JPH0428294B2 - - Google Patents

Description

[Detailed description of the invention]

[Technical Field] The present invention relates to a lithographic printing plate that does not require dampening water and is formed by coating a specific photosensitive layer and a silicone rubber layer on a support. [Prior art] In planographic printing using the conventional offset method, the composition of the dampening water, the amount supplied, and the balance of the ink have a large effect on the printing results, so very advanced techniques are required for supplying the dampening water. ing. For this reason, the industry that specializes in offset printing has long awaited the emergence of a lithographic printing plate that does not require dampening water. In recent years, many proposals have been made regarding lithographic printing plates that do not require dampening water to meet this requirement. Among them, a lithographic printing plate that does not require dampening water and uses a novolac resin naphthoquinone-1,2-diazide-5-sulfonic acid ester was developed in JP-A-55-1999.
It is disclosed in Japanese Patent Application Laid-open No. 59466 and Japanese Patent Application Laid-open No. 110249/1983. These methods involve rubbing the surface with a brush, cloth, sponge, etc. impregnated with a solvent that penetrates the silicone rubber layer and dissolves only the exposed areas, thereby dissolving the photosensitive layer in the exposed areas and peeling off the upper silicone rubber layer. It is developed with However, there were drawbacks that the developing speed was not sufficient and there was variation in the developing speed. In particular, when stored in a dry atmosphere, the development speed is significantly reduced, so that it is very difficult to control the development conditions. [Object of the Invention] An object of the present invention is to provide a lithographic printing plate that does not require dampening water and whose development speed is not affected by the storage atmosphere and whose development conditions can be easily controlled. [Configuration of the Invention] The configuration of the present invention is a lithographic printing plate that does not require dampening water and is formed by coating a photosensitive layer and a silicone rubber layer on a support in this order, and the photosensitive layer is made of naphthoquinone-1,2-
The esterification rate with diazide-5 or 4-sulfonic acid is 35% or more, and the esterification rate with a monovalent organic acid having 1 to 20 carbon atoms without active hydrogen is 30% or more.
This is a lithographic printing plate that does not require dampening water and is characterized by being made of a photosensitive novolak resin having a total esterification rate of 65% and a total esterification rate of 65 to 100%. As the photosensitive layer, naphthoquinone as mentioned above is used.
A modified phenol or cresol novolac resin introduced by 1,2-diazide-5 or 4-sulfonic acid and an organic acid ester bond is used. It is necessary that the esterification rate with naphthoquinone-1,2-diazide-5 or 4-sulfonic acid is 35% or more. When it is less than 35%, it is difficult to see a difference in solubility in the developing solvent between exposed and unexposed areas. Any esterification rate of 35% or more can be used depending on the required performance such as sensitivity, developability, image reproducibility, etc. However, due to steric hindrance, it is difficult to react the hydroxyl groups of most novolak resins. It is difficult and economically disadvantageous. Therefore, the purpose of the present invention can be achieved by setting the esterification rate of naphthoquinone-1,2-diazide-5 or 4-sulfonic acid to the required performance and esterifying the remaining hydroxyl groups with an organic acid. can. As the organic acid, a monovalent organic acid having 1 to 20 carbon atoms and having no active hydrogen that reacts with the ketene compound produced by exposure to light is used for esterification. The esterification rate at this time needs to be 30 to 65% in order to achieve a sufficiently high development speed, which is the objective of the present invention, and to prevent variations in the speed. Further, the total esterification rate of the novolac resin must be 65 to 100%. The photosensitive novolac resin used in the present invention is
Although there are various synthesis methods, it can be easily obtained by conventionally known general methods. For example, naphthoquinone-1,2-diazide-5 or 4-sulfonic acid halide and organic acid halide are dissolved in an organic solvent together with a novolac resin, and an aqueous alkali solution such as sodium carbonate or a solution of a tertiary amine in an organic solvent such as pyridine is added dropwise. can be synthesized by Other synthetic examples include organic acid derivatives, such as acid anhydrides, which react with the hydroxyl group of novolak resin to form an ester bond, similar to organic acid halides.
After reacting isocyanate or the like with a novolak resin in an organic solvent in the presence of a catalyst such as a tertiary amine, naphthoquinone-1,2-diazide 5 or 4 is added.
- A method in which a sulfonic acid halide is dissolved and an aqueous alkali solution such as sodium carbonate or a solution of a tertiary amine in an organic solvent such as pyridine is added dropwise to the solution, or, in the opposite direction, naphthoquinone-1,2 is added to a novolac resin. -Diazide There is a synthesis method in which 5- or 4-sulfonic acid halide is reacted and then acid anhydride, isocyanate, etc. are reacted. Next, specific examples of organic acid derivatives without active hydrogen that can be used in the present invention will be shown.

【formula】

[Formula] RSO ₂ X,

[Formula] (n=0, 1 or 2) etc. organic acid halide

【formula】

Acid hydrides such as [Formula], etc. [R is an alkyl group having 1 to 20 carbon atoms, an aralkyl group, a cycloalkyl group, or a cycloalkyl group having 6 to 6 carbon atoms]
20 phenyl groups and naphthyl groups, which may be substituted with organic groups that do not contain active hydrogen (active hydrogen here means hydrogen that reacts with ketene compounds generated by exposure, alcohol,
Phenol, OH group of enol, mercaptan
It is a hydrogen attached to a functional group such as the SH group or the NH group of an amine). Further, in the case of a compound containing two or more R's, the R's may be the same or different. X is a halogen atom such as Cl or Br. ] The photosensitive resin of the present invention synthesized as described above is preferably applied as a photosensitive layer to a thickness of 0.5 to 5 μm. If it is too thin, it will cause pinholes, and if it is too thick, it will be more likely to cause cracks, and it will also be economically disadvantageous. Necessary additives such as pigments, dyes, resins, plasticizers, etc. can be added to the photosensitive layer as long as they do not impair its performance. The thickness of the silicone rubber layer used as the ink repellent layer used in the present invention is preferably 0.5~
100μ, more preferably 1 to 50μ is used. A useful silicone rubber is a silicone rubber whose main component is a linear polysiloxane having the following repeating units and having a molecular weight of 4 to several hundred thousand. (R is preferably an alkyl group having 1 to 10 carbon atoms or a phenyl group, and 60% or more of R is a methyl group.) This linear organic polysiloxane is usually one having a terminal hydroxyl group, and acetoxysilane , ketooxime silane, alkoxysilane, etc., and crosslinking is performed by heat treatment in the presence of a catalyst such as an organic tin compound, and used as a silicone rubber layer. In addition, if necessary, for adhesion between the silicone rubber layer and the photosensitive layer, or between the photosensitive layer and the support,
It is also effective to provide a known silicone primer or silicone coupling agent layer between the layers, or to add a known silicone primer or silane coupling agent to the silicone rubber layer or photosensitive layer. As the support, paper, plastic film or sheet, natural or synthetic rubber sheet, metal plate, etc. are used. These supports can be further provided with a coating layer or a laminating layer for prevention of halation and other purposes, and can be used as supports. The silicone rubber layer forming the surface of the dampening water-free lithographic printing plate constructed as described above may be laminated with a protective film to prevent scratches, dust, etc. Useful protective films include polyethylene, polypropylene, polyvinyl alcohol, polyethylene terephthalate, and the like. The lithographic printing plate that does not require dampening water according to the present invention is manufactured, for example, as follows. First, a photosensitive resin solution is applied onto the support using a normal coater such as a reverse roll coater, air knife coater, Meyer bar coater, etc. or a rotary coating device such as a wheller, and after drying, a similar coating is applied on top of this photosensitive layer. Apply an adhesive layer if necessary and dry, usually at 100-120℃.
The silicone rubber layer is formed by heat treatment for several minutes at a temperature of . Furthermore, if necessary, a protective film is laminated on this silicone rubber layer using a laminator or the like. The thus-manufactured lithographic printing plate of the present invention, which does not require dampening water, is exposed to ultraviolet light by vacuum-adhering a negative film having a predetermined pattern, for example. As a light source that generates ultraviolet rays, a mercury lamp, a carbon arc lamp, a xenon lamp, a methyl halide lamp, a fluorescent lamp, etc. can be used. Next, when the surface is rubbed with a developing pad such as a cloth, brush, or sponge impregnated with a developing solution, the photosensitive layer in the exposed area is dissolved and the upper silicone rubber layer is easily peeled off, exposing the support. As a developer, it penetrates the silicone rubber layer,
A material that dissolves only the exposed photosensitive layer is used. Such developers include methanol,
Alcohols such as ethanol are preferred, but in order to more easily penetrate into the photosensitive layer, aliphatic hydrocarbons such as hexane and heptane, which can swell the silicone layer, aromatic hydrocarbons such as toluene and xylene, etc. It is also preferable to use a mixture of. EXAMPLES The present invention will be explained in more detail by way of Examples below, but the embodiments of the present invention are not limited thereto. Example 1 The esterification rate with naphthoquinone-1,2-diazide-5-sulfonic acid was 41% (measured by IR spectrum), and the esterification rate with acetic acid was 49% (IR
Total esterification rate is 90% (measured from spectrum)
phenolic novolac resin (manufactured by Sumitomo Durez,
A 15% by weight solution of Sumiresin PR-50731) in dioxane was applied to the surface of a 0.18 mm thick polyethylene terephthalate film (Toray, Lumirror) using a #12 Meyer bar coater, dried at 100°C for 4 minutes, and 2.6μ A photosensitive layer was formed. On top of this, γ-aminopropyltriethoxysilane (manufactured by UCC, A
A 2% by weight solution of Isopar E (manufactured by Etsuso) of 1100) was applied with a #3 Meyer bar coater to a set film thickness of 0.08 μm after drying, and then dried at 120° C. for 40 seconds. A 25% by weight Isopar E solution of a silicone gum composition having the following composition was applied onto this using a #16 Meyer bar coater, and then heated and cured at 100°C for 4 minutes to obtain a silicone rubber layer with a thickness of 4.8μ. Ta. (a) Polydimethylsiloxane (molecular weight approximately 80,000, terminal OH group) 100 parts by weight (b) Ethyltriacetoxysilane 5 parts by weight (c) Dibutyltin diacetate 0.2 parts by weight The printing original plate obtained as above was mixed with 20 parts by weight. °C, 60
After storage at %RH for 7 days, the film was exposed for 45 seconds from a distance of 1 m using a metal halide lamp (Idolfin 2000, manufactured by Iwasaki Electric) through a negative film with a linear image having a line width of 100 μm to 15 mm. After immersing the printing plate in a developer of Isopar E/ethanol = 40/60 for 1 minute, rubbing it with a pad (Long Run Carpet, manufactured by Kawashima Orimono) under a load of 10 g/m ² , the silicone layer in the exposed area was removed 7 times. It is removed by the number of times it is rubbed,
An image faithful to the negative film with the exposed surface of polyethylene terephthalate was obtained. Comparative Example 1 The photosensitive resin of Example 1 was replaced with naphthoquinone-1, naphthoquinone-1,
When development was performed under the same conditions as in Example 1 except that the phenol novolak resin (manufactured by Sumitomo Durez, PR-50731) with an esterification rate of 41% with 2-diazide-5-sulfonic acid was used, the exposed areas were It took 48 rubbings before the surface of the polyethylene terephthalate film was exposed to light. Example 2 The original printing plate obtained in Example 1 was heated to 29°C and 40%RH.
After storage for 7 days, the film was developed under the same conditions as in Example 1, and the surface of the polyethylene terephthalate film in the exposed area was exposed after 8 rubbings. Comparative Example 2 When the original printing plate of Comparative Example 1 was stored under the same conditions as in Example 2, exposed to light, and developed, it was found that 85 rubbings were required before the surface of the polyethylene terephthalate film in the exposed area was exposed. . Example 3 A photosensitive resin was esterified with naphthoquinone-1,2-diazide-5-sulfonic acid at a rate of 47%, and with benzoic acid at a rate of 38%, with a total esterification rate of 85%. A printing original plate was obtained using chemical conversion treated aluminum (manufactured by Sumitomo Light Metal) with a thickness of 0.23 mm as a support under the same conditions as in Example 1, except for Sumiresin PR-50235 (manufactured by Sumitomo Durez), and under the same conditions as in Example 1. The film was stored at 1000 ml, exposed to light, and developed. After 9 times of rubbing, the surface of the chemical conversion treated aluminum in the exposed area was exposed. Comparative Example 3 The photosensitive resin of Example 3 was replaced with naphthoquinone-1, naphthoquinone-1,
The resin was stored, exposed, and developed under the same conditions as in Example 3, except for using a phenol novolak resin (manufactured by Sumitomo Durez, PR-50235) having an esterification rate of 47% with 2-diazide-5-sulfonic acid. However,
By the time the surface of the chemically treated aluminum in the exposed area is exposed
A total of 71 rubs were required. Example 4 The original printing plate obtained in Example 3 was stored in a silica gel desiccator at 20°C for 7 days, exposed to light, and developed. After 10 rubbings, the surface of the chemical conversion treated aluminum in the exposed area was removed. exposed. Comparative Example 4 The original printing plate of Comparative Example 3 was stored under the same conditions as in Example 4, and exposed and developed.
A total of 116 rubs were required. Example 5 Esterification rate of photosensitive resin with naphthoquinone-1,2-diazide-5-sulfonic acid: 42%, p-
A printing original plate was obtained under the same conditions as in Example 3, except for using a phenol novolac resin (Sumitomo Durez, Sumiresin PR-50235) with a total esterification rate of 82% and an esterification rate of 40% with toluenesulfonic acid.
After storage under the same conditions, exposure and development were performed. The surface of the chemical conversion treated aluminum in the exposed area was exposed after 12 rubbings. Comparative Example 5 The photosensitive resin of Example 5 was replaced with naphthoquinone-1, naphthoquinone-1,
When development was carried out under the same conditions as in Example 5 except that the phenol novolak resin (manufactured by Sumitomo Durez, PR-50235) with an esterification rate of 42% by 2-diazide-5-sulfonic acid was used, the exposed areas were It took 70 rubbings before the surface of the chemically treated aluminum was exposed to light. Example 6 The printing original plate obtained in Example 5 was stored at 20°C and 49% RH for 7 days in the same manner as in Example 2, and then developed under the same conditions. The surface of chemically treated aluminum was exposed. Comparative Example 6 When the original printing plate of Comparative Example 5 was stored and developed under the same conditions as in Example 6, it required 94 rubbings before the surface of the chemically treated aluminum in the exposed area was exposed.

Claims (1)

[Claims] 1 A dampening water-free planographic printing plate comprising a photosensitive layer and a silicone rubber layer coated in this order on a support, the photosensitive layer comprising naphthoquinone-1,2-diazide-
Esterification rate with 5 or 4-sulfonic acid is 35
% or more, with 1 to 20 carbon atoms and no active hydrogen
The esterification rate with valuable organic acids is 30-65%,
A lithographic printing plate that does not require dampening water and is made of a photosensitive novolac resin having a total esterification rate of 65 to 100%.