JPH0715076B2 - Waterless planographic printing ink composition - Google Patents

Description

TECHNICAL FIELD The present invention relates to an ink composition for waterless lithographic printing, which has good resistance to background smearing in waterless lithographic printing and has a small amount of components that evaporate during drying. It is a thing.

[Prior Art] A waterless lithographic printing method using a lithographic printing plate that does not require such a dampening solution has been proposed, as opposed to a lithographic printing method that utilizes the ink repulsion property of the dampening solution, which is currently the mainstream of printing. ,
In particular, a method of printing using a lithographic printing plate provided with silicone rubber in a non-image area has been put into practical use.

In such waterless lithographic printing, it is known that printing with a conventional oil-based ink is not preferable because it causes scumming.

The phenomenon that scumming occurs in waterless lithographic printing is due to the friction of the drive unit and rollers of the printing machine during printing, the plate surface temperature rises, the cohesive force of the ink itself decreases, and it is originally ink repellent. Ink adheres to the non-image areas that should be printed.

Such a phenomenon does not need to be considered at all in the conventional lithographic printing plate using dampening water, and is a problem peculiar to the waterless lithographic printing plate. This is because, in the case of conventional lithographic printing using dampening water, the ink repelling mechanism is different, and the rise of the plate surface temperature is considerably suppressed by the evaporation of dampening water. It is said that it is preferable that the cohesive force of the ink is rather small.

In the waterless planographic printing, when printing is performed at high speed using an offset printing machine, an offset rotary printing machine or the like, it is necessary to dry the printing ink quickly. Particularly in offset rotary printing, the printed matter is dried by direct flame or hot air in order to accelerate the drying. However, when an ordinary ink containing a large amount of solvent components is used for such printing, a large amount of solvent vapor is discharged, which deteriorates the working environment and is not preferable in terms of hygiene and safety. Furthermore, glass, metal, which has no solvent absorption,
When an ink having a large amount of a solvent component is used for printing an object to be printed such as plastic, unevenness of inking of a solid portion and poor drying may occur because the solvent does not penetrate into the object to be printed. Therefore, those skilled in the art desire an ink that can be dried by some means without containing such a volatile substance. As such an ink, as a conventional lithographic printing ink using fountain solution,
UV-curable inks and heat-curable solventless inks are known, but cannot be used for waterless lithographic plates for the above reasons.

[Problems to be Solved by the Invention] An object of the present invention is to eliminate the above-mentioned drawbacks of conventional inks,
An object of the present invention is to provide a waterless lithographic printing ink composition which is excellent in stain resistance and has a small amount of components that evaporate when dried.

[Means for Solving Problems] The object of the present invention is to provide a compound represented by the following general formula (1): (Where X is -O- or -CH ₂ -, R is a substituted or unsubstituted alkyl group or alkenyl group having 5 to 25 carbon atoms, a substituted or unsubstituted aryl group or an aralkyl group having 6 to 25 carbon atoms. The ink composition for waterless lithographic printing is characterized in that the ink contains the epoxy compound represented by the formula (5) in an amount of 5 to 40% by weight and the amount of the solvent is 10% by weight or less.

Substituents that may be included in the general formula (1) include halgen, alkoxy, alkoxycarbonyl, and cyano groups.

The epoxy compound used in the present invention has the general formula (1) (Where X is -O- or -CH ₂ -, R is a substituted or unsubstituted alkyl group or alkenyl group having 5 to 25 carbon atoms, a substituted or unsubstituted aryl group or an aralkyl group having 6 to 25 carbon atoms. ), Specifically, 2-ethylhexyl glycidyl ether, phenyl glycidyl ether, 2-methyloctyl glycidyl ether, lauryl glycidyl ether, tridecyl glycidyl ether, tetradecyl glycidyl ether, pentadecyl glycidyl ether, Stearic acid glycidyl ester, linoleic acid glycidyl ester, α-linolenic acid glycidyl ester, ricinoleic acid glycidyl ester, parachlorophenyl glycidyl ether, 10-
Methoxycarbonyl-1-dodecene oxide, heptadecanecarboxylic acid glycidyl ester, octadecanecarboxylic acid glycidyl ester, pentadecene oxide, dodecene oxide, P-methoxyphenylglycidyl ether, P-methylphenylglycidyl ether, P-cyanophenylglycidyl ether , 1,2-epoxydodecane and the like, but are not limited to these compounds.

R is a substituted or unsubstituted alkyl group or alkenyl group having 5 to 25 carbon atoms, or substituted or unsubstituted 6 carbon atoms
~ 25 aryl group or aralkyl group, preferably a substituted or unsubstituted alkyl group having 5 to 25 carbon atoms or an alkenyl group, more preferably a substituted or unsubstituted alkyl group having 10 to 20 carbon atoms or It is an alkenyl group. When R is an alkyl group or an alkenyl group and has less than 5 carbon atoms, the stain resistance is insufficient. When the carbon number of R exceeds 25, the printability becomes poor because the viscosity of the ink becomes high.

The solvent used in the present invention has a boiling point range of 20.
A hydrocarbon solvent having a temperature of 0 ° C to 350 ° C is preferably used, but not limited thereto. The amount of the solvent is 10% by weight or less in the ink composition, but preferably 5% by weight or less. If the amount of the solvent exceeds 10% by weight, the amount of the solvent that evaporates at the time of drying will increase, and pollution problems such as deterioration of the working environment are likely to occur.

In the ink composition of the present invention, the constituent resin component of the vehicle is one known in the art, for example, rosin,
Although rosin ester, phenol resin, rosin-modified phenol resin, petroleum resin and the like can be used, rosin-modified phenol resin and petroleum resin are particularly preferable.

In addition, drying oil, alkyd resin, aminoalkyd resin,
Resins that cure by oxidative polymerization, such as urethane-modified alkyd resins, can be used, but the amount used is preferably 10% by weight or less in the ink composition.

Further, it is also possible to use a polyfunctional epoxy resin, and when these are used, it is preferable that the amount is 5% by weight or more and 30% by weight or less in the ink composition.

Further, a compound which reacts with an epoxy group and is heat-curable, for example, an acid anhydride, an amine, a compound having a phenol group, a carboxylic acid, a compound having an alcoholic hydroxyl group,
Those having an isocyanate group, those having a methylol group, and those having a methylol ether group can be used, and an acid anhydride is particularly preferable. When these are used, it is preferably 1% by weight or less and 20% by weight or less in the ink composition.

Further, dicyandiamide, tertiary amines, boron trifluoride-amine complex, etc., which are self-condensation catalysts for epoxy compounds, can also be used.

Further, as the colorant, those used in conventional ink compositions such as inorganic or organic pigments are used.

In addition, for example waxes, greases, desiccants, dispersants,
Fillers and other known materials can also be used.

When adding the epoxy compound represented by the formula (1), it may be added to the varnish or may be added and mixed into the finished ink in the intermediate step of the ink production. Is preferred.

The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. The parts used in the examples are based on parts by weight.

[Examples] Example 1 40 parts of rosin-modified phenolic resin and 40 parts of glycidyl stearate were mixed under a nitrogen flow and heated to 200 ° C.
After heating and stirring for 1 hour at 20 ° C., the temperature was lowered, 20 parts of Epicoat 808 (epoxy resin manufactured by Shell Sekiyu KK) was added at 100 ° C., and the mixture was heated and stirred at 100 ° C. for 30 minutes.

Using the varnish A thus obtained, an ink A was obtained by kneading with the following composition by a conventional method using a three-roll mill.

Ink A Carbon black 20.0 parts Alkali blue toner 10.0 parts Varnish A 60.0 parts 4-Methylhexahydrophthalic anhydride 10.0 parts Total 100.0 parts Ink A had a scumming index of 40. Ink A
Was used to print on a glass plate using a waterless planographic printing plate having a non-adhesive layer made of silicone rubber without supplying dampening water to the plate surface with a proofing machine.

As a result, a good printed matter without scumming was obtained.

Further, when the weight change before and after the printed glass plate was dried at 250 ° C. for 30 minutes was measured, the weight change was not recognized within the error range.

Evaluation method for resistance to scumming (measurement of scumming index) A waterless lithographic printing plate with a non-adhesive layer made of silicone rubber was attached to a printing machine that was modified so that the plate surface could be heated by passing warm water through the plate cylinder. Printing was performed while the plate surface was heated without supplying dampening water, and the plate surface temperature at the time when a background stain was generated on the printed matter at a constant solid density was defined as a background stain generation index. The ink having a higher scumming index is less likely to cause scumming in practical printing.

Example 2 Ink B was obtained by kneading varnish A with the following composition by a conventional method using a three-roll mill.

Ink B Phthalocyanine Blue 20.0 parts Varnish A 70.0 parts 4-Methylhexahydrophthalic anhydride 10.0 parts Total 100.0 parts Ink B had a stain generation index of 37. Further, the ink B was printed on the glass plate in the same manner as in Example 1, and as a result, a good printed matter without scumming was obtained.

Further, when the weight change before and after the printed glass plate was dried at 250 ° C. for 30 minutes was measured, the weight change was not recognized within the error range.

[Effects of the Invention] Since the waterless lithographic printing ink composition of the present invention is constituted as described above, it can be satisfactorily printed on the non-image area without scumming. In addition, since the ink contains a small amount of solvent components, there are few components that evaporate during drying, and the working environment is not deteriorated. Further, when it is used for printing an object to be printed such as glass, metal or plastic film having no solvent absorption, a printed object having good solid inking can be obtained without causing problems such as poor drying.

Claims (1)

[Claims] 1. The following general formula (1) (Where X is -O- or -CH ₂ -, R is a substituted or unsubstituted alkyl group or alkenyl group having 5 to 25 carbon atoms, a substituted or unsubstituted aryl group or an aralkyl group having 6 to 25 carbon atoms. ) An ink composition for waterless lithographic printing, characterized in that the ink contains the epoxy compound represented by 5) in an amount of 5 to 40% by weight, and the amount of the solvent is 10% by weight or less.