JPS63141063A - Correcting material for printing plate - Google Patents

Abstract

PURPOSE:To obtain a correcting material for a printing plate capable of retarding the progress of instantaneous correcting reaction but permitting quick and secure correction by the progress of the reaction by incorporating a ferric complex salt of an org. acid and a sulfite. CONSTITUTION:A ferric complex salt of an org. acid and a sulfite are incorporated in a correcting material. Preferred example for the ferric complex salt of org. acid is ferric aminopoly-caboxylate, but ferric phosphonate is also usable. Suitable content thereof is pref. 0.1-0.5mol per one liter of the soln. of the correcting material. Usable sulfite is such as sodium sulfite, and the amt. of the sulfite to be used is pref. ca.0.2-ca.1mol. This correcting soln. can be used in the form of soln. in water, alcohol, or their mixture. Further, pref. pH of the correcting soln. is ca.6-ca.9.

Description

Detailed Description of the Invention (A> Industrial Field of Application) The present invention is directed to an offset printing plate in which a silver image is made ink receptive and unnecessary portions of the silver image formed on the printing plate are made hydrophilic. The present invention relates to an image modifying agent for offset printing plates that eliminates ink receptivity by converting the ink receptivity to color, and more specifically, it eliminates unnecessary silver images on offset printing plates formed photographically or physically. This process involves treating the surface of a part with a specific treatment agent at any stage in the printing process to completely make it hydrophilic and eliminate ink receptivity without causing any problems to the printing properties or base material. be.

Since such processing is usually called "correction" in the printing field, the present inventors will follow this term hereinafter.

Furthermore, the processing agent used in the correction operation will be referred to as a "correction agent."

(B) Prior art and its problems In general, areas that require correction that occur in printing master plates manufactured by photolithography include those that already exist in the copy original, those that occur during exposure, and other irregularities. - There are some that occur during the development process.

This means, for example, if there are unwanted images in the reproduced original, if there are dust and dirt particles, fingerprints or other stains, or if the original is made by gluing together different originals, Shadows may appear during exposure.

In order to obtain good printed matter, all of these points must be corrected during the plate-making and printing stages.

Generally speaking, correction operations are essential, and it is desirable to be able to perform necessary corrections at any stage of the plate-making and printing processes.

Many attempts have been made to correct unwanted images in offset printing plates that utilize silver images for ink receptivity.

For example, JP-A-48-92101, JP-A-51-21901
Compounds having a mercapto or thione group and a hydrophilic group described in ``Sho 54-53002, ``Sho 59-9661, etc.'' can reliably and almost instantaneously make silver images hydrophilic. However, it has drawbacks such as having a strong odor, having an adverse effect on the human body due to its strong acidity, and lacking in storage stability, so improvements are desired.

In addition, the correction agent containing red blood salt or EDTA metal salt and thiocyanate described in JP-A-48-41808 has problems with pollution, and the ink receptivity gradually decreases after printing after correction. It has drawbacks such as smudging after recovery and lack of storage stability.

In general, it is preferable for a corrective agent to respond quickly, but if the correction is completed too quickly, or if the corrective agent accidentally adheres to an undesired area, the correction should be stopped. I can't. Therefore, it would be desirable to have a modifier that causes a rapid reaction after a certain amount of time, for example, several tens of seconds.

(C) Purpose of the Invention The purpose of the present invention is to suppress the progress of an instantaneous correction reaction, to be able to return to the state before correction even if a correction error occurs, and to quickly and reliably To provide a correcting agent for offset printing plates that can be corrected and has no adverse effects on the human body or the environment.

(D) Structure of the Invention The above object of the present invention is to provide a correction agent for offset printing plates that uses a silver image as ink receptivity, which is characterized by containing at least an organic acid ferric complex salt and a sulfite. achieved by the agent.

The present invention will be explained in more detail below.

A preferred example of the organic acid ferric complex salt is an aminopolycarboxylic acid ferric salt, but a phosphonic acid ferric salt can also be used.

Organic acid ferric complex salts are usually used in the form of complex salts, but ferric salts such as ferric sulfate, ferric chloride, ferric nitrate, ferric ammonium sulfate, and ferric phosphate A ferric ion complex salt may be formed in a solution using diiron or the like and an organic acid.

7-Minopolycarboxylic acid second complex salt is a complex of ferric ion and aminopolycarboxylic acid or a salt thereof.

Typical examples of aminopolycarboxylic acids and their salts include ethylenediaminetetraic acid Iff (EDTA), EDT
A disodium salt, EDTA diammonium salt, EDT
A tetra(trimethylammonium) salt, EDTA tetrapotassium salt, EDTA tetrasodium salt, EDTA
trisodium salt, diethylenetriaminepentaacetic acid,
diethylenetriaminepentaacetic acid pentasodium salt,
Ethylenediamine-N-(β-oxyethyl)-N,N
-1N"-triacetic acid, ethylenediamine-N-(β-oxyethyl)-NSN", N-monotriacetic acid triammonium salt, propylenediaminetetraacetic acid, propylenediaminetetraacetic acid disodium salt, nitrilotriacetic acid, nitrilotriacetic acid triacetate Examples include sodium salt, cyclohexanediaminetetraacetic acid, cyclohexanediaminetetraacetic acid disodium salt, iminodiacetic acid, dihydroxyethylglycine, ethyl etherdiaminetetraacetic acid, ethylenediaminetetrapropionic acid, and the like.

Typical examples of phosphonic acids or salts thereof include diethylenetriaminepentamethylenephosphonic acid, cyclohexanediaminetetramethylenephosphonic acid, triethylenetetraminehexamethylenephosphonic acid, glycol ether diamine tetramethylenephosphonic acid, and 1,2-diaminopropane. Tetramethylenephosphonic acid, methyliminodimethylenephosphonic acid, 1,3-diaminopropane-2
-All-tetramethylenephosphonic acid, ethylenediaminetetramethylenephosphonic acid, and the like.

Organic acid ferric complex salts of any combination of these organic acids and the above-mentioned ferric salts can be used.

Organic acid ferric complex salts are used to oxidize silver images used for ink receptivity, and generally oxidize silver images to which mercapto compounds, etc., which are used to enhance lipophilicity, are strongly adsorbed. It is best to use relatively large amounts. Generally 0.05 to 1.0 per 111 parts of corrector solution
mol, preferably in the range of 0°1 to 0.5 mol, 2
More than one species may be combined.

Since the correction is not completed when the silver image is oxidized by the organic acid ferric complex salt, it is necessary to change the silver ion to a hydrophilic compound using a compound that reacts with the silver ion, or
Needs to be removed. Examples of compounds that react with this silver ion include silver halide solvents such as thiosulfate and thiocyanate, potassium bromide, sodium bromide, ammonium bromide, potassium iodide, sodium iodide, and ammonium iodide. Water-soluble halides are mentioned.

Particularly preferred are halides such as those described above, preferably about 0.3 mole or more, preferably about 0.0 mole or more per fl of corrector solution.
．． The amount is up to 5 mol or more and can be dissolved.

Two or more types may be combined.

Examples of the sulfite used in the present invention include sodium 5A acid, potassium sulfite, and sodium hydrogen sulfite. It is thought that these sulfites control the oxidation effect of the organic acid ferric complex salt in a manner convenient for the purpose of the present invention, but it is not certain.

The amount of sulfite is from about 0.1 to about 1.0 per 11 parts of corrector solution.
5 moles, preferably in the range of about 0.2 to about 1 mole.

The correction fluid of the present invention can be used as a correction fluid using water, various alcohols, or a mixed solvent thereof.

It is also possible to use a so-called correction pen method.

The pH of the correction fluid is preferably in the range of about 6 to about 9.

It can also contain elements for making the liquid viscous, such as carboxymethyl cellulose, polyvinyl alcohol, and glycerin, and elements for coloring the liquid, such as dyes and organic or inorganic pigments.

In addition, fine particle powders such as those described in JP-A No. 51-21901 may also be included.

The modifiers of the present invention are stable and odorless. In addition, corrections can be made quickly and completely, and ink will not get on the correction area even if it is rubbed strongly after correction.

Therefore, more printing can be performed.

Offset printing plates using the silver image of the present invention as ink receptivity include Japanese Patent Publication No. 48-30562, Japanese Patent Application Laid-Open No. 53-21602, U.S. Patent No. 3゜721.559@,
In addition to U.S. Patent No. 3,490,905@, etc., U.S. Patent No. 3,4
54,398 and Japanese Patent Application Laid-Open No. 53-9603, offset printing plates having silver halide images that are ink receptive are included.

(E) Examples Example 1 The same as described in Example 1 of JP-A-53-21602 except that 1.0 g/m of hydroquinone was added to the physical development nucleus layer of the offset printing plate (plate Nα3). A lithographic printing material was prepared.

After the lithographic printing material was imagewise exposed, it was immersed in a transfer developer having the following formulation at 30°C for 30 seconds to perform transfer development, and subsequently immersed in a stop solution having the following formulation for 30 seconds (25°C). The excess liquid was removed by squeezing and the material was dried under atmospheric conditions.

A correction solution was prepared using the compounds and amounts shown in Table 1 below as a correction agent, and the portions of the lithographic printing plate to be corrected were wiped with the correction solution soaked in absorbent cotton. After wiping, the area was left for the time shown in Table 2, and then the correction fluid was blotted with absorbent cotton.

[Transfer developer]

[Stopping liquid] The printing plate thus obtained was processed using an offset printing machine NieB Dick 350CD (A, B, Dick350C
D (trade name) was attached, and printing was performed after wiping the plate surface with a liquid called Prescription (E). The printing room was at 22° C. and 60% humidity.

(E) Table 2 shows the results of examining the ink acceptability of the revised areas in Table 1 according to the evaluation criteria below.

O: Does not accept ink at all.

Δ... Slight ink receptivity.

X: Perfect ink receptivity.

It is understood that if correction fluid B is wiped off in a short period of time, it will not lose its ink receptivity.

Example 2 Example 1 was followed except that the correction fluid of Example 1 was filled into a felt-tip pen. The results were the same as in Example 1.

Further, the correction effect was maintained with all correction liquids after printing 5,000 sheets.

Example 3 Example 2 was repeated using correction fluids C and D below. Similarly, the effect of sulfites was confirmed.

(g/100m of water) (F) Effects of the Invention The correction agent of the present invention is safe, can reduce correction errors, and is excellent in reliable correction and long-lasting effects.

Claims (1)

[Claims] (1) A correcting agent for offset printing plates that utilizes a silver image as ink receptivity, which is characterized by containing at least an organic acid ferric complex salt and a sulfite.