JPH0764133B2 - Cleaning agent for water transfer rerollers - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a cleaning agent that cleans and simultaneously desensitizes the surface of a water feed roller made of ceramic in lithographic printing.

In addition, in the following description, the mixing unit is a weight unit unless otherwise specified.

<Prior Art> A conventional water feed roller in lithographic printing is an iron roller that is made hydrophilic by surface plating such as chrome or copper plating.

However, the surface of this type of water feed roller is always
It is in contact with the printing plate surface on which the printing ink is placed, and because dampening water (containing phosphoric acid and other various salts) is always placed on it, it is easily corroded (corrosion makes uniform water feeding impossible. ). Therefore, the water feed roller needs to be replaced regularly.

Therefore, from the viewpoint of maintenance-free, as the water feeding roller, the one made of ceramics (at least only the surface) which is not corrosive is becoming mainstream.

Although these ceramic water feed rollers do not corrode, printing inks on the lithographic printing plate (colorants and vehicles as main components, as well as auxiliary agents made of various compounds such as surfactants) are also used. In addition, the dampening water contains various salts as described above, and the desensitizing property (hydrophilicity) of the roller surface decreases with time, and the water feeding roller surface becomes dirty ( It becomes impossible to feed water evenly, and the printed matter becomes dirty.)

Therefore, it is necessary to clean and desensitize the surface of the water feed roller every time a predetermined printing time elapses.

Conventionally, as a method of cleaning and desensitizing the surface of this water feed roller, a good solvent for printing ink, for example, a hydrocarbon-based solvent,
After cleaning the roller surface with a halogen-based organic solvent to clean it,
Desensitizing (hydrophilizing) treatment is performed by wiping the surface of the same with an aqueous solution of an inorganic acid such as phosphoric acid or the like, which is the same as that added to the fountain solution, or an inorganic salt thereof.

<Problems to be Solved by the Invention> However, in the case of the cleaning / desensitizing treatment method, the time during which printing can be continued is extremely short and the printing productivity is not good.

In view of the above, it is an object of the present invention to provide a cleaning agent for a water feed roller, which can dramatically increase the printing duration in planographic printing.

<Means for Solving the Problems> In order to solve the above problems, the present inventors have been proposed in an application relating to the same person as the applicant of the present application in the process of earnestly and striving for development. Focusing on the desensitizing treatment liquid of the plate, it was found that the desensitizing treatment liquid is also suitable as a cleaning agent for the surface of the water feed roller, and the present invention having the following constitution was conceived.

The cleaning agent for a water feeding roller of the present invention according to claim 1 is a cleaning agent used for a water feeding roller made of ceramic in lithographic printing, which is a water dispersion system in which phytic acid and dicarboxylic acid are dissolved in water. Then, the dicarboxylic acid is a combination of two or more kinds selected from the group of aliphatic saturated dicarboxylic acids having 3 to 8 carbon atoms and phthalic acid.

A cleaning agent for a water feed roller according to a second aspect of the present invention is the cleaning agent according to the first aspect, wherein the good solvent (oiliness) of the lithographic printing ink is dispersed as an oil-in-water type using an emulsifier. It is characterized by

<Detailed Description of Means> Hereinafter, each item of the means will be divided.

(1) The material of the ceramics roller to which the present invention is applied preferably contains, as a main component, an element such as zinc or aluminum in which phytic acid is easily chelated.

(2) Phytic acid, which is also known as myo-inositol hexaphosphate, binds to the surface of a ceramic roller and plays a role of increasing hydrophilicity.

That is, the phosphorus atom of phosphoric acid is coordinated (chelated) to the metal atom such as aluminum and zinc existing on the roller surface (in the ceramics) and bonded to the roller surface, and the hydroxyl group of phosphoric acid increases the hydrophilicity. It is estimated that

(3) The dicarboxylic acid is a combination of two or more selected from the group consisting of saturated dicarboxylic acids having 3 to 8 carbon atoms and phthalic acid. This dicarboxylic acid acts as an auxiliary agent of the above-mentioned phytic acid. The reason for this is presumed that these carboxylic acids also coordinate with the above-mentioned metal element and act as an auxiliary agent.

When the number of carbon atoms is less than 2, or when terephthalic acid or isophthalic acid is used, no chelating action is exhibited and the desensitizing effect is small. On the other hand, when the number of carbon atoms is 9 or more, water solubility becomes a problem, which is not desirable.

Two or more kinds of dicarboxylic acids are used in order to exert the pH stabilizing action of the detergent.

The specific names of the saturated aliphatic dicarboxylic acids are malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, and suberic acid in the order of 3 to 8 carbon atoms.

The blending amount of these dicarboxylic acids is, in molar ratio, phytic acid / dicarboxylic acid = 1 to 1.5.

(4) Especially if it is a good solvent for lithographic printing ink (oil-based),
The organic solvent is not limited, and water-insoluble hydrocarbon-based, halogenated hydrocarbon-based, and ester-based organic solvents may be appropriately selected and used alone or in combination of two or more. Usually, a hydrocarbon solvent used for washing printing inks having a boiling point range of 100 to 250 ° C. is desirable from the viewpoint of cost.

The blending amount of the solvent is 15 to 60% (desirably 20 to 40%) in the total amount of the detergent.

Specific examples of the solvent include industrial gasoline No. 4 (b.
p .: 140 to 205 ° C.), industrial gasoline (bp: 150 to 210 ° C.) and the like.

(5) As the emulsifier for emulsifying and dispersing the above solvent in the detergent, the following anionic or nonionic surfactants can be usually used.

The blending amount of this surfactant is usually related to the blending amount of the solvent, and is 0.5 to 4 parts with respect to 100 parts of the solvent.

Anionic surfactants: sodium alkylsulfate, 2-alkylnaphtholium sulfate, sodium alkylbenzenesulfonate, sodium α-olephinesulfonate, sodium N-acylamino acid, sodium alkylnaphthaleneate, N- (2
-Sulfo) ethyl-N-methylalkanamide sodium, 2-sulfosuccinic acid dialkylamide.

Nonionic surfactant: alkyl polyoxyethylene ether, alkylcarbonyloxy polyoxyethylene, p-alkylphenyl polyoxyethylene ether, NN-di (polyoxyethylene) alkane amide, fatty acid polyhydric alcohol ester, fatty acid polyhydric alcohol Polyoxyethylene, fatty acid saccharose ester.

(5) The cleaning agent for a water feed roller of the present invention, in addition to the above-mentioned compounds, may be used for preparation, and if necessary, for pH adjustment,
The addition of water-soluble alkali metal salts such as sodium hydroxide and potassium hydroxide, coloring pigments and the like does not hinder the efficacy of the present detergent.

<Operation / Effect of Invention> Since the cleaning agent for a water feed roller of the present invention contains phytic acid and dicarboxylic acid as active ingredients, each acid on the surface of the water feed roller is chelated to the metal element on the roller surface, which is good. A good bonding state can be formed, and good hydrophilicity (desensitization) of the roller surface can be maintained for a long time.

Therefore, in lithographic printing, the printing duration can be dramatically increased.

Furthermore, when both solvents of the printing ink are dispersed in the cleaning agent, oily stains on the surface of the water feeding roller are surely removed, and the above effect becomes more remarkable.

<Examples> Examples and comparative examples performed to confirm the effects of the present invention will be described below.

(1) Examples 1 to 4 and Comparative Example 1 are shown in Table 1A of Table 1, respectively.
PH of the compounded formulation shown in the column of liquid with NaOH aqueous solution (1N)
Each cleaning agent was prepared by adjusting to 4.0.

(2) Example 5 and Comparative Example 2 are the same as Example 1,
To each of the detergents prepared in Comparative Example 1, the mixed liquid shown in the liquid column of Table 1 was added with stirring to give an aqueous dispersion (oil-in-water type).
An emulsion was prepared.

(3) After wiping the surface of the ceramic water feed roller with a waste cloth soaked with each of the above-prepared cleaning agents, the lithographic printing plate below is attached to the printing machine below to start lithographic printing, and the water feed roller surface The presence or absence of dirt was visually determined every hour.

Printing plate: "FUJI PS-PLATE, FPS" (manufactured by Fuji Photo Film Co., Ltd.) is image-exposed through a mesh positive film, and then developed with a designated developing solution to form an image on the printing plate.
Prepared positive type planographic printing plate.

Printing machine: "Lithrone 25" manufactured by Komori Co., Ltd.

(4) Test results: Table 1 shows the time at which the water feed roller starts to become dirty. It can be seen that the time until the start of soiling is significantly extended compared to the case of the conventional method. In particular, the tendency is remarkable in Examples 5 to 6 in which the hydrocarbon solvent is dispersed.

Continuation of the front page (56) Reference JP 62-77994 (JP, A) JP 62-77993 (JP, A) JP 60-112495 (JP, A) JP 60-47198 (JP , A) JP 59-57793 (JP, A) JP 48-133103 (JP, A) JP 62-68793 (JP, A) JP 60-96493 (JP, A) JP 57-199694 (JP, A) JP-A-1-133795 (JP, A) JP-A-1-262193 (JP, A) Actually opened 62-116869 (JP, U) Actually opened 62-136353 (JP, U) Japanese Patent Sho 58-2839 (JP, B2)

Claims (2)

[Claims] 1. A cleaning agent used for a ceramic water feed roller in lithographic printing, which is an aqueous dispersion system in which phytic acid as a chelating agent and dicarboxylic acid as an auxiliary agent are dissolved in water. The dicarboxylic acid is a combination of two or more selected from the group consisting of an aliphatic saturated dicarboxylic acid having 3 to 8 carbon atoms and a phthalic acid, wherein the cleaning agent for a water feed roller is characterized. 2. A cleaning agent for a water feed roller according to claim 1, wherein a good solvent for the lithographic printing ink (oil) is dispersed as an oil-in-water type using an emulsifier. .