JPH03281345A - Method for correcting lithographic printing plate - Google Patents

Abstract

PURPOSE:To To always perform a stable correction by using a holder provided with at least one air hole as a correction pen. CONSTITUTION:A lithographic printing plate is corrected using a correction pen 1 formed by containing an oxidizing agent-containing correction agent for applying ink accepting properties to a recorded image. At this time, a holder provided with at least one air hole 3 is used as the correction pen 1.

Description

Detailed Description of the Invention (A) Industrial Application Field 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 correction method for an offset printing plate that eliminates ink receptivity by converting the ink receptivity to an image, and more specifically, it relates to an image correction method for removing an unnecessary silver image on an offset printing plate formed by a photographic or physical method. By treating the surface of the part with a correction pen containing a specific treatment agent at any stage in the printing process, it can be completely hydrophilized without causing any problems in printing characteristics, base material, etc., and improves ink receptivity. It is about eliminating. 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 due to 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 contamination, or if the original is made by gluing together various originals, the exposure Sometimes a shadow appears.

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

- Correction operations are essential in boat fishing, and it is desirable to be able to make 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-51-2190
1, No. 54-53002, No. 59-9661, etc., using a compound having a mercapto or thione group and a hydrophilic group. Also, JP-A-48
A method of using a correction agent containing a red blood salt or a metal salt of EDTA and a thiocyanate as described in No. 41,808.

Furthermore, JP-A-63-141064 and JP-A-63-11
No. 5171 proposes a method using a silver oxidizing agent, such as an organic acid ferric complex salt or an iodine solution, and a modifying agent consisting of a soluble bromide and/or a soluble bromide.

In particular, a correcting agent consisting of a silver oxidizing agent and soluble bromide and/or soluble iodide has certain advantages such as reliable erasability, the ability to place a printed plate after correction, and the ability to store a printing plate after printing. Because of its advantages, it is becoming the mainstream method for modifying lithographic printing plates that utilizes silver images for ink receptivity.

In the past, correction methods using these correction agents generally involved soaking a cotton swab or brush with the correction agent and applying it to the area to be erased, but recently, there has been a demand for erasing fine details of images and In order to meet the demand for simplicity, it is being considered as a correction pen.

However, when used as a correction pen, there are problems such as the stability of the correction fluid within the pen holder and poor erasability when many areas are corrected in succession.

(C) Object of the Invention The object of the present invention is to provide a method for correcting a lithographic printing plate that can be quickly and reliably corrected using a correction pen containing a correction agent.

(D) Structure of the Invention The object of the present invention is to provide a method for correcting a lithographic printing plate using a recorded image as an ink receptivity, which uses a correction pen containing a correction agent containing an oxidizing agent. This was achieved by providing a method for correcting a lithographic printing plate using a correction pen, characterized in that the correction pen uses a holder having at least one air hole.

The correcting agent containing an oxidizing agent of the present invention is disclosed in Japanese Patent Application Laid-Open No. 63-14106.
No. 4, JP-A No. 63-115171, it is a correcting agent consisting of a silver oxidizing agent such as an organic acid ferric complex salt or an iodine solution, and a soluble bromide and/or a soluble iodide. Preferably, a ferric acid complex salt is used as the oxidizing agent.

A preferred example of the organic acid ferric complex salt is an aminopolycarboxylic acid ferric salt, but phosphonic acid ferric salts and the like 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.

The aminopolycarboxylic 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 ethylenediaminetetraacetic acid (EDTA) EDTA disodium salt, EDTA diammonium salt, EDTA tetra(trimethylammonium) salt, EDTA tetrapotassium salt, EDTA tetrasodium salt, EDTA trisodium salt. salt, diethylenetriaminepentanitric acid, diethylenetriaminepentaacetic acid pentasodium salt, ethylenediamine-N-(β-oxyethyl)-N, N-N--
) diacetic acid, ethylenediamine-N-(β-oxyethyl)-N,N-1N'-triacetic acid triammonium salt, propylenediaminetetraacetic acid, propylenediaminetetraacetic acid disodium salt, nitrilotriacetic acid, nitrilotriacetic acid trisodium salt, cyclohexane Examples include diaminetetraacetic acid, cyclohexanediaminetetraacetic acid disodium salt, iminodiacetic acid, dihydroxyethylglycine, engineered methyl ether diaminetetraacetic acid, ethylenediaminetetraprobionic acid, and the like.

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

Any combination of these organic acids and the above-mentioned ferric salts can be used as an organic acid ferric complex salt.

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 recommended to use a relatively large amount. Generally, the amount is in the range of 0.05 to 1.0 mol, preferably 0.1 to 0.5 mol, per 11 of the modifier solution, and two or more types may be combined.

Soluble bromide, soluble iodide means bromide and iodide that are soluble in the solvent of the corrector solution.

Usually, water is used as part or all of the solvent, so
Specific examples include water-soluble bromides or iodides such as potassium bromide, sodium bromide, ammonium bromide, potassium iodide, sodium iodide, and ammonium iodide.

It is thought that these bromides and iodides react with the silver image (which has become silver ions) oxidized with an organic acid ferric complex salt, change into silver halide, and become hydrophilic.

The amount of soluble bromide or soluble iodide is 0.000% per 11 parts of corrector solution. 3 mol or more is required, preferably 0
．． The amount is up to 5 mol or more and can be dissolved. Two or more types may be combined.

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

The concentration of the modifier ranges from about 5 to about 50%, preferably from about 10 to about 40% by weight of the organic acid ferric complex salt and soluble bromide and/or iodide.

In addition, elements that make the liquid viscous, such as carboxymethyl cellulose, polyvinyl alcohol, and glycerin, and elements that color the liquid, such as dyes and organic or inorganic pigments, can be included, but these are essential elements. isn't it.

A typical pen used in the present invention is a so-called felt-tip pen, which has a structure that allows correction fluid to be filled into the container of the pen, and the pen tip separates the image area and non-image area during processing. It is preferable to have a hardness that does not cause scratches on the parts, and to have at least one air hole 3 in the position shown in FIGS. 1.2 and 3. The size of the air hole 3 depends on the size of the pen tip 2 and the viscosity of the liquid, but a diameter of 0.1 to 2.511I11 is good.
Preferably, the diameter is 0. -2 to 1.0 days is good.

The position of the air hole 3 is preferably close to the pen tip 2, but may also be positioned as shown in FIG. The number of air holes 3 depends on the size of the air holes 3, but one is sufficient if the diameter is about 1 square inch, but there may be more than one.

The air hole 3 improves the flow of the correction fluid from the correction pen 1 so that correction fluid close to new fluid is always supplied to the tip of the pen 2. By keeping the oxidizing power of the oxidizing agent constant or by oxidizing the silver image, trivalent EDTA iron salt becomes divalent EDTA iron salt without oxidizing ability (in other words, the silver image cannot be corrected). , this divalent EDTA iron salt is converted into trivalent EDTA
Due to the restoring action of the iron salt, it is thought that the correction properties of the correction pen 1 containing the correction agent containing the oxidizing agent are stabilized.

According to the correction method using the correction pen 1 of the present invention, quick
Corrections can be made reliably, and ink will not get on the correction part when placing a printing plate after correction or placing a printing plate after printing.

Offset printing plates that use the silver image of the present invention as ink receptivity include Japanese Patent Publication No. 30562/1982, Japanese Patent Application Laid-open No. 21602/1983, and U.S. Pat. No. 3.721.559.
In addition to U.S. Patent No. 3,490,905, etc., U.S. Patent No. 3.4
54.398, JP-A-53-9603, and other offset printing plates having silver halide images that are ink receptive are included.

(E) Examples Example 1 Hydroquinone 1. A lithographic printing material was produced in the same manner except that the content was 0 g/rri.

After imagewise exposing the lithographic printing material, it was immersed in a transfer developer having the following formulation at 30°C for 30 seconds to effect the transfer phenomenon, 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.

As a correction pen, a correction liquid prepared using the compounds and amounts shown in Table 1 below was injected into the type with air holes shown in Figure 1.2.3 and into a holder without air holes for comparison, and the following conditions were applied. Then, the portions of the lithographic printing plate to be corrected were wiped with a correction pen.

Condition A: 0.5cm
Correct the 5cm silver image area.

Condition B: 5aI+×5al after using as a correction pen and aging.
Immediately after retouching the silver image area of 0.5cm x 0°5an, the silver image area of 0.5cm x 0°5an is retouched.

Condition C: After opening the pen corrected under Condition B and leaving it for one hour, the silver image area of 0.5anXO and 5an is corrected.

[Transfer developer solution [Stop solution] The printing plate thus obtained was processed using an offset printing machine N.B. Dick 350CD (A, B, Dick 3
50CD (trade name), and printing was performed after wiping the plate surface with a liquid called Prescription (E). The printing room is 22℃ and humidity 60%.
Met.

[Eco] The ink receptivity (background smearing) of the corrected areas on the 20th and 2,000th printing was evaluated, and the results are shown in Table 2.

Table 2 Corrected Evaluation ○... Not accepting ink at all △... Slightly ink accepting ×... Completely accepting ink Example 1 was repeated except for changing to KBr,
Similar results as in Example 1 were obtained.

Example 3 Example 1 was repeated, except that the size of the air hole of the modified pen of Example 1 was as shown in Table 3 below, and similar results were obtained.

Table 3 (F) Effects of the Invention The correction method using the correction pen of the present invention allows corrections to be made quickly and reliably, and the action of the air holes in the holder allows stable corrections at all times.

[Brief explanation of drawings]

1 to 3 are side views of a correction pen used in the present invention. 1. Correction pen, 2. Pen tip, 3. Air hole.

Claims (1)

[Claims] 1. In a method of correcting a lithographic printing plate using a silver image as an ink receptivity, the method uses a correction pen containing a correction agent containing an oxidizing agent, and the correction pen has at least one air hole. A method for correcting a lithographic printing plate using a correction pen, the method comprising using a holder having a correction pen.