobic polymer, each component (hydrophilic polymer, hydrophobic polymer, etc.) is mixed in an aqueous solution system, A method in which a crosslinking agent is added as necessary is preferable from the viewpoint of realizing a homogeneous phase separation structure and improving ink repulsion.

Therefore, it is particularly preferable to use a water-soluble polyfunctional compound as the crosslinking agent. That is, it is preferable to use a water-soluble polyepoxy compound, polyamine compound, melamine compound, or the like.

For the purpose of improving the adhesion to the lower layer, it is also possible to add a known silane coupling agent, isocyanate compound, catalyst or the like or to provide an intermediate layer.

The hydrophilic swelling layer used in the present invention preferably has a specific range of water absorption calculated according to the following method.

Water absorption (g / m ² ) = W _WET −W _DRY W _DRY : Weight in dry state (g / m ² ) W _WET : Weight after immersion in water at 25 ° C. × 10 minutes (g)
/ M ² ) [Method of measuring water absorption] A non-image area of a lithographic printing plate to be measured is cut into a predetermined area and immersed in purified water at 25 ° C. After immersion for 10 minutes, the excess liquid adhering to the hydrophilic swelling layer surface and the back surface of the printing plate was washed with "Hize gauze"
(Cotton cloth: manufactured by Asahi Kasei Kogyo Co., Ltd.), and the swelling weight W _WET of the printing plate is weighed. Thereafter, the printing plate is dried in an oven at 60 ° C. for about 30 minutes, and the dry weight W _DRY is weighed.

The water absorption of the non-image area composed of the hydrophilic swelling layer of the present invention is 1 from the viewpoint of ink repulsion and form retention.
５０50 g / m ² , preferably 1-10 g / m ^2
2 , more preferably ² to 7 g / m ² .

The hydrophilic swelling layer of the present invention preferably has rubber elasticity. That is, the initial elastic modulus of the hydrophilic swelling layer calculated by the following method is preferably within a specific range.

[Measurement Method of Initial Elastic Modulus] A solution having the same composition as the portion corresponding to the non-image area of the lithographic printing plate is spread on a Teflon dish and dried and cured at 60 ° C. for 24 hours. The obtained dried and cured film is 40 m long using a razor blade or the like.
The test piece is cut into a rectangular test piece having a width of 1.95 mm and a thickness of about 0.2 mm.

The obtained test piece was heated at 25 ° C. before measurement.
After standing for 24 hours or more in an environment of × 50% RH and adjusting the humidity, the thickness was measured with a micro gauge, and the initial elastic modulus was measured under the following tensile conditions. Data processing is JIS K
Performed according to 6301.

Tensile speed 200 mm / min Distance between chucks 20 mm Number of repetitions 4 times Measuring machine “RTM-100” (manufactured by Orientec Co., Ltd.) The initial elastic modulus of the hydrophilic swelling layer is 0.01 to 10 kgf /.
mm ² is important from the viewpoint of ink repulsion and form retention, and is 0.01 to 5 kgf / mm.
² is preferable, and the range of 0.01 to ² kgf / mm ² is more preferable. Initial elastic modulus is 0.01kgf / mm
If less than ^2, the shape retention of the hydrophilic swelling layer is reduced,
Poor durability during printing, initial elastic modulus 10 kgf / mm
^When it is larger than ² , the ink repellency is extremely reduced.

The hydrophilic swelling layer used in the present invention preferably has a water swelling ratio calculated according to the following method in a specific range.

Water swelling rate (%) = (Θ _WET -Θ _DRY ) / Θ _DRY × 100 Θ _DRY : Thickness (μm) of hydrophilic swelling layer consisting of non-image area in dry state Θ _WET : Non-swelling state in non-swelling state Thickness (μm) of hydrophilic swelling layer composed of image area [Method of measuring water swelling rate (A)] Cut and slice so that a portion including a non-image area of a lithographic printing plate to be measured has a cross section. Is prepared. After vacuum-drying this section at room temperature for one day and night, the thickness of the hydrophilic swelling layer at the site is observed with an optical microscope, and this is defined as _ΘDRY (μm). The observation with an optical microscope was performed quickly in an environment of 23 ° C. and 20% RH.

Further, an excess water droplet was placed on the lithographic printing plate section, the cross section was observed with an optical microscope in a state where the hydrophilic swelling layer was sufficiently swollen with water, and the thickness of the hydrophilic swelling layer at the site was read.と_する_WET (μm).

[Measurement method of water swelling ratio (B)] The non-image area of the lithographic printing plate to be measured was exposed to an OsO ₄ aqueous solution for one day and night to fix the hydrophilic swelling layer with OsO ₄ . An ultrathin section is prepared by cutting with a microtome so that a predetermined portion has a cross section. The thickness of the hydrophilic swelling layer at the site is observed with a transmission electron microscope (TEM) at a magnification of about 10,000 to 50,000 times, and this is defined as Θ _DRY (μm).

On the other hand, the planographic printing plate to be measured is
It is immersed in an O ₄ aqueous solution for 2 to 3 days to solidify / fix the hydrophilic swelling layer in a water swelling state. An ultra-thin section is prepared by cutting with a microtome so that a predetermined portion has a cross section, and the thickness of the hydrophilic swelling layer of the portion is determined by a transmission electron microscope (TEM) at a magnification of about 10,000 to 50,000 times. And read this,
_WET (μm).

The water swelling ratio of the non-image area (ink repelling portion) composed of the hydrophilic swelling layer of the present invention is preferably from 10 to 2,000% from the viewpoint of ink repellency and form retention, and is preferably from 50 to 1700. %, More preferably in the range of 50 to 700%. When the water swelling ratio is less than 10%, the ink resilience of the non-image portion decreases, while when the water swelling ratio of the non-image portion exceeds 2000%, the non-image portion has poor shape retention and printing. Sometimes, the non-image area is easily damaged.

In the hydrophilic swelling layer used in the present invention, in addition to the above-mentioned hydrophilic polymer, hydrophobic polymer and optionally a crosslinking agent, a known antioxidant usually added in a rubber composition. , An antioxidant, an antiozonant, an ultraviolet absorber, a dye, a pigment, a plasticizer, and the like.

For the purpose of improving the adhesiveness to the lower layer,
Known silane coupling agents and isocyanate compounds,
It is also possible to add a catalyst or the like or to provide an intermediate layer between the substrate and the substrate.

The hydrophilic swelling layer used in the present invention may contain trace amounts of various additives such as dyes and pigments, pH indicators, leuco dyes, surfactants and organic acids.

The substrate of the lithographic printing plate used in the present invention is not limited at all, except that it is required to have flexibility that can be attached to an ordinary lithographic printing machine and to withstand the load applied during printing.

Typical examples are aluminum, copper, iron,
And a plastic film such as a polyester film and a polypropylene film, or coated paper and a rubber sheet. Further, the substrate may be a composite of the above materials.

The surface of the substrate may be subjected to various surface treatments such as an electrochemical treatment, an acid-base treatment, and a corona discharge treatment for the purpose of improving plate inspection and adhesion.

It is also possible to form a primer layer on such a substrate by applying a coating or the like for the purpose of improving adhesiveness or preventing halation, thereby forming a substrate.

The plate making method of the laser-sensitive lithographic printing plate precursor according to the present invention will be described.

In the present invention, the laser sensitivity means that an image can be formed in a heat mode. That is, the laser-sensitive layer and the hydrophilic swelling layer in the portion corresponding to the laser irradiation instantaneously cause destructive absorption such as combustion and / or evaporation to form an ink-filled concave portion. The printing plate can be obtained only by performing the laser drawing process, but may be further washed with tap water or the like.

The laser preferably used in the present invention includes a semiconductor laser, an Nd-YAG laser, an argon laser, a helium-neon laser, a helium-cadmium laser, a carbon dioxide laser, and the like. For example, a semiconductor laser is preferable. Power output is 40-50
A power output of 000 mW is preferably used.
Among them, from the viewpoint that heat mode recording is performed efficiently, 5
A semiconductor laser of 00 to 30,000 mW is preferably used.

Usually, the diameter of the ink-filled concave portion formed by one laser irradiation is about 3 to 100 μm.

Next, a printing method using a printing plate obtained from the laser-sensitive planographic printing plate precursor of the invention will be described.

For the lithographic printing of the present invention, a known lithographic printing machine is used. That is, sheet-fed and rotary printing machines of the offset and direct printing type are used.

After the lithographic printing plate precursor of the present invention has been subjected to laser image formation, it is mounted on the plate cylinder of these lithographic printing presses,
Ink is supplied to the plate surface from an inking roller that comes into contact with the plate surface.

The non-image portion having the hydrophilic swelling layer on the plate swells with the dampening solution supplied from the dampening solution supply device and repels the ink. On the other hand, the image portion receives ink and supplies the ink to the surface of the offset blanket cylinder or the surface of the printing medium to form a printed image.

Hereinafter, the present invention will be described in more detail with reference to examples.

[0120]

EXAMPLES Synthesis Example 1 A mixture of 60 g of vinyl acetate and 40 g of acrylic acid to which 0.5 g of benzoyl peroxide was added as a polymerization initiator was added to 300 ml of water containing 3 g of partially saponified polyvinyl alcohol and 10 g of NaCl as a dispersion stabilizer. Was dispersed.

The dispersion was stirred at 65 ° C. for 6 hours to carry out suspension polymerization. The methyl acrylate component of the obtained copolymer was identified from the NMR spectrum to be 48 mol%. The intrinsic viscosity in a benzene solution at 30 ° C. was 2.10.

Next, 8.6 g of the copolymer was added to a saponification reaction solution comprising 200 g of methanol, 10 g of water and 40 ml of 5N NaOH, and the mixture was stirred and suspended.
After performing the saponification reaction for 1 hour, the temperature was raised to 65 ° C., and the saponification reaction was further performed for 5 hours.

The obtained saponification reaction product was sufficiently washed with methanol and freeze-dried. The saponification degree was 98.3 mol%, and as a result of measurement of an infrared absorption spectrum, 1570 cm
^{At -1} , strong absorption attributed to the -COO ^- group was confirmed.

Examples 1 to 5 The following composition was applied to an aluminum plate having a thickness of 0.2 mm (manufactured by Sumitomo Light Metal Co., Ltd.) and then cured by heating at 140 ° C. for 5 minutes to give a thickness of ² g / m ² . Was provided.

<Ink receiving layer composition (parts by weight)> (1) 20 parts by weight of polyester resin "Vylon-200: manufactured by Toyobo Co., Ltd." (2) Melamine resin "Sumimar M-40S: manufactured by Sumitomo Chemical Co., Ltd." 10 parts by weight (3) 40 parts by weight of toluene (4) 10 parts by weight of methyl ethyl ketone (5) 30 parts by weight of butyl acetate (6) 50 parts by weight of cyclohexanone Next, the metal compounds shown in Table 1 were vacuum-coated on the ink receiving layer. It was formed by a vapor deposition method, and a heat-sensitive layer was provided. After that, 18
Heat treatment was performed at 0 ° C. × 5 minutes.

[0126]

[Table 1] Further, the following composition was applied using the hydrophilic polymer described in Synthesis Example 1, and then heat-treated at 150 ° C. for 60 minutes to obtain a second composition.
A hydrophilic swelling layer having a thickness of g / m ² was applied.

<Composition of hydrophilic swelling layer (parts by weight)> (1) 28 parts by weight of hydrophilic polymer of Synthesis Example 1 (2) 5 parts by weight of tetraethylene glycol diglycidyl ether (3) 65 parts by weight of aqueous latex "JSR0596" [Carboxy-modified styrene-butadiene copolymer latex: manufactured by Dainippon Ink and Chemicals, Inc.] (4) 2-aminopropyltrimethoxysilane 2 parts by weight (5) Purified water 900 parts by weight The obtained laser-sensitive lithographic printing plate Using a semiconductor laser (SLD-304XT, output 1 W, wavelength 809 nm, manufactured by Sony Corporation) with the original mounted on an XY table,
Pulse exposure was performed with a beam diameter of 20 μm and an exposure time of 10 μs.

Subsequently, the plate was washed with tap water for about 1 minute to obtain a printing plate.

The laser heat-sensitive layer and the hydrophilic swelling layer in the portion corresponding to the laser irradiation were destroyed by burning, and the ink receiving layer having the spot diameter corresponding to the beam diameter was exposed.

This lithographic printing plate was mounted on a plate cylinder of a lithographic printing machine, and printing was performed by supplying ink from an ink-applying roller in contact with the plate surface and simultaneously supplying water from a dampening solution supply device. As a result, the ink-receiving layer exposed portion (image portion) received the ink, and a clear ink pixel corresponding to the beam diameter was formed on the printed matter via the offset blanket cylinder.

On the other hand, the hydrophilic swelling layer was swollen by the fountain solution, and a printed matter having the same contrast as that of the PS plate completely repelling the ink was obtained. Even after printing was completed for 5000 sheets, the hydrophilic swelling layer retained the ink repellency, and no ink stains occurred on the printed matter.

Comparative Example 1 A lithographic printing plate was produced in the same manner as in Example 1 except that a molybdenum thin film of 1200 Å was provided as a heat-sensitive layer. However, the heat-sensitive layer did not sufficiently burn in the laser-irradiated portion, the hydrophilic swelling layer remained, and no ink-filled portion was formed.

Example 6 A printing plate was obtained in the same manner as in Example 1, except that a carbon thin film of 60 Å was provided as a heat-sensitive layer by a sputtering method. In print evaluation, printing was 5000
Even after finishing the sheet, the hydrophilic swelling layer retains the ink repulsion,
No ink stains occurred on the printed matter. Also, the degree of ink deposition on the image area was equivalent to that of the PS plate.

Example 7 A printing plate was obtained in the same manner as in Example 1 except that tin and carbon were co-deposited at a thickness of 250 angstroms as a heat-sensitive layer in a ratio of 4: 1 (weight ratio). . In the printing evaluation, the hydrophilic swelling layer retained the ink repellency even after the printing was completed for 5000 sheets, and no ink stain was generated on the printed matter. Also, the degree of ink deposition on the image area was equivalent to that of the PS plate.

Example 8 A printing plate was obtained in the same manner as in Example 1 except that an 80 Å carbon thin film was provided on a 150 Å tin thin film by a vacuum evaporation method as a heat-sensitive layer. In the printing evaluation, the hydrophilic swelling layer retained the ink repellency even after the printing was completed for 5000 sheets, and no ink stain was generated on the printed matter. Also, the degree of ink deposition on the image area was equivalent to that of the PS plate.

Example 9 An aluminum plate having a thickness of 0.3 mm (manufactured by Sumitomo Light Metal Co., Ltd.) was
After applying the following composition, the composition was heated at 180 ° C. for 2 minutes to form an ink receiving layer having a thickness of 1.5 g / m ² .

<Ink receiving layer composition (parts by weight)> (1) 100 parts by weight of saponified polyvinyl acetate (degree of saponification: 45%) (2) 10 parts by weight of tetraethyl orthosilicate (3) γ-glycidoxy Propyltrimethoxysilane 5 parts by weight (4) 0.1 N hydrogen chloride aqueous solution 40 parts by weight (5) Purified water 150 parts by weight (6) Methyl ethyl ketone 200 parts by weight (7) Isopropyl alcohol 500 parts by weight Next, on the ink receiving layer An aluminum thin film layer having a thickness of 70 Å was provided by a sputtering method. Thereafter, a heat treatment was performed at 190 ° C. for 3 minutes.

Further, the following composition was applied using the hydrophilic polymer described in Synthesis Example 1, and then applied at 160 ° C. for 10 minutes.
After heat treatment, a hydrophilic swelling layer having a thickness of 2.5 g / m ² was applied.

<Composition of hydrophilic swelling layer (parts by weight)> (1) 90 parts by weight of hydrophilic polymer of Synthesis Example 1 (2) 5 parts by weight of tetraethylene glycol diglycidyl ether (4) 2-aminopropyltrimethoxysilane 5 Part by weight (5) 900 parts by weight of purified water Using a semiconductor laser (SLD-304XT, output 1 W, wavelength 809 nm, manufactured by Sony Corporation) equipped with the obtained laser-sensitive lithographic printing plate precursor on an XY table. ,
Pulse exposure was performed with a beam diameter of 20 μm and an exposure time of 10 μs.

Subsequently, the plate was washed with tap water for about 1 minute to obtain a printing plate.

The laser heat-sensitive layer and the hydrophilic swelling layer in the portion corresponding to the laser irradiation were destroyed by burning, and the ink receiving layer having the spot diameter corresponding to the beam diameter was exposed.

This lithographic printing plate was mounted on a plate cylinder of a lithographic printing machine, and printing was performed by supplying ink from an inking roller contacting the plate surface and simultaneously supplying water from a dampening solution supply device. As a result, the ink-receiving layer exposed portion (image portion) received the ink, and a clear ink pixel corresponding to the beam diameter was formed on the printed matter via the offset blanket cylinder.

On the other hand, the hydrophilic swelling layer was swollen by the fountain solution, and a printed matter having the same contrast as that of the PS plate completely repelling the ink was obtained. Even after printing was completed for 5000 sheets, the hydrophilic swelling layer retained the ink repellency, and no ink stains occurred on the printed matter. Also, the degree of ink deposition on the image area was equivalent to that of the PS plate.

Example 10 Example 8 except that the following ink receiving layer composition was used.
A printing plate precursor was obtained and evaluated in the same manner as above, and a good printed matter was obtained. After 5,000 sheets of printing were completed, the hydrophilic swelling layer retained the ink repellency, and the printed matter was stained with ink. Did not. Also, the degree of ink deposition on the image area was equivalent to that of the PS plate.

<Ink receiving layer composition (parts by weight)> (1) 70 parts by weight of polyvinylpyrrolidone (2) 70 parts by weight of polyvinylphosphonic acid (3) 260 parts by weight of purified water (4) 600 parts by weight of isopropyl alcohol Example 11 Example 8 except that the following ink receiving layer composition was used.
A printing plate precursor was obtained and evaluated in the same manner as above, and a good printed matter was obtained. After 5,000 sheets of printing were completed, the hydrophilic swelling layer retained the ink repellency, and the printed matter was stained with ink. Did not. Also, the degree of ink deposition on the image area was equivalent to that of the PS plate.

<Ink receiving layer composition (parts by weight)> (1) 20 parts by weight of polyurethane resin "Nipporan 3124" (Nippon Polyurethane Industry Co., Ltd.) (2) Polyisocyanate "Coronate L" (Nippon Polyurethane Industry Co., Ltd.) 10 parts by weight (3) 80 parts by weight of butyl acetate (4) 40 parts by weight of methyl ethyl ketone Example 12 Example 8 except that the following ink receiving layer composition was used.
A printing plate precursor was obtained and evaluated in the same manner as above, and a good printed matter was obtained. After 5,000 sheets of printing were completed, the hydrophilic swelling layer retained the ink repellency, and the printed matter was stained with ink. Did not. Also, the degree of ink deposition on the image area was equivalent to that of the PS plate.

<Ink receiving layer composition (parts by weight)> (1) 15 parts by weight of resole resin (2) 85 parts by weight of diglyme Example 13 The lithographic printing plate used in Example 1 and a normal PS plate (FNS;
A plate obtained by exposing and developing a Fuji Photo Film Co., Ltd.) was mounted on the same plate cylinder, and printing was performed in the same manner as in Example 1 while supplying commercially available purified water as dampening water. went.

When the supply amount of the dampening solution is increased from the standard condition, the ink density of the image area is extremely reduced in the portion where the PS plate is used, resulting in poor ink deposition due to so-called “water loss”. did. On the other hand, in the portion where the lithographic printing plate used in Example 1 was used, the degree of poor inking was slight.

Further, when the supply amount of the dampening solution was reduced from the standard condition, ink staining occurred on the entire surface of the portion using the PS plate. On the other hand, in the portion using the lithographic printing plate used in Example 1, good printed matter was obtained. The supply amount of dampening water was relatively compared with the dial scale value of the printing press. Table 2 shows the evaluation results.

[0150]

[Table 2] As described above, the lithographic printing plate of the present invention has a wide allowable range of dampening solution, and can obtain a good printed image using pure water as dampening solution.

[0151]

The laser-sensitive lithographic printing plate precursor of the present invention is capable of drawing by laser, has high ink repulsion in the printing process, and has a wide tolerance of dampening solution.
IPA-free dampening solution is possible and printing durability is excellent.

Claims (5)

[Claims] 1. A lithographic printing plate precursor comprising at least an ink receiving layer, a heat-sensitive layer, and a hydrophilic swelling layer provided in this order on a substrate, wherein the heat-sensitive layer is made of carbon and / or metal and has a thickness of 1000 Å or less. A thin film, wherein the ink receiving layer is a polymer compound obtained from a monomer having a hydroxyl group, a carbonyl group, a carboxyl group, an isocyanate group, an epoxy group, and / or a hydroxyl group, a carbonyl group,
A laser-sensitive lithographic printing plate precursor comprising a compound having a carboxyl group and an epoxy group. 2. The lithographic printing plate precursor as claimed in claim 1, wherein the heat-sensitive layer is formed by forming a carbon thin film on a metal thin film. 3. The melting point of the metal used for the heat-sensitive layer is 2000
(K) The laser-sensitive lithographic printing plate precursor according to any one of claims 1 to 2, wherein: 4. The method according to claim 1, wherein the metal is at least one metal selected from the group consisting of titanium, aluminum, nickel, iron, chromium, tellurium, tin, antimony, gallium, magnesium, polonium, selenium, thallium, zinc and bismuth. The laser-sensitive lithographic printing plate precursor according to claim 3, wherein the lithographic printing plate precursor is used. 5. The method for producing a laser-sensitive lithographic printing plate precursor according to claim 1, wherein the heating is performed at a temperature of 100 ° C. or more after providing the heat-sensitive layer.