JPS6215360B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a desensitizing agent that is a main component of a desensitizing liquid used in the plate-making process of lithographic printing plates. A lithographic printing plate is used for printing by taking advantage of the difference in ink receptivity between image areas and non-image areas formed on its surface. In other words, a plate is used whose surface consists of a non-printing area made of zinc, aluminum, hydrophilic polymer, etc. that is easily wetted by water, and a printing area that is easily wetted by oil. By expanding the difference in surface chemical properties between the printed area and the printed area, the ink repellency of the non-printed area and the ink receptivity of the printed area are increased. However, the non-printing areas of such planographic printing plates do not have complete ink repellency until they are wetted with water, and oil and fat components easily adhere to them. A phenomenon called "back staining" occurs. Therefore, desensitizing liquids have traditionally been used to protect non-image areas and improve water retention. This desensitizing liquid has used gum arabic having a carboxyl group and containing arabic acid, alginic acid, cellulose glycol, carboxymethyl cellulose, etc., as well as phosphoric acid, nitrate, etc. In the desensitizing liquid composed of these, the substance that greatly contributes to the desensitizing effect, that is, the desensitizing agent is gum arabic. However, since gum arabic is a natural raw material, its supply is unstable, and desensitizing liquids containing gum arabic generally spoil during storage. Desensitizing liquids that do not use gum arabic and use polyacrylic acid as a desensitizing agent are developed in Japanese Patent Publication No. 48-40003, Japanese Patent Publication No. 49-6561, and Japanese Patent Publication No. 49-1973.
-36402 and other publications, but they have not yet achieved sufficient properties such as storage stability. The purpose of the present invention is to improve such drawbacks, and to provide a desensitizing liquid that can achieve stable supply of products, improved storage stability, improved coating properties for stain prevention, improved water retention, etc. The object of the present invention is to provide a desensitizing agent for this purpose. The desensitizing agent of the present invention that achieves the above object includes at least one kind selected from unsaturated carboxylic acids,
A copolymer copolymerized with at least one compound selected from acrylic acid or methacrylic acid ester having at least one hydroxyl group, in which all or part of the carboxyl groups are neutralized with amine or ammonia. The main ingredient is salt. This desensitizing agent is made into an aqueous solution with other additives as required to prepare a desensitizing solution for lithography. The desensitizing liquid produced by the present invention has constant properties regardless of the storage period, and has excellent coating properties, so it can be applied easily and evenly, and is resistant to stains. It also shows strong resistance. Also, due to the -COOH and -OH contained in the polymer, it exhibits a strong desensitizing effect and exhibits good water retention. Examples of unsaturated carboxylic acids used in the present invention include acrylic acid, methacrylic acid, itaconic acid, fumaric acid, maleic acid, crotonic acid, vinyl acetic acid, α-ethyl acrylic acid, and angelic acid. In addition, as the acrylic ester or methacrylic ester having at least one hydroxyl group,
Hydroxyalkyl acrylates or methacrylates are preferred, such as 2-hydroxyethyl acrylate or methacrylate,
These include 2-hydroxypropyl acrylate or methacrylate, 4-hydroxybutyl acrylate or methacrylate, and hydroxypentyl acrylate. Other examples that can be used include monoesters of polyhydric alcohols such as glycene, pentaerythritol, and trimethylolpropane, and monoesters of polyoxyalkylene glycols such as diethylene glycol, dipropylene glycol, triethylene glycol, and tripropylene glycol. It is. Further, if necessary, it is preferable to use other copolymerizable ethylenically unsaturated compounds in combination with the two components to form a three-component copolymer in order to improve coating properties. Such copolymerizable ethylenically unsaturated compounds include styrene, α-methylstyrene, vinyltoluene, methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, butyl acrylate, octyl acrylate, and 2-ethylhexyl. acrylate,
3-lauryl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, octyl methacrylate, lauryl methacrylate,
Examples include acrylonitrile, methacrylonitrile, vinyl acetate, and vinyl propionate. When using these two components or when using three components, each component can be used alone or in combination of two or more. The ratio of each component used to obtain the copolymer can be selected from a wide range depending on the purpose. Generally speaking, the preferred amount of unsaturated carboxylic acid is from 5 to 95% by weight, particularly preferably from 20 to 80% by weight. The preferred amount of acrylic ester or methacrylic ester having at least one hydroxyl group is 5 to 95% by weight, particularly preferably 20% by weight.
~80% by weight. Furthermore, when using other copolymerizable ethylenically unsaturated compounds, the preferred amount of the unsaturated carboxylic acid is 10 to 90% by weight, particularly preferably 10 to 90% by weight.
It is 60% by weight. The preferred amount of acrylic ester or methacrylic ester having at least one hydroxyl group is from 10 to 90% by weight, particularly preferably from 10 to 60% by weight. In addition, the preferred amount of other copolymerizable ethylenically unsaturated compounds is 70
It is not more than 60% by weight, particularly preferably not more than 60% by weight. If the unsaturated carboxylic acid content is 5% by weight or less, the desensitizing effect will be reduced, and if it is more than 95% by weight, ink unevenness will occur in the image area. If the amount of acrylic ester or methacrylic ester having at least one hydroxyl group is 5% by weight or less, the desensitizing effect will decrease, and if it exceeds 95% by weight, the storage stability on the printing plate will decrease. Furthermore, when a copolymerizable ethylenically unsaturated compound is used, if the proportion used is 70% by weight or more, the desensitizing effect will be reduced. The copolymer used in the present invention is produced by solution polymerization, emulsion polymerization, or suspension polymerization. In this polymerization reaction, commonly used peroxides such as benzoyl peroxide and azobisisobutyronitrile, and polymerization initiators such as azo compounds are used, and for emulsion polymerization and suspension polymerization, potassium persulfate and ammonium persulfate are used. Conventional redox polymerization initiators such as sodium hydrogen sulfite and the like may be used. Furthermore, the degree of polymerization can be adjusted using a chain transfer agent such as methylcaptan, if necessary. As the solvent used when obtaining a copolymer by solution polymerization, alcohols, ketones, esters, aromatic hydrocarbons, cellosolves can be used, but alcohols, cellosolves, etc. are particularly suitable. . The molecular weight of the copolymer thus obtained is
A preferable range is about 10,000 to 150,000 when used in a desensitizing solution. The desensitizing agent of the present invention is a copolymer amine salt or ammonium salt whose solubility in water is improved by neutralizing all or part of the carboxyl groups of such a copolymer with amine or ammonium. be. For example, 0.1 to 1.0 mol, preferably 0.5 mol per mol of carboxyl group of the obtained copolymer.
Stir well while adding ~1.0 mol of alkylamine or ammonia, then add water to obtain a desensitizing solution of desired concentration. The concentration of the copolymer salt when forming a desensitizing solution using the desensitizing agent of the present invention varies depending on its molecular weight, but it is preferably used in the range of about 2% by weight to 20% by weight. Copolymers obtained by emulsion polymerization and suspension polymerization can also be treated by neutralizing some or all of the carboxyl groups.
It can be used by diluting it to a specified concentration. The desensitizing agent of the present invention is thus a copolymer salt and has good solubility in water, so the desensitizing liquid produced by this desensitizing agent is stable as an aqueous solution, and as described above. It has constant properties regardless of the storage period, and has excellent coating properties, so it can be easily and uniformly coated. A surfactant may be added to the desensitized liquid obtained in this way, if necessary. For example, nonionic or anionic surfactants such as polyoxyalkyl phenyl ether and glycols are also effective. Furthermore, water-soluble polymers such as polyvinyl alcohol, polyvinylpyrrolidone, carboxymethylcellulose, dextrin, and gum arabic can also be used alone or in combination. At that time, the preferable amount of addition is determined based on film formability, workability, etc.
It is preferably 20% by weight or less. In addition, nitrates, as long as they do not impede the effects of the present invention,
Phosphates or other metal salts can also be added, and desensitizing liquids based on general formulations can also be used.
Can be used as an additive. The desensitizing solution for lithographic plates made from the desensitizing agent of the present invention can be applied to various lithographic plates, and there are no particular restrictions on the type of photosensitive resin used. Typical photosensitive resins that can be used include photodegradable photosensitive resins such as azide-based or diazide-based resins;
These include photodimerizable photosensitive resins such as cylindrical acid polyvinyl alcohol, and photopolymerizable photosensitive resins such as acrylic. In addition, it can be applied to all planographic materials such as PS plate, flat intaglio plate, and Wipon plate. Next, the present invention will be explained in more detail with reference to Examples. Synthesis Examples 1 and 2 500 g of isopropyl alcohol was placed in a No. 2 four-necked flask equipped with a stirrer, a reflux condenser, a dropping funnel, and a thermometer, and the flask was heated to 80° C. while purging with nitrogen gas. A mixture of 500 g of the monomer mixture shown in Table 1 and 15 g of azobisisobutyronitrile was placed in a dropping funnel, added dropwise over 2.5 hours, and then heated at 80° C. for 5.5 hours to complete the polymerization reaction. After cooling to 30°C, isopropyl alcohol is distilled and the resulting solid is vacuum-dried. Water is added to it, and 0.6 mol of triethylamine per 1 mol of carboxyl group is added to neutralize it, resulting in an aqueous solution with a concentration of 10%. did.

[Table] Synthesis Example 3 Place 1 of water in a 2 four-necked flask equipped with a stirrer, reflux condenser, dropping funnel, and thermometer.
The mixture was heated to 50°C while purging with nitrogen gas. In this, a monomer mixture with the composition shown in Table 2 is added.
200g was added and thoroughly stirred. Sufficient stirring was continued while maintaining the temperature at 50°C, and after 2 hours, a slurry-like copolymer was obtained. Further, triethylamine was added so that the degree of neutralization was 0.8, and water was added to make a 10% aqueous solution. The molecular weight of the obtained copolymer was approximately 150,000.

[Table] Synthesis Example 4 Place 1 of water in a 2 four-necked flask equipped with a stirrer, reflux condenser, dropping funnel, and thermometer.
The mixture was heated to 50°C while purging with nitrogen gas. In this, a monomer mixture with the composition shown in Table 3 is added.
200g was added and stirred for the next minute. Sufficient stirring was continued while maintaining the temperature at 50°C, and after 2 hours, a slurry-like copolymer was obtained.

[Table] Furthermore, triethylamine was added so that the degree of neutralization was 0.8, and water was added to make a 10% aqueous solution. The molecular weight of the obtained copolymer was approximately 100,000. Example 1 After degreasing a mechanically grained aluminum plate,
The surface was anodized using a sulfuric acid solution. The centerline average roughness of this plate was 0.8-1.0μ. A commercially available Wipon negative type photosensitive solution (manufactured by Western Litho Co., Ltd.) was applied onto this aluminum plate using a rotary coating machine.
This is the PS (presensitized) version. This plate was exposed to light for 45 seconds from a distance of 1 m using a 2KW ultra-high pressure mercury lamp through the image negative, and then the unexposed areas were removed using a 1% aqueous sodium carbonate solution as a developer and washed with water. Next, 0.1 part of polyoxyethylene nonyl phenyl ether (n = 6) was added to 100 parts of water to the aqueous solution obtained in Synthesis Example 1, and the mixture was stirred and used as a desensitizing solution on the plate described above. was applied using a commercially available cellulose sponge. After attaching this plate to a printing machine and wiping the surface of the plate with water in the usual manner, 10,000 copies were printed, and good quality prints were obtained with no background smudges or crushed dark areas. In addition, 1 plate after platemaking obtained by the same process was used.
When printed after several months, good printed matter was obtained without ink smearing, background smearing, dark areas being crushed, etc. Furthermore, oil and fat were forcibly attached to this plate during the storage period, but no background stains appeared during printing. Comparative Example A plate obtained in the same manner as in Example 1 was coated with an 8°
Be′ polyacrylic acid ammonium salt solution 100g and water 200g
The solution dissolved in g was applied as a desensitizing treatment liquid. After storing this plate for one month, when it was printed, ink unevenness occurred in the image area and a clear image could not be obtained. Example 2 A plate obtained in the same manner as in Example 1 was mixed with the same amount of the aqueous solution obtained in Synthesis Example 2 and a 10% aqueous solution of polyvinyl alcohol (degree of polymerization 1700, degree of saponification 80) and stirred. Add 3 parts of sodium phosphate (water)
(to 100 parts) was added as a desensitizing liquid and applied. The coating properties are good, and when I attached this plate to a printing machine and printed 10,000 copies, there was no scuffing,
A good printed matter was obtained without any collapse of dark areas. Further, the plate stored for one month as in Example 1 could also be printed without any problems. Example 3 To a plate obtained in the same manner as in Example 1, the aqueous solution obtained in Synthesis Example 3 and the same amount of 10% carboxymethyl cellulose aqueous solution were added, and in addition, nonionic surfactant polyoxyethylene nonyl fluoride was added. A mixture of 0.2 parts of enyl ether (n=9) (based on 100 parts of water) and 4 parts of magnesium nitrate (based on 100 parts of water) was mixed and stirred and applied as a desensitizing liquid. When this plate was attached to a printing press and 10,000 copies were printed, good prints were obtained with no background smudges or crushed dark areas. Also, the version I saved for a month,
Printing was possible without any problems and good printed matter was obtained. Example 4 The aqueous solution obtained in Synthesis Example 4 and the nonionic surfactant polyoxyethylene nonyl phenyl ether (n=
9) A mixture of 0.2 parts (per 100 parts of water) and 4 parts (per 100 parts of water) of sodium carbonate was mixed and stirred and applied as a desensitizing liquid. When I attached this plate to a printing machine and printed 10,000 copies, the background was smeared,
A good printed matter was obtained without any collapse of dark areas.
Furthermore, the plate that had been stored for one month could be printed without any problem, and good printed matter was obtained.

Claims (1)

[Claims] 1. A carboxyl copolymer obtained by reacting 5 to 95% by weight of an unsaturated carboxylic acid with 5 to 95% by weight of an acrylic ester or methacrylic ester having at least one hydroxyl group. A lithographic desensitizer comprising a copolymer salt in which all or some of the groups are neutralized with amine or ammonia. 2. The desensitizing agent for lithographic plates according to claim 1, wherein the unsaturated carboxylic acid is at least one of acrylic acid and methacrylic acid. 3. The desensitizing agent for nonprinting according to claim 1, wherein the acrylic ester or methacrylic ester having at least one hydroxyl group is a hydroxyalkyl acrylic ester or a methacrylic ester.