JPS62234993A - Treatment solution for planographic printing - Google Patents

Abstract

PURPOSE:To improve an ink deposition property and to make printing staining hard to generate, by containing at least one surfactant containing silicon. CONSTITUTION:A treatment solution for planographic printing contains at least one kind of a silicon-containing surfactant represented by formula [wherein R1 is 1-10C substituted or non-substituted alkyl, aryl, aralkyl, alkoxy or phenoxy group, R2 is a group same to R1, -H, -OH, -(OCmH2m)- or OR3 (wherein m is 2, 3 or 4, l is an integer of 1-100 and R3 is H, a 1-10C alkyl group or an acyl group) A and B are respectively same to R2 and n is 1-200]. The use amount thereof is pref. 0.001-5wt%. This treatment solution imparts not only a usual ink deposition property but also the ink deposition property after drying and standing and gives rapid ink spreadability and generates no background staining even if a large number of sheets are printed.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a processing liquid, that is, an etching liquid and a dampening solution, used for printing an electrophotographic offset master, 28th plate.

(Prior art) An electrophotographic offset master first coats a photoconductive fine powder such as zinc oxide on a support together with an electrically insulating resin, and then forms a lipophilic image on the photosensitive layer using an electrophotographic method. obtain.

There are also methods of forming a printing plate by directly forming an image on a master using a lipophilic shorthand or type, and methods of using an electrophotographic transfer method.

These are used as printing plates by converting the non-image areas from lipophilic to hydrophilic through etching treatment. In order to maintain hydrophilicity during printing, the processing liquid is usually diluted several times and used as dampening water.

Many treatment solutions have been proposed so far. If they are classified according to their main components, they can be divided into yellow blood salt type and non-yellow blood salt type.

Yellow blood salts have been used for a long time. It is unstable to heat and light, and has drawbacks such as a decrease in etching power and the formation of precipitates even with natural aging. Therefore, many proposals have been attempted to improve these drawbacks. Efforts are being made mainly to improve the etching power of non-yellow blood salts. However, they are still not enough. Furthermore, in recent years, the scope of application of printing using electrophotographic offset masters has expanded, and higher performance than ever has been required.

In other words, the non-image area should not have printing stains and the image area should have sufficient ink coverage (=good ink adhesion), and should be made hydrophilic with a lithographic printing treatment liquid immediately after plate making to prevent stains such as fingerprints. Even if you print several hours after processing, the fine lines and highlights of halftone dots will not fade and the ink will be sufficiently covered (
= good ink adhesion after being left to dry), normal prints can be obtained immediately after printing starts (= ink application is quick), scumming does not occur even when printing a large number of sheets, and it is non-staining. Even if ink accidentally adheres to the image area and causes stains, the stain can be easily removed by idling the printing machine (excellent ability to remove ink stains), and is hydrophilic even after long-term use. It must have characteristics such as the power not changing and no crystals or scum being generated.

(Problems to be Solved by the Invention) However, when etching is performed using a conventional processing liquid and drying is performed, there is a drawback that ink adhesion to the image area deteriorates. This drawback becomes even more noticeable when the plate is left for a long time (plate placement) after etching and drying.

One way to prevent this is to weaken the etching power (dilution, reduce the content of the main ingredient), but in this case, deterioration of the ink layer can be prevented, but it also causes stains in non-image areas during printing, causing background smudges on printed matter. I end up.

The present invention eliminates the above-mentioned drawbacks and provides a lithographic printing plate 1 that does not cause background stains on printed matter! +1 processing liquid is provided.

The first object of the present invention is to provide a processing liquid that has good ink receptivity under any conditions and is less likely to cause IJ stains.

A second object of the present invention is to provide a processing liquid that is quick to remove ink 4i and has excellent ability to remove ink-attached stains.

A third object of the present invention is to provide a treatment liquid whose hydrophilicity does not change over a long period of time and which is maintenance-free.

(Another Means to Solve the Problems) The above object of the present invention can be achieved by a lithographic printing processing liquid containing at least one silicon-containing surfactant, particularly a processing liquid which is used as a yellowish coloring agent. It was done.

Particularly preferably, the silicon-containing surfactant is represented by the following general formula (I).

A+5i-0→-B (I)+
n [wherein R1 represents a substituted or unsubstituted alkyl, aryl, aralkyl, alkoxy or phenoxy group having 1 to 10 carbon atoms.

Synonymous with R2uR1 Also u-H, -OH,%0CJ2J7"
3+ (however, the door represents any one or more of 2.44, j represents an integer from 1 to 100, and R3 represents H or an alkyl group or acyl group of UC1 to C10).

A and B may be the same or different, and each R
It is synonymous with 2. The number indicates 1 to 2000.

However, the repeating units +5i-o÷ may be contained in different structures. ] Although the main chain of the silicon-containing compound is shown as a straight chain, there is no problem even if it includes branching.

Examples of silicon-containing surfactants that can be used in the present invention are shown below, but the present invention is not restricted or limited thereby.

Typical examples of such compounds include the following.

■ (CB3) 3SL-0+sL (0M3) 2-0 sho (
C80)6-OH■ H(C2H5)Si-0(-8
i(C2H5)2-0+2(CH2CH2-0)1□-
OH These silicon-containing surfactants can be used alone or as a mixture, but the amount used (the total amount if mixed) is preferably 0.001 to 5% by weight, more preferably 0.01%. ~0.5% by weight.

As the main hydrophilizing agent, all conventionally known compounds such as yellow blood salt, phosphate, phytate, hexaammine cobalt salt, etc. can be used. Yellow blood salt may partially contain red blood salt produced by oxidation of yellow blood salt.

Furthermore, in addition to this, a pHlA moderating agent and 7) H buffering agent can be used in combination. They use well-known inorganic acids, organic acids and their salts alone or in combination.

For example, formic acid, acetic acid, butyric acid, valeric acid, lactic acid, tartaric acid, propionic acid, oxalic acid, malonic acid, succinic acid, glutaric acid, maleic acid, heptalic acid, citraconic acid, itaconic acid,
7 Malic acid, tricarballylic acid, dalicolic acid, propionic acid, thioglycolic acid, malic acid, citric acid, glucones, pyruvic acid, gelcholic acid, salicylic acid, adipic acid, doroacrylic acid, glyceric acid, p-) These include luenesulfonic acid, metal salts thereof, and organic amine salts.

Further, the addition of a chelating agent such as EDTA-2Nα or a reducing agent such as a sulfite is also preferred in order to maintain the hydrophilizing power and prevent precipitation, especially when the main hydrophilizing agent is yellow blood salt.

In addition, when the main agent is phytate, JP-A-60-23
It is also desirable to add a water-bathable cationic polymer and a low molecular electrolyte compound as shown in No. 099 to prevent staining.

In addition, as wetting agents and wetting agents, ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, Chryse IJ 7, gum arabic, carboxymethylcellulose, acrylic polymer, methanol, ethanol, isopropylene normal propyl alcohol, triethanolamine, etc. can be added. can.

Furthermore, preservatives such as salicylic acid, phenol, butyl phenol benzoate, sodium dehibiroacetate, and 4-inchazolon-3-one compounds can be added.

In addition, rust preventives such as sodium nitrite and dicyclohexylammonium nitrite can also be added.

When applying the lithographic printing processing liquid of the present invention to a printing plate, any etching processor conventionally used in this field may be used.

Furthermore, its characteristics can be fully utilized for Hunt 9 etching and pre-etching for the purpose of preventing stains such as fingerprints.

Furthermore, this lithographic printing processing liquid can also be used as a dampening water for offset masters and 28 plates by diluting it with water in the same way as normal processing liquids.

(Example) Examples of the present invention are shown below. However, the present invention is not limited by this.

Example 1 7 Sodium erocyanide 20.0 g Monoammonium phosphate 60.1 Diammonium citrate 30.09 Sodium sulfite
6.09BJ) TA-2 sodium
0.4g silicone surfactant (trade name: NU (Silicone L-7604゜manufactured by Nippon Unicar Co., Ltd.) 20.09 water (
Total) 1000.09 This prescription was used as an etching solution, further diluted 7 times with water to make a dampening solution, and Fujifilm EL
The master made with P-, Mark 11 system was printed with Hamada Star 800 using ELF ink (black, quick drying).
I printed it with I was able to print up to 10,000 sheets without any stains at all from the beginning of printing. Furthermore, while replenishing this etching solution, processing of 3000 plates was tested over a period of one month.

As a result, there was almost no difference in the quality of the printed matter between the first edition and the final 3000th edition, and no deterioration in hydrophilicity, ink receptivity, etc. was observed. Almost no crystals, dregs, or precipitates were observed in the etching apparatus. Furthermore, when a master that had been left indoors for two days after etching drying was similarly printed (drying test), the inking of the highlighted areas of fine lines and halftone dots was extremely good.

Comparative Example All tests were conducted in the same manner as in Example 1 except that the silicone surfactant was omitted from the formulation.

In the Mark@1j test, background stains appeared from the 1000th sheet onward. Furthermore, when we tested 3,000 plates over a period of one month while replenishing this etching solution, we found that the 2,000th plate had stains and a decrease in hydrophilicity. Dust was generated in the etching apparatus from the third day. Also, in the drying test, there was a tendency for ink to be difficult to get on some parts of the image.

Example 2 A test was carried out in the same manner as in Example 1, except that equimolar amounts of the compound shown in Example 2 were used in place of the silicone surfactant.

The results were as satisfactory as in Example 1.

(Effects of the Invention) From the above results, the processing liquid of the present invention has good ink receptivity as well as normal ink receptivity after being left to dry, has quick ink application, and can be used even when printing a large number of sheets. It is clear that scumming does not occur, and even after long-term use, the hydrophilicity remains unchanged and no crystals or scum are generated.

(2 others) -～-1

Claims (1)

[Scope of Claims] 1. A lithographic printing processing liquid containing at least one silicon-containing surfactant. 2. The lithographic printing processing liquid according to claim 1, which contains yellow blood salt as a main ingredient. 3. Silicon-containing surfactants have the general formula (I) ▲ Numerical formulas, chemical formulas, tables, etc. Represents an alkoxy or phenoxy group. R_2 has the same meaning as R_1 or -H, -OH, -(OCmH
_2_m)-_lOR_3, (where m is 2,
3 or 4, l represents an integer of 1 to 100, R_3 is H or C_1 to C_1_0,
(represents an alkyl group or acyl group). A and B may be the same or different, and each R
It is synonymous with _2. n represents 1 to 2000. However, the above repeating units ▲There are mathematical formulas, chemical formulas, tables, etc.▼ may be contained in different structures. ] The lithographic printing processing liquid according to claim 2, which is selected from the group of compounds.