JP2005161863A - Substrate for printing plate and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a substrate for a printing plate for which a hydrophilic surface treatment can be performed by low-cost coating and which ensures performances as a printing plate comparable to or higher than those of an aluminum grained substrate and has a sufficient print wear, and its production method. <P>SOLUTION: In the method for producing a substrate for a printing plate by which a coating liquid containing porous inorganic particles is prepared, coated on the substrate and dried to form a hydrophilic layer, preparation of the coating liquid includes a process for crushing the inorganic particles by mechanical dispersion, and a process for preparing the coating liquid by adding a colloidal silica to the crashed subjects thus obtained. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for producing a support for a printing plate and a support for a printing plate, and more particularly, hydrophilicity that can be formed by coating instead of a conventional support having a hydrophilic surface with a grained surface of an aluminum plate. The present invention relates to a method for producing a printing plate support provided with a conductive layer on a substrate and the support.

  Conventionally, the aluminum support surface of PS plates for lithographic printing plates has been roughened to provide water retention and printing durability, and further an oxide film layer by anodization to provide hydrophilicity and wear resistance. A forming process has been performed.

  The rough surface processing methods are generally chemical (alkali / acid dissolution, etc.), mechanical (brush polishing using an abrasive, sand blasting, liquid honing, rolling with a roughness transfer roll, etc.), electrochemical The roughening of the surface (AC or DC electrolytic treatment in an acidic solution) is known, and the processing of the surface of the support is carried out by appropriately combining some of these methods.

  In particular, electrochemical surface roughening is essential to form pits having a diameter of 0.1 to several μm to improve water retention. However, in order to stably form a uniform rough surface, electrolyte temperature, etc. Is strictly controlled, and the usable aluminum raw fabric has a narrow composition range and requires a good texture uniformity. Moreover, 20-40% highly concentrated sulfuric acid aqueous solution is generally used for anodic oxidation, which has safety problems and environmental problems such as waste liquid treatment.

  On the other hand, as a surface processing method for a printing plate support which does not necessarily require electrochemical surface roughening or anodization, mechanical roughening as disclosed in JP-T-9-504241 (WO95 / 18019) is used. After processing Ra to 0.3 to 1.5 μm by surface treatment, oxide particles are formed as a hydrophilic layer on the surface by thermal spraying (plasma spraying) treatment, as in WO96 / 0620 A method for producing a support for a printing plate has been proposed in which a specific substance is formed as a layer on the surface of the support under a low pressure of 1.9984 × 104 Pa (150 torr) or less by a plasma method. However, roughening by such a plasma spraying method cannot form pits with a diameter of 0.1 to several μm, which makes water retention good, and the printing performance is insufficient. The processing stability in the width direction and the longitudinal direction is lacking, and the cost is not satisfactory.

  WO97 / 1987 proposes a method for producing a printing plate support, which is characterized in that a hydrophilic layer is formed by applying a silicate aqueous solution in which inorganic particles on a substrate are dispersed. Although the method can achieve cost reduction, it cannot provide multiple structures on the surface, has insufficient water volume latitude during printing, and is flexible because the binder is simply water glass. It lacks the properties, has the defects of being easily cracked and easily peeled off, and the printing durability is not satisfactory.

  In JP-A-9-99662, an image-receiving layer provided on a support has a three-dimensional network structure having a porosity of 30 to 80%, and the structure has an average primary particle size of 100 nm or less. An offset printing plate substrate characterized by being formed from inorganic fine particles and a water-soluble resin has been proposed. Only the water latitude and the printing durability are largely inferior.

  Therefore, the object of the present invention is to perform hydrophilic surface processing of a printing plate support by inexpensive coating, and the performance as a printing plate (water latitude, resistance to non-image area contamination, blanket contamination) It is an object of the present invention to provide a printing plate support and a method for producing the same, which have a resistance equal to or greater than that of a grained aluminum plate and sufficient printing durability.

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

  (Claim 1) In a method for producing a support for a printing plate in which a coating liquid containing porous inorganic particles is prepared, coated on a substrate and dried to form a hydrophilic layer, the preparation of the coating liquid comprises: A printing plate comprising a step of crushing the porous inorganic particles by mechanical dispersion, and then a step of preparing a coating solution by adding colloidal silica to the pulverized product obtained by the crushing step For producing a support for an automobile.

  (Claim 2) The method according to claim 1, wherein the step of crushing by mechanical dispersion is wet dispersion.

  (Claim 3) The production method according to claim 2, wherein the coating liquid is prepared without drying the porous inorganic particles crushed by wet dispersion.

  (Claim 4) The particle diameter of the porous inorganic particles after dispersion is substantially 1 μm or less, or the porous inorganic particles of 1 μm or more are substantially removed. The manufacturing method of any one of Claims.

  (Claim 5) The production method according to claim 1, wherein the porous inorganic particles include porous silica particles or porous aluminosilicate particles.

  (Claim 6) The production method according to claim 5, wherein the pore volume of the porous silica particles or the porous aluminosilicate particles is 0.5 ml / g or more.

  (7) The production method according to the above (1), wherein the porous inorganic particles contain zeolite particles.

  (8) The method according to (7), wherein the zeolite particles have an Al / Si ratio of 0.4 to 1.0.

  (Claim 9) The method according to claim 1, wherein the hydrophilic layer contains an organic component, and the organic component contained is 0 to 30% by mass of the entire hydrophilic layer.

  (Claim 10) The method according to claim 1, wherein the hydrophilic layer further contains inorganic particles having a new Mohs hardness of 5 or more.

  (11) The method according to (10), wherein the particle size of the inorganic particles is equal to or greater than the average film thickness of the hydrophilic layer.

  (Claim 12) In a method for producing a support for a printing plate in which a coating liquid containing layered mineral particles is prepared, coated on a substrate and dried to form a hydrophilic layer, the coating liquid is prepared by A step of swelling and peeling the layered mineral particles with a solvent, or a step of peeling and crushing by mechanical dispersion, and then a step of preparing a coating solution by adding colloidal silica to the pulverized product obtained by the step of peeling and crushing A method for producing a support for a printing plate, comprising:

  (Claim 13) The method according to claim 12, wherein the step of peeling and crushing by mechanical dispersion is wet dispersion.

  (Claim 14) The method according to claim 13, wherein the coating liquid is prepared without drying the layered mineral particles peeled and crushed in the step of peeling and crushing by mechanical dispersion.

  (Claim 15) In the step of swelling and peeling the layered mineral particles with a solvent, the layered mineral particles are swellable layered clay mineral particles, and the swellable layered clay mineral particles are swollen with a solvent and have an average thickness of 100 nm or less. The manufacturing method according to claim 12, wherein the thin film is divided into thin layers.

  (16) The coating liquid is prepared without drying the layered mineral particles divided into thin layers in the step of swelling with a solvent and dividing into thin layers having an average thickness of 100 nm or less. Manufacturing method.

  (17) The method according to (12) or (15), wherein the layered mineral particles have a particle size of 20 μm or less and an aspect ratio of 20 or more.

  (18) The method according to (12) or (15), wherein the layered mineral particles have an orientation degree of 0.7 or more with respect to the substrate surface.

  (Claim 19) A printing plate support produced by the production method according to any one of claims 1 to 18.

  (20) The printing plate support according to (19), wherein an ink receptive image layer is provided on the hydrophilic layer.

  According to the present invention, the hydrophilic surface processing of the printing plate support can be performed by inexpensive coating, and the performance as a printing plate (water latitude, resistance to non-image area contamination, blanket contamination) There are provided a printing plate support and a method for producing the same, which are equivalent to or higher than printing plates using a grained aluminum support.

  Hereinafter, the present invention will be described in detail.

  In the present invention, a known material used as a substrate for a printing plate can be used as a base material for a printing plate support. 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 hydrophilic layer, it is preferable to perform an easily bonding process or undercoat layer application | coating to the surface in which a hydrophilic layer is provided. 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 anodic oxidation process and the said immersion or application | coating process. Moreover, you may form the organic-inorganic sol-gel film by the method shown by Unexamined-Japanese-Patent No. 8-240914 on the degreased surface or the surface which anodized. Moreover, the aluminum plate roughened by the well-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. Particularly preferred are polyethylene terephthalate and polyethylene naphthalate. These plastic films are preferably subjected to easy adhesion treatment or undercoat layer coating on the coated surface in order to improve the adhesion to the coated layer. Examples of the easy adhesion treatment include corona discharge treatment, flame treatment, and ultraviolet irradiation treatment. Examples of the undercoat layer include a layer containing gelatin or latex.

  In addition, as the composite base material, it is possible to use a material obtained by appropriately bonding the above materials, but they may be bonded before forming the hydrophilic layer, or may be bonded after forming the hydrophilic layer, You may paste together just before attaching to a printing machine.

  The printing plate support of the present invention has at least one hydrophilic layer containing porous inorganic particles and / or thin layered inorganic particles on a substrate.

  Examples of the porous inorganic particles include porous silica particles, aluminosilicate particles, and zeolite.

  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 be controlled in porosity and particle size by adjusting production conditions. As the porous silica particles, those obtained from a wet gel are particularly preferable.

  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. Moreover, what was manufactured as composite particle | grains of 3 or more components by adding the alkoxide of another metal at the time of manufacture can be used for this invention. These composite particles can also control the porosity and particle size by adjusting the production conditions.

  The porosity of the porous inorganic particles is preferably 0.5 ml / g or more, more preferably 0.8 ml / g or more, and 1.0 ml / g in terms of the pore volume before dispersion. More preferably, it is 2.5 ml / g or less. The pore volume is closely related to the water retention of the coating film. The larger the pore volume, the better the water retention and the less smudged during printing, and the greater the water volume latitude, but greater than 2.5 ml / g. Then, since the particles themselves become very brittle, the durability of the coating film decreases. If the pore volume is less than 0.5 ml / g, it is difficult to stain during printing, and the water amount latitude is insufficient.

  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 general formula combining natural and synthetic zeolite is expressed as follows:

(M ^I , M ^II _1/2 ) _m (Al _m Si _n O ₂ ( _{m + n} )) xH ₂ O
Here, M ^I and M ^II are exchangeable cations, and M ^I is Li ⁺ , Na ⁺ , K ⁺ , Tl ⁺ , Me ₄ N ⁺ (TMA), Et ₄ N ⁺ (TEA), Pr _4. N ⁺ (TPA), C ₇ H ₁₅ N ₂ ⁺ , C ₈ H ₁₆ N ^{+ and the} like, and M ^II is Ca ²⁺ , Mg ²⁺ , Ba ²⁺ , Sr ²⁺ , C ₈ H ₁₈ N ₂ ^{2. +} Etc. Further, n ≧ m, and the value of m / n, that is, the Al / Si ratio is 1 or less. The higher the Al / Si ratio, the greater the amount of exchangeable cations and the higher the polarity and therefore the higher the hydrophilicity. A preferable Al / Si ratio is 0.4 to 1.0, and more preferably 0.8 to 1.0.

As the zeolite particles, synthetic zeolite having a stable Al / Si ratio and a relatively sharp particle size distribution is preferable. For example, zeolite A: Na ₁₂ (Al ₁₂ Si ₁₂ O ₄₈ ) · 27H ₂ O; Al / Si ratio 1.0, zeolite X: Na ₈₆ (Al ₈₆ Si ₁₀₆ O ₃₈₄ ) · 264H ₂ O; Al / Si ratio 0.811, zeolite Y: Na ₅₆ (Al ₅₆ Si ₁₃₆ O ₃₈₄ ) · 250H ₂ O; Al / Si ratio 0.412 and the like.

  By containing highly hydrophilic porous inorganic particles having an Al / Si ratio of 0.4 to 1.0, the hydrophilicity of the hydrophilic layer itself is greatly improved, it is difficult to get dirty during printing, and the water latitude is widened. Also, fingerprint marks are greatly improved. When the Al / Si ratio is less than 0.4, the hydrophilicity is insufficient, and the effect of improving the performance becomes small.

  The particle diameter of the porous inorganic particles is preferably 1 μm or less and more preferably 0.5 μm or less in a state where the particle is contained in the hydrophilic layer (including the case where the dispersion crushing step is performed). When coarse particles are present, porous and steep protrusions are formed on the surface of the hydrophilic layer, so that ink tends to remain around the protrusions and the non-image area stains deteriorate. The content of the porous inorganic particles is preferably 20 to 95% by mass, more preferably 30 to 80% by mass, based on the entire hydrophilic layer on the hydrophilic layer side containing the particles.

  As the thin layered inorganic particles, layered mineral particles can be used. Layered mineral particles include kaolinite, halloysite, chrysotile, talc, smectite (montmorillonite, beidellite, hectorite, saponite, etc.), clay minerals such as vermiculite, mica, chlorite, and hydrotalcite, layered polysilicate. (Kanemite, macatite, ialite, magadiaite, 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 preferred 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), mica (charge density ˜1). Negative charge), hydrotalcite (charge density to 2; positive charge), magadiite (charge density to 1; negative charge), and the like. In particular, synthetic fluoromica is preferable because it can be obtained with stable quality such as particle size. Further, among the layered mineral particles, those that are swellable are preferable, and those that are free swell are more preferable. In addition, intercalation compounds (such as pillared crystals) of the layered mineral, those subjected to ion exchange treatment, and those subjected to surface treatment (such as a silane coupling agent) can also be used.

  As for the size of the thin layered inorganic particles, the particle size (maximum length of the particles) is 20 μm or less, and the aspect ratio (including the case of undergoing the swelling process and dispersion peeling process) contained in the hydrophilic layer. The maximum particle length / particle thickness) is preferably 20 or more, more preferably an average particle size of 10 μm or less and an average aspect ratio of 50 or more. When the particle size is in the above range, the coating film is provided with the continuity and flexibility in the planar direction, which are the characteristics of the thin layered inorganic particles, and it is possible to obtain a tough coating film that is hard to crack. When the particle diameter is out of the above range, the dirt on the non-image area and the blanket dirt may deteriorate with an unnecessary increase in surface roughness. On the other hand, when the aspect ratio is less than the above range, the flexibility becomes insufficient, and the crack suppressing effect of the coating film is reduced. The content of the thin layered inorganic particles is preferably 1 to 50% by mass, and more preferably 3 to 30% by mass of the entire hydrophilic layer on the hydrophilic layer side containing the particles.

  The thin layered inorganic particles can exhibit the effect of strengthening the coating film most efficiently by the presence of the particle surface oriented in parallel to the substrate surface in the hydrophilic layer. The degree of orientation of the thin layered inorganic particles can be controlled by using a coating method in which a shearing force is applied in the coating longitudinal direction when the hydrophilic layer is coated, and adjusting the shearing force. For example, using a reverse roll coater or an extrusion coater, the degree of orientation is adjusted by adjusting the solid content concentration, wet film thickness, coating speed, etc. of the hydrophilic layer coating solution. Further, the degree of orientation can be improved by calendering and compressing the coating film after coating and drying. However, the calendering treatment needs to be performed within a range that does not impair the functions required as a printing plate.

  The degree of orientation of the thin layered inorganic particles is determined by SEM observation of the support cross section. The angle θ formed by the line on the substrate surface of the support cross section and the line on the cross section of the thin layered particle observed in the cross section of the hydrophilic layer is measured (if the line is a curve, the angle formed with the approximate straight line by a linear expression) And cos θ is obtained. The same measurement is performed on the line of the cross section of the thin layered particle having a length of 1 μm or more seen in the cross section, the average value of cos θ is obtained, and this is set as the orientation degree. The degree of orientation is preferably 0.7 or more, and more preferably 0.8 or more. If the degree of orientation is less than 0.7, the effect of strengthening the coating film may be insufficient, or the surface roughness and blanket contamination of the non-image area may deteriorate due to unnecessary increase in surface roughness.

  The thin layered inorganic particles are preferably swellable. The swellable thin layered inorganic particles will be described later.

  A preferred embodiment of the hydrophilic layer of the present invention includes an embodiment containing metal oxide fine particles having an average particle diameter of 100 nm or less in addition to the above particles. Examples of the metal oxide fine particles having an average particle size of 100 nm or less 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. Further, the surface of the particles may be subjected to a surface treatment. 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 is particularly preferable because of its high film forming property even under relatively low temperature drying conditions. In the case of colloidal silica, the smaller the particle size, the stronger the binding force. When the particle diameter is larger than 100 nm, the binding force is greatly reduced, and the strength is insufficient when used as a binder.

  When these metal oxide fine particles are used together with porous silica particles, the fine particles themselves are preferably used in a positively charged state, for example, alumina sol or acidic colloidal silica is preferably used. Further, when these metal oxide fine particles are used together with porous aluminosilicate particles and / or zeolite particles, the fine particles themselves are preferably used in a negatively charged state, for example, alkali colloidal silica is used. It is preferable. When used with porous silica particles and porous aluminosilicate particles and / or zeolite particles, for example, it is preferable to use colloidal silica whose surface is treated with Al to provide stability in a wide pH range.

  A preferred embodiment of the hydrophilic layer of the present invention includes an embodiment containing inorganic particles having a new Mohs altitude of 5 or more. Examples of the inorganic particles include non-porous metal oxide particles (silica, alumina, titania, zirconia, iron oxide, chromium oxide, etc.), metal carbide particles (silicon carbide, etc.), boron nitride particles, diamond particles, and the like. . It is preferable that the particles do not have an acute angle. For example, particles having a nearly spherical shape such as fused silica particles and shirasu balloon particles are preferable.

As an indicator of not being porous, the specific surface area is preferably 50 m ² / g or less in terms of BET value, and more preferably 10 m ² / g or less. Moreover, it is preferable that the particle diameter of the said inorganic particle is more than the average film thickness of the hydrophilic layer of this invention, and the average particle diameter of the said inorganic particle is 1-2 times the layer thickness of a hydrophilic layer. Preferably, it is 1.1 to 1.5 times. Moreover, it is preferable that the particle size distribution of the inorganic particles is sharp, and it is preferable that 60% or more of the total particle size is included in the range of 0.8 to 1.2 times the average particle size, and further, twice the average particle size. The above particles are preferably 5% or less. The content of inorganic particles having a new Mohs hardness of 5 or more is preferably 1 to 50% by mass, more preferably 3 to 30% by mass, based on the entire hydrophilic layer of the present invention.

  The hydrophilic layer of the present invention can contain an organic binder or additive in addition to the particles described above. As the organic binder, those having hydrophilicity are preferable. For example, proteins such as casein, soybean protein, synthetic protein, chitins, starches, gelatins, polyvinyl alcohol, silyl modified polyvinyl alcohol, cationic modified polyvinyl alcohol, cellulose derivatives such as methylcellulose, carboxymethylcellulose and hydroxyethylcellulose, polyethylene oxide , Polypropylene oxide, polyethylene glycol, polyvinyl ether, styrene-butadiene copolymer, conjugated diene polymer latex of methyl methacrylate-butadiene copolymer, acrylic polymer latex, vinyl polymer latex, polyacrylamide, polyvinylpyrrolidone, etc. Is mentioned.

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

  Furthermore, you may add a crosslinking agent in the hydrophilic layer of this invention. Examples of the crosslinking agent include melamine resins, isocyanate compounds, isoxazoles, aldehydes, N-methylol compounds, dioxane derivatives, active vinyl compounds, and active halogen compounds.

A silicate aqueous solution can also be used as a binder component to be added to the coating solution for coating the hydrophilic layer of the present invention. Alkali metal silicates such as sodium silicate, potassium silicate and lithium silicate are preferred, and the SiO ₂ / M ₂ O ratio is in a range where the pH of the whole coating solution does not exceed 13 when silicate is added. Such a selection is preferable from the viewpoint of preventing dissolution of the porous or thin layered inorganic particles.

  As a binder to be added to the hydrophilic layer of the present invention, an inorganic polymer or an organic-inorganic hybrid polymer by a so-called sol-gel method can be used. The formation of inorganic polymers or organic-inorganic hybrid polymers by the sol-gel method is described in, for example, “Application of the sol-gel method” (published by Sakuo Sakuo / Agne Jofusha) or cited in this book. Known methods described in the published literature can be used.

  The organic component as described above contained in the hydrophilic layer of the present invention, even if it is a hydrophilic resin, when it is crosslinked to improve durability, water resistance, etc., the hydrophilicity is greatly reduced, This may cause smudging during printing. In addition, the organic component may block the opening of the porous particles, or may penetrate into the pores, thereby impairing the porosity of the hydrophilic layer and reducing water retention. For the above reasons, it is preferable that the amount of the organic component added is small. Specifically, the amount of the organic component with respect to the entire hydrophilic layer is preferably 0 to 30% by mass ratio, more preferably 0 to 10%, and further preferably 0 to 5%.

  The thickness of the hydrophilic layer of the present invention is preferably 0.2 to 10 μm, more preferably 0.5 to 5 μm. Therefore, the average particle size of the porous inorganic particles and the thin layered inorganic particles is preferably 0.2 to 20 μm, and more preferably 0.5 to 10 μm.

  The hydrophilic layer of this invention can contain components other than the above in the range which does not inhibit the effect of this invention.

  The hydrophilic layer of the present invention can be composed of one layer or can be formed of two or more layers.

  The printing plate support of the present invention may have a layer other than the hydrophilic layer of the present invention. Examples of such a layer include a layer having a function of enhancing the adhesion between the substrate and the hydrophilic layer of the present invention, a hydrophilic layer of the present invention on one surface of the substrate, and an anti-curl layer on the other surface. Can be mentioned.

  The method for producing a printing plate support of the present invention comprises a step of crushing porous inorganic particles by mechanical dispersion and a step of exfoliating and crushing layered mineral particles by mechanical dispersion in the preparation of the coating liquid for hydrophilic layer of the present invention. It is characterized by including.

  A step of crushing porous inorganic particles by mechanical dispersion (hereinafter sometimes abbreviated as “dispersion crushing”) and a layered mineral particle are crushing by mechanical dispersion (hereinafter abbreviated as “dispersion separation”). The process can be roughly divided into dry and wet processes. In the dry dispersion crushing, the drying process is not required, so the process is relatively simple. However, the wet method is usually more advantageous for the dispersion crushing up to the submicron order and the layer peeling up to a layer thickness of 100 nm or less.

  Examples of dry dispersion crushing devices include high-speed rotary impact shearing mills (eg, annular type innomizers), airflow type crushers (jet mills), roll type mills, dry media agitation mills (eg, ball mills), and compression shearing type crushers. (For example, ang mill) can be used. As a wet dispersion crushing apparatus, a wet medium stirring mill (for example, a ball mill or an aquamizer), a high-speed rotating shear friction mill (for example, a colloid mill), or the like can be used.

  The particle diameter of the porous inorganic particles after dispersion and crushing is preferably substantially 1 μm or less, and more preferably 0.5 μm or less. If coarse particles having a particle size of 1 μm or more remain, they may be removed by classification or filtration.

  Further, the layered mineral particles after dispersion and peeling have a thin layer shape with an average particle size (maximum particle length) of 20 μm or less and an average aspect ratio (maximum particle length / particle thickness) of 20 or more. More preferably, the average particle size is 10 μm or less, and the average aspect ratio is 50 or more. Moreover, you may perform the swelling process mentioned later before dispersion | distribution crushing of a layered mineral particle. In particular, when wet dispersion is performed, it is preferable to prepare the coating solution without drying both the porous particles and the layered mineral particles. This is because re-aggregation may occur when the particles subjected to dispersion crushing or dispersion peeling are dried. You may perform concentrating or diluting in order to adjust the solid content density | concentration of a coating liquid.

  Furthermore, in the dispersion crushing or dispersion peeling step, a surface treatment can be performed on the particles by adding a surface treatment agent. In the dispersion crushing or dispersion peeling step, other components added to the coating solution may be added and dispersed simultaneously, or other components added to the coating solution after the dispersion crushing or dispersion peeling step. And may be dispersed again. In the dispersion crushing or dispersion peeling process, it is considered that a mechanochemical reaction occurs at the same time, and when dispersed simultaneously with other components added to the coating solution, the effect of improving the strength when it becomes a coating film is obtained There is.

  When preparing a coating solution for a hydrophilic layer containing swellable lamellar viscous mineral particles, a step of swelling the swellable lamellar viscous mineral particles with a solvent and dividing into a thin layer having an average thickness of 100 nm or less is provided. Is preferred. The swellable synthetic fluorinated mica, which is free swell, swells sufficiently even when mixed and stirred with water, and is divided into thin layers having an average thickness of 10 nm or less to form a stable dispersion. Mg-vermiculite exhibits swellability by performing, for example, the following ion exchange treatment. Mg-vermiculite + lithium citrate aq. → Li-vermiculite + magnesium citrate aq. . Furthermore, Li-vermiculite limitedly swollen by osmotic pressure can be divided into thin layers having an average thickness of 10 nm or less by mechanically dispersing and delaminating.

  The hydrophilic layer of the present invention can be provided on a substrate as follows, for example. The coating liquid for the hydrophilic layer is stirred and mixed after adding a dispersion liquid obtained by crushing and / or peeling porous inorganic particles and / or thin inorganic particles by mechanical dispersion, a binder such as colloidal silica, and other components. Or may be prepared by further dispersing, or may be prepared by adding and mixing porous particles and / or thin layered inorganic particles, a colloidal silica or other binder, and other components, followed by dispersion. Good. Further, filtration may be performed as appropriate.

  As means for applying the hydrophilic layer coating solution on the substrate, known means such as spin coating, wire bar coating, dip coating, air knife coating, roll coating, blade coating, curtain coating, extrusion coating, etc. Can be used. Drying can be performed, for example, in a temperature range of 50 to 100 ° C. when a resin base material is used and in a temperature range of 50 to 300 ° C. when a metal base material is used for about 5 seconds to 10 minutes.

  The printing plate support of the present invention can be formed into an ink-receptive image layer on the hydrophilic layer of the present invention by the following known methods to form a printing plate. The use of the body is not limited to this.

  Examples of the means for providing the ink receptive image layer include a method of forming an ink receptive image layer by attaching an ink receptive material in an image-like manner on the hydrophilic layer of the present invention by a known ink jet method. The ink receiving material is preferably water-resistant, and may be a thermosetting material or a photocurable material that is cured by heat or light after hot melt or image formation. The technique described in JP-A-9-99662 can be applied to the thermosetting substance and the photocurable substance. In addition, the thermal transfer layer of the sheet having an ink-receptive thermal transfer layer by a known thermal transfer method is closely attached to the hydrophilic layer surface of the present invention, and is heated imagewise by a thermal head or laser light from the sheet side, A method of forming an ink-receptive image layer by transferring a heat-sensitive transfer layer of a heated portion from a sheet to the surface of the hydrophilic layer, and then removing the sheet. A method of forming an ink-receptive image layer by coating on a photosensitive layer and, after exposure, removing a soluble portion by development, a known heat (infrared) curable or heat (infrared) soluble photosensitive layer is hydrophilic Examples include a method of forming an ink receptive image layer by coating on the layer, removing the soluble part by development after laser exposure, and the like. Examples of the photosensitive layer include the following photosensitive layers.

  O-naphthoquinone diazide sulfonic acid ester of polycondensation resin of polyhydroxyphenol and ketone or aldehyde, layer of photosensitive composition containing alkali-soluble resin; polymer compound having hydroxyphenyl methacrylamide in molecular structure; Layer of photosensitive composition containing o-quinonediazide compound; Layer of photosensitive composition containing co-condensation-polymerized phenol and m-, p-mixed cresol and aldehyde; o-quinonediazide compound; o A layer of a photosensitive composition containing a quinonediazide compound, an s-triazine compound, a dye that changes color tone by interaction with the photodecomposition product of the s-triazine compound, an alkali-soluble resin; an ethylenically unsaturated compound capable of addition polymerization A compound having at least one double bond, having an aromatic hydroxyl group in the side chain Photosensitivity containing a compound and / or a compound having an aliphatic hydroxyl group in the side chain as a constituent unit in the molecule, an acidic vinyl copolymer soluble or swellable in alkaline water, a photopolymerization initiator, and a diazo resin Layer of composition; layer of photosensitive composition containing acid generator, acid decomposition compound, infrared absorber; layer of photosensitive composition containing acid generator, compound insolubilized with acid, infrared absorber, and the like.

Preparation of dispersion of porous inorganic particles and dispersion of layered mineral particles Dispersion [1]: Silojet P-403, a porous silica particle (manufactured by GRACE Davison, pore volume 2.05 ml / g, average particle diameter) 3 μm) was gradually added to pure water while stirring to obtain a dispersion having a solid content of 20% by mass.

  Dispersion [2]: Silton B (Mizusawa Chemical Co., Ltd., Al / Si ratio = 1.0, average particle size 1.5 μm), which is a synthetic A-type zeolite (porous inorganic particles), is stirred in pure water. The resulting mixture was gradually added to obtain a dispersion having a solid content of 20% by mass.

  Dispersion [3]: AMT silica # 100B, a porous aluminosilicate (manufactured by Mizusawa Chemical Co., Ltd., pore volume of 0.5 ml / g or more (70 ml / 100 g as the oil absorption), average particle size of 1.0 μm) is purified water The mixture was gradually added while stirring to obtain a dispersion having a solid content of 20% by mass.

  Dispersion [4]: Non-swelling synthetic mica (layered mineral) Micromica MK-100 (manufactured by Co-op Chemical, average particle size of 1 to 5 μm, aspect ratio of 20 to 30) was gradually stirred while stirring in pure water. To obtain a dispersion having a solid content of 20% by mass.

  Dispersion [5]: Somasifu ME-100 (manufactured by Co-op Chemical, average particle size of 1 to 5 μm, aspect ratio of 20 or more), which is a swellable synthetic mica (swellable layered mineral), is gradually added while stirring in pure water. This was added to obtain a dispersion (colloid solution) having a solid content of 5% by mass. It is considered that the particles are almost completely swollen, and the average thickness of the particles is 100 nm or less and the aspect ratio is 50 or more.

  Dispersion [6]: Dispersion [1] was dispersed at 1000 rpm for 1 hour using a sand grinder and Hibee 20 as hard glass beads as the medium. After dispersion, the glass beads were removed by filtration to obtain a dispersion [6]. When the dispersion [6] was thinly applied on a polyethylene terephthalate film and dried, then SEM observation was performed. As a result, the porous silica particles were crushed and the particle size was substantially 1 μm or less.

  Dispersion [7]: Dispersion [2] was treated under the same conditions as dispersion [6] to obtain a dispersion. When SEM observation was performed in the same manner as in the dispersion [6], the zeolite particles were crushed and the particle size was substantially 1 μm or less.

  Dispersion [8]: Dispersion [3] was treated under the same conditions as dispersion [6] to give dispersion [8]. When SEM observation was performed in the same manner as in the dispersion [6], the aluminosilicate particles were crushed and the particle diameter was substantially 1 μm or less.

  Dispersion [9]: Dispersion [4] was treated under the same conditions as dispersion [6] to obtain dispersion [9]. When SEM observation and SEM observation from the cross-sectional direction were performed in the same manner as in the dispersion [6], delamination progressed, the aspect ratio was about 50, and the average thickness of the particles was 100 nm or less.

Preparation of Coating Solution for Hydrophilic Layer A coating solution for hydrophilic layer (before filtration) is prepared under the composition and dispersion conditions shown in Tables 1 to 12 below, and the coating solution for hydrophilic layer [1-1] is filtered. [1-26] and [2-1] to [2-6] were obtained. The coating liquids described in the above tables were observed by SEM in the same manner as the dispersions [5] to [7], and the shapes of the porous particles and the layered mineral particles were confirmed. The results are shown in the following tables. It was.

Preparation of Printing Plate Supports Printing plate supports of Examples, Reference Examples and Comparative Examples were prepared by combinations of hydrophilic layer coating solutions, base materials and coating thicknesses having the compositions shown in Tables 13 to 15 below. . The hydrophilic layer was applied with a wire bar. In order to obtain a set film thickness, the count of the wire bar was appropriately changed according to the coating solution composition, solid content concentration, and the like. After coating, it was dried at 100 ° C. for 30 seconds. Further, only Reference Examples 35 and 36 were applied by spraying and dried under the same drying conditions. The conditions of each substrate described in the column of the substrate in Tables 13 to 15 are as follows.

PET substrate 1
A two-layer undercoat layer was formed on a polyethylene terephthalate film having a thickness of 0.18 mm by the following method.

1) First undercoat layer After the corona discharge treatment was applied to the coated surface of the polyethylene terephthalate film, the coating solution for the first undercoat layer having the following composition was dried with a wire bar in an atmosphere of 20 ° C. and a relative humidity of 55%. It applied so that the film thickness after that might be set to 0.4 micrometer. Thereafter, drying was performed at 140 ° C. for 2 minutes.

First undercoat layer coating liquid Acrylic latex particles: n-butyl acrylate / t-butyl acrylate / styrene / hydroxyethyl methacrylate = 28/22/25/25
0.36g
Surfactant (A) 0.36g
Hardener (a) 0.98g
Distilled water was added to make 1000 ml, and a coating solution was obtained.

2) Second undercoat layer After the corona discharge treatment was applied to the surface of the above-mentioned film on which the first undercoat layer was formed, a second undercoat layer coating solution having the following composition was aired in an atmosphere of 35 ° C. and a relative humidity of 22%. It applied so that the film thickness after drying might be set to 0.1 micrometer with the knife system. Thereafter, drying was performed at 140 ° C. for 2 minutes.

Coating solution for second undercoat layer 9.6 g of gelatin
Surfactant (A) 0.4g
Hardener (b) 0.1g
Distilled water was added to make 1000 ml, and a coating solution was obtained.

Al substrate 1
A 1050 aluminum substrate having a thickness of 0.24 mm was degreased by dipping at 50 ° C. for 30 seconds using a 2 mass% aqueous sodium hydroxide solution. After thoroughly washing with water, it was immersed in a 2% by weight No. 3 sodium silicate aqueous solution at 70 ° C. for 30 seconds, washed with water, and then sufficiently dried.

Al base 2
An aluminum substrate degreased in the same manner as the Al substrate 1 was anodized at a voltage of 20 V at 25 ° C. using a 20 mass% aqueous sulfuric acid solution to form a 0.5 g / m ² anodized film. After washing with water, sodium silicate treatment was performed in the same manner as the Al base 1.

Al base 3
The aluminum substrate degreased in the same manner as the Al substrate 1 was immersed and neutralized in a 2.0% by mass aqueous nitric acid solution for 10 seconds, and the peak current density was 30 ° C using a 2.0% by mass nitric acid aqueous solution. The electrolytic surface roughening treatment was performed so that the positive electric quantity was 500 C / dm ² with a sine wave of 60 A / dm ² . Subsequently, using a 1 mass% sodium hydroxide aqueous solution, it was immersed for 20 seconds at 30 ° C., washed with water, and then subjected to anodic oxidation treatment and sodium silicate treatment in the same manner as the Al base 2.

Al base 4
An organic-inorganic sol-gel film was formed on the surface of an aluminum plate on which an anodized film was formed in the same manner as the Al base 2 by the same method as described in Example 1 of JP-A-8-240914. .

  The following evaluation was performed on the printing plate support.

Physical property evaluation and printing evaluation physical property evaluation for printing plate supports of Examples, Reference Examples and Comparative Examples Degree of coating film cracks The degree of coating film cracks in the hydrophilic layer was evaluated by SEM observation. The meanings of symbols in Table 13 and Table 15 are as follows.

◎: No cracks are observed ○: Slight cracks are observed △: Cracks are observed but not continuous ×: The cracks are continuously peeled in a mosaic tile shape, and the support for printing plate is 4 mmφ After repeating the operation of wrapping 180 ° with the hydrophilic layer surface outward and returning it to the round bar 10 times, affix the adhesive tape to the hydrophilic layer surface of the wound portion, peel off, and peel off the hydrophilic layer The presence or absence was evaluated by SEM observation. The meanings of symbols in Table 13 and Table 15 are as follows.

◎: No peeling is observed ○: Slight peeling is seen but the substrate surface is hardly exposed △: The substrate surface is peeled off by 5% or more in area ratio ×: 10% in area ratio Abrasion resistance of the coating film with the substrate surface exposed by using the above. Using a wear resistance tester (HEIDON-18), attach a stylus that is a 1 mmφ steel ball to the tip and apply a load of 50 g. The wear scar after sliding the surface of the hydrophilic layer back and forth 10 times at a speed of 20 cm / min was evaluated. The meanings of symbols in Table 13 and Table 15 are as follows.

◎: No particular wear is observed. ○: Slight wear is observed. △: The width of the wear mark is 0.4 mm or more. ×: The base plate surface of the worn portion is exposed or scratches due to wear pieces are generated. Preparation An ink having the following composition was used, and an image was formed by an inkjet method. Then, it dried at 100 degreeC for 2 minutes, and was set as the printing plate. Image formation by the inkjet method was performed at a resolution of 720 dpi with an ink discharge amount such that one dot has a diameter of about 40 μm on the plate surface.

Ink composition Latex particles: Yodosol GD87B aqueous dispersion 170 parts by mass (manufactured by Kanebo NSC, average particle size 90 nm, Tg 60 ° C., solid content 50% by mass)
Carboxymethylcellulose CMC-1220 (manufactured by Daicel Chemical Industries, Ltd.)
5 parts by mass Carbon black aqueous dispersion (containing dispersant) SD9020 33 parts by mass (Dainippon Ink Co., Ltd., primary particle size 100 nm or less, solid content 30% by mass)
Pure water was added to the above to adjust the solid content concentration to 7.0 mass%.

Printing evaluation conditions Printing machine: Heidel GTO, coated paper, dampening water (H liquid SG-51, Tokyo Ink Co., Ltd., concentration 1.5%), ink (Toyo Ink Mfg. Co., Ltd. High Plus M Red) ) Was used for printing.

Resistance to stain on non-image area The degree of stain on the non-image area on paper was visually determined when 1000 sheets were printed.

Opening of shadow part The degree of opening of the shadow part (70% halftone dot part at 120 lines as an image) at the time when 1000 sheets were printed was visually determined.

Fingerprint trace stain The degree of stain at the time of printing 1000 sheets of the portion where the fingerprint trace was previously made on the non-image area before printing was judged visually.

Stain recovery property After printing 1,000 sheets, the dampening water was turned off, only ink was applied to the entire printing plate, dampening water was supplied again, and printing was resumed. The degree of soiling on the non-image area on the paper surface was stained and evaluated for its resilience with the number of printed sheets equivalent to that at the time when 1000 sheets were printed (the more the number of sheets, the more defective).

Measurement of surface roughness Ra of hydrophilic layer Surface roughness Ra was measured using an optical three-dimensional surface roughness meter: RST plus manufactured by WYKO. The measurement conditions were objective lens × 40 and intermediate lens × 1.0, and a 111 × 150 μm field of view was measured at n = 5 to obtain an average value. Since the coating film (hydrophilic layer) is light-transmitting, the surface of the sample was coated with Al to a thickness of about 50 nm by vapor deposition and then measured.

Printing Evaluation Preparation of Printing Plate A thermal transfer layer (1.5 μm) having the following composition was formed on a 50 μm thick polyethylene terephthalate film to prepare a thermal transfer sheet. The heat-sensitive transfer layer of this heat-sensitive transfer sheet and the hydrophilic layer surface of the printing plate support are brought into close contact, wound around a drum of a laser exposure machine so that the heat-sensitive transfer sheet is on the outside, and imagewise exposed with an 830 nm infrared laser. Then, the image layer was thermally transferred to obtain a printing plate.

Composition of thermal transfer layer Latex particles: 100 parts by weight of Yodosol GD87B aqueous dispersion (manufactured by Kanebo NSC, average particle size 90 nm, Tg 60 ° C., solid content 50% by mass)
125 parts by mass of microcrystalline wax emulsion A206 (manufactured by Gifu Setac Co., Ltd., average particle size 0.5 μm, softening point 65 ° C., melting point 108 ° C., melt viscosity at 140 ° C., 8 cps, solid content 40% by mass)
Carbon black aqueous dispersion (containing dispersant) SD9020 50 parts by mass (Dainippon Ink Co., Ltd., primary particle size 100 nm or less, solid content 30% by mass)
Pure water was added to make the solid content concentration 20.0% by mass.

Conditions for printing evaluation Printing machine: DAIYA1F-1 manufactured by Mitsubishi Heavy Industries, Ltd., coated paper, dampening water (Tokyo ink Co., Ltd. H liquid SG-51 concentration 1.5%), ink (Toyo Ink Manufacturing ( Printing was carried out using Hi-Plus M Red, Inc.

Dirt resistance when reducing the amount of water We compared the resistance to dirt when the dampening water supply amount (set value) was lowered (stains on the halftone dots and non-image areas).

Water amount latitude The amount of change in the set value at which good print quality was obtained when the dampening water supply amount (set value) was changed was determined and compared.

Small dot reproducibility When 2000 sheets were printed, it was compared whether dots formed with a diameter of 25 μm on the printing plate could be confirmed on the paper surface.

Blanket stain When 2000 sheets were printed, the stain accumulated on the blanket was peeled off with an adhesive tape, and the tape was pasted on a white paper to compare the degree of stain.

Printing durability Printing was performed until ink imperfection appeared in the image area of the printed matter, and the number of printed sheets at that time was determined to evaluate printing durability.

  The orientation degree of the layered mineral particles in the hydrophilic layer of the printing plate support of Reference Examples 16, 17, 35 and 36 was measured by SEM observation of the cross section of the coating layer. The details of the method are as described above, and the higher the degree of orientation, the higher the coating strength. The results and physical property evaluation results are shown in Table 15 above.

Claims (20)

In a method for producing a support for a printing plate in which a coating liquid containing porous inorganic particles is prepared, and coated on a substrate and dried to form a hydrophilic layer, the preparation of the coating liquid includes the steps of preparing the porous inorganic particles. A support for a printing plate, comprising: a step of crushing by mechanical dispersion, and then a step of preparing a coating liquid by adding colloidal silica to the pulverized product obtained by the crushing step Method. The method according to claim 1, wherein the step of crushing by mechanical dispersion is wet dispersion. The production method according to claim 2, wherein the coating liquid is prepared without drying the porous inorganic particles crushed by the wet dispersion. The particle diameter of the porous inorganic particles after dispersion is substantially 1 μm or less, or the porous inorganic particles of 1 μm or more are substantially removed. The manufacturing method as described. 2. The production method according to claim 1, wherein the porous inorganic particles include porous silica particles or porous aluminosilicate particles. 6. The production method according to claim 5, wherein the pore volume of the porous silica particles or the porous aluminosilicate particles is 0.5 ml / g or more. The production method according to claim 1, wherein the porous inorganic particles include zeolite particles. The production method according to claim 7, wherein the zeolite particles have an Al / Si ratio of 0.4 to 1.0. The manufacturing method according to claim 1, wherein an organic component is contained in the hydrophilic layer, and the contained organic component is 0 to 30% by mass of the entire hydrophilic layer. The manufacturing method according to claim 1, wherein the hydrophilic layer further contains inorganic particles having a new Mohs hardness of 5 or more. The method according to claim 10, wherein the particle size of the inorganic particles is equal to or greater than the average film thickness of the hydrophilic layer. In a method for producing a support for a printing plate in which a coating liquid containing layered mineral particles is prepared, coated on a substrate and dried to form a hydrophilic layer, the coating liquid is prepared by using the layered mineral particles as a solvent. Characterized in that it has a step of swelling and peeling in step, or a step of peeling and crushing by mechanical dispersion, and then adding a colloidal silica to the pulverized product obtained by the step of peeling and crushing to prepare a coating solution. A method for producing a printing plate support. The method according to claim 12, wherein the step of peeling and crushing by mechanical dispersion is wet dispersion. The manufacturing method according to claim 13, wherein the coating liquid is prepared without drying the layered mineral particles peeled and crushed in the step of peeling and crushing by mechanical dispersion. The step of swelling and peeling the layered mineral particles with a solvent is the layered mineral particles are swellable layered clay mineral particles, and the swellable layered clay mineral particles are swollen with a solvent and divided into a thin layer having an average thickness of 100 nm or less. The manufacturing method according to claim 12, wherein the manufacturing method is a step of causing the above to occur. 16. The production method according to claim 15, wherein the coating liquid is prepared without drying the layered mineral particles divided into thin layers in the step of swelling with a solvent and dividing into thin layers having an average thickness of 100 nm or less. The method according to claim 12 or 15, wherein the layered mineral particles have a particle size of 20 µm or less and an aspect ratio of 20 or more. The method according to claim 12 or 15, wherein the layered mineral particles have an orientation degree of 0.7 or more with respect to the substrate surface. A printing plate support produced by the production method according to any one of claims 1 to 18. 20. The printing plate support according to claim 19, wherein an ink receptive image layer is provided on the hydrophilic layer.