JP5565286B2 - Ink composition - Google Patents

Description

  The present invention relates to a solvent-type gravure ink composition for paper having good overprintability.

  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 paper printing inks. When an acrylic resin is used as a main binder for printing ink, printability is good, but the ink film tends to be brittle. Therefore, it is rarely used alone and is generally used in combination with a nitrocellulose resin. Printing inks using acrylic resin and nitrocellulose resin have good printability and adhesiveness (adhesion) for plastic films (for example, polyester film and polystyrene film), and are inexpensive and safe recently. High resin is used. However, when printing ink is overprinted, the phenomenon that the printing ink printed later on the previously printed ink film does not show good transferability and the color tone reproducibility is poor (stains, scratches, reverse trapping, etc.) Occasionally, cosmetic problems may occur.

JP 2008-163231 A Japanese Patent No. 3776264

  An object of the present invention is to provide a printing ink composition having a good ink transfer property in overprinting while maintaining ink film strength in a mixed printing ink composition of an acrylic resin and a nitrocellulose resin.

The first invention of the present invention is a printing ink composition for paper gravure rotary printing for paper containing a colorant, an acrylic resin (A), a nitrocellulose resin (B) and a solvent.
Acrylic resin
Acid value 140-200
And
The weight ratio of acrylic resin (A) to nitrocellulose resin (B) is
Acrylic resin (A): Nitrocellulose resin (B)
= 50: 50-95: 5
And the solvent is
The present invention relates to a solvent-borne gravure printing ink composition for paper, which is non-aromatic.

Furthermore, in the second invention of the present invention, the acrylic resin (A) is
Weight average molecular weight 8000-40000
And glass transition temperature 90-130 ° C
The present invention relates to a printing ink composition for solvent-borne gravure printing for paper according to the first aspect of the invention.

  The third invention of the present invention relates to a printed matter obtained by printing on a paper base material the printing ink composition for solvent-type gravure rotation for paper of the first invention or the second invention.

  The present invention can provide a printed matter having good ink transferability in overprinting and improved color tone reproducibility by using an acrylic resin having an acid value of 140 to 200 and a nitrocellulose resin as an ink binder.

  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 no colorant is contained, the same overprintability can be obtained.

  Further, the present invention further requires additives such as a leveling agent, an antifoaming agent, a wax, a plasticizer, an infrared absorber, an ultraviolet absorber, a flame retardant, and a pigment dispersant when used in combination with an extender pigment. Can be used according to.

  The acrylic resin (A) usable in the present invention can be produced by a conventionally known method, and the production method is not particularly limited. The acrylic resin (A) can be obtained by polymerizing a monomer having a carbon-carbon unsaturated double bond in one molecule in a solvent using a polymerization initiator. Here, the monomer having a carbon-carbon unsaturated double bond in one molecule is (i) (meth) acrylic acid derivative, (ii) aromatic vinyl monomer, (iiii) olefin-based Hydrocarbon monomers, (iv) vinyl ester monomers, (v) vinyl halide monomers, (vi) vinyl ether monomers, and the like.

Examples of (i) (meth) acrylic acid derivatives include (meth) acrylonitrile, (meth) acrylate, methyl (meth) acrylate, butyl (meth) acrylate, ethylhexyl (meth) acrylate, stearyl (meth) acrylate, etc. Examples include alkyl (meth) acrylate and benzyl (meth) acrylate.

(Ii) Examples of aromatic vinyl monomers include styrene, methyl styrene, ethyl styrene, chloro styrene, monofluoromethyl styrene, difluoromethyl styrene, trifluoromethyl styrene and the like in which some hydrogen is fluorine-substituted. And the like.

(Iiii) Examples of olefinic hydrocarbon monomers include ethylene, propylene, butadiene, isobutylene, isoprene, 1,4-pentadiene, and the like. (Iv) Examples of vinyl ester monomers include vinyl acetate.

(V) Examples of vinyl halide monomers include vinyl chloride and vinylidene chloride.

(Vi) vinyl methyl ether etc. are mentioned as an example of a vinyl ether monomer.

Moreover, the monomer which has a carbon-carbon unsaturated double bond in 1 molecule can use the monomer which has a crosslinkable functional group. Examples of the monomer having a functional group include (vii) a monomer having a hydroxyl group, (viii) a monomer having an isocyano group, and (ix) a monomer having an epoxy group.

(Vii) Examples of monomers having a hydroxyl group include 2-hydroxyethyl (meth) acrylate, 1-hydroxypropyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate Polyethylene glycol mono (meth) acrylate, polypropylene glycol mono (meth) acrylate, polytetramethylene glycol mono (meth) acrylate, hydroxystyrene and the like.

(Viii) Examples of monomers having an isocyano group include (meth) acryloyloxyethyl isocyanate, (meth) acryloyloxypropyl isocyanate, 2-hydroxyethyl (meth) acrylate, 4-hydroxybutyl (meth) Examples thereof include those obtained by reacting hydroxyalkyl (meth) acrylate such as acrylate with polyisocyanate such as toluene diisocyanate and isophorone diisocyanate.

(Ix) Examples of the monomer having an epoxy group include glycidyl methacrylate, glycidyl cinnamate, glycidyl allyl ether, glycidyl vinyl ether, vinylcyclohexane monoepoxide, 1,3-butadiene monoepoxide, and the like.

  Depending on the required performance, one of these monomers having a carbon-carbon unsaturated double bond can be used, or a mixture of two or more can be used. Includes styrene, methyl (meth) acrylate, butyl (meth) acrylate, ethylhexyl (meth) acrylate, etc. When styrene is used, the overprinting suitability is good when the styrene monomer composition ratio is 20% by weight or less. There is a tendency.

  The acrylic resin (A) can be obtained by using the polymerization initiator in the presence or absence of a solvent. Examples of the polymerization initiator include ordinary peroxides or azo compounds such as benzoyl peroxide, azoisobutylvalenonitrile, azobisisobutyronitrile, di-t-butyl peroxide, t-butyl perbenzoate, t-butyl. Peroctoate, cumene hydroxy peroxide and the like are used. As the solvent, ethyl acetate, isopropanol, ethanol, methyl ethyl ketone, or the like is used.

  The acid value of the acrylic resin needs to be 140 or more and 200 or less. If it is less than 140, the effect of the overprint suitability is insufficient, and if it exceeds 200, the ink viscosity becomes high, so that the ink dilution rate at the time of printing becomes high and a problem occurs in the overprint suitability. Furthermore, if the acid value exceeds 200, problems arise in water resistance and blocking properties. The polymerization temperature is 50 to 140 ° C, preferably 70 to 140 ° C. The preferred weight average molecular weight of the obtained polymer is 8000 to 40000, more preferably 10,000 to 25,000. If it is less than 8000, the film is brittle and blocking occurs, and if it exceeds 40,000, the resin viscosity increases, which is not preferable. The glass transition temperature (Tg) of the acrylic resin is preferably in the range of 90 to 1300C, more preferably 100 to 120C. If the glass transition temperature is less than 90 ° C, the heat resistance of the printed layer may be reduced or blocking may occur easily. is there.

  As the nitrocellulose resin used in the present invention, a nitrogen content of 10 to 13% by weight and an average degree of polymerization of 35 to 90 are preferably used, more preferably a nitrogen content of 10.7 to 12.2% by weight and an average degree of polymerization. 45-70.

  A commercially available product may be used as the nitrocellulose resin 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, the blending ratio of the acrylic resin and the nitrocellulose resin needs to be in the range of acrylic resin / nitrocellulose resin (weight ratio) = 50/50 to 95/5, and more Preferably it is 60 / 40-90 / 10. If the ratio of the acrylic resin is less than 50/50 (more nitrocellulose resin), the solubility in the solvent may be lowered, and the ink stability may be lowered, and the effect of overprint suitability is insufficient. It is. When the ratio of the acrylic resin is higher than 95/5 (the acrylic resin increases), the blocking resistance, water resistance and the like are insufficient.

  The solvent used in the present invention is preferably a hydrocarbon-based, ketone-based or alcohol-based non-aromatic system. 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.

  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. In the present invention, “part” means “part by weight” unless otherwise specified.

<Preparation of acrylic resin>

<Acrylic resin polymerization example 1>
A four-necked flask equipped with a stirrer, thermometer, reflux condenser and nitrogen gas inlet tube was charged with 10 parts of methacrylic acid, 33 parts of methyl methacrylate, 21 parts of butyl methacrylate, 36 parts of styrene and 200 parts of methyl ethyl ketone, and nitrogen was added. 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 resin varnish (A) having a solid content of 50% by weight, an acid value of 60, a Tg of 110 ° C., and a weight average molecular weight of 4000 was obtained.

<Acrylic resin polymerization example 2>
In a four-necked flask equipped with a stirrer, thermometer, reflux condenser and nitrogen gas inlet tube, 24 parts of methacrylic acid, 60 parts of methyl methacrylate, 6 parts of 2-ethylhexyl acrylate, 10 parts of styrene and 200 parts of methyl ethyl ketone The mixture was heated to 90 ° C. with stirring in a nitrogen stream, and 2 parts of azobisisobutyronitrile was added to carry out the polymerization reaction for 2 hours. 16 parts of isopropyl alcohol was added to obtain an acrylic resin varnish (B) having a solid content of 50% by weight, an acid value of 140, Tg of 90 ° C., and a weight average molecular weight of 10,000.

<Acrylic resin polymerization example 3>
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 resin varnish (C) having a solid content of 50% by weight, an acid value of 200, a Tg of 130 ° C., and a weight average molecular weight of 25000 was obtained.

<Acrylic resin polymerization example 4>
A four-necked flask equipped with a stirrer, thermometer, reflux condenser and nitrogen gas inlet tube was charged with 28 parts of methacrylic acid, 42 parts of methyl methacrylate, 20 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 to carry out a polymerization reaction for 2 hours, and 50 parts separated and purified were mixed with 34 parts ethyl acetate and 16 isopropyl alcohol. The acrylic resin varnish (D) having a solid content of 50% by weight, an acid value of 280, Tg of 120 ° C., and a weight average molecular weight of 50000 was obtained.

<Acrylic resin polymerization example 5>
A four-necked flask equipped with a stirrer, thermometer, reflux condenser and nitrogen gas inlet tube was charged with 24 parts of methacrylic acid, 46 parts of methyl methacrylate, 10 parts of butyl methacrylate, 20 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 to carry out a polymerization reaction for 2 hours, and 50 parts separated and purified were mixed with 34 parts of ethyl acetate and 16 parts of isopropyl alcohol. The acrylic resin varnish (E) having a solid content of 50% by weight, an acid value of 140, Tg of 180 ° C., and a weight average molecular weight of 45,000 was obtained.

<Acrylic resin polymerization example 6>
In a four-necked flask equipped with a stirrer, thermometer, reflux condenser and nitrogen gas inlet tube, 17 parts of methacrylic acid, 11 parts of butacrylic acid, 42 parts of methyl methacrylate, 20 parts of styrene, 10 parts of 2-ethylhexyl acrylate And 200 parts of methyl ethyl ketone were charged, heated to 90 ° C. with stirring under a nitrogen stream, added with 2 parts of azobisisobutyronitrile, polymerized for 2 hours, separated and purified, 50 parts, 34 parts of ethyl acetate and 16 parts of isopropyl alcohol were added to obtain an acrylic resin varnish (F) having a solid content of 50% by weight, an acid value of 165, Tg of 42 ° C., and a weight average molecular weight of 26000.

<Acrylic resin varnish (G), (H), (J)>
As the acrylic resin varnish (G), “Dainal GR-5679” (solid content 45% by weight, acid value 10, Tg 40 ° C., weight average molecular weight 30000) manufactured by Mitsubishi Rayon Co., Ltd. was used.
As the acrylic resin varnish (H), “Dainal BR-107” (solid content 50% by weight, acid value 0, Tg 50 ° C., weight average molecular weight 75000) manufactured by Mitsubishi Rayon Co., Ltd. was used.
As the acrylic resin varnish (J), “Joncrill 682” manufactured by BASF (solid content 50% by weight, acid value 238, Tg 57 ° C., weight average molecular weight 1600) was used.

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

<Measurement method of resin acid value>
The resin acid value is the number of mg of potassium hydroxide required to neutralize the acidic group present in 1 g of resin solids, and is measured according to JIS K0070, and is indicated without a unit in the present invention.

<Measuring method of glass transition point (Tg)>
The glass transition point (Tg) was measured using a differential scanning calorimeter (DSC measuring device).

<Measurement method of weight average molecular weight (Mw)>
The weight average molecular weight (Mw) was evaluated as a polystyrene-equivalent molecular weight using gel permeation chromatography (GPC).

[Example 1]
Next, yellow pigment (“Pigment Yellow 1450” manufactured by Sanyo Color Co., Ltd.): 10 parts, acrylic resin varnish (A): 30 parts, nitrocellulose varnish: 20 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, acrylic resin varnish (B): 30 parts, nitrocellulose varnish: 20 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 an indigo ink composition for overprinting. .
Subsequently, these ink compositions were used as a viscosity adjusting solvent using a diluting solvent. 3 was adjusted to a viscosity of 15 seconds to obtain an ink composition.
In addition, ethyl acetate: isopropyl alcohol = 70: 30 (weight ratio) was used as a dilution solvent.

[Examples 2 to 5 and Comparative Examples 1 to 7]
The undercoat yellow ink compositions of Examples 2 to 5 and Comparative Examples 1 to 7 were the same as those of Example 1. The indigo ink compositions for overprinting of Examples 2 to 5 and Comparative Examples 1 to 7 were prepared in the same manner as in Example 1 by the formulation shown in Table 1. The indigo pigment of the indigo ink composition used for overprinting in Examples 2 to 5 and Comparative Examples 1 to 7 was the same as that in Example 1.

[Evaluation item]
Using the baby printing machine of Iwase Printing Machinery Co., Ltd., the foundation yellow ink composition obtained in Example 1 was printed on special rhombus art paper, and the subsequent overprinting was involved. Used for. The evaluation items were overprintability, ink stability, water resistance, and blocking properties. The evaluation method and evaluation criteria are shown below. The evaluation results are shown in Table 1.

<Applicability for overprinting>
The indigo ink composition was overprinted on the printed material of the yellow ink composition with 175 line / inch helio engraving plate making, and the dot percentage was 100% to 3%. The printed part was evaluated according to the following evaluation criteria. Show.
(Evaluation criteria)
・ ・ ・ ... Good gradation reproducibility from 100% to highlight (3%).
○ ... There is a gradation reproducibility from 100% to highlight (3%).
Δ: There is no gradation reproducibility of the highlight part (3%).
X: There is no gradation reproducibility from the middle part (70%) to the highlight part (3%).
The practical level is ◯ or higher.

<Ink stability>
The ink viscosity at the finish of 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.
The viscosity is Zahn Cup No. 3 was measured.
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)
◎ ・ ・ ・ “Increase in viscosity less than 5 seconds and no precipitate”
○ “Viscosity increase less than 10 seconds and no precipitate”
Δ: “Increased viscosity less than 20 seconds and / or precipitates”
X ... "viscosity increased for 20 seconds or more and / or precipitates are noticeable"
The practical level is Δ or more.

<Water resistance>
Using a Gakushin type anti-friction tester, the printed material on which the indigo ink composition is overprinted is rubbed with hydrous kanakin at a load of 0.2 × 9.8 N (200 g) × 10 times, and the degree of ink removal is evaluated as follows. Evaluation is made based on the criteria and shown in Table 1.
(Evaluation criteria)
○: Ink is not removed Δ: Some ink is removed ×: Significant ink is removed Note that the practical level is Δ or more.

<Blocking property>
The printed surface of the printed material overprinted with the indigo ink composition is overlaid so that the non-printed surface is in contact with each other, a load of 10 kg / cm ² is applied, and aged for 24 hours in an environment of 40 ° C. and 80% RH. The state of ink transfer to the non-printing surface is evaluated according to the following evaluation criteria, and is shown in Table 1.
(Evaluation criteria)
○: The amount of ink transferred to the non-printing surface is 0%.
Δ: The amount of ink transferred to the non-printing surface is 0% to 10%.
X: The amount of ink transferred to the non-printing surface is 10% or more.
The practical level is Δ or more.

  As can be seen from Table 1, Examples 1 to 5 showed better overprintability than Comparative Examples 1 to 7. Furthermore, it was found that the printing ink compositions of Examples 1, 2, and 5 were particularly excellent in overprintability in Examples 1 to 5.

Claims (3)

In a printing ink composition for paper-based gravure printing containing a colorant, an acrylic resin (A), a nitrocellulose resin (B) and a solvent,
Acrylic resin
Acid value 140-200
And
The solid content weight ratio of the acrylic resin (A) and the nitrocellulose resin (B) is
Acrylic resin (A): Nitrocellulose resin (B)
= 50: 50-95: 5
And the solvent is
A solvent-based gravure printing ink composition for paper, which is non-aromatic. The acrylic resin (A) is
Weight average molecular weight 8000-40000
And glass transition temperature 90-130 ° C
The printing ink composition for solvent-type gravure printing for paper according to claim 1.   A printed matter obtained by printing on a paper substrate the solvent-based gravure printing ink composition for paper according to claim 1 or 2.