JPS6323546B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a plate-making method for negative-working lithographic printing plates that do not require dampening water, and particularly to a plate-making method characterized by using a novel developer. A lithographic printing plate that does not require dampening water and has a silicone rubber layer as an ink repellent layer, and is a negative-working plate material, for example, has a silicone rubber layer provided on a light-releasable photosensitive layer provided on a support. A pre-sensitized one is proposed in Japanese Patent Application No. 156871/1983 (Japanese Patent Application Laid-open No. 80046/1983). These plate materials are usually plate-made by an exposure and development process at the same time as the PS plate, and a developer mainly using a combination of an aliphatic hydrocarbon and a polar solvent is used. A sharp image can be formed on the printing plate using such a solvent-mixed developer, but if the development speed is slow and the development operation is insufficient, a silicone rubber layer will remain in the image area, causing minute particles to form. This results in a printing plate with poor halftone reproducibility. Also,
A developing operation using such a developer has the disadvantage that it is susceptible to the influence of humidity during development. The present invention provides a developer that overcomes these drawbacks, has a high development speed, and is less affected by humidity. In the present invention, after exposure of a negative-working lithographic printing plate that does not require dampening water and consists of a photoreleasable photosensitive layer provided on a support and a silicone rubber layer thereon, (A) hydrocarbons of 20 to
97%, (B) polar solvents 2-99% and (C) water 0.1-30%
The present invention relates to a plate-making method for a negative-working lithographic printing plate that does not require dampening water and is characterized in that substantially only the silicone rubber layer in the exposed area is removed using a mixed solution consisting of %. Hydrocarbons used as a developer in the present invention include those capable of swelling silicone rubber, such as aliphatic hydrocarbons (pentane, hexane, heptane, octane, gasoline,
Kerosene, light oil, heavy oil, etc.) can be conveniently applied.
Gasoline and kerosene are routinely used in general printing work sites for the purpose of washing away ink from printing machines and printing plates, and there is no objection to using them as developing solutions. Of course, aromatic hydrocarbons (toluene, xylene, etc.) or halogenated hydrocarbons (triclene, carbon tetrachloride, etc.) can also be used. The content of hydrocarbons in the developer is 0 to 97% by weight. As polar solvents, those shown below are generally useful. Alcohols (methanol, ethanol, n-
propanol, isopropanol, 3-methoxybutanol, 3-methyl-3-methoxybutanol, diacetone alcohol, etc.). Ethers (dioxane, tetrahydrofuran, methyl cellosolve, ethyl cellosolve, butyl cellosolve, ethylene glycol diethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether,
diethylene glycol diethyl ether, diethylene glycol monobutyl ether, triethylene glycol monomethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol monomethyl ether, tetraethylene glycol dimethyl ether, tetrahydrofurfuryl alcohol, etc.). Esters (methyl acetoacetate, ethyl acetoacetate, methyl cellosolve acetate, ethyl cellosolve acetate, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl acetate, diethylene glycol monobutyl ether acetate, glycol diacetate, ethyl lactate, methyl propionate, ethyl propionate,
dimethyl malonate, diethyl malonate, dimethyl succinate, diethyl succinate, dimethyl adipate, etc.). Ketones (acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, acetonylacetone, etc.). At least one of the above polar solvents,
Preferably, it is used in % by weight. The developer of the present invention is constituted by adding 0.1 to 30% by weight, preferably 1 to 15% by weight of water to the developer solvent or mixed solution described above. Also, emulsions made with a suitable emulsifier or dyes added can also be used. The light-reflecting photosensitive layer used in the present invention is the one proposed in Japanese Patent Application No. 156871/1983. That is, the light-peeling photosensitive layer is one in which the silicone rubber layer thereon is removed by development without substantially removing the exposed portion of the photosensitive layer. Such a light-peeling photosensitive layer can be produced by crosslinking a known photo-solubilizable photosensitive compound with a polyfunctional compound, or by bonding an active group in the photo-solubilizable photosensitive compound with a monofunctional compound. It can be obtained by modifying the resin to make it poorly soluble or insoluble in a developer. The photo-solubilizable photosensitive compound mentioned here is
Quinone diazides usually used in positive PS plates, Wipon plates, photoresists, etc., such as esters of benzoquinone-1,2-diazide sulfonic acid and polyhydroxyphenyl, naphthoquinone-1,2-diazide sulfonic acid and pyrogallol acetone resin, naphthoquinone-1,
Examples include esters of 2-diazide sulfonic acid and phenol formaldehyde novolac resin, or complexes of diazo compounds with inorganic or organic acids, such as photosensitive complexes of diazodiphenylamine and phosphotungstic acid. . A method for introducing a crosslinked structure into such a photo-solubilized photosensitive compound includes a method of crosslinking reactive groups such as hydroxyl groups and amino groups of the photosensitive compound with a polyfunctional crosslinking agent. . As a crosslinking agent, polyfunctional isocyanates such as paraphenylene diisocyanate, 2,4
- or 2,6-toluene diisocyanate,
4,4-diphenylmethane diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, or adducts thereof, or polyfunctional epoxy compounds such as polyethylene glycol diglycidyl ethers, polypropylene glycol diglycidyl ethers,
Examples include bisphenol A diglycidyl ether and trimethylolpropane triglycidyl ether. These thermal curing processes must be carried out within a range that does not cause loss of photosensitivity of the photosensitive material, usually at 130°C or lower.
For this purpose, a catalyst or the like is used in combination. In addition, methods for introducing components that are poorly soluble or insoluble in a developer into a photo-solubilized photosensitive compound include similarly esterifying, amidating, or urethanizing the active group of the photosensitive compound. can be given. The compound to be reacted with the active group of the photosensitive compound may be a low-molecular compound or a relatively high-molecular compound, or a monomer may be graft-polymerized to the photosensitive compound. A particularly preferred photosensitive layer for use in the present invention is naphthoquinone-1,2-diazide-5-
It is obtained by crosslinking or modifying a partially esterified product of sulfonic acid and phenol formaldehyde novolak resin with a polyfunctional or monofunctional isocyanate. The appropriate thickness of the photosensitive layer with light stripping properties is about 0.1 to 100μ, preferably about 0.5 to 10μ.If it is too thin, defects such as pinholes will easily occur during coating, while if it is too thick, it will be disadvantageous from an economic standpoint. It is. In addition, other components may be added to the photosensitive layer for the purpose of improving coating film formation properties and adhesion to the support within a range that does not impair the effects of the present invention, or to make images visible during development or exposure. It is possible to add dyes etc. The silicone rubber layer used in the present invention is mainly composed of a linear organic polysiloxane having a molecular weight of several thousand to several hundred thousand and having the following repeating units. Here, n is an integer of 1 or more, R is an alkyl group, alkenyl group, or phenyl group having 1 to 10 carbon atoms, and preferably 60% or more of R is a methyl group. Such linear organic polysiloxanes can be made by adding organic peroxides and subjecting them to heat treatment, etc.
It is also possible to form a silicone rubber by sparsely crosslinking. A crosslinking agent is also added to the linear organopolysiloxane. Crosslinking agents used in so-called room temperature (low temperature) curing silicone rubber include acetoxysilane, ketoxime silane, alkoxysilane, aminosilane, amidosilane, etc., and are usually linear organic polysiloxanes with hydroxyl groups at the ends. When combined, they become deaceticated, oxime-free, alcohol-dealt, deamined, and deamidated silicone rubbers. Generally, a small amount of an organic tin compound or the like is further added as a catalyst to these silicone rubbers. The appropriate thickness of the silicone rubber layer is approximately 0.5 to 100μ, preferably approximately 0.5 to 10μ; if it is too thin, it may cause problems in terms of printing durability, while if it is too thick, it is economically disadvantageous. Not only is it
It becomes difficult to remove the silicone rubber layer during development, resulting in a decrease in image reproducibility. In the lithographic printing plate of the present invention, adhesion between the support and the photosensitive layer, and between the photosensitive layer and the silicone rubber layer is very important for basic plate performance such as image reproducibility and printing durability, so it is necessary to Accordingly, it is possible to provide an adhesive layer between each layer or to add an adhesion-improving component to each layer. In particular, for adhesion between the photosensitive layer and the silicone rubber layer, it is effective to provide a known silicone primer or silane coupling agent layer between the layers, or to add a silicone primer or silane coupling agent to the silicone rubber layer or photosensitive layer. . The support must be flexible enough to be set in a normal lithographic printing machine and capable of withstanding the load applied during printing. Typical examples include metal plates such as aluminum, copper, and steel, plastic films such as polyethylene terephthalate, and coated paper. It is also possible to provide a support by further applying a coating to these sheets for antihalation and other purposes. A thin protective film may also be laminated on the surface of the silicone rubber layer forming the surface of the planographic printing plate that does not require dampening water and is constructed as described above. As explained above, the lithographic printing plate that does not require dampening water and is used in the present invention is manufactured, for example, as follows. First, a composition solution to form a photosensitive layer is applied onto a support using a normal coater such as a reverse roll coater, an air knife coater, a Meyer bar coater, or a rotary coater such as a Whaler, and then dried and coated as necessary. After heat curing, if necessary, an adhesive layer is applied on the photosensitive layer in the same manner. After drying, a silicone gum solution is applied on the adhesive layer in the same manner and cured for several times at a temperature of usually 100 to 130°C. Heat treatment is performed for a minute to fully cure and form a silicone rubber layer. If necessary, cover the silicone rubber layer with a protective film using a laminator or the like. The thus produced lithographic printing plate, which does not require dampening water, is exposed to actinic light through, for example, a negative film sealed in vacuum. The light source used in this exposure process is one that generates abundant ultraviolet light, and can be a mercury lamp, a carbon arc lamp, a xenon lamp, a metal halide lamp, a fluorescent lamp, or the like. Next, when the surface of the exposed plate is rubbed with a developer pad using the developer of the present invention, only the silicone rubber layer in the exposed area is removed and becomes insoluble in the developer due to crosslinking or modification. The exposed photosensitive layer remains without substantially reducing its thickness, and the exposed surface of the photosensitive layer serves as an ink receiving area to provide a negative-working lithographic printing plate that does not require dampening water. By applying the developer of the present invention, a printing plate with stable developability, which has better reproducibility of minute halftone dots in a shorter development time than conventional ones and is significantly less affected by humidity during development, can be obtained. It will be done. The present invention will be explained in detail by giving examples below. Example 1 Comparative Example 1 (A) Chemical conversion treated aluminum plate (0.3 mm thick) manufactured by Sumitomo Metals
The following photosensitive layer composition was spin-coated onto
A photosensitive layer having a thickness of 2.6 μm was formed by heat treatment for 20 minutes. (a) Phenol novolac resin with a degree of esterification of 44% (Sumilight Resin PR 50235, naphthoquinone-1,2-diazide-5 manufactured by Sumitomo Duerens)
-Sulfonic acid ester 100 parts (b) 4,4'-diphenylmethane diisocyanate
20 parts (c) 0.2 parts of dibutyltin dilaurate (d) 2000 parts of methyl cellosolve acetate Next, a silicone rubber composition with the following composition was spin-coated on top of this, and the silicone rubber composition was cured by heating at 120°C for 2 minutes to form a silicone with a thickness of 2.2μ. A rubber layer was provided. (a) Dimethylpolysiloxane (molecular weight approx. 80,000 terminal hydroxyl group) 100 parts (b) Ethyltriacetoxysilane 5 parts (c) Dibutyltin diacetate 0.2 parts (d) γ-aminopropyltriethoxysilane 3 parts (e) Isopar E ( 1,650 copies (Etsuso Petrochemical Co., Ltd., aliphatic hydrocarbon) Negative film (150 lines, 1%
~99%) vacuum-adhered metal halide lamp
Exposure was done for 30 seconds at 2kw from a distance of 1m. Each of the exposed plates was developed using a developer shown in Table 1 to obtain a negative planographic printing plate that did not require dampening water. Table 1 shows the results regarding the time required to develop the printing plates and the halftone dot reproduction area of the printing plates obtained using these developers. In Table 1, Isopar H is an aliphatic hydrocarbon manufactured by Etsuso Petrochemical.

【table】

[Table] When using developing solutions No. 2, No. 4, No. 6, and No. 8 containing water, only the silicone rubber layer in the exposed area is removed, and in each case, the halftone dot reproduction area is 1. It was ~98% or more. As a comparative example, No. 1, which does not contain water,
When developing solutions No. 3, No. 5, and No. 7 are used, only the silicone layer in the exposed areas is removed, but the development time is long and the halftone dot reproducibility is insufficient. Furthermore, developing may not be possible during dry periods such as winter. Example 2 Comparative Example 2 A resol resin (Sumilight Resin PC-1, manufactured by Sumitomo Durez) was coated to a thickness of 2μ on an aluminum plate (manufactured by Sumitomo Light Metals) with a thickness of 0.24 mm, and cured at 180°C for 3 minutes to form a support. And so. On this support, the following photosensitive layer composition was spin-coated and cured by heating at 120° C. for 2 minutes to form a photosensitive layer having a thickness of 2.4 μm. (a) Naphthoquinone in phenolic novolac resin
1,2-diazide-5-sulfonic acid ester (from Example 1) 100 parts (b) 2,6-toluene diisocyanate 20 parts (c) Dibutyltin dilaurate 0.2 parts (d) Dioxane 2000 parts On top of this, γ -Aminopropyltriethoxysilane (manufactured by Union Carbide, “A1100” 0.5% by weight
A solution of "Isopar E" (manufactured by Etsuso) was spin-coated using a Whaler, and after leaving it for one day, a silicone rubber composition liquid having the composition below was spin-coated on top of the solution and heated at 120℃.
A silicone rubber layer of 2.1 μm was formed by heating and curing for 2 minutes. (a) Dimethylpolysiloxane (molecular weight approximately 80,000,
(terminal hydroxyl group) 100 parts (b) Vinyltrimethylethylketoxime)silane
8 parts (c) 0.2 parts of dibutyltin diacetate (d) 1800 parts of Isopar E A negative film with a 150-line halftone image that was vacuum-adhered to the printing original plate obtained as above was passed through it at a distance of 1 m using a 2 kW metal halide lamp. It was exposed for 60 seconds. The relative humidity of the atmosphere during development is 35
When the exposed plate is immersed in a conventional developer (Isopar E/ethanol = 35/65) at ~80% concentration and the surface of the plate is lightly rubbed with a developing pad, only the exposed silicone rubber layer is removed. When removed, the surface of the photosensitive layer is exposed and an image faithful to the original film is obtained. However, the relative humidity of the atmosphere during development
If it is less than 35%, the development speed will drop significantly, making it impossible to faithfully reproduce the image, resulting in poor development. Furthermore, when the humidity exceeds 80%, the development speed becomes significantly faster and the developability becomes inconsistent. However, when 3 parts of water is added to this developer, the developability is always constant without being affected by the humidity during development, and workability is improved. Also, the halftone reproduction area is 150 lines, 1% ~
A stable printing plate of 99% was always obtained.

Claims (1)

[Claims] 1 After exposure of a negative-working lithographic printing plate that does not require dampening water and consists of a photoreleasable photosensitive layer provided on a support and a silicone rubber layer thereon, (A) 20 to 97% hydrocarbons;
Negatives that do not require dampening water, characterized in that substantially only the silicone rubber layer in the exposed areas is removed using a mixed solution consisting of (B) 2 to 99% of polar solvents and (C) 0.1 to 30% of water. Plate making method for lithographic printing plates.