JPS61185493A - Original form for direct lithography printing - Google Patents

Abstract

PURPOSE:To enable to form an image free of unsatisfactory transferring or spreading of tone smear on texture, or image distortion during PPC processing by specifying volume resistivity of an original form for direct lithography printing to be in the scope of 10<10>OMEGAcm or above and less than 10<13>OMEGAcm. CONSTITUTION:The face dimension of the original form for direct lithography printing consists mainly of water soluble resin, pigments and water resisting agent; and its reverse dimension consists mainly of water soluble or emulsion type resin and pigments; and the medium layer mainly consists of water soluble or emulsion type resin, pigments and water resisting agent. Electrically conductive agents to be used are, in case of an inorganic group, metal salts of monovalence or polyvalence such as Na, K, Li, Mg, Zn, Co, Ni, and etc., and in case of organic group, high polymer cationic conductive agents such as polyvinyl benzyltrimethyl ammonium chloride, acrylic resin denatured fourth grade ammonium salt and etc. or high polymer anionic conductivity agents such as high polymer sulfonate, and the volume resistivity of the original form is set to stay within the scope of 10<10>OMEGAcm or over, and under 10<13>OMEGAcm.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a direct-plated lithographic printing original plate, and more particularly to a lithographic printing original plate suitable for PPC plate making.

Conventional technology The master plate for direct-plating planographic printing is pencil, I-lepen, ppc (
A type in which a plate is made by directly drawing or printing on the surface layer using a plain paper copying machine), a typewriter, a wire tod printer, a thermal transfer printer, etc., or by transferring a preformed toner image tube onto a photoreceptor. It's something.

Generally, a surface layer is provided on one side of a support such as paper or plastic film, or if necessary, via an intermediate layer for the purpose of improving water resistance, and a back layer is provided on the other side for the purpose of preventing curling. It is configured with the following. Here, the surface layer is formed from a water-soluble resin, a crosslinking agent for making it water-resistant (hereinafter referred to as a water-resistant agent), and a pigment, and the back layer is formed from a water-soluble resin or emulsion resin and, if necessary, a pigment. The intermediate layer is formed from these resins, pigments, and, if necessary, a waterproofing agent. These direct-draw planographic printing plates are highly water-resistant, so they have excellent printing durability, and their electrical resistance is as high as 1 billion to 100 million yen in volume resistivity. efficient,
Therefore, although it is possible to form a high-density image with no unevenness, the background smear on the photoreceptor is also transferred as is, so there is a lot of background smudge, and when one image is transferred, toner scattering and image distortion occur.
The drawback was that clear images could not be obtained. Furthermore, these drawbacks are particularly severe in low humidity environments where electrical resistance increases.

Object The object of the present invention is to provide an original plate for direct plate printing that can improve background smear, toner scattering, and image distortion during image transfer in conventional PPC plate making.

Structure The lithographic printing original plate of the present invention is a direct drawing lithographic printing original plate in which a surface layer is provided directly on one side of the support or via an intermediate 1, and a back layer is provided on the other side, and the volume of the original plate is It is characterized by having a specific resistance of 10111Ω or more and less than 1013Ω. The volume resistivity is measured by JI
The sample was tested at 20° C. and 65% RH in accordance with JI8-P-8111, and the test was conducted mutatis mutandis in accordance with JI8-C-2122.

The present inventors investigated the relationship between the volume resistivity of the master plate and RPC plate making/image transfer in order to improve the drawbacks of the conventional direct plate lithographic printing master plate, and found that the volume resistivity was lol@Ωα
If it is less than 10Ω scratches, it may cause background stains, image distortion, or
Image transfer is practically possible with almost no toner scattering, but image transfer is not possible with less than 1o1eΩ flaw, and with more than 1OIIΩ flaw, background stains,
If you find that image distortion, toner scattering, etc. are severe,
We have arrived at the present invention.

In the present invention, the volume resistivity of the master plate for direct lithographic printing is 10
Addition of a conductive agent, use of a low-resistance resin binder, etc. can be used to achieve a range of 1@Ω flaw or more and less than 1 mΩ flaw, but generally a method of adding a conductive agent is adopted. In this case, the conductive agent may be added to at least one of the surface layer, the back layer, the intermediate layer if necessary, and the support. Usually, the conductive agent is added to each layer of the surface layer, the back layer, and the intermediate layer if necessary. It is. The conductive agent may be inorganic or organic, and inorganic materials include Na, K, etc.
, Li, Mg, Zn, Co, Ni
Salts of monovalent or polyvalent metals such as polyvalent metal salts, and organic salts such as poly-nylbenzyltrimethylammonium chloride,
Examples include polymer cation conductive agents such as acrylic resin-modified quaternary ammonium salts and polymer anion conductive agents such as polymer sulfonate salts. These conductive agents are added in an amount such that the volume resistivity of the original plate falls within the predetermined range. Specifically, it varies depending on the type of conductive agent, the place where it is added, the amount of layer adhesion, etc., but when it is added to each of the above 1, it is 5% or more and less than 4096, preferably 10 to 30% of the resin component in each layer. be. In this case, if the amount added is less than 5 degrees, the above purpose cannot be achieved, and if it is more than 4 degrees, the electrical resistance becomes too low and P
During PC plate making, image transfer defects occur.

The surface layer, back layer and intermediate layer of the present invention have exactly the same structure as the conventional structure except for the conductive agent. That is, the surface layer is a water-soluble resin,
The main components are St additive and water resistant agent, the back layer is mainly composed of water-soluble or emulsion resin and pigment if necessary,
The intermediate layer is mainly composed of a water-soluble or emulsion resin, a pigment, and, if necessary, a water-resistant agent.

Here, the water-soluble resin is Pvum, starch or its 154
body, CMC, hydroxyethyl cellulose casein,
Gelatin, polyvinylpyrrolidone.

Styrene-maleic acid copolymers, etc. are used as emulsion resins, polymers or copolymers of vinyl acetate, vinyl chloride, acrylic esters, styrene, butadiene, ethylene, etc. are used as pigments, and clay, calcium carbonate, silica, etc. are used as pigments. , rR titanium, zinc oxide, palicum sulfate, alumina, etc., and water-resistant agents include melamine/formaldehyde resin initial condensate, urea/formaldehyde resin initial condensate, methylolated polyamide resin, polyamide ♂
Examples include chlorohydrin resin, modified polyamide polyimide resin, and the like.

Note that the amounts of pigment and water resistant agent used in the surface layer vary depending on the materials used, but are generally 50 to 5 oon and s to 9 oon, respectively.
0% is suitable, and the amount of pigment used in the intermediate layer is generally tcso~5GG%.

All conventional supports can be used, such as high-quality paper, wet-strengthened paper, polyester fiber, and muno5.
Examples include plastic films.

Generally, to make the lithographic printing master plate of the present invention.

If necessary, an aqueous solution containing an intermediate layer component is coated on one side of the support and dried to form an intermediate layer, and then an aqueous solution containing a surface layer component is coated and dried to form a surface layer, and then the other side is coated with an aqueous solution containing an intermediate layer component and dried to form an intermediate layer. The back layer may be formed by applying an aqueous liquid containing back layer components to the surface and drying it.

The adhesion amount of the different surface layer, back layer, and intermediate layer is 1 to 5 ot each.
t7ze, l~Bog/wl, and BN20 F/ze are suitable.

Examples of the present invention are shown below. All divisions, sections, and ratios are based on weight.

Examples 1 to 4 An aqueous solution with the following formulation was applied to both sides of 8097-free paper, dried at 130°C for 2 minutes, and the amount of adhesion was logl.
A back layer and an intermediate layer of d were formed.

(Left below) Next, apply an aqueous solution with the following formulation on this intermediate layer,
After drying at .degree. C. for 2 minutes to form a surface layer with a coating weight of 41/d, a suit blue calendering process was performed to prepare a direct drawing black lithographic printing original plate.

(Margins below) Next, the volume resistivity of each original plate was measured at 20°C and 65% RH, and then PPC plate making was performed to make a printing plate.
When offset printing was performed on 00 sheets, the results shown in the table below were obtained.

Note) O: Rarely occurs.

Δ: So small that there is no problem in practical use.

×: Generated in large quantities.

Examples 5-7 Chemistry) Instead of 6120, Nack! (Example 5), Zn (C retirement mO*)t (Example 6), C
An original plate for direct lithographic printing was prepared in the same manner as in Example 2 except that o3O4 (Example 7) was used. The volume resistivity of the printing original plates of Examples 5 and 6.7 is 4.2X1, respectively.
0"Ωam, 5.lXl0"Ωcm, 9.2X10"Ω
It was me. Next, when these printing original plates were made into printing plates by PPC platemaking and offset printing was performed on 500 sheets, printed matter with little background smudge was obtained as in Example 2, and there was also little toner scattering.

Example & 110Ii/1! ? The back layer formulation solution of Example 2 was applied to one side of the wet reinforced paper to form a back layer having a coating amount of log/-. Next, an aqueous solution having the following formulation was applied to the opposite side of the back side and dried to form a surface layer of zoi7-, and then the suit was calendered once to obtain a printing original plate.

Surface layer formulation The volume resistivity of this printing plate at 20°C, 65% R) I was 3 x 10”Ω1. Next, this printing plate was coated with P
PC plate making to make a printing plate and offset printing 1
000 prints with little background staining were obtained.

Example 9 An aqueous solution consisting of the following formulation was applied to both sides of Rolld's high-quality paper, dried at 130°C for 3 minutes, and the coating weight was 1.
A middle layer and a back layer of sl/ll, 101/m' were formed.

Intermediate layer and back layer formulation: pvAoxo% aqueous solution 45o parts Melamine formaldehyde resin initial combination (solid content 80%) 125 parts NH4
CJ 2 o % aqueous solution 4 parts water 243 parts Next, the aqueous solution for surface layer of Example 1 was applied on the intermediate layer, and 130 parts
It was dried at ℃ for 3 minutes to form a surface layer of 411/ze. Furthermore, a printing original plate was obtained by super calendering. The volume resistivity of this product at 20℃ and 654RH is 8X
It was 10Ω.

Next, this printing original plate was made into a printing plate using a PPC plate, and when offset printing was performed, 800 prints with little background staining were obtained.

Example 10 An aqueous solution consisting of the following formulation was applied to the intermediate layer surface of the same support as in Example 1, and dried at 130°C for 3 minutes to achieve a coating weight of 181.
1/11? A surface layer was formed, and a printing original plate was obtained by applying a suno-saw calender.

Surface r-formulation: 20% aqueous dispersion of silica 400@PVA 1
0% aqueous solution 500 parts modified polyamide resin
167 parts NH4Cl f) 20% aqueous solution 4s water
218 parts The volume resistivity of this product at 20@C and 65% RH was 9 x 1010 Ωcm. Next, this plate was made into a printing plate by '6RPC, and when offset printing was performed, 500 prints with little background smudge were obtained.

Effects As described above (by specifying the volume resistivity of the original plate for direct seeding planographic printing of the present invention in the range of 10Ω or more and less than 1013Ωα, transfer defects of one image and toner scattering can be almost eliminated during PPC plate making. It has the advantage that it is possible to form a 1ltIl image without any background stains or distortions, and therefore, when the printing plate thus obtained is used for printing, clear printed matter can be obtained.

Claims (1)

[Claims] 1. In a direct drawing type lithographic printing original plate in which a surface layer is provided directly or through an intermediate layer on one side of the support and a back layer is provided on the other side, the volume resistivity of the original plate is 10^1^ 0Ωc
An original plate for direct drawing type lithographic printing, characterized in that it has a resistance of Ωm or more and less than 10^1^3 Ωcm.