JPH05287228A - Offset ink composition curable with active energy ray - Google Patents

Abstract

PURPOSE:To greatly widen the range or suitable amt. of dampening water during printing with on offset ink compsn. by merely adding a synthetic resin emulsion to the compsn. without changing the formulation of vehicle. CONSTITUTION:A synthetic resin emulsion is added to the subject compsn. contg. an ethylenically unsatd. polymerizable compd.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an active energy for offset printing which is cured by irradiation with an active energy ray such as an ultraviolet ray or an electron beam and exhibits excellent density stability against variations in the amount of dampening water supplied in offset printing. The present invention relates to a line-curable ink composition.

[0002]

2. Description of the Related Art In offset printing, printing is performed on paper, plastic sheet, surface-treated paper, etc. using a plate composed of an image-forming portion that receives oil-based ink and a non-image-forming portion that receives dampening water. . Therefore, during printing, the ink and the dampening water are always in contact with each other on the plate surface, and the dampening water is in an emulsified state in the ink. Therefore, in order to obtain high-quality printed matter and to print without causing various printing problems such as stains and residue, make sure that the surface tension and interfacial tension of the ink and dampening water are always kept in an appropriate balance. , It is necessary to design the ink.

In recent years, plastic sheets, surface-treated paper,
In offset printing using paper or the like as an object to be printed, ultraviolet ray and electron beam curable ink is often used so that the ink is instantaneously cured at room temperature. However, when these inks are used, it is generally said that it is difficult to balance with dampening water and it is difficult to print as compared with oil-based sheet-fed printing inks that use oxidative polymerization as a curing method. is there. As a cause, compared with oil-based sheet-fed printing ink,
The resin content in the ink is low, which results in low ink viscoelasticity. It is also considered that the dampening water is easily emulsified because a large amount of the reactive monomer used in the ink has high polarity.

In addition, since materials such as plastic sheets and surface-treated paper do not absorb water, it is more difficult to adjust the amount of dampening water as compared with offset printing of paper that absorbs moderate water. If the amount of dampening water supplied is too small, the printing density will rise rapidly, and eventually scumming will occur.On the contrary, if the amount of dampening water supplied is too large, the ink will be emulsified above the appropriate conditions. As a result, the print density is extremely lowered.

In order to improve this point, it has been proposed to add various auxiliaries. For example, control the emulsified state.
Speaking of general surfactants as auxiliary agents,
When added to the ink without considering the HLB value and the appropriate amount, the fluidity of the ink is seriously impaired, and the phenomenon that the ink is entangled with the roller supplying the dampening water and accumulated is observed. As a result, the printing stability in long-run printing deteriorated, which was not satisfactory. The lower limit of the appropriate supply amount of dampening water that does not cause stains and the upper limit of the appropriate supply amount of dampening water that does not cause a drastic decrease in printing density and water marks are called the water width. Ink development is required.

[0006]

SUMMARY OF THE INVENTION In order to solve the problems of the conventional inks, the present invention controls the wettability with dampening water to provide excellent concentration stability against fluctuations in the amount of dampening water supplied. That is, an active energy ray curable ink composition for offset printing having a wide water width is provided.

When the active energy ray-curable ink for offset printing containing a polymerizable compound having an ethylenically unsaturated double bond and, if necessary, a photopolymerization initiator, is wet-printed with a dampening water, An auxiliary agent that makes the ink difficult to emulsify with water and imparts viscoelasticity to the ink,
In other words, it is expected that the ink will not be excessively emulsified by the dampening water by using a polymer compound that increases the contact angle of the ink with water, in combination with the ink.
The present inventors arrived at the present invention as a result of conducting a search for such an auxiliary agent.

[0008]

SUMMARY OF THE INVENTION The present invention provides an active energy ray curable ink for offset printing containing a polymerizable compound having an ethylenically unsaturated double bond, which comprises a synthetic resin emulsion. The present invention relates to an active energy ray curable ink composition for printing.

In the present invention, as the polymerizable compound having an ethylenically unsaturated double bond, a monomer having an average molecular weight of less than 1000 and an ethylenically unsaturated double bond, and an ethylenically unsaturated double bond having an average molecular weight of 1000 or more are used. Oligomers having a heavy bond can be used. Acryloyl group as the functional group of the ethylenically unsaturated double bond,
Examples thereof include a methacryloyl group, an allyl group, and a methallyl group, but it is preferable to use a compound having at least an acryloyl group or a methacryloyl group (hereinafter abbreviated as a (meth) acryloyl group) from the viewpoint of curability.

Specific examples of the above-mentioned monomer include tripropylene glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, ethoxytrimethylolpropane tri (meth) acrylate and glycerolpropane trichloride. (Meth) acrylate, propoxytrimethylolpropane tri (meth) acrylate,
Pentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, etc. may be mentioned. Good.

As the above-mentioned oligomer, unsaturated polyester, polyester (meth) acrylate, epoxy (meth) acrylate, rosin-modified epoxy (meth) are used.
Various chemically modified epoxy (meth) acrylates represented by acrylates, polyester urethane (meth) acrylates and diallyl phthalate resins can be mentioned, and they may be used in combination.

In the present invention, a photopolymerization initiator is optionally used, and examples of the photopolymerization initiator that can be used include benzoin, benzoin methyl ether, benzoin ethyl ether, and benzoin isopropyl ether. Benzoin and benzoin alkyl ethers, acetophenone, 2,2-dimethoxy-2-acetophenone, 2,
Acetophenones such as 2-diethoxy-2-acetophenone, 1,1-dichloroacetophenone, 2-methylanthraquinone, 2-ethylanthraquinone, 2-ta-
Anthraquinones such as shari-butyl anthraquinone, 1-chloroanthraquinone and 2-amylanthraquinone, thioxanthones such as 2,4-dimethylthioxanthone, 1-chlorothioxanthone and 2,4-diisopropylthioxanthone, acetophenone dimethylketane
And benzyl dimethyl ketal, benzophenones such as benzophenone or its derivatives, and the like, and such photopolymerization initiators may be benzoic acid ester-based compounds or tertiary amine-based compounds known in the art. Sensitizer 1
It is also possible to use one kind or a combination of two or more kinds.

As the synthetic resin emulsion used in the present invention, any synthetic resin emulsion obtained by polymerization of a polymerizable monomer can be used. For example, acrylic acid or its ester, methacrylic acid or its ester, Unsaturated carboxylic acids such as maleic acid, itaconic acid and fumaric acid or esters thereof, acrylamide or derivatives thereof, acrylonitrile, styrene, butadiene, isoprene, chloroprene, vinyl acetate, vinyl propionate, VeoVa911, vinyl chloride, vinylidene chloride, ethylene, SBR (styrene butadiene rubber) latex, NBR (acryl) obtained by any polymerization method such as emulsion, suspension or solution of a monomer such as propylene, isobutylene, allyl alcohol or its ester or ether. Nitrile butadiene rubber) latex such as synthetic rubber latex, PVAc (polyvinyl acetate) latex, copolymer latex obtained by copolymerization of vinyl acetate and other comonomers, acrylic homopolymer or copolymer latex, and polyester resin , A graft polymer latex with a polyurethane resin, a carboxyl group in the polymer molecular chain, N-methylo-
Examples thereof include modified synthetic rubber latexes having a functional group such as a vinyl group, a glycidyl group, a hydroxyl group, an amino group, an amide group, and an acid anhydride, and a modified synthetic rubber latex is particularly preferable.

The amount of the synthetic resin emulsion added to the ink is in the range of 0.1% by weight to 5.0% by weight as the resin solid content of the emulsion, the compatibility with the ink, the viscoelasticity of the ink, and the type of material used. It is preferable to select an appropriate amount depending on (particularly pigment), and it is more preferable to select within a range of 0.5 to 3.0% by weight as the resin solid content of the emulsion. Even if the synthetic resin emulsion is added to the ink in a range of less than 0.1% by weight as the resin solid content of the emulsion, the effect of decreasing the polarity of the ink is small and it is very useful for stabilizing the density during offset printing. Absent. On the other hand, if the amount added exceeds 5.0% by weight, the compatibility with the ink is poor and the viscosity increases, and the ink transferability on the printing machine deteriorates. When the amount of the synthetic resin emulsion is in the range of 0.1% by weight to 5.0% by weight as the resin solid content, the curing ability by ultraviolet rays and electron beams is not impaired.

When the synthetic resin emulsion is added, the same effect can be obtained by mixing it with other materials at the same time before the ink manufacturing step or by adding it to the already completed ink later.

Further, the active energy ray curable ink composition for offset printing of the present invention contains an arbitrary resin such as saturated polyester containing no ethylenically unsaturated double bond,
Furthermore, organic pigments, inorganic pigments or extender pigments, and ink aids may be used in combination. The amount of these used can be arbitrarily set according to the printability of the ink, the curability, and the physical properties of the cured film. Generally, when the total amount of the ink composition is 100% (% by weight), the oligomer is used. 5-80%, monomer; 5-80%, polymerization initiator (including sensitizer); 0-15%, color pigment; 0-25
%, Extender pigment; 0-40%, resin not containing ethylenically unsaturated double bond; 0-40%, ink aids; 0-10
It is preferably used in the range of%.

[0017]

EXAMPLES The present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to the contents. However, "%" in the examples means "% by weight". The ink was prepared by kneading with a three-roll mill according to a conventional method.

Example 1 An ultraviolet curable ink base for offset was manufactured with the following composition. Fast Gembre- (Dai Nippon Ink Chemical Co., Ltd. Phthalocyanine pigment) 18.0% Calcium carbonate 2.0% 2-Methyl-1- (4-methylthio) -2-5.0% Morpholinopropanone-1 t- Butylhydroquinone 0.05% Diallyl phthalate resin (Note) 12.0% Dipentaerythritol hexahexaacrylate 49.5% Trimethyl propane triacrylate 13.45% 100.0% (Note) Osaka Soda Co., Ltd. Daiso-Dup A

Ink-1 is obtained by further kneading 3.1% of SBR latex manufactured by Dainippon Ink and Chemicals, Inc., DS-205 (nonvolatile content 48%) against 96.9% of the above base.

Example 2 NBR latex DN-704 (nonvolatile matter content 46.5%) manufactured by Dainippon Ink and Chemicals, Inc. was used for 3.2% against the same ultraviolet curable ink base for offset as in Example 1 (96.8%). %
Further, the kneaded meat is used as ink-2.

Example 3 The same UV-curable ink base for offset as in Example 1 (97.0%) was used, and PVAc latex VONCOAT 2830 (nonvolatile matter: 50.0) made by Dainippon Ink and Chemicals, Inc. was used.
%) Was further kneaded to obtain Ink-3.

Example 4 The same UV-curable ink base for offset as in Example 1 (97.0%) was used, and VONCOAT 3111 (nonvolatile content: 5) was used as an acrylic copolymer latex manufactured by Dainippon Ink and Chemicals.
Ink-4 is a mixture of 0.0%) and 3.0%.

Example 5 The same UV-curable ink base for offset as in Example 1 (96.8%) was mixed with 3 stars of LACSTAR 4709A (nonvolatile content: 47.0%), a carboxy-modified SBR latex manufactured by Dainippon Ink and Chemicals, Inc. 0.0% ink that is further kneaded
Set to 5.

Comparative Example 1 Ink-6 is the same as in Example 1 except that 97.0% of UV curable ink base for offset was used and 3.0% of trimethylolpropane triacrylate was further kneaded. .

Comparative Example 2 Oil-based sheet-fed indigo ink for offset printing GRA manufactured by Dainippon Ink and Chemicals, which is generally recognized to have a wider water width than the active energy ray curable ink for offset printing.
Ink-7 is used for FG indigo.

The contact angles of the above 7 inks and fountain solution (the same ones used under the following sheet-fed lithographic printing conditions) were measured by Shimadzu's automatic contact angle meter; ST-1S. It is summarized in Table 1. The higher the polarity of the ink, the easier it becomes to get wet with the dampening water, and the smaller the contact angle. That is, the polarity of the ink can be determined by comparing this value. Further, the above 7 points of ink were subjected to sheet-fed lithographic printing under the following conditions, and the width of the appropriate supply amount of dampening water (water width) was measured by a meter provided in the printing machine. Two results were obtained.

Sheet-fed lithographic printing conditions Printer: R-201 PS plate made by Roland; Positive type PS made by Polychrome Japan
Edition RP Blanket; Sumitomo Rubber Dunlop R-70 Paper; Tojo Paper Diamond Coat (Sixty-four plate is used for four-plant) Dampening water; Domestic chemical isopropyl alcohol to 95% by weight of tap water (first grade) NT liquid K70 manufactured by Dainippon Ink and Chemicals, using the solution obtained by adding 5% by weight
1 400 times diluted Printing speed: 8000 sheets / h Room temperature: 25 ± 1 ° C

Specifically, the scale 30 of the dampening water supply device
Printing is started with (a dial scale value of a standard amount of supplied water), after printing about 2000 sheets, the scale of the supply device is lowered to 25, 20, 15. About 200 sheets were printed at each scale setting, and the scale value at which the background stain occurred and the degree of stain were recorded. Next, set the feeder scale to 30
Then, the scale was increased to 30, 40, 45, and 50, and the scale and degree at which the water mark was confirmed were recorded in the same manner as when the scale was lowered. The range of the scale value where the background stain is generated to the scale value where the water mark is generated is the water width, and the wider the range, the better the workability of the ink.

As is clear from the results shown in Table 1, the inks 1 to 5 of the examples have a contact angle value of 15 ° or more larger than the ink 6 of the comparative example 1 and are hard to wet with dampening water. It was confirmed that the value of Ink-7 of Comparative Example 2 was approached.

Further, as is clear from the results in Table 2, the ink widths of Inks-1 to 5 of Examples are wider than that of Ink-6 of Comparative Example 1, and the print density with respect to the fluctuation of the amount of dampening water supplied. Increased stability. Even when compared with the water width of Ink-7 of Comparative Example 2, the water widths of the inks of Examples 1, 3, and 4 having close contact angle values were improved to almost the same level.

[0031]

[Table 1]

[0032]

[Table 2]

[0033]

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to obtain an active energy ray-curable ink composition for offset printing, which exhibits excellent concentration stability against variations in the amount of dampening water supplied in offset printing.

Claims (3)

[Claims] 1. An active energy ray curable ink composition for offset printing containing a polymerizable compound having an ethylenically unsaturated double bond, wherein an active energy ray for offset printing containing a synthetic resin emulsion. Curable ink composition. 2. The active energy ray curing for offset printing according to claim 1, wherein the synthetic resin emulsion is an unmodified or modified synthetic rubber latex, a vinyl acetate latex, a vinyl acetate copolymer latex or an acrylic copolymer latex. Type ink composition. 3. A synthetic resin emulsion comprising a conjugated diene of butadiene or isoprene (first component), a vinyl monomer (second component) copolymerizing with these, a carboxyl group, an N-methylol group, a glycidyl group, A modified synthetic rubber latex obtained by copolymerizing a reactive monomer (third component) having a crosslinkable reactive group selected from the group consisting of a hydroxyl group, an amino group, an amide group and an acid anhydride as a side chain. The active energy ray curable ink composition for offset printing according to claim 1.