JP2005022419A - Printing-plate support and manufacture method for the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a printing-plate support improved in printability (water-quantity latitude), scumming and blanket-smudging, and a manufacturing method for the same. <P>SOLUTION: In the manufacturing method for the printing-plate support having a hydrophilic layer on a substrate, firstly, a hydrophilic layer is formed on the substrate and then the layer is partially removed so that the hydrophilic layer has a pitted region having a film-thickness smaller than the average film-thickness at an average pitch of 0.2-50 μm. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a printing plate support suitable for a CTP (Computer to Plate) system and a method for producing the same, and more specifically, to improve water retention of a non-image area of a printing plate printed using dampening water, and It relates to improving the sensitivity of printing plates using wax-containing image layers. In the present specification, the printing plate means a planographic printing plate, and in addition to a normal printing plate, a printing plate that has an image recording layer on a substrate and is subjected to imagewise exposure or the like to form a printing plate. Means a material to be made.

  With the digitization of print data, there is a need for materials and methods suitable for CTP systems that are inexpensive, easy to handle, and have the same printability as PS plates. In particular, in recent years, CTP using an ink jet recording method and various types of CTP using infrared laser recording have been proposed.

  As the support of the printing plate used in the CTP by the ink jet method, it is considered that the aluminum grain used in the conventional PS plate is used. Many supports with a hydrophilic layer on the surface have been proposed.

  Also, printing plate materials called so-called dry CTP (including development on a printing press) that do not require special development processing among various types of CTP printing plates using infrared laser recording have attracted attention. Examples of this type include those described in JP-A-8-507727, JP-A-6-186750, JP-A-6-199064, JP-A-7-314934, and the like.

  In JP-A-6-186750, a plate having a first layer and a second layer having different affinity for ink or an ink adhesion preventing liquid is scanned with an infrared laser, and one or more of these layers are ablated. A method and apparatus for removing and forming an image is disclosed.

  In JP-A-6-199064, an upper layer first layer which is an infrared absorption layer and a second layer which is a lower layer thereof are provided on a substrate, or an upper layer first layer and an infrared absorption layer which is a lower layer thereof. There is disclosed a lithographic printing plate material for laser recording, which has a second layer, the first layer and the second layer have different affinity for ink or an ink adhesion preventing liquid, and forms an image by ablation .

  Japanese Patent Application Laid-Open No. 7-314934 has a top layer that is not ablated, a titanium or titanium alloy thin layer metal layer that is ablated, and a substrate, and the top layer and the substrate have different affinity for ink or ink insoluble fluid. A laser recording printing member exhibiting properties and a method of forming an image by ablation are disclosed.

  Japanese Patent Application Laid-Open No. 10-58636 has a laser-sensitive hydrophilic swelling layer (preferably containing a color pigment or a black dye) on a substrate, and the hydrophilic swelling layer is removed by ablation by laser irradiation. A lithographic printing plate precursor for forming a solid image is disclosed.

  However, none of the printing plates obtained by these techniques have satisfactory printing suitability, and the surface shape of the hydrophilic layer is particularly taken into consideration especially in the type of printing plate using a fountain solution. Furthermore, the printing latitude is narrower than that of the PS plate using aluminum grain, and the soiling properties such as blanket soiling and soiling recovery are also inferior.

  In order to improve printing latitude in printing using fountain solution, JP-A-10-58636 proposes to provide a laser-sensitive hydrophilic swelling layer on a substrate. Even if the durability is low and it is possible to improve the printing latitude at the initial stage of printing, it is difficult to maintain the performance, and the ink emulsion penetrates into the swelling layer itself to lower its hydrophilicity. There is a concern that printing stains occur.

  On the other hand, as a material for CTP, a heat-sensitive lithographic printing plate having a hydrophilic layer containing a microencapsulated lipophilic component and a hydrophilic binder polymer on a support is exposed to a parent surface from which the exposed portion surface is released from the capsule. A technique for obtaining a lithographic printing plate by making it oleophilic with an oily component is disclosed (Japanese Patent Laid-Open No. 7-1849). However, the printing original plate has insufficient sensitivity for practical use.

  An object of the present invention is to firstly provide a printing plate support in which printability (water latitude), ground stain and blanket stain are improved, and secondly, an improved sensitivity. It is to provide a printing plate support having an image layer containing a heat-meltable material (such as wax) and a method for producing the same.

  The above object of the present invention has been achieved by the following.

  (Claim 1) In the method for producing a support for a printing plate having a hydrophilic layer on a substrate, the hydrophilic layer is partially removed after the hydrophilic layer is formed on the substrate. A method for producing a support for a printing plate, comprising forming a hydrophilic layer having an area having a pit shape with a film thickness smaller than the average film thickness at an average pitch of 0.2 to 50 μm.

  (Claim 2) After forming the image recording layer and the hydrophilic layer in this order on the substrate, the hydrophilic layer is partially removed, so that the hydrophilic layer has an average of 0.2 to 50 μm. A method for producing a support for a printing plate, comprising a hydrophilic layer having a pit shape with a thickness smaller than an average film thickness at a pitch.

  (Claim 3) The area | region which has the pit shape whose film thickness is thinner than average film thickness by the pitch of 0.2-50 micrometers on average obtained by the manufacturing method of the support body for printing plates of Claim 1 or 2 A support for a printing plate having a hydrophilic layer.

  ADVANTAGE OF THE INVENTION According to this invention, the printing plate support body by which printability (water amount latitude), ground dirt, and blanket dirt are improved, and its manufacturing method are provided. Further, a printing plate support having an image recording layer containing a heat-meltable material having improved sensitivity and a method for producing the same are provided.

  The present invention forms a surface shape suitable for printing by forming a thin region with a pitch of 0.2 to 50 μm on average on a hydrophilic layer that becomes a non-image part at the time of printing. . Particularly preferably, the thin film region has a pit shape, which closely resembles the shape of the PS plate aluminum grain, and the PS plate aluminum is synergistic with the high hydrophilicity of the hydrophilic layer material. It is possible to maintain hydrophilicity that surpasses the grain.

  In addition, as the support for the CTP printing plate by the ink jet method, when the ink is oil-based ink, it has the effect of holding the ink in the hydrophilic pit shape portion to suppress the spread, so that the resolution can be improved. In the case where the ink is a solid melt ink, there is an advantage that the ink bites into the pit shape portion and the printing durability is improved by the anchoring effect.

  Further, in a CTP printing plate of an infrared laser recording type having a layer containing a heat-meltable ink-accepting material on a substrate and having a hydrophilic layer thereon, the hydrophilic layer is averaged. A region having a thin film thickness at a pitch of 0.2 to 50 μm, in particular, a thin film region having a pit shape not only improves printability but also a region where the hydrophilic layer is thin. In this case, the ink receptive material is easily leached, so that the necessary exposure energy for causing ink deposition is reduced and a highly sensitive CTP can be obtained.

  As the support for a printing plate and the base material of the printing plate of the present invention, a known material can be used for the substrate of the printing plate. 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 be used 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 material include polyethylene terephthalate, polyethylene naphthalate, polyimide, polyamide, polycarbonate, polysulfone, polyphenylene oxide, and cellulose esters. In particular, polyethylene terephthalate and polyethylene naphthalate are preferable. These plastic films are preferably subjected to easy adhesion treatment or undercoat layer coating on the coated surface in order to improve adhesion with the coated layer. Examples of the easy adhesion treatment include corona discharge treatment, flame treatment, plasma treatment, and ultraviolet irradiation treatment. Examples of the undercoat layer include a layer containing gelatin or latex.

  In addition, as the composite base material, the above materials are appropriately bonded together, but may be bonded before forming the hydrophilic layer, or may be bonded after forming the hydrophilic layer. You may paste together just before attaching.

The support for a printing plate of the present invention and the hydrophilic layer of the printing plate are formed once, after forming a layer by, for example, applying a hydrophilic layer coating solution on a substrate and drying the layer. By removing them, a region having a film thickness thinner than the average film thickness is formed at an average pitch of 0.2 to 50 μm. In the case of a printing plate, the area preferably has an average pitch of 1 to 50 μm. (Hereinafter, these regions are referred to as “region A”)
In the present invention, it is preferable that the region A has a pit shape, that is, a hole shape.

  The average film thickness is measured by observing the cross section of the sample with a scanning electron microscope (SEM). Specifically, an SEM image having a cross section of 5000 times is taken as a digital image, and five fields of view are photographed for one sample, image processing is performed, and the average film thickness of the hydrophilic layer portion is calculated.

  In the present invention, “with an average pitch of 0.2 to 50 μm” means that the most frequently observed period is within the range of 0.2 to 50 μm among the periodicity of irregularities formed on the surface of the hydrophilic layer. It means that there is. Specifically, it is determined from SEM observation of the cross section of the sample. SEM images of the cross section (selected by looking at the uneven state from 1000 ×, 5000 ×, and 10,000 ×) are continuously captured as a 5-view digital image, and the uneven state on the surface of the hydrophilic layer is digitized and roughened. Let it be a curve. An FFT process is performed on the roughness curve to obtain a power spectral density. The period with the strongest periodicity is defined as the average pitch.

  In printing using fountain solution, the surface shape is very important in addition to hydrophilicity as a material for the hydrophilic layer in order to improve printability.

  First of all, it is possible to further improve the hydrophilicity by increasing the surface area of the hydrophilic material. This is closely related to porosity in the order of several nm to several hundred nm, and can be achieved by adding a porous material or fine particles having a particle diameter of several nm to several hundred nm in the hydrophilic layer. .

  Second, it has a proper surface shape. This is preferably formed by overlapping a wave component of the order of several μm to 50 μm and a fine roughness of the order of 0.2 μm to several μm. The fine roughness of the order of 0.2 μm to several μm preferably has a pit shape. By making the pit shape, the surface can be completely covered with an extremely thin water film, Printing latitude and dirtiness are improved.

  The conventionally proposed hydrophilic layer formed by coating or spraying or the like is formed by blending particles having a corresponding diameter with a fine roughness of the order of 0.2 μm to several μm. However, with a roughness forming means that only adds particles, the roughness shape is convex, and a more advantageous concave or pit-like roughness cannot be formed.

  In the present invention, by partially removing the hydrophilic layer after forming the hydrophilic layer, it is possible to form concave roughness, particularly pit-like roughness.

  Partial removal of the hydrophilic layer can be achieved by, for example, forming a part of the hydrophilic layer with a weak binding force or a part with low water resistance, and rubbing the surface of the hydrophilic layer with an adhesive roll or the like. This can be done by means of peeling off a part of the film, washing it with a high-pressure water stream, or rubbing it in water.

  In addition, when the hydrophilic layer of the present invention is applied to a printing plate for CTP for infrared laser recording having image forming ability on a plate, the hydrophilic layer is partially removed and the plate is set in a printing machine. Then, it can be performed by applying some force by contacting the ink roll or blanket while supplying dampening water while rotating the plate cylinder on the printing press.

  For the formation of a part having a weak binding force or a part having a low water resistance in the hydrophilic layer, for example, as a binder for the hydrophilic layer, colloidal silica having a relatively weak particle size of 50 nm or more, alumina sol Alternatively, it can be carried out by adding an appropriate amount of a water-soluble resin.

  In addition, a portion having a weak binding force can be partially formed by adding a filler having a relatively low binding force to other materials contained in the hydrophilic layer. For example, flat clay minerals, general inorganic particles, porous inorganic particles, organic particles, porous organic particles, and the like. In particular, particles having a nearly spherical shape are preferable because the portion from which the particles are removed forms a pit shape. These fillers are preferably hydrophilic.

  The particles for forming the pit-like roughness on the surface of the hydrophilic layer by being included in the hydrophilic layer and then removed are particles having a relatively low binding force with materials other than the particles forming the hydrophilic layer. is there. The average particle size of the particles is preferably 0.2 to 10 μm, more preferably 0.5 to 6 μm. The amount of the particles added is preferably 20 to 90% by mass, more preferably 30 to 70% by mass, based on the entire hydrophilic layer. Further, the density of the particles when the hydrophilic layer is formed is preferably 50 μm or less, more preferably 30 μm or less, and more preferably 10 μm or less on average from the closest packing to the inter-particle distance. Further preferred.

  In a printing plate of an infrared laser recording system of a type having a layer (image recording layer) containing a heat-meltable ink-accepting material on a substrate and having the hydrophilic layer of the present invention on the layer, The film thickness of the region A formed in the hydrophilic layer is preferably 0.5 μm or less, more preferably 0.3 μm or less at the thinnest portion (for example, at the bottom of the pit shape), 0 More preferably, it is 2 μm or less.

A material for forming a region A, a part for forming a part having a weak binding force or a part having low water resistance in the hydrophilic layer, and the hydrophilic layer contained in the hydrophilic layer and then removed. As particles that form pits on the surface, particles such as the following (a) to (h) and binders such as the following (i) to (k) can be used.
(A) Porous silica or porous aluminosilicate particles Porous silica particles are generally produced by a wet method or a dry method. In the wet method, it can be obtained by drying and pulverizing a gel obtained by neutralizing an aqueous silicate solution, or by pulverizing a precipitate deposited after neutralization. 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 the 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. The ratio of alumina to silica in the particles can be synthesized in the range of 1: 4 to 4: 1. 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 particles is preferably 1.0 ml / g or more, more preferably 1.2 ml / g or more, and more preferably 1.8 ml / g or more in the state before dispersion. More preferably, it is 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. When the pore volume is less than 1.0 ml / g, it is difficult to stain during printing and the water amount latitude is insufficient.

The particle size is preferably substantially 1 μm or less, more preferably 0.5 μm or less, in a state where it 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.
(B) Zeolite particles Zeolite is a crystalline aluminosilicate, which 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:

(MI, MII _1/2 ) _m (Al _m Si _n O _{2 (m + n)} ) · xH ₂ O
Here, MI and MII are exchangeable cations, and MI 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 MII is Ca ²⁺ , Mg ²⁺ , Ba ²⁺ , Sr ²⁺ , C ₈ H ₁₈ N ₂ ^{2+ and the} like. . 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.

The zeolite particles used in the present invention are preferably synthetic zeolites having a stable Al / Si ratio and a relatively sharp particle size distribution. 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 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 size is preferably substantially 1 μm or less, more preferably 0.5 μm or less, in a state where it 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 porous particles are preferably 30 to 95% by mass, more preferably 50 to 90% by mass of the entire hydrophilic layer.
(C) Metal oxide fine particles having an average particle size of 100 nm or less 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. In addition, when these metal oxide fine particles are used together with porous aluminosilicate particles and / or zeolite particles, it is preferable to use the fine particles themselves in a state of negative charge, for example, using alkali colloidal silica. Is preferred. When used together with porous silica particles and porous aluminosilicate particles and / or zeolite particles, for example, it is preferable to use colloidal silica having a surface treated with Al to provide stability in a wide pH range.
(D) Inorganic particles having a new Mohs hardness of 5 or more 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. The average particle diameter is preferably 1 to 2 times the thickness of the hydrophilic layer, more preferably 1.1 to 1.5 times. Further, the particle size distribution is preferably sharp, preferably 60% or more of the whole is contained in the range of 0.8 to 1.2 times the average particle size, and more than 2 times the average particle size. It is preferable that it is 5% or less.

  The thickness of the hydrophilic layer is preferably 0.2 to 10 μm, and more preferably 0.5 to 5 μm. Therefore, the average particle size is preferably 0.2 to 20 μm, and more preferably 0.5 to 10 μm.

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.
(E) Layered mineral particles As layered mineral particles, clay minerals such as kaolinite, halloysite, chrysotile, talc, smectite (montmorillonite, beidellite, hectorite, sabonite, etc.), vermiculite, mica (mica), chlorite and hydrotalc Site, layered polysilicate (kanemite, 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), 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. Among the synthetic fluorine mica, 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.

  The size of the plate-like layered mineral particles is 20 μm or less in average particle size (maximum particle length) in the state of being contained in the hydrophilic layer (including the case where the swelling step and the dispersion peeling step are performed). The average aspect ratio (maximum particle length / particle thickness) is preferably a thin layer of 20 or more, more preferably the average particle size is 10 μm or less, and the average aspect ratio is 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 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 not more than the above range, the flexibility becomes insufficient, and the crack suppressing effect of the coating film is reduced.

The content of the layered mineral particles is preferably 1 to 50% by mass and more preferably 3 to 30% by mass with respect to the entire hydrophilic layer.
(F) Dispersed and crushed porous particles or dispersed and exfoliated layered mineral particles Dispersed crushing or delamination of particles can be roughly classified into dry and wet methods. The dry dispersion crushing does not require a drying process, and thus the process is relatively simple. However, wet dispersion is usually more advantageous for dispersion crushing up to submicron order and delamination up to a layer thickness of 100 nm or less. Examples of the dry dispersion crushing apparatus include a high-speed rotary impact shearing mill (for example, an annular type innomizer), an airflow-type crusher (jet mill), a roll mill, a dry medium agitating mill (for example, a ball mill), and a compression shearing type crusher. (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 size of the porous particles after dispersion and crushing is preferably substantially 1 μm or less, and more preferably 0.5 μm or less. If coarse particles remain, they may be removed by classification or filtration. In addition, the layered mineral particles after dispersion and crushing may be a thin layer having 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 when the particles subjected to dispersion crushing or dispersion peeling are dried, reaggregation may occur. You may perform concentrating or diluting in order to adjust solid content 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 is occurring 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.
(G) Swellable layered mineral particles Swellable synthetic fluorinated mica, which is freely swelled, swells sufficiently only by mixing and stirring with water, and becomes a stable dispersion by dividing into thin layers having an average thickness of 10 nm or less. .

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.
(H) Organic Particles As the organic particles, general crosslinked resin particles such as nylon, PMMA, silicone, Teflon (registered trademark), polyethylene, and polystyrene can be used. In addition, polysaccharides such as mannose, pullulan, alginic acid, dextrin, glucomannan, starch, guar gum, and cellulose derivatives are cross-linked with polyvalent metal ions, general cross-linking agents having glycidyl groups, and cross-linking agents containing formalin. It is also possible to use polysaccharide particles insolubilized in water. These particles may be prepared in advance as an aqueous dispersion, or some dispersion may be contained in the dispersion.

  Among these, Teflon (registered trademark) particles or polysaccharide particles are preferable in consideration of dispersibility in an aqueous coating solution and hydrophilicity of the particles themselves. As the polysaccharide particles, porous polysaccharide particles described in JP-A-10-297078 can be used. Particularly preferred are alginic acid polyvalent metal salt particles obtained by crosslinking alginic acid with polyvalent metal ions. Alginate polyvalent metal salt particles are highly hydrophilic, but have a relatively weak binding force with an inorganic material such as a binder used in the hydrophilic layer of the present invention, such as colloidal silica, and the particle portion can be easily removed. In addition, since the alginate polyvalent metal salt particles obtained as an aqueous dispersion are swollen by water, the particle size shrinks due to drying, but once dried, the particles swell even if dispersed in water again. It is difficult to do. When the alginate polyvalent metal salt particles are used in the present invention, they may be added to the coating solution in a swollen state, or the particles once dried may be redispersed in the coating solution. When used in, it is preferable because voids are formed between the matrix and the hydrophilic layer matrix due to shrinkage during the drying process, and the particles are easily removed by the subsequent treatment.

  In the present invention, the particles having an average particle size of 0.2 to 10 μm contained in the hydrophilic layer preferably include at least one selected from porous inorganic particles, non-porous organic particles, and porous organic particles. Moreover, it is preferable that a porous polysaccharide particle is included as a porous organic particle.

Furthermore, in the process of drying in the coating layer from the state where particles having an average particle size of 0.2 to 10 μm contained in the hydrophilic layer are dispersed in the coating liquid for the hydrophilic layer, the particle size shrinks. It is preferable that Examples of such particles include the swellable layered mineral particles.
(I) Organic binder or organic additive In addition to the above components, the hydrophilic layer may contain an organic binder or additive. As the organic binder, those having hydrophilicity are preferable. For example, proteins such as casein, soybean protein, synthetic protein, chitins, starches, gelatins, alginate, polyvinyl alcohol, silyl-modified polyvinyl alcohol, cation-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, Polyvinyl pyrrolidone etc. are mentioned.

  Further, the hydrophilic layer 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 a hydrophilic layer. Examples of the crosslinking agent include melamine resins, isocyanate compounds, isoxazoles, aldehydes, N-methylol compounds, dioxane derivatives, active vinyl compounds, and active halogen compounds.
(J) Binder of aqueous silicate solution As a binder to be added to the hydrophilic layer, an aqueous silicate solution can also be used. 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 so as to prevent dissolution of inorganic particles.
(K) Inorganic or organic-inorganic hybrid binder by sol-gel method As a binder to be added to the hydrophilic layer, an inorganic polymer or organic-inorganic hybrid polymer by 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 is greatly reduced in hydrophilicity when it is crosslinked to improve durability, water resistance, etc., even if it is a hydrophilic resin. Causes dirt. 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 relative to the entire hydrophilic layer is preferably 0 to 50% by mass ratio, more preferably 1 to 30%, and further preferably 2 to 20%.

  Preferred examples of the hydrophilic layer of the printing plate support of the present invention include a layer coated with a dispersion of zeolite and colloidal silica, a layer coated with a dispersion of porous aluminosilicate and colloidal silica, and a porous aluminosilicate. , A layer coated with a dispersion composed of coidal silica, polyvinyl alcohol, a melamine resin and a reaction accelerator, a layer coated with a Teflon (registered trademark) fine particle dispersion, a layer coated with a calcium alginate fine particle dispersion, and the like. .

The coating amount of the hydrophilic layer is suitably 0.1 to 10 g / m ² , preferably 0.5 to 5 g / m ² after drying / before partial removal treatment. After the dispersion is applied and dried to form a hydrophilic layer, 1) the surface of the hydrophilic layer is wiped with a sponge for plate making, and 2) the adhesive roll is adhered to the surface of the hydrophilic layer and then drawn. 3) Wash with high-pressure water flow, 4) Mount on the plate cylinder of the printing press, attach only the watering roller to the plate, rotate the plate cylinder, or perform normal printing. By removing the portion, it is possible to form a region A having a thickness smaller than the average film thickness at an average pitch of 0.2 to 50 μm.

  Other layers may be formed between the substrate and the hydrophilic layer. For example, there are an undercoat layer that improves the adhesion of the hydrophilic layer, a swell forming layer that imparts a gentle roughness at a long wavelength, and a cushion layer that relieves stress applied to the hydrophilic layer. Any one of these layers may contain a photothermal conversion material.

  In order to produce a printing plate using the printing plate support of the present invention, an ink-receptive image can be formed on the surface of the hydrophilic layer of the support by an inkjet method, a melt thermal transfer method, or the like.

  Examples of the ink jet ink include the following. As an ink receptive material-dispersed aqueous ink, for example, an aqueous solution in which an ink receptive material such as latex fine particles or wax fine particles is dispersed. In order to improve the visibility, pigments and dyes may be contained, and other binders and dispersants may be contained. After forming an image on the support, it can be heated to melt the ink receptive material and penetrate into the porous hydrophilic layer to make a stronger image. Those having a low melt viscosity are preferred. Examples thereof include fine wax particles such as polyethylene, microcrystalline, and carnauba.

  For example, oil-based inks described in the following publications can be used as the oil-based ink. JP-A-10-297083, 10-298472, 10-298473, 10-298479, 10-306244, 10-306245, 10-324833, 10-324834, 10-315617, 10-316916, 10-316917, 10-316920, 11-43638, 11-78226, 11-92705, etc.

  As the hot-melt solid ink, for example, those described in JP-A Nos. 11-139016 and 11-139017 can be used.

  As the thermal melt transfer method, for example, an ink sheet in which a hot melt ink layer is formed on a substrate that absorbs little infrared light is used, and the ink sheet is adhered while the hot melt ink layer and the hydrophilic layer of the ink sheet are in close contact with each other. Infrared laser exposure is performed from the substrate side, and the ink in the exposed portion is melted and transferred to the hydrophilic layer. At this time, the photothermal conversion material may be contained on the hydrophilic layer side (in the hydrophilic layer and / or closer to the substrate than the hydrophilic layer), or on the ink sheet side (the ink layer itself and / or the ink layer). It may be contained in a layer closer to the substrate) or in both.

  Since the image area can be melted and transferred to the inside of the porous hydrophilic layer to make a stronger image, the ink receiving material contained in the ink layer has a low melt viscosity. Preferred are waxes such as polyethylene, microcrystalline, and carnauba.

  Next, a printing plate using the printing plate support of the present invention will be described. This printing plate has at least an image recording layer and a hydrophilic layer on a substrate (support for printing plate). As the image recording layer, an image recording layer in a known CTP printing plate can be applied. Examples of the image recording layer include the following 1) to 3). 1) A layer (ablation layer) in which image-like heating or exposure energy is changed to heat by a photothermal conversion material, and the heat breaks or melts (ablation layer). It is provided between the substrate and the hydrophilic layer. The photothermal conversion material is contained in at least one layer on the side. 2) A layer containing an ink-receptive heat-meltable material, 3) A layer containing an ink-receptive heat-meltable material and a photothermal conversion material.

  As described above, the hydrophilic layer has the region A, preferably, the region A has a pit shape, and the hydrophilic layer contains particles having an average particle size of 0.2 to 10 μm. As described above, the hydrophilic layer contains the particles as means for forming the region A into a pit shape.

  In the printing plate, an image recording layer and a hydrophilic layer are sequentially formed on a substrate, and then the hydrophilic layer is partially removed so that the hydrophilic layer has an average pitch of 1 to 50 μm. Thus, it can be manufactured by a manufacturing method for forming a region having a film thickness thinner than the average film thickness. In addition, after sequentially forming an image recording layer and a hydrophilic layer containing particles having an average particle size of 0.2 to 10 μm on the substrate, a part of the layer containing the particles in the hydrophilic layer is removed. By doing so, a pit shape can be formed on the surface of the hydrophilic layer. For these, the same method as the means for providing the region A of the printing plate support described above can be applied.

  In one form of the method for producing a printing plate, a form in which the step of partially removing the hydrophilic layer is performed after image recording is mentioned. As the form, the form in which the process of removing a hydrophilic layer partially is performed on a printing machine is mentioned. More specifically, the image recording layer of the printing plate having an image recording layer and a hydrophilic layer on the substrate is given imagewise energy of at least one of radiation and heat, and is installed on a printing cylinder of a printing machine, The hydrophilic layer is partially removed by supplying dampening water and / or ink to the hydrophilic layer.

  In the above printing plate, the ink-receptive heat-meltable material contained in the image recording layer is a substance that can form an ink-receptive image portion on the printing plate, and is preferably water-repellent. The softening point is preferably 40 ° C. or higher and 150 ° C. or lower, the melting point 50 ° C. or higher and 200 ° C. or lower, more preferably the softening point 60 ° C. or higher and 100 ° C. or lower, and the melting point 80 ° C. or higher and 150 ° C. or lower. When the softening point is less than 40 ° C. or the melting point is less than 50 ° C., storage stability is a problem, and when the softening point is higher than 150 ° C. or higher than the melting point 200 ° C., the sensitivity is lowered.

  Examples of the water-repellent ink receptive heat-meltable material include paraffin, polyolefin, microwax, fatty acid wax, and oxidized polyethylene wax. These have a molecular weight of about 800 to 10,000, and are usually obtained as low density and high density polyethylene by high pressure and low pressure polymerization methods, or by thermal decomposition of high molecular weight polyolefins. 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. Further, these waxes can be used in combination in order to lower the softening point and improve workability. As the latter, stearamide, linolenamide, laurylamide, myristamide, hardened beef fatty acid amide, palmitoamide, oleic acid amide, rice sugar fatty acid amide, coconut fatty acid amide or methylolated products of these fatty acid amides, methylene bissteraroamide, Ethylene bis-stellaramide etc. are mentioned, These combination is also possible. 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.

  Moreover, as a form of a heat-meltable raw material, it is preferable that it is a particulate form with a particle size of 0.05-10 micrometers. More preferably, it is 0.1-5 micrometers. When the particle size is less than 0.05 μm, the strength of the image forming layer is lowered, the printing durability as a printing plate is lowered, and when it is larger than 10 μm, the resolution is lowered.

  The particulate heat-meltable material, that is, the ink-receiving material particle, may have a continuously changing composition between the inside and the surface layer, or may be coated with a different material. As a coating method, a known microcapsule forming method, a sol-gel method, an electrostatic adsorption method, or the like can be applied.

  In a printing plate having an image recording layer and a hydrophilic layer on a substrate, the hydrophilic layer is an area having an average thickness of 0.2 to 50 μm and being thinner than the average thickness of the hydrophilic layer (A) The image recording layer contains an ink-receptive heat-meltable material, and any layer on the substrate contains a photothermal conversion material, wherein the region (A) has a pit shape The form, the form in which the hydrophilic layer contains particles having an average particle size of 0.2 to 10 μm, and the image recording layer contains a photothermal conversion material, that is, a substance capable of absorbing incident radiation and converting it into heat. The form to do is mentioned.

  As the photothermal conversion material, a function of converting infrared rays into heat, that is, a material having absorption in the near infrared to infrared part can be used. One of them is a general infrared absorbing dye (cyanine, phthalocyanine). However, addition of a water-soluble dye to the layer is not preferable because the water resistance and durability of the entire layer are lowered. In addition, when a water-insoluble dye is added, it is difficult to uniformly disperse the solid dye in the aqueous dispersion in the form of ultrafine particles, and the aggregated dye has poor photothermal conversion efficiency. In addition, it causes stains during printing.

  Among the photothermal conversion materials having absorption in the red exterior, the material itself is preferably a conductive material. It may be a semiconductor. Examples of such materials include metals, conductive carbon, graphite, and conductive metal oxides. Among these, a conductive metal oxide is particularly preferable.

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

As the conductive carbon, furnace black or acetylene black is particularly preferable. The particle size (d ₅₀ ) is preferably 100 nm or less, and more preferably 50 nm or less. Further, the conductivity index represented by the following formula is preferably 30 or more, and more preferably 50 or more.
Conductivity index = {specific surface area (m ² / g) × DBP oil absorption (ml / 100 g)} ^1/2 / (1 + volatile matter)
As the graphite, fine particles having a particle size of 0.5 μm or less, preferably 100 nm or less, more preferably 50 nm or less can be used.

Examples of conductive (or semiconductor) metal oxides include ZnO, Al-doped ZnO, SnO ₂ , Sb-doped SnO ₂ (ATO), Sn-added In ₂ O ₃ (ITO), TiO ₂ , and TiO _2. And TiO (titanium oxynitride, generally titanium black) reduced. Further, it is also possible to use those coated core _{(BaSO 4, TiO 2, 9Al} 2 O 3 2B 2 O, K 2 OnTiO 2 , etc.) in these metal oxides. These particle sizes are 0.5 μm or less, preferably 100 nm or less, and more preferably 50 nm or less. Of these, titanium black is particularly preferred.

  The photothermal conversion material can be contained in any layer formed on the side having the hydrophilic layer on the substrate. These photothermal conversion materials can be used in combination of two or more. In addition, the degree of dispersion in the layer of these light-to-heat conversion materials is closely related to the light-to-heat conversion efficiency, and more highly dispersed increases the calorific value per content of the light-to-heat conversion material. High sensitivity can be achieved with a small addition amount. As a dispersion method, general kneading and dispersion methods can be used, and a dispersant can also be contained.

Further, these photothermal conversion materials can be used by thinly coating the surface of the core material particles. As a coating method, it is possible to coat using a general method for forming microcapsules. For example, various methods described in "Microcapsules-its production, properties, and applications" (1985 Sankyo Publishing Co., Ltd.) written by Tamotsu Kondo and Masumi Koishi can be used. However, it is not limited to this. Among them, the following methods are suitable.
Spray drying method Prepare a dispersion of the photothermal conversion material to be used. A binder and a solvent are appropriately selected. In the dispersing step, usual kneading and dispersing methods can be used. Since only the coating content is dispersed, the efficiency is high, and there is also an advantage that a different material from the binder and solvent required for the layer exhibiting the intended function can be used. For example, the coated particles to be added to the solvent-based coating layer may be prepared with an aqueous dispersion.

The core particles are uniformly suspended in this dispersion and spray-dried to obtain coated particles. This step can be performed using, for example, a commonly used spray-dry granulator. The concentration of the photothermal conversion material dispersion is preferably 0.1 to 10% by mass, and the suspension concentration of the core material particles is preferably 10 to 50% by mass.
Dry method In this method, the core material particles are collided with the coating material, and the coating material is fixed to the surface of the core material by electrostatic force or physical encroachment. In this method, it is preferable that the core particles themselves are not crushed by physical impact, and is particularly suitable when organic particles such as nylon, PMMA, silicone, and Teflon (registered trademark) are used as the core material.

  The coating can be performed using a dispersing machine such as a sand grinder or a ball mill. In addition, it is preferable to use a device such as a hybridizer manufactured by Nara Machinery Co., Ltd., which is a high-speed air-flow impact method that does not use dispersed beads, because the coated particles can be easily recovered. In the case of using dispersed beads (glass, ceramic, etc.), for example, the coating is performed at a rotational speed of 300 to 2000 rpm and a processing time of 5 to 60 minutes. When a hybridizer is used, coating is performed at a peripheral speed of 50 to 150 m / sec and a processing time of 1 to 20 minutes.

  In general, titanium black is difficult to disperse uniformly in the coating solution and requires pre-dispersion such as kneading, but as a core material, organic particles having a diameter of several μm (PMMA, Teflon (registered trademark), Ca alginate, etc.) At the same time, by dispersing in a dry manner, it is thinly fixed / coated on the surface of the core particles by physical encroachment and electrostatic adsorption, and the coated particles themselves can be easily dispersed in the coating solution. A layer having a photothermal conversion function in which titanium black is highly dispersed can be formed.

  When the photothermal conversion material is added to the hydrophilic layer according to the present invention, it is particularly preferable to use a conductive metal oxide. By including a conductive metal oxide in the hydrophilic layer, the polar component in the layer is increased and the hydrophilicity is improved.

  As one form of the above printing plate, the image forming layer is a layer that absorbs infrared rays and partially or entirely destroys it (hereinafter referred to as “ablation layer”), and the hydrophilic layer of the present invention is formed on the layer. The printing plate of the structure which has is mentioned. As such, for example, from a continuous phase such as polyethylene, polypropylene, polyester, polyamide, acrylic resin, vinyl chloride resin, vinylidene chloride resin, polyvinyl butyral resin, nitrocellulose, and a discontinuous phase of a photothermal conversion material such as carbon black. An ablation layer. In this form, the heated upper part melts or softens the upper part of the ablation layer, and at the same time, the upper hydrophilic layer is destroyed and integrated with the upper part of the ablation layer to form an ink-receptive image area. Etc. are typical examples. As the ablation layer, techniques described in JP-A-6-186750, JP-A-6-199064, JP-A-7-314934, JP-A-10-58636, and the like can be applied.

  In an ablation type printing plate, the hydrophilic layer may be partially removed before laser exposure to form a region A, that is, a concave or pit-like roughness, or after laser exposure. The removal treatment may be performed before installation on the printing press, or the removal treatment may be performed on the printing press after the laser exposure.

  Since the ablation layer is destroyed in the laser exposure part (that is, the image part), the hydrophilic layer in the image part is not adhered to the substrate, and the hydrophilic layer is partially removed after the laser exposure. Ink is deposited on either the process or on the printing press at the same time, and a part of the remaining ablation layer, the underlying ink deposition layer, or the substrate surface is used to form an image.

In the case of an ablation type printing plate, the coating amount of the hydrophilic layer is suitably 0.1 to 10 g / m ² , preferably 0.5 to 5 g before drying and partial removal treatment. / M ² .

  As another configuration of the infrared laser exposure CTP printing plate, there is an ink-receptive material leaching type printing plate. The printing plate is a printing plate having an image recording layer containing an ink-receptive heat-meltable material on a substrate and further having a hydrophilic layer of the present invention thereon. In the printing plate, any layer of the photothermal conversion material may be contained, and a layer containing the photothermal conversion material may be further provided between the substrate and the image forming layer.

  The ink-receptive heat-meltable material preferably has a softening point of 40 ° C to 150 ° C, a melting point of 50 ° C to 200 ° C, a softening point of 60 ° C to 100 ° C, and a melting point of 80 ° C to 150 ° C. More preferably it is. When the softening point is less than 40 ° C. or the melting point is less than 50 ° C., storage stability is a problem, and when the softening point is higher than 150 ° C. or higher than the melting point 200 ° C., the sensitivity is lowered.

  Examples of the ink receptive heat-meltable material include paraffin, polyolefin, microcrystalline wax, fatty acid wax, and oxidized polyethylene wax. These have a molecular weight of about 800 to 10,000, and are usually obtained as low density and high density polyethylene by high pressure and low pressure polymerization methods, or by thermal decomposition of high molecular weight polyolefins. 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. Further, these waxes can be used in combination in order to lower the softening point and improve workability. The latter include stearamide, linolenamide, laurylamide, myristylamide, hardened beef fatty acid amide, palmitoamide, oleic acid amide, rice sugar fatty acid amide, coconut fatty acid amide or methylolated products of these fatty acid amides, methylene bisstearamide, ethylene A bisstearoamide etc. are mentioned, These combination is also possible. 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.

  Moreover, as a form of a heat-meltable raw material, it is preferable that it is a 0.05-10 micrometers particulate form. More preferably, it is 0.1-5 micrometers, More preferably, it is 0.2-2 micrometers. If it is less than 0.05 μm, the strength of the image recording layer may be lowered, and there is a concern that the printing durability as a printing plate is lowered. When it is larger than 10 μm, the resolution is lowered. Moreover, the composition of the inside and the surface layer of the heat-meltable material 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. The coating amount of the hydrophilic layer, before performing the dried / partial removal processing is 0.1-5 g / m ^2, preferably, is 0.2 to 3 g / m ^2.

  Further, the thickness of the thin region after the partial removal treatment of the hydrophilic layer is preferably 0.5 μm or less at the thinnest portion (for example, at the bottom portion of the pit shape), The thickness is more preferably 0.3 μm or less, and further preferably 0.2 μm or less.

In addition to the above, the image recording layer of the printing plate of the present invention may contain additives used for the image recording layer in known CTP printing plates.
《Matters other than constituent requirements described in claims》
In the printing plate, a protective layer may be further provided on the hydrophilic layer for the purpose of preventing scratches and improving handleability. The protective layer may be of a type in which a sheet is bonded and peeled at the time of printing, or may contain a water-soluble resin or the like and be removed at the time of printing. Further, a back coat layer may be provided on the back surface of the substrate.

  In the production of the printing plate, a general coating method can be used to provide an image recording layer on a substrate. When applying and drying the layer containing the heat-melting material, and when coating and drying other layers after the layer containing the heat-melting material is formed on the substrate, dry it at a temperature below the melting point of the heat-melting material. In the case of drying at a temperature higher than the melting point, drying in a short time of 1 minute or less is preferable. Moreover, an aging process can also be suitably performed after application | coating drying. The aging treatment is preferably performed in a dry atmosphere at 40 to 70 ° C. for 6 to 200 hours.

  As a printing plate for infrared exposure CTP, a material showing exposure visible image quality can be added to any layer. For example, a known technique used for thermal paper can be applied. Moreover, you may provide the distinguishability of an exposed part and an unexposed part by changing the light transmittance and light-scattering property of a layer by exposure heating.

The imagewise exposure of the printing plate of the present invention is preferably performed by a near infrared laser (800 to 850 nm). As an exposure means, a general exposure machine for thermal CTP can be used. The exposure energy is preferably 100 to 500 mJ / cm ² .

Preparation of Coating Liquid A dispersion liquid was prepared under the composition and dispersion conditions shown in Tables 1 to 5, and filtered to obtain a hydrophilic layer coating liquid 1-1 to 1-14 and an image recording layer coating liquid for an ablation layer. Coating liquids 2-1 to 2-3 and coating liquids 3-1 to 3-6 for the hot-melt material-containing layer were prepared.

Preparation of substrate 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
The aluminum base material degreased in the same manner as the Al base material 1 was anodized at a voltage of 20 V at 25 ° C. using a 20 mass% sulfuric acid aqueous solution to form an anodized film of 0.5 g / m ² . 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 . Next, using a 1% by mass aqueous sodium hydroxide solution, it was immersed at 30 ° C. for 20 seconds, washed with water, and then subjected to anodic oxidation treatment and sodium silicate treatment in the same manner as the Al substrate 2.
Al base 4
An organic-inorganic sol-gel film was formed on the surface of an aluminum base material on which an anodic oxide film was formed in the same manner as the Al base material 2 by the same method as described in Example 1 of JP-A-8-240914.
Formation of PET base primer layer A PET base material was formed by forming a two-layer primer layer on a polyethylene terephthalate (PET) film having a thickness of 0.18 mm by the following method.
First undercoat layer After the corona discharge treatment was applied to the coated surface of the PET base material, the coating liquid having the following composition was dried at a temperature of 20 ° C. and a relative humidity of 55% with a wire bar to a film thickness of 0.4 μm. It was applied so that it was dried at 140 ° C. for 2 minutes.
<First undercoat layer coating solution composition>
Acrylic latex particles (n-butyl acrylate / t-butyl acrylate / styrene / hydroxyethyl methacrylate = 28/22/25/25)
(Mol%) 36.9 g
Surfactant (A) 0.36g
Hardener (a) 0.98g
Distilled water was added to the above to make 1000 ml, and a coating solution was obtained.
Second undercoat layer The surface of the above-mentioned film on which the first undercoat layer has been formed is subjected to corona discharge treatment, and then the coating liquid having the following composition is dried by an air knife method in an atmosphere of 35 ° C. and a relative humidity of 22%. It was applied so that the thickness was 0.1 μm. Thereafter, drying was performed at 140 ° C. for 2 minutes.
<Coating solution composition for second undercoat layer>
9.6 g of gelatin
Surfactant (A) 0.4g
Hardener (b) 0.1g
Distilled water was added to the above to make 1000 ml, and a coating solution was obtained.

Examples 1-1 to 1-16, Comparative Examples 1-1 to 1-7
The samples according to the present invention are Examples 1-1, 1-5 to 1-7, 1-15, and 1-16.
Preparation of printing plate support On the substrates shown in Tables 6 to 8, the hydrophilic layer coating solution shown in the same table was applied using a wire bar so as to have the coating amount shown in the same table, and 80 ° C. And then aging was performed for 48 hours under conditions of a relative humidity of 30% and 55 ° C. After that, those with “Yes” in the column of “Partial removal treatment of hydrophilic layer” in the same table are rubbed with a sponge for plate making while applying running water (° C.) to the hydrophilic layer surface. The layer was partially removed, and the surface of the hydrophilic layer was thoroughly washed with pure water, and then dried at 80 ° C. for 3 minutes to obtain a printing plate support. In addition, what is described as “none” was used as a printing plate support without the partial removal treatment.
Surface shape observation About each said support body, the surface was measured using the non-contact three-dimensional surface roughness meter (RST Plus made from WYKO). Tables 6 to 8 show the measured surface shape roughness Ra. The measurement was performed in the VSI mode, and measurement was performed at five locations for each sample at a magnification of 40 times, and the average value was described for the roughness parameter. In the measurement, the sample surface was subjected to a vapor deposition treatment with platinum palladium to a thickness of 15 nm.
Production of Printing Plate Using the image forming inks shown in Tables 6 to 8, printing plates on which an image was formed by an inkjet method were produced. Table 9 shows the ink composition used in the ink jet system.

The ink of composition [1] was recorded by an ink jet printer for water-based ink, and the ink of composition [2] was recorded by an ink jet printer for solid ink. For the printing plate using the ink of composition [1], an image was formed, followed by heat treatment at 90 ° C. for 5 minutes. Using these printing plates, printing was performed by the following printing method, and printability and image strength were measured. The results are shown in Tables 6-8.
Printing method: DAIYA1F-1 manufactured by Mitsubishi Heavy Industries, Ltd. is used as a printing machine, coated paper, dampening water (concentration of H liquid SG-51 manufactured by Tokyo Ink Co., Ltd., 1.5%) and ink (Toyo Ink Co., Ltd.) Printing was performed using Toyo King Hi-Echo M Red).
Printing suitability (difficulty in generating scumming): The difficulty in generating scumming when the dampening water supply amount was reduced was evaluated.
Printability (stain recovery property): After printing 1000 sheets, the supply of dampening water was cut off, only ink was applied to the entire printing plate, dampening water was supplied again, and printing was resumed. The degree of smearing on the non-image area of the paper was evaluated by the number of printed sheets with the same level as when 1000 sheets were printed.
Printability (Blanket stain): The portion corresponding to the non-image area on the blanket after printing 1000 sheets was peeled off with a transparent adhesive tape, and then applied to a blank sheet, and the reflection density was measured. The numerical values shown in Tables 6 to 8 are numerical values obtained by subtracting the density of the blank paper from the measured value of the blanket stain density.
Image intensity: The number of printed sheets at which a small dot portion of an image starts to be evaluated was evaluated.

The SEM photograph of the hydrophilic layer surface on which the region A of the printing plate support of Example 1-12 was formed is shown in FIGS. 1 and 2, and the SEM photograph of the hydrophilic layer surface before the region A is formed is FIG. 4 shows.
Examples 2-1 to 2-11, Comparative Examples 2-1 to 2-5
The sample according to the present invention is Example 2-10.
Preparation of Printing Plate On the base materials shown in Tables 10 to 12, an ablation layer and a hydrophilic layer described in the same table as an image forming layer were provided in this order. Each of these layers was applied using a wire bar so as to have the coating amount shown in the table, then dried at 70 ° C. for 5 minutes, and aged for 48 hours under conditions of 30% relative humidity and 55 ° C. Then, what is described as “Yes” in the column of “Partial removal treatment of hydrophilic layer” in Tables 10 to 12 is rubbed with a sponge for making a plate while running water on the surface of the hydrophilic layer. The layer is partially removed, and the surface of the hydrophilic layer is thoroughly washed with pure water, and then dried at 70 ° C. for 5 minutes to produce a printing plate material. The resulting printing plate is used with the image forming layer outside. Then, it was wound around a drum of a laser exposure machine, and was exposed imagewise with a 830 nm infrared laser at a resolution of 4000 dpi (laser beam diameter 6 μm) with an exposure energy amount of 400 mj / cm ² to obtain a printing plate. On the other hand, what is described as “none” is a printing plate that is not subjected to the above partial removal treatment, and this printing plate is exposed imagewise under the same conditions as described above, and then the surface of the hydrophilic layer is washed with water. The hydrophilic layer was partially removed by rubbing with a plate-making sponge while applying, and the surface of the hydrophilic layer was thoroughly washed with pure water, followed by drying at 70 ° C. for 5 minutes to prepare a printing plate.
Surface shape evaluation About each said printing plate, the surface of the non-image part was measured by the method similar to Example 1. FIG. The observed surface shapes are shown in Tables 10 to 12. Further, the printability of the printing plate was measured and evaluated in the same manner as in Example 1. The results are shown in Tables 10 to 12.

Examples 3-1 to 3-11, comparative examples 3-1 to 3-5
The sample according to the present invention is Example 3-6.
Preparation of Printing Plate On the substrates shown in Tables 13 to 15, coating solutions for the photothermal conversion layer, the heat-melting material-containing layer, and the hydrophilic layer described in the same table as the image forming layer were applied in this order. Each of these coating solutions was applied using a wire bar so as to have the coating amount shown in the table, and then dried at 70 ° C. for 5 minutes. The obtained printing plate was aged for 48 hours under conditions of a relative humidity of 30% and 55 ° C. After that, what is described as “Yes” in the column of “Partial removal treatment of hydrophilic layer” in the same table is rubbed with a plate-making sponge while running water on the hydrophilic layer surface, The surface of the hydrophilic layer is thoroughly washed with pure water, dried at 70 ° C. for 5 minutes to prepare a printing plate, and the resulting printing plate is exposed to laser with the image forming layer facing outside. A printing plate was obtained by wrapping around a drum of the machine and exposing it imagewise with an 830 nm infrared laser at a resolution of 4000 dpi (laser beam diameter 6 μm) while changing the exposure energy as described in Tables 13-15. . In addition, what is described as “none” is a printing plate that is not subjected to the above partial removal treatment, and this printing plate is exposed imagewise in the same manner as described above, and then the surface of the hydrophilic layer is washed with water. The surface of the hydrophilic layer was thoroughly removed with pure water and then dried at 70 ° C. for 5 minutes to obtain a printing plate.

About each said printing plate, the surface of the non-image part part before and behind printing evaluation was measured by the method similar to Example 1. FIG. The observed surface shapes are shown in Table 13 to Table 15. Further, the sensitivity of the above printing plate was evaluated by the following method, and the printability was measured and evaluated in the same manner as in Example 1. The results are shown in Tables 13-15.
Sensitivity evaluation method: Sensitivity was defined as the lowest exposure energy amount at which a good print image without fading was obtained by visual judgment.

It is a SEM photograph of the hydrophilic layer surface in which the area | region A of the support for printing plates of Example 1-12 was formed. It is a SEM photograph (higher magnification than FIG. 1) of the hydrophilic layer surface which formed the area | region A of the support for printing plates of Example 1-12. It is a SEM photograph of the hydrophilic layer surface before forming area | region A of the support body for printing plates of Example 1-12. It is a SEM photograph (higher magnification than FIG. 3) of the hydrophilic layer surface before forming the area | region A of the support body for printing plates of Example 1-12.

Claims (3)

In the method for producing a support for a printing plate having a hydrophilic layer on a substrate, the hydrophilic layer is averaged by partially removing the hydrophilic layer after forming the hydrophilic layer on the substrate. And a hydrophilic layer having a region having a pit shape whose thickness is thinner than the average thickness at a pitch of 0.2 to 50 μm. After forming the image recording layer and the hydrophilic layer in this order on the substrate, the hydrophilic layer is partially removed, so that the hydrophilic layer has an average film thickness at an average pitch of 0.2 to 50 μm. A method for producing a support for a printing plate, comprising a hydrophilic layer having a pit shape with a thinner film thickness. A hydrophilic layer having a region having a pit shape having a thickness smaller than the average film thickness at an average pitch of 0.2 to 50 μm, obtained by the method for producing a printing plate support according to claim 1. A support for a printing plate, comprising:

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