JPH1152580A - Planographic printing plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a planographic printing plate having high ink repellency, ensuring a wide acceptable range of dampening water and having high durability in printing by containing titanium dioxide whose surface is made hydrophilic into a hydrophilic swellable layer. SOLUTION: The planographic printing plate has at least a hydrophilic swellable layer on the substrate and the hydrophilic swellable layer contains titanium dioxide whose surface is made hydrophilic. The titanium dioxide is titanium dioxide granulated by a sulfuric acid method, a chlorine method, etc., or titanium dioxide produced by pulverizing and classifying the granulated titanium dioxide. Specifically, the titanium dioxide is, e.g., anatase type or rutile type titanium dioxide. The pref. average primary particle diameter of the titanium dioxide is 0.005-5 μm, in particular 0.007-1 μm. The pref. amt. of the titanium dioxide is 5-60 pts.wt., in particular 10-40 pts.wt., based on 100 pts.wt. solid content of the hydrophilic swellable layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lithographic printing plate, and more particularly to a novel lithographic printing plate having high ink repellency without desensitizing treatment and having a wide control range of dampening solution. is there.

[0002]

2. Description of the Related Art Conventionally, as a plate to be used for lithographic printing, a lipophilic photosensitive layer is applied on an aluminum substrate which has been subjected to a hydrophilic treatment, and the photosensitive layer remains on the image portion by a photolithography technique. In the image area, the surface of the aluminum substrate is exposed, a PS plate with water that forms an ink image by forming a dampening solution layer on the surface and repelling the ink, and a silicone rubber layer instead of the dampening solution Is used as an ink repellent layer, that is, a waterless PS plate, a so-called waterless lithographic plate.

[0003] The PS plate with water is a printing plate excellent in practical use. Usually, grained aluminum is used for the support, and a treatment such as anodizing the surface of the grain is performed as necessary. The improvement in the water retention of the dampening solution and the adhesion to the photosensitive layer are reinforced. The aluminum surface is generally subjected to a chemical treatment such as zirconium fluoride or sodium silicate in order to obtain storage stability of the photosensitive layer.

The PS plate with water is widely used because of its excellent printing characteristics such as printing durability and image reproducibility. On the other hand, the PS plate with water has a complicated manufacturing process as described above. , Its simplification is desired.

[0005] As a simple form of the PS plate with water,
An image receiving layer such as toner is formed on a support such as paper, an image is formed using electrophotographic technology, and the non-image area is desensitized with an etchant to convert the image receiving layer into an ink repellent layer. Direct-drawing lithographic printing plate precursors to be used are widely used in practice. Specifically, an image-receiving layer comprising a water-soluble binder polymer, an inorganic pigment, a water-proofing agent and the like is generally provided on a water-resistant support, and US Pat.
865, JP-B-40-23581, JP-A-48-9802, JP-A-57-205196, JP-A-60-2309, and JP-A-57-17.
No. 91, JP-A-57-15998 and JP-A-5
JP-A-7-96900, JP-A-57-205196, JP-A-63-166590, JP-A-63-1
No. 66591, JP-A-63-317388,
JP-A-1-114488 and JP-A-4-367
No. 868, and the like. These direct-drawing lithographic printing plate precursors include PVA, starch, hydroxyethyl cellulose, casein, gelatin, polyvinylpyrrolidone, vinyl acetate-crotonic acid copolymer and styrene-maleic acid copolymer as an image receiving layer to be converted into an ink repellent layer. Water-soluble binder polymer that exhibits hydrophilicity before desensitization treatment such as coalescence, water-dispersible polymer such as acrylic resin emulsion, inorganic pigment such as silica or calcium carbonate, and melamine / formaldehyde resin condensate Those composed of a waterproofing agent as described above have been proposed.

[0006] Any of these direct-drawing lithographic printing plate precursors requires a desensitizing treatment in order to convert the image receiving layer into an ink repellent layer, and shows almost no ink repellency without the desensitizing treatment. In addition, it was necessary to use a special chemical as a fountain solution during printing.

Further, in the case of a PS plate with water, it is necessary to constantly control the amount of dampening solution at the time of printing, and considerable skill and experience have been required to properly control the dampening solution. IPA added as an essential component to the fountain solution
In recent years, the use of (isopropanol) has been strictly regulated from the standpoint of the occupational health environment and wastewater treatment, and countermeasures are urgently needed. Also, JP-A-8-282142
JP-A-8-283144 and JP-A-8-283144
Japanese Patent No. 292558 discloses a lithographic printing plate having a hydrophilic swelling layer and having good ink repellency, but a lithographic plate having more excellent ink repellency, a dampening water tolerance and an ink filling property. There is a need for printing plate materials.

Further, JP-A-5-19460 discloses a lithographic printing plate in which fine particles such as colloidal silica and titanium dioxide are added to a hydrophilic layer. This is composed of a hydrophilic layer obtained by solidifying fine particles that are the main component with a binder resin such as polyvinyl alcohol or a cross-linking agent. It was a lithographic printing plate that supplemented the water retention capacity of polyvinyl alcohol. As a result, the hydrophilic layer itself is hard and has substantially no water swelling property. As a result, the ink repellency and the fountain solution tolerance are not always good, and the printing durability is also poor.

[0009]

DISCLOSURE OF THE INVENTION The present inventors have high ink repellency without performing desensitization treatment, have a wide tolerance of dampening solution, and can eliminate IPA without dampening solution. A new lithographic printing plate with excellent ink repellency and high printing durability has been intensively studied, and as a result, the intended purpose can be realized by introducing specific fine particles into the hydrophilic swelling layer. And arrived at the present invention.

An object of the present invention is to provide a novel lithographic printing plate which has high ink repellency without desensitizing treatment, has a wide allowable range of dampening solution, and can eliminate IPA of dampening solution. In other words, it is an object of the present invention to provide a lithographic printing plate which is more excellent in ink resilience and has high printing durability.

[0011]

Means for Solving the Problems The present invention is intended to achieve the purpose of nutritional printing, and the lithographic printing plate of the present invention is a lithographic printing plate having at least a hydrophilic swelling layer on a substrate. The hydrophilic swelling layer is characterized by containing a surface-hydrophilized titanium oxide, and in the present invention, based on 100 parts by weight of the solid content of the hydrophilic swelling layer,
Titanium oxide having an average primary particle diameter of 0.005 to 5 μm
It is included as a preferred embodiment that the content is contained in an amount of 60 parts by weight.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention is characterized in that a hydrophilic swelling layer contains titanium oxide subjected to a surface hydrophilization treatment. The hydrophilic swelling layer contains the surface-hydrophilized titanium oxide, so that the ink resilience is more excellent, not only the fountain solution tolerance becomes wider, but also the inking property of the image area becomes higher. And other effects,
The reason is not always clear. However, when fountain solution is supplied during printing, the hydrophilic swelling layer largely swells as a whole in the hydrophilic swelling layer, but when viewed in detail, there is a portion that does not substantially swell in the hydrophilic swelling layer. Think important. In other words, the fact that the size of such a portion that does not substantially swell is an appropriate size contributes to the expression of the above-described effects on the ink resilience, the fountain solution allowable width and the ink inking property, and at the same time, It is presumed that good wetting and adhesion at the interface between the swelling portion and the titanium oxide are important from the viewpoint of printing durability.

The titanium oxide used in the present invention includes:
Titanium oxide granulated by a sulfuric acid method, a chlorine method, or the like, itself or a titanium oxide produced by pulverizing and classifying,
Specific examples include anatase type titanium oxide and rutile type titanium oxide.

The average primary particle size of the titanium oxide used in the present invention is preferably from 0.005 to 5 μm, more preferably from 0.007 to 1 μm. Average primary particle size is 5μ
If it is larger than m, not only the effect of improving the ink resilience and expanding the allowable range of dampening solution is not seen, but also it is difficult to reproduce fine halftone dots at the time of image formation, which leads to a decrease in resolution. The rubbing strength of the plate surface is reduced, possibly due to insufficient wetting / adhesion at the interface between the water-swelling portion and the fine particles, and the printing durability tends to be greatly reduced. On the other hand, if the average primary particle diameter is smaller than 0.005, the effect of improving the ink resilience, expanding the permissible fountain solution, and improving the ink adhesion is probably because the size of the portion that does not swell in water is too small. Tend to disappear.

The titanium oxide used in the present invention preferably has an average primary particle diameter calculated according to the following method within a specific range.

D ₁ = Σ _n D / Σ _n D ₁ : average primary particle diameter Σ _n D: sum of diameters of all particles Σ _n : total number of particles [Measurement method of average primary particle diameter] It is sprayed on a copper plate, and a vapor deposition film of carbon and copper is sequentially provided.
This is placed on a sample stage, enlarged to a specific magnification by an electron microscope, and a micrograph is taken. To directed diameter of the fine particles in the micrograph was measured for 300-400 pieces (sigma _n) obtaining a sigma _n D.

The content of titanium oxide used in the present invention is 5 to 5 parts by weight of the solid content of the hydrophilic swelling layer.
Preferably, it is 60 parts by weight. More preferably 10
４０40 parts by weight. If the content of titanium oxide is less than 5 parts by weight, the effect of improving the ink repulsion, expanding the permissible range of dampening solution, and improving the ink adhesion may be because the area of the portion that does not swell in water is too small. Tend to disappear. When the content of titanium oxide is more than 60 parts by weight, the water swelling ratio of the hydrophilic swelling layer is reduced, and excellent properties such as a high ink repellency inherent in the hydrophilic swelling layer and a wide allowable range of fountain solution are provided. Tend to not be obtained.

The hydrophilic swelling layer of the present invention swells by containing fountain solution in the layer, and the hydrophilic swelling layer itself has rubber elasticity. Therefore, it is considered that the hydrophilic swelling layer not only functions as an ink repellent layer, but also serves as a cushion in displacing the ink on the plate surface to the printing medium, so that a high-quality printed material can be obtained. . In addition, it is presumed that it is important that the rubber elasticity of the hydrophilic swelling layer changes depending on the amount of water contained in the hydrophilic swelling layer. That is, dampening water is supplied to the plate surface, the hydrophilic swelling layer is wetted, oil-based ink is deposited on the plate surface, and the ink-attached surface of the plate is pressed against the printing medium,
In a series of cycles of displacing the oil-based ink to the printing medium, dampening water is supplied, and when the hydrophilic swelling layer swells most, the rubber elasticity is large, and the plate surface is pressed against the printing medium and the hydrophilic swelling layer is pressed. When water is extruded from the water, the amount of water contained in the hydrophilic swelling layer decreases, and the rubber elasticity decreases. Therefore, it is considered that the point at which the plate surface contacts the print medium relatively softly in the initial stage of the press-bonding to the printing medium and relatively firmly in the latter half of the press-bonding strongly affects the image quality.

In the present invention, by adding the surface-treated titanium oxide to the hydrophilic swelling layer, an ink image having a high printing density can be obtained without losing water even when the dampening water supply amount is large. Is obtained.

In the present invention, the hydrophilization treatment of titanium oxide means that titanium oxide does not settle in water or an organic solvent miscible with water at an arbitrary ratio regardless of the passage of time. Or dispersed in a state close to temporary particles,
Means to be retained.

Specific methods for hydrophilizing fine particles include (1) a method of providing a hydrophilic group (hydroxyl group, carboxyl group, amino group, etc.) on the surface of the fine particles, and (2) water or an arbitrary ratio to water. A method in which a wetting dispersant is added to an organic solvent miscible with the above, and the surface of the fine particles is wetted with the solvent, and then a binder polymer is added to disperse the surface of the fine particles in the binder polymer. Using a polymer having a binder polymer,
And (4) a method in which a functional group on the surface of the fine particles is reacted with a binder polymer or a crosslinking agent capable of reacting with the binder polymer to form a chemical bond between the fine particles and the binder polymer. These methods (1) to (4) can be used alone or in combination of two or more methods.

In the present invention, a wetting and dispersing agent is preferably used. Examples of the wetting and dispersing agent include sodium dialkyl sulfosuccinate, surfactants such as fluorine-based surfactants and low molecular weight surfactants, inorganic salts such as polyphosphates, formalin condensates of naphthalene sulfonates, and polystyrene sulfonic acid. Examples thereof include a salt, a polyacrylate, a salt of a copolymer of a vinyl monomer and a carboxylic acid monomer, or a polymer dispersant such as carboxymethyl cellulose or polyvinyl alcohol.

Among these, it is also a preferred embodiment to use the polymer type dispersant itself as the hydrophilic polymer constituting the hydrophilic swelling layer. Specifically, a binder polymer having an acrylic acid unit, a methacrylic acid unit, an acrylate unit or a methacrylate unit, and / or a vinyl alcohol unit as a constituent unit is particularly preferable. When a polymer having a chemical structure having such a wet dispersion effect is used as a binder polymer, the surface of the fine particles is treated in advance with a small amount of a binder polymer solution or aqueous solution, and then the remaining binder polymer is added and mixed. The fine particles may be mixed and stirred with the binder polymer solution or the aqueous solution from the beginning.

Further, in the present invention, the crosslinking agent capable of crosslinking with the inner polymer or the binder polymer has a reactive functional group such as a hydroxyl group, a carboxyl group, an aldehyde group, an isocyanate group, or an epoxy group, A method of dispersing and stabilizing the dispersion by bonding with a group through a chemical bond is also preferably used.

When strong agitation or shaking is required for performing such a hydrophilic treatment, for example, a ball mill,
Equipment such as a homogenizer, a super mill, a three-roll, a twin-screw mixer, a mixing roll, a planetary mixer, a kneader, an attritor, a universal mill, and the like can be used.

Further, as a hydrophilizing treatment of the fine particles, a solution or an aqueous solution of the hydrophilizing agent is atomized, and the fine particles are passed through the atmosphere to uniformly adhere or react the hydrophilizing agent on the surface of the fine particles. A so-called spray dryer system is also preferably used.

In the present invention, titanium oxide may be used alone, or two or more types of titanium oxide having different types and particle diameters may be used in combination. In addition, inorganic fine particles, organic fine particles,
It can be used in combination with inorganic-organic composite fine particles.

The non-image area of the lithographic printing plate according to the present invention comprises a hydrophilic swelling layer. Next, such a hydrophilic swelling layer will be described.

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

As used herein, the term “hydrophilic polymer” refers to a known water-soluble polymer (which means completely soluble in water) or a pseudo-water-soluble polymer (which means amphipathic. Means water-swellable polymer (means that swells in water but does not dissolve). That is, it refers to a polymer that adsorbs or absorbs water under normal use conditions, and a polymer that dissolves in or swells in water.

In the present invention, known hydrophilic polymers can be used, including animal-based polymers,
There are vegetable and synthetic polymers. For example, "Fu
Nectical Monomers "(Y. Nyqu
ist, Dekker), "Water-soluble polymer" (Nakamura, Chemical Industry Co., Ltd.), "Latest processing / modification technology and application development of water-soluble polymer water-dispersed resin, Comprehensive technical materials" (Management Development Center publication) Section), "Applications and Markets of New Water-Soluble Polymers" (CMC) and the like. A specific example will be described below.

(A) Natural polymers: starch-acrylonitrile-based graft polymer hydrolyzate, starch-acrylic acid-based graft polymer, starch-styrene sulfonic acid-based graft polymer, starch-
Vinyl sulfonic acid type graft polymer, starch-acrylamide type graft polymer, carboxylated methyl cellulose, methyl cellulose, hydroxypropyl methyl cellulose, hydroxyethyl cellulose, xanthate cellulose, cellulose-acrylonitrile type graft polymer, cellulose-styrene sulfonic acid type graft polymer , A carboxymethylcellulose-based crosslinked product,
Hyaluronic acid, agarose, collagen, milk casein, acid casein, rennet gasein, ammonia casein, potashized casein, borate casein, glue, gelatin, gluten, soy protein, alginate, ammonium alginate, potassium alginate, sodium alginate Gum, tragacanth gum, karaya gum, guar gum, locust bean gum, Irish moss, soy lecithin, pectic acid, starch, carboxylated starch, agar, dextrin, mannan, etc.

(B) Synthetic polymers polyvinyl alcohol, polyethylene oxide, poly (ethylene oxide-CO-propylene oxide), aqueous urethane resin, water-soluble polyester, ammonium polyacrylate, sodium polyacrylate, polyammonium methacrylate, N-vinylcarboxylic acid-based polymer, acrylic acid-based copolymer, acrylic emulsion copolymer, polyvinyl alcohol-based crosslinked polymer, sodium polyacrylate-based crosslinked product, saponified polyacrylonitrile-based polymer, hydroxyethyl acrylate-based polymer, hydroxyethyl methacrylate Polymer, poly (vinyl methyl ether-CO-maleic anhydride), maleic anhydride copolymer, vinylpyrrolidone copolymer, polyethylene glycol diacrylate Crosslinked polymers, polyethylene glycol dimethacrylate-based crosslinked polymers, polypropylene glycol diacrylate-based crosslinked polymers, and polypropylene glycol dimethacrylate-based crosslinked polymers.

The above hydrophilic compound may contain monomers or copolymer components having different substituents for the purpose of imparting flexibility or controlling hydrophilicity as long as the effects of the present invention are not changed. It is.

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

The hydrophilic swelling layer is formed by crosslinking or pseudo-crosslinking at least one of the above hydrophilic polymers as necessary.
A layer can be formed on a substrate by insolubilizing in water. Usually, the cross-linking reaction is performed by performing a three-dimensional cross-linking reaction using a reactive functional group of the hydrophilic polymer. The cross-linking reaction may be covalent cross-linking or ionic cross-linking.

Examples of the compound used in the crosslinking reaction include known polyfunctional compounds having a crosslinking property, such as polyepoxy compounds, polyisocyanate compounds, polyacryl compounds, polymethacryl compounds, polymercapto compounds, and polyalkoxysilyl compounds. Examples include compounds, polyvalent metal salt compounds, polyamine compounds, aldehyde compounds, and polyvinyl compounds. The crosslinking reaction is carried out by adding a known catalyst to accelerate the reaction.

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

The hydrophilic swelling layer may be provided with various heat histories by applying a heat treatment or the like during or after the application. In this case, even if the constituent components of the hydrophilic swelling layer are the same, water swelling properties such as water absorption and water absorption may change due to the heat history.

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

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

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

The water absorption of the non-image area composed of the hydrophilic swelling layer of the present invention is 1 from the viewpoint of ink repulsion and form retention.
５０50 g / m ² , preferably 2-40 g / m ²
m ² , more preferably 3 to 30 g / m ² .

The hydrophilic swelling layer of the present invention preferably has a water absorption value measured according to the following definition within a specific range.

Water absorption (%) = water absorption (g / m ² ) / hydrophilic swelling layer thickness (g / m ² ) × 100 where the hydrophilic swelling layer thickness was applied on the substrate. The value refers to a value measured by a gravimetric method after the coating layer of the hydrophilic swelling layer corresponding to the non-image area of the dried lithographic printing plate is peeled off. The thickness of the hydrophilic swelling layer was measured according to the following equation.

The thickness of the hydrophilic swelling layer (g / m ² ) = (W−W ₀ ) / α W: the dry weight (g) of the lithographic printing plate obtained by cutting the portion formed only from the non-image area W ₀ : Dry weight after peeling off the hydrophilic swelling layer from W (g) α: Measurement area of lithographic printing plate (m ² ) [Method for measuring hydrophilic swelling layer thickness] Lithographic printing plate to be measured Is defined as a predetermined area α
After drying in an oven at 60 ° C. for 30 minutes,
The dry weight W is weighed. Thereafter, the lithographic printing plate is immersed in purified water to swell the hydrophilic swelling layer, and the swelling layer is peeled off using a screver or the like. The lithographic printing plate from which the hydrophilic swelling layer has been peeled off is again dried in a 60 ° C. oven for 30 minutes, and its dry weight W ₀ is weighed.

The water absorption of the non-image area (ink repellent portion) comprising the hydrophilic swelling layer of the present invention is preferably from 10 to 2000%, and more preferably from 50 to 1700%, from the viewpoint of ink repulsion and form retention. And more preferably in the range of 50 to 700%. When the water absorption is less than 10%, the ink repellency of the non-image area is reduced. On the other hand, when the water absorption of the non-image area is more than 2000%, the non-image area has low shape retention, so that the non-image area has a low shape retention. The image area tends to be easily damaged.

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

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

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

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

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

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

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

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

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

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

Next, an example of the method for producing a lithographic printing plate according to the present invention will be described, but the present invention is not limited to this.

The image of the lithographic printing plate of the present invention can be formed, for example, by irradiating the surface of a lithographic printing plate precursor having a hydrophilic swelling layer on a substrate with actinic rays.
The actinic rays referred to here are high-pressure mercury lamps, carbon arc lamps, xenon lamps, metal halide lamps, ultraviolet light to visible light such as fluorescent lamps, semiconductor lasers, YAG lasers, argon ion lasers, helium neon lasers, helium cadmium lasers, Refers to visible light to infrared light such as carbon dioxide lasers and light emitting diodes.

For such image formation, known photosensitive compounds are used. Examples of known photocrosslinkable or photocurable photosensitive compounds include the following specific examples (1) to (5).

(1) Photopolymerizable monomer or oligomer alcohols (ethanol, propanol, hexanol, octanol, cyclohexanol, glycerin,
Acrylic ester or methacrylic acid of trimethylolpropane, pentaerythritol, isoamyl alcohol, lauryl alcohol, stearyl alcohol, butoxyethyl alcohol, ethoxyethylene glycol, methoxyethylene glycol, methoxypropylene glycol, phenoxyethanol, phenoxydiethylene glycol, tetrahydrofurfuryl alcohol, etc. Addition reaction products of acid esters, carboxylic acids (acetic acid, propionic acid, benzoic acid, acrylic acid, methacrylic acid, succinic acid, maleic acid, phthalic acid, tartaric acid, citric acid, etc.) with glycidyl acrylate or glycidyl methacrylate; Addition reaction product of m-xylylenediamine, benzylamine and glycidyl acrylate or glycidyl methacrylate And addition reaction products of Le acid or methacrylic acid.

(2) Photodimerizable photosensitive composition A photosensitive layer containing, for example, polyvinyl cinnamate, such as p
A 1: 1 polycondensation unsaturated polyester of phenylenediacrylic acid and 1,4-dihydroxyethyloxycyclohexane, a photosensitive polyester derived from cinnamylidenemalonic acid and difunctional glycols, polyvinyl alcohol, starch, cellulose And cinnamic acid esters of hydroxyl-containing polymers such as.

(3) A composition comprising a combination of a monomer, oligomer or polymer having an epoxy group and a known photoacid generator. When exposed to light, the photoacid generator generates a Lewis acid or a Bronsted acid, Crosslinks by cationic polymerization.

(4) Composition of monomer, oligomer or polymer having an allyl group and / or a vinyl group and monomer, oligomer or polymer having a mercapto group. When exposed, the mercapto group is added to the allyl group and / or the vinyl group. And crosslink.

(5) Composition of a diazonium chloride compound and a hydroxyl group-containing compound A diazo resin represented by a condensate of p-diazodiphenylamine and formaldehyde. Specifically, Shoko 4
Examples thereof include those described in JP-A-7-1167 and JP-B-57-43890.

(6) Polyisoprene rubber or polybutadiene rubber cyclized with a bis azide compound, or a photosensitive composition containing cresol novolak resin as a main component. These photosensitive compounds form a hydrophilic swelling layer on a substrate. At this time, it is added by using a method of adding to the composition and allowing it to exist in the layer, or a method of forming a hydrophilic swelling layer and then applying the photosensitive composition onto the layer and impregnating the layer.

In the case of a photosensitive composition using a polymer or an oligomer having a relatively high molecular weight, the former method of simultaneous addition during the formation of the hydrophilic swelling layer is advantageously performed, and a monomer oligomer having a relatively low molecular weight is used. In the case of the photosensitive composition used, the latter impregnation method is advantageous.

Further, a known photosensitizer can be added to the hydrophilic swelling layer of the original plate for the purpose of sensitizing these photosensitive compounds, and a dye or a dye is added to the hydrophilic swelling layer. It is possible to add trace amounts of various additives such as pigments, pH indicators, leuco dyes, surfactants and organic acids. In particular, it is preferable that the image portion or the non-image portion be dyed or faded in the plate making process.

In the present invention, when a primer layer is provided, it is preferably provided between the substrate and the hydrophilic swelling layer, and particularly preferably provided in contact with the hydrophilic swelling layer.

The substrate of the lithographic printing plate used in the present invention is not limited at all, except that it is required to have flexibility that can be attached to an ordinary lithographic printing machine and to withstand the load applied during printing. Typical examples include a metal plate of aluminum, copper, iron, or the like, a plastic film such as a polyester film or a polypropylene film, coated paper, a rubber sheet, and the like. Further, the substrate may be a composite of the above materials.

Next, a plate making method using the lithographic printing plate of the present invention will be described.

The lithographic printing plate of the present invention can be made into a printing plate through a negative working plate making process. That is, the image is exposed through a negative original film by a normal exposure light source.

The lithographic printing plate of the present invention can be made into a printing plate through so-called direct plate making using a laser. That is, image formation is performed by laser beam irradiation.

After such exposure, rinsing with water or a developing solution, if necessary, dissolves and removes or unsensitizes the photosensitive compound present in the hydrophilic swelling layer in the unexposed area. A swellable non-image area is formed, and the photosensitive compound is photocrosslinked and cured in the exposed area.

Next, a printing method using the planographic printing plate of the present invention will be described.

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

After forming an image on the lithographic printing plate of the present invention,
The lithographic printing press is mounted on a plate cylinder, and the plate surface is supplied with ink from an inking roller that contacts the plate cylinder. The non-image area having the hydrophilic swelling layer on the plate swells with the dampening solution supplied from the dampening solution supply device and repels the ink. On the other hand, the image portion receives ink and supplies the ink to the surface of the offset blanket cylinder or the surface of the printing medium to form a printed image.

The fountain solution used for printing the lithographic printing plate of the present invention may be, for example, pure water containing no additive. Can be used. When printing using the lithographic printing plate of the present invention, it is preferable to use pure water having no such additive.

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

[0080]

EXAMPLES The fine particles used in Examples 1 to 10 are as follows.

Titanium oxide (rutile type) (Ishihara Sangyo Co., Ltd.)
“CR-60”, average primary particle size 0.209 μm)
.. Example 1, titanium oxide (rutile type) (“R-58” manufactured by Ishihara Sangyo Co., Ltd.)
0, average primary particle diameter 0.282 μm) Example 2, titanium oxide (anatase type) (“ST” manufactured by Ishihara Sangyo Co., Ltd.)
S-21 ", average primary particle diameter 0.020 μm) Example 3, titanium oxide (anatase type) (" W- "manufactured by Ishihara Sangyo Co., Ltd.)
Example 10, titanium oxide (rutile type) (“R-93” manufactured by Ishihara Sangyo Co., Ltd.)
0, average primary particle diameter 0.255 μm) Example 5, titanium oxide (anatase type) (“FA-80” manufactured by Furukawa Machine Metal Co., Ltd., average primary particle diameter 0.11 μm)
Example 6, zinc oxide (“FINEX-75” manufactured by Sakai Chemical Co., Ltd., average primary particle diameter 0.010 μm) ··· Example 5, acrylic resin (“MP-1000” manufactured by Soken Chemical Co., Ltd.)
(Average primary particle diameter: 0.40 μm)...

These fine particles were used after having been subjected to a hydrophilization treatment by any of the following treatment examples 1 to 3.

(Treatment Example 1) The following hydrophilizing composition was placed in a vibrating mill and vibrated and stirred with steel balls for 3 hours to perform hydrophilizing treatment.

<Hydrophilic composition (parts by weight)> (1) 30 parts by weight of fine particles described in Table 1 (2) 1 part by weight of a wetting and dispersing agent (3) 69 parts by weight of purified water (Example 2 of treatment) The hydrophilizing composition was stirred with a homogenizer at 10,000 revolutions × 5 minutes to perform a hydrophilizing process.

<Hydrophilic composition (parts by weight)> (1) 20 parts by weight of fine particles described in Table 1 (2) 0.5 part by weight of a binder polymer having a wet dispersing effect (3) 79.5 parts by weight of purified water (Treatment example 3) The following hydrophilizing composition was weighed in a flask and reacted at 100 ° C for 8 hours.

<Hydrophilic composition (parts by weight)> (1) Fine particles described in Table 1 10 parts by weight (2) Aluminum hydroxide (reactive cross-linking agent) 2 parts by weight (3) Acetic acid small amount (4) Ethyl cellosolve 41 parts by weight (5) 47 parts by weight of purified water.

(Examples 1 to 6) Example of application of hydrophilic swelling layer (i) Aluminum substrate having a thickness of 0.24 mm (manufactured by Sumitomo Light Metal Co., Ltd.)
After applying the following hydrophilic swelling layer coating solution to the
Heat treatment was performed for 3 minutes, and a hydrophilic swelling layer having a dry weight of 3 g / m ² was applied.

<Composition of hydrophilic swelling layer (parts by weight)> (1) 75 parts by weight of hydrophilic polymer [acrylamide-n-butyl methacrylate copolymer (weight composition ratio 70/30)] (2) Fine particles described in Table 1 15 parts by weight (3) Ethylene glycol diglycidyl ether 10 parts by weight (4) Purified water 900 parts by weight Example of applying hydrophilic swelling layer (R) 0.24 mm thick aluminum substrate (Sumitomo Light Metal Co., Ltd.)
After applying the following hydrophilic swelling layer coating solution,
Heat treatment was performed for 10 minutes, and a hydrophilic swelling layer having a dry weight of 2.4 g / m ² was applied.

(1) Hydrophilic polymer [vinyl acetate-methyl acrylate copolymer (weight composition ratio 50/50) saponified product] 32 parts by weight (2) Aqueous latex “JSR0596” [carboxy-modified styrene-butadiene copolymer latex : Japan Synthetic Rubber Co., Ltd.] 32 parts by weight (3) 30 parts by weight of fine particles described in Table 1 (4) 6 parts by weight of 2-aminopropyltrimethoxysilane (5) 900 parts by weight of purified water On the hydrophilic swelling layer Apply the following photosensitive layer composition,
Thereafter, heat treatment was performed at 100 ° C. for 2 minutes to apply and impregnate a 1.2 g / m ² photosensitive composition to obtain a lithographic printing plate precursor.

<Photosensitive composition (parts by weight)> (1) 20 parts by weight of a salt of paradiphenylamine condensed with paraformaldehyde (2) 70 parts by weight of polyvinyl alcohol GL-05 (manufactured by Nippon Synthetic Chemical Co., Ltd.) (3) 2) parts by weight of Vectria Pure Blue BOH (manufactured by Hodogaya Chemical Co., Ltd.) (4) 898 parts by weight of methylcellosolve Use, PC
W (PLATE CONTOROL WEDGE: manufactured by KALLE Co., Ltd.) for 90 seconds through a negative film (3.6 mW / c
m ² ). Next, the entire surface of the plate was rinsed with tap water, and the unexposed portion of the photosensitive layer composition was washed to obtain a printing plate.

The obtained printing plate was mounted on a sheet-fed offset printing machine “Sprint 25: manufactured by Komori Corporation”, and then supplied with high-quality paper (62.5 kg / Kiku ).

As evaluation methods, evaluation was made of ink repellency, allowable range of fountain solution, ink adhesion and rub resistance.

The ink repellency was evaluated under more severe conditions than in normal printing. That is, printing is performed using an ink obtained by adding 30 parts by weight of an ink solvent (manufactured by Mitsubishi Chemical Corporation: "Dialen 168") to 100 parts by weight of a commercially available oil-based ink (TRANS-G, black ink: Dainippon Ink and Chemicals, Inc.). Was performed, and it was examined whether or not background soiling occurred with a standard dampening solution amount (5 scales). The case where a printed matter without background stain was obtained was evaluated as ○, and the case where background stain was observed was evaluated as x.

The evaluation of the allowable range of the dampening solution was carried out by printing with a commercially available ink (TRANS-G, black ink: Dainippon Ink and Chemicals, Inc.). The case where good printed matter without loss was obtained was evaluated as ○, and the case where soiling or water loss was observed was evaluated as ×. It was determined that printing with a wider range of dampening solution volume (scale) indicates a wider dampening solution tolerance.

As the evaluation of the ink inking property, the fountain solution 7.
At 5 scales, the case where the reflection density of the solid portion exceeded 1.7 was rated as ○, the case where the reflection density was 1.5 to 1.7 was Δ, and the case where the reflection density was less than 1.5 was rated X.

The evaluation of rub resistance was carried out by the following method. The plate surface after the test is visually observed. When the plate surface has no scratches, ○ indicates a slight scratch on the plate surface (a usable level for printing a small number of copies (light printing)), and the plate does not peel. The case where it can be seen was evaluated as x.

<Scratch test> Three pieces of Heize gauze cut to 6 × 6 cm were stacked, a 5 × 5 × 2.5 cm rectangular parallelepiped (made of iron, about 500 g) was placed thereon, and a printing plate moistened with water was reciprocated 3000 times. Rubbed.

Comparative Example 1 A lithographic printing plate was prepared in the same manner as in Example 1 except that no titanium oxide was used. The composition of the hydrophilic swelling layer was in accordance with the application example (i) of the hydrophilic swelling layer.

Comparative Example 2 A lithographic printing plate was prepared in the same manner as in Example 2 except that the hydrophilic treatment of titanium oxide was not performed.

The evaluation results are shown in Table 1.

[0101]

[Table 1] (Note 1) Crystal structure of titanium oxide: rutile type (R type),
The anatase form was designated as (A form).

(Note 2) In Example 5, two kinds of fine particles were used in combination and added to the hydrophilic swelling layer. The amount of addition was such that titanium oxide and zinc oxide were used in a ratio of 10: 2, and the total was the same as in Example 1.

(Note 3) <Wet dispersant> a: Sodium dialkyl sulfosuccinate b: Fluorosurfactant c: Formalin condensate of sodium naphthalene sulfonate <Evaluation method> Ink repellency : Commercial ink (ink) 100 Printing is carried out with an ink obtained by adding 10 parts by weight of a waist-cutting agent to parts by weight.-When a printed matter free of background stain is obtained (O)-When background stain is generated (X) Allowable damping water width : Printing with a commercially available ink, and in each fountain solution (scale):-A good printed product without ground stains and water loss was obtained (O)-When soiling or water loss was observed (X) The fact that printing is possible with a wider range of dampening water amount (scale) indicates that the dampening water tolerance is wider.

Ink inking property : At 7.5 scales of fountain solution, when the reflection density of the solid portion exceeds 1.5 (○), when it is 1.3 to 1.5 (△), and 1. When less than 3 (x): Abrasion resistance test : ・ No scratch on plate (○) ・ Slight scratch on plate ( useful level for small number of copies (light print)) (△) When peeling is observed on the plate surface (x) (Examples 7 to 10) A lithographic printing plate was obtained and printed in the same manner as in Example 1 except that the following hydrophilic swelling layer composition was used in Example 1. An evaluation was performed. The amounts of the hydrophilic polymer and titanium oxide added are as described in Table 2.

Example of coating of hydrophilic swelling layer (a) Aluminum substrate 0.24 mm thick (Sumitomo Light Metal Co., Ltd.)
After applying the following hydrophilic swelling layer coating solution to 140 ° C
Heat treatment was performed for 30 minutes, and a hydrophilic swelling layer having a thickness of 2.0 g / m ² by dry weight was applied.

<Composition of hydrophilic swelling layer (parts by weight)> (1) Hydrophilic polymer [acrylamide-n-butyl methacrylate copolymer (weight composition ratio 70/30)] (2) Fine particles of Example 1 (3) Ethylene glycol diglycidyl ether 10 parts by weight (4) Purified water 900 parts by weight Table 2 summarizes the evaluation results.

[0107]

[Table 2] It can be seen that the introduction of hydrophilically treated titanium oxide into the hydrophilic swelling layer improves the ink resilience, allows a wider fountain solution tolerance, and provides a lithographic printing plate with more excellent ink adhesion. Further, since the abrasion resistance is improved, the printing durability is also expected to be improved.

[0108]

According to the present invention, there is provided a novel ink which has high ink repellency without desensitizing treatment, has a wide allowable range of dampening solution, and is free of dampening solution isopropanol (IPA). A lithographic printing plate having excellent ink repellency and high printing durability can be obtained.

Claims (3)

[Claims] 1. A planographic printing plate having at least a hydrophilic swelling layer on a substrate, wherein the hydrophilic swelling layer contains titanium oxide whose surface has been hydrophilized. 2. The titanium oxide has an average primary particle size of 0.1.
The lithographic printing plate according to claim 1, wherein the thickness is from 005 to 5 µm. 3. The lithographic printing plate according to claim 1, wherein the content of the titanium oxide is 5 to 60 parts by weight based on 100 parts by weight of the solid content of the hydrophilic swelling layer.