JPS6015648A - Electrophotographic lithographic original plate - Google Patents

Abstract

PURPOSE:To obtain an original plate having superior resistance to org. solvent of a precoat layer and printing durability, good coatability, and small age deterioration by using a specified quadripolymer as a resin for the precoat layer. CONSTITUTION:A quadripolymer made from 100pts.wt. acrylate, 20-100pts.wt. acrylonitrile, 0.5-50pts.wt. monomer having an epoxy group, and 0.5-50pts.wt. polymerizable unsatd. carboxylic acid is used as the resin for a precoat layer of a zinc oxide photosensitive material type original plate. Said copolymer is preferably prepared by emulsion polymerization of said monomers.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to an original plate for electrophotographic lithography that is made by an electrophotographic method.

Prior Art An original plate for electrophotographic lithography is generally prepared by sequentially providing a resin precoat layer and a zinc oxide/resin binder dispersed photosensitive layer on the other side of an isoelectric support such as paper or plastic film that has been conductively treated on one side. The resins used in the precoat layer include acrylic ester-acrylonitrile copolymer (the ratio of acrylonitrile is 20 parts by weight or less per 100 parts by weight of acrylic ester), styrene-acrylic ester coelectropolymer, and polyacetic acid ester. 2 vinyl, styrene-butadiene copolymer, methyl methacrylate-butadiene copolymer.

E17 Thermoplastic emulsion resin such as vinyl chloride (
They are broadly divided into two types: mixed systems (resins used in an emulsion state during use) and water-soluble resins such as polyginyl alcohol and starch, and thermosetting emulsion resins such as alkyd resins, phenolic resins, and epoxy resins. Ru. However, when the above conventional mixed system of thermoplastic emulsion resin and water-soluble resin is used for the precoat layer, it is good in terms of continuous film formation, but the conventional emulsion resin is soluble in organic solvents. Therefore, a product with poor organic solvent resistance is obtained. The precoat layer needs to have organic solvent resistance because a photosensitive layer forming liquid containing an organic solvent is applied onto the precoat layer. If the organic solvent resistance of the precoat layer is poor as described above, coating unevenness is likely to occur when applying the photosensitive layer forming liquid (
As a result, the electrophotographic properties of the obtained original plate are significantly deteriorated, resulting in quality and practical problems such as insufficient image density and increased pre-exposure fatigue. Conventionally, attempts have been made to compensate for this by increasing the proportion of water-soluble resin or adding a cross-linking agent such as an aqueous formaldehyde solution, but the former method uses a large amount of water-soluble resin. As a result, the printing durability of the original plate decreases, and since the latter method involves high heat treatment for crosslinking, formaldehyde is generated during heating and deterioration over time (discoloration, decreased sensitivity, insufficient image density), etc. Another disadvantage arises. On the other hand, when a thermosetting emulsion resin is used for the precoat layer, it is difficult to obtain a continuous film, so a large amount of coating is required, and cracks and pinholes occur after applying the photosensitive layer forming liquid. However, the quality of what can be used is limited.

Purpose The purpose of the present invention is to provide a precoat layer with excellent organic bath agent properties.
Therefore, it is an object of the present invention to provide a high-quality original plate for electrophotographic printing that has good coating properties, excellent printing durability, and little deterioration over time.

Structure The original plate of the present invention is an original plate for electrophotographic lithography in which a resin precoat layer and a zinc oxide/resin binder dispersion photosensitive layer are sequentially provided on the other side of a support whose one side is conductively treated.
Zoreko) as % resin (,) acrylic/l' [ester 10' O weight:! a1 part and (b) acrylonitrile 20~Zoo Jusha part and (c) epoxy group-containing monomer 0
．． It is characterized by using a quaternary copolymer of 5 to 50 parts by weight and 05 to 50 parts by weight (dl)'F-combinable unsaturated carbene.

The quaternary copolymer used in the precoat layer of the present invention is 20 to 100 parts by weight (preferably 30 parts by weight) of acrylonitrile per 100 parts by weight of alkyl ester of acrylic acid.
~80 parts by weight), epoxy group-containing monomer 0.5-50
It is made by copolymerizing, preferably emulsion polymerizing, parts by weight (preferably 1 to 20 parts by weight) and 05 to 50 parts by weight (preferably 1 to 20 parts by weight) of polymerizable unsaturated carginic acid.

The acrylonitrile component in the copolymer thus obtained has the effect of imparting organic solvent resistance to the copolymer because it is stable against organic solvents and oils, and the acrylic ester component has the effect of imparting organic solvent resistance to the copolymer. It is the main component and has the effect of imparting water resistance and adhesion to the copolymer, and the epoxy group-containing monomer and polymerizable unsaturated carzenic acid are the main components of the copolymer. The crosslinking has the effect of improving not only the organic solvent resistance but also the water resistance of the copolymer. Examples of the alkyl ester of acrylic acid include ethyl acrylate and butyl acrylate. Examples of the epoxy group-containing monomer include glycidyl acrylate, glycidyl methacrylate, and allyl glycidyl ether. Examples of the polymerizable unsaturated carzenic acid include maleic acid, maleic anhydride, itaconic acid, itaconic anhydride, and monomethyl itaconate. Note that if the ratios of acrylonitrile, epoxy group-containing monomer, and polymerizable unsaturated cardin branch to the acrylic ester in the copolymer are outside the specified ranges, it may be difficult to obtain the above-mentioned effects. Become.

A water-soluble resin or an inorganic pigment can be added to the precoat layer of the present invention, if necessary. The appropriate amounts to be added are 9 parts by weight or less of the water-soluble resin and 15 parts by weight or less of the inorganic pigment, respectively, per 1 part by weight of the copolymer.

Examples of water-soluble resins include polyvinyl alcohol, starch, gum arabic, casein, alginic soda, calxoxymethylcellulose, and methylcellulose.

Inorganic pigments include carbonates such as Ca, Ba, and Pb; oxides such as Zn, TI, Si, and Pb; Al, and Zn.
Hydroxides such as; Sulfates such as Zn, Ca, Ba; Si
, silicates such as AI; sulfides with Ba, Ca, Zn, etc.;
An example is Carzen Black.

The conductive treatment of the support is carried out in the same manner as before, by applying various conductive agents on paper or plastic films, water-soluble resins or emulsion resins as mentioned above, and if necessary, inorganic pigments such as calcium carbonate, clay, talc, titanium oxide, zinc oxide, etc. This is done by coating and drying an aqueous solution containing dissolved or dispersed water.

The photosensitive layer is the same as the photosensitive layer in general electrophotographic photosensitive materials, and includes, for example, polybutyl methacrylate,
It has a form in which zinc oxide and, if necessary, a dye sensitizer are dispersed in an insulating resin such as polyacrylic acid ester, polyvinyl chloride, polyvinyl acetate, polystyrene, silicone resin, or polyvinyl butyral. The appropriate amount of resin in the photosensitive layer is 15 to 25 parts by weight per 100 parts by weight of zinc oxide.

To make the original plate of the present invention, an aqueous dispersion containing a quaternary copolymer as a product is coated on the non-conductive surface of a conductive support and dried to form a precoat layer with a coating weight of about 5 to 159/lrl. An organic solvent dispersion containing zinc oxide and an insulating resin as main components may be coated thereon and dried to form a photosensitive layer with a coating weight of about 20 to 30 ///d.

Using the master plate obtained in this way, a lithographic printing plate (master) is created.
In order to obtain
That is, after the photoconductive layer is uniformly charged in a dark place, it is exposed imagewise to form an electrostatic latent image, which is developed with a lipophilic toner developer and the toner image is fixed. Next, this may be treated with a desensitizing solution. Such plate making can be easily carried out using a dry or wet electrophotographic plate making machine.

Furthermore, if the master thus created is subjected to printing, a large number of clear printed matter can be obtained. This is because the emulsifying quaternary copolymer resin contained in a large amount in the precoat layer does not dissolve or swell with organic solvents during photosensitive Ri removal, so a photosensitive layer without uneven coating can be formed.
This is believed to be because, as a result, image density, pre-exposure fatigue characteristics, etc. can be maintained at a high level.

Examples of the present invention are shown below. Note that all parts are parts by weight.

Example I Bog/lr? A quaternary copolymer of 65 parts of acrylic string JN, 35 parts of acrylonitrile, 5 parts of glycidyl methacrylate, and 5 parts of methacrylate/L[t] was coated on one side of high-quality paper.
5. Aqueous emulsion 100 parts polyvinyl alcohol (degree of polymerization 17oo).

A solution consisting of 450 parts of a 10% aqueous solution with a sulfur content of 98 to 99 moles was coated with a wire parlor and dried until the amount of adhesion was about 1 liter.
After providing a precoat layer of og/go, 100 parts of polyvinyl alcohol (Kuraray Bhopal 117, manufactured by Kuraray Co., Ltd.) '4't JL agent (manufactured by Dow Chemical Company, ECR-77) was applied to the opposite side.
A solution consisting of 30 parts water and 1200 parts was applied with a wire spar and dried to form a conductive treatment layer with a light-applied thickness of about 5 g/m'.

Further, on the pre-coat layer, a solution consisting of 200 parts of zinc oxide (Sazetsu 4'4000, manufactured by Yo Kagaku Co., Ltd.), 40 parts of silicone resin (KR-211, manufactured by Shin-Etsu Chemical Co., Ltd.), 0.1 part of rose bengal, and 200 parts of toluene was applied. It was coated with a wire parser and dried to form a photosensitive layer with an adhesion amount of about 2 s 11/rl, thereby producing a 1 (i) photolithographic printing original plate.

Example 2 Electron copolymers were prepared in the same manner as in Example 1, except that a quaternary copolymer consisting of 65 parts of butyl acrylate, 35 parts of acrylonitrile, 10 parts of glycidyl methacrylate, and methacrylate and FI/filO parts was used. Created a master plate for photolithographic printing.

Example 3 Electrophotolithography was carried out in the same manner as in Example 1, except that a quaternary copolymer consisting of 65 parts of butyl acrylate, 35 parts of acrylonitrile, 20 parts of glycidyl methacrylate, and 20 parts of methacrylate/I/acid was used. I made the original version for printing.

Example 4 Electrophotographic lithography was carried out in the same manner as in Example 1, except that a quaternary copolymer consisting of 65 parts of acrylic/I/zotyl acid, 35 parts of acrylonitrile, 5 parts of glycidyl methacrylate, and 5 parts of itaconic acid was used. I made the original version for printing.

Example 5 An original plate for electrophotographic lithography was prepared in the same manner as in Example 1, except that a quaternary coelectrolyte consisting of 65 parts of butyl acrylate, 35 parts of acrylonitrile, 5 parts of glycidyl methacrylate, and 2xo parts of itacon was used. Had made.

Comparative Example 1 An original plate for electrophotographic printing was prepared in the same manner as in Example 1, except that a quaternary covalent polymer consisting of 65 parts of ethyl acrylate, 35 parts of acrylonitrile, 1 part of methacrylic acid, and 10 parts of styrene was used. made.

Comparative Example 2 65 parts of butyl acrylate, 35 parts of acrylonitrile, 10 parts of acrylic acid and 1 part of methacrylic acid as a quaternary copolymer
An original plate for electrophotographic lithography was prepared in the same manner as in Example 1, except that 0 copies were used.

Comparative Example 3 An original plate for electrophotographic printing was prepared in the same manner as in Example 1, except that the copolymer of Example 1 except that the amount of the acrylonitrile component was changed to 15 parts was used as the quaternary copolymer.

Comparative Example 4 An original plate for electrophotographic lithography was prepared in the same manner as in Example 1, except that the quaternary copolymer used was the same as that of Example 3 except that the amount of acrylonitrile component was changed to 10 parts.

Comparative Example 5 An original plate for electrophotographic lithography was prepared in the same manner as in Example 1, except that the copolymer of Example 2 with the acrylonitrile component removed (ternary copolymer) was used as the quaternary copolymer. did.

Next, each of the above samples was processed using a commercially available dry electrophotographic engraving machine.
The plate was made in an atmosphere of 0° C. and 65% RH, and the image density of the obtained master (density of the 35-angle image) was measured using a Macbeth reflection densitometer.

Further, Sansol was pre-exposed at 2000 lux/second in an atmosphere of 20° C. and 65 inches RH, and the plate was made in the same manner, and the rjM image quality was measured. On the other hand, coating unevenness (streaks caused by wire paring) during coating of the photosensitive layer was visually evaluated, and the organic solvent resistance of the precoat layer was evaluated by dropping one drop of toluene on the precoat layer before coating the photosensitive layer. After a few seconds, it was wiped off with absorbent cotton and the degree of solubility was determined by visual evaluation. Furthermore, in order to examine the printing durability, each of the above masters was printed on a commercially available offset printing surface, and the number of prints until the image (characters) on the photosensitive layer peeled off was counted.

The above results are shown in the table below.

*l; ◎Not affected at all ○: Not affected △: Slightly affected As can be seen from the above, the product of the present invention using the emulsifying quaternary copolymer of the present invention has extremely good organic solvent resistance in the precoat layer, does not cause unevenness during coating, and therefore has a lower image density than the pre-exposure. Fatigue is also at a significantly higher level than comparative products.

In addition, if a large amount of such an emulsifying copolymer having good organic solvent resistance is used in the printing, the printing durability of the master can be further improved.

Claims (1)

[Claims] 1. In an original plate for electrophotographic printing, in which a resin precoat layer and a zinc oxide-resin binder dispersion photosensitive layer are sequentially provided on the other side of a support whose one side has been subjected to 4-electrode treatment, (al-acrylic acid Esthetics/I/100
parts by weight, (b) 20 to 100 parts by weight of acrylonitrile, (C) 0.5 to 50 parts by weight of a monomer containing an I-oxy group, and (
d) J! An original plate for electrophotographic printing, characterized in that it uses a quaternary copolymer with 0.5 to 50 parts by weight of synthetically unsaturated carzenic acid.