JPH047557A - Electrophotographic planographic printing plate material for laser beam - Google Patents

Abstract

PURPOSE:To obtain the electrophotographic planographic printing plate material which is free from or less in printing staining by incorporating specific dye compds. as well as Co salt and Mn salt into a photoconductive layer. CONSTITUTION:This printing plate material has a base and the photoconductive layer which is formed on the surface of this base and contains a mixture composed of a photoconductive pigment and an electrical insulating binder as its essential component. The dye compds. expressed by formulas I and II as well as the Co salt and the Mn salt are incorporated into this photoconductive layer. In the formula I, R1, R2 denote one member selected from -CH3, -C2H5 and -H2-CH=CH2 groups respectively independently from the other; X denotes a halogen atom. In the formula II, m, n denote >=1 integer; R3 denotes one group selected from -SO3, -COO-, and -O-PO3H- groups; R4 denotes one member selected from a quaternary ammonium group and alkaline metal atom. The sensitivity of the resulted photoconductive layer is improved in this way and the sticking of toners to non-image parts is lessened. In addition, the fogging resistance is improved and, therefore, the good printed matter with which bright images are obtainable and which is lessened in the printing staining is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an electrophotographic lithographic printing plate material for use with laser light.

More specifically, the present invention relates to an electrophotographic printing plate material spectrally sensitized to semiconductor laser light.

[Conventional technology]

In recent years, with the development of small offset printing presses and automatic printing presses, the mainstream of light printing is shifting to offset printing.

Much research and development has been carried out on such offset printing plate materials, and various improved materials have been put into practical use.

Among these materials, electrophotographic lithographic printing original plates having a photoconductive layer mainly composed of zinc oxide are the mainstream of light printing plate materials because they are inexpensive and have a simple plate-making process. ing. To produce electrophotographic printing plates, the printing plate material is usually subjected to corona charging, exposure, development and fixing processes according to the desired pattern using a plate making machine, thereby imparting a desired pattern to the photoconductive layer. Methods of forming visible images are widely used.

The above development process includes a dry development method that uses a mixture of toner and a carrier such as iron powder, and a wet development method that uses a developer obtained by dispersing toner in an organic solvent such as a high-boiling petroleum solvent. be.

When plate making is performed using the wet development method described above, there are advantages such as good reproducibility of halftone image formation, excellent resolution, short plate making time, and no correction required for the formed image. be. For this reason, in Japan, a method for producing electrophotographic printing plates using a wet development method is widely used.

In the electrophotographic lithographic printing plate as described above, the photoconductive zinc oxide itself used as the photoconductive pigment has a sensitive wavelength range only in the ultraviolet region of 370 nm. For this reason, in electrophotographic lithographic printing plates and offset masters that utilize photoconductive zinc oxide, rosehengal, uranine, BPB ( Broadening the photosensitive wavelength range by adding a sensitizing agent such as bromophenol (phenol) nigrosine has been widely studied and implemented.

On the other hand, the electronic plate-making machine used for boat fishing exposes the manuscript to light with a halogen lamp, exposes the corona-charged printing plate material to the reflected light, and obtains the printing plate material through a development and drying process. ing.

With the recent development of computers, the so-called computer-to-plate movement is gaining momentum, in which computer data is edited on a CRT and plates are directly produced without making a hard copy.

The driving force behind the development of such technology has been the advancement of laser beams, and in particular, semiconductor lasers allow devices to be made smaller and are inexpensive.
Also, in recent years, plate making systems using semiconductor lasers have been developed, taking advantage of the fact that they can be directly modulated. Electrophotographic printing plate materials used for laser beams must be sensitive to long wavelength light from 700 to 11,000 nm.

As an electrophotographic photoreceptor having sensitivity in the wavelength range of semiconductor laser light, for example, Japanese Patent Application Laid-Open No. 57-4624
No. 5, No. 58-58554, No. 58-59453,
It is described in the same No. 59-22053, the same No. 59-78358, etc.

Such a zinc oxide-based electrophotographic photoreceptor is one in which a sensitizing dye such as a polymethine-based cyanine dye is blended into the electrophotographic layer to perform spectral sensitization to a long wavelength range.

However, as in these examples, when a sensitizing dye was only added, the sensitivity did not reach a practically sufficient level.

Therefore, consideration has been given to the further use of a sensitizing agent. As an example of using a sensitizing dye and a sensitizing co-agent in combination, JP-A-1-161253 discloses a type of polymethine cyanine dye having an alkylsulfonic acid group on the N-substituents of the dimethyl indole rings at both ends, and a sensitizing co-agent. A formulation is disclosed in which maleic anhydride is used in combination as the agent.

This method of chemical sensitization using sensitizing aids such as maleic anhydride and phthalic anhydride is well known as a technology for electrophotographic materials, but it is still at a fully satisfactory level. has not been reached.

[Problem to be solved by the invention]

The present invention provides an electrophotographic lithographic printing plate material that has high sensitivity to long-wavelength light of wavelengths 700 to 11,000 nm, and therefore has high sensitivity that is practical for use with semiconductor laser light, and has no or little printing stain. This is what we are trying to provide.

X represents a halogen atom] and [Means for Solving the Problems] The electrophotographic printing plate material for laser light of the present invention comprises a support, and and a photoconductive layer containing as a main component a mixture of a photoconductive pigment and an electrically insulating binder, the photoconductive layer having the following general formula (I
) and (■): [However, in the above formula, R,, R2 are each independently CI+3, C2115 and -CHz CH=CHz group [However, in the above formula, m,
n represents an integer of 1 or more, R3 bar 5O3e, -co
At least one member selected from the dye compounds represented by: oe, oyo, 10-PO3He group, and R4 represents one member selected from a quaternary ammonium group and an alkali metal atom.
and at least one member selected from Co salt and Mn salt.

The dye compound used in the present invention is selected from the polymethine cyanine dye compounds represented by the above general formulas (I) and (II).The dye compounds of the above formulas CI) and (n) have little dark decay and are thermally stable. It is characterized by good performance and sensitivity.

The total amount of dye compounds (I) and (U) contained in the photoconductive layer is 0.001 to 0.00% based on the weight of zinc oxide.
Preferably in the range of 5%, 0.01-0.2%
It is more preferable that it is in the range of .

The effect of adding Co salt and Mn salt is that the sensitivity of the resulting photoconductive layer is improved, toner adhesion to non-image areas is reduced, and fog resistance is improved, so that clear images can be obtained. Also, it is possible to obtain printed matter with good printing soiling. Examples of Co salts include cobalt chloride, cobalt bromide, cobalt fluoride, cobalt corate, cobalt naphthenate, and cobalt oxalate.

Further, examples of the Mn salt include manganese chloride and manganese naphthenate.

The Co salt and Mn salt used in the present invention may be used alone or in combination.

Further, the content of these metal salts is preferably in the range of 0.001 to 0.5% based on the weight of zinc oxide.

The photoconductive layer is generally formed by coating an intermediate layer with a paint consisting of a photoconductive pigment such as zinc oxide or titanium oxide, an insulating adhesive, a sensitizer, and a solvent, and then drying the coating. It is formed by

As the insulating binder for the photoconductive layer, generally used are acrylic ester copolymers, methacrylic ester copolymers, vinyl acetate copolymers, silicone resins, butyral resins, etc., which have good hydrophilic properties. Such hydrophilic resins are effective in preventing background smudges that occur during printing. These resins that are effective in preventing scumming are copolymerized with monomers having functional groups such as acrylic acid, methacrylic acid, and maleic acid in order to improve the image quality, physical properties of the paint, and mechanical strength of the paint film. It is normal to have Further, in order to prevent etching and curling of the printing plate material or to prevent penetration of toner during wet development, a back layer is usually formed on the opposite side of the photoconductive layer.

The solid content of the binder resin contained in the photoconductive layer is preferably 10 to 30% based on the weight of zinc oxide.
More preferably, it is within the range of 5%.

The support for the printing plate material of the present invention is water-resistant and is selected from paper, a laminated sheet of paper and aluminum foil or polyethylene film, plastic film, paper with a vapor-deposited metal layer, synthetic paper, etc. I can do it.

The thickness of the support is generally preferably about 100 to 170 mm.

An intermediate layer may be formed between the support and the photoconductive layer to improve the water resistance of the printing plate material.

Components forming such an intermediate layer generally include water-soluble polymers such as polyvinyl alcohol, casein, and starch, and synthetic resins such as acrylic ester copolymers, urethane-acrylic ester copolymers, and 5BR1. emulsion and melamine-formaldehyde resin,
Water resistance agents such as glyoxal and silane coupling agents are used. The middle layer is generally 5 to Log
/n(dry weight).

In order to produce the printing plate material of the present invention, an intermediate layer coating material containing necessary components and a solvent is coated and dried on one surface of the support, and the intermediate layer paint is coated on the intermediate layer or on the support. A photoconductive layer coating containing the required components and a solvent (for example, ethyl acetate, butyl acetate, toluene, or xylene) is applied directly onto the surface and dried, and then a back layer coating containing the required components is coated on the support. Just apply it to the back side and let it dry.

〔Example〕

The present invention will be further explained below with reference to Examples.

An electrophotographic printing plate material was prepared by the following steps (I) to (5), a printing plate was made from it, and its properties were measured and evaluated in step (6).

(I) A barrier layer having the following composition was formed on one side of a base paper having a basis weight of 100 g/n (dry coating weight) by size press treatment to a weight of 2 g/n (dry coating weight).

Polyvinyl alcohol 80 parts (solid weight) Sodium polyacrylate 20 parts (〃〃) (2) Above sizes/
An intermediate layer paint having the following composition was applied to the barrier layer surface of a press-treated base paper (thickness: 110 t!m) and dried to form an intermediate layer with a dry coating weight of 10 g/n.

Interlayer-forming muscovite. , 40 parts (by weight) aqueous polyurethane dispersion. , 2 40 parts (〃) Casein aqueous solution 10 parts (〃) Silane coupling agent (ar 3 10 parts (〃) Note., 1... Trademark: A-21, manufactured by Yamaguchi Mica Co., Ltd., average particle size: 20 cm c) 2... Trademark: Azerax S-1071, manufactured by Hodogaya Chemical Co., Ltd. (*) 3... Trademark: 5H6040, manufactured by Toshi Silicone Co., Ltd. (3) Apply a paint with the following composition on the back side of the above support. - It was dried to form a conductive paint back layer with a dry coating weight of 13 g/rd.

Kaolinite clay dispersion. , 5 SBR latex

Polyvinyl alcohol (*) 7 Sodium polyacrylate (monkey) 8 Note. 4...Trademark: Eposter L Manufactured by Nippon Shokubai Chemical Co., Ltd. (*) S'' Trademark: HG Clay (USA) tlube
Manufactured by r company. , 6... Trademark: PT-1004 manufactured by Nippon Zeon Co., Ltd. (*) 7... Trademark: T-330 manufactured by Nippon Gosei Kagaku Co., Ltd. (Syn) 8... Trademark NIBRIMAR 850 manufactured by Nippon Acrylic Co., Ltd. 50 parts (35 parts) (7 parts (3 parts) After forming the intermediate layer and the conductive paint back layer on the support, supercalender treatment was performed so that the surface smoothness of the intermediate layer was 500 seconds in terms of Oken Beck smoothness.

(4) On the surface of the intermediate layer, a photoconductive layer paint having the following composition was applied and dried to form a photoconductive layer with a dry coating weight of 25 g/n.

Photoconductive zinc oxide (9100 parts (by weight)) Silicone resin, 1825 parts (〃) Manganese chloride 0.05 parts (〃) Note.

, 9... Trademark: 5AZEX #2000 Sakai Chemical, Yu5. . ... Trademark: KR-683 Shin-Etsu Chemical To this mixed solution, add the compound of general formula (I) [however, R1 in formula (I)
, R2 all represent CH3, and X represents an I atom]
A solution prepared by dissolving 0.02 part of a sensitizing dye compound consisting of the following in 3 parts of methanol was added, and this mixed solution was dispersed with a sand glider to obtain a coating solution.

After conditioning the resulting printing plate material for 24 hours in a dark place at 20°C and 265%RH, the surface of the photoconductive layer was coated with
After negative corona charging, semiconductor laser light (laser intensity: 4, 5 or 6 mL, wavelength: 78
0 nm), scanning exposure was performed at 430 dpi. Next, this exposed surface was developed using a positively charged liquid toner (manufactured by Itek).

In the printing test, an etch solution from Itek was used as an etchant, and a 10-fold dilution of the etch solution from Itek was used as a dampening solution. Further, New Champion De Gloss Sumi (Dainippon Ink) was used as the printing ink, and the developed printing plate was mounted on a printing machine (Ryobi 2800CD) to perform printing.

The printing characteristics of the test printing plate were evaluated by observing the printing surface stain caused by the toner remaining on the plate during exposure at the three laser intensities described above. The results are shown in Table 1.

Plate making quality (61) was measured as follows.

Example Coal I The same operation as in Example 1 was performed. However, cobalt chloride was used instead of manganese chloride.

The evaluation results are shown in Table 1.

The same operation as in Example 1 was carried out. However, manganese naphthenate was used instead of manganese chloride.

The evaluation results are shown in Table 1.

A Certain Fifty Juice The same operation as in Example 1 was performed. However, as a sensitizing dye compound, a compound of the general formula (n) [however, m in formula (II)]
, n each represent an integer 3, R3 represents a -SO3θ group, and R4 represents a -HN(CJs)+ group]
It was used.

The evaluation results are shown in Table 1.

The same operation as in Example 1 was carried out on the rattan base. However, as the metal salt, a total of 0.05 part of a mixture containing the same amounts of cobalt bromide and manganese chloride was used.

The evaluation results are shown in Table 1.

The same operation as in Example 1 was performed. However, as an aggravating pigment compound, a compound of general formula (I) [however, R,,R in formula (I)
, each represents a -CH group, and X represents an I atom)
0.01 part of a dye compound consisting of
represents a -803e group, and R4 is -11N(C2H5)
Table 1 shows the evaluation results using 0.01 part of a dye compound consisting of 3].

North Korea flames out The same operation as in Example 1 was performed.

However, a compound having the following structural formula was used as a sensitizing dye compound.

The evaluation results are shown in Table 1.

Comparison I The same operation as in Example 1 was performed.

However, a photoconductive layer coating was produced without using manganese chloride.

The evaluation results are shown in Table 1.

The electrophotographic lithographic printing plate materials shown in Tables 2 to 2 had insufficient sensitivity to semiconductor lasers, and when used as printing plates, the printing surface was severely smudged, making them impractical as printing plate materials.

Note) ○ (good), △ (slightly bad), × (bad), ×× (
It was rated on a four-point scale (very poor).

As shown in Table 1, the electrophotographic printing plate materials of Examples 1 to 6 according to the present invention have high sensitivity to semiconductor laser light, and the printing test The stain resistance was also good. On the other hand, Comparative Example 1 [Effect of the Invention] The electrophotographic lithographic printing plate material of the present invention exhibits high sensitivity to semiconductor laser light and can be used as a printing plate material to produce a printing plate material free from printing background stains. It is suitable for

By using the electrophotographic printing plate material of the present invention, it becomes possible to digitize printing plate making, and therefore,
This makes computer-to-plate possible and is extremely useful in practice.

Claims (1)

[Scope of Claims] 1. Comprising a support and a photoconductive layer formed on the surface of the support and containing a mixture of a photoconductive pigment and an electrically insulating binder as a main component, The photoconductive layer has the following general formulas (I) and (II): ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (I) [However, in the above formula, R_1 and R_2 each independently represent -CH_3, - C_2H_5 and -CH_2-
Represents one member selected from the CH=CH_2 group, and X represents a halogen atom] and ▲ Numerical formulas, chemical formulas, tables, etc. ▼ (II) [However, in the above formula, m and n represent integers of 1 or more. , R_3
are -SO_3^■, -COO^■, and -O-PO_
3H^■ represents one member selected from the group, R_4 represents one member selected from the quaternary ammonium group and an alkali metal atom
1. An electrophotographic lithographic printing plate material for laser light, characterized in that it contains at least one member selected from Co salt and Mn salt.