JP6003445B2 - Ink composition - Google Patents

Description

  The present invention relates to a solvent-based gravure ink composition for paper excellent in halftone dot reproducibility and paper substrate versatility.

Conventionally, urethane resins, vinyl acetate resins, acrylic resins, nitrocellulose resins, polyamide resins, chlorinated polyolefin resins, and the like have been used as binder components for gravure inks.
Furthermore, recently, the number of manufacturers that tackle environmental problems has increased, and there is a movement to configure products using materials that are excellent in environmental sanitation. For example, studies have been made not to select toluene as the solvent used in printing ink. Therefore, as a resin suitable for a non-aromatic solvent, one or more kinds selected from nitrocellulose resin, urethane resin, vinyl acetate resin, and acrylic resin are mixed and used as a main resin.
As the base material on which the gravure ink is printed, there are film, paper, aluminum, and the like. Particularly, when the base material is paper, nitrocellulose resin is used as a main component from the viewpoint of adhesion to the paper base material. However, with the nitrocellulose resin alone, when printing ink is overprinted, the printing ink printed later on the previously printed ink film does not show good transferability, which may cause problems in cosmetics. It was. To solve this problem, the overprintability is improved by using an acrylic resin together, but the strength of the ink coating (heat resistance) is reduced, and the adhesion to non-coated paper with no coating layer is reduced. Inferior, versatility to paper base was insufficient. Furthermore, from the viewpoint of environmental hygiene, materials with high safety, low odor and high safety have been demanded.

JP 2008-163231 A JP 2012-111901 A Japanese Patent No. 3993949

An object of the present invention is to provide a printing ink composition having good dot reproducibility and good odor of printed matter in a solvent-based gravure ink composition for paper and excellent in versatility of a paper substrate.

The present invention relates to a printing ink composition containing a colorant, a styrene-maleic acid half ester copolymer (A), a nitrocellulose resin (B), and a solvent, and a styrene-maleic acid half ester copolymer (A). the weight ratio of nitrocellulose resin (B) (solid content ratio) of a styrene - maleic acid half ester copolymer (a): nitrocellulose resin (B) = 50: 50~ 80 : a 20, and a solvent Ri nonaromatic der, the styrene - maleic acid half ester copolymer acid value 185 ~300mgKOH / g, and the glass transition temperature of printing solvent-based gravure rotary for paper is 60 ~ 125 ° C. of (a) The present invention relates to an ink composition.
Furthermore, the present invention relates to a printing ink composition for solvent-borne gravure printing for paper, wherein the solvent contains an ester system and an alcohol system.
Furthermore, this invention relates to the printed matter formed by printing on a paper base material the printing ink composition for solvent-type gravure rotation for paper.

  In the present invention, by using a styrene-maleic acid half ester copolymer and a nitrocellulose resin as an ink binder, the halftone dot reproducibility and the odor of the printed matter are good, and the non-coated paper having no coating layer is provided. However, it is possible to provide a printed matter having excellent adhesiveness.

The colorant used in the present invention includes organic pigments and inorganic pigments, but dyes can also be used in addition to pigments. Specific examples of organic pigments include carmine 6B, lake red C, permanent red 2B, disazo yellow, pyrazolone orange, carmine FB, chromophthal yellow, chromophthal red, phthalocyanine blue, phthalocyanine green, dioxazine violet, quinacridone magenta, quinacridone Examples include red, industron blue, pyrimidine yellow, thioindiobordeaux, thioindigo magenta, perylene red, perinone orange, isoindolinone yellow, aniline black, and daylight fluorescent pigment. Specific examples of inorganic pigments include carbon black, aluminum powder, bronze powder, chrome vermillion, chrome lead, cadmium yellow, cadmium red, ultramarine, cyanide, bengara, yellow iron oxide, iron black, titanium oxide, zinc oxide, etc. Is mentioned. Specific examples of the dye include tartrazine lake, rhodarin 6G lake, Victoria pure blue lake, alkali blue G toner, brilliant green lake and the like, and other coal tars can also be used. The colorants can be used alone or in admixture of two or more for the purpose of adjusting the hue and density. The colorant is used in an amount that ensures the concentration and coloring power of the ink, preferably 4 to 50% by weight based on the total weight of the ink. Even if it does not contain a colorant, the same overprintability can be obtained.

  Examples of the styrene-maleic acid half ester copolymer (A) used in the present invention include esterified resins obtained by partially esterifying a styrene-maleic anhydride copolymer to lower the acid value.

Styrene - maleic acid half ester copolymer (A) has an acid value of from 185 ~300mgKOH / g. If the acid value of the styrene-maleic acid half ester copolymer (A) is less than 65 mgKOH / g, the effect of halftone dot reproducibility tends to be inferior, and if it exceeds 300 mgKOH / g, the solubility in the solvent deteriorates. Problems with storage stability are likely to occur. In addition, an acid value is the mg number of potassium hydroxide required in order to neutralize the acidic group contained in 1g of resin solid content, and is based on JISK0070.

Styrene - glass transition temperature of maleic acid half ester copolymer (A) (Tg) is 60 ~ 125 ° C.. Styrene - the glass transition temperature of maleic acid half ester copolymer (A) is less than 60 ° C., it tends to ink coating film is heat resistance inferior soft, dissolved in the solvent when the glass transition temperature exceeds 145 ° C. As a result, the ink storage stability tends to be problematic.

The glass transition point (Tg) can be measured using a differential scanning calorimeter (DSC measuring device, “DSC-60A” manufactured by Shimadzu Corporation).
The styrene-maleic acid half ester copolymer (A) preferably has a weight average molecular weight of 6,000 to 16,000.

  In addition, the measurement of the weight average molecular weight (Mw) used GPC (gel permeation chromatography) "ShodexGPC System-21" by Showa Denko KK. GPC is liquid chromatography that separates and quantifies substances dissolved in a solvent based on the difference in molecular size. Tetrohydrofuran is used as a solvent, and weight average molecular weight (Mw) is determined in terms of polystyrene.

  As the nitrocellulose resin (B) used in the present invention, an amount of nitrogen of 10 to 13% and an average degree of polymerization of 35 to 90 are preferably used, more preferably an amount of nitrogen of 10.7 to 12.2% and an average degree of polymerization of 45. ~ 70.

  A commercially available product may be used as the nitrocellulose resin (B) used in the present invention, for example, “HIG1 / 2G KCNC, 1 / 4G, 1 / 8G, 1 / 16G” manufactured by KOREA CNC.

In the printing ink of the present invention, when the solid content weight of the styrene-maleic acid half ester copolymer (A) is W1, and the solid content weight of the nitrocellulose resin (B) is W2, the weight ratio (solid content ratio). It is necessary to be within the range of W1: W2 = 50: 50-80 : 20 , and more preferably 60: 40-80: 20. In the range of weight ratio (solid content ratio) W1: W2 = 0: 100 to 49:51, the halftone dot reproducibility tends to be inferior, and in the range of W1: W2 = 91: 9 to 100: 0, the storage stability of ink. The heat resistance and the heat resistance are inferior, and the adhesion to the non-coated paper having no coating layer tends to be inferior.

  As the solvent used in the present invention, hydrocarbon-based, ketone-based, ester-based, and alcohol-based non-aromatic solvents are used. Specifically, hydrocarbons such as methylcyclohexane and ethylcyclohexane, ketones such as acetone, methyl ethyl ketone (MEK) and methyl isobutyl ketone, esters such as ethyl acetate, npropyl acetate and butyl acetate, methanol Alcohol organic solvents such as ethanol, propanol, isopropanol (IPA) and butanol can be used. Considering reduction of the amount of solvent remaining in the ink film after printing, etc., they can be used alone or in combination of two or more.

  Furthermore, in order to improve the halftone dot reproducibility during printing, it is preferable to use a glycol ether solvent. The solvent of the glycol ether solvent is not particularly limited, and examples thereof include ethylene glycol (E.O.) ether and propylene glycol (P.O.) ether. The ethylene glycol (EO) ethers include ethylene glycol monomethyl ether, diethylene glycol monomethyl ether, triethylene glycol monomethyl ether, polyethylene glycol monomethyl ether, ethylene glycol monoisopropyl ether, diethylene glycol monoisopropyl ether, ethylene glycol monobutyl ether, diethylene glycol monobutyl ether. , Triethylene glycol monobutyl ether, ethylene glycol monoisobutyl ether, diethylene glycol monoisobutyl ether, ethylene glycol monohexyl ether, diethylene glycol monohexyl ether, ethylene glycol mono-2-ethylhexyl ether, diethylene glycol mono-2-ethyl ether Sill ether, ethylene glycol monoallyl ether, ethylene glycol monophenyl ether, diethylene glycol monophenyl ether, ethylene glycol monobenzyl ether, diethylene glycol monobenzyl ether. Propylene glycol (PO) ethers include propylene glycol monomethyl ether, dipropylene glycol monomethyl ether, tripropylene glycol monomethyl ether, propylene glycol monopropyl ether, dipropylene glycol monopropyl ether, propylene glycol monobutyl ether, propylene glycol monophenyl Examples include ether, tripropylene glycol monobutyl ether, phenylpropylene glycol, and propylene glycol monomethyl ether acetate. Among these, propylene glycol monomethyl ether, diethylene glycol monoethyl ether, and diethylene glycol monobutyl ether are preferable, and diethylene glycol monoethyl ether is more preferable. As a weight part, it is preferable to use 5 to 25 weight% in a solvent.

The present invention further includes fine-powder silica such as gas phase method silica, wet method silica, organic treatment silica, and alumina treatment silica, polyethylene wax, fatty acid amide wax, antifoaming agent, leveling agent, plasticizer, infrared absorber, Additives such as a pigment dispersant used in combination with an ultraviolet absorber, a flame retardant, and an extender pigment can be used as necessary.
The printing ink composition for solvent-type gravure rotation for paper of the present invention is a gravure for a paper base material having a coating layer such as art paper or coated paper, or a paper base material having no coating layer such as fine paper. Printed matter obtained by printing on a rotary press is used as a packaging material for products such as food.

Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples, but the present invention is not limited to these examples. Unless otherwise specified, all “parts” mean “parts by weight”.

<Adjustment example 1>
<Styrene-maleic acid half ester copolymer varnish>
In a four-necked flask equipped with a stirrer, a thermometer, a reflux condenser and a nitrogen gas introduction tube, a styrene-maleic acid half ester copolymer (SMA 2625, acid value 220 KOH mg / g, glass transition temperature (Tg) 110 ° C. Styrene-maleic acid half ester copolymer having a solid content of 50%, prepared by dissolving 50 parts of Kawa Crude Chemical Co., Ltd.), 25 parts of ethyl acetate and 25 parts of isopropyl alcohol and dissolving in a nitrogen stream at 50 ° C. for 2 hours. A varnish (varnish A1) was obtained.

<Adjustment example 2>
<Styrene-maleic acid half ester copolymer varnish>
In a four-necked flask equipped with a stirrer, a thermometer, a reflux condenser and a nitrogen gas inlet tube, a styrene-maleic acid half ester copolymer (SMA 1440, acid value 185 KOH mg / g, glass transition temperature (Tg) 60 ° C.) Styrene-maleic acid half ester copolymer having a solid content of 50%, prepared by dissolving 50 parts of Kawa Crude Chemical Co., Ltd.), 25 parts of ethyl acetate and 25 parts of isopropyl alcohol and dissolving in a nitrogen stream at 50 ° C. for 2 hours. A varnish (varnish A2) was obtained.

<Adjustment example 3>
<Nitrocellulose varnish>
Nitrocellulose (HIG1 / 8G KCNC, manufactured by KOREA CNC) 72 parts (solid content 70%) was mixed and dissolved in 14 parts of ethyl acetate and 14 parts of isopropyl alcohol to give a test nitrocellulose varnish (varnish) of 50%. B) was obtained.

<Adjustment example 4>
<Cellulose acetate butyrate varnish>
15 parts of cellulose acetate butyrate (CAB381-0.5, manufactured by Eastman Kodak Company) was mixed and dissolved in 43 parts of ethyl acetate and 42 parts of isopropyl alcohol to obtain a cellulose acetate butyrate varnish for test (varnish C) having a solid content of 15%. Obtained.

<Adjustment example 5>
<Rosin varnish>
In a four-necked flask equipped with a stirrer, thermometer, reflux condenser and nitrogen gas inlet tube, acid-modified rosin (Pine Crystal KE-604, manufactured by Arakawa Chemical Industries, Ltd.) with an acid value of 235 KOHmg / g and a softening point of 130 ° C. ), 35 parts of ethyl acetate and 15 parts of isopropyl alcohol were dissolved in a nitrogen stream at 50 ° C. for 2 hours to obtain a test acid-modified rosin varnish (varnish D) having a solid content of 50%.

<Synthesis Example 1>
<Acrylic varnish>
A four-necked flask equipped with a stirrer, thermometer, reflux condenser and nitrogen gas inlet tube was charged with 26 parts of methacrylic acid, 56 parts of methyl methacrylate, 8 parts of acrylic acid, 10 parts of styrene and 200 parts of methyl ethyl ketone, and nitrogen. In an air stream, the temperature was raised to 90 ° C. with stirring, 2 parts of azobisisobutyronitrile was added, the polymerization reaction was carried out for 2 hours, 50 parts separated and purified, 34 parts ethyl acetate and 16 isopropyl alcohol 16 The acrylic varnish for test (varnish E) with a solid content of 50% was obtained.

[Example 1]
Next, yellow pigment (“Pigment Yellow 1450” manufactured by Sanyo Color Co., Ltd.): 10 parts, test nitrocellulose varnish (varnish B): 25 parts, test styrene-maleic acid half ester copolymer varnish (varnish) A1): 25 parts, mixed solvent (n-propyl acetate: ethyl acetate: isopropyl alcohol = 25: 25: 50 (weight ratio): 30 parts, polyethylene wax (manufactured by Mitsui Chemicals, High Wax 220P): 10 parts Were kneaded with an Eiger mill to prepare a yellow ink composition for a base.

  In addition, as an overprinting application, an indigo ink composition was prepared as shown below.

Indigo pigment ("Fastgen Blue FGF-SD" manufactured by DIC Corporation): 10 parts, Test nitrocellulose varnish (varnish B): 25 parts, Test styrene-maleic acid half ester copolymer varnish (varnish A1) ): 25 parts, mixed solvent (n-propyl acetate: ethyl acetate: isopropyl alcohol = 25: 25: 50 (weight ratio): 30 parts, polyethylene wax (manufactured by Mitsui Chemicals, High Wax 220P): 10 parts An indigo ink composition for overprinting was prepared by kneading with an Eiger mill.
Next, the viscosity of these ink compositions was adjusted using a diluting solvent as a viscosity adjusting solvent, with a Zahn Cup No. 3 manufactured by Rouensha Co., Ltd. so that the viscosity was 15 seconds, thereby obtaining ink compositions.
Note that ethyl acetate: isopropyl alcohol = 70: 30 (weight ratio) was used as a dilution solvent.

[Examples 2 , 4 to 6 , Reference Example 3 and Comparative Examples 1 to 5]
About the yellow ink composition for foundation | substrate of Example 2 , 4-6 , Reference Example 3, and Comparative Examples 1-5, it uses the yellow pigment of Example 1, and is the method similar to Example 1 by the mixing | blending shown in Table 1. Prepared. Similarly, indigo ink for overprinting was prepared in the same manner as in Example 1 using the indigo pigment of Example 1 and the formulation shown in Table 1.

[Evaluation item]
Baby printing machine of Iwase Printing Machinery Co., Ltd. using the base yellow ink composition and overprint indigo ink composition obtained in Examples 1 , 2, 4 to 6 , Reference Example 3 and Comparative Examples 1 to 5 The yellow ink composition was overprinted with a conventional 30μ solid plate, and the indigo ink composition was overprinted with a 175 line / inch Helio engraving plate. The paper substrate is art paper with a coating layer, coated paper, and high-quality paper without a coating layer. For overprinting (halftone dot reproducibility), odor, and heat resistance evaluation, use art paper. Evaluation was performed, and adhesion was evaluated using art paper, coated paper, and high-quality paper. The evaluation method and evaluation criteria are shown below. The evaluation results are shown in Table 1.

<Reproducibility of halftone dots>
Table 1 shows the printed parts with a halftone dot percentage of 100% to 3% printed according to the following evaluation criteria, which were printed with a single color of the yellow ink composition and overprinted with the indigo ink composition.
(Evaluation criteria)
◎ ... Percent halftone dot 100% to 3%, very good gradation reproducibility, and no change in halftone dot size at the same halftone dot percentage in single color printing and overprinting.
○ ... Representation of gradation from 100% to 3% halftone dot reproducibility, and no change in halftone dot size in the same halftone dot percentage in single color printing and overprinting.
○ △: Halftone dot percentage 100% to 3%, and gradation is reproducible, and there is a slight change in the halftone dot size in the same halftone dot percentage in single color printing and overprinting.
Δ: Halftone dot percentage 100% to 10%, with gradation reproducibility, and there is a slight change in the halftone dot size at the same halftone dot percentage in monochrome printing and overprinting.
×: Halftone dot percentage: There is no gradation reproducibility of 70% or less, and there is a change in halftone dot size at the same halftone dot percentage in single color printing and overprinting.
Note that the practical level is ◯ Δ or more.

<Adhesion>
The state when cellophane tape was applied to the art paper with the coating layer overprinted with the indigo ink composition, the coated paper, and the high-quality paper printed material without the coating layer, and this was rapidly removed. The evaluation is based on the following evaluation criteria and shown in Table 1.
(Evaluation criteria)
A ... The printed film was not peeled off at all. A ... 80% or more of the printed film remained.
Δ: A printed film of less than 50 to 80% remained.
X: Only a printed film of less than 50% remained.
The practical level is Δ or more.

<Odor of printed matter>
Immediately after printing, the printed matter wrapped in aluminum foil was cut into 0.2 m ² pieces and cut into small pieces and placed in an odor bottle. Sealed and opened after standing at 60 ° C. for 30 minutes, and the odor of the printed matter was evaluated according to the following evaluation criteria.
(Evaluation criteria)
○ ・ ・ ・ No odor, good △ ・ ・ ・ Slight odor,
X: Odor is present and poor, and the practical level is Δ or more.

<Heat resistance>
Match the glossy surface of the aluminum foil (15 microns) to the ink-exposed color surface of the printed matter, and use a thermal gradient heat sealer (manufactured by Toyo Seiki Co., Ltd .; TYPE, HG-100) at 240 ° C. and 2 kg / cm ² × 1 second. Table 1 shows the situation when the aluminum foil is peeled off immediately after heat sealing with the following evaluation criteria.
(Evaluation criteria)
A ... The printed film was not peeled off at all. A ... 80% or more of the printed film remained.
Δ: A printed film of less than 50 to 80% remained.
X: Only a printed film of less than 50% remained.
The practical level is ◯ or higher.

<Ink stability>
The finished ink viscosity of the yellow ink composition and the indigo ink composition and the viscosity after storage at 40 ° C. for 30 days were measured, and the degree of thickening was evaluated according to the following evaluation criteria.
Viscosity was measured with Zaan Cup No. 3 manufactured by Koseisha.
In addition, the presence or absence of precipitates of the ink after finishing and the ink after storage at 40 ° C. for 30 days was evaluated.
(Evaluation criteria)
◎ ... No increase in viscosity and no precipitate ○ ... Increase in viscosity for less than 5 seconds and no precipitate Δ: Increase in viscosity for less than 5 to 10 seconds and / or precipitates are observed, but return by stirring.
X: Increase in viscosity for 10 seconds or more and / or precipitate, and does not return by stirring.
The practical level is Δ or more.

As can be seen from Table 1, Examples 1 , 2, 4 to 6 showed better dot reproducibility and adhesion than Comparative Examples 1 to 5. Furthermore, it was found that Example 6 was particularly excellent in halftone dot reproducibility and adhesion among Examples 1 , 2, 4 to 6.

Claims (5)

In a printing ink composition containing a colorant, a styrene-maleic acid half ester copolymer (A), a nitrocellulose resin (B), and a solvent, the styrene-maleic acid half ester copolymer (A) and the nitrocellulose resin The weight ratio (solid content ratio) to (B) is a styrene-maleic acid half ester copolymer (A): nitrocellulose resin (B) = 50: 50 to 80:20 , and the solvent is non-aromatic. And a styrene-maleic acid half ester copolymer (A) having an acid value of 185 to 300 mgKOH / g and a glass transition temperature of 60 to 125 ° C. Composition. The solvent-type gravure printing ink composition for paper according to claim 1 , wherein the styrene-maleic acid half ester copolymer (A) has a weight average molecular weight of 6,000 to 16,000 . The solvent-containing gravure printing ink composition for paper according to claim 1 or 2, wherein the solvent contains an ester system and an alcohol system. Furthermore, polyethylene wax is contained, The printing ink composition for solvent-type gravure rotation for papers of Claim 1 or 2 characterized by the above-mentioned. A printed matter obtained by printing the printing ink composition for solvent-borne gravure rotation for paper according to any one of claims 1 to 4 on a paper substrate.