JP2016036942A - Printing plate cleaning agent for lithographic printing plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cleaning agent for lithographic printing plate having excellent ability of cleaning and removing an oily ink or a high sensitivity UV ink on a printing plate without corrosion and dissolution of a streak part of the plate or a cleaning agent having desensitization effect of a non-streak part of the plate and safety on working environment.SOLUTION: There is provided a cleaning agent for lithographic printing plate containing at least one kind of esters described in following (a) and (b). (a) Monoester of diol or an isomer of such monoester having a primary alcoholic hydroxyl group and a secondary alcohol hydroxyl group in a molecule where hydrogen binding carbon may be substituted. (b) Diester of diol or an isomer of such diester having a primary alcoholic hydroxyl group and a secondary alcohol hydroxyl group in a molecule where hydrogen binding carbon may be substituted. Pentane diol where hydrogen binding carbon may be substituted is preferably used as the diol.SELECTED DRAWING: None

Description

  The present invention relates to a cleaning agent used for cleaning a lithographic printing machine, particularly suitable for cleaning a plate surface of a lithographic printing plate.

  The offset printing method using a lithographic printing plate is a printing method that uses the property that water and oil-based ink do not mix, and the printing plate receives water and repels the ink (non-image area). And a portion (image portion) that repels water and accepts ink.

  Water containing a surfactant, a solvent called dampening water, and salts is supplied to the printing plate so that the non-image area retains water and repels ink.

  If ink residue, dust, dust, or the like adheres to the printing plate during printing, the ink adheres to that portion, leading to soiling of the printed matter. In such a case, the plate surface cleaning agent is used to remove the portion where ink residue, dust or the like is attached.

  Also, if the printing machine is stopped during a break, etc., the non-image area will dry during that time, and when printing is started again, the non-image area will not have sufficient water retention, causing ink to adhere, There are cases that lead to In order to prevent such troubles, after stopping the machine, the plate surface is quickly wiped with a plate cleaning agent to maintain the property that the non-image area does not attract oil (desensitizing effect). .

  In addition, even if the non-image area of the plate wears during printing and ink adheres to the worn portion and the printed matter becomes soiled, a certain degree of water retention is restored by washing with the plate surface cleaner. It is possible to make the printed matter less likely to get dirty.

In recent years, in offset printing, ink that is cured using a metal halide ozoneless lamp or an LED-UV lamp, so-called high-sensitivity UV ink, is becoming mainstream. Resins, monomers, etc. contained in this high-sensitivity UV ink have a polar molecular structure and are therefore difficult to dissolve in non-polar petroleum hydrocarbons (naphthenic solvents) that are components of conventional plate surface cleaning agents. . In addition, chlorinated solvents and aromatic hydrocarbons have a high detergency, but there are concerns about adverse health effects on the human body.
Further, when a solvent or chemical substance having a high detergency is used, the image area of the plate is dissolved and eroded and may drop or decrease, resulting in defects such as blurring of characters and patterns.

Patent Document 1 describes a plate surface cleaning agent containing phytic acid or a water-soluble salt thereof and other components.
Patent Document 2 describes a plate surface cleaning agent containing an aliphatic carboxylic acid ester, and examples thereof include methyl esters and ethyl esters such as palmitic acid and stearic acid.
Patent Document 3 describes a plate surface cleaning agent containing an aliphatic carboxylic acid ester, and examples include octyl such as acetic acid, propionic acid, and butyric acid, 2-ethylhexyl, capryl ester, and the like.
Patent Document 4 describes a plate surface cleaner containing a straight chain unsaturated fatty acid having 16 to 24 carbon atoms, and examples include palmitooleic acid, oleic acid, linoleic acid, arachidonic acid and the like.
Patent Document 5 describes a plate surface cleaning agent containing an isoparaffin-based hydrocarbon solvent (such as IP solvent 2028) and a specific phosphonium compound (such as methoxymethyltriphenylphosphonium chloride).
When using a plate surface cleaning agent containing fatty acids, fatty acid esters, paraffinic hydrocarbons, naphthenic hydrocarbons, etc., exemplified in these patent documents, the above-mentioned high-sensitivity UV ink tends not to be sufficiently cleaned. There is.

  There is a demand for a cleaning agent that is highly safe in the working environment and has good cleaning properties even with high-sensitivity UV inks and oil-based inks.

JP-A-61-261095 JP 2000-098629 A JP 2000-221696 A JP 2008-080635 A JP2013-052542A

  The present invention provides a plate surface cleaning agent for a lithographic printing plate that has an excellent ability to clean and remove oil-based ink and high-sensitivity UV ink on a plate surface and that does not erode or dissolve the image area of the plate. Is an issue. Another object of the present invention is to provide a cleaning agent that has a desensitizing effect on the non-image area of the plate and is highly safe in the working environment.

  In order to achieve the above-mentioned problems, the inventors have conducted research on compounds that are free from the disadvantages of conventional lithographic printing plate surface cleaner components and that are environmentally safe and suitable as components for plate surface cleaning agents. It has been found that the above-mentioned problems can be solved by containing an ester of the diol compound as a component.

(1) The present invention is a lithographic printing plate surface washing agent containing at least one of the esters described in (a) and (b) below.
(A) A monoester of a diol which has a primary alcoholic hydroxyl group and a secondary alcoholic hydroxyl group in the molecule, and hydrogen bonded to carbon may be substituted, or an isomer of the monoester.
(B) Diester of diol which has a primary alcoholic hydroxyl group and a secondary alcoholic hydroxyl group in the molecule, and hydrogen bonded to carbon may be substituted, or an isomer of the diester.
(2) Moreover, this invention is a plate surface cleaning agent for lithographic printing plates as described in said (1) in which said diol has the structure as described in the following (c).
(C) The two carbons to which the hydroxyl group is bonded are both bonded to the same carbon, and the center carbon of these three carbons is not bonded to a hydrogen atom.
(3) Moreover, this invention is a plate surface washing | cleaning agent for lithographic printing plates as described in said (1) whose total carbon number of said diol is 6-9.
(4) Moreover, this invention is a plate surface washing | cleaning agent for lithographic printing plates as described in said (3) whose said diol is the pentanediol which the hydrogen couple | bonded with carbon may be substituted.
(5) Moreover, this invention is a plate surface washing | cleaning agent for lithographic printing plates as described in said (1) whose acid component of said ester is a C12 or less total fatty acid.
(6) Moreover, this invention is a plate surface washing | cleaning agent for lithographic printing plates as described in said (5) whose acid component of the said ester is butanoic acid.
(7) Moreover, this invention is a plate surface washing | cleaning agent for lithographic printing plates as described in said (6) whose said butanoic acid is isobutanoic acid.
(8) In the present invention, the compound (a) is 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate or an isomer thereof, and the compound (b) is The plate surface cleaning agent for a lithographic printing plate as described in (1) above, which is 2,2,4-trimethyl-1,3-pentanediol diisobutyrate or an isomer thereof.
(9) Moreover, this invention is a plate surface washing | cleaning agent for lithographic printing plates as described in said (1) containing phosphoric acid and / or the salt of phosphoric acid.
(10) The present invention also provides the plate surface cleaning agent for a lithographic printing plate as described in (9) above, which contains gum arabic.

  The plate surface cleaning agent for a lithographic printing plate of the present invention has an excellent ability to clean and remove oil-based ink and high-sensitivity UV ink on the plate surface, and does not erode or dissolve the image area of the plate. In addition, it has a desensitizing effect on the non-image area of the plate and is a highly safe cleaning agent in the working environment.

The best mode for carrying out the present invention will be described in detail below. In the present specification,% or part is based on mass unless otherwise specified.
In the present specification, the plate surface cleaning agent for lithographic printing plates is also referred to as a plate surface cleaning agent.

The plate surface cleaning agent of the present invention contains at least one of the esters described in the following (a) and (b).
(A) A monoester of a diol which has a primary alcoholic hydroxyl group and a secondary alcoholic hydroxyl group in the molecule, and hydrogen bonded to carbon may be substituted, and an isomer of the monoester.
(B) Diester of diol which has a primary alcoholic hydroxyl group and a secondary alcoholic hydroxyl group in the molecule, and hydrogen bonded to carbon may be substituted, and an isomer of the diester.
The total content of the compounds (a) and (b) in the plate surface cleaning agent is preferably 1 to 60%. More preferably, it is 10 to 50%.

  The primary alcoholic hydroxyl group and the secondary alcohol hydroxyl group will be further described. The primary and secondary descriptions refer to the structure before the hydrogen bonded to carbon is replaced, and after the ester bond. This means that the structure can be regarded as a substitution of hydrogen bonded to carbon. The order of hydrogen substitution and ester bond is not limited.

  In the case of a structure that can be regarded as a substituted group, the original alcoholic hydroxyl group may not necessarily be a primary alcohol or a secondary alcohol in view of the structure after substitution. It is contained in ester of the diol type compound.

The diol preferably has a structure described in the following (c).
(C) Two carbons to which a hydroxyl group is bonded are both bonded to the same carbon, and the central carbon of these three carbons has no hydrogen atom.
Further, those having a total carbon number of 6 to 9 are preferably used as the diol.
Moreover, as said diol, the pentanediol which the hydrogen couple | bonded with carbon may be substituted can be used preferably.

In addition, those in which the acid component of the ester is a fatty acid having a total carbon number of 12 or less are preferably used.
In addition, those in which the acid component of the ester is butanoic acid are preferably used.
Moreover, the thing whose butanoic acid is isobutanoic acid is used preferably.

  The compound (a) is 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate, and the compound (b) is 2,2,4-trimethyl-1,3. -Pentanediol diisobutyrate is preferably used.

The plate surface cleaning agent for a lithographic printing plate of the present invention increases the hydrophilicity of the non-image area by adding phosphoric acid and / or a phosphate in addition to the ester of the specific diol compound described above, and has an antifouling effect. Rise. Specific examples of phosphoric acid and / or phosphate include condensed phosphoric acid represented by phosphoric acid, pyrophosphoric acid, and polyphosphoric acid. Examples of the phosphate include sodium salt, potassium salt, magnesium salt, calcium salt, ammonium salt and the like.
The total content of phosphoric acid and phosphate in the lithographic printing plate cleaning agent is preferably 0.1 to 10%. More preferably, it is 0.1 to 5%.

Furthermore, the lithographic printing plate surface cleaning agent of the present invention, when gum arabic is added, protects the non-image area by the gum component, and therefore improves the ability to recover stains when restarted.
The total content of the gum arabic lithographic printing plate surface cleaner is preferably 1 to 30%. More preferably, it is 3 to 20%.

  In the lithographic printing plate surface cleaning agent of the present invention, glycerin, trimethylolpropane, polyethylene glycol, D-sorbitol, or the like may be added as a water-soluble solvent for imparting hydrophilicity or storage stability of the liquid.

Furthermore, an organic acid and / or salts thereof may be added to the lithographic printing plate surface cleaner for the purpose of imparting hydrophilicity or removing water-insoluble salts.
Examples of organic acids and salts thereof include succinic acid, citric acid, ascorbic acid, malic acid, tartaric acid, lactic acid, glycolic acid, gluconic acid, oxalic acid, malonic acid, levulinic acid, phytic acid, organic phosphonic acid, and salts thereof Etc.
The total content of the organic acid and / or salt thereof in the lithographic printing plate cleaning agent is preferably 0.1 to 10%. More preferably, it is 0.1 to 5%.

  In the present invention, a polyoxyethylene alkyl ether, a polyoxypropylene alkyl ether, a polyoxyethylene polyoxypropylene block polymer is used as a nonionic surfactant to improve the solubilization of various additives and improve the detergency. It may be used.

  Furthermore, specific examples of anionic surfactants in ionic surfactants include, for example, fatty acid salts, hydroxyalkane sulfonates, alkane sulfonates, alkyl sulfosuccinates, polyoxyethylene alkyl sulfophenyl ether salts, N-methyl-N -Oleyl taurine sodium salt, N-alkylsulfosuccinic acid monoamide disodium salt, polyoxyethylene alkyl ether sulfate ester salt, fatty acid monoglyceride sulfate ester salt, alkyl phosphate ester salt, polyoxyethylene alkyl ether phosphate ester salt and the like.

  Specific examples of the cationic surfactant include alkylamine salts, quaternary ammonium salts, polyoxyethylene alkylamine salts, polyethylene polyamine derivatives, and the like.

  Other fluorine-based surfactants and silicon-based surfactants can also be used.

Examples The present invention will be described in detail with reference to examples, but the present invention is not limited to these examples.
According to the composition of Table 1, 8 plate surface cleaning agents for lithographic printing plates of Examples were prepared. Moreover, according to the composition of Table 3, the unit which prepared the plate surface washing | cleaning agent for lithographic printing plates of a comparative example was a gram, added water as remainder other than the composition of Table 1, 3, and stirred with a homomixer, and an emulsion and did. The total amount was 1000 g, respectively.

In Table 1, as the 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate, TEXANOL manufactured by Eastman Chemical Co. was used. Further, TXIB manufactured by Eastman Chemical Co. was used as 2,2,4-trimethyl-1,3-pentanediol diisobutyrate.
AF Solvent 4 is manufactured by JX Nippon Oil & Energy Corporation and has a paraffin content of about 22% and a naphthene content of about 78%.
For 3-methoxy-3-methyl-1-butanol, Kuraray Solfit was used. The sodium dialkyl sulfosuccinate used the Japan Emulsifier Co., Ltd. product.

  About Example 1-8 of this invention and Comparative Examples 1-5, it tested on the following conditions. The results are shown in Tables 2 and 4.

(A) Liquid storage stability About each Example and the comparative example, the storage stability of the liquid when it left still at room temperature was confirmed. In a state where the oil and water are separated, the original cleaning properties and desensitizing performance of the lithographic printing plate surface cleaning agent cannot be exhibited.
○: No separation for 20 days or more.
Δ: Separation in about 10 to 20 days.
X: Separation within 10 days.

(B) Plate erosion property 1.0 ml of the plate surface cleaning agent of each Example and Comparative Example was dropped on a CTP plate (SWORD-XD; manufactured by Kodak GK) with a 50% halftone dot and a solid (total image area), It was immersed for 5 hours at 40 degrees, and it was confirmed whether erosion was seen in the image area.
○ ... No image area erosion.
Δ: Erosion is observed at the liquid interface.
X: Solid part, 50% halftone dot is eroded, and the image line part is removed.

Evaluations (c) to (f) by the printing test shown below were performed. The printing conditions are as follows. The results are shown in Tables 2 and 4.
Printing machine: Roland-704 (manufactured by Man Roland).
Printing speed: 10,000 sheets / hour.
Printing paper: OK top coat.
Dampening mechanism: Rolandmatic.
Temperature and humidity: 23-24 ° C., 50-60% RH.
Oil-based ink: Fusion G EZ Red N (manufactured by DIC Graphics).
High sensitivity UV ink: Dicure HR-L Red N (manufactured by DIC Graphics).
Printing version: CTP version (SWORD-XD; manufactured by Kodak GK)

(C) Oil-based ink stain recoverability Using the above-mentioned oil-based ink, the water scale on which printing paper stains occur at the scale of the water supply amount of the printing press (scale 1 to 99, also the scale of the rotation speed of the water supply roller). As a lower limit value, about 500 sheets were printed with a standard water scale of 5% from the lower limit value. Then, after wash | cleaning the plate using the plate surface cleaning agent of each Example and a comparative example, the printing machine was stopped for 1 hour. The number of sheets on which the smudges of the printed matter recovered upon restarting was counted.
◎ ・ ・ ・ Recovers dirt within 20 sheets.
○: Dirt is recovered within 30 sheets.
Δ: Dirt is recovered within 30 to 50 sheets.
×: Dirt is recovered after printing 50 sheets or more.

(D) High-sensitivity UV ink stain recoverability Using the above-mentioned high-sensitivity UV ink, printing paper stains occur on the scale of the water supply amount of the printing press (scales 1 to 99 and also the rotation speed of the water supply roller). About 500 sheets were printed with the water scale to be used as the lower limit and the standard water scale plus 5% from the lower limit. Then, after wash | cleaning the plate using the plate surface cleaning agent of each Example and a comparative example, the printing machine was stopped for 1 hour. The number of sheets on which the smudges of the printed matter recovered upon restarting was counted.
◎ ・ ・ ・ Recovers dirt within 20 sheets.
○: Dirt is recovered within 30 sheets.
Δ: Dirt is recovered within 30 to 50 sheets.
×: Dirt is recovered after printing 50 sheets or more.

(E) Oil-based ink detergency +5 from the lower limit, with the lower limit being the water scale where printing paper stains occur on the scale of the water supply of the printing press (scale 1 to 99, also the rotation speed of the water supply roller) About 500 sheets were printed with% as the standard water scale. An appropriate amount of the plate surface cleaning agent of each Example and Comparative Example was applied to a cellulose sponge, and the plate surface was wiped off. The evaluation criteria are as follows.
○: Oil-based ink components can be completely removed.
Δ: Some oil-based ink components remain.
X: Oil-based ink components remain.

(F) High-sensitivity UV ink detergency From the lower limit, the lower limit is the water scale at which printing paper stains occur on the scale of the water supply of the printing press (scale 1 to 99, which is also the rotation speed of the water supply roller). About 500 sheets were printed with a plus 5% standard water scale. An appropriate amount of the plate surface cleaning agent of each Example and Comparative Example was applied to a cellulose sponge, and the plate surface was wiped off. The evaluation criteria are as follows.
○: Highly sensitive UV ink components can be completely removed.
Δ: Some high-sensitivity UV ink components remain.
X: A high-sensitivity UV ink component remains.

  In Examples 1 to 8, good results were obtained for all items. Comparative Example 1 was poor in liquid storage stability, stain recovery, and ink washability. In Comparative Examples 1 to 4, the high-sensitivity UV ink detergency was poor. In Comparative Example 5, the erodibility of the plate was confirmed in the plate plate erosion test.

  The plate surface cleaning agent for a lithographic printing plate of the present invention has an excellent ability to wash and remove oil-based ink and high-sensitivity UV ink on the plate surface, and does not dissolve the image area of the plate. In addition, it has a desensitizing effect on the non-image area of the plate and is a highly safe cleaning agent in the working environment.

Claims (10)

A plate surface cleaning agent for a lithographic printing plate containing at least one of the esters described in the following (a) and (b).
(A) A monoester of a diol which has a primary alcoholic hydroxyl group and a secondary alcoholic hydroxyl group in the molecule, and hydrogen bonded to carbon may be substituted, or an isomer of the monoester.
(B) Diester of diol which has a primary alcoholic hydroxyl group and a secondary alcoholic hydroxyl group in the molecule, and hydrogen bonded to carbon may be substituted, or an isomer of the diester. The lithographic printing plate printing plate cleaner according to claim 1, wherein the diol has a structure described in the following (c).
(C) The two carbons to which the hydroxyl group is bonded are both bonded to the same carbon, and the center carbon of these three carbons is not bonded to a hydrogen atom.   The lithographic printing plate printing plate cleaner according to claim 1, wherein the diol has a total carbon number of 6 to 9.   The lithographic printing plate printing plate cleaning agent according to claim 3, wherein the diol is a pentanediol optionally substituted with hydrogen bonded to carbon.   The plate surface cleaning agent for lithographic printing plates according to claim 1, wherein the acid component of the ester is a fatty acid having a total carbon number of 12 or less.   The plate surface cleaning agent for lithographic printing plates according to claim 5, wherein the acid component of the ester is butanoic acid.   The plate surface cleaning agent for a lithographic printing plate according to claim 6, wherein the butanoic acid is isobutanoic acid.   The compound of (a) of claim 1 is 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate or an isomer thereof, and the compound of (b) of claim 1 is 2,2, The lithographic printing plate printing plate cleaner according to claim 1, which is 4-trimethyl-1,3-pentanediol diisobutyrate or an isomer thereof.   The plate surface cleaning agent for a lithographic printing plate according to claim 1, comprising phosphoric acid and / or a salt of phosphoric acid.   The plate surface cleaning agent for lithographic printing plates according to claim 9, comprising gum arabic.