JP5560872B2 - Active energy ray-curable offset ink composition and printed matter thereof - Google Patents

Description

The present invention relates to an active energy ray-curable ink composition and a printed material obtained by printing the composition. More specifically, the present invention relates to an active energy ray-curable offset ink composition having excellent workability and excellent transferability necessary for obtaining stable printing quality, and a printed material obtained by printing the composition.

  Conventionally, active energy ray curable coating compositions have been actively studied, and in particular, they are being put to practical use in the fields of printing inks, clear varnishes, paints and the like. In particular, the active energy ray-curable offset ink is a non-reactive resin (inert resin) having a melting point of 50 ° C. or more, typified by diallyl phthalate resin, or a radical polymerizable oligomer, a radical polymerizable monomer, and a radical polymerization initiator or light as required. It consists of sensitizers, pigments, and various additives. Ortho or isotype diallyl phthalate resins are widely used as non-reactive resins (inert resins). Alkyd acrylate, polyester acrylate, epoxy acrylate, urethane-modified acrylate, etc. are used as radically polymerizable oligomers. Bisphenol A alkylene oxide adduct diacrylate, ethylene glycol diacrylate, propylene glycol diacrylate, polyethylene glycol diacrylate, neopentyl glycol diacrylate, trimethylolpropane triacrylate, tetramethylolmethane (tri or) tetraacrylate as radical polymerizable monomer Dipentaerythritol (penta or) hexaacrylate and the like are used. As radical polymerization initiators and photosensitizers, benzoin, (dialkyldiamino) aryl ketones, and xanthones are used.

  On the other hand, offset printing forms an image using a plate composed of an image area that receives oleophilic ink and a non-image area that holds dampening water, and the ink in the image line area passes through a blanket. Printed matter is obtained by transferring to paper, plastic sheet, surface-treated paper or the like. Therefore, during printing, the ink and the fountain solution are always in contact with each other on the plate surface, and the fountain solution is emulsified in the ink. If the emulsified state of the ink and fountain solution is appropriate, a good print can be obtained, but due to reasons such as temperature changes during printing, destabilization of the supply amount of fountain water, and changes in the properties of the fountain solution Ink may be excessively emulsified. As a result, problems such as a decrease in the density of printed matter, a deterioration in halftone dot reproducibility, a volume of ink that has failed to transfer to the plate surface / blanket surface (pyling), and a background stain that causes ink to adhere to non-image areas are induced.

  In particular, when an active energy ray-curable ink is used, the resin molecular weight of the binder used is smaller than that of oil-based sheet-fed printing inks that use oxidative polymerization as a curing mode, and furthermore, as radically polymerizable oligomers and radically polymerizable monomers. Due to the high polarity (hydrophilicity) of the composition used, there is a problem that it is difficult to impart cohesive force to the ink and tends to promote excessive emulsification of dampening water, and the frequency of the above troubles is high. is there.

  In order to solve the above problems, measures such as increasing the contrast of ink, adding cohesive force by lowering the pigment concentration and increasing the binder, and reducing the supply amount of dampening water by increasing the pigment concentration have been taken so far. It was done. However, these cause problems such as deterioration of ink transferability and increased frequency of scumming.

JP 2005-015755 A

  In the present invention, in offset printing, ink is prevented from being excessively emulsified due to changes in temperature during printing, destabilization of the supply amount of dampening water, changes in properties of dampening water, etc., and printability is impaired. Active energy ray-curable offset that can suppress the deterioration of print quality by reducing the density of printed matter, deterioration of halftone dot reproducibility, and the volume of ink that has failed to transfer to the plate or blanket surface (piling). An ink composition is provided.

  As a result of intensive studies on the emulsification behavior of ink and fountain solution in order to solve the above problems, the ability to take up the ink fountain solution is improved, so that the change in viscoelasticity due to emulsification is small and the speed of emulsification is improved. As a result, it has been found that this solves problems such as smearing and ink transfer failure during printing, and the present invention has been completed.

（式中、Ｒ１は、炭素数６〜１８の飽和の直鎖または分岐の脂肪族炭化水素基を示し、
Ｒ２は、炭素数２〜３の飽和の直鎖または分岐の脂肪族炭化水素基を示す。
ｎは２である。） That is, the present invention comprises an active energy ray-curable offset ink comprising a glycol ether represented by the general formula (1), a radical polymerizable monomer, a radical polymerization initiator, a sensitizer, and a pigment. a composition,
The present invention relates to an active energy ray-curable offset ink composition containing 0.1 to 5% of glycol ether represented by the general formula (1) with respect to the entire composition.
General formula (1)

(In the formula, R1 represents a saturated linear or branched aliphatic hydrocarbon group having 6 to 18 carbon atoms,
R2 represents a saturated linear or branched aliphatic hydrocarbon group having 2 to 3 carbon atoms.
n is 2. )

The present invention also relates to the above active energy ray-curable offset ink composition, wherein the radical polymerizable monomer is a monomer having an ethylenically unsaturated double bond having a weight average molecular weight of 100 to 6000. is there.
Furthermore, this invention relates to said active energy ray hardening-type offset ink composition characterized by containing a non-reactive resin further.
The present invention also relates to a printed matter obtained by printing the active energy ray-curable offset ink composition on a substrate.

（式中、Ｒ１は、炭素数６〜１８の飽和の直鎖または分岐の脂肪族炭化水素基を示し、
Ｒ２は、炭素数２〜３の飽和の直鎖または分岐の脂肪族炭化水素基を示す。
ｎは２である。） By including the glycol ether represented by the general formula (1) in the active energy ray-curable ink, it is less susceptible to excessive emulsification of dampening water in offset printing, and maintains the optimum emulsified state, thereby allowing the plate surface and blanket. Suppresses troubles such as the volume (piling) of ink that has failed to transfer to the surface. As a result, it is possible to suppress a decrease in the density of the printed matter and to improve the halftone dot reproducibility, and a stable print quality can be obtained.
General formula (1)

(In the formula, R1 represents a saturated linear or branched aliphatic hydrocarbon group having 6 to 18 carbon atoms,
R2 represents a saturated linear or branched aliphatic hydrocarbon group having 2 to 3 carbon atoms.
n is 2. )

First, an example of the active energy ray-curable ink composition used in the present invention is listed below.
・ Non-reactive resin 0-30% by weight
・ Radically polymerizable monomer 5-60% by weight
・ Pigments (organic pigments / inorganic pigments) 5-30% by weight
・ Radical polymerization initiator and sensitizer 1-15% by weight
・ Glycol ether 0.1-1% by weight
・ Additives 0-10% by weight

Further preferably, it is as follows.
・ Non-reactive resin 5-30% by weight
・ 5 to 50% by weight of (meth) acrylate monomer as radical polymerizable monomer
・ Pigments (organic pigments / inorganic pigments) 5-30% by weight
・ Radical polymerization initiator and sensitizer 1-15% by weight
・ Alkyl diglycol ether 0.1-1% by weight
・ Additives 1-10% by weight

The non-reactive resin is a thermosetting or thermoplastic resin that does not have a reactive functional group such as an ethylenically unsaturated double bond, and has a weight average molecular weight of 10,000 to 1 × 10 ⁶ . Examples of the thermosetting or thermoplastic resin include polyvinyl chloride, poly (meth) acrylic acid ester, epoxy resin, polyurethane resin, cellulose derivatives (for example, ethyl cellulose, cellulose acetate, nitrocellulose), vinyl chloride-vinyl acetate copolymer Examples thereof include synthetic rubbers such as coalescence, polyamide resin, polyvinyl acetal resin, diallyl phthalate resin, and butadiene-acrylonitrile copolymer. These resins can be used alone or in combination of two or more thereof. In any case, a resin that is soluble in a monomer having an ethylenically unsaturated double bond having a weight average molecular weight of 100 to 6000 is used.

In the present invention, the radical polymerizable monomer is preferably a monomer having an ethylenically unsaturated double bond having a weight average molecular weight of 100 to 6000, and a monomer having an ethylenically unsaturated double bond having a weight average molecular weight of 100 to 6000. -Monofunctional or polyfunctional (meth) acrylates and-Oligomers with ethylenically unsaturated double bonds (reactive oligomers)
The viscosity of the ink composition can be adjusted by appropriately using these.

A monomer having an ethylenically unsaturated double bond having a weight average molecular weight of 100 to 6000 is used in a range of 5 to 60% by weight based on the ink composition.
The weight average molecular weight of a monomer having an ethylenically unsaturated double bond having a weight average molecular weight of 100 to 6000 is a molecular weight calculated from the structural formula in the case of monofunctional or polyfunctional (meth) acrylates, In the case of an oligomer having an ethylenically unsaturated double bond (reactive oligomer), it indicates a weight average molecular weight and is determined by the following measurement.

As a weight average molecular weight of the monomer which has an ethylenically unsaturated double bond, 100-6000 are good and 200-5000 are preferable.
In the present invention, the weight average molecular weight was measured by gel permeation chromatography (HLC-8020, hereinafter referred to as GPC) manufactured by Tosoh Corporation. A calibration curve was prepared with a standard polystyrene sample. Tetrahydrofuran was used as the eluent, and three TSKgel SuperHM-M (manufactured by Tosoh Corporation) were used as the column. The measurement was performed at a flow rate of 0.6 ml / min, an injection volume of 10 μl, and a column temperature of 40 ° C.

  In the present invention, alkyl (having 2 to 18 carbon atoms) (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, hexyl (meth) acrylate, octyl (meth) acrylate, dodecyl (meth) as a monofunctional monomer Examples thereof include acrylate and stearyl (meth) acrylate, and examples include benzyl (meth) acrylate, isobornyl (meth) acrylate, cyclohexyl (meth) acrylate, tricyclodecane monomethylol (meth) acrylate, and the like.

  In the present invention, polyfunctional (meth) acrylates include ethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, dipropylene glycol di (meth) acrylate, and tripropylene. Glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, butylene glycol di (meth) acrylate, pentyl glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, hydroxypivalyl hydroxypivalate di (meth) Acrylate (commonly called manda), hydroxypivalyl hydroxypivalate dicaprolactonate di (meth) acrylate, 1,6 hexanediol di (meth) acrylate, 1 8-octanediol di (meth) acrylate, 1,9-nonanediol di (meth) acrylate, 1,2-hexadecanediol di (meth) acrylate, 2-methyl-2,4-pentanediol di (meth) acrylate, Bisphenol A tetraethylene oxide adduct di (meth) acrylate, bisphenol F tetraethylene oxide adduct di (meth) acrylate, water-added bisphenol A tetraethylene oxide adduct di (meth) acrylate, water-added bisphenol F tetraethylene oxide adduct Di (meth) acrylate, water-added bisphenol A di (meth) acrylate, water-added bisphenol F di (meth) acrylate, glycerin tri (meth) acrylate, trimethylolpropane tri (meth) acrylate , Trimethylolpropane tricaprolactonate tri (meth) acrylate, trimethylolethane tri (meth) acrylate, trimethylolhexane tri (meth) acrylate, trimethyloloctane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, penta Erythritol tetra (meth) acrylate, diglycerin tetra (meth) acrylate, ditrimethylolpropane tetra (meth) acrylate, ditrimethylolpropane tetracaprolactonate, tetra (meth) acrylate, ditrimethylolethane tetra (meth) acrylate, ditrimethylol Butanetetra (meth) acrylate, ditrimethylolhexanetetra (meth) acrylate, ditrimethyloloctanetetra (meta Use of acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, tripentaerythritol hexa (meth) acrylate, tripentaerythritol hepta (meth) acrylate, tripentaerythritol octa (meth) acrylate, etc. Can do.

  As the oligomer (reactive oligomer) having an ethylenically unsaturated double bond used in the present invention, alkyd acrylate, epoxy acrylate, urethane-modified acrylate and the like are used.

  The radical polymerization initiator used in the present invention includes benzophenone, 4,4-diethylaminobenzophenone, diethylthioxanthone, 2-methyl-1- (4-methylthio) phenyl-2-morpholinopropan-1-one, 4 -Benzoyl-4'-methyldiphenyl sulfide, 1-chloro-4-propoxythioxanthone, isopropylthioxanthone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-hydroxy-cyclohexyl-phenyl ketone, bis- 2,6-dimethoxybenzoyl-2,4,4-trimethylpentylphosphine oxide, 1- [4- (2-hydroxyethoxy) -phenyl] -2-hydroxy-2-methyl-1-propan-1-one, 2,2-dimethyl-2-hydroxyacetate Phenone, 2,2-dimethoxy-2-phenylacetophenone, 2,4,6-trimethylbenzyl-diphenylphosphine oxide, 2-benzyl-2-dimethylamino-1- (morpholinophenyl) -butan-1-one, etc. Is mentioned. A sensitizer such as p-dimethylaminobenzoic acid ethyl ester or pentyl 4-dimethylaminobenzoate may be used in combination with the photopolymerization initiator.

  Examples of additives include anti-friction agents, anti-blocking agents, slip agents, and anti-scratch agents, such as carnauba wax, wax, lanolin, montan wax, paraffin wax, microcrystalline wax, and Fischer-Trops wax. Synthetic waxes such as polyethylene wax, polypropylene wax, polytetrafluoroethylene wax, polyamide wax, silicone additives, leveling agents, constitutions, etc. can be used.

（式中、Ｒ１は、炭素数６〜１８の飽和の直鎖または分岐の脂肪族炭化水素基を示し、
Ｒ２は、炭素数２〜３の飽和の直鎖または分岐の脂肪族炭化水素基を示す。
ｎは２である。）


The glycol ether used in the present invention is an ether in which ethylene glycol or propylene glycol is bonded to a C6 to C18 linear or branched alkyl group.
The glycol ether used in the present invention is represented by the general formula (1), and in particular, R1 having 6 to 12 carbon atoms and n = 2 diglycol ether is more preferable.
General formula (1)

(In the formula, R1 represents a saturated linear or branched aliphatic hydrocarbon group having 6 to 18 carbon atoms,
R2 represents a saturated linear or branched aliphatic hydrocarbon group having 2 to 3 carbon atoms.
n is 2. )

When the carbon number of R1 exceeds 20, the compatibility with the radical polymerizable monomer is poor, and separation occurs in the ink during printing, resulting in poor transfer.
Further, when the amount of glycol ether added is less than 0.1%, the effect is low, and when it exceeds 5%, scumming occurs.

EXAMPLES The present invention will be specifically described as examples, but the present invention is not limited to the following examples. In the present invention, “part” represents “part by weight”, and “%” represents “% by weight” unless otherwise specified. The numbers in Tables 1 and 2 represent “% by weight”.
When the non-reactive resin is included in the formulation, the non-reactive resin and the monomer are preliminarily heated and heated (the upper limit temperature is kept at 100 ° C.), and the non-reactive resin is dissolved in the monomer.
The ink composition is stirred and mixed using a butterfly mixer at the prescribed blending ratio shown in Table 1, and dispersed with a three roll so that the maximum particle size is 7.5 μm or less to prepare an ink composition. Each ink composition was prepared by adjusting the viscosity with a spread meter so as to achieve a certain viscosity standard.

  Here, non-reactive resin 1 uses diallyl phthalate resin, monomer 1 uses dipentaerythritol penta (hexa) acrylate, monomer 2 uses ditrimethylolpropane tetraacrylate, and monomer 3 uses trimethylolpropane 3EO-added triacrylate.

<Method for evaluating printed matter>
Each active energy ray-curable offset ink composition was printed at 8000 sheets per hour on Maricote paper manufactured by Hokuetsu Paper Co., Ltd. using Lislon 26, a Komori Corporation sheet-fed printing press. In addition, 1.5% of Aqua Unity C manufactured by Toyo Ink Manufacturing Co., Ltd. was added to the fountain solution, and cured with an air-cooled metal halide UV lamp 120w / cm2 lamp and a mercury lamp 120w / cm1 lamp manufactured by Eye Graphics. The amount of dampening water supplied is controlled by a water dial, and printing is performed at three levels from 10 to 20 to 30. The halftone dot reproducibility was evaluated, and the results are shown in Table 3.

(Bran Piling)
At each fountain solution supply amount, the piled state on the blanket was visually observed to evaluate the presence or absence of deposits. If deposits were present on the blanket, it was judged that the ink transferability was impaired due to excessive emulsification of the fountain solution.
○: No deposit on the blanket is confirmed.
Δ: Slight deposits are confirmed on the blanket.
X: Deposits are confirmed on the blanket.

(Dirt)
Regarding the printed matter at each dampening water supply amount, the stain on the non-image area was visually observed and evaluated.
○: Soil is not confirmed.
X: Dirt is confirmed.

(Halftone dot reproducibility)
With respect to the printed matter at each fountain solution supply amount, a dot gain value was measured for a 50% halftone dot portion using an X-Rite 938 spectrophotometer manufactured by X-Rite.
When the dot gain value was 15% or less, good halftone dot reproducibility was obtained, and it was evaluated that there was no problem in print quality. When the dot gain was 20% or more, it was evaluated that the halftone dot reproducibility was poor and the print quality was affected.
In addition, about the medium ink using the inorganic pigment (calcium carbonate) shown in Examples 5-7 and Comparative Examples 5-6, the background stain and halftone dot reproducibility were evaluated by adding 3% indigo ink. .

<Maximum emulsification rate measurement>
Using the DUKE tester D10F type manufactured by DUKE CUSTOM SYSTEM INK, the maximum emulsification rate capable of incorporating purified water was measured for the inks having the formulations shown in the examples and comparative examples. When the maximum emulsification rate of each ink is high, the ability to take up dampening water is high even under conditions of excessive supply of dampening water, making it possible to maintain the optimal emulsified state. Troubles such as the volume (piling) of ink that has failed to transfer to the blanket surface can be suppressed.

  As shown in Table 1, the active energy ray-curable offset inks of Examples 1 to 7 using an alkyl diglycol ether have good halftone dot reproducibility and do not generate blanking and background staining. Any of the active energy ray-curable offset inks, blank pilings, halftone dot reproducibility, and background stains of Examples 1 to 6 was poor, and all of them were not good. As shown in Table 2, it was confirmed that the maximum emulsification rate of the active energy ray-curable offset ink using the same organic pigment / inorganic pigment was increased by using the alkyl diglycol ether shown in Examples 1-7. The

Claims (4)

An active energy ray-curable offset ink composition comprising a glycol ether represented by the general formula (1), a radical polymerizable monomer, a radical polymerization initiator, a sensitizer, and a pigment ,
An active energy ray-curable offset ink composition containing 0.1 to 5% of the glycol ether represented by the general formula (1) with respect to the entire composition.
General formula (1)

(In the formula, R1 represents a saturated linear or branched aliphatic hydrocarbon group having 6 to 18 carbon atoms,
R2 represents a saturated linear or branched aliphatic hydrocarbon group having 2 to 3 carbon atoms.
n is 2. ) 2. The active energy ray-curable offset ink composition according to claim 1, wherein the radical polymerizable monomer is a monomer having an ethylenically unsaturated double bond having a weight average molecular weight of 100 to 6000. The active energy ray-curable offset ink composition according to claim 1, further comprising a non-reactive resin. The printed matter formed by printing the active energy ray hardening-type offset ink composition in any one of Claims 1-3 on a base material.