JPS6039035B2 - Processing liquid for lithographic printing plates - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a processing liquid used for a lithographic printing plate whose surface layer has a subsalt oxide monoresin dispersion system.

More specifically, the present invention relates to a desensitizing solution used when an electrophotographic recording paper in which a subsalt oxide monoresin dispersion system is coated on a base paper as a photoconductive layer is used as a master for offset lithographic EO printing. Lithographic printing in which an image is formed on an electrophotographic material having a photoconductive layer in which a photoconductive subsalt oxide is dispersed in an insulating resin such as a silicone resin or an acrylic resin by a conventional method, and then non-image areas are treated to make the non-image area fat-free. It is known to be used as a master.

Desensitizing liquids conventionally used in such treatments include desensitizing agents such as ferrocyanic compounds and phosphates, PH adjusters such as organic acids and inorganic acids, and CMC, glycerin, alginic acid, and gum arabic. It mainly contains a wetting agent such as.

However, ferrocyanide is significantly degraded by light, and this not only causes a decline in the quality of the liquid (discoloration, precipitation, etc.), but also causes so-called smudges and background stains in the non-image areas of planographic printing plates, resulting in pollution. It is recommended that its use be avoided. On the other hand, non-fattening liquids that do not contain ferrocyanide have been proposed, but they are not only more likely to cause scumming than ferrocyanide, but also result in etching marks, so these are things that should be put into practical use. .

The present invention eliminates the above-mentioned drawbacks and provides a processing liquid for lithographic printing plates that does not contain ferrocyanide and can provide clear printed matter without background stains.

That is, the present invention includes a compound obtained by reacting a methacrylic acid polymer or a copolymer of methacrylic acid and a specific monomer with a specific metal salt.

The monomer to be polymerized with methacrylic acid is represented by the following general formula. (Ta), Shi, X, :Sun, CH3, COO Sun, OC
H3, X2: day, CH3, COO day, OCH3, Y,:
Day, CH3, Y2: COO Day, COOC2 Day 5, COO
C3 days 60 days, C ratio COO days, 'C is.

C. CH3, CH2CH3, COOCH3, COOC2 days 40 days One or more of these monomers may be used.

The ratio of methacrylic acid to other monomers in the polymer or copolymer may be 100:0 (i.e., a homopolymer of methacrylic acid) to 5:99, or 0 to 70:30. preferable. The polymer or copolymer contains Mn,
A compound obtained by reacting a metal salt selected from the group of Fe, Ni, Co, Zn, Mg, and Zr is the main component of the treatment liquid of the present invention. The metal salt is preferably an organic acid salt, ie, a carboxylic acid salt, and includes salts of cobalt acetate, manganese acetate, nickel acetate, zinc acetate, magnesium acetate, iron acetate, zirconium acetate, and the like. The compound obtained by reacting the polymer or copolymer with a metal salt preferably has a metal salt-containing polymer unit of 30 mol% or less, and is contained in the lithographic printing processing liquid in an amount of 0.1 to 1% by weight. If the concentration of the reaction product is less than 0.1% by weight, the processing liquid will not have sufficient desensitizing ability, and the non-image areas of the lithographic printing plate will be prone to scumming, making it impossible to obtain printed matter with clear images. On the other hand, if the concentration of the reaction product is 10% by weight or more, the treatment liquid will have a high viscosity, which is unfavorable for handling. In addition to the reaction products described above, the treatment solution of the present invention contains PH buffers such as primary ammonium phosphate, secondary ammonium phosphate, sodium phosphate, and phosphoric acid, as well as citric acid, malonic acid, lactic acid, and tartaric acid. Various additives used in general processing liquids, such as a pH adjuster of an organic acid or an inorganic acid such as phosphoric acid or hydrochloric acid, and a hydrophilic compound such as CMC or glycerin, can be contained.

When the processing solution of the present invention is used as a desensitizing solution, it may be used at the concentration mentioned above, but when used as overflow water for a lithographic printing plate after desensitization, it is further diluted to about 2 to 10 times. can do.

As described above, since the present invention does not contain ferrocyanide, the disadvantages of ferrocyanide are eliminated, and the performance as a treatment liquid is better than that of a treatment liquid containing ferrocyanide or a treatment that does not contain ferrocyanide. It has better performance than any other liquid and is a highly practical treatment liquid.

Comparative example 1 Ferocyan soda 30
Talic acid (m) soda 309 Citric acid 10 Glycerin
10 minutes The above formulation was uniformly dissolved in 1,000 ml of water.

Comparative example 2 Ferocyan soda 20
9 Sodium phosphate 10 Ammonium talate 10 CMC
I citric acid
After 7 days, the above formulation was uniformly dissolved in 1,000 ml of water.

Comparative example 3 Chrome alum 30
Ammonium talinate 20 Ammonium talinate 30 Taglycerin
20 pm Add the above prescription to 100 ml of water.
0 Melt evenly on the desk.

Example 1 200% acetic acid Col aqueous solution was added dropwise to 500% aqueous solution of a 5% copolymer having a molar ratio of methacrylic acid/acrylic acid = 50/50%, and the mixture was reacted at 80 to 9000 for 6 hours.

After the reaction was completed, the acetic acid and the product were added dropwise to methanol in a furnace of 8U.
and make the product into a 0.5% aqueous solution. Example 2 Methacrylic acid/Hydroxyethyl acrylate = 60/40%
Mn acetate in a 50% copolymer aqueous solution with a molar ratio of 400
o. Add 400 ml of 5% aqueous solution and react at 80-9000 ml for 8 hours.

After the reaction was completed, the product obtained in the same manner as in Example 1 was made into a 1% aqueous solution. Example 3 84 g of acetic acid was added to 400 g of a 50% aqueous solution of a copolymer with a molar ratio of methacrylic acid/methyl vinyl ether = 70/30%.
．． A 3% aqueous solution was poured at 400° C., and after reaction for 8 hours at 80-9000° C., a product was obtained in the same manner as in Example 1, and then converted into a 1% aqueous solution.

Example 4 500% aqueous solution of copolymer with methacrylic acid/acrylic acid = 70/30% molar ratio 500% aqueous solution of Nil acetate 200%
' was added and reacted for 6 hours at 80 to 9000°C to obtain a product in the same manner as in Example 1, which was then made into a 1% aqueous solution.

Example 5 Acetic acid Col% in 500% aqueous copolymer solution with methacrylic acid/crotonic acid = 40/60% molar ratio
A 200% aqueous solution was added, and the mixture was reacted for 6 hours at 80 to 9,000 °C to obtain a product in the same manner as in Example 1, followed by a 1% aqueous solution.

Example 6 Methacrylic acid/crotonic acid/acrylic acid = 4
500' of 5% aqueous copolymer solution with 0/30/30 molar ratio
Add 400' of Mn acetate, 0.5% aqueous solution to
9000 for 6 hours, and the same procedure as in Example 1 was carried out to obtain a product.

The product obtained is made into a 1% aqueous solution. Ricoh Offset AP-151
The result of printing with 0 is shown.

Claims (1)

[Claims] 1. Mn, Fe, Ni, Co, Zn, Mg in a methacrylic acid polymer or a copolymer of methacrylic acid and one or more monomers represented by the following general formula. , and Z
A lithographic printing processing liquid comprising a compound reacted with one kind of metal salt selected from the group r, and wherein the metal salt-containing polymerized unit in the compound is 30 mol % or less. ▲Contains mathematical formulas, chemical formulas, tables, etc.▼