JP2009248562A - Lithographic printing plate material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lithographic printing plate material in which process pollution by a powder drop in case of cutting the lithographic printing plate material in a predetermined size when producing the lithographic printing plate material by being no adverse influence to printing performance. <P>SOLUTION: In the lithographic printing plate material having a hydrophilic layer and an image forming layer in this order at the side of a supporting element, the hydrophilic layer or the image forming layer of the lithographic printing plate material contains a composite emulsion made of thermoplastic resin and inorganic particle. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a lithographic printing plate material, and more particularly to a lithographic printing plate material having a heat-sensitive image forming layer capable of image formation by a computer-to-plate (CTP) method.

  At present, in the field of printing, printing by the CTP method has been performed with the digitization of print image data. However, this printing is inexpensive and easy to handle and is equivalent to a conventional so-called PS plate. Therefore, there is a demand for a lithographic printing plate material for a CTP system having the following printability.

  In particular, in recent years, there has been a demand for a lithographic printing plate material that can be applied to a conventional printing machine without requiring development processing with a processing solution containing a special agent (for example, alkali, acid, solvent, etc.). Phase change lithographic printing plate material that does not require processing, lithographic printing plate material that is processed with water or a substantially neutral processing liquid mainly composed of water, and development processing at the initial stage of printing on a printing press There are known lithographic printing plate materials called chemical-free type lithographic printing plate materials and processless type lithographic printing plate materials, such as lithographic printing plate materials that do not particularly require a development step.

  As processless CTP, there are many on-machine development types in which non-image portions of an image forming layer are removed using dampening water or ink on a printing press. Examples include a lithographic printing plate material in which an image forming layer containing thermoplastic fine particles, a water-soluble binder, and a photothermal conversion material is provided on a hydrophilic layer or aluminum grain as disclosed in Japanese Patent No. 2938398.

  In this configuration, the photothermal conversion material in the image forming layer generates heat by infrared laser exposure, and the thermoplastic fine particles are thermally fused to form a water-resistant image area. Therefore, the heat generated in the exposed part of the image forming layer is rapidly conducted to the aluminum grain.

  For this reason, it becomes difficult to increase the temperature in the vicinity of the interface between the image forming layer and the aluminum grain, and it is difficult to fuse the image forming layer material to the aluminum grain, which is necessary for image formation. The energy is high (low sensitivity), and the adhesiveness of the image area tends to be insufficient (low printing durability).

  As one of the constitutions of the lithographic printing plate material for solving the above problems, various lithographic printing plate materials for infrared laser recording having a hydrophilic layer containing photothermal conversion agent particles as a photothermal conversion material have been studied.

  For example, a lithographic plate comprising such a photothermal conversion agent particle and a thermosensitive image forming layer containing the above-mentioned thermoplastic fine particles and a water-soluble material on a hydrophilic layer containing the photothermal conversion agent. A planographic printing plate material having a constitution in which a hydrophobic thin layer is provided on a hydrophilic layer containing a printing plate material or a photothermal conversion agent is known (see Patent Document 1 and Patent Document 2).

  These lithographic printing plate materials are coated with a coating solution for a hydrophilic layer and dried to form a thermal image forming layer thereon.

However, in these lithographic printing plate materials, the inorganic particle component of the hydrophilic layer is likely to fall off, and the non-image area may be smudged or may become cloudy during printing, particularly during printing. In order to improve these, there is known a technique for cleaning particles that easily fall off the surface after applying a hydrophilic layer using a magnetic force or the like. (See Patent Document 3)
However, in this case, falling off from the printing plate surface can be prevented, but correspondence to powder falling when cutting a lithographic printing plate material to a predetermined size is insufficient.

  As a method for suppressing these powder falling off, there is a means for increasing the strength by including a thermoplastic resin in the hydrophilic layer. However, when a normal general thermoplastic resin is used, the hydrophilic layer This has caused the occurrence of printing stains by degrading the hydrophilicity of the ink.

Further, as another technique, there is a lithographic printing plate material having a hydrophilic image-forming layer that becomes hydrophobic by heat, containing a hydrophobizing precursor and an organic-inorganic composite on a support, and the organic-inorganic A technique is disclosed in which a lithographic printing plate is obtained by hydrolysis and polycondensation of a complex under the condition in which a metal complex compound and an organic hydrophilic resin coexist (see Patent Document 4). However, in this case, since the organic-inorganic composite is included in the hydrophilic layer that is hydrophobized by heat, there is a problem that stains are likely to occur during printing.
JP 2000-225780 A JP 2000-355178 A JP 2004-189439 A JP 2002-25484 A

  As a result of intensive studies, the inventors of the present invention, as a method for suppressing the above-mentioned powder omission, include the composite emulsion composed of the thermoplastic resin according to the present invention and the inorganic particles in the above-described hydrophilic layer. During the cutting without degrading the developability due to the decrease in hydrophilicity, because the small hydrophilic colloidal silica particles wraps around the polymer particles with large hydrophobicity while firmly linking them with chemical bonds, making them suitably hydrophilic. I found that it was possible to improve the powder fall.

  Furthermore, the inclusion of a composite emulsion composed of the thermoplastic resin and inorganic particles according to the present invention in the image forming layer improves the durability (printing durability at the time of printing) as a lithographic printing plate, It was also found that both blanket stains can be reduced.

  The present invention has been made in view of the above problems, and an object of the present invention is to significantly reduce process contamination caused by powder falling when cutting to a predetermined size during production of a lithographic printing plate material without adversely affecting printing performance. Is to provide a lithographic printing plate material.

  The above object of the present invention can be achieved by the following constitution.

  1. In the lithographic printing plate material having a hydrophilic layer and an image forming layer in this order from the support side on the support, the hydrophilic layer or the image forming layer contains a composite emulsion comprising a thermoplastic resin and inorganic particles. A planographic printing plate material.

  2. 2. The lithographic printing plate material according to 1, wherein the support surface is an anodized film of aluminum.

  3. The lithographic printing plate material according to 1 or 2, wherein the hydrophilic layer contains at least colloidal silica.

  4). The lithographic printing plate as described in any one of 1 to 3, wherein the composite emulsion comprising the thermoplastic resin and inorganic particles comprises at least a styrene / acrylic copolymer resin or an acrylic copolymer resin, and colloidal silica. Printing plate material.

  ADVANTAGE OF THE INVENTION According to this invention, the lithographic printing plate material which reduced remarkably the process contamination by the powder fall at the time of cutting to a predetermined size at the time of production of a lithographic printing plate material can be provided without the bad influence on printing performance.

  Furthermore, it is possible to provide a planographic printing plate material that can achieve both improvement in printing durability during printing and reduction of blanket stains after printing.

  Hereinafter, although the best mode for carrying out the present invention will be described, the present invention is not limited to these.

  The lithographic printing plate material of the present invention is a lithographic printing plate material having a hydrophilic layer and an image forming layer on a support, and the hydrophilic layer or the image forming layer contains a composite emulsion composed of a thermoplastic resin and inorganic particles. It is characterized by that.

[Hydrophilic layer]
The hydrophilic layer and the material constituting the hydrophilic layer according to the present invention will be described.

<Photothermal conversion agent particles>
The hydrophilic layer according to the present invention preferably contains photothermal conversion agent particles.

  The photothermal conversion agent particle is a particle having a function capable of generating an image in the heat-sensitive image forming layer by generating heat by image exposure, and is a metal oxide particle or a particle whose surface is coated with a metal oxide.

  As the particle size of the photothermal conversion agent particles, the average primary particle size is preferably 1 μm or less, and the average primary particle size is more preferably in the range of 0.01 to 0.5 μm.

  When the average primary particle diameter is 1 μm or less, the photothermal conversion ability with respect to the addition amount becomes better, and when the average primary particle diameter is within the range of 0.01 to 0.5 μm, the photothermal conversion ability with respect to the addition amount is obtained. Better.

  As the metal oxide agent particles, it is possible to use a material that is black in the visible light region, or a particle that is made of a material that has conductivity or is a semiconductor.

Examples of the former include black iron oxide (Fe ₃ O ₄ ) and black mixed metal oxides containing two or more metals.

Examples of the latter include Sb-doped SnO ₂ (ATO), Sn-added In ₂ O ₃ (ITO), TiO ₂ , and TiO ₂ reduced TiO (titanium oxynitride, generally titanium black). Can be mentioned.

Further, it can also be used those obtained by coating the core material _{(BaSO 4, TiO 2, 9Al} 2 O 3 · 2B 2 O, K 2 O · nTiO 2 , etc.) in these metal oxides.

  Among these photothermal conversion agent particles, black iron oxide and a black composite metal oxide containing two or more metals are more preferable materials.

  The black iron oxide particles are preferably particles having an acicular ratio (major axis diameter / minor axis diameter) in the range of 1 to 1.5, and are substantially spherical (acicular ratio 1), or It preferably has an octahedral shape (acicular ratio of about 1.4).

  Examples of such black iron oxide particles include TAROX series manufactured by Titanium Industry Co., Ltd.

  As the spherical particles, BL-100 (particle diameter 0.2 to 0.6 μm), BL-500 (particle diameter 0.3 to 1.0 μm) and the like can be preferably used.

  In addition, as octahedral particles, ABL-203 (particle diameter 0.4 to 0.5 μm), ABL-204 (particle diameter 0.3 to 0.4 μm), ABL-205 (particle diameter 0.2 to 0). .3 μm), ABL-207 (particle diameter 0.2 μm) and the like can be preferably used.

Moreover, these surfaces of the particles can also be preferably used particles coated with an inorganic material such as SiO _2, as such particles, spherical particles coated with SiO _2: BL-200 (particle size from 0.2 to 0 .3 μm), octahedral shaped particles: ABL-207A (particle diameter 0.2 μm).

  As the black composite metal oxide particles containing two or more kinds of metals, specifically, two or more kinds selected from Al, Ti, Cr, Mn, Fe, Co, Ni, Cu, Zn, Sb and Ba are used. Examples thereof include composite metal oxide particles made of metal.

  These are disclosed by methods disclosed in JP-A-8-27393, JP-A-9-25126, JP-A-9-237570, JP-A-9-241529, JP-A-10-231441, and the like. Can be manufactured.

  The composite metal oxide that can be used in the present invention is particularly preferably a Cu-Cr-Mn-based or Cu-Fe-Mn-based composite metal oxide.

  In the case of a Cu—Cr—Mn system, it is preferable to perform the treatment disclosed in JP-A-8-27393 in order to reduce the elution of hexavalent chromium.

  Examples of the particles whose surfaces are coated with a metal oxide include metal particles, carbon black particles, and graphite particles described later.

  Since a thin oxide film is formed on the surface of the metal particles, it can be said that the particles are coated with the metal oxide.

  As the metal, any metal can be used as long as the particle diameter is 0.5 μm or less, preferably 100 nm or less, more preferably 50 nm or less. The shape may be any shape such as a spherical shape, a piece shape, or a needle shape. Colloidal metal fine particles (Ag, Au, etc.) are particularly preferable.

  Moreover, the iron alloy particle | grains which have the magnetism described in Unexamined-Japanese-Patent No. 2000-3551788 can also be used.

  As the carbon black particles, it is particularly preferable to use furnace black or acetylene black. The particle size (d50) is preferably 100 nm or less, and more preferably 50 nm or less.

  As the graphite particles, fine particles having a particle size of 0.5 μm or less, preferably 100 nm or less, more preferably 50 nm or less can be used.

  These carbon black particles and graphite particles can be used in the present invention, for example, by coating the surface with a metal oxide using a method as described in JP-A No. 2000-3551788.

Further, metal oxide particles or those obtained by further coating metal particles with a metal oxide such as SiO ₂ can be preferably used.

  The addition amount of these photothermal conversion agent particles is preferably 0.1 to 90% by mass with respect to the hydrophilic layer, but is preferably 15% by mass or more. For coexistence with printing durability, the content is more preferably 15 to 70% by mass, and further preferably 15 to 50% by mass.

  As the photothermal conversion agent particles according to the present invention, those having functions as the following hydrophilic materials can also be preferably used.

<Other materials that can be contained in the hydrophilic layer>
The hydrophilic layer according to the present invention contains a hydrophilic material. A metal oxide is preferably used as the hydrophilic material.

  The metal oxide is preferably used in the form of metal oxide fine particles.

  Examples thereof include colloidal silica, alumina sol, titania sol, and other metal oxide sols.

  The form of the metal oxide fine particles may be spherical, needle-like, feather-like, or any other form. The average particle diameter is preferably 3 to 100 nm, and several kinds of metal oxide fine particles having different average particle diameters can be used in combination. The surface of the particles may be surface treated.

  The metal oxide fine particles can be used as a binder by utilizing the film forming property. The decrease in hydrophilicity is less than when an organic binder is used, and it is suitable for use in a hydrophilic layer.

  Among the above, colloidal silica can be preferably used in the present invention. Colloidal silica has the advantage of high film-forming properties even under relatively low temperature drying conditions, and good strength can be obtained even in a layer in which the material containing no carbon atom is 91% by mass or more.

  Further, it is known that the colloidal silica has a stronger binding force as the particle diameter is smaller, and it is preferable to use colloidal silica having an average particle diameter of 20 nm or less in the present invention, and more preferably 3 to 15 nm. preferable.

  In addition, as described above, alkaline colloidal silica is particularly preferable because alkaline colloidal silica has a high effect of suppressing the occurrence of soiling.

  Alkaline colloidal silica having an average particle size within this range includes “Snowtex-20 (particle size 10-20 nm)”, “Snowtex-30 (particle size 10-20 nm)”, “Snowtex” manufactured by Nissan Chemical Co., Ltd. -40 (particle diameter 10-20 nm) "," Snowtex-N (particle diameter 10-20 nm) "," Snowtex-S (particle diameter 8-11 nm) "," Snowtex-XS (particle diameter 4-6 nm) ) ".

  The hydrophilic layer according to the present invention preferably contains porous metal oxide particles as a metal oxide as a hydrophilic material.

  As the porous metal oxide particles, porous silica, porous aluminosilicate particles, or zeolite particles described later can be preferably used.

  Porous silica Porous silica or porous aluminosilicate particles Porous silica particles are generally produced by a wet method or a dry method. In the wet method, it can be obtained by drying and pulverizing a gel obtained by neutralizing an aqueous silicate solution, or by pulverizing a precipitate deposited after neutralization.

  The porosity of the particles is preferably 1.0 ml / g or more in terms of pore volume before dispersion, more preferably 1.2 ml / g or more, and 1.8 to 2.5 ml / g. More preferably, it is as follows.

  A hydrophilic organic resin may be contained in the hydrophilic layer.

  Examples of hydrophilic organic resins include polyethylene oxide, polypropylene oxide, polyvinyl alcohol, polyethylene glycol (PEG), polyvinyl ether, styrene-butadiene copolymer, conjugated diene polymer latex of methyl methacrylate-butadiene copolymer, and acrylic. Resins such as polymer latex, vinyl polymer latex, polyacrylamide, and polyvinylpyrrolidone, and saccharides may be mentioned.

  In addition, the resin may contain a cationic resin. Examples of the cationic resin include polyalkylene polyamines such as polyethylene amine and polypropylene polyamine or derivatives thereof, and acrylic resins having a tertiary amino group or a quaternary ammonium group. , Diacrylamine and the like. The cationic resin may be added in the form of fine particles. Examples thereof include a cationic microgel described in JP-A-6-161101.

  As the saccharide, an oligosaccharide can be used, but it is particularly preferable to use a polysaccharide.

  As polysaccharides, starches, celluloses, polyuronic acids, pullulans and the like can be used, but cellulose derivatives such as methyl cellulose salts, carboxymethyl cellulose salts, hydroxyethyl cellulose salts are particularly preferable, and sodium salts and ammonium salts of carboxymethyl cellulose are preferable. More preferred.

  This is because an effect of forming the surface shape of the hydrophilic layer in a preferable state can be obtained by including the polysaccharide in the hydrophilic layer.

  The surface of the hydrophilic layer preferably has a concavo-convex structure with a pitch of 0.1 to 50 μm like the aluminum grain of the PS plate, and this concavo-convex improves water retention and image area retention.

  Such a concavo-convex structure can be formed by containing an appropriate amount of a filler having an appropriate particle size in the hydrophilic layer, but the above-mentioned alkaline colloidal silica and the above-mentioned water-soluble substance are used in the hydrophilic layer coating solution. It is preferable that a structure having better printing performance can be obtained by containing a polysaccharide and forming a phase separation when the hydrophilic layer is applied and dried.

  Moreover, as a film thickness of a hydrophilic layer, it is 0.01-50 micrometers, Preferably it is 0.2-10 micrometers, More preferably, it is 0.5-3 micrometers.

  The coating liquid for the hydrophilic layer is used for the hydrophilic layer described above and comprises a material and a coating solvent.

  As the coating solvent, water is preferably used, but a solvent compatible with water, such as alcohols, can also be contained.

  Further, the hydrophilic layer coating solution may contain a water-soluble surfactant for the purpose of improving the coating property.

  Although surfactants such as Si-based, F-based, and acetylene glycol can be used, it is particularly preferable to use a surfactant containing Si element because there is no fear of causing printing stains.

  The content of the surfactant is preferably 0.01 to 3% by mass, more preferably 0.03 to 1% by mass, based on the entire hydrophilic layer (solid content as the coating solution).

  In addition, the hydrophilic layer according to the present invention can contain a phosphate. In the present invention, since the hydrophilic layer coating solution is preferably alkaline, the phosphate is preferably added as trisodium phosphate or disodium hydrogen phosphate. By adding phosphate, the effect of improving the mesh opening at the time of printing can be obtained. The addition amount of phosphate is preferably 0.1 to 5% by mass, and more preferably 0.5 to 2% by mass as an effective amount excluding hydrate.

  The hydrophilic layer according to the present invention contains photothermal conversion agent particles for forming an image by image-like heating by image exposure. In such a lithographic printing plate material, photothermal conversion in the hydrophilic layer is performed. The content ratio of the agent particles affects the sensitivity, and in order to increase the sensitivity, it is necessary to increase the content ratio of the photothermal conversion agent particles.

  However, simply increasing the content ratio of the photothermal conversion agent particles has a problem in that the bonding strength of the hydrophilic layer as a coating film may decrease.

  This is because when the content ratio of the photothermal conversion agent particles in the hydrophilic layer increases, the ratio of the hydrophilic binder for holding and fixing the photothermal conversion agent particles in the layer decreases, and the holding ability of the photothermal conversion agent particles is reduced. Estimated to decrease.

  As a method of suppressing the falling off of the photothermal conversion agent particles, the strength is improved by controlling the crosslinking of the hydrophilic binder, the surface treatment of the photothermal conversion agent particles is performed to improve the binding force with the binder, etc. Although it is possible to improve the holding | maintenance capability of a photothermal conversion agent particle | grain by improving the coating-film intensity | strength of hydrophilic layer itself, this method has the large fall of the hydrophilic property of a hydrophilic layer.

<Composite emulsion composed of thermoplastic resin and inorganic particles according to the present invention>
In one aspect of the present invention, the hydrophilic layer contains a composite emulsion composed of the thermoplastic resin according to the present invention and inorganic particles.

  The “composite emulsion composed of thermoplastic resin and inorganic particles” according to the present invention includes, for example, an emulsion in which small colloidal silica particles are chemically bonded around polymer particles. Specifically, Nichigo Movinyl Co., Ltd., Movinyl 8000 series, etc.

  The composite emulsion comprising a thermoplastic resin and inorganic particles is preferably a composite emulsion comprising at least a styrene / acrylic copolymer resin or an acrylic copolymer resin and colloidal silica.

  By using a composite emulsion composed of the thermoplastic resin and inorganic particles according to the present invention for the hydrophilic layer, a fine fineness is achieved by the balance between thermal fusion between the resin polymers and suppression of film formation of highly hydrophilic colloidal silica particles. It is presumed that pores can be formed, the strength of the coating film can be secured, and at the same time, the hydrophilicity can be kept high.

  The content of the composite emulsion comprising the thermoplastic resin according to the present invention and inorganic particles in the hydrophilic layer is usually 1 to 50% by mass.

<Application and drying method>
As a coating method for coating the hydrophilic layer coating liquid on a support described later, any known coating method such as bar coating, roll coating, and extrusion coating may be used. it can.

  The drying temperature is preferably 70 ° C. or higher. When a support body is resin, it is more preferable that it is the range of 80-150 degreeC. Moreover, when a support body is a metal, it is more preferable that it is the range of 80 to 300 degreeC.

  The drying time is preferably in the range of 1 second to 5 minutes, and more preferably in the range of 5 to 2 minutes. Further, depending on the combination of the drying temperature and the drying time, the support may be damaged by heat, and therefore, it is preferable that the support is not damaged.

[Support]
As the support, a known material used as a substrate of a printing plate can be used.

  Examples thereof include a metal plate, a plastic film, paper treated with polyolefin, a composite support obtained by appropriately bonding the above materials, and the like. The thickness of the support is not particularly limited as long as it can be attached to a printing press, but a thickness of 50 to 500 μm is generally easy to handle.

  Examples of the metal plate include iron, stainless steel, and aluminum. Aluminum is particularly preferable from the relationship between specific gravity and rigidity. The aluminum plate is usually used after degreasing with an alkali, an acid, a solvent or the like in order to remove oil used during rolling and winding existing on the surface. As the degreasing treatment, degreasing with an alkaline aqueous solution is particularly preferable. Moreover, in order to improve adhesiveness with a coating layer, it is preferable to perform an easily bonding process and undercoat layer application | coating to an application surface.

  For example, a method of dipping in a liquid containing a coupling agent such as a silicate or a silane coupling agent, or applying a liquid and then sufficiently drying may be mentioned. Anodizing treatment is also considered as a kind of easy adhesion treatment and can be used.

  In the present invention, the surface of the support is preferably an anodized aluminum film. Moreover, it can also use combining an anodizing process and the said immersion or application | coating process. An aluminum support roughened by a known method can also be used.

  Examples of the plastic film include polyethylene terephthalate, polyethylene naphthalate, polyimide, polyamide, polycarbonate, polysulfone, polyphenylene oxide, and cellulose esters.

  As the support according to the present invention, polyethylene terephthalate and polyethylene naphthalate are particularly preferable.

  These plastic films are preferably subjected to easy adhesion treatment or undercoat layer coating on the coated surface in order to improve adhesion with the coated layer. Examples of the easy adhesion treatment include corona discharge treatment, flame treatment, plasma treatment, and ultraviolet irradiation treatment. Examples of the undercoat layer include a layer containing gelatin or latex. The undercoat layer may contain an organic or inorganic known conductive material.

  In addition, a support provided with a back coat layer having a rough surface in order to control the slipperiness of the back face or a support provided with a back coat layer containing a known conductive material can be preferably used.

(Image forming layer)
After passing through the hydrophilic layer coating step, a lithographic printing plate material can be obtained by forming an image forming layer as described later.

  The image formation may be a so-called positive plate in which the image forming layer in the exposed portion is changed in a direction that is easily removed from the base having a hydrophilic surface by heat, or the image forming layer in the exposed portion. It may be a so-called negative plate that changes in a direction that is difficult to be removed by heat.

  A preferred embodiment of the lithographic printing plate material of the present invention is a negative lithographic printing plate material in which the image forming layer of the exposed portion changes in a direction that is difficult to be removed from the substrate having a hydrophilic surface by heat. is there.

  As such an image forming layer in which the exposed portion is changed in a direction in which it is difficult to remove the exposed portion from the hydrophilic layer by heat, for example, the hydrophilic layer can be made hydrophobic by changing the hydrophilic layer to hydrophobic by heat. Examples thereof include an image forming layer containing a precursor and a water-soluble or water-dispersible material.

  As the hydrophobizing precursor, for example, a polymer that changes from hydrophilic (water-soluble or water-swellable) to hydrophobic by heat, specifically, for example, aryldiazo disclosed in JP-A-2000-56449 Mention may be made of polymers containing sulfonate units.

  In the image forming layer according to the present invention, thermoplastic hydrophobic fine particles such as heat fusible fine particles and heat fusible fine particles can be preferably used as the hydrophobizing precursor.

  Examples of the thermoplastic hydrophobic fine particles include heat-meltable fine particles and heat-fusible fine particles, which will be described later.

  The heat-meltable fine particles are fine particles formed of a material that has a low viscosity when melted, and is generally classified as a wax, among thermoplastic materials. The physical properties are preferably a softening point of 40 ° C. or higher and 120 ° C. or lower, a melting point of 60 ° C. or higher and 150 ° C. or lower, more preferably a softening point of 40 ° C. or higher and 100 ° C. or lower, and a melting point of 60 ° C. or higher and 120 ° C. or lower. When the melting point is less than 60 ° C., storage stability is a problem, and when the melting point is higher than 300 ° C., ink deposition sensitivity is lowered.

  Usable materials include paraffin, polyolefin, polyethylene wax, microcrystalline wax, fatty acid wax and the like. These have a molecular weight of about 800 to 10,000. In order to facilitate emulsification, these waxes can be oxidized to introduce polar groups such as hydroxyl groups, ester groups, carboxyl groups, aldehyde groups, and peroxide groups. Furthermore, in order to lower the softening point and improve the workability, these waxes are stearamide, linolenamide, laurylamide, myristamide, hardened beef fatty acid amide, palmitoamide, oleic acid amide, rice sugar fatty acid amide, coconut fatty acid amide. Alternatively, methylolated products of these fatty acid amides, methylene bisstellaramide, ethylene bisstellaramide, and the like can be added. Coumarone-indene resin, rosin-modified phenol resin, terpene-modified phenol resin, xylene resin, ketone resin, acrylic resin, ionomer, and copolymers of these resins can also be used.

  Among these, it is preferable to contain any of polyethylene, microcrystalline, fatty acid ester, and fatty acid. Since these materials have a relatively low melting point and a low melt viscosity, high-sensitivity image formation can be performed. Further, since these materials have lubricity, damage when a shearing force is applied to the surface of the lithographic printing plate material is reduced, and resistance to printing stains due to scratches or the like is improved.

  The heat-meltable fine particles are preferably dispersible in water, and the average particle diameter is preferably 0.01 to 10 μm, more preferably 0.1 to 3 μm. When the average particle diameter is smaller than 0.01 μm, when the coating liquid for the layer containing the heat-meltable fine particles is applied onto the porous hydrophilic layer described later, the heat-meltable fine particles are not removed from the pores of the hydrophilic layer. It becomes easy to enter inside or into the gaps between fine irregularities on the surface of the hydrophilic layer, and the on-press development becomes insufficient, which may cause scumming. When the average particle size of the heat-meltable fine particles is larger than 10 μm, the resolution is lowered.

  Further, the composition of the heat-meltable fine particles may vary continuously between the inside and the surface layer, or may be coated with a different material.

  As a coating method, a known microcapsule formation method, a sol-gel method, or the like can be used.

  As content of the heat-meltable microparticles | fine-particles in a layer, 1-90 mass% of the whole layer is preferable, and 5-80 mass% is more preferable.

  Examples of the heat-fusible fine particles include thermoplastic hydrophobic polymer fine particles, and there is no specific upper limit for the softening temperature of the polymer fine particles, but the temperature is lower than the decomposition temperature of the polymer fine particles. Is preferred. The weight average molecular weight (Mw) of the polymer is preferably in the range of 10,000 to 1,000,000.

  Specific examples of the polymer constituting the polymer particles include, for example, diene (co) polymers such as polypropylene, polybutadiene, polyisoprene, and ethylene-butadiene copolymer, styrene-butadiene copolymer, Synthetic rubbers such as methyl methacrylate-butadiene copolymer, acrylonitrile-butadiene copolymer, polymethyl methacrylate, methyl methacrylate- (2-ethylhexyl acrylate) copolymer, methyl methacrylate-methacrylic acid copolymer, methyl acrylate- ( N-methylolacrylamide) copolymer, (meth) acrylic acid ester such as polyacrylonitrile, (meth) acrylic acid (co) polymer, polyvinyl acetate, vinyl acetate-vinyl propionate copolymer, vinyl acetate-ethylene copolymer Vinyl etc. of polymers Ester (co) polymer, vinyl acetate - (2-ethylhexyl acrylate) copolymers, polyvinyl chloride, polyvinylidene chloride, polystyrene and copolymers thereof. Of these, (meth) acrylic acid esters, (meth) acrylic acid (co) polymers, vinyl ester (co) polymers, polystyrene, and synthetic rubbers are preferably used.

  The heat-fusible fine particles are preferably dispersible in water, and the average particle diameter is preferably 0.01 to 10 μm, more preferably 0.1 to 10 m from the viewpoint of on-press developability and sensitivity. ~ 3 μm.

  Further, the composition of the heat fusible particles may be continuously changed between the inside and the surface layer, or may be coated with a different material.

As a coating method, a known microcapsule formation method, a sol-gel method, or the like can be used.
As content of the thermoplastic fine particle in a layer, 1-90 mass% of the whole layer is preferable, and 5-80 mass% is more preferable.

  Examples of the microcapsules include microcapsules enclosing a hydrophobic material described in JP-A No. 2002-2135 and JP-A No. 2002-19317.

  The microcapsules preferably have an average diameter of 0.1 to 10 μm, more preferably 0.3 to 5 μm, and even more preferably 0.5 to 3 μm.

  The image forming layer may contain a water-soluble material, and examples of the water-soluble material include the following materials.

<Water-soluble polymer compound>
Examples of the water-soluble material contained in the image forming layer include known water-soluble polymer compounds that dissolve in an aqueous solution having a pH of 4 to 10.

  Specific examples include resins such as polysaccharides, polyethylene oxide, polypropylene oxide, polyvinyl alcohol, polyethylene glycol (PEG), polyvinyl ether, polyacrylic acid, polyacrylate, polyacrylamide, and polyvinylpyrrolidone.

  Of these, polysaccharides, polyacrylic acid, polyacrylates, polyacrylamide, and polyvinylpyrrolidone are preferable.

  As polysaccharides, starches, celluloses, polyuronic acids, pullulan, chitosan, or derivatives thereof can be used, and cellulose derivatives such as methyl cellulose salts, carboxymethyl cellulose salts, and hydroxyethyl cellulose salts are particularly preferable. Carboxymethyl cellulose The sodium salt and ammonium salt are more preferable.

  The polyacrylic acid, polyacrylate, and polyacrylamide preferably have a molecular weight of 3,000 to 1,000,000, and more preferably 5,000 to 500,000.

  Of these, polyacrylates such as sodium polyacrylate are most preferred. The polyacrylate is highly effective as a hydrophilic treatment agent for the hydrophilic layer, and can improve the hydrophilicity of the surface of the hydrophilic layer that appears when the image forming layer is developed on the machine.

<Oligosaccharide>
As a water-soluble material, an oligosaccharide can be contained in addition to the water-soluble polymer compound described above.

  Examples of the oligosaccharide include raffinose, trehalose, maltose, galactose, sucrose, and lactose, and trehalose is particularly preferable.

<Other materials that can be contained in the image forming layer>
The image forming layer may contain an infrared absorbing dye as a photothermal conversion material. As the content of the infrared absorbing dye, it is necessary to consider the balance with the printing press contamination during on-press development depending on the degree of coloring of the dye with visible light. as, 0.001 g / ^{m 2} or more, preferably less than 0.2 g / ^{m 2,} more preferably less than 0.05 g / ^{m 2.} Needless to say, it is preferable to use a pigment that is less colored with visible light.

  Specific examples of the infrared absorbing dye include known ones.

  The image forming layer can contain a surfactant. A surfactant such as Si-based or F-based can be used, but it is particularly preferable to use a surfactant containing Si element because there is no fear of causing printing stains. The content of the surfactant is preferably 0.01 to 3% by mass, more preferably 0.03 to 1% by mass, based on the entire hydrophilic layer (solid content as the coating solution).

  Further, it may contain an acid (phosphoric acid, acetic acid, etc.) or an alkali (sodium hydroxide, silicate, phosphate, etc.) for pH adjustment.

<Composite emulsion composed of thermoplastic resin and inorganic particles according to the present invention>
In another embodiment of the present invention, the image forming layer according to the present invention contains a composite emulsion comprising the thermoplastic resin according to the present invention and inorganic particles.

  According to still another aspect of the present invention, the image forming layer and the hydrophilic layer according to the present invention contain a composite emulsion comprising the thermoplastic resin according to the present invention and inorganic particles.

  As the composite emulsion composed of the thermoplastic resin and the inorganic particles in the present invention, the same emulsion as described in the hydrophilic layer can be preferably used. These are presumed to improve the durability of the printing plate in order to enhance the binding between the organic component of the image forming layer and the inorganic component of the hydrophilic layer.

  The content of the composite emulsion comprising the thermoplastic resin according to the present invention and inorganic particles in the image forming layer is usually 1 to 50% by mass.

[Image heating]
The lithographic printing plate material of the present invention is image-wise heated and then developed on-press by an on-press development method described below to be ready for printing.

  As a method for imagewise heating, there is a method of heating by a medium such as a thermal head or irradiation of laser light as described above, but a method using laser light is preferable in the present invention. Among the methods using laser light, it is particularly preferable to form an image by exposure with a thermal laser.

  For example, scanning exposure using a laser that emits light in the infrared and / or near infrared region, that is, emits light in the wavelength range of 700 to 1500 nm is preferable.

  A gas laser may be used as the laser, but it is particularly preferable to use a semiconductor laser that emits light in the near infrared region.

  As an apparatus suitable for scanning exposure, any apparatus may be used as long as it can form an image on the surface of a lithographic printing plate material in accordance with an image signal from a computer using this semiconductor laser.

  In general, (1) a method of exposing the entire surface of the lithographic printing plate material by performing two-dimensional scanning on the lithographic printing plate material held by the flat plate holding mechanism using one or a plurality of laser beams; (2) A lithographic printing plate material held along a cylindrical surface inside a fixed cylindrical holding mechanism, using one or a plurality of laser beams from the inside of the cylinder in the circumferential direction of the cylinder (main scanning) (3) a surface of a cylindrical drum that rotates about an axis as a rotating body, and is moved in a direction (sub-scanning direction) perpendicular to the circumferential direction while scanning in the direction). The held lithographic printing plate material is scanned in the circumferential direction (main scanning direction) by rotating the drum using one or a plurality of laser beams from the outside of the cylinder, and the direction perpendicular to the circumferential direction (sub-scanning direction) Move the lithographic printing plate material to It includes a method of exposing a. In particular, in an apparatus that performs exposure on a printing apparatus, the exposure method (3) is used.

[On-press development method]
As a lithographic printing method, an unexposed portion of a lithographic printing material exposed by image exposure is removed on a printing machine during printing to be a non-image portion, and printing is performed.

  The removal of the unexposed portion of the image forming layer on the printing press can be performed by contacting a watering roller or an ink roller while rotating the plate cylinder. The various sequences can be performed.

In that case, the water amount may be adjusted by increasing or decreasing the amount of dampening water required for printing, and the water amount adjustment may be divided into multiple stages or steplessly. You may change it to.
(1) As a sequence for starting printing, a watering roller is brought into contact with the plate cylinder to make one to several dozen rotations, then an ink roller is brought into contact with the plate cylinder to make one to several dozen rotations, and then printing is performed. Start.
(2) As a sequence for starting printing, an ink roller is brought into contact with the plate cylinder to make one to several tens of turns, then a watering roller is brought into contact with the plate cylinder to make one to several tens of turns, and then printing is performed. Start.
(3) As a sequence for starting printing, the watering roller and the ink roller are brought into contact with each other substantially simultaneously to rotate the plate cylinder one to several tens of times, and then printing is started.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in detail, this invention is not limited to these. In addition, unless otherwise indicated, "part" in an Example shows a "mass part".

Example 1
(Production of support)
An aluminum plate (material 1050, tempered H16) having a thickness of 0.24 mm was immersed in a 1% by mass sodium hydroxide aqueous solution at 50 ° C., dissolved so that the dissolved amount became 2 g / m ² , and washed with water. Then, it was immersed in 0.1 mass% hydrochloric acid aqueous solution at 25 ° C. for 30 seconds, neutralized, and then washed with water.

Next, this aluminum plate was subjected to electrolytic surface roughening treatment with an electrolytic solution containing hydrochloric acid 10 g / L and aluminum 0.5 g / L using a sine wave alternating current and a peak current density of 50 A / dm ^2. It was. The distance between the electrode and the sample surface at this time was 10 mm. Perform electrolytic graining treatment is divided into 12 times, and the quantity of electricity used in one treatment (at a positive polarity) as the 40C / dm ^2, treatment quantity of electricity 480C / dm ² in total (at a positive polarity). In addition, a rest period of 5 seconds was provided between each surface roughening treatment.

After the electrolytic surface roughening, it is immersed in a 1% by mass aqueous sodium hydroxide solution maintained at 50 ° C. and etched so that the dissolution amount including the smut of the roughened surface becomes 1.2 g / m ^2. Then, it was washed with water, then immersed in a 10% aqueous sulfuric acid solution maintained at 25 ° C. for 10 seconds, neutralized, and then washed with water. Next, an anodized film was formed by anodizing in a 20% sulfuric acid aqueous solution so that the amount of electricity was 150 C / dm ² under a constant voltage condition of 20 V, and further washed with water.

  Next, after squeezing the surface water after washing with water, it was immersed in a 1% by mass sodium dihydrogen phosphate aqueous solution maintained at 70 ° C. for 30 seconds, washed with water, dried at 80 ° C. for 5 minutes, and the support 1 Got. Ra of the support 1 was 460 nm (measured at 40 times using RST Plus manufactured by WYKO).

(Preparation of hydrophilic layer reference coating solution)
A material having the composition shown in Table 1 below was mixed and dispersed for 10 minutes at a rotational speed of 10,000 using a homogenizer.

  Next, this was filtered to obtain a hydrophilic layer reference coating solution having a solid content of 20% by mass.

  Composition of hydrophilic layer reference coating solution

  To 100 parts by mass of the above-mentioned hydrophilic layer reference coating solution, a “particulate emulsion according to the present invention or comparative emulsion” according to Table 2 adjusted to a solid content of 20% by mass was added in parts by mass as shown in Table 2. 2, hydrophilic layer coating solutions 1 to 4 were prepared.

(Coating and drying of hydrophilic layer coating solution)
With a coating line having two coaters / drying sections, the hydrophilic layer coating liquids 1 to 4 on the support 1 described above are transported at a line speed of 30 m / min. It was coated and dried so as to have a thickness of 0.0 μm, a hydrophilic layer was formed by coating, and the film was wound up in a roll shape with the hydrophilic layer on the inside.

(Aging process)
A hydrophilic layer was applied and formed, and the wound sample roll was placed in a constant temperature oven at 60 ° C. and subjected to an aging treatment for 48 hours.

<< Preparation of planographic printing plate materials 101-104 >>
(Preparation of image forming layer coating solution)
A material having the following composition was sufficiently mixed and stirred and filtered to prepare an image forming layer coating solution 1 having a solid content of 10% by mass.

The following image forming layer coating solution 1 is applied to the hydrophilic layer of the sample that has been coated, dried and aged by applying the above hydrophilic layer coating solution, and the dry weight is 0.7 g / m ² using a wire bar. And dried at 55 ° C. for 1 minute. Subsequently, an aging treatment at 40 ° C. for 24 hours was performed to obtain planographic printing plate materials 101 to 104.

(Composition of image forming layer coating solution 1)
Carnauba wax emulsion: A118 (manufactured by Gifu Shellac Co., Ltd., average particle size 0.3 μm, softening point 65 ° C., melting point 80 ° C., melt viscosity 8 ° cps at 140 ° C., solid content 40% by mass)
17 parts aqueous solution of disaccharide trehalose (trade name Treha, Hayashibara Shoji Co., Ltd., melting point 97 ° C.), solid content 20% by mass 12 parts sodium polyacrylate: aqueous solution of Aqualic DL522 (manufactured by Nippon Shokubai Co., Ltd.), solid content 10% by mass 6 parts Photothermal conversion dye: 1% by weight aqueous solution of ADS830WS (manufactured by American Dye Source) 55 parts Pure water 10 parts << Preparation of Lithographic Printing Plate Materials 201-204 >>
Table 3 wherein 100 parts by mass of the image-forming layer coating solution 1 is adjusted to a solid content of 20% by mass on the hydrophilic layer of the sample that has been coated, dried and aged by applying the hydrophilic layer coating solution 1 described above. The lithographic printing plate materials 101 to 104 except that the “composite emulsion according to the present invention or comparative emulsion” was added as shown in Table 3 to the image forming layer coating liquids 1 to 4 to which parts by mass of Table 3 were added. The lithographic printing plate materials 201 to 204 were prepared as shown in Table 3 by coating, drying, and aging treatment in the same manner as in the preparation of the above.

<< Preparation of planographic printing plate materials 301-304 >>
The hydrophilic layer coating liquids 1 to 4 are coated, dried and aged as shown in Table 4, and 100 parts by mass of the image forming layer coating liquid 1 is added to a solid content of 20 on the hydrophilic layer of the sample. The image forming layer coating liquids 1 to 4 to which “parts of the composite emulsion according to the present invention or comparative emulsion according to the present invention” adjusted to mass% were added in parts by mass as shown in Table 4 were applied as shown in Table 4. In the same manner as in the production of the lithographic printing plate materials 101 to 104 and 201 to 204, the lithographic printing plate materials 301 to 304 were produced as shown in Table 4 by coating, drying and aging treatment.

(Cutting of lithographic printing plate materials)
The lithographic printing plate material after the aging treatment was cut on a cutting mat so as to have a size of 670 mm × 560 mm using a cutter L-300RP manufactured by NT Corporation.

"Evaluation methods"
Evaluation of [Powder Drops at Cutting] After cutting the lithographic printing plate material, the powder drop at the cutting part on the cutting mat was observed with a loupe (magnification: 10 times). Evaluated "fallen".

◎: The powder fall was not visible with a loupe ○: Fine powder was observed with the loupe △: Fine powder was visually observed x: A large amount of powder was easily observed visually [Print life] And [Blanket stain] evaluation (exposure by infrared laser)
The lithographic printing plate material was wound around an exposure drum and fixed. A laser beam having a wavelength of 830 nm and a spot diameter of about 18 μm was used for exposure, and an image was formed with 2400 dpi (dpi represents the number of dots per 2.54 cm) and 175 lines. The exposed image includes a solid image, a 1 to 99% halftone dot image, a 2400 dpi line and space thin line image, and registration marks for position confirmation at the four corners of the printing plate.

(printing)
Each lithographic printing plate material of K (black), C (cyan), M (magenta), and Y (yellow) is subjected to image exposure, and then a paper: OK top coat using a Lithlon 426 printing machine manufactured by Komori Corporation. (Made by Oji Paper Co., Ltd.), dampening water: Astro Mark 3 (made by Nikken Chemical Laboratories) 2% by mass, ink: TK High Unity Neo ink, indigo, red, yellow (made by Toyo Ink Co., Ltd.) Printing was performed at a printing speed of 9000 sheets / hour. The printing order was K → C → M → Y.

  The exposed lithographic printing plate material was directly attached to the plate cylinder of a printing press, and printing was performed up to 30000 sheets using the same printing conditions and printing sequence as the PS plate.

[Print durability]
Using the halftone dot part of 2% of the 500th printed material as a reference after starting printing, sampling is performed every 2000 printed sheets from the start of printing, and the degree of dot missing is observed with a loupe (magnification: 30 times). “Print durability” was evaluated according to the standard.

◎: 2% halftone dot missing after 30000 sheets ○: 2% halftone dot missing after 30000 sheets △: 2% halftone dot missing occurs from 20000 to less than 30000 sheets ×: Less than 20000 sheets 2% halftone dot missing occurs [Blanket stain]
The reflection density (D2) of the K (black) blanket after printing from the end of printing 5000 sheets was measured using X-Rite 520 and X-Rite 520, and the Status-T visual density was measured. A density difference (D2−D1) from the reflection density (D1) was obtained, and “blanket stain” was evaluated according to the following criteria.

◎: Less than 0.05 ○: Less than 0.08 Δ: 0.08 or more and less than 0.20 ×: 0.20 or more The results are shown in Table 2, Table 3, and Table 4.

Mobile 8010: Styrene-acrylic acid ester copolymer / colloidal silica composite emulsion, average particle size of 80 nm (photon correlation method), (manufactured by Nichigo Mobile)
Mobile 8020: Acrylic ester copolymer / colloidal silica composite emulsion, average particle size of 100 nm (photon correlation method), (manufactured by Nichigo Mobile Co., Ltd.)
Mobile 880: Styrene-acrylic acid ester copolymer emulsion, average particle diameter 75 nm (photon correlation method), (manufactured by Nichigo Mobile)
As is apparent from Table 2, in the case of the present invention, it is found that the powder is excellent in powder removal at the time of cutting, and further, it is excellent in printing durability and blanket contamination.

Mobile 8030: Composite emulsion of acrylate copolymer and colloidal silica, average particle diameter 80 nm (photon correlation method), (manufactured by Nichigo Mobile Co., Ltd.)
Mobile 8055A: Styrene-acrylic acid ester copolymer / colloidal silica composite emulsion, average particle size 80 nm (photon correlation method), (manufactured by Nichigo Mobile)
Mobile 749E: Styrene-acrylic acid ester copolymer emulsion (Nichigo Movinyl Co., Ltd.)
As is apparent from Table 3, in the case of the present invention, it is found that the powder is excellent at the time of cutting, and further, the printing durability and the blanket stain are excellent.

  As can be seen from Table 4, in the case of the present invention, it is found that the powder is excellent at the time of cutting, and further, the printing durability and the blanket stain are excellent.

  As is apparent from Tables 2 to 4, according to the present invention, the lithographic printing plate material significantly reduces the process contamination due to powder falling when cutting to a predetermined size during the production of the lithographic printing plate material without adversely affecting the printing performance. Can be provided.

  Furthermore, according to the present invention, process contamination due to powder falling when cutting to a predetermined size during production of a lithographic printing plate material, contamination of the printing press when the lithographic printing plate material is attached to a printing press, and an operator's lithographic printing plate It can be seen that a lithographic printing plate material can be provided that significantly reduces contamination during material handling.

Claims (4)

In the lithographic printing plate material having a hydrophilic layer and an image forming layer in this order from the support side on the support, the hydrophilic layer or the image forming layer contains a composite emulsion comprising a thermoplastic resin and inorganic particles. A planographic printing plate material. 2. The lithographic printing plate material according to claim 1, wherein the support surface is an anodized film of aluminum. The lithographic printing plate material according to claim 1 or 2, wherein the hydrophilic layer contains at least colloidal silica. The composite emulsion comprising the thermoplastic resin and inorganic particles comprises at least a styrene / acrylic copolymer resin or an acrylic copolymer resin, and colloidal silica. Lithographic printing plate material.