JP2011122023A - Aqueous pigment dispersion and aqueous printing ink composition comprising the same - Google Patents

Abstract

An aqueous pigment dispersion having good pigment dispersibility over various pigments and capable of high concentration, having high gloss and clear color, and a good aqueous property such as drying property and heat resistance using the same. A printing ink composition is provided.
SOLUTION: A styrene monomer, a styrene monomer, and 3 to 15% by mass of an α-olefin monomer in all components constituting a styrene / α-olefin / maleic acid copolymer resin. And a radically polymerizable monomer having a maleic monomer as a main component, and is obtained by a general formula (1) based on a reaction of the maleic monomer with an anhydride ring or a carboxyl group. A styrene / α-olefin / maleic acid copolymer resin having a specific acid value and a weight average molecular weight, which contains at least one group represented by the group represented by formula (2) An aqueous pigment dispersion containing a specific ratio with respect to 100 parts by mass.
_{-COO- (C 2 H 4 O)} p (C 3 H 6 O) qR1 general formula (1)
-COO-R2 Formula (2)
[Selection figure] None

Description

  The present invention relates to an aqueous pigment dispersion and an aqueous printing ink composition using the same. More specifically, water-based printing with good dispersibility across various pigments and high concentration, and excellent printability such as drying, heat resistance, and overprintability when used in printing ink compositions. The present invention relates to an aqueous pigment dispersion that provides an ink composition.

  From the viewpoints of environmental problems, disaster prevention, and resource saving, the use of organic solvents and water removal have long been studied in the field of printing inks and paints.

  For example, in the field of printing inks, liquid inks used in flexo and gravure printing methods have been the subject of the above studies for a long time. Among them, the inks in the field where papers such as corrugated cardboards and paper bags were used as the adherends quickly became water-based.

  This is because the paper is porous and the surface is easy to get wet with water, so that the water penetrates and the ink dries quickly, and printing unevenness is unlikely to occur. It was because it was suitable for conversion.

  However, in recent years, when the purpose of printing on packaging containers is not limited to just displaying contents, it is required to have high gloss and clear color for the ink used for it. It has become so.

  In addition, more and more complicated patterns overlap, and when water-repellent liner paper with high water repellency against water wetting, which is a weak point of paper, is used, the suitability for overprinting between inks, There is also a need for printability with water-repellent paper (water repellent paper suitability).

  As a means to improve these ink performances, in order to give high gloss and clear colors, it is indispensable that the binder resin is well wetted on the pigment surface and the pigment is more finely dispersed. The surface of the organic pigment is hydrophobic, and there is a problem that an ordinary binder resin such as an acrylic used in an aqueous system is difficult to wet.

  In order to solve this problem, the present applicant has proposed an α-olefin / maleic acid copolymer having a specific alkylene glycol monoalkyl group in the molecule as a pigment dispersing resin (for example, patents). Reference 1). By using this pigment-dispersing resin, it is possible to increase the concentration over various pigments, and when used in an aqueous printing ink composition, the suitability for overprinting, the suitability for riding on water-repellent paper, and the like are improved.

  However, such an α-olefin / maleic acid copolymer has a low glass transition temperature. Therefore, when it is made into an ink, it has adhesiveness even after moisture and the like are evaporated and dried. With such an adhesive ink, when paper is wound or stacked as a printing medium after printing, the printing surface comes into contact with the back surface of the printing medium and stains easily occur. In addition, high-speed printing is required for streamlining printing, and the time until the printed surface comes into contact with the back surface of the printing medium is shortened. If the ink is undried and wet at this time, the occurrence of smearing is promoted.

  Furthermore, recently, for the purpose of more decorative printing, printing on liner paper before becoming corrugated cardboard, and pre-print printing method to later use corrugated cardboard has been increasing. Passes through a hot platen to speed up the drying of the glue. At this time, the ink using the α-olefin / maleic acid copolymer has low heat resistance, so that the ink adheres to the hot plate and the printing surface is stained.

  Therefore, there was room for further improvement such as reduction of the adhesiveness of the film, improvement of drying property, improvement of heat resistance, etc., while maintaining the good performance of the α-olefin / maleic acid copolymer.

Japanese Patent Laid-Open No. 11-246813

  Accordingly, an aqueous pigment dispersion having good pigment dispersibility and high concentration over the various pigments of the present invention, having high gloss and clear colors, and good drying properties, heat resistance, etc. An aqueous printing ink composition is provided.

  As a result of intensive studies to solve the above problems, the present inventors have solved all of the above problems by using a specific styrene / α-olefin / maleic acid resin as a pigment dispersion resin. The present invention has been found and the present invention has been completed.

  The concept of the present invention is as follows.

  By using an α-olefin / maleic acid copolymer (resin) that has a specific alkylene glycol monoalkyl group in the molecule and has a high pigment dispersion effect, the present applicant can increase the concentration over various pigments. For water-based printing ink compositions, a technique for improving the overprinting suitability, water-repellent paper riding suitability, etc. has been proposed previously. In the present invention, while maintaining the performance of the α-olefin / maleic acid copolymer, the drying property includes an ink for the purpose of improving drying property, reducing adhesiveness, and improving heat resistance. Attempts were made to solve the problem by improving the separation rate from liquid components such as aqueous media when the ink was printed, and increasing the glass transition temperature (Tg) for tackiness and heat resistance.

  First, in order to improve the drying property, the amount of the hydrophobic component is increased. On the other hand, in order to improve the adhesion and heat resistance, the amount of the α-olefin monomer having a low Tg even with the hydrophobic component is minimized. In view of the above, the first feature is to introduce a hydrophobic monomer having a high Tg as a copolymerization component.

  From this viewpoint, the amount of the α-olefin monomer is in the range of 3 to 15% by mass in the total components constituting the styrene monomer and the styrene / α-olefin / maleic acid copolymer resin. A new styrene monomer having a high Tg was added to the copolymerization component. Thereby, the Tg of the obtained copolymer resin can be increased without reducing the amount of the hydrophobic component, and the problems of ink drying property, adhesion and heat resistance can be solved.

Furthermore, in the present invention, in order to adjust the change in surface tension (change to the higher side) during ink formation due to the weight loss of the α-olefin monomer, it originates from the reaction with the carboxyl group of maleic acid. The second feature is to introduce a group represented by the following general formula (2). Due to this feature, the surface tension at the time of inking is lowered, and the extended wetting of the ink on the paper surface is promoted, so that good print quality can be obtained.
-COO-R2 Formula (2)
[Wherein R2 is a hydrocarbon group having 1 to 8 carbon atoms. ]

  As described above, while maintaining the performance of the previously developed α-olefin / maleic acid copolymer from the first feature and the second feature, the drying property at the time of inking is improved, the tackiness is reduced, Improvement of heat resistance was realized, and all the problems were solved.

That is, the present invention relates to an aqueous pigment dispersion in which a pigment is dispersed in water using a pigment dispersing resin, and the styrene monomer, styrene / α-olefin / maleic acid copolymer is used as the pigment dispersing resin. Obtained by copolymerizing α-olefin monomer in the range of 3 to 15% by mass and radically polymerizable monomer having maleic acid monomer as the main component in the total constituent components of the combined resin. And a group represented by the following general formula (1) and a group represented by the following general formula (2) based on the reaction with the anhydride ring or carboxyl group of the maleic acid monomer at least 1 in the molecule. Contains a styrene / α-olefin / maleic acid copolymer resin having an acid value of 90 to 240 mg KOH / g and a mass average molecular weight of 2000 to 40000 in a proportion of 3 to 20 parts by mass with respect to 100 parts by mass of the pigment. You It relates to an aqueous pigment dispersion according to claim.
_{-COO- (C 2 H 4 O)} p (C 3 H 6 O) qR1 general formula (1)
(Where R1 is H or an alkyl group having 1 to 8 carbon atoms, p and q are integers of 0 or more, p + q ≧ 1, and the formula weight of the general formula (1) is 494 or less. The number of combinations that satisfy the conditions
-COO-R2 Formula (2)
(Here, R2 is a hydrocarbon group having 1 to 8 carbon atoms.)

  The group represented by the general formula (1) is p = 1 to 3, q = 0, R1 is an alkyl group having 1 to 4 carbon atoms, and the group represented by the general formula (2) is R2 It is preferable to contain a styrene / α-olefin / maleic acid copolymer resin which is an alkyl group having 1 to 4 carbon atoms.

  The present invention also relates to an aqueous printing ink composition comprising the aqueous pigment dispersion.

  According to the aqueous pigment dispersion of the present invention, the pigment dispersibility is excellent over various types of pigments, the concentration can be increased, and the aqueous pigment dispersion having high gloss and clear color, and the drying property using the aqueous pigment dispersion are used. A water-based printing ink composition having good heat resistance and the like can be provided.

  The present invention will be described in detail below.

  First, the aqueous pigment dispersion of the present invention will be described.

  As the pigment constituting the aqueous pigment dispersion of the present invention, various inorganic pigments and organic pigments that can be generally used in aqueous printing inks and paints can be used.

  Specific examples of the inorganic pigment include colored pigments such as titanium oxide, bengara, antimony red, cadmium yellow, cobalt blue, bitumen, ultramarine, carbon black, graphite, and calcium carbonate, kaolin, clay, barium sulfate, aluminum hydroxide. And extender pigments such as talc. Furthermore, examples of the organic pigment include soluble azo pigments, insoluble azo pigments, azo lake pigments, condensed azo pigments, copper phthalocyanine pigments, and condensed polycyclic pigments. In the aqueous pigment dispersion of the present invention, the content of these pigments is usually about 3 to 60% by mass, and can be satisfactorily dispersed in water using the pigment dispersing resin described below.

Next, as the pigment dispersion resin used for dispersing the pigment constituting the aqueous pigment dispersion of the present invention, styrene monomers, α-olefin monomers in a specific amount range, and maleic acid are used. It is obtained by copolymerizing a radical polymerizable monomer having a main monomer as a main component, and is represented by the following general formula (1) based on a reaction with an anhydride ring or a carboxyl group of a maleic acid monomer. And a styrene / α-olefin / maleic acid copolymer resin containing at least one group represented by the following general formula (2) in the molecule. It is dissolved in water in the presence and used as a water-soluble resin varnish.
_{-COO- (C 2 H 4 O)} p (C 3 H 6 O) qR1 general formula (1)

Here, R1 is H or an alkyl group having 1 to 8 carbon atoms, p and q are integers of 0 or more, p + q ≧ 1, and the formula weight of the general formula (1) is 494 or less. It is a combination of numbers that satisfy the conditions.
-COO-R2 Formula (2)

  Here, R2 is a hydrocarbon group having 1 to 8 carbon atoms.

  As the styrene monomer for synthesizing the styrene / α-olefin / maleic acid copolymer, styrene, α-methylstyrene, vinyltoluene and derivatives thereof can be used. This styrenic monomer is used to improve the drying and heat resistance of the aqueous printing ink composition.

  In addition, as the α-olefin for synthesizing the styrene / α-olefin / maleic acid-based copolymer, a liquid having 6 to 40 carbon atoms in the reaction can be used. For example, 1-hexene, 1-hexene, Heptene, 1-octene, 1-nonene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicocene, 1-docosene, 1-tetracocene, 1-octacocene, 1-triacontene , 1-dotria contentene, 1-tetratria contentene, 1-hexatria contentene, 1-octatria contentene and the like.

  Among them, those having a low molecular weight are advantageous for the dispersibility of a pigment having a hydrophilic surface, and those having a high molecular weight are advantageous for the dispersibility of a pigment having a hydrophobic surface. The dispersibility can be adjusted according to the characteristics of the pigment surface. However, if it has an excessive molecular weight, it will be difficult to maintain sufficient water solubility of the copolymer, so an α-olefin having about 8 to 20 carbon atoms is desirable.

  In addition, content in the copolymer of an alpha olefin is the range of 3-15 mass%.

  When the content of the α-olefin copolymer is less than 3% by mass, the pigment dispersibility is lowered, and when used in an aqueous printing ink composition, the overprintability and the water-repellent paper riding tendency tend to be lowered. It is in. On the other hand, when the content in the α-olefin copolymer is more than 15% by mass, the adhesiveness becomes high when inking, and the heat resistance and the like tend to decrease.

  As maleic acid for synthesizing the styrene / α-olefin / maleic acid copolymer, maleic acid and maleic anhydride can be used.

  In addition, for the synthesis of this styrene / α-olefin / maleic acid copolymer, an acrylic monomer that can be copolymerized with the above-described constituent materials is used if necessary, as long as the performance does not deteriorate. For example, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate , (Meth) acrylic acid alkyl ester compounds such as stearyl (meth) acrylate, (meth) acrylic acid ester compounds containing aromatic rings such as benzyl (meth) acrylate and naphthyl (meth) acrylate, 2-hydroxyethyl (meth) Acrylate, 2-hydroxypropyl (meta Acrylate, 3-hydroxypropyl (meth) acrylate such as (meth) hydroxyalkyl acrylate alkyl ester compound can be exemplified.

  In addition, it is preferable that content in the styrene / α-olefin / maleic acid copolymer of the acrylic monomer copolymerizable with the constituent material is 15% by mass or less.

  The copolymer of the present invention is an acrylic monomer that can be copolymerized with the above styrene monomer, the above α-olefin, (anhydrous) maleic acid or a maleic ester compound, and, if necessary, the above constituent materials. It is produced by the reaction.

Then, final copolymerization is achieved by ring opening reaction of an anhydride group or esterification reaction with a carboxyl group by a compound represented by the following general formula (3) and a compound represented by the following general formula (4). In the coalescence, at least one of the groups represented by the general formula (1) and the general formula (2) has a structure bonded to the main chain by an ester bond.
_{HO- (C 2 H 4 O)} p (C 3 H 6 O) qR1 (3)

Here, R1, p, and q have the same definitions as in general formula (1). Further, the C ₂ H ₄ O group and the C ₃ H ₆ O group may be random or block.
HO-R2 (4)

  Here, R2 has the same definition as in the general formula (2).

  Specifically, as the compound represented by the general formula (3), (poly) ethylene glycol, (poly) propylene glycol and monoalkyl ether compounds having up to 8 carbon atoms in the molecular weight range up to 467, A hydroxyl group-containing compound such as a copolymer of ethylene oxide and propylene oxide using ethylene glycol or propylene glycol as an initiator and a monoalkyl ether compound having up to 8 carbon atoms thereof can be used.

  Among these, in general formula (2), p = 1 to 3 and q = 0, and R1 is 1 to 1 carbon atoms in that it has a good dispersibility effect on both hydrophilic and hydrophobic surfaces. And an alkyl group having 1 to 4 carbon atoms in the general formula (3) can be suitably used.

  In addition, when the molecular weight of the compound represented by the general formula (3) is larger than 467, that is, when the formula weight of the general formula (1) is larger than 494, a high esterification rate is maintained while maintaining sufficient water solubility. There is a problem that it is difficult to obtain a copolymer of the above and pigment dispersibility is lowered. On the other hand, when R1 has more than 8 carbon atoms, the dispersibility of the pigment having a hydrophilic surface is poor, which is not preferable. Further, when the number of carbon atoms in R2 of the compound represented by the general formula (4) exceeds 8, the dispersibility of the pigment having a hydrophilic surface tends to be poor, which is not preferable.

  Copolymerization reaction of styrene monomer, α-olefin, maleic acid monomer and acrylic monomer that can be copolymerized with the above-mentioned constituent materials as required, and hydroxyl group containing For the esterification reaction with the compound, a normal method can be used, but the esterification reaction is an acrylic copolymerizable with the styrenic monomer, α-olefin, (anhydrous) maleic acid and, if necessary, the above constituent materials. It may be before or after the radical polymerization reaction of the system monomer. That is, (maleic anhydride) is first reacted with the hydroxyl group-containing compound to obtain a maleate ester monomer, then copolymerized with a styrenic monomer and an α-olefin, and if necessary, the above constituent materials An acrylic monomer that can be copolymerized with styrene / α-olefin / (anhydrous) maleic acid copolymer may be synthesized and then reacted with the hydroxyl group-containing compound for esterification. In particular, from the viewpoint of reactivity, the esterification reaction is a radical polymerization of a styrene monomer, an α-olefin, (anhydrous) maleic acid, and an acrylic monomer copolymerizable with the above-described constituent materials as necessary. After the reaction is preferred.

  If the esterification reaction is performed first, deesterification is performed when the styrene monomer and α-olefin are copolymerized later with an acrylic monomer copolymerizable with the above-described constituent materials as necessary. On the other hand, when the esterification is carried out later, maleic anhydride is preferably used as a copolymer component from the viewpoint of increasing the esterification reactivity. In addition, when a compound having two hydroxyl groups is used as a hydroxyl group-containing component, the hydroxyl group-containing component is preliminarily larger than 2 mol with respect to 1 mol of maleic anhydride so as not to cause a crosslinking reaction. It is preferable to use after obtaining a maleic acid monoester compound reacted for a long time at a low temperature.

  Furthermore, the styrene / α-olefin / maleic acid copolymer of the present invention has at least one group represented by the general formula (1) and one group represented by the general formula (2) in one molecule. The reaction amount of the styrene / α-olefin, (anhydrous) maleic acid and the hydroxyl group-containing compound of the general formula (3) and the general formula (4) is adjusted.

  A known method can be used to produce the styrene / α-olefin / maleic acid copolymer of the present invention using the above reaction materials. For example, copolymerization of a styrene monomer, an α-olefin, a maleic acid compound, and an acrylic monomer copolymerizable with the above-described constituent materials as necessary is acetone, methyl ethyl ketone, benzene, toluene, ethyl acetate. About 40 by using a radical polymerization catalyst such as an organic peroxide such as benzoyl peroxide and cumene hydroperoxide and an azobis compound such as α, α′-azobisisobutyronitrile in an inert solvent such as It is carried out at a reaction temperature of ˜170 ° C.

  The ring opening reaction of the maleic anhydride group by the hydroxyl group-containing compounds of the general formula (3) and the general formula (4) is performed in a solventless system or in an inert solvent in which the hydroxyl group-containing compound is dissolved. The heating can be performed at about 180 ° C.

  The styrene / α-olefin / maleic acid copolymer of the present invention obtained as described above is further dissolved in water and used as an aqueous resin varnish in the presence of a basic compound. Examples of the basic compound include inorganic basic compounds such as sodium hydroxide, potassium hydroxide and ammonium hydroxide, and organic basic compounds such as triethylamine, monoethanolamine and triethanolamine. The amount of these basic compounds used may be in a range where the good solubility and drying property of the copolymer can be maintained, but in particular 80 to 120 with respect to the amount necessary to neutralize the copolymer. About mol% is an appropriate amount.

  The acid value of the styrene / α-olefin / maleic acid copolymer of the present invention is 90 to 240 mgKOH / g, preferably 100 to 180 mgKOH / g, and the mass average molecular weight is 2000 to 40000, preferably 6000 to 12000. If the acid value of the copolymer is less than 90 mgKOH / g, the solubility in water is lowered, while if it exceeds 240 mgKOH / g, the water resistance of the printed matter is undesirably lowered. On the other hand, when the weight average molecular weight of the copolymer is lower than 2000, the effect of finely dispersing the pigment of the copolymer is lowered. On the other hand, when it is higher than 40000, the viscosity stability over time is unfavorably deteriorated.

  Next, a method for producing the aqueous pigment dispersion of the present invention using a pigment and a pigment dispersing resin will be described.

  Usually, in the field of inks and paints, a method is used in which a pigment-dispersing resin water-soluble varnish and a pigment are stirred and mixed, and then kneaded by various dispersing machines such as a bead mill, a ball mill, and an attritor. The amount of the dispersing resin necessary for the treatment is 3 to 100 parts by mass, preferably about 5 to 20 parts by mass with respect to 100 parts by mass of the pigment.

  Here, of course, pigment dispersion can also be carried out as the styrene / α-olefin / maleic acid copolymer specified in the present invention for the total amount of the pigment dispersing resin used, but the styrene / α-olefin / The amount of the maleic acid copolymer is at least 3 parts by mass with respect to 100 parts by mass of the pigment, and the remaining amount of resin necessary for the dispersion can be used in combination with a known aqueous resin used in ordinary inks and paints. It is possible to obtain an aqueous pigment dispersion having good properties and sufficiently high storage stability and gloss. In addition, the aqueous printing ink composition using the obtained aqueous pigment dispersion has improved heat resistance and drying properties as described later.

  Furthermore, in order to stabilize the dispersion of the pigment, a method of obtaining a water-based pigment dispersion by adding a predetermined amount of resin or water called stretching formula is generally used. The water-based pigment dispersion of the present invention is used as a corrugated cardboard printing ink. When used in the composition, it is advantageous to preliminarily contain a large amount of the styrene / α-olefin / maleic acid copolymer specified in the present invention in consideration of drying properties, heat resistance, and suitability for riding on water-repellent paper. It is.

  The water-based pigment dispersion of the present invention can be used as a material for water-based printing inks and paints, and if necessary, other binder resins, organic solvents and various additives are added to produce water-based printing ink compositions and paints. Can do.

  Here, in particular, other binder resins used in the aqueous printing ink composition include shellac resins, acrylic resins, styrene-acrylic resins, styrene-maleic resins, styrene-acrylic-maleic acids that are generally used in aqueous printing inks. Resin, polyurethane resin, polyester resin, polyamide resin, and the like. In the presence of a water-soluble resin varnish in which a carboxyl group is introduced into the molecule and dissolved in water in the presence of a basic compound, or in the presence of an emulsifier As a water-dispersible resin varnish dispersed in water, it is added to the aqueous pigment dispersion. In the case where the styrene / α-olefin / maleic acid copolymer of the present invention has a low acid value, an acrylic resin, a styrene / acrylic resin, a styrene / maleic acid resin, a styrene / acrylic malein is used from the viewpoint of compatibility. It is preferably used in an ink system using an acid resin.

  Examples of the organic solvent that can be used in the aqueous printing ink composition include lower alcohols such as methanol, ethanol, and propanol, and water-miscible solvents such as ethylene glycol, propylene glycol, and alkyl ethers thereof. Furthermore, use of a crosslinking agent, an antiblocking agent, an antifoaming agent, a film forming aid, a rebelinder agent, a transferability improving agent, etc. is optional as an additive.

The preferred composition of the aqueous printing ink composition of the present invention is as follows.

Component Mass%
Pigment 1-50
Styrene / α-olein / maleic acid copolymer of the present invention 0.03-10
Other pigment dispersion resins 0-20
Binder resin 0-40
30-30 water
Water miscible organic solvent 0-30

  The aqueous printing ink composition obtained as described above can be printed on an adherend such as paper or plastic film by flexographic or gravure printing. Specifically, examples of the type of paper used as the adherend include jute paper, craft paper, water-repellent paper, and various coated papers. Examples of the plastic film include polyethylene, stretched and unstretched polypropylene, polyester, Examples include nylon and cellophane.

  The printing ink composition of the present invention is excellent in dryness even when printed at a high speed, and has a high gloss, a clear hue and heat resistance as a printed matter, and is also good for complicatedly overlapping designs. Has overprintability. Furthermore, the printing ink composition of the present invention is effective for printing on water-repellent paper having at least an organic solvent content and low wettability as a water-based ink.

  EXAMPLES Hereinafter, although an Example demonstrates this invention more concretely, this invention is not limited to these Examples.

  Unless otherwise specified, “part” and “%” in this example represent “part by mass” and “% by mass”.

<Styrene / α-olefin / maleic acid copolymer resin of Examples 1 to 11 and Comparative Examples 2 to 5>
In an autoclave, maleic anhydride, styrene, α-olefin, methacrylic acid, butyl acrylate, and toluene and azobisisobutyronitrile having the proportions shown in Table 1 were charged, and stirred and reacted at 60 ° C. in a nitrogen stream. Was distilled off to obtain each styrene / α-olefin / maleic acid copolymer, and then a hydroxyl group-containing compound was added so as to have the ratio shown in Table 1, followed by addition reaction at 180 ° C. 11. The styrene / α-olefin / maleic acid copolymer resin of Comparative Examples 2 to 5 was obtained.

<Α-Olefin / Maleic Acid Copolymer Resin of Comparative Example 1>
In an autoclave, maleic anhydride and α-olefin having the proportions shown in Table 1 were charged with toluene and azobisisobutyronitrile. The mixture was stirred and reacted at 60 ° C. in a nitrogen stream. An olefin / maleic acid copolymer was obtained, and then a hydroxyl group-containing compound was added so as to have the ratio shown in Table 1, followed by addition reaction at 180 ° C. to obtain the α-olefin / maleic acid copolymer resin of Comparative Example 1. Obtained.

<Binder resin for ink>
A four-necked flask equipped with a stirrer, a cooling tube, and a nitrogen gas introduction tube was charged with 350 parts of ethyl acetate and heated to 75 ° C., while introducing nitrogen gas, 100 parts of styrene, 100 parts of methyl methacrylate, methacrylic acid A mixture of 50 parts and 2.5 parts of ditertiary butyl peroxide as an initiator was added dropwise over 2 hours, and further copolymerized for 2 hours while maintaining the same temperature. A binder resin for ink having a molecular weight of 18000 and an acid value of 130 was obtained.

<Method for producing aqueous resin varnish>
Amine aqueous solution 70 in which 30 parts of each of the copolymer resins of Examples 1 to 11 and Comparative Examples 1 to 5 obtained by the above method were dissolved in ammonia corresponding to 105% of the copolymer neutralization amount. The aqueous resin varnishes of Examples 1 to 11 and Comparative Examples 1 to 5 were prepared by heating and dissolving in the parts.

  Ink binder resin varnish was prepared by dissolving 40 parts of the above ink binder resin in 60 parts of an aqueous amine solution in which ammonia corresponding to 105% of the copolymer was neutralized.

<Blue aqueous pigment dispersions of Examples 1 to 11 and Comparative Examples 1 to 5>
As a blue pigment, 30 parts by mass of a relatively hydrophobic phthalocyanine blue pigment (TRG, manufactured by DIC) and 16 parts of the aqueous resin varnishes of Examples 1 to 11 and Comparative Examples 1 to 5 were stirred and mixed to bead mill. Then, 54 parts of water was further added and stirred to obtain blue aqueous pigment dispersions of Examples 1 to 11 and Comparative Examples 1 to 5.

<Blue aqueous pigment dispersion of Example 12>
As a blue pigment, 30 parts by mass of a relatively hydrophobic phthalocyanine blue pigment (TRG, manufactured by DIC) and 3.7 parts by mass of the aqueous resin varnish of Example 1 were stirred and mixed, and then kneaded with a bead mill. Further, 66.3 parts of water was added and stirred to obtain a blue aqueous pigment dispersion of Example 12.

<Blue aqueous pigment dispersion of Example 13>
As a blue pigment, 30 parts by mass of a relatively hydrophobic phthalocyanine blue pigment (TRG, manufactured by DIC) and 10 parts by mass of the aqueous resin varnish of Example 1 were mixed by stirring and kneaded with a bead mill. 60 parts of water was added and stirred to obtain a blue aqueous pigment dispersion of Example 13.

<Blue aqueous pigment dispersion of Example 14>
As a blue pigment, 30 parts by mass of a relatively hydrophobic phthalocyanine blue pigment (TRG, manufactured by DIC) and 29 parts by mass of the aqueous resin varnish of Example 1 were mixed by stirring and kneaded with a bead mill. 41 parts of water was added and stirred to obtain a blue aqueous pigment dispersion of Example 14.

<Blue aqueous pigment dispersion of Example 15>
As a blue pigment, 30 parts by mass of a relatively hydrophobic phthalocyanine blue pigment (TRG, manufactured by DIC), 5 parts by mass of the aqueous resin varnish of Example 1 were stirred and mixed, and then kneaded with a bead mill. 65 parts of water was added and stirred to obtain a blue aqueous pigment dispersion of Example 15.

<Blue aqueous pigment dispersion of Comparative Example 6>
As the blue pigment, 30 parts by mass of a relatively hydrophobic phthalocyanine blue pigment (TRG, manufactured by DIC), 2.4 parts by mass of the aqueous resin varnish of Example 1, and 67.6 of water were added and stirred. Thus, a blue aqueous pigment dispersion of Comparative Example 6 was obtained.

<Production of white aqueous pigment dispersion>
30 parts by mass of titanium oxide and 13.3 parts by mass of the aqueous resin varnish of Comparative Example 1 were stirred and mixed, and then kneaded with a bead mill. Further, 60 parts of water was added and stirred to obtain a white aqueous pigment dispersion.

<Blue aqueous printing ink composition>
The aqueous pigment dispersion of 40 parts of comparative examples except those having poor storage stability in Examples and Examples, 30 parts of binder resin varnish for water-based ink were added, and after bead milling, the total amount of binder resin varnish for water-based ink and water A blue water-based printing ink was obtained in an amount of 30 parts and diluted such that the viscosity of the system was 1.5 poise at 20 ° C.

<Evaluation of Examples and Comparative Examples>
About the water-based pigment dispersion and water-based printing ink obtained by the above Example and the comparative example, performance was evaluated by the following evaluation items, and the result was shown to Table 1 and 2. FIG.

<Evaluation of aqueous pigment dispersion>
Storage stability The storage stability was evaluated from the ratio of the viscosity immediately after preparation of the aqueous pigment dispersion (initial viscosity) and the viscosity after aging for 7 days at an ambient temperature of 40 ° C. (viscosity with time).
Viscosity with time / initial viscosity (B-type viscometer, 30 rpm)

Evaluation criteria A: Viscosity ratio is 1.5 or less B: Viscosity ratio exceeds 1.5 and 2.0 or less C: Viscosity ratio exceeds 2.0 and 3.0 or less D: Viscosity The ratio exceeds 3.0

Coloring power To dilute 10 parts of the aqueous pigment dispersions of the examples and comparative examples until 10 parts of the aqueous pigment dispersion of comparative example 1 are identical to the color density when diluted with 100 parts of the aqueous white pigment dispersion. The coloring power of the blue aqueous pigment dispersion was evaluated based on the amount of the aqueous white pigment dispersion required.

Gloss The sample ink was developed with a 165-line hand proofer on a Rengo CRC liner (manufactured by Rengo Co., Ltd.), and the gloss value was measured with a 75 ° gloss meter to evaluate the gloss.

Evaluation criteria A: The measured value is 60 or more B: The measured value is 50 or more and less than 60 C: The measured value is less than 50

<Evaluation of water-based printing ink composition>
Bronze float Sample ink was developed on a Rengo CRC liner (manufactured by Rengo Co., Ltd.) with a 0.15 mm Meyer bar, and the presence or absence of bronze float was visually determined.

Evaluation criteria A: No bronzing is observed.
B: The bronze float is observed in less than 50% of the color development area.
C: The bronze float is seen in 50% or more of the color development area.

Water-repellent paper suitability Water-repellent paper is applied to water-repellent paper (Oji Paper Co., Ltd., Super K) using a 165-line hand proofer to visually determine the degree of ink transfer and color unevenness. Suitability was evaluated.

Evaluation Criteria A: No missing on the printed surface and no color unevenness B: No missing on the printed surface, but slightly colored unevenness C: There are missing on the printed surface, and the color unevenness is severe thing

Water resistant K liner (Oji Paper Co., Ltd., K) is used to color the sample ink with a 165-line hand proofer, and after drying, 0.2 g of water is applied to the backing paper using a Gakken type fastness tester. Friction 50 times with a load of 200 g while using the soaked glazing. The degree of coloring of the backing paper was determined visually to evaluate water resistance.

Evaluation Criteria A: The paper is not colored at all B: The paper is slightly colored C: The paper is darkly colored

Drying property In an environment at room temperature of 20 ° C. and a relative humidity of 60%, the sample ink was developed with a 0.15 mm mailer on a K liner (manufactured by Oji Paper Co., Ltd.), and the drying property was evaluated by finger touch.
A: Dried within 3 seconds after color development C: Dried over 3 seconds after color development

Heat resistance Kink liner (manufactured by Oji Paper Co., Ltd., K) was used to color the sample ink with a 165-line hand proofer, dried, and then placed on top of it with an aluminum foil, heated at 180 ° C, load 2 kg. After squeezing for 5 seconds at / cm ² , it was judged whether or not the ink adhered to the aluminum foil.

Claims (3)

In an aqueous pigment dispersion in which a pigment is dispersed in water using a pigment dispersing resin, all of the styrene monomer, styrene / α-olefin / maleic acid copolymer resin are used as the pigment dispersing resin. It is obtained by copolymerizing an α-olefin monomer in the range of 3 to 15% by mass and a radically polymerizable monomer having a maleic acid monomer as a main component in a constituent component. Acid value containing at least one group represented by the following general formula (1) and group represented by the following general formula (2) in the molecule based on a reaction with an anhydride ring or a carboxyl group of a monomer It contains 90 to 240 mg KOH / g and a styrene / α-olefin / maleic acid copolymer resin having a weight average molecular weight of 2000 to 40000 in a ratio of 3 to 20 parts by mass with respect to 100 parts by mass of the pigment. water On the pigment dispersion.
_{-COO- (C 2 H 4 O)} p (C 3 H 6 O) qR1 general formula (1)
(Where R1 is H or an alkyl group having 1 to 8 carbon atoms, p and q are integers of 0 or more, p + q ≧ 1, and the formula weight of the general formula (1) is 494 or less. The number of combinations that satisfy the conditions
-COO-R2 Formula (2)
(Here, R2 is a hydrocarbon group having 1 to 8 carbon atoms.) The group represented by the general formula (1) is p = 1 to 3, q = 0, R1 is an alkyl group having 1 to 4 carbon atoms, and the group represented by the general formula (2) is R2 The aqueous pigment dispersion according to claim 1, comprising a styrene / α-olefin / maleic acid copolymer resin which is an alkyl group having 1 to 4 carbon atoms. An aqueous printing ink composition comprising the aqueous pigment dispersion according to claim 1.