JPS63226658A - Planographic printing material for back exposure - Google Patents

Abstract

PURPOSE:To obtain the titled material having excellent fine line reproducibility by incorporating an antihalation agent which imparts 0.1-0.5 transmission density to the material and matting agent having 2-10mum average grain size into an under coating layer. CONSTITUTION:The matting agent of 2-10mum is used in the under coating layer in order to execute planographic printing utilizing a silver complex salt diffusion method for back exposure with high plate wear, high water retentivity, hard contrast in photographic characteristic, excellent fine line reproducibility and high quality. The optical density of the antihalation under coating layer is required to be set at 0.1-0.5. The sufficient fine line reproducibility and printing resistance are not obtainable at <=0.1. The photographic characteristic is softened in contrast and various problems arise at <=0.5. Carbon black is preferably used in a 1-5wt.% range with respect to a binder as the antihalation agent. Silica particles having 4-10mum average grain size are used as the matting agent.

Description

DETAILED DESCRIPTION OF THE INVENTION (A) Industrial Field of Application The present invention relates to a lithographic printing material using a silver complex diffusion transfer method (DTR method).

(B) Prior art and its problems Planographic printing materials using the DTR method, specifically, at least one photosensitive layer on a support and an image photosensitively recorded on the photosensitive layer on the support should be inverted and transfer-recorded. A lithographic printing material obtained by image-freeing a material consisting of a layer of physical development nuclei and then subjecting it to a silver diffusion transfer development process to form a metallic silver image on the outer surface of the core material can be obtained using the direct plate making method. It has the advantages of simplicity and speed compared to conventional lithographic printing materials (PS plates), which are characterized by the use of lithographic film as an intermediate process.

Lithographic printing materials using the TB method use a special plate-making camera with a built-in image reversal mechanism such as a prism or reflective mirror to prevent the original image from being left-right reversed, from photographing to plate-making automatically. It is being said.

Such a prepress camera is not only expensive, but also has the disadvantage that the image reversal mechanism reduces image resolution.

In order to obtain a lithographic printing plate with a normal image using a plate-making camera that does not have an image reversal mechanism, as described in Japanese Patent Laid-Open No. 48-89007, it is necessary to Methods are known for performing imagewise aphoticization of documents from the side. In this specification, this exposure method is referred to as back printing.

On the other hand, lithographic printing materials using the DTR method have insufficient resistance to mechanical abrasion, resulting in the loss of hydrophobic areas that carry ink images or gradual loss of ink receptivity. It has the disadvantage of reducing printing force. Hydrophilic areas gradually become hydrophobic due to mechanical abrasion,
As the non-image areas become smeared with ink, in the hydrophobic image areas there is a defect in uniform oily ink receptivity, which causes variations in ink receptivity in the image areas, Therefore, the area to be printed will not receive a uniform amount of ink. As with other lithographic printing plates, DTR
Even in lithographic printing materials using this method, there is a need to increase the printing durability by changing the composition of the plate material, the composition of the processing liquid, printing conditions, etc., and various improvements have been made. Special Public Service 1977-3
The same applies to the lithographic printing materials basically described in 0562.
3. Japanese Patent Publication No. 51-111103, 52-150105
, 53-9603 2 54-135002, 55-
7704, 55-100554, 56-27151
, 57-86835, and 58-196548, the printability has been significantly improved. Especially JP-A-55-10055
4, No. 58-196548, the addition of a matting agent of 2 to 10 .mu.m to the undercoat layer improves the water retention of the plate surface and significantly improves the printing durability.

However, when using an undercoat layer containing such a matting agent and applying an antihalation agent at a normal concentration to the undercoat layer in order to obtain high reproducibility of fine lines and printing durability in glazing, This caused a softening of the photographic characteristics. DT
In planographic printing materials using the R method, softening of photographic characteristics causes a decrease in printing durability of fine lines, which is contrary to the original purpose. Therefore, there is a need for a lithographic printing material using the IJTR method for back printing that has high printing durability for fine lines.

(C) Object of the Invention The object of the present invention is to provide a lithographic printing material using the DTR method for back printing, which has excellent fine line reproducibility, high contrast photographic characteristics, and high printing durability.

(Dl Structure of the Invention The object of the present invention is to provide an undercoat layer on a support in order) - In a lithographic printing material that can be backprinted and has at least a silver halide emulsion layer and a physical development nucleus layer, the undercoat layer 0.1-0.5
A no-rage anti-wear agent and an average particle size of 2 to give a transmission density of
This was achieved using a lithographic printing material for overlaying, which is characterized by containing a matting agent of ~10 μm.

Normally, when exposure is performed from the front (emulsion layer side), the causes of decreased fine line reproducibility include light reflection due to the support, light scattering by the silver halogenide grains in the emulsion layer, and It is known that irradiation is caused by

DT for full irradiation of anti-irradiation dyes or pigments
The application of the R method to lithographic printing materials was disclosed in Japanese Unexamined Patent Publication No. 4
8-89007, but 2 to 10 layers are added to 9 layers of undercoat.
In a lithographic printing material using a DTR method with high printing durability and high water retention using a μ matting agent, good printing durability of fine lines cannot be obtained.

There are known methods for adding antihalation agents to the undercoat layer and to the backcoat layer, but in the lithographic printing material using the DTR method for back printing with high printing durability and high water retention described here, The effect of preventing halation in the back coating layer was small, and only the prevention of halation in the undercoat υ layer was effective.

Furthermore, when exposure is performed from the normal front side (emulsion layer side), the higher the optical density of the antihalation layer and the greater the absorption of reflected light from the support, the better the fine line reproducibility will be obtained. JP-A No. 57-35854 discloses that in order to obtain a thin line DT surface image with sufficient printing durability in a lithographic printing material using the DTR method in which exposure is performed from the front side, a support (...
It is shown that it is necessary for the optical density (including the anti-resin layer) to be 0.6 or more (preferably 1.0 or more).

However, in lithographic printing materials using the DTR method for overprinting with high printing durability and high water retention, in which the undercoat layer contains a matting agent of 2 to 10 μm, such a highly concentrated antihalation undercoat layer is used. This not only lowered the photographic sensitivity during back-printing, but also significantly softened the photographic characteristics. DT
The softening of the photographic characteristics of the R printing plate reduces the printing durability of fine lines, halftone dots, etc., and when using a "pasted original",
This results in a serious defect in that "pasting marks" are recorded on the printing plate.

In addition, if a matting agent of 2 to 10 μm is not used in the undercoat be, the above-mentioned softening of the photographic properties will not occur, but in this case, the printing durability and water retention will be reduced as shown in JP-A-58-196548. The basic performance of the lithographic printing plate is significantly reduced.

Therefore, in order to obtain a high-quality lithographic printing material using the DTR method for overlaying, which has high printing durability, high water retention, high contrast photographic properties, and excellent fine line reproducibility, it is necessary to add 2 to 10 μm in the undercoat layer.
It is necessary to use a matting agent and an antihalation undercoat layer with a lower optical density to obtain good fine line reproducibility and fine line printing durability.

The optical '11k degree of the antihalation undercoat layer is 0.1~
If it is less than 0.1, sufficient fine line reproducibility and printing durability cannot be obtained, and if it is more than 0.5, the photographic characteristics become soft, causing various problems.

Optical density 0.1-0.5 is DTR to be exposed from the front
This value is significantly smaller than the density of the antihalation layer (1.0 or more) in lithographic printing materials using the method, but in the case of back printing, the support is located in front of the photosensitive layer in the optical path on the platemaking camera (original). side), the effect of light reflected on the support on fine line reproducibility is probably relatively small.

Any antihalation dye or pigment can be used in the antihalation layer, but carbon black is most preferably used. Carbon black is preferably used in an amount of 1 to 5% by weight based on the binder (preferably gelatin).

In the present invention, the matte 4J having an average particle size of 2 to 10 μm includes silica, clay, talc, Seecrite nano inorganic matting agent, rice starch, polymethyl methacrylate,
Examples include organic matting agents such as polystyrene and cellulose acetate propionate, but particularly preferred are silica particles with an average particle size of 4 to 10 μm. The amount of these matting agents used in the undercoat layer is about 5 to 40% by weight based on the hydrophilic colloid binder. 1 to 20 relative to the hydrophilic colloid binder when included in the silver halide emulsion.
It is about % by weight, and is used in a smaller amount than the matting agent used in the undercoat layer. Generally, the ratio to the hydrophilic colloid binder can be set at about 1/2 to 1/10.

The undercoat layer in the present invention uses seratin alone or in combination with gelatin and hydrophilic colloids such as those described in JP-A-55-100554, sodium alginate, cellulose derivatives, polyvinyl alcohol, and polyvinylpyrrolidone. I can do it. As the curing agent for the ceratin layer, formalin, mucochloric acid, geltaraldehyde, silicaxal, an initial condensate as described in JP-A-54-130936, active halogen type, ethylene quine type, vinyl sulfone type, epoxy type, or chromium can be used. Known substances such as salt can be used.

The support used in the lithographic printing material of the present invention is a light-transmissive support, such as a film ( cellulose acetate film, polyvinyl acetal film, polystyrene film, polypropylene film, polyethylene terephthalate film),
Composite films such as polyester, polypropylene, or polystyrene films coated with polyethylene films may be mentioned. Atsushi is optional, but 50-200j1
A range of m is preferred.

As the photosensitive silver halide emulsion layer, all known ones can be used, but preferably those made in Japanese Patent Application Laid-open No. 49-554
This is as described in 02.

The physical development nucleus layer is also JP-B No. 48-30562, JP-A No. 49-Sho.
55402, 53-21602, etc. can be used.

The weight ratio of hydrophilic colloid to silver halide, expressed as silver nitrate, is generally between 3 and 0.2, preferably 1.5.
~0.3. The amount of silver halide present on the support is from about 0.2 to about 5 g7m'', preferably from 0.5 to 3 g.
/ml silver nitrate.

As the physical development nucleus, known metals such as antimony, bismuth, cadmium, cobalt, palladium, nickel, silver, lead, zinc, and their sulfides can be used. The physical development nucleus layer does not need to contain hydrophilic colloids, and may include gelatin, carboxymethyl cellulose,
Gum arabic, sodium alkinate, hydroxyethyl starch, dextrin, hydroxyethyl cellulose,
Hydrophilic holoids such as polystyrene sulfonic acid, a copolymer of vinyl imitazole and acrylamide, and polyvinyl alcohol may also be included.

Hygroscopic substances, such as wetting agents such as sorbitol and glycerol, may be present entirely in the core layer.

Furthermore, the core layer may also contain pigments for preventing scumming, such as barium titanium sulfate dioxide, china clay and silver, and hardeners, such as formaldehyde, as well as complexing agents.

The DTI'L treatment solution used in the present invention contains alkaline substances such as sodium hydroxide, potassium hydroxide, tertiary phosphate, etc., sulfite as a preservative, 111
m-agents such as hydroxyethyl cellulose, carboxymethyl cellulose, antifoggants such as potassium bromide, 1-phenyl-5-mer captotetrazole, complexing agents such as thiosulfates, thiocyan rR salts, cyclic imides,
Examples of agents such as thiosalicylic acid are hydroquinone, 1-
Phenyl-3-pyrazolidone, p-methylphenol, etc., development modifiers, such as polyoxyalkylene compounds, onium compounds, etc. can be included.

The lithographic printing plate of the present invention is, for example,
, U.S. Pat. No. 3,721.559, can be used to convert or enhance ink receptivity. The printing method, the desensitizing liquid, the dampening liquid, etc. used can be generally well-known methods.

(Smell) Examples The present invention will be explained below with reference to examples, but of course it is not limited to these examples.

20μm polyethylene on both sides of 175jm polyester film? [1] After applying corona numerical treatment to the back side of the support and applying 9 layers of back coating, the surface of the support was subjected to corona radiation 11
After L, the amount of carbon black added was changed (Table 1,
E), silica with an average particle size of 7 μm (0,68/m')? An undercoat containing NI (Ceratin 3°58/m") and a high contrast sensitized silver chloride emulsion (Ceratin 1.08/m") on top of seven tl-silver nitrate L517m"
It was Kubobu. After heating and hardening #4, JP-A-57-8B835
The same core coating liquid as Sample J of Example 1 was applied to make a planographic impression.
It was used as a material.

The density 1.
5 wedge images, fine lines with different line widths, tint dots, and gold. To 3! Ik*L, the originals were photographed from the back side of these samples using reflected light, and the following transfer developer was used at 30"Cl2.
The image was processed for 0 seconds.

After the development process, the nuclear master plate was passed between two squeezing rollers to remove excess developer, and immediately treated with a neutralizing solution having the following composition at 25°C for 20 seconds, and the excess liquid was removed using a squeezing roller. , dried at room temperature.

Transcription f! ni'a Neutralizing solution Load the lithographic printing plate prepared by the above operations into an offset printing machine, apply the following desensitization agent to the plate surface,
Egg paulownia was carried out using the following dampening solution.

Desensitizing liquid Moisture resistant liquid Table 2 Degrees of g are shown on the l0jlXB scale.

The results are shown in Table 2.

[Dissolving power]

In the relative evaluation when sample A is considered to be good, Δ represents very poor, ×μ represents very poor.

CIlCl1t force] Evaluation was performed using a narrow edge of 5 Ua.

1... 5,000 sheets or less 2...
・・・・・・ 5,000-10,000 sheets 3・・・・・・
...10,000 sheets or more (F') Effects of the invention The present invention is a back printing lithographic printing material that can obtain left and right images using a plate making camera without an image reversal mechanism and the DTR method, and is capable of fine line reproduction. It is a lithographic printing material with excellent properties, high contrast, high printing durability, and high water retention.

Claims (1)

[Claims] In a back-baking lithographic printing plate having at least an undercoat layer, a silver halide emulsion layer and a physical development nucleus layer in this order on a support, the undercoat layer is given a transmission density of 0.1 to 0.5. A lithographic printing material for back printing, characterized in that it contains an antihalation agent and a matting agent with an average particle size of 2 to 10 μm.