JPH01228898A - Deleting method for printing pattern - Google Patents

Abstract

PURPOSE:To easily and effectively delete the printing pattern of a printing plate by treating the surface of the plate formed by sequentially laminating a photosensitive layer and a silicone rubber layer in this order with treating solution containing as main ingredients specific organic solvent and organic base. CONSTITUTION:When the printing pattern of a printing plate made of a waterless lithographic printing plate made by sequentially laminating a photosensitive layer and a silicone rubber layer in this order on a support is deleted, the layers for forming the plate are peeled and removed with treating solution containing as main ingredients 50-100pts.wt. of polar solvent, 0-50pts.wt. of hydrocarbon, and 1-50pts.wt. of amine compound based on 100pts.wt. of both the solvents.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for erasing a printed pattern,
More specifically, the present invention relates to a method of destroying a printing plate made of a waterless lithographic printing plate in order to easily erase a printed pattern when disposing of the plate after use.

[Prior art] Types of lithographic printing plates can be roughly divided into PS plates, which require dampening water and have a liquid film layer formed by this dampening water as an ink repellent layer, and waterless plates, which have a silicone rubber layer as an ink repellent layer. There is a planographic printing method, and the former has widely penetrated the planographic printing field as a conventional technique in the past. On the other hand, the latter was developed as a completely new lithographic printing plate to eliminate all problems related to dampening water.
Practical proposals such as 6-80046 have been made.

By the way, the support of used lithographic printing plates is often an aluminum plate, so they are generally disposed of as waste aluminum by processing companies, but at that time, the printing patterns of the printing plates are kept secret or misused. There may be cases where it is necessary to delete information for prevention purposes. Particularly in the field of securities printing, it is essential to erase the printed pattern on a printing plate after use. By the way, when performing this work on the PS version, it can be easily carried out because the version structure is simple.

In other words, since the plate has a structure in which a lipophilic photosensitive layer patterned through exposure and development processes is laminated on an aluminum substrate whose surface has been subjected to hydrophilic treatment, the photosensitive layer is simply dissolved and peeled off using a polar solvent. By letting it fall off, the printed pattern can be easily erased. On the other hand, when this process is performed using a waterless lithographic printing plate, the silicone rubber layer present on the oleophilic photosensitive layer as an ink-repellent layer serves as a protective layer for the plate surface, preventing the penetration of highly polar organic solvents. Therefore, the printed pattern layer on the printing plate could not be easily erased. That is, the printing plate is immersed in an organic solvent for a long time, and when both the photosensitive layer and the silicone rubber layer swell, they are mechanically peeled off, or the plate surface is physically destroyed (such as by scraping with sandpaper). As a result, they had no choice but to take measures such as erasing the printed patterns.

[Problems to be Solved by the Invention] As a result of intensive studies by the present inventors in order to solve these problems, the present inventors solved the problem by treating the printing plate using a treatment liquid whose main components are a specific organic solvent and an organic base. The inventors have discovered that the printed pattern on the printing plate can be easily and reliably erased, and have arrived at the present invention.

[Means for Solving the Problems] That is, the present invention provides a method for erasing the printing pattern of a waterless lithographic printing plate formed by laminating a photosensitive layer and a silicone rubber layer in this order on a support. This method of erasing a printed pattern is characterized in that the photosensitive layer and silicone rubber layer constituting the plate are peeled off using a processing liquid containing the following components as main components.

(1) Polar solvent 50 to 100 parts by weight (2) Hydrocarbons O to 50 parts by weight (3) Amine compound 1 to 50 parts by weight per 100 parts by weight of the solid solvent used in the treatment liquid used in the present invention As the polar solvent, the following can be used alone or in combination.

Alcohols (methanol, ethanol, n-propanol, isopropanol, 3-methoxybutanol, 3
-Methyl-3-methoxybutanol, 2-methylpentanol-1, diacetone alcohol, ethylene glycol, diethylene glycol, triethylene glycol,
Polyethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, polypropylene glycol, hexylene glycol, octylene glycol, etc.

Phenols (phenol, cresol, etc.).

Ethers (dioxane, tetrahydrofuran, methyl cellosolve, ethyl cellosolve, butyl cellosolve, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol-n-butyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol-n-butyl ether, triethylene glycol dimethyl ether, Ethylene glycol diethyl ether, triethylene glycol di-n-butyl ether, tetraethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, dipropylene glycol monomethyl ether, tripropylene glycol monomethyl ether, polypropylene Glycol monomethyl ether etc.

) Ketones (acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, acetonylacetone, etc.) Among the above polar solvents, preferred are methyl cellosolve, ethyl cellosolve, ethylene glycol dimethyl ether, ethylene glycol diethyl ether,
Ethylene glycol-n-butyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol di-n-butyl ether, triethylene glycol dimethyl ether,
Examples include ethers having a molecular weight of 70 or more and a boiling point of 100° C. or more, such as triethylene glycol diethyl ether, triethylene glycol-n-butyl ether, and tetraethylene glycol diethyl ether.

As the hydrocarbons used in the treatment liquid of the present invention, the following may be used alone or in combination. For example, aliphatic hydrocarbons (hexane, heptane, “Isopar” E, GSH, M (aliphatic hydrocarbons manufactured by Esso Chemical)
Alternatively, it is preferable to use gasoline, kerosene, etc.), alicyclic hydrocarbons, aromatic hydrocarbons (toluene, xylene, etc.), or halogenated hydrocarbons (trichloroethane, trichloroethylene, etc.).

Among the above hydrocarbons, preferred ones have a molecular weight of 7
0 or more, and aliphatic, alicyclic and aromatic hydrocarbons having a boiling point of 60'C or more.

The amine compounds used in the treatment liquid of the present invention include primary, secondary, and tertiary amines such as aliphatic chain amines, aliphatic cyclic amines, aromatic amines, and heterocyclic amines, as well as monoamines, diamines, triamines, Amine compounds such as tetraamine and polyamine are used alone or in combination.

These amine compounds have good compatibility with the above-mentioned polar solvents and hydrocarbons, and exhibit a strong treatment effect even when added in a relatively small amount to the treatment liquid.

For example, ammonia, methylamine, ethylamine, dimethylamine, diethylamine, triethylamine, trimethylamine, propylamine, butylamine, amylamine, dipropylamine, dibutylamine, cyamylamine, tripropylamine, tributylamine, ethylenediamine, triethylenediamine, tetramethylenediamine, polyethylene imine, benzylamine, N,
N-diethylbenzylamine, N,N-dipropylbenzylamine, 0- or m- or p-methoxy or methylbenzylamine, N,N-di(methoxybenzyl)amine, β-phenylethylamine, ε,δ-phenyl Amylamine, γ-phenylpropylamine, cyclohexylamine, aniline, monomethylaniline, dimethylaniline, toluidine, benzidine, α or β-
Naphthylamine, 〇- or m- or p-phenylenediamine, pyrrolidine, piperidine, piperazine, morpholine, urothrobin, diazabicycloundecane,
Pyrrole, pyridine, quinoline, hydrazine, phenylhydrazine, N,N=-diphenylhydrazine, hydroxylamine, urea, semicarbazide, thiourea, tetraalkylammonium hydroxide, N-methylethanolamine, N-ethylethanolamine, n-butyl ethanolamine, N,N-dimethylethanolamine,
N,N-diethylethanolamine, N,N-moro-butylethanolamine, 3-hydroxypropylmethylamine, triethanolamine, 2-(2-aminoethyl)ethanolamine, 2-゛amino-1,3-propane Diol, 2-amino-2-hydroxyethyl-
1,3-propanediol, 4-hydroxybutylmethylamine, 3-methoxypropylamine, 3-ethoxypropylamine, 3-propoxypropylamine, 3-
Isopropenoxypropylamine, N-phenylethanolamine, 3-butoxypropylamine, 3-isobutoxypropylamine, 2-ethylhexyloxypropylamine, 2-ethoxyethylamine, 2-propoxyethylamine, 2-butoxyethylamine, 2-(aminoethoxy)ethanol, aminophenol, aminocresol, etc. are used. Among the above-mentioned amine compounds, particularly preferred ones have a molecular weight of 160 or more and a boiling point of 10.
Examples include aliphatic chain amines, aliphatic cyclic amines, and aromatic amines having a temperature of 0° C. or higher.

Next, the composition of the processing liquid used in the present invention will be explained. The amount of hydrocarbons added to the treatment liquid is in the range of 0 to 50 parts by weight, preferably 1 to 50 parts by weight, and more preferably 20 to 50 parts by weight. Also, the amount of polar solvent is the total amount of ff compared to the amount of hydrocarbons.
It is blended in a range of 100 to 50 parts by weight in 1100 parts by weight. In addition, the most of the amine compounds contained in the treatment liquid are
The amount is 1 to 50 parts by weight, more preferably 10 to 50 parts by weight per 100 parts by weight of the above solvent. As the amount of hydrocarbons decreases, the swelling of the silicone rubber layer, which is the ink repellent layer of the waterless lithographic printing plate, is suppressed, making it difficult for the processing liquid to reach the photosensitive layer below the silicone rubber layer. Therefore, it takes a long time for the processing liquid to attack the photosensitive layer and destroy or erase the printed pattern. On the other hand, if the amount of hydrocarbons is too large, the absolute amount of polar solvents and amine compounds will be insufficient, and it will take a long time for the processing liquid to attack the photosensitive layer and destroy or erase the printed pattern. .

A dye for coloring and a surfactant for improving coating properties may be added to the treatment liquid used in the present invention to the extent that the effects of the present invention are not impaired.

Next, the waterless planographic printing plate used in the present invention will be explained.

Examples of waterless planographic printing plate precursors that provide waterless planographic printing plates capable of exhibiting the effects of the present invention include JP-B No. 54-26923, JP-B No. 56-23150, JP-B No. 61-54222, and JP-B No. 59-Sho. 28479, JP-A-6
0-21050° There is a method proposed in Japanese Patent Application Laid-Open No. 60-229031. All of these waterless lithographic printing plates have a plate structure in which a support, a photosensitive layer, and an ink repellent layer are laminated in this order. Various compositions have been proposed, each having the function of photocuring, photoadhering, and photopeeling through photopolymerization, photocrosslinking, photodecomposition, etc.

Furthermore, when the printing plate is subjected to exposure and development steps and then used for printing, the photosensitive layer has sufficient resistance to common ink solvents and plate cleaning solvents. however,
The photosensitive layer swells with the processing solution proposed in the present invention containing the above-mentioned polar solvent and amine compound, so that it can be easily peeled off.

Next, the processing method of the present invention will be explained. When it becomes necessary to erase the printed pattern on the printing plate after the waterless lithographic printing plate described above has been mounted on a printing machine and printed, the processing liquid proposed in the present invention may be used. It is applied to the surface of the printing plate. The coating method and coating time are not particularly limited, and the effects of the invention can be sufficiently exerted simply by wetting the plate surface with the treatment liquid using a commonly used brush, sponge, hand roller, etc. That is, the hydrocarbons in the processing liquid swell the silicone rubber layer of the printing plate, and the polar solvent and amine compound permeate into and between layers below the photosensitive layer. Then, the layers below the photosensitive layer swell and the adhesive force between the layers is extremely reduced.

In addition, the printing pattern of the printing plate is generally determined by dyes and pigments added to the plate composition during the plate-making process to improve printout properties during exposure, and dyes attached to the printed areas of the plate used to improve plate inspection properties. However, these dyes and pigments are quickly decolored and erased by the amine compound that penetrates into the layers below the photosensitive layer along with the polar solvent.

The time required for the effect of the treatment method proposed in the present invention to appear varies depending on the type of printing plate, history (presence or absence of burning treatment, etc.), m of hydrocarbons, basicity of the amine compound, temperature, etc. - Generally, the printed pattern can be erased within about 5 to 30 seconds after application of the treatment liquid.

[Example] EXAMPLES The present invention will be explained in more detail with reference to Examples below.

Example 1 A 6 micron thick photocurable photosensitive layer having the following composition was provided on an aluminum substrate by a method similar to that described in Example 4 of Japanese Patent Publication No. 56-23150. .

(a) "Polylite" TDR-1131-R (manufactured by Dainippon Ink & Chemicals, Ltd., polyurethane resin) 50 parts by weight (b) Addition reaction product of 4 moles of glycidyl methacrylate and 1 mole of xylylene diamine 41 parts by weight (c) 4.4°-Gos(diethylamino)benzophenone 5.5 parts by weight (d) N-methylacridone 3 parts by weight (13) Basic Blue 26 0.5 parts by weight On this photocurable photosensitive layer, the following A silicone gum solution having the composition was applied and dried to form a 3 micron thick silicone rubber layer.

(a) Polydimethylsiloxane with OH groups at both ends (number average molecular weight 35.000> 100 parts by weight) (b) Ethyltriacetoxysilane 12 parts by weight (C) Dibutyltin diacetate 0.2 parts by weight (d) n-hebutane 1200 parts by weight A layer of silicone rubber with a thickness of 1
A 2 micron polyester film "Lumirror" (manufactured by Toshi) was laminated with a calendar roller to obtain a waterless lithographic printing plate precursor. This printing plate precursor was subjected to conventional exposure and development steps to form a printing plate, which was then mounted on a printing machine and subjected to lithographic printing in a conventional manner.

Because the printing was for securities such as stock certificates, after printing was completed,
It became necessary to erase the printed pattern to prevent misuse.

Therefore, a treatment solution having the following composition was applied to the plate surface. As a result, the printed pattern was rapidly bleached, the photosensitive layer and silicone rubber layer swelled, and when the printing plate was lightly cooled with a cloth, the surface of the aluminum substrate was easily exposed and the printed pattern was erased.

■ 60 parts by weight of ethyl cellosolve ■ 40 parts by weight of n-hebutane ■ 20 parts by weight of 3-isopropoxypropylamine Example 2 The following composition was prepared on an aluminum plate using the same method as Example 2 of Japanese Patent Publication No. 61-54222. A photoreleasable photosensitive layer was provided with a thickness of 2 microns.

(a) Phenol novolak resin with a degree of esterification of 44% (Sumilight Resin PR50235, manufactured by Takuhō Dures)
100 parts by weight of naphthoquinone-1,2-diazide-5-sulfonic acid ester (b) 20 parts by weight of 2,4-toluene diisocyanate (C) 0.2 parts by weight of dibutyltin dilaurate A silicone gum solution having the following composition was applied, dried and cured to provide a 2 micron thick silicone rubber layer.

(a) Polydimethylsiloxane with OH groups at both ends (fi average molecular weight 20,000> 100 parts by weight) (b) Bistris(methylethylketoxime) silane
8 parts by weight (C) 0.1 parts by weight of γ-aminopropyltriethoxysilane (d) 1200 parts by weight of n-heptane. East vI
A negative working waterless lithographic printing plate was obtained by laminating the J-manufactured sheets with a calendar roller. After exposure and development steps were carried out in a conventional manner to prepare a printing plate, a treatment liquid having the following composition was applied to the plate surface. As a result, the printed pattern was completely bleached in about 30 seconds, and when the printing plate was lightly opened with a cloth, the surface of the aluminum substrate was easily exposed and the printed pattern was erased.

■ 50 parts by weight of ethyl cellosolve ■ 30,000 parts by weight of m-cresol ■ 20 parts by weight of 3-butoxypropylamine [Effects of the Invention] Since the present invention is constructed as described above, a printing plate consisting of a waterless planographic medium and a printing plate. The printed pattern can be easily and reliably erased, and the used printing plate can be kept confidential and can be prevented from being misused.

Patent applicant: Toshi Co., Ltd.

Claims (1)

[Scope of Claims] When erasing the printing pattern of a printing plate made of a waterless planographic printing plate formed by laminating a photosensitive layer and a silicone rubber layer in this order on a support, the photosensitive layer and the silicone rubber layer constituting the printing plate are A method for erasing a printed pattern, which comprises peeling off a rubber layer using a treatment liquid containing the following components as main components. (1) 50 to 100 parts by weight of polar solvent (2) 0 to 50 parts by weight of hydrocarbons (3) 1 to 50 parts by weight of amine compound per 100 parts by weight of both of the above solvents