JP2007276196A - Lithographic printing plate material and printing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lithographic printing plate material for a CTP system which is excellent in on-press developability and also in plate wear resistance, scumming in a long-time storage and flaw smudging in a non-image area, and a printing method. <P>SOLUTION: In the lithographic printing plate material which has on a base a hydrophilic layer containing a photothermal conversion agent and a thermal image forming layer in this sequence from the base side, spherical cellulose particles of which the average particle diameter is 3-20 μm are contained in the hydrophilic layer. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a lithographic printing plate material (hereinafter also simply referred to as a printing plate material) and a printing method, and more particularly to a lithographic printing plate material and a printing method used in a computer-to-plate (hereinafter referred to as CTP) system.

  Currently, in the field of printing, printing by the CTP method has been performed with the digitization of print image data, but 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 printing plate material for a CTP system having the following printability.

  In particular, in recent years, it has direct imaging (hereinafter referred to as DI) performance that does not require development processing with a special agent, and can be applied to a printing press having this function, and has the same usability as the PS plate. Therefore, there is a need for a general-purpose processless plate.

  An infrared laser recording system having a wavelength of near infrared to infrared is mainly used for image formation of a thermal processless plate. Thermal processless plates that can form images by this method are broadly divided into ablation types and development types on thermal fusion image layer machines.

  Examples of the ablation type include those described in JP-A-8-507727, JP-A-6-186750, JP-A-6-199064, JP-A-7-314934, JP-A-10-58636, and JP-A-10-244773. Can be mentioned.

  In these, for example, a hydrophilic layer and a lipophilic layer are laminated on a base material with either layer as a surface layer. If the surface layer is a hydrophilic layer, it is possible to form an image portion by exposing it like an image, ablating the hydrophilic layer and removing it like an image to expose the lipophilic layer. However, contamination of the inside of the exposure apparatus due to the ablated surface scattered matter becomes a problem, so that a special suction device may be required for the exposure apparatus, and the versatility of the exposure apparatus is low.

  On the other hand, development of a printing plate material that can form an image without causing ablation and does not require a developing process or a wiping process with a special developer is also underway. For example, a binder of thermoplastic fine particles and a water-soluble polymer compound is used for a thermal image forming layer as disclosed in Japanese Patent Nos. 2938397, 2938397, 9-123387, 9-123388. CTP printing plate materials that can be developed using dampening water or ink on a printing press. These on-press developable printing plate materials provide sharp dot shapes and high-definition images, and do not require a development process after exposure, and are excellent in environmental suitability.

  However, these printing plate materials have a problem that the printing durability is insufficient because the film strength of the hydrophilic layer and the image forming layer itself is weak. In response to these problems, a reactive thermoplastic resin is added to the image forming layer to improve it (for example, see Patent Documents 1 and 2).

  When the reactive thermoplastic resin is added, developability deteriorates and stains and scratches on non-image areas are likely to occur, and there is a strong demand for the development of a printing plate that satisfies the above requirements.

  Furthermore, as a printing plate material that can be developed on-press without causing ablation, it is also known that a lithographic printing plate precursor having an image recording layer containing a microcapsule encapsulating a polymerizable compound can be developed on-press (for example, , See Patent Document 3).

  An on-press developable lithographic printing plate precursor having a photosensitive layer containing an infrared absorber, a radical polymerization initiator, and a polymerizable compound on a support is known (see, for example, Patent Document 4). .

In order to achieve both on-press developability, stain and printing durability of the printing plate, it is disclosed that an undercoat layer using a specific water-soluble resin is provided between the support and the image recording layer. However, it was found that the printing durability was not sufficient in the case of printing using powder, and because the polymerizable compound was used, developability and stains during long-term storage deteriorated.
JP 2005-297233 A JP 2005-305690 A JP 2001-277740 A JP 2002-365789 A

  An object of the present invention is to provide a lithographic printing plate material for CTP method and a printing method which are excellent in on-press development property, excellent in printing durability, ground stains during long-term storage, and scratches in non-image areas. is there.

  The above object of the present invention is achieved by the following configurations.

  1. In a lithographic printing plate material having a hydrophilic layer containing a photothermal conversion agent and a thermal image-forming layer in this order from the substrate side on the substrate, spherical cellulose particles having an average particle diameter of 3 to 20 μm are formed on the hydrophilic layer. A lithographic printing plate material comprising:

  2. In a lithographic printing plate material having a hydrophilic layer containing a photothermal conversion agent and a thermal image forming layer in this order from the substrate side on the substrate, spherical cellulose having an average particle size of 1 to 10 μm in the thermal image forming layer A lithographic printing plate material comprising particles.

  3. 3. The lithographic printing plate material as described in 1 or 2 above, wherein the cellulose particles are porous.

  4). 4. The lithographic printing plate material according to any one of 1 to 3, wherein the heat-sensitive image forming layer is a layer that can be developed on-press.

  5. The lithographic printing plate material according to any one of 1 to 4 above is image-exposed with a laser beam, and then printed on a lithographic printing machine by developing with dampening water or dampening water and printing ink. How to print.

  According to the above constitution of the present invention, the lithographic printing plate for the CTP method has good ink inking property, excellent on-press developability, good anti-scumming property, excellent printability, excellent printing durability and scratch resistance. Material can be provided.

  Hereinafter, the present invention will be described in more detail.

  The present invention relates to a lithographic printing plate material having a hydrophilic layer containing a photothermal conversion agent and a heat-sensitive image forming layer in this order from the substrate side on the base material, and the hydrophilic layer or the heat-sensitive image forming layer has a spherical shape. It contains cellulose particles.

  In the present invention, by containing spherical cellulose particles having a specific average particle diameter in the hydrophilic layer or the heat-sensitive image forming layer, the ink depositing property is excellent, the on-press developability is excellent, and the anti-staining property is obtained. A lithographic printing plate material for the CTP system which is excellent and excellent in printability, excellent in printing durability and scratch resistance can be provided.

(Spherical cellulose particles)
In the present invention, it is essential to contain spherical cellulose particles having a specific average particle size in the hydrophilic layer and / or the image forming layer. Due to the spherical and specific average particle size, a matte effect and slipperiness due to surface irregularities are developed, and scratch resistance and printing durability are improved. Spherical cellulose has a spherical shape and hydrophilicity, which suppresses deterioration of soil. In particular, porous materials have good performance.

  As said spherical cellulose particle in connection with this invention, what consists of a cellulose or a cellulose ester is preferable. Here, as the cellulose ester, for example, cellulose esters such as cellulose triacetate, cellulose tripropionate, cellulose tributyrate, and cellulose trinitrate; cellulose mixtures such as acetic acid / cellulose butyrate, acetic acid / propionic acid cellulose, and propionic acid / butyric acid cellulose Esters: Cellulose partial esters such as cellulose diacetate, cellulose dinitrate, cellulose dipropionate, cellulose dibutyrate, cellulose monoacetate, and cellulose mononitrate, and intermediate esters thereof. Of these, those composed of cellulose or cellulose triacetate are particularly preferred.

  The average particle size of the spherical cellulose particles must be 3 to 20 μm when employed in the hydrophilic layer. Preferably it is 3-10 micrometers, More preferably, it is 3-7 micrometers. If it is less than 3 μm, the mat effect and sliding effect will not be exhibited, and the scratch resistance and printing durability will deteriorate. On the other hand, if the thickness exceeds 20 μm, not only the hydrophilic layer cannot be retained, but also background stains are deteriorated, which is not preferable. On the other hand, when it is used for the image forming layer, it is necessary to be 1 to 10 μm. Preferably it is 1-8 micrometers, More preferably, it is 1-5 micrometers. When the thickness is less than 1 μm, the mat effect and the slip effect are not exhibited like the hydrophilic layer, and the scratch resistance and printing durability are deteriorated. On the other hand, if it exceeds 10 μm, it cannot be held in the image forming layer, and the printing durability is deteriorated.

  The average particle diameter here is an average value of primary particle diameters. The primary particle size is obtained by photographing the metal oxide particles having the range of Mohs hardness according to the present invention with an electron microscope, measuring the longest side and the shortest side of the metal oxide particles in the projection, and calculating the average value as the average particle size. Is the value calculated as The average particle diameter is a value obtained by measuring 100 particles having a particle diameter in the range of 0.12 μm or more and 0.4 μm, and calculating a number average value.

  The spherical cellulose particles can be used alone or in combination of two or more.

  The content of the spherical cellulose particles is preferably 0.1 to 50% by mass, particularly 1 to 20% by mass, and more preferably 3 to 10% by mass in the hydrophilic layer. If it is less than 0.1%, the effect of the present invention cannot be exhibited. On the other hand, if it exceeds 50%, the film forming layer of the hydrophilic layer is lowered and the effect of the present invention cannot be exhibited.

  On the other hand, about an image forming layer, it is preferable to mix | blend 0.1-20 mass% in an image forming layer, especially 0.5-10 mass%, and also 1-5 mass%. If it is less than 0.1%, the effect of the present invention cannot be exhibited. On the other hand, if it exceeds 20%, the film forming layer of the image forming layer is lowered and the effect of the present invention cannot be exhibited.

For the production method of the spherical cellulose particles, a production method such as JP-A-5-200288 can be referred to. For example,
(I) A viscose liquid and a surfactant are added to a dispersion medium composed of a water-immiscible liquid to produce a water / oil-type viscose emulsion liquid. Separately, a dispersion composed of a water-immiscible liquid A viscose coagulation liquid is added to the medium to prepare a water / oil type viscose coagulation liquid emulsion, and both emulsions are mixed and reacted with each other to form spherical cellulose fine particles having an average particle size of 15 μm or less. Method,
(II) A viscose liquid and a surfactant are added to a dispersion medium composed of a water-immiscible liquid to prepare a water / oil type viscose emulsion, and an acidic gas is blown into the viscose emulsion, A method of reacting a viscose emulsion and the acidic gas to form spherical cellulose fine particles having an average particle size of 15 μm or less,
(III) A viscose liquid and a surfactant are added to a dispersion medium composed of a water-immiscible liquid to prepare a water / oil type viscose emulsion. There is a method in which spherical cellulose fine particles having an average particle size of 15 μm or less are formed by dropping them into a viscose coagulating liquid or a mixed liquid of a viscose coagulating liquid and a surfactant.

<Hydrophilic layer>
(Photothermal conversion agent)
In the present invention, the hydrophilic layer and the image forming layer realize high sensitivity by containing the following photothermal conversion material. In particular, the following metal oxide is preferably added to the hydrophilic layer as a photothermal conversion material.

As the photothermal conversion agent, a material that is black in the visible light region, or a material that is conductive or is a semiconductor can be used. Examples of the former include black iron oxide (Fe ₃ O ₄ ) and black mixed metal oxides containing two or more of the aforementioned metals. Examples of the latter include Sb-doped SnO2 (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. These average particle diameters are 0.5 μm or less, preferably 100 nm or less, and more preferably 50 nm or less.

  Among these photothermal conversion materials, black composite metal oxides containing two or more metals are more preferable materials.

  Specifically, it is a composite metal oxide composed of two or more metals selected from Al, Ti, Cr, Mn, Fe, Co, Ni, Cu, Zn, Sb, and Ba. 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 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-8-273393 in order to reduce the elution of hexavalent chromium. These composite metal oxides are colored with respect to the amount added, that is, they have good photothermal conversion efficiency.

  These composite metal oxides preferably have an average primary particle size of 1 μm or less, and more preferably have an average primary particle size 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. However, the photothermal conversion ability with respect to the addition amount is greatly affected by the degree of dispersion of the particles, and the better the dispersion, the better. Therefore, it is preferable to disperse these composite metal oxide particles by a known method separately before adding them to the layer coating solution to prepare a dispersion (paste). An average primary particle size of less than 0.01 is not preferable because dispersion becomes difficult. A dispersing agent can be appropriately used for the dispersion. The addition amount of the dispersant is preferably 0.01 to 5% by mass, and more preferably 0.1 to 2% by mass with respect to the composite metal oxide particles.

  The addition amount of these composite metal oxides is 20% or more and less than 40%, more preferably 25% or more and less than 39%, more preferably 25% or more and less than 30%, based on the total solid content of the hydrophilic layer. Range. When the addition amount is less than 20%, sufficient sensitivity cannot be obtained, and when it is 40% or more, ablation residue due to ablation occurs.

  In the present invention, the following infrared absorbing dye can be added as a photothermal conversion material to the hydrophilic layer and the image forming layer. General infrared absorbing dyes such as cyanine dyes, croconium dyes, polymethine dyes, azurenium dyes, squalium dyes, thiopyrylium dyes, naphthoquinone dyes, anthraquinone dyes, organic compounds such as phthalocyanine dyes and naphthalocyanine dyes , Azo-based, thioamide-based, dithiol-based, and indoaniline-based organometallic complexes. Specifically, JP-A-63-139191, JP-A-64-33547, JP-A-1-160683, JP-A-1-280750, JP-A-1-293342, JP-A-2-2074, Kaihei 3-26593, JP-A-3-30991, JP-A-3-34891, JP-A-3-36093, JP-A-3-36094, JP-A-3-36095, JP-A-3-42281, JP-A-3-42281 Examples thereof include compounds described in JP-A-3-97589, JP-A-3-103476, and the like. These can be used alone or in combination of two or more.

  The addition amount of these infrared absorbing dyes is 0.1% or more and less than 10%, more preferably 0.3% or more and less than 7%, more preferably 0.5%, based on the total solid content of the image forming layer. The range is less than 6%. If the addition amount deviates from this, as described above, if the addition amount is less than 0.1%, sufficient sensitivity cannot be obtained, and if it is 10% or more, ablation residue due to ablation occurs.

  The hydrophilic layer according to the present invention may contain a material for forming the following hydrophilic matrix structure in addition to the photothermal conversion agent and the polymer compound.

  The material for forming the hydrophilic matrix is preferably a metal oxide other than those described above, and more preferably contains metal oxide particles.

  Examples of the metal oxide include colloidal silica, alumina sol, titania sol, and other metal oxide sols. The metal oxide may have any shape such as a spherical shape, a feather shape, and the like. Is preferably 3 to 100 nm, and several kinds of metal oxide particles having different average particle diameters may be used in combination. Further, the surface of the particles may be subjected to a surface treatment.

  The metal oxide 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.

  In the present invention, colloidal silica is particularly preferably used among the above. Colloidal silica has the advantage of high film-forming properties even under relatively low temperature drying conditions, and can provide good strength.

  As colloidal silica, necklace-like colloidal silica and colloidal silica having an average particle size of 20 nm or less are preferable, and alkaline colloidal silica is preferable.

  Necklace-shaped colloidal silica is a general term for the water dispersion diameter of spherical silica whose primary particle diameter is on the order of nm. Necklace-shaped colloidal silica means “pearl necklace-shaped” colloidal silica in which spherical colloidal silica having a primary particle diameter of 10 to 50 nm is bonded to a length of 50 to 400 nm.

  A pearl necklace shape (that is, a pearl necklace shape) means that an image in a state in which silica particles of colloidal silica are joined together and connected is shaped like a pearl necklace. The bond between the silica particles constituting the necklace-shaped colloidal silica is presumed to be —Si—O—Si— in which —SiOH groups present on the surface of the silica particles are dehydrated. Specific examples of the colloidal silica in the form of necklace include “Snowtex-PS” series manufactured by Nissan Chemical Industries, Ltd.

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

  Further, as described above, it is particularly preferable to use alkaline colloidal silica because the alkaline substance has a high effect of suppressing the occurrence of soiling in the colloidal silica.

  Alkaline colloidal silica with an average particle size in this range Nissan Chemical's “Snowtex 20 (particle size 10-20 nm)”, “Snowtex-30 (particle system 10-20 nm)”, “Snowtex-40 (particles) "Snowtex-N (particle diameter 10-20 nm)", "Snowtex-S (particle diameter 8-11 nm)", "Snowtex-XS (particle diameter 4-6 nm)". It is done.

  Colloidal silica having an average particle size of 20 nm or less is particularly preferred because it can be further improved in strength while maintaining the porosity of the layer when used in combination with the aforementioned necklace-shaped colloidal silica.

  The ratio of colloidal silica / necklace-shaped colloidal silica having an average particle diameter of 20 nm or less is preferably 95/5 to 5/95, more preferably 70/30 to 20/80, and still more preferably 60/40 to 30/70.

  As a porous material for the hydrophilic matrix of the hydrophilic layer according to the present invention, porous metal oxide particles having an average particle diameter of less than 1 μm can be contained. As the porous metal oxide particles, porous silica, porous aluminosilicate particles, or zeolite particles described later can be preferably used.

  The 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. In the dry method, silicon tetrachloride is burned together with hydrogen and oxygen to obtain silica.

  These particles can control the porosity and the average particle diameter by adjusting the production conditions. The porous silica particles are particularly preferably those obtained from a wet gel. The porous aluminosilicate particles are produced, for example, by the method described in JP-A-10-71764.

  That is, it is an amorphous composite particle synthesized by hydrolysis using aluminum alkoxide and silicon alkoxide as main components. The ratio of alumina to silica in the particles can be synthesized in the range of 1: 4 to 4: 1. In addition, particles produced by adding other metal alkoxides at the time of production as composite particles having three or more components can also be used in the present invention. These composite particles can also control the porosity and average particle diameter by adjusting the production conditions.

  The porosity of the particles is preferably 0.5 ml / g or more in terms of pore volume, more preferably 0.8 ml / g or more, and further preferably 1.0 to 2.5 ml / g or less. preferable.

  Zeolite can also be used as the porous material of the present invention. Zeolite is a crystalline aluminosilicate and is a porous body having regular three-dimensional network voids having a pore diameter of 0.3 to 1 nm.

  The hydrophilic layer according to the present invention can contain mineral particles. Mineral particles include clay minerals such as kaolinite, halloysite, talc, smectite (montmorillonite, beidellite, hectorite, sabonite, etc.), vermiculite, mica (mica), chlorite, hydrotalcite, layered polysilicate (kanemite, Layered mineral particles such as macatite, ialite, magadiite, kenyaite, etc.).

  Among them, it is considered that the higher the charge density of the unit layer (unit layer), the higher the polarity and the higher the hydrophilicity. The charge density is preferably 0.25 or more, more preferably 0.6 or more. Examples of the layered mineral having such a charge density include smectite (charge density 0.25 to 0.6; negative charge), vermiculite (charge density 0.6 to 0.9; negative charge) and the like. In particular, synthetic fluoromica is preferable because it can be obtained with stable quality such as particle size.

  Among the synthetic fluorine mica, those that are swellable are preferable, and those that are free swell are more preferable.

  As for the size of the layered mineral particles, the average particle size (maximum length of the particles) is less than 1 μm, and the average aspect ratio is contained in the layer (including the case of undergoing the swelling process and dispersion peeling process). Is preferably 50 or more. When the particle size is in the above range, the continuity and flexibility in the planar direction, which are the characteristics of the thin layered particles, are imparted to the coating film, and it is difficult for cracks to occur, and a tough coating film can be obtained in a dry state. Moreover, in the coating liquid containing many particulate matters, sedimentation of particulate matter can be suppressed by the thickening effect of the layered clay mineral. When the particle diameter is larger than the above range, the coating film may be non-uniform, and the strength may be locally reduced.

  The content of the layered mineral particles is preferably from 0.1 to 10% by mass, and more preferably from 0.1 to 3% by mass, based on the entire layer. In particular, swellable synthetic fluorinated mica and smectite are preferable because they are effective even when added in a small amount. The layered mineral particles may be added as a powder to the coating solution, but in order to obtain a good degree of dispersion even with a simple preparation method (no need for a dispersion step such as media dispersion), the layered mineral particles are used alone. After the gel swollen in water is prepared, it is preferably added to the coating solution.

(Other materials)
A silicate aqueous solution can also be used as another additive material in the hydrophilic layer according to the present invention. Alkali metal silicates such as silicate Na, silicate K, and silicate Li are preferred, and the SiO ₂ / M ₂ O ratio is in a range where the pH of the entire coating solution does not exceed 13 when silicate is added. It is preferable to select such that the inorganic particles are not dissolved.

  Further, an inorganic polymer or an organic-inorganic hybrid polymer using a metal alkoxide by a so-called sol-gel method can also be used. The formation of an inorganic polymer or an organic-inorganic hybrid polymer by the sol-gel method is described in, for example, “Application of the sol-gel method” (Sakuo Sakuo / Published by Agne Jofusha) or cited in this book. Known methods described in the published literature can be used.

  The hydrophilic layer may contain a water-soluble resin or a water-dispersible resin. Such resins include polysaccharides, polyethylene oxide, polypropylene oxide, polyvinyl alcohol, polyethylene glycol (PEG), polyvinyl ether, styrene-butadiene copolymer, conjugated diene polymer latex of methyl methacrylate-butadiene copolymer, Resins such as acrylic polymer latex, vinyl polymer latex, polyacrylamide, and polyvinylpyrrolidone can be used.

  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.

  The hydrophilic layer coating solution of the present invention may contain a water-soluble surfactant for the purpose of improving coating properties. 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 of 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 during 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 drying with the amount of the hydrophilic layer is preferably ^{0.1~20g / m 2, 0.5~15g / m} 2 , more preferably still, 1 to 10 g / m ² is particularly preferred.

(Spherical silica particles)
In the present invention, the hydrophilic layer preferably contains silica particles having an average particle diameter of 4.0 to 8.0 μm and a CV value of 1 to 10%. By containing spherical silica particles that have both the above average particle size and CV value, the surface irregularities of the hydrophilic layer and the image forming layer can be controlled, and when printing paper using powder or paper with a lot of paper dust is used This is effective in preventing wear of the image forming layer with respect to the foreign matter and improving the scratch resistance and visible image quality of the non-image area.

  The CV value of the present invention is a value called a variation count, and is an index representing relative dispersion.

  A smaller value means less dispersion of the average particle size distribution. Since the standard deviation is affected by the scale, it cannot be compared with each other. However, since the coefficient of variation excludes the influence of the scale from the standard deviation, the degree of dispersion can be compared with each other even if the unit is different.

  Since the fluctuation of the measured value at the time of repeated measurement has a normal distribution, the coefficient of variation is calculated from the average value and the standard deviation.

CV (%) = (standard deviation of particle size / average particle size) × 100
The average particle size is an average value of the primary particle size. The primary particle size is obtained by calibrating the Coulter counter using standard particles whose particle size is known, and using the calibrated Coulter counter, The diameter distribution (CV value) is obtained.

  The CV value is required to be 1 to 10% from the viewpoint of printability and scratch resistance, but 1 to 5% is particularly preferable.

  The average particle size of the spherical silica particles according to the present invention is preferably 4.0 to 8.0 μm from the viewpoint of scratch resistance and printing durability. If it is less than 4.0 μm, the surface unevenness becomes small, and scratch resistance and printing durability deteriorate, which is not preferable. On the other hand, if it is larger than 8.0 μm, the ink is liable to adhere and the stain resistance is deteriorated, which is not preferable.

  In the present invention, the silica particles contained in the hydrophilic layer are preferably 3 to 40% by mass, particularly 5 to 25% by mass from the viewpoint of film strength, scratch resistance, and printability with respect to the total solid content of the hydrophilic layer. % Is preferred.

As a form of the present invention, the hydrophilic layer may be divided into two layers (upper layer and lower layer). Since the performance can be partially separated by dividing the hydrophilic layer into two layers, it is preferable.
The same material can be used for the upper and lower layers, but the lower layer has less advantage of being porous. The content of the porous material of the hydrophilic matrix is preferably smaller than that of the hydrophilic layer. Along with this, the spherical silica particles and particles having the following average particle diameter of 1 to 12 μm can be retained, so it is effective to add more particles to the lower layer. On the other hand, since the upper layer is required to be porous, it is preferable to adopt a method opposite to that of the lower layer.

(Spherical particles having an average particle size of 3.0 to 4.0 μm)
In this invention, it is preferable to contain the particle | grains coat | covered with the inorganic particle or inorganic material whose average particle diameter is 1-12 micrometers as particle | grains other than the above. In particular, the average particle size is preferably 2 to 10 μm, and more preferably 3 to 8 μm.

  Among these, 3 to 4 μm spherical particles are used in combination with the spherical silica particles, thereby improving printing durability and scratch resistance of non-image areas. The inventors estimate that the performance is improved by arranging 3 to 4 μm spherical particles in the exposed portion of the image layer around the spherical silica particles. The above effect can be achieved by increasing the amount of spherical silica particles. However, it is estimated that particles having different average particle diameters, particularly spherical particles having a diameter of 3 to 4 μm, can be sufficiently arranged in the vacant space, and thus the effect is better.

The addition amount of the particles having an average particle diameter of 1 to 12 μm is preferably 0.5 to 50% by mass, more preferably 3 to 30% by mass based on the entire hydrophilic layer.
The composition and structure of the particles may be porous, nonporous, organic resin particles, or inorganic fine particles, and the inorganic filler may be silica, alumina, zirconia, titania, carbon black, graphite, TiO ₂ , BaSO _4. ZnS, MgCO ₃ , CaCO ₃ , ZnO, CaO, WS ₂ , MoS ₂ , MgO, SnO ₂ , Al ₂ O ₃ , α-Fe ₂ O ₃ , α-FeOOH, SiC, CeO ₂ , BN, SiN, MoC , BC, WC, titanium carbide, corundum, artificial diamond, garnet, garnet, silica, triboli, diatomaceous earth, dolomite, etc. Organic fillers include polyethylene fine particles, fluororesin particles, guanamine resin particles, acrylic resin particles, silicone resin Examples thereof include particles and melamine resin particles.

  Examples of the inorganic filler include particles obtained by coating a core of organic particles such as PMMA, polystyrene, and melamine with inorganic particles that are smaller than the core particles. The average particle size of the inorganic particles is preferably about 1/10 to 1/100 of the core particles. As the inorganic particles, similarly known metal oxide particles such as silica, alumina, titania, zirconia can be used. As the coating method, various known methods can be used, but the core material particles and the coating material particles are collided at high speed in the air like a hybridizer to cause the coating material particles to bite into the surface of the core material particles. A dry coating method of fixing and coating can be preferably used.

  In the present invention, any filler that satisfies the scope of the present invention can exert its effect without any particular limitation. In particular, in order to suppress sedimentation in the coating solution, porous silica particles, porous aluminosilicate particles, etc. It is preferable to use a porous inorganic filler and a porous inorganic filler.

(Thermal image forming layer)
The heat-sensitive image forming layer is a layer that can form an image by heating, and is a thermoplastic compound such as a heat-fusible material or heat-fusible material, or a material that changes from hydrophilic to hydrophobic by heating (hydrophobic precursor) )including. The heating method is a method using heat generated by exposure to actinic rays, and an image forming method using heat generated by laser light exposure is particularly preferable.

  The heat-sensitive image forming layer according to the present invention is highly effective in the case of image formation that can be developed on-press.

  On-press development means that after printing plate material is image-exposed, it can be developed with lithographic dampening water or dampening water and printing ink on the printing press without any particular development process, and can be directly transferred to the printing process. It means that it can be transferred.

  The heat-sensitive image forming layer of the present invention preferably contains a thermoplastic compound as thermoplastic particles in the form of particles.

  That is, it is preferable to use a heat-meltable material or a heat-fusible material in the form of particles as heat-meltable particles or heat-fusible particles.

  Moreover, as one of the preferable aspects of the heat-sensitive image forming layer according to the present invention, an aspect in which the heat-sensitive image forming layer contains a hydrophobized precursor is also a preferable aspect.

  As the hydrophobizing precursor, a polymer that changes from hydrophilicity (water-soluble or water-swellable) to hydrophobicity by heat can be used. Specific examples include polymers containing aryl diazosulfonate units disclosed in JP-A-2000-56449.

  The heat-meltable particles are particles made of a material that has a low viscosity when melted among thermoplastic materials and is generally classified as a wax. 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. In addition, since these materials have lubricity, damage when a shearing force is applied to the surface of the printing plate material is reduced, and resistance to printing stains due to scratches or the like is improved.

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

  Moreover, the composition of the inside and the surface layer of the heat-meltable particles may be continuously changed, 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.

  In the heat-sensitive image forming layer of the present invention, it is particularly preferable that the heat-meltable particles are contained in a microcapsule form.

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

  Examples of the heat-fusible particles used in the present invention include thermoplastic hydrophobic polymer particles, and there is no specific upper limit for the softening temperature of the polymer particles, but the temperature is the same as that of the polymer particles. It is preferable that the temperature is lower than the decomposition temperature. 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 polymer polymer fine particles may be composed of a polymer polymer polymerized by any known method such as emulsion polymerization, suspension polymerization, solution polymerization, and gas phase polymerization. As a method of microparticulating a polymer polymer polymerized by a solution polymerization method or a gas phase polymerization method, a method of spraying a solution in an organic solvent of the polymer polymer into an inert gas and drying to form particles, Examples thereof include a method in which a high molecular weight polymer is dissolved in a water-immiscible organic solvent, this solution is dispersed in water or an aqueous medium, and the organic solvent is distilled off to form fine particles. In any of the methods, a surfactant, such as sodium lauryl sulfate, sodium dodecylbenzenesulfonate, polyethylene glycol, or a water-soluble resin, such as polyvinyl alcohol, is used as a dispersant or stabilizer in polymerization or micronization as necessary. May be used.

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

  Further, the composition of the heat fusible 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.

  In the heat-sensitive image forming layer of the present invention, it is particularly preferable that the heat-fusible particles are contained in a microencapsulated form.

  Examples of the microcapsule include microcapsules enclosing a hydrophobic material described in JP-A-2002-2135 and JP-A-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 thickness of the wall of the microcapsule is preferably 1/100 to 1/5 of the diameter, and more preferably 1/50 to 1/10.

  The content of the microcapsule is 5 to 100% by mass of the entire heat-sensitive image forming layer, preferably 20 to 95% by mass, and more preferably 40 to 90% by mass.

  Known materials and methods can be used as the material for the wall of the microcapsule and the method for producing the microcapsule. For example, known materials and methods described in “New Microcapsules, Production Method, Properties, and Applications” (written by Tamotsu Kondo, Masumi Koishi / Published by Sankyo Publishing Co., Ltd.) or cited references are used. be able to.

  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.

  The heat-sensitive image forming layer according to the present invention can further contain a water-soluble material. By including the water-soluble material, when the thermal image forming layer in the unexposed area is removed with dampening water or ink on the printing press, the removability can be improved.

  As the water-soluble material, the water-soluble resins mentioned as materials that can be contained in the hydrophilic layer can also be used. The water-soluble resin that can be used in the heat-sensitive image forming layer is selected from hydrophilic natural polymers and synthetic polymers.

  Specific examples of water-soluble resins preferably used in the present invention include natural gums, gum arabic, water-soluble soybean polysaccharides, fiber derivatives (eg, carboxymethyl cellulose, carboxyethyl cellulose, methyl cellulose, etc.), and modifications thereof. In the case of synthetic polymers such as body, white dextrin, pullulan, enzymatically degraded etherified dextrin, polyvinyl alcohol (preferably having a saponification degree of 70 mol% or more), polyacrylic acid, its alkali metal salt or amine salt, and polyacrylic acid Polymer, alkali metal salt or amine salt thereof, polymethacrylic acid, alkali metal salt or amine salt thereof, vinyl alcohol / acrylic acid copolymer and alkali metal salt or amine salt thereof, polyacrylamide, copolymer thereof, polyhydroxy Ethyl acrylate, Polyvinyl Lupyrrolidone, its copolymer, polyvinyl methyl ether, vinyl methyl ether / maleic anhydride copolymer, poly-2-acrylamido-2-methyl-1-propanesulfonic acid, alkali metal salt or amine salt thereof, poly-2 -Acrylamido-2-methyl-1-propanesulfonic acid copolymer, its alkali metal salt or amine salt. Moreover, these can also be used in mixture of 2 or more types according to the objective. However, the present invention is not limited to these examples.

  The content of the water-soluble resin in the heat-sensitive image forming layer is preferably 1 to 50% by mass, and more preferably 2 to 30% by mass based on the entire layer.

(Other materials that can be included in the thermal image forming layer)
The thermal image forming layer used in the present invention may further contain the following materials.

  In the present invention, it is a preferred embodiment that the thermal image forming layer contains an infrared absorbing dye.

  When used in combination with the metal oxide particles, the film strength of the thermal image forming layer can be further improved, and the printing durability using powder and the resistance to foreign matters when using paper with a lot of paper dust, etc. It can be improved further.

  Infrared absorbing dyes that can be used in the present invention include general infrared absorbing dyes such as cyanine dyes, croconium dyes, polymethine dyes, azurenium dyes, squalium dyes, thiopyrylium dyes, naphthoquinone dyes, anthraquinones. And organic compounds such as phthalocyanines, phthalocyanine-based, naphthalocyanine-based, azo-based, thioamide-based, dithiol-based, and indoaniline-based organometallic complexes. Specifically, JP-A-63-139191, JP-A-64-33547, JP-A-1-160683, JP-A-1-280750, JP-A-1-293342, JP-A-2-2074, Kaihei 3-26593, JP-A-3-30991, JP-A-3-34891, JP-A-3-36093, JP-A-3-36094, JP-A-3-36095, JP-A-3-42281, JP-A-3-42281 Examples thereof include compounds described in JP-A-3-97589, JP-A-3-103476, and the like. These can be used alone or in combination of two or more.

  The addition amount of these infrared absorbing dyes is preferably 0.1% by mass or more and less than 10% by mass, and preferably 0.3% by mass or more and less than 7% by mass with respect to the total solid content of the image forming layer in terms of preventing ablation. More preferably, it is the range of 0.5 mass% or more and less than 6 mass%.

The amount per the image formation layer is preferably 0.01-5 g / m ^2, more preferably from 0.1 to 3 g / m ^2, particularly preferably from 0.2 to 2 g / m ^2.

(Protective layer)
A protective layer may be provided on the thermal image forming layer.

  As a material used for the protective layer, the above-mentioned water-soluble resin can be preferably used.

  Further, hydrophilic overcoat layers described in JP-A Nos. 2002-19318 and 2002-86948 can also be preferably used.

The amount per the protective layer is 0.01 to 10 g / m ^2, preferably from 0.1 to 3 g / m ^2, more preferably from 0.2 to 2 g / m ^2.

(Base material)
As a base material, the well-known material used as a board | substrate of a printing plate can be used. For example, a metal plate, a plastic film, paper treated with a polyolefin, a composite base material obtained by appropriately bonding the above materials, and the like can be given. The thickness of the base material 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. Moreover, it can also use combining an anodizing process and the said immersion or application | coating process. Moreover, the aluminum plate roughened by the well-known method can also be used.

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

  Among these, polyesters such as PET and PEN are preferable from the viewpoint of handling suitability, and PET is particularly preferable.

  PET is composed of terephthalic acid and ethylene glycol, and PEN is composed of naphthalene dicarboxylic acid and ethylene glycol, which can be polymerized by combining them in the presence of a catalyst under suitable reaction conditions. At this time, you may mix an appropriate 1 type, or 2 or more types of 3rd component.

  The suitable third component may be any compound having a divalent ester-forming functional group. Examples of the dicarboxylic acid include the following.

  For example, isophthalic acid, phthalic acid, 2,6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, diphenylsulfone dicarboxylic acid, diphenyl ether dicarboxylic acid, diphenylethane dicarboxylic acid, cyclohexane dicarboxylic acid, diphenyl dicarboxylic acid, diphenyl thioether dicarboxylic acid, Examples thereof include diphenyl ketone dicarboxylic acid and phenyl indane dicarboxylic acid.

  Examples of glycols include ethylene glycol, propylene glycol, tetramethylene glycol, cyclohexanedimethanol, 2,2-bis (4-hydroxyphenyl) propane, 2,2-bis (4-hydroxyethoxyphenyl) propane, bis (4-Hydroxyphenyl) sulfone, bisphenol full orange hydroxyethyl ether, diethylene glycol, neopentyl glycol, hydroquinone, cyclohexanediol and the like can be mentioned.

  The intrinsic viscosity of the PET resin and film of the present invention is preferably 0.5 to 0.8.

  Moreover, you may mix and use what has a different intrinsic viscosity.

  The method for synthesizing the PET of the present invention is not particularly limited, and can be produced according to a conventionally known method for producing PET.

  For example, a direct esterification method in which a dicarboxylic acid component is directly esterified with a diol component. First, a dialkyl ester is used as a dicarboxylic acid component, this is transesterified with the diol component, and this is heated under reduced pressure. A transesterification method of polymerizing by removing excess diol component can be used.

  At this time, if necessary, a transesterification catalyst or a polymerization reaction catalyst can be used, or a heat-resistant stabilizer can be added. Examples of the heat stabilizer include phosphoric acid, phosphorous acid, and ester compounds thereof. In addition, anti-coloring agents, crystal nucleating agents, slipping agents, stabilizers, anti-blocking agents, UV absorbers, viscosity modifiers, clearing agents, antistatic agents, pH adjusters, dyes, pigments, etc. May be added.

(Fine particles)
Moreover, it is preferable to add 1 ppm-1000 ppm of microparticles | fine-particles of 0.01 micrometer-10 micrometers in said base material for handling property improvement.

  Here, the fine particles may be either organic or inorganic. For example, as the inorganic substance, silica described in Swiss Patent No. 330158, etc., glass powder described in French Patent No. 1,296,995, etc., alkali described in British Patent No. 1,173,181, etc. An earth metal or carbonate such as cadmium or zinc can be used.

  Examples of organic substances include starch described in US Pat. No. 2,322,037 and the like, starch derivatives described in Belgian Patent 625,451 and British Patent 981,198, and the like. No. 44-3643, etc., polyvinyl alcohol described in Swiss Patent No. 330,158 etc., polymethacrylate, US Pat. No. 3,079,257, etc., polyacrylonitrile, US Patent Organic fine particles such as polycarbonates described in US Pat. No. 3,022,169 can be used. The shape of the fine particles may be either regular or irregular.

Substrate according to the present invention, from the viewpoint of imparting the handling aptitude to printing plate material of the present invention, it is preferable that the elastic modulus is ^{300kg / mm 2 ~800kg / mm 2} , more preferably 400 kg / mm ² it is a ~600kg / mm ^2.

  Here, the elastic modulus is obtained by using a tensile tester to obtain the slope of the stress with respect to the strain amount in a region where the strain indicated by the standard line of the sample conforming to JIS C2318 and the corresponding stress have a linear relationship. It is a thing. This is a value called Young's modulus, and in the present invention, the Young's modulus is defined as an elastic modulus.

  Furthermore, in order for the lithographic printing plate material of the present invention to exhibit the effects described in the present invention, the base material according to the present invention is an average film from the viewpoint of improving handling suitability when the printing plate material is installed in a printing machine. It is preferable that the thickness is in the range of 100 μm to 500 μm and the thickness distribution is 5% or less. Especially preferably, it is the range of 120 micrometers-300 micrometers, and thickness distribution is 2% or less. The thickness distribution of the support according to the present invention is a value obtained by dividing the difference between the maximum value and the minimum value of the thickness by the average thickness and expressed as a percentage. Here, the method for measuring the thickness distribution of the support is as follows. The support cut out into a square having a side of 60 cm is drawn in a grid pattern at intervals of 10 cm vertically and horizontally, the thickness of these 36 points is measured, and the average value and maximum value are measured. Find the value and minimum value.

As the substrate according to the present invention, a plastic film support is preferably used, but a material such as a plastic film and a metal plate (for example, iron, stainless steel, aluminum) or paper coated with polyethylene (also referred to as a composite substrate). It is also possible to use a composite support obtained by laminating as appropriate. These composite substrates may be bonded together before forming the coating layer, may be bonded after forming the coating layer, or may be bonded immediately before being attached to the printing press. It is preferable to place an undercoat layer between the material and the hydrophilic layer.

  As the structure of the undercoat layer, a two-layer structure is preferable, and a material that considers adhesiveness is used for the base material side (undercoat lower layer), and the undercoat layer and hydrophilic layer are used for the hydrophilic layer side. It is preferable to use a material that takes into account the adhesiveness to.

  Examples of the material used in the undercoat layer include vinyl polymers, polyesters, styrene-diolefins, and the like. In particular, vinyl polymers and polyesters are preferable, and combinations or modifications thereof are preferable.

  On the other hand, the material that can be used in the undercoat upper layer preferably contains a water-soluble polymer in order to improve the adhesion to the hydrophilic layer, and in particular, an aqueous polymer mainly composed of gelatin and polyvinyl alcohol units, acrylic. Resins and polyester resins are preferred. In view of the adhesiveness to the undercoat layer and the adhesiveness to the hydrophilic layer, it is preferable to mix the material used in the undercoat layer and the water-soluble polymer.

  In the present invention, an embodiment having an undercoat layer containing PET as a base material and containing polyvinyl alcohol, an acrylic resin or a polyester resin, or an aluminum base material and containing carboxymethyl cellulose, polyvinyl alcohol, an acrylic resin or a polyester resin. An embodiment having an undercoat layer is a preferred embodiment.

  In the present invention, by containing the material in the undercoat upper layer, the adhesion between the base material and the hydrophilic layer can be improved, and the foreign matter resistance and on-press developability can be further improved.

The following inorganic particles can be used for the undercoat layer. Examples thereof include inorganic substances such as silica, alumina, barium sulfate, calcium carbonate, titania, tin oxide, indium oxide, and talc. The shape of these fine particles is not particularly limited, and can be used in a needle shape, a spherical shape, a plate shape, or a crushed shape. A preferable size is 0.1 to 15 μm, more preferably 0.2 to 10 μm, and still more preferably 0.3 to 7 μm. The amount of particles added is 0.1 to 50 mg, more preferably 0.2 to 30 mg, and still more preferably 0.3 to ²⁰ mg per 1 m ^{2 on} one side.

  The undercoat layer is preferably from 0.05 to 0.50 μm, more preferably from 0.10 to 0.30 μm, from the viewpoint of transparency and coating unevenness (interference unevenness).

  In the present invention, the undercoat layer is formed on the polyester film on-line or off-line after film formation of the support, in which the coating solution is applied to one or both sides of the polyester film before the completion of crystal orientation, particularly during film formation of the support. It is preferable to apply the coating solution on one or both sides.

  As a coating method for the undercoat layer, any known coating method can be applied. For example, kiss coat method, reverse coat method, die coat method, reverse kiss coat method, offset gravure coat method, Mayer bar coat method, roll brush method, spray coat method, air knife coat method, impregnation method, curtain coat method, etc. alone or in combination To apply.

  It is preferable to provide an antistatic layer on the undercoat layer. The antistatic layer is composed of an antistatic agent and a binder.

A metal oxide is preferably used as the antistatic agent. As an example of the metal oxide, ZnO, TiO ₂ , SnO ₂ , Al ₂ O ₃ , In ₂ O ₃ , SiO ₂ , MgO, BaO, MoO ₂ , V ₂ O ₅ , or a composite oxide thereof is preferable. In particular, SnO ₂ (tin oxide) is preferable from the viewpoints of miscibility with the binder, conductivity, transparency, and the like. As an example including a different element, Sb, Nb, a halogen element or the like can be added to SnO ₂ . The amount of these different elements added is preferably in the range of 0.01 to 25 mol%, particularly preferably in the range of 0.1 to 15 mol%.

(exposure)
In the present invention, it is preferable to form an image on a lithographic printing plate material using a laser beam. Among these, 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 according to the present invention, any apparatus can be used as long as it can form an image on the surface of a printing plate material in accordance with an image signal from a computer using the semiconductor laser. Good.

  In general, (1) a printing plate material held by a flat plate holding mechanism is exposed two-dimensionally using one or a plurality of laser beams to expose the entire surface of the printing plate material. ) The printing plate material held along the cylindrical surface inside the fixed cylindrical holding mechanism is used in the circumferential direction of the cylinder (main scanning direction) using one or more laser beams from inside the cylinder. A method in which the entire surface of the printing plate material is exposed by moving in a direction perpendicular to the circumferential direction (sub-scanning direction) while scanning, and (3) printing held on the surface of a cylindrical drum that rotates about an axis as a rotating body The plate material is printed by moving in the direction perpendicular to the circumferential direction (sub-scanning direction) while scanning in the circumferential direction (main scanning direction) by rotating the drum using one or multiple laser beams from the outside of the cylinder. A method that exposes the entire plate material That.

  In the present invention, the scanning exposure method (3) is particularly preferable, and the exposure method (3) is used particularly in an apparatus that performs exposure on a printing apparatus.

(printing)
A general lithographic printing method using a dampening solution and printing ink can be applied to the printing method of the present invention.

  As a printing method of the present invention, it is particularly preferable to use a fountain solution that does not contain isopronol as the fountain solution (the content is not more than 0.5% by mass with respect to water). is there.

  The printing plate material on which an image is formed as described above can be printed without going through a development process.

  That is, in a preferred embodiment, the printing plate material of the present invention is subjected to image exposure with a laser beam and then developed with dampening water or dampening water and printing ink on a lithographic printing machine.

  The printing plate material after image formation is directly attached to the plate cylinder of the printing press, or the image forming is performed after the printing plate material is attached to the plate cylinder of the printing press, and the water supply roller and / or ink supply is performed while rotating the plate cylinder. The non-image portion of the image forming layer can be removed by bringing the roller into contact with the printing plate material.

  The removal of the non-image area, a so-called on-press development method will be described below.

The removal of the non-image part (unexposed part) 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. Alternatively, it can be performed by various other sequences. 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, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto. In the examples, “parts” represents “parts by mass” unless otherwise specified.

(Preparation of substrate 1)
(PET resin)
0.05 parts by mass of magnesium acetate hydrate was added as a transesterification catalyst to 100 parts by mass of dimethyl terephthalate and 65 parts by mass of ethylene glycol, and transesterification was performed according to a conventional method. To the obtained product, 0.05 part by mass of antimony trioxide and 0.03 part by mass of trimethyl phosphate were added.

  Next, the temperature was gradually raised and the pressure was reduced, and polymerization was carried out at 280 ° C. and 6.65 × 10 Pa to obtain a polyethylene terephthalate (PET) resin having an intrinsic viscosity of 0.70.

  Using the PET resin obtained as described above, a biaxially stretched PET film was prepared as follows.

(Biaxially stretched PET film)
Pelletized PET resin was vacuum-dried at 150 ° C for 8 hours, melted and extruded from a T-die at 285 ° C in a layered form, closely contacted with electrostatic application on a 30 ° C cooling drum, cooled and solidified, and unstretched A film was obtained.

  This unstretched sheet was stretched 3.3 times in the longitudinal direction at 80 ° C. using a roll type longitudinal stretching machine.

  Subsequently to the obtained uniaxially stretched film, the film was stretched by 50% of the total transverse stretching ratio in the first stretching zone 90 ° C. using a tenter-type transverse stretching machine, and further in the second stretching zone 100 ° C., the total transverse stretching ratio 3.3. Stretched to double.

  Subsequently, pre-heat treatment was performed at 70 ° C. for 2 seconds, and heat setting was further performed at the first fixing zone 150 ° C. for 5 seconds, and heat setting was performed at the second fixing zone 220 ° C. for 15 seconds. Next, it was relaxed 5% in the transverse (width) direction at 160 ° C., and after exiting the tenter, it was cooled to room temperature over 60 seconds, the film was released from the clip, slitted, wound up, and wound at a thickness of 175 μm. An axially stretched PET film was obtained. The biaxially stretched PET film had a Tg of 79 ° C. In addition, the thickness distribution of the obtained base material was 2%.

On the image forming functional layer of the biaxially stretched PET film, the surface is subjected to a corona discharge treatment of 8 W / m ² · min, and the undercoat coating liquid a-1 is applied to a dry film thickness of 0.8 μm, and 123 ° C. And undercoat layer A-1 was provided on the hydrophilic side.

Thereafter, the upper surface of the undercoat layer A-1 is subjected to a corona discharge treatment of 8 W / m ² · min, and the undercoat coating liquid a-2 is dried to a thickness of 0. The substrate 1 was coated to 1 μm, dried at 123 ° C. to provide an undercoat layer A-2, and further heat-treated at 140 ° C. for 2 minutes to obtain a substrate 1 on which a single-side undercoat layer had been formed.

(Undercoating liquid a-1)
Styrene / glycidyl methacrylate / butyl acrylate = 60/39/1 (molar ratio) terpolymer copolymer latex (Tg = 75 ° C.) solid content concentration 30% by mass 250 g
Styrene / glycidyl methacrylate / butyl acrylate = 20/40/40 (molar ratio) terpolymer copolymer latex (Tg = 20 ° C.) solid content concentration 30% by mass 25 g
Anionic surfactant S-1 (2% by mass) 30 g
Finished to 1 kg with water.

(Undercoating liquid a-2)
Modified aqueous polyester L-4 solution (23% by mass) 31 g
58 g of 5% aqueous solution of Kuraray Exebar (copolymer of polyvinyl alcohol and ethylene) RS-2117
Anionic surfactant S-1 (2% by mass) 6 g
Hardener H-1 (0.5% by mass) 100 g
Spherical silica matting agent (Nippon Shokubai Co., Ltd. Sea Hoster KE-P50) 2% by mass dispersion
10g
Distilled water was added to make 1000 ml.

(Preparation of aqueous polyester (L-4) solution)
35.4 parts by weight of dimethyl terephthalate, 33.63 parts by weight of dimethyl isophthalate, 17.92 parts by weight of dimethyl sodium 5-sulfoisophthalate, 62 parts by weight of ethylene glycol, 0.065 parts by weight of calcium acetate monohydrate, acetic acid After transesterification of 0.022 parts by mass of manganese tetrahydrate under a nitrogen stream while distilling off methanol at 170 to 220 ° C., 0.04 parts by mass of trimethyl phosphate and trioxide as a polycondensation catalyst 0.04 parts by mass of antimony and 6.8 parts by mass of 1,4-cyclohexanedicarboxylic acid were added, and at a reaction temperature of 220 to 235 ° C., a theoretical amount of water was distilled off for esterification.

  Thereafter, the inside of the reaction system was further depressurized and heated for about 1 hour, and finally subjected to polycondensation at 280 ° C. and 133 Pa or less for about 1 hour to prepare an aqueous polyester.

  The obtained aqueous polyester had an intrinsic viscosity of 0.33 (100 ml / g).

  Moreover, the weight average molecular weight was 80,000-100,000.

  Next, 850 ml of pure water was placed in a 2 L three-necked flask equipped with a stirring blade, a reflux condenser, and a thermometer, and 150 g of aqueous polyester was gradually added while rotating the stirring blade.

  After stirring for 30 minutes at room temperature, the mixture was heated to an internal temperature of 98 ° C. over 1.5 hours and dissolved at this temperature for 3 hours. After completion of the heating, the mixture was cooled to room temperature over 1 hour and allowed to stand overnight to prepare a 15% by mass aqueous polyester solution A1.

<< Preparation of modified aqueous polyester solution >>
1900 ml of the 15% by weight aqueous polyester A1 solution is placed in a 3 L four-necked flask equipped with a stirring blade, a reflux condenser, a thermometer, and a dropping funnel, and the internal temperature is heated to 80 ° C. while rotating the stirring blade. To do.

  Into this, 6.52 ml of a 24% aqueous solution of ammonium peroxide was added, and a monomer mixture (28.5 g of glycidyl methacrylate, 21.4 g of ethyl acrylate, 21.4 g of methyl methacrylate) was dropped over 30 minutes, The reaction is continued for another 3 hours.

  Then, it cooled and filtered to 30 degrees C or less, and prepared the modified aqueous polyester B1 solution (vinyl component modification ratio 20 mass%) whose solid content concentration is 18 mass%. Moreover, what made the vinyl-type component modification | denaturation ratio 5 mass% was set as modified | denatured aqueous polyester L-4.

(Application of lower and upper hydrophilic layers)
The lower hydrophilic layer coating solution having the composition shown in Table 1 below was applied to the undercoating surface of the substrate 1 using a wire bar so that the dry mass was 3.0 g / m ^2, and the length was 15 m and 100 ° C. The set drying zone was passed at a conveying speed of 15 m / min.

Subsequently, the upper layer hydrophilic layer coating solution of the composition shown in Table 2 below was applied using a wire bar so that the dry mass was 1.80 g / m ² , and transported through a drying zone set at 100 ° C. with a length of 30 m. It was passed at a speed of 15 m / min. The sample after application was aged at 60 ° C. for 2 days.

The composition of Table 1 was sufficiently stirred and mixed using a homogenizer, and then filtered to prepare a lower hydrophilic layer coating solution.

The composition shown in Table 2 was sufficiently stirred and mixed using a homogenizer and then filtered to prepare an upper hydrophilic layer coating solution.

(Preparation of image forming layer coating solution)
The image forming layer coating solution having the composition shown in Table 3 below was applied onto the upper hydrophilic layer prepared above using a wire bar so as to have a dry mass of 0.55 g / m ² , and a 70 m length of 70 m. A heat-sensitive image forming layer was formed by passing through a drying zone set at ° C. at a conveying speed of 15 m / min. The coated sample was aged at 50 ° C. for 2 days to obtain a lithographic printing plate material.

  The lithographic printing plate material was cut to a width of 660 mm, and the one using the substrate 1 (PET substrate) was wound 30 m on a paper core having an outer diameter of 76 mm to obtain a rolled lithographic printing plate material. On the other hand, what used the base material 2 (aluminum base material) was also cut to 660 mm width, and the sheet-like planographic printing plate material was obtained.

  As shown in Table 3, spherical particles were added to the hydrophilic layer or the image forming layer, and a roll-like or sheet-like lithographic printing plate material was produced in the same manner as the lithographic printing plate material.

<Evaluation>
Exposure Method The printing plate sample was cut to fit the exposure size, and then wound around the exposure drum and fixed. A laser beam having a wavelength of 830 nm and a spot diameter of about 18 μm is used for exposure, and the exposure energy is 240 mJ / cm ² , and 2,400 dpi (dpi represents the number of dots per 2.54 cm) and an image is formed with 175 lines. Thus, an image-formed printing plate sample was prepared.

Printing method Printing device: DAIYA1-F manufactured by Mitsubishi Heavy Industries, Ltd., fountain solution Astro Mark 3 (manufactured by Nikken Chemical Research Co., Ltd.), 2% by mass, ink is Toyo High Unity M Red (Toyo Ink Co., Ltd.) The product was prepared and evaluated for printing. Other than the printing durability evaluation, printing was performed using Mr. Court. At the time of front printing, powder (trade name: Nikka Rico M (manufactured by Nikka Co., Ltd.)) was used and sprayed on the powder scale 10 of the printing apparatus.

(On-press developability: evaluation of printing)
Good S / N ratio at the time of printing (the non-image area has no background stain, that is, the non-image area of the image forming layer is removed on the printing machine, and the density of the image area is within an appropriate range. In particular, the number of printed sheets until a printed matter having a development defect due to scratches on the image layer due to the mat material of the backcoat layer was obtained was measured and used as an on-press developability index. The smaller the number of waste paper, the better. There are practical problems with 40 sheets or more.

(Print life)
Printing evaluation was performed using a backing paper printed on the above printing conditions using high-quality paper. The printing end point was determined at the stage where either a 3% dot missing in the image or a solid density decrease was confirmed, and the number of sheets was determined. This number was used as an index of printing durability.

(Scratch resistance (ink adhesion))
Before exposure, the material was rubbed with the nail of the index finger, and the actual damage degree on the 20th printed sheet was evaluated according to the following rank, and it was taken as one of the indexes of scratch resistance of the non-image area.

Adhesion of ball-point pen ink on non-image area after development:
○: Ink is not attached ○ △: Slightly ink is attached △: Slightly ink is attached Δ ×: Ink is attached at the same concentration as the 50% mesh portion ×: Solid Ink adheres at the same density as the part (stain)
As a soiling property during long-term storage, the printing plate material is stored for 3 days in an atmosphere of 40 ° C. and 80% RH. After exposure, the color difference between the non-image area of the printed material after printing 10,000 sheets and the paper white, Measurement was made using a color meter SPM-100 manufactured by GretagMacbeth, and the background stain was evaluated by a color difference as an index. If the color difference (ΔE) is 0.5 or more, there is a practical problem.

A: Silica particles 1 (irregular) Mizusawa Chemical JC-70, average particle size: 6 μm
B: Silica particle 2 (spherical porous) Dokai Chemical Sunsphere H-51, average particle size: 6 μm
C: Cellulose 1 (spherical porous) Rengo Recife Average particle size: 8 μm,
D: Cellulose 2 (spherical porous) Rengo Recife Average particle size: 3 μm
E: Cellulose 3 (amorphous) Asahi Kasei Avicel PH-M06 Average particle size: 6 μm
From Table 4, it can be seen that the planographic printing plate material and printing method of the present invention are excellent in on-press developability, printing durability, printing suitability, and scratch resistance.

Claims (5)

In a lithographic printing plate material having a hydrophilic layer containing a photothermal conversion agent and a thermal image-forming layer in this order from the substrate side on the substrate, spherical cellulose particles having an average particle diameter of 3 to 20 μm are formed on the hydrophilic layer. A lithographic printing plate material comprising: In a lithographic printing plate material having a hydrophilic layer containing a photothermal conversion agent and a thermal image forming layer in this order from the substrate side on the substrate, spherical cellulose having an average particle size of 1 to 10 μm in the thermal image forming layer A lithographic printing plate material comprising particles. The lithographic printing plate material according to claim 1, wherein the cellulose particles are porous. The lithographic printing plate material according to any one of claims 1 to 3, wherein the heat-sensitive image forming layer is an on-press developable layer. The lithographic printing plate material according to any one of claims 1 to 4, wherein the lithographic printing plate material is image-exposed with a laser beam, and then developed with dampening water or dampening water and printing ink on a lithographic printing machine. Printing method.