JPH05232749A - Electrophotographic plate for planographic printing - Google Patents

Abstract

PURPOSE:To provide an electrophotographic plate for planographic printing with easy-to-perform printing works, with which printing of high picture quality excellent in the printing adaptability are obtained. CONSTITUTION:A printing plate includes a photoconductive layer on one side of a support and an under-layer immediately under the photoconductive layer being embodied in a complex layer structure in which the under-layer has an outermost layer with a surface specific resistivity below 1X10<11>OMEGA and an inner layer whose Young's modulus is below 1000kg/cm<2>, with which the electrophotographic characteristics (in particular, prevention of fog) and the resistance against printing burden (in particular, suppression of plate severance) can be obtained compatibly.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic lithographic printing plate precursor, and more particularly to an electrophotographic lithographic printing plate precursor having excellent printability, capable of obtaining a printed matter of high image quality and having good printing workability. is there.

[0002]

2. Description of the Related Art Conventionally, as a method for producing a lithographic printing plate by an electrophotographic method, a photoconductive layer of an electrophotographic lithographic printing plate precursor is uniformly charged and imagewise exposed, and then dry development or a liquid toner is carried out by a dry toner. A method is generally adopted in which a toner image is obtained by wet-developing with, then the toner image is fixed, and then treated with a desensitizing liquid (etching liquid) to make the non-image portion having no toner image hydrophilic. There is. The printing plate thus prepared is attached to a plate cylinder of a printing machine for lithographic printing. At this time, dampening water is used during printing. Paper or the like having conductivity has been conventionally used as a support of an electrophotographic lithographic printing plate precursor, but the permeation of water into this support affected printing durability and image quality performance. That is, when the above-mentioned etching liquid or immersion water during printing enters the support, problems such as elongation of the printing plate and plate breakage occur. Therefore, such an electrophotographic lithographic printing plate precursor has properties as a general electrophotographic photosensitive material, that is, the surface has uniform electric characteristics and is excellent in image forming performance and developability, and there is no fog or printing unevenness. With electrophotographic characteristics such as having environmental stability, printing characteristics when used as a printing plate, that is, water resistance to desensitizing treatment and fountain solution,
Compatibility with organic solvent resistance, printing workability, environmental stability, etc. is desired. For this purpose, for example, one or both surfaces of the support may be coated with a water-resistant epoxy resin or a copolymer of ethylene and acrylic acid or the like (Japanese Patent Laid-Open No. 50-13890).
4, No. 55-105580, No. 59-68753, etc.), or providing a laminate layer of polyethylene or the like (Japanese Patent Laid-Open No. 58-57994). Further, a method of providing a backing layer (back layer) on the surface of the support opposite to the surface having a photoconductive layer (also referred to as a top layer) to impart water resistance and retain various functions, and further a photoconductive layer A method for providing an electrophotographic property and water resistance by providing an intermediate layer between the precoat layer and the precoat layer (Japanese Patent Laid-Open No. 2-5046).
No. 5) is being conducted.

[0003]

However, when an under layer (undercoat layer) is provided directly under the photoconductive layer, the electrophotographically uniform characteristics can be stably maintained as compared with the conventional single photoconductive layer. However, it is difficult to achieve both water resistance and strength retention.
That is, if an underlayer is provided and it is attempted to maintain uniform electrophotographic properties, the support becomes hard and brittle due to the nature of the material used, and it may break, break, or jump out of the plate cylinder. There was a problem. Further, if a tough and supple material is used for the under layer, electrophotographically uniform stability cannot be obtained, resulting in increased fog during development and shark-skin-like unevenness. The present invention has been made to solve the above-mentioned problems caused by providing an underlayer between a support and a photoconductive layer and directly under the photoconductive layer in an electrophotographic lithographic printing plate precursor.

[0004]

[Means for Solving the Problems]

The present invention is an electrophotographic lithographic printing plate precursor comprising at least a photoconductive layer on one surface of a support and an underlayer provided directly below the photoconductive layer, and a plurality of the underlayers. The plurality of layers have a surface resistivity of 1 ×
Outermost layer with 10 ¹¹ Ω or less and Young's modulus of 1000 kg /
The above problem is solved by an electrophotographic lithographic printing plate precursor having an inner layer of not more than cm ² .

[0006]

The feature of the present invention is that the structure of the under layer provided between the support and the photoconductive layer and directly below the photoconductive layer in contact with the photoconductive layer is a multi-layered structure, and the electrophotographic characteristics (fog) ) And strength retention. That is, the under layer of the present invention comprises an outermost layer having a surface resistivity of 1 × 10 ¹¹ Ω or less (a layer immediately below the photoconductive layer in contact with the photoconductive layer) and a Young's modulus of 1
It has an inner layer (layer on the support side) of 000 kg / cm ² or less.

In the present invention, since the outermost layer of the under layer has a surface resistivity of 1 × 10 ¹¹ Ω or less, the uniformity of the electrophotographic characteristics of the photoconductive layer provided thereon is not disturbed. The image forming performance and the developing performance are the same as those of the single photoconductive layer. Further, the Young's modulus of the inner layer is 1000 kg / cm ² or less, and by providing the layer having the rigidity in this region, plate breakage does not occur. In the present invention, by adopting a multi-layer structure in which the functions are shared in this way, the flexibility of the support is lost when the surface resistivity of the conventional single layer is reduced, and the plate is not cracked during printing. I was able to solve the problem of causing it to wake up.

The underlayer of the present invention will be described in more detail below. The outermost layer of the under layer of the present invention is a layer having a surface resistivity of 1 × 10 ¹¹ Ω or less. Surface resistivity is 1 × 10
^If it exceeds ¹¹ Ω, fog becomes large, which is not preferable. Regarding this point, detailed experimental results are shown in Examples 1 and 2 described later. The lower limit of the surface resistivity is 1 × 10 ⁷ Ω. If the surface resistivity is smaller than this, a leak occurs in the peripheral portion of the entire original plate after charging, and an image cannot be obtained even after exposure and development, which is not preferable. In order to bring the surface resistivity of the outermost layer of the present invention into the above range, the outermost layer includes, for example, titanium oxide, tin oxide, indium oxide, metal oxides such as zinc oxide, colloidal alumina, colloidal silica,
Conductive substances such as carbon black, polyoxyethylene alkyl ether, fatty acids, fatty acid monoglycerides, alkyl sulfonates, alkyl methyl ammonium salts, and surfactants such as alkyl phosphate alkanolamine salts and polyoxyethylene alkyl phosphates. Include. These substances may be added at the time of preparing and dispersing the outermost layer composition, or the sample may be impregnated with the conductive substance dispersion liquid after coating the outermost layer.

The outermost layer of the under layer of the present invention comprises the above-mentioned conductive material and another outermost layer forming material, and examples of the forming material include various water resistant materials, water resistant organic solvent resistant materials, and synthetic materials. It is possible to use one or more types of emulsions, and also natural or synthetic hydrophilic polymers. The water-resistant material is a water-resistant film-forming material such as polyvinyl chloride, acrylic resin, polystyrene, polyethylene, alkyd resin, styrene-butadiene copolymer, ethylene-vinyl acetate copolymer, or organic solvent resistant film. Forming materials such as starch, oxidized starch, PVA, methyl cellulose,
Examples thereof include hydroxyethyl cellulose and CMC.
Examples of the water resistant organic solvent resistant material include ethylene-
A vinyl alcohol copolymer, a high degree of polymerization polyester, a high degree of polymerization polyurethane or the like is used. Also, starch, PV
A, an acrylic resin (however, a reactive acrylic resin, which may be an organic solvent solution type or an O / W type emulsion type), an alkyd resin (however, an air-curable type), and a cross-linking agent such as a melamine resin are used in combination. It can also be used as a water resistant organic solvent resistant material. As the synthetic emulsion,
Acrylic ester, methacrylic acid ester, vinyl chloride, vinylidene chloride, vinyl acetate, polyurethane, prepolymer, acrylonitrile, butadiene, obtained by emulsion polymerization or emulsion copolymerization of monomers or prepolymers such as styrene-butadiene Can be mentioned. As natural or synthetic hydrophilic polymers, in addition to ordinary lime-processed gelatin, acid-processed gelatin, modified gelatin, gelatin such as derivative gelatin, albumin, sodium alginate, gum arabic, latex, cellulose, hydroxyethyl cellulose, carboxymethyl cellulose. And water-soluble derivatives such as starch, polyvinyl alcohol, polyvinylpyrrolidone, polyacrylamide, and hydrophilic polymers such as styrene-maleic anhydride copolymer. These outermost layer forming materials can be used together. A dispersant, a leveling agent, a cross-linking agent, etc. can be added to the outermost layer, if necessary. The presence ratio of the conductive material in the total amount of the composition for forming the outermost layer varies depending on the material used, but it suffices if the surface resistivity satisfies 1 × 10 ¹¹ Ω or less, usually about 0.1 to 10% by weight. Is.

The inner layer of the present invention may be one which satisfies the condition that the Young's modulus of the inner layer composition as a single film is 1000 kg / cm ² or less. Young's modulus 10
When it exceeds 100 kg / cm ² , the toughness of the plate is impaired and becomes brittle, and as the support absorbs water during printing and stretches, the inner layer is cracked and eventually the plate is cut.
In this regard, experimental results will be described in detail in Examples 1 and 2 described later.

As the inner layer forming material, various water resistant materials, water resistant organic solvent resistant materials and synthetic emulsions described above as the outermost layer forming material can be used, and further a water-soluble polymer compound can also be used. Examples of the water-soluble polymer compound include starch or a water-soluble derivative thereof, a water-soluble cellulose derivative, casein, polyvinyl alcohol, a styrene maleic anhydride copolymer, and a vinyl acetate-maleic anhydride copolymer. .. Also in this case, the amount used is selected so that the water absorption of the inner layer is 15 g / m ² or less. These materials for forming the inner layer can be used in combination, and a dispersant, a leveling agent, a cross-linking agent and the like can be added if necessary, as in the case of the outermost layer. Further, by adding a hydrophilic polymer binder such as an organic titanium compound to one or both of the outermost layer and the inner layer, the adhesion between both layers can be improved.

In the present invention, the thickness of the outermost layer is not particularly limited as long as it can exert its performance, but is about 1 to 25 μm, preferably about 1 to 15 μm. The inner layer has a thickness of 1 to 30 μm, preferably 3
Is about 20 μm. When the inner layer has a multilayer structure, the total thickness may be within this range. The total thickness of the entire under layer including the outermost layer and the inner layer of the present invention is generally 1 to 60 μm, preferably 4 to 40 μm.

As the support of the present invention, any of the known supports used for this type of electrophotographic lithographic printing plate precursor can be used. For example, a substrate such as metal, paper, or a plastic sheet, or a substrate which is electrically conductive by impregnating a low resistance substance, or a substrate having a water-resistant adhesive layer or at least one precoat layer on the surface thereof. It is possible to use, for example, a substrate obtained by laminating a base conductive plastic having vapor deposited Al, Al or the like on paper. Further, a back layer may be provided on the back surface of the support (the surface opposite to the surface on which the photoconductive layer is provided) by a known means. Specifically, as an example of the conductive substrate or conductive material, Yukio Sakamoto "Electrophotography"
14, (No.1), p2-11 (1975), Hiroyuki Moriga "Introduction to Special Paper Chemistry" Polymer Publishing (1975), M.
F. Hoover, J. Macromol. Sci. Chem., A-4
(6), p1327 to 1417 (1970) and the like are used.

The photoconductive layer of the present invention contains at least a photoconductor and a binder, and the photoconductor may be either an inorganic material or an organic material. Examples of the inorganic photoconductive material include Si, Ge, zinc oxide, cadmium sulfide, titanium oxide, selenium, cadmium selenide, zinc selenide or lead oxide, Se—Te alloy, As ₂ S ₃ , As.
Examples include chalcogen alloys such as ₂ Se ₃ . Examples of the organic photoconductive material include photoconductive cyanine pigments, photoconductive quinoline pigments, photoconductive phthalocyanine pigments, photoconductive pyrylium salt pigments, substituted vinyl oxazoles, triphenylamine derivatives, anthracenes, and benzocondensates. Heterocycles, pyrazoline or imidazole derivatives, oxadiazole derivatives, vinyl aromatic polymers and their copolymerization products, fluorenone derivatives,
Polyarylalkanes such as triarylmethane leuco dyes and squaric acid derivative dyes, perylene, tetracene, carbazole, tetrabenzyl-p-phenylenediamine, squarylium, indigo, dimethylperimide, polyzenyltetracene, polyzenylperylene Examples thereof include acylhydrazone derivatives, benzthiazole derivatives, tetracyanopyrene, chlorocyan blue and the like. You may use these together. As the binder, use a material known as a binder for silicone resin, polystyrene, polyacrylic acid or polymethacrylic acid ester, polyvinyl acetate, polyvinyl chloride, polyvinyl butyral and their derivatives and other photoconductive layers. You can The amount of the photoconductor in the photoconductive layer is such that the weight ratio of the photoconductive substance to the binder is, for example, in the range of 3: 1 to 20: 1, but is not particularly limited in the present invention. .. Further, if necessary, a sensitizer and a coating aid and other additives used when coating can be added. The thickness of this photoconductive layer is usually about 5 to 30 μm, but is not particularly limited in the present invention. Further, in order to improve the adhesive force between the photoconductive layer and the under layer, the surface of the under layer is previously formed, for example, in US Pat.
As described in Japanese Patent No. 1,908, it is preferable to perform surface treatment such as corona discharge treatment, glow discharge treatment, flame treatment, ultraviolet treatment, ozone treatment, and plasma treatment.

The lithographic printing plate precursor according to the present invention may be produced by a technique known in the field of manufacturing electrophotographic lithographic printing plate precursors of this type, and examples of dispersion methods include a ball mill, a colloid mill, an ultrasonic disperser, and 3 This roll mill, grain mill,
A normal one such as a homogenizer or a homomixer can be used. As a coating method, an air knife coater,
A trailing grade coater, wire bar coater, reverse roll coater, kiss roll coater, fountain coater, etc. can be used.

The above-mentioned original plate of the present invention is made into a lithographic printing plate after undergoing usual processes such as charging, image exposure and development. Also,
In addition to the usual wet development, for example, Japanese Patent Application No. 63-89373.
It is also suitable for the development of a direct power supply system as described in Japanese Patent Publication No. Hei 2-132464.

[0017]

The present invention will be described below with reference to examples, but the present invention is not limited thereto. Example 1 A dispersion of SBR emulsion, poval (polyvinyl alcohol), clay, melamine, and water was applied to one surface of a high-quality paper having a basis weight of 100 g / m ² by using a wire bar, and the same was placed in an oven at 140 ° C. for 1 minute. 7g after dried
An inner layer of the under layer of / m ² was provided. The amount ratio of the inner layer composition at this time is as follows. With regard to the SBR emulsion and Poval, the Young's modulus when the amount is used as the single film of the eye is from about 300 kg / cm ² to about 3000 k.
Adjust to change in 4 steps in the range of g / cm ² and 4
The types of samples (A), (I), (U), and (E) were obtained. Inner layer composition : SBR emulsion Appropriate amount Poval Appropriate amount Starch 3 parts by weight Clay 30 parts by weight Melamine 3 parts by weight Water 100 parts by weight

The single film of the inner layer composition was prepared by applying the dispersion liquid of the composition to a glass support with a wire bar, air-drying it, and then drying it in an oven at 140 ° C. for 1 minute to give an adhesion amount of 100 g / It is obtained by forming a m ² film and peeling it from the glass support.

Next, the outermost layer composition dispersion comprising a styrene-butadiene resin (hereinafter abbreviated as SBR) emulsion, clay, conductive titanium oxide, melamine, and water was applied on the inner layer using a wire bar, It was dried in an oven at 140 ° C. for 1 minute to provide an outer layer having a deposition amount of 3 g / m ² . The amount ratio of the outermost layer composition at this time is as follows,
The amount of conductive titanium oxide is 4 when the surface resistivity ρs of the outer layer is in the range of about 1 × 10 ⁹ Ω to about 1 × 10 ¹² Ω.
Adjust so that it changes in stages, and
It was applied to each of (e), and four kinds of samples were prepared, for a total of 16 kinds of samples. Outer layer composition: SBR emulsion 23 parts by weight Clay 30 parts by weight Conductive titanium oxide Appropriate amount Melamine 2 parts by weight Water 100 parts by weight

On the back side of the paper which is the support of the above 16 kinds of samples, 25 parts by weight of SBR emulsion, 45 parts by weight of clay, 4 parts by weight of casein, 4 parts by weight of melamine and 1 part of water.
A dispersion liquid consisting of 100 parts by weight is applied using a wire bar, dried in an oven at 140 ° C. for 1 minute, and the adhesion amount is 10
A back layer of g / m ² was provided. The results of measuring the Young's modulus and the surface resistivity of the outermost layer of the single film of the inner layer composition of the 16 kinds of samples thus obtained are summarized in Table 1.

[Table 1]

On the outer layer side of each sample (support) obtained above, 100 parts by weight of photoconductive zinc oxide, acrylic resin 20
3. 4 parts by weight, toluene 125 parts by weight, phthalic anhydride 0.1 part by weight, and rose bengal 4% methanol solution 4.
The dispersion liquid consisting of 5 parts by weight is applied using a wire bar, dried in an oven at 110 ° C. for 20 seconds, and the applied amount is 2
An electrophotographic photosensitive paper was prepared by providing a photoconductive layer of 5 g / m 2.
About this electrophotographic photosensitive paper Commercial electrophotographic plate making machine EL
The product developed with P404V (manufactured by Fuji Photo Film Co., Ltd.) was developed at 20 ° C., 65% RH and 15 ° C., 30%.
When the fog in the non-image area was examined under the environmental conditions of RH,
The results shown in Tables 2 and 3 were obtained. In addition, Table 2 and Table 3
Each symbol in means the evaluation of fog density as follows. ○: Fog density 0.6 or less △: 0.7 to 1.0 ▲: 1.0 to 1.4 ×: 1.5 or more When the fog density is higher than 0.7, stains occur during printing. Therefore, it is not suitable for practical use.

[0022]

[Table 2]

[0023]

[Table 3]

From the results shown in Tables 2 and 3, even under the more severe environmental conditions of 15 ° C. and 30% RH, the surface resistivity of the under layer can be controlled within the range of the present invention to obtain sufficient electron emission. It was confirmed that an area that satisfies photographic performance could be secured.

Next, the above (a-1 to 4) to (e-1 to
Commercially available yellow blood salt based etchant ELP-E
2 (Fuji Photo Film Co., Ltd.) is used for etching to form a printing plate, which is then applied to an AD-80 type printing machine (Ryobi Printing Co., Ltd.) to show the performance as a printing plate after printing 200 sheets. Table 4 shows the results of examining the plate out of print.

[0026]

[Table 4] In addition, each symbol of Table 4 shows the following evaluation results. ◯: No print cut, no cracks at all △: Print cut, cracks at least 1/3 of the whole ▲: Print cut, cracks at least 1/2 of the whole ×: Print break, completely cut It is not suitable for practical use if there is a print out.

The combined results of Tables 3 and 4 above are
As shown in Table 5, among the 16 types of samples, the samples with less fog and plate breakage are U-1, U-2, E-1, E-
2, that is, the surface resistance of the outer layer is 1 × 10 ¹¹ Ω or less and the Young's modulus of the inner layer is 10 which is limited to the present invention.
It is clearly understood that the range of 00 kg / cm ² or less is the range where the object of the present invention can be achieved.

[Table 5]

Example 2 In Example 1, an acrylic emulsion was used in place of the SBR emulsion used for the inner layer and the outer layer of the under layer, and the amount of poval was changed from the Young's modulus of the inner layer of about 400 kg / cm ^2. About 2000 kg / cm ²
The same procedure as in Example 1 was carried out except that the adjustment was made so as to be changed in three steps within the range. Inner layer composition: Acrylic emulsion 30 parts by weight PVA appropriate amount of starch and 3 parts by weight Clay 30 parts by weight of melamine 3 parts by weight of water 100 parts by weight outer layer composition: acrylic emulsion 23 parts by weight Clay 30 parts by weight conductive titanium oxide qs melamine 2 parts by weight of water 100 parts The results obtained by measuring the Young's modulus of the single film of the inner layer composition of the obtained 12 kinds of samples and the surface resistivity of the outer layer are shown in Table 6.
Are summarized in.

[Table 6]

When these samples were subjected to development (evaluation of fog) and printing test in the same manner as in Example 1, Table 7
The results shown in are obtained. Each symbol in Table 7 has the same meaning as in Tables 2 to 5.

[0030]

[Table 7] Of the 12 types of samples, the one with less fog and plate out,
KA-5, KA-6, KI-5, KI-6, that is, the surface resistance of the outer layer is 1 × 10 ¹¹ Ω or less and the Young's modulus of the inner layer is 1000 kg / cm ² or less, which is limited to the present invention. It is clearly understood that the range of is a region where the object of the present invention can be achieved.

Comparative Example 1 A dispersion of SBR emulsion, poval, starch, clay, melamine, and water was applied to one side of a high-quality paper having a basis weight of 100 g / m ² by using a wire bar, and then was placed in an oven at 140 ° C. for 1 hour. After drying for one minute, an undercoat layer having an adhesion amount of 15 g / m ² was provided. The amount ratio of the undercoat layer composition at this time is as follows. For the conductive titanium oxide, the amount ratio was adjusted so that the surface resistivity ρs of the undercoat layer was constant at 1 × 10 ⁹ Ω. , SBR emulsion and Poval have a Young's modulus of about 30 when they are used as a single film of the composition.
Attempts were made to adjust it so that it varied from 0 kg / cm ² to about 3000 kg / cm ² . However, the surface resistivity is 1
Young's modulus of 1000 kg / cm while keeping at × 10 ^9.
It could not be less than ² . Undercoat composition: SBR emulsion 30 parts by weight Poval proper amount starch 3 parts by weight clay 30 parts by weight melamine 3 parts by weight water 100 parts by weight SBR emulsion 25 parts by weight and clay 45 parts by weight on the back side of the paper which is the support for these samples. A coating solution containing 4 parts by weight of casein, 4 parts by weight of melamine, 4 parts by weight of melamine and 100 parts by weight of water is applied using a wire bar and dried in an oven at 140 ° C. for 1 minute to deposit a back layer having an adhesion amount of 10 g / m ² . Was established. Furthermore, 100 parts by weight of photoconductive zinc oxide, 20 parts by weight of acrylic resin, 125 parts by weight of toluene, 0.1 part by weight of phthalic anhydride, and 4% methanol solution of rose bengal on the undercoat layer. 5 parts by weight of the dispersion liquid was applied using a wire bar, and a photoconductive layer having an application amount of 25 g / m ² was provided in the oven at 110 ° C. for 20 seconds to prepare an electrophotographic photosensitive paper. A printing test was carried out on each of the obtained electrophotographic photosensitive papers in the same manner as in Example 1. However, no printing plate was found after printing 200 sheets.

[0032]

As described above, according to the present invention, the under layer has a multi-layer structure and the outermost layer has a surface resistivity of 1 ×.
The electrophotographic property, particularly the developing property, is secured at 10 ¹¹ Ω or less, and the Young's modulus of the inner layer is set to 1000 kg / cm ² or less to prevent plate breakage during printing and to achieve both electrophotographic property and printing property. It can be used as a lithographic printing plate precursor.

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[Procedure amendment]

[Submission date] March 13, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Full text

[Correction method] Change

[Correction content]

[Document name] Statement

[Title of Invention] Electrophotographic lithographic printing plate precursor

[Claims]

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic lithographic printing plate precursor, and more particularly to an electrophotographic lithographic printing plate precursor having excellent printability, capable of obtaining a printed matter of high image quality and having good printing workability. is there.

[0002]

2. Description of the Related Art Conventionally, as a method for producing a lithographic printing plate by an electrophotographic method, a photoconductive layer of an electrophotographic lithographic printing plate precursor is uniformly charged and imagewise exposed, and then dry development or a liquid toner is carried out by a dry toner. A method is generally adopted in which a toner image is obtained by wet-developing with, then the toner image is fixed, and then treated with a desensitizing liquid (etching liquid) to make the non-image portion having no toner image hydrophilic. There is. The printing plate thus prepared is attached to a plate cylinder of a printing machine for lithographic printing. At this time, dampening water is used during printing. Paper or the like having conductivity has been conventionally used as a support of an electrophotographic lithographic printing plate precursor, but the permeation of water into this support affected printing durability and image quality performance. That is, when the above-mentioned etching liquid or immersion water during printing enters the support, problems such as elongation of the printing plate and plate breakage occur. Therefore, such an electrophotographic lithographic printing plate precursor has properties as a general electrophotographic photosensitive material, that is, the surface has uniform electric characteristics and is excellent in image forming performance and developability, and there is no fog or printing unevenness. With electrophotographic characteristics such as having environmental stability, printing characteristics when used as a printing plate, that is, water resistance to desensitizing treatment and fountain solution,
Compatibility with organic solvent resistance, printing workability, environmental stability, etc. is desired. For this purpose, for example, one or both surfaces of the support may be coated with a water-resistant epoxy resin or a copolymer of ethylene and acrylic acid or the like (Japanese Patent Laid-Open No. 50-13890).
4, No. 55-105580, No. 59-68753, etc.), or providing a laminate layer of polyethylene or the like (Japanese Patent Laid-Open No. 58-57994). Further, a method of providing a backing layer (back layer) on the surface of the support opposite to the surface having a photoconductive layer (also referred to as a top layer) to impart water resistance and retain various functions, and further a photoconductive layer A method for providing an electrophotographic property and water resistance by providing an intermediate layer between the precoat layer and the precoat layer (Japanese Patent Laid-Open No. 2-5046).
No. 5) is being conducted.

[0003]

However, when an under layer (undercoat layer) is provided directly under the photoconductive layer, the electrophotographically uniform characteristics can be stably maintained as compared with the conventional single photoconductive layer. However, it is difficult to achieve both water resistance and strength retention.
That is, if an underlayer is provided and it is attempted to maintain uniform electrophotographic properties, the support becomes hard and brittle due to the nature of the material used, and it may break, break, or jump out of the plate cylinder. There was a problem. Further, if a tough and supple material is used for the under layer, electrophotographically uniform stability cannot be obtained, resulting in increased fog during development and shark-skin-like unevenness. The present invention has been made to solve the above-mentioned problems caused by providing an underlayer between a support and a photoconductive layer and directly under the photoconductive layer in an electrophotographic lithographic printing plate precursor.

[0004]

[Means for Solving the Problems]

The present invention is an electrophotographic lithographic printing plate precursor comprising at least a photoconductive layer on one surface of a support and an underlayer provided directly below the photoconductive layer, and a plurality of the underlayers. The plurality of layers have a surface resistivity of 1 ×
Outermost layer with 10 ¹¹ Ω or less and Young's modulus of 1000 kg /
The above problem is solved by an electrophotographic lithographic printing plate precursor having an inner layer of not more than cm ² .

[0006]

The feature of the present invention is that the structure of the under layer provided between the support and the photoconductive layer and directly below the photoconductive layer in contact with the photoconductive layer is a multi-layered structure, and the electrophotographic characteristics (fog) ) And strength retention. That is, the under layer of the present invention comprises an outermost layer having a surface resistivity of 1 × 10 ¹¹ Ω or less (a layer immediately below the photoconductive layer in contact with the photoconductive layer) and a Young's modulus of 1
It has an inner layer (layer on the support side) of 000 kg / cm ² or less.

In the present invention, since the outermost layer of the under layer has a surface resistivity of 1 × 10 ¹¹ Ω or less, the uniformity of the electrophotographic characteristics of the photoconductive layer provided thereon is not disturbed. The image forming performance and the developing performance are the same as those of the single photoconductive layer. Further, the Young's modulus of the inner layer is 1000 kg / cm ² or less, and by providing the layer having the rigidity in this region, plate breakage does not occur. In the present invention, by adopting a multi-layer structure in which the functions are shared in this way, the flexibility of the support is lost when the surface resistivity of the conventional single layer is reduced, and the plate is not cracked during printing. I was able to solve the problem of causing it to wake up.

The underlayer of the present invention will be described in more detail below. The outermost layer of the under layer of the present invention is a layer having a surface resistivity of 1 × 10 ¹¹ Ω or less. Surface resistivity is 1 × 10
^If it exceeds ¹¹ Ω, fog becomes large, which is not preferable. Regarding this point, detailed experimental results are shown in Examples 1 and 2 described later. The lower limit of the surface resistivity is 1 × 10 ⁷ Ω. If the surface resistivity is smaller than this, a leak occurs in the peripheral portion of the entire original plate after charging, and an image cannot be obtained even after exposure and development, which is not preferable. In order to keep the surface resistivity of the outermost layer of the present invention within the above range, the outermost layer may be formed of, for example, titanium oxide, tin oxide, indium oxide or zinc oxide.
Conductive metal oxide, colloidal alumina, colloidal silica, carbon black, polyoxyethylene alkyl ether, fatty acid, fatty acid monoglyceride, alkyl sulfonate, alkyl methyl ammonium salt, and alkyl phosphate alkanolamine salt, polyoxyethylene alkyl A conductive substance such as a surfactant such as phosphate is included. These substances may be added at the time of preparing and dispersing the outermost layer composition, or the sample may be impregnated with the conductive substance dispersion liquid after coating the outermost layer.

The outermost layer of the under layer of the present invention comprises the above-mentioned conductive material and another outermost layer forming material, and examples of the forming material include various water resistant materials, water resistant organic solvent resistant materials, and synthetic materials. It is possible to use one or more types of emulsions, and also natural or synthetic hydrophilic polymers. The water-resistant material is a water-resistant film-forming material such as polyvinyl chloride, acrylic resin, polystyrene, polyethylene, alkyd resin, styrene-butadiene copolymer, ethylene-vinyl acetate copolymer, or organic solvent resistant film. Forming materials such as starch, oxidized starch, PVA, methyl cellulose,
Examples thereof include hydroxyethyl cellulose and CMC.
Examples of the water resistant organic solvent resistant material include ethylene-
A vinyl alcohol copolymer, a high degree of polymerization polyester, a high degree of polymerization polyurethane or the like is used. Also, starch, PV
A, an acrylic resin (however, a reactive acrylic resin, which may be an organic solvent solution type or an O / W type emulsion type), an alkyd resin (however, an air-curable type), and a cross-linking agent such as a melamine resin are used in combination. It can also be used as a water resistant organic solvent resistant material. As the synthetic emulsion,
Acrylic ester, methacrylic acid ester, vinyl chloride, vinylidene chloride, vinyl acetate, polyurethane, prepolymer, acrylonitrile, butadiene, obtained by emulsion polymerization or emulsion copolymerization of monomers or prepolymers such as styrene-butadiene Can be mentioned. As natural or synthetic hydrophilic polymers, in addition to ordinary lime-processed gelatin, acid-processed gelatin, modified gelatin, gelatin such as derivative gelatin, albumin, sodium alginate, gum arabic, latex, cellulose, hydroxyethyl cellulose, carboxymethyl cellulose. And water-soluble derivatives such as starch, polyvinyl alcohol, polyvinylpyrrolidone, polyacrylamide, and hydrophilic polymers such as styrene-maleic anhydride copolymer. These outermost layer forming materials can be used together. A dispersant, a leveling agent, a cross-linking agent, etc. can be added to the outermost layer, if necessary. The presence ratio of the conductive material in the total amount of the composition for forming the outermost layer varies depending on the material used, but it suffices if the surface resistivity satisfies 1 × 10 ¹¹ Ω or less, usually about 0.1 to 10% by weight. Is.

The inner layer of the present invention may be one which satisfies the condition that the Young's modulus of the inner layer composition as a single film is 1000 kg / cm ² or less. Young's modulus 10
When it exceeds 100 kg / cm ² , the toughness of the plate is impaired and becomes brittle, and as the support absorbs water during printing and stretches, the inner layer is cracked and eventually the plate is cut.
In this regard, experimental results will be described in detail in Examples 1 and 2 described later.

As the inner layer forming material, various water resistant materials, water resistant organic solvent resistant materials and synthetic emulsions described above as the outermost layer forming material can be used, and further a water-soluble polymer compound can also be used. Examples of the water-soluble polymer compound include starch or a water-soluble derivative thereof, a water-soluble cellulose derivative, casein, polyvinyl alcohol, a styrene maleic anhydride copolymer, and a vinyl acetate-maleic anhydride copolymer. .. Also in this case, the amount used is selected so that the water absorption of the inner layer is 15 g / m ² or less. These materials for forming the inner layer can be used in combination, and a dispersant, a leveling agent, a cross-linking agent and the like can be added if necessary, as in the case of the outermost layer. Further, by adding a hydrophilic polymer binder such as an organic titanium compound to one or both of the outermost layer and the inner layer, the adhesion between both layers can be improved.

In the present invention, the thickness of the outermost layer is not particularly limited as long as it can exert its performance, but is about 1 to 25 μm, preferably about 1 to 15 μm. The inner layer has a thickness of 1 to 30 μm, preferably 3
Is about 20 μm. When the inner layer has a multilayer structure, the total thickness may be within this range. The total thickness of the entire under layer including the outermost layer and the inner layer of the present invention is generally 1 to 60 μm, preferably 4 to 40 μm.

As the support of the present invention, any of the known supports used for this type of electrophotographic lithographic printing plate precursor can be used. For example, a substrate such as metal, paper, or a plastic sheet, or a substrate which is electrically conductive by impregnating a low resistance substance, or a substrate having a water-resistant adhesive layer or at least one precoat layer on the surface thereof. It is possible to use, for example, a substrate obtained by laminating a base conductive plastic having vapor deposited Al, Al or the like on paper. Further, a back layer may be provided on the back surface of the support (the surface opposite to the surface on which the photoconductive layer is provided) by a known means. Specifically, as an example of the conductive substrate or conductive material, Yukio Sakamoto "Electrophotography"
14, (No.1), p2-11 (1975), Hiroyuki Moriga "Introduction to Special Paper Chemistry" Polymer Publishing (1975), M.
F. Hoover, J. Macromol. Sci. Chem., A-4
(6), p1327 to 1417 (1970) and the like are used.

The photoconductive layer of the present invention contains at least a photoconductor and a binder, and the photoconductor may be either an inorganic material or an organic material. Examples of the inorganic photoconductive material include Si, Ge, zinc oxide, cadmium sulfide, titanium oxide, selenium, cadmium selenide, zinc selenide or lead oxide, Se—Te alloy, As ₂ S ₃ , As.
Examples include chalcogen alloys such as ₂ Se ₃ . Examples of the organic photoconductive material include photoconductive cyanine pigments, photoconductive quinoline pigments, photoconductive phthalocyanine pigments, photoconductive pyrylium salt pigments, substituted vinyl oxazoles, triphenylamine derivatives, anthracenes, and benzocondensates. Heterocycles, pyrazoline or imidazole derivatives, oxadiazole derivatives, vinyl aromatic polymers and their copolymerization products, fluorenone derivatives,
Polyarylalkanes such as triarylmethane leuco dyes and squaric acid derivative dyes, perylene, tetracene, carbazole, tetrabenzyl-p-phenylenediamine, squarylium, indigo, dimethylperimide, polyzenyltetracene, polyzenylperylene , it may be mentioned acyl hydrazone derivatives, Ben zo thiazole derivatives, tetracyanoethylene pyrene, those black Russian Blue and various. You may use these together. As the binder, use a material known as a binder for silicone resin, polystyrene, polyacrylic acid or polymethacrylic acid ester, polyvinyl acetate, polyvinyl chloride, polyvinyl butyral and their derivatives and other photoconductive layers. You can The amount of the photoconductor in the photoconductive layer is such that the weight ratio of the photoconductive substance to the binder is, for example, in the range of 3: 1 to 20: 1, but is not particularly limited in the present invention. .. Further, if necessary, a sensitizer and a coating aid and other additives used when coating can be added. The thickness of the photoconductive layer is usually about 2 to 20 μm, but is not particularly limited in the present invention. Further, in order to improve the adhesive force between the photoconductive layer and the under layer, the surface of the under layer is previously formed, for example, in US Pat.
As described in Japanese Patent No. 1,908, it is preferable to perform surface treatment such as corona discharge treatment, glow discharge treatment, flame treatment, ultraviolet treatment, ozone treatment, and plasma treatment.

The lithographic printing plate precursor according to the present invention may be produced by a technique known in the field of manufacturing electrophotographic lithographic printing plate precursors of this type, and examples of dispersion methods include a ball mill, a colloid mill, an ultrasonic disperser, and 3 This roll mill, grain mill,
A normal one such as a homogenizer or a homomixer can be used. As a coating method, an air knife coater,
A trailing grade coater, wire bar coater, reverse roll coater, kiss roll coater, fountain coater, etc. can be used.

The above-mentioned original plate of the present invention is made into a lithographic printing plate after undergoing usual processes such as charging, image exposure and development. Also,
In addition to the usual wet development, for example, Japanese Patent Application No. 63-89373.
It is also suitable for the development of a direct power supply system as described in Japanese Patent Publication No. Hei 2-132464.

[0017]

The present invention will be described below with reference to examples, but the present invention is not limited thereto. Example 1 A dispersion of SBR emulsion, poval (polyvinyl alcohol), clay, melamine, and water was applied to one surface of a high-quality paper having a basis weight of 100 g / m ² by using a wire bar, and the same was placed in an oven at 140 ° C. for 1 minute. Dry and apply 7g
An inner layer of the under layer of / m ² was provided. The amount ratio of the inner layer composition at this time is as follows. With regard to the SBR emulsion and Poval, the Young's modulus when the amount is used as the single film of the eye is from about 300 kg / cm ² to about 3000 k.
Adjust to change in 4 steps in the range of g / cm ² and 4
The types of samples (A), (I), (U), and (E) were obtained. Inner layer composition : SBR emulsion Appropriate amount Poval Appropriate amount Starch 3 parts by weight Clay 30 parts by weight Melamine 3 parts by weight Water 100 parts by weight

The single film of the composition for the inner layer is prepared by coating the dispersion of the composition on a glass support with a wire bar, air-drying and then drying in an oven at 140 ° C. for 1 minute to give a coating amount of 100 g / It is obtained by forming a m ² film and peeling it from the glass support.

Next, the outermost layer composition dispersion comprising a styrene-butadiene resin (hereinafter abbreviated as SBR) emulsion, clay, conductive titanium oxide, melamine, and water was applied on the inner layer using a wire bar, It was dried in an oven at 140 ° C. for 1 minute to provide an outer layer having a coating amount of 3 g / m ² . The amount ratio of the outermost layer composition at this time is as follows,
The amount of conductive titanium oxide is 4 when the surface resistivity ρs of the outer layer is in the range of about 1 × 10 ⁹ Ω to about 1 × 10 ¹² Ω.
Adjust so that it changes in stages, and
It was applied to each of (e), and four kinds of samples were prepared, for a total of 16 kinds of samples. Outer layer composition: SBR emulsion 23 parts by weight Clay 30 parts by weight Conductive titanium oxide Appropriate amount Melamine 2 parts by weight Water 100 parts by weight

On the back side of the paper which is the support of the above 16 kinds of samples, 25 parts by weight of SBR emulsion, 45 parts by weight of clay, 4 parts by weight of casein, 4 parts by weight of melamine and 1 part of water.
A coating solution of 100 parts by weight was applied using a wire bar and dried in an oven at 140 ° C. for 1 minute to apply a coating amount of 10
A back layer of g / m ² was provided. The results of measuring the Young's modulus and the surface resistivity of the outermost layer of the single film of the inner layer composition of the 16 kinds of samples thus obtained are summarized in Table 1.

[Table 1]

On the outer layer side of each sample (support) obtained above, 100 parts by weight of photoconductive zinc oxide, acrylic resin 20
3. 4 parts by weight, toluene 125 parts by weight, phthalic anhydride 0.1 part by weight, and rose bengal 4% methanol solution 4.
The dispersion liquid consisting of 5 parts by weight is applied using a wire bar, dried in an oven at 110 ° C. for 20 seconds, and the applied amount is 2
An electrophotographic photosensitive paper was prepared by providing a photoconductive layer of 5 g / m 2.
About this electrophotographic photosensitive paper Commercial electrophotographic plate making machine EL
2 using P404V (manufactured by Fuji Photo Film Co., Ltd.)
Under the environmental conditions of 0 ℃, 65% RH and 15 ℃, 30% RH
When development was performed and the fog in the non-image area was examined, the results shown in Tables 2 and 3 were obtained. Each symbol in Tables 2 and 3 means the evaluation of fog density as described below. ○: Fog density 0.6 or less △: 0.7 to 1.0 ▲: 1.0 to 1.4 ×: 1.5 or more When the fog density is higher than 0.7, stains occur during printing. Therefore, it is not suitable for practical use.

[0022]

[Table 2]

[0023]

[Table 3]

From the results shown in Tables 2 and 3, even under the more severe environmental conditions of 15 ° C. and 30% RH, the surface resistivity of the under layer can be controlled within the range of the present invention to obtain sufficient electron emission. It was confirmed that an area that satisfies photographic performance could be secured.

Next, the above (a-1 to 4) to (e-1 to
Commercially available yellow blood salt based etchant ELP-E
2 (Fuji Photo Film Co., Ltd.) is used for etching to form a printing plate, which is then applied to an AD-80 type printing machine (Ryobi Printing Co., Ltd.) to show the performance as a printing plate after printing 200 sheets. Table 4 shows the results of examining the plate out of print.

[0026]

[Table 4] In addition, each symbol of Table 4 shows the following evaluation results. ◯: No print cut, no cracks at all △: Print cut, cracks at least 1/3 of the whole ▲: Print cut, cracks at least 1/2 of the whole ×: Print break, completely cut It is not suitable for practical use if there is a print out.

The combined results of Tables 3 and 4 above are
As shown in Table 5, among the 16 types of samples, the samples with less fog and plate breakage are U-1, U-2, E-1, E-
2, that is, the surface resistance of the outer layer is 1 × 10 ¹¹ Ω or less and the Young's modulus of the inner layer is 10 which is limited to the present invention.
It is clearly understood that the range of 00 kg / cm ² or less is the range where the object of the present invention can be achieved.

[Table 5]

Example 2 In Example 1, an acrylic emulsion was used in place of the SBR emulsion used for the inner layer and the outer layer of the under layer, and the amount of poval was changed from the Young's modulus of the inner layer of about 400 kg / cm ^2. About 2000 kg / cm ²
The same procedure as in Example 1 was carried out except that the adjustment was made so as to be changed in three steps within the range. Inner layer composition: Acrylic emulsion 30 parts by weight PVA appropriate amount of starch and 3 parts by weight Clay 30 parts by weight of melamine 3 parts by weight of water 100 parts by weight outer layer composition: acrylic emulsion 23 parts by weight Clay 30 parts by weight conductive titanium oxide qs melamine 2 parts by weight of water 100 parts The results obtained by measuring the Young's modulus of the single film of the inner layer composition of the obtained 12 kinds of samples and the surface resistivity of the outer layer are shown in Table 6.
Are summarized in.

[Table 6]

When these samples were subjected to development (evaluation of fog) and printing test in the same manner as in Example 1, Table 7
The results shown in are obtained. Each symbol in Table 7 has the same meaning as in Tables 2 to 5.

[0030]

[Table 7] Of the 12 types of samples, the one with less fog and plate out,
KA-5, KA-6, KI-5, KI-6, that is, the surface resistance of the outer layer is 1 × 10 ¹¹ Ω or less and the Young's modulus of the inner layer is 1000 kg / cm ² or less, which is limited to the present invention. It is clearly understood that the range of is a region where the object of the present invention can be achieved.

Comparative Example 1 A dispersion of SBR emulsion, poval, starch, clay, melamine, and water was applied to one side of a high-quality paper having a basis weight of 100 g / m ² by using a wire bar, and then was placed in an oven at 140 ° C. for 1 hour. After drying for one minute, an undercoat layer having a coating amount of 15 g / m ² was provided. The amount ratio of the undercoat layer composition at this time is as follows. For the conductive titanium oxide, the amount ratio was adjusted so that the surface resistivity ρs of the undercoat layer was constant at 1 × 10 ⁹ Ω. , SBR emulsion and Poval have a Young's modulus of about 30 when they are used as a single film of the composition.
Attempts were made to adjust it so that it varied from 0 kg / cm ² to about 3000 kg / cm ² . However, the surface resistivity is 1
Young's modulus of 1000 kg / cm while keeping at × 10 ^9.
It could not be less than ² . Undercoat composition: SBR emulsion 30 parts by weight Poval proper amount starch 3 parts by weight clay 30 parts by weight melamine 3 parts by weight water 100 parts by weight SBR emulsion 25 parts by weight and clay 45 parts by weight on the back side of the paper which is the support for these samples. Parts by weight, 4 parts by weight of casein, 4 parts by weight of melamine and 100 parts by weight of water are applied using a wire bar and dried in an oven at 140 ° C. for 1 minute to give a back layer having an application amount of 10 g / m ² . Was established. Furthermore, 100 parts by weight of photoconductive zinc oxide, 20 parts by weight of acrylic resin, 125 parts by weight of toluene, 0.1 part by weight of phthalic anhydride, and 4% methanol solution of rose bengal on the undercoat layer. 5 parts by weight of the dispersion liquid was applied using a wire bar, and a photoconductive layer having an application amount of 25 g / m ² was provided in the oven at 110 ° C. for 20 seconds to prepare an electrophotographic photosensitive paper. A printing test was carried out on each of the obtained electrophotographic photosensitive papers in the same manner as in Example 1. However, no printing plate was found after printing 200 sheets.

[0032]

As described above, according to the present invention, the under layer has a multi-layer structure and the outermost layer has a surface resistivity of 1 ×.
The electrophotographic property, particularly the developing property, is secured at 10 ¹¹ Ω or less, and the Young's modulus of the inner layer is set to 1000 kg / cm ² or less to prevent plate breakage during printing and to achieve both electrophotographic property and printing property. It can be used as a lithographic printing plate precursor.

Claims (1)

[Claims] 1. An electrophotographic lithographic printing plate precursor comprising at least a photoconductive layer on one surface of a support and an underlayer provided directly below the photoconductive layer, wherein the underlayer comprises a plurality of layers. And the surface resistivity of the plurality of layers is 1 × 10 ¹¹ Ω.
An electrophotographic lithographic printing plate precursor having the following outermost layer and an inner layer having a Young's modulus of 1000 kg / cm ² or less.