JPH0737590B2 - Aqueous printing ink composition - Google Patents

Description

TECHNICAL FIELD The present invention relates to a water-based printing ink composition, and in particular, when performing flexographic printing or gravure printing on a material to be printed used for manufacturing paper containers, paper bags and the like. , No swimming, etc.
It is intended to provide an aqueous printing ink composition suitable for obtaining a printed matter of excellent quality.

<Prior Art> In recent years, water-based printing inks have been mainly used for printing packaging materials such as paper containers and paper bags, for example, corrugated board, cartons, sachets, heavy bags, etc., and are printed by a flexo or gravure method. In printing in these packaging fields as well, there is an increasing demand for improved print quality, higher quality, and beauty, and not only printing inks but also printing plates and printing methods for printing machines have been improved.

First, in printing inks, the water-based resin serving as the binder has been mainly improved. From aqueous solutions of shellac, casein, and rosin maleic acid-based natural or modified resins, recently, acrylic resins, styrene / acrylic resins, and styrene / maleic resins have been used. Alkaline aqueous solutions of resins and various copolymer resins such as styrene / acrylic / maleic resins have come to be used, and various resin emulsions such as acrylic and styrene resins have also come to be used.

In the field of printing plates, especially flexographic printing plates, hand engraving,
From a molding plate to a photosensitive resin relief plate, fine image reproduction or multicolor overprinting using a halftone plate has come to be performed.

In the field of printing machines, especially flexographic printing machines, the use of anilox rollers or doctor blades having a large number of lines has come to be used, and accurate adjustment of ink amount has come to be carried out.

Also, in the field of corrugated board printing, instead of printing on corrugated cardboard that is pasted with a corrugator machine,
There is also a method of preventing deterioration of print quality due to the step by performing liner printing in advance on a liner-shaped corrugated fiberboard paper, performing liner printing, and then pasting with a corrugator machine to obtain corrugated cardboard printed matter. ing.
Further, as paper to be printed used for printing, high-quality paper such as kraft paper, medium-quality paper, and coated paper has come to be used.

<Problems to be Solved by the Invention> As described above, various improvements have been made in printing with a water-based printing ink. However, due to a change in the printing medium or a change in the printing method associated with higher quality and beauty, In terms of print quality, which has not been a problem so far, that is, color development of water-based ink, uniformity of coating film, or swimming (refers to a satin-like unevenness on the surface of printed matter caused by insufficient leveling or transferability of ink). However, the problem of being inferior to lithographic printing has been raised. When such a swimming phenomenon occurs, the print quality is remarkably deteriorated, and in multicolor printing, a problem of partial color reproducibility or color unevenness occurs.

The present invention is intended to solve such a problem.

<Means for Solving Problems> That is, according to the present invention, a water-based printing ink composition containing a paper as a material to be printed contains a compound represented by the following general formula in a specific range. Is to solve.

General formula Hereinafter, the aqueous printing ink composition according to the present invention will be described in detail.

The aqueous printing ink composition according to the present invention is mainly composed of a colorant and an aqueous binder.

As the colorant, dyes, inorganic, organic and extender pigments that have been commonly used in water-based inks can be used.

As the aqueous binder, an alkali-soluble type resin binder or an aqueous dispersion type resin binder can be used. As the alkali-soluble resin, a resin having an acid value in the range of 30 to 400 can be used. Specifically, shellac, rosin-modified maleic acid, etc. can be used, but various acrylic monomers such as (meth) acrylic acid esters, (meth) acrylic acid, (meth) acrylamides, (meth) acrylonitrile, styrene, Styrene-based monomers such as α-methylstyrene and vinyltoluene, maleic acid, maleic acid half-esters, maleic acid diesters, and
Copolymer resins obtained by a conventional method from various vinyl monomers such as fatty acid vinyl esters such as vinyl acetate and esters of other unsaturated carboxylic acids can be used. It is necessary for the softening point of these copolymer resins to be 40 ° C. or higher and the molecular weight to be in the range of 5,000 to 100,000 from the viewpoint of fluidity and stability of the ink.

The water-dispersible resin used in combination with the alkali-soluble resin binder may be an acrylic resin, a styrene resin, or any of the above vinyl monomers emulsion-polymerized.

In addition to the above colorants and aqueous binders, various additives can be used if necessary, and examples include defoaming agents, water-miscible solvents, lubricants, plasticizers and the like.

The compound added to the water-based printing ink composition consisting of the above-mentioned components, in the general formula, n is 1 to 4
Is required, and when n is 5 or more,
Solubility in water-based printing ink is improved, and the desired effect cannot be obtained. On the other hand, when R ₁ and R _{2 each} have less than 4 carbon atoms, the solubility is similarly increased, and the desired effect cannot be obtained. When the carbon number exceeds 8, they cannot be mixed in the ink and are separated. , Which hinders the stability of the ink.

Specific examples of the compound represented by the general formula include ethylene glycol dibutyl ether, ethylene glycol butylhexyl ether, propylene glycol dibutyl ether, propylene glycol stilpentyl ether, diethylene glycol dibutyl ether, diethylene glycol butylhexyl ether, dipropylene glycol dibutyl ether. , Dipropylene glycol butyl pentyl ether, triethylene glycol dibutyl ether, triethylene glycol dihexyl ether, tripropylene glycol dibutyl ether, tetraethylene glycol dibutyl ether, tetrapropylene glycol dihexyl ether, and the like.

The addition amount of these compounds, it is necessary to adjust depending on the type of compound, with respect to the total amount of the aqueous printing ink, 0.1 to 10.0 wt%, more preferably 0.1 to 5.0
It is possible to add and mix it in the range of wt%. If the amount added is outside the above range, that is, less than 0.1% by weight, the desired effect of preventing swimming cannot be obtained, or if it exceeds 10.0% by weight, it becomes difficult to mix in the ink, and the stability of the ink is stabilized. Not only does this impair the sex, but the effect is not obtained even if added further.

The aqueous printing ink composition according to the present invention can be produced by mixing a colorant and, if necessary, an additive in an aqueous binder, according to a conventional method. Regarding the addition of the compound represented by the general formula, the compound may be added at the production stage of the ink or after the addition at the ink preparation stage.

<Operation> The compound represented by the general formula, which is added and mixed in the aqueous printing ink composition according to the present invention, has extremely low solubility in water and is in the range of 0.1 to 5% by weight.

Incorporation of these compounds into the water-based printing ink composition in a specific range has the effect of significantly lowering the surface tension of the ink, which may solve problems such as swimming.

Hereinafter, the present invention will be described more specifically with reference to Examples, but the present invention is not limited thereto.

<Examples> Varnish Production Example 1. Styrene / acrylic copolymer resin (Jyonkryl 678, manufactured by Nippon Jyonson Co., Ltd.) (acid value 200, softening point 146 ° C) 25 parts by weight, ammonia water (28%) 5 parts by weight, water Varnish 1 is manufactured by mixing 70 parts by weight and dissolving the resin.

Varnish Production Example 2. Using 27 parts by weight of styrene, 22 parts by weight of maleic acid, 1 part by weight of benzoyl peroxide, and 50 parts by weight of toluene, solution polymerization was carried out according to a conventional method, and then the solvent was removed to obtain an acid value of 233. Was obtained. 25 parts by weight of the resin, ammonia water (28%) 5
By mixing 70 parts by weight of water and 70 parts by weight of water, Varnish 2 was obtained.

Examples 1-10 15 parts by weight of pigment (phthalocyanine blue), 1,65 parts by weight of varnish, 0.3 parts by weight of antifoaming agent (silicone antifoaming agent), 10 parts by weight of water, and 2.0 parts of the compounds shown in Table 1 respectively. By mixing parts by weight, an aqueous ink is produced using an attritor according to a conventional method. Let each ink be Inks 1-10.

Examples 11 to 13 In the ink composition of Example 2, the varnish 1 was replaced as shown in Table 2 to prepare water-based inks.
11 to 13.

Note 1) As the varnish 3, an acrylic water-based emulsion (John Krill 74J, manufactured by Nippon Johnson Co., Ltd.), a solid content of 45% by weight, and a viscosity of 400 cps / 25 ° C are used.

Comparative Examples 1 to 10 The compounds of Example 1 were changed to the solvents shown in Table 3, and the same water-based inks were produced.

Examples 14 to 15 and Comparative Examples 11 to 12 Among the formulations of Example 2, the addition amount of diethylene glycol dibutyl ether was changed according to Table 4, and the same water-based ink was produced. The respective inks are inks 14-15 and comparative inks 11-12.

Comparative test Using the inks 1 to 15 and the comparative inks 1 to 12 obtained in Examples 1 to 15 and Comparative Examples 1 to 12, printing was performed on a coated paper with a gravure printing machine to evaluate the print quality. Further, each of the obtained inks was evaluated for storage stability, drying property and the like. The evaluation results are shown in Table-5.

In addition, yellow inks each having the same composition as the above ink and using disazo yellow as a colorant were manufactured, and the above blue ink was overprinted on the solid part of the yellow ink to evaluate color reproducibility.

Evaluation method Presence / absence of swimming: The solid part with a depth of 30μ in the gravure plate was visually inspected for the presence / absence of swimming, and a uniform coating film was evaluated as ○, a swimming film was recognized as △, and a swimming pattern was marked as ×. .

On-machine stability: Check the printed matter 60 minutes after the start of printing for the occurrence of streaks due to poor doctor cutting. ○ If there is no problem at all, △ indicates that there is a tendency for streaking, and if there is streaking. It was evaluated as x.

Color reproducibility: The color reproducibility and hue unevenness of the overlapped portion in the overprinting were examined, and the target uniform hue was evaluated as ◯, the hue unevenness was recognized as Δ, and the unevenness was marked as x.

Dryability: Each ink is spread on a coated paper with a bar coater, and the dryness 5 seconds after the spread is examined by touching with a finger,
It was evaluated as ◯, Δ, or × depending on the dry state.

Storage stability: The color ink was left in a thermostatic chamber at a temperature of 40 ° C for 1 week, and the ratio of change in viscosity was measured.

A viscosity increase of 120% or less compared to the viscosity at the time of production was evaluated as ◯, a viscosity of less than 200% was evaluated as Δ, 200% or more, or a gelled product was evaluated as x.

<Effects of the Invention> As described specifically above with reference to Examples, in the water-based printing ink composition in which a predetermined amount of the compound specified in the present invention is added and mixed, a printing material having poor penetrability of the water-based ink is printed. Even if a body such as coated paper is used, a high-quality printed matter having a uniform film which does not cause swimming development can be obtained.

Claims (2)

[Claims] 1. An aqueous printing ink composition mainly composed of a colorant and an aqueous binder, wherein a compound represented by the following general formula is added to the aqueous printing ink composition in an amount of 0.1.
A water-based printing ink composition, characterized in that it is contained in an amount of up to 10% by weight. General formula 2. The aqueous binder is an aqueous solution of an alkali-soluble resin selected from a styrene / acryl copolymer resin, a styrene / malein copolymer resin or a styrene / malein / acrylic copolymer resin. A water-based printing ink composition according to claim 1.