WO2014156460A1 - Ink composition for inkjet recording, ink set for inkjet recording, and inkjet recording method - Google Patents

Abstract

The main purpose of the present invention is to provide an ink composition for inkjet recording having excellent dispersion stability and making it possible to produce a printed product having excellent water resistance, chemical resistance, and image sharpness. The present invention achieves this purpose by providing an ink composition for inkjet recording having a resin, a surfactant, a pigment, and a solvent, the ink composition for inkjet recording being characterized in that the resin has an acid value within the range of 0-20 mg KOH/g and is in a state of emulsion in the ink composition for inkjet recording, and the surfactant contains a compound represented by general formula (1) and a polysiloxane compound.

Description

Ink composition for ink jet recording, ink set for ink jet recording, ink jet recording method

The present invention relates to an ink composition for ink jet recording, which is excellent in dispersion stability, can produce a printed matter excellent in water resistance and solvent resistance and image sharpness.

When printing using the inkjet method, the ink ejected from the printer head lands on the recording medium, and then penetrates and fixes to form dots, and an image is formed by collecting a large number of these dots. This dot formation process is important for forming a clear image.
For example, non-coated paper such as high-quality paper and plain paper widely used for recording media is made of a hydrophilic substance with many hydroxyl groups of cellulose and has a property that it is easy to become familiar with water. It absorbs water and swells. It has the property to do. For this reason, water-based ink is generally used as the ink.
In recent years, small lots and many types of printed materials have been developed, and as an alternative to conventional offset printing, inkjet printing, which is on-demand printing that is easily compatible with high-speed printing, has attracted attention. Inkjet ink for coated paper Printing using is expected.
The coated paper includes, for example, coated paper, art paper, cast paper, etc., and is used for printed materials that require high reproducibility such as calendars, posters, magazine color pages, etc. A solution (coating solution) in which a white pigment mainly composed of kaolin, calcium carbonate or the like and a binder are dispersed in water is applied, and a coating layer is formed on the surface. Synthetic latex or the like is mainly used as the binder, and the hydrophobic coating layer is formed by filling the gaps between the pigment particles.
For this reason, when printing on coated paper using general water-based ink, the ink is less likely to penetrate into the recording medium compared to non-coated paper, and the ink is repelled uniformly on the coated paper surface. There was a problem that it could not be applied and the water resistance and solvent resistance of the printed matter was insufficient.
Also, ink that has landed on the coated paper by the inkjet method has low penetrability as described above, and since it is repelled on the coated paper surface, the dots do not spread sufficiently and the dot diameter tends to be small. If it is small, the coloring material cannot be applied uniformly on the surface of the recording medium, which causes printing unevenness, excessive gaps between dots, white spots, and poor image clarity. was there.

A method for forming a layer for fixing a color material of ink on the surface of a recording medium (for example, Patent Documents 1 to 5) and a method for optimizing ink components such as a dispersant (for example, Patent Documents 6 to 16) are disclosed. Has been.

However, in these methods, when used for non-coated paper having high ink absorbability, it can be made excellent in image sharpness and the like. In contrast, there is a problem that it is impossible to produce a printed matter that exhibits sufficient water resistance.
In addition, when used for non-coated paper or the like, there is a problem that a printed matter having sufficient water resistance cannot be produced.
For example, in Patent Documents 6 to 7, when used on coated paper, there is a problem that the ink spreads and the drying property becomes insufficient. Further, Patent Documents 8 to 12 have a problem that water resistance is insufficient when used on coated paper.

JP-A-57-069054 JP-A-1-63185 Japanese Patent Laid-Open No. 6-143797 JP 2000-168228 A JP 2009-178912 A Special table 2009-513802 Special table 2009-515007 JP-T-2004-510028 JP 2007-277356 A JP 2006-241279 A JP-A-9-207424 JP 2005-264115 A JP 2007-161923 A JP 2009-235387 A JP 2006-218661 A JP 2003-268268 A

The present invention has been made in view of the above-described problems, and provides an ink composition for ink jet recording capable of producing a printed matter having excellent dispersion stability, water resistance and solvent resistance, and excellent image sharpness. This is the main purpose.

As a result of repeated research to solve the above problems, the present inventors have conventionally aimed at printing on non-coated paper and the like, and a resin having a high polarity as a resin component contained in ink for improving dispersion stability However, when printing on coated paper, such a resin with a high polarity makes the printed material low in water resistance, etc., and has a low acid value. It has been found that a printed matter excellent in water resistance and solvent resistance can be produced by using. In addition, although a resin having a low acid value has a low dispersion stability in a water-based ink, good dispersion stability can be obtained even in a water-based ink by using a compound represented by the following general formula (1). In addition, by including both the compound represented by the above formula (1) and the polysiloxane compound, it should have an excellent balance between permeability to coated paper and wet spreadability. I found out that I can.
In addition, when printed on non-coated paper, it is possible to produce printed matter with excellent permeability and drying property, and excellent water resistance and solvent resistance due to high permeability. However, the present inventors have found that it is possible to produce a printed matter excellent in water resistance, solvent resistance and image sharpness, and have completed the present invention.

That is, the present invention is an ink composition for ink jet recording (hereinafter sometimes referred to simply as ink) having a resin, a surfactant, a pigment, and a solvent, and the resin has an acid value. 0 mg KOH / g to 20 mg KOH / g (hereinafter, such a resin may be a low acid value resin), is in an emulsion state in the ink composition for ink jet recording, and has the surface activity. The agent provides an ink composition for ink jet recording, comprising a compound represented by the following general formula (1) and a polysiloxane compound.

(In Formula (1), R ¹ and R ² are each hydrogen or a linear or branched alkyl group having 1 to 20 carbon atoms. M and n are each an integer of 0 to 20. M is monovalent. )

According to the present invention, by including the low acid value resin and the surfactant, it is possible to produce a printed matter having excellent dispersion stability, water resistance, solvent resistance, and image sharpness. be able to.

The present invention includes two or more of the ink jet recording ink compositions described above, wherein the ink jet recording ink composition has a surface tension in the range of 20 mN / m to 30 mN / m, and all of the ink jet recording ink compositions described above. An ink set for ink jet recording (hereinafter, sometimes simply referred to as an ink set) is provided, in which the difference in surface tension between them is 1 mN / m or less.

According to the present invention, the difference in surface tension between the ink compositions is within the above-described range, so that blur between different colors (between inks) is small and image sharpness is excellent. it can.

The present invention provides an ink set for ink jet recording comprising the above ink composition for ink jet recording and a receiving solution containing a polyvalent metal salt.

According to the present invention, by using the ink together with a receiving solution, it is possible to produce a printed matter with less ink bleeding and excellent image sharpness when the ink is used.

The present invention provides an ink jet recording method characterized by printing by the ink jet method using the ink composition for ink jet recording described above.

According to the present invention, a printed matter excellent in water resistance, solvent resistance, and image sharpness can be created by using the above ink.

The present invention provides an ink jet recording method characterized by printing by the ink jet method using the ink set for ink jet recording described above.

According to the present invention, a printed matter with excellent image sharpness can be created by using the ink set.

The present invention has an effect that it can provide an ink composition for ink-jet recording which is excellent in dispersion stability, can produce a printed matter excellent in water resistance and solvent resistance and image sharpness.

The present invention relates to an ink composition for ink jet recording, an ink set for ink jet recording, and an ink jet recording method.
Hereinafter, the ink composition for ink jet recording, the ink set for ink jet recording, and the ink jet recording method of the present invention will be described.

A. Ink composition for ink jet recording The ink composition for ink jet recording of the present invention is an ink composition for ink jet recording having a resin, a surfactant, a pigment, and a solvent. The resin has an acid value of 0 mgKOH. / G to 20 mgKOH / g, and is in an emulsion state in the ink composition for ink jet recording, and the surfactant contains a compound represented by the following general formula (1) and a polysiloxane compound. It is a feature.

(In Formula (1), R ¹ and R ² are each hydrogen or a linear or branched alkyl group having 1 to 20 carbon atoms. M and n are each an integer of 0 to 20. M is monovalent. )

According to the present invention, by including the low acid value resin and the surfactant, it is possible to produce a printed matter having excellent dispersion stability, water resistance, solvent resistance, and image sharpness. be able to.
Here, the reason why such an effect can be obtained by including the resin and the surfactant is presumed as follows.

That is, by using a resin having a low acid value and a low polarity as described above, water resistance can be improved. Moreover, since the acid value is low, the amount of the neutralizing agent required at the time of resin synthesis can be reduced. Also from such a thing, it can be made more excellent in water resistance. Furthermore, since the acid value is low, it can have excellent solvent resistance not only for water but also for highly polar solvents such as esters and alcohols.
Therefore, by using such a resin, it can be made excellent in water resistance and solvent resistance.
In addition, due to such excellent water resistance and solvent resistance, when the printed surface is covered with a film, the printed surface is less likely to move to the film due to residual solvent or plasticizer in the film or stick to the film. Can be.

In addition, since the compound represented by the above formula (1) is ionic, it can be dissolved in water, and the linear or branched alkyl group contained in the compound represented by the above formula (1) is a resin and Because of its good affinity, the compound represented by the above formula (1) exists at the interface between the resin and the aqueous solvent, and it is an anionic group, and the molecule has a sulfonyl group exhibiting large steric hindrance. This makes it possible to effectively impart electrostatic repulsion to the resin. For this reason, the resin can be excellent in dispersion stability in an aqueous solvent.
Furthermore, the compound represented by the above formula (1) has a comb structure in which two linear or branched alkyl groups are present in one molecule and one anionic group is present in one molecule. The effect of penetrating ink into the coated paper on which the hydrophobic coating layer is formed is high. For this reason, it is possible to make the ink excellent in permeability even for coated paper that generally has low ink absorbability, and it is possible to prevent ink from remaining on the coated paper surface and bleeding. .
On the other hand, the polysiloxane compound has a high surface tension reducing effect, and can make the ink excellent in wetting and spreading even on the coated paper surface on which the coating layer is formed.
Therefore, by including a polysiloxane compound together with the compound represented by the above formula (1) as a surfactant, it is possible to achieve an excellent balance between permeability to coated paper and wet spreadability, and image clarity. It can be made excellent in properties.
In addition, when printed on non-coated paper, since the permeability is high, it is possible to provide an ink composition excellent in fixing property and drying property. Furthermore, it is possible to create a printed matter excellent in resistance and image sharpness even on a substrate other than paper.
Therefore, by including the resin and the surfactant, it is possible to produce a printed material having excellent dispersion stability, water resistance and solvent resistance, and image sharpness. is there.

The ink of the present invention has a resin, a surfactant, a pigment, and a solvent.
Hereinafter, each component of the ink of the present invention will be described in detail.

1. Resin The resin used in the present invention has an acid value in the range of 0 mgKOH / g to 20 mgKOH / g, and is in an emulsion state in ink.
Here, the emulsion state means that the resin is dispersed in the ink as resin fine particles.
In addition, the resin in the emulsion state generally has a property of thickening and aggregating when the organic solvent or water, which is a continuous phase, is reduced by evaporation, penetration, etc., and controls the penetration of the pigment into the recording medium. Fixing on a medium can be promoted.

Such a resin is not particularly limited as long as it can exhibit desired water resistance and solvent resistance. For example, acrylic resin, polystyrene resin, polyester resin, vinyl chloride resin, vinyl acetate A resin, a vinyl chloride vinyl acetate copolymer resin, a polyethylene resin, a urethane resin, a silicone (silicon) resin, an acrylamide resin, an epoxy resin, or a copolymer or a mixed form thereof can be used.
In the present invention, it is preferable that an acrylic resin is included. This is because the resin can be excellent in water resistance and solvent resistance.

The monomer constituting the acrylic resin is not particularly limited as long as it contains a (meth) acrylic acid ester monomer having no acid group or hydroxyl group as a main component.
In addition, an acid group is what the aqueous solution or water suspension of the monomer which has the said group shows acidity. Specific examples include a carboxyl group, a phosphoric acid group and a sulfonic acid group, and acid anhydrides and acid halides thereof.

As the (meth) acrylic acid ester monomer, known compounds can be used, and monofunctional (meth) acrylic acid esters can be preferably used. Examples thereof include (meth) acrylic acid alkyl esters, (meth) acrylic acid aralkyl esters, (meth) acrylic acid alkoxyalkyl esters, and the like. Specifically, for example, methyl (meth) acrylate, ethyl (meth) acrylate, (meth) acrylic acid-n-propyl, (meth) acrylic acid-iso-propyl, (meth) acrylic acid-n-butyl , (Meth) acrylic acid-sec-butyl, (meth) acrylic acid-iso-butyl, (meth) acrylic acid-tert-butyl, (meth) acrylic acid pentyl, (meth) acrylic acid neopentyl, (meth) acrylic acid Hexyl, (meth) acrylic acid-2-ethylhexyl, (meth) acrylic acid octyl, (meth) acrylic acid-iso-octyl, (meth) acrylic acid nonyl, (meth) acrylic acid-iso-nonyl, (meth) acrylic Dodecyl acid, Tridecyl (meth) acrylate, Stearyl (meth) acrylate, Cyclopentyl (meth) acrylate, Cyclohexyl (meth) acrylate Sil, (meth) acrylic acid-2-methylcyclohexyl, (meth) acrylic acid dicyclopentanyl, (meth) acrylic acid dicyclopentenyl, (meth) acrylic acid dicyclopentanyloxyethyl, (meth) acrylic acid di Cyclopentenyloxyethyl, dicyclohexyl (meth) acrylate, isobornyl (meth) acrylate, adamantyl (meth) acrylate, allyl (meth) acrylate, propargyl (meth) acrylate, phenyl (meth) acrylate, (meth) Naphtyl acrylate, Anthracenyl (meth) acrylate, Anthraninonyl (meth) acrylate, Piperonyl (meth) acrylate, Salicyl (meth) acrylate, Furyl (meth) acrylate, Furfuryl (meth) acrylate, (Metal ) Tetrahydrofuryl acrylate, (Me ) Tetrahydrofurfuryl acrylate, pyranyl (meth) acrylate, benzyl (meth) acrylate, phenethyl (meth) acrylate, cresyl (meth) acrylate, glycidyl (meth) acrylate, (meth) acrylic acid-3, 4-epoxycyclohexylmethyl, (meth) acrylic acid-3,4-epoxycyclohexylethyl, (meth) acrylic acid-1,1,1-trifluoroethyl, (meth) acrylic acid perfluoroethyl, (meth) acrylic Perfluoro-n-propyl acid, perfluoro-iso-propyl (meth) acrylate, heptadecafluorodecyl (meth) acrylate, triphenylmethyl (meth) acrylate, cumyl (meth) acrylate, (meth) acrylic Acid-3- (N, N-dimethylamino) propyl, (meth) acrylic acid Toxiethyl, ethoxyethyl (meth) acrylate, butoxyethyl (meth) acrylate, 2-cyanoethyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, (meth) acrylic acid And (meth) acrylic acid esters such as trimethoxysilylpropyl, trimethoxysilylpropyl (meth) acrylate, 3-methacryloxypropylmethyldiethoxysilane, and 3-methacryloxypropylmethyldimethoxysilane. “(Meth) acryl” means both “acryl” and “methacryl”. These monomers can be obtained from Mitsubishi Rayon Co., Ltd., Nippon Oil & Fat Co., Ltd., Mitsubishi Chemical Co., Ltd., Hitachi Chemical Co., Ltd., etc.

The content of the (meth) acrylic acid ester monomer is not particularly limited as long as it is contained as a main component in the acrylic resin. For example, in the acrylic resin, the content is 50% by mass or more. In particular, it is preferably in the range of 60% by mass to 100% by mass, and more preferably in the range of 70% by mass to 99.99% by mass. It is because it can be made excellent in water resistance and solvent resistance because the content is within the above range.
In addition, content of a monomer is a ratio which occupies for all the monomers used in order to comprise resin.

The monomer constituting the acrylic resin may include an acid group-containing monomer having an acid group or a hydroxyl group-containing monomer having a hydroxyl group.

Examples of the acid group-containing monomer having an acid group include a carboxyl group-containing monomer having an ethylenically unsaturated double bond and a carboxyl group such as acrylic acid, methacrylic acid, itaconic acid, fumaric acid, and maleic acid. it can.
The content of the acid group-containing monomer is not particularly limited as long as it can have the acid value, but is preferably 5% by mass or less in the acrylic resin. In particular, the content is preferably 3% by mass or less, and more preferably 0.01% by mass to 2% by mass. It is because the resin having the acid value can be easily formed by being within the range of the content.

The hydroxyl group-containing monomer is not particularly limited as long as it has an unsaturated double bond and a hydroxyl group. For example, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate and methyl α -(Hydroxymethyl) (meth) acrylate, ethyl α- (hydroxymethyl) (meth) acrylate, n-butyl α- (hydroxymethyl) (meth) acrylate, 1,4-cyclohexanedimethanol mono (meth) acrylate, 4 -Hydroxybutyl (meth) acrylate and the like.
The content of the hydroxyl group-containing monomer in the present invention is not particularly limited as long as it can produce a printed matter having desired water resistance and solvent resistance. For example, 5 mass% in the acrylic resin. In particular, it is preferably 3% by mass or less, and more preferably 2% by mass or less. It is because it can make the printed material excellent in water resistance and solvent resistance by being in the range of the said content.

As a monomer which comprises the said acrylic resin, you may have another monomer as needed other than the said (meth) acrylic acid ester monomer.
Such other monomers are not particularly limited as long as they can have desired water resistance and solvent resistance, and the number of ethylenically unsaturated double bonds is one. It may be a certain monofunctional monomer or a polyfunctional monomer having 2 or more.
For example, vinyl monomers such as vinyl acetate, vinyl chloride, vinylidene chloride, vinyl fluoride, vinylidene fluoride, N-vinyl pyrrolidone, vinyl pyridine, N-vinyl carbazole, vinyl imidazole, vinyl ether, vinyl ketone, vinyl pyrrolidone; styrene, styrene α-, o-, m-, p-alkyl, nitro, cyano, amide, ester derivatives, aromatic vinyl monomers such as vinyltoluene and chlorostyrene; olefin monomers such as ethylene, propylene, isopropylene; butadiene, chloroprene, etc. Diene monomer; Vinyl cyanide monomer such as acrylonitrile and methacrylonitrile; Acrylamide monomer such as acrylamide and N, N-dimethylacrylamide, (meth) acrylic acid anilide, N-benzyl Reimido, N- phenylmaleimide, N- cyclohexyl maleimide, N- lauric maleimide, N- (4-hydroxyphenyl) monomaleimide such as maleimides, may be used phthalimide such as N- (meth) acryloyl phthalimide.
In addition, diacrylate compounds such as polyethylene glycol diacrylate, triethylene glycol diacrylate, and 1,3-butylene glycol diacrylate; triacrylate compounds such as trimethylolpropane triacrylate, trimethylolethane triacrylate, and tetramethylolmethane triacrylate Dimethacrylate compounds such as ethylene glycol dimethacrylate, diethylene glycol dimethacrylate and triethylene glycol dimethacrylate; trimethacrylate compounds such as trimethylolpropane trimethacrylate and trimethylolethane trimethacrylate; divinylbenzene and the like can be used.

The acrylic resin can be formed using these monomers, but the copolymerization form of the monomers is not particularly limited, and for example, a block copolymer, a random copolymer, a graft copolymer, or the like is used. be able to.

The acid value of the resin is not particularly limited as long as it is in the range of 0 mgKOH / g to 20 mgKOH / g in terms of solid content, but is preferably in the range of 0 mgKOH / g to 15 mgKOH / g. In particular, it is preferably in the range of 0 mgKOH / g to 13 mgKOH / g, and particularly preferably in the range of 0 mgKOH / g to 10 mgKOH / g. This is because, when the acid value is within the above range, the printed matter can be excellent in water resistance and solvent resistance. In addition, it is possible to reduce the interaction between the resin, the dispersant, and the pigment, and to suppress changes in physical properties such as surface tension and viscosity, thereby improving the storage stability of the ink.
In addition, an acid value is the mg number of potassium hydroxide required in order to neutralize the acidic component contained in 1g of samples (solid content of resin).
Moreover, such an acid value can be adjusted with the kind, content, etc. of the monomer which comprises resin.

The hydroxyl value of the resin is not particularly limited as long as a printed matter having desired water resistance and solvent resistance can be produced. For example, the hydroxyl value is within the range of 0 mgKOH / g to 20 mgKOH / g in terms of solid content. In particular, it is preferably in the range of 0 mgKOH / g to 15 mgKOH / g, and particularly preferably in the range of 0 mgKOH / g to 10 mgKOH / g. This is because when the hydroxyl value is within the above range, a printed matter having good water resistance, solvent resistance, and friction resistance can be produced.
The hydroxyl value is the number of mg of potassium hydroxide required to acetylate the hydroxyl content contained in 1 g of the sample (solid content of the resin).
As a method for measuring the hydroxyl value, a method can be used in which acetic anhydride is used to acetylate the hydroxyl group of the resin in the sample, and the remaining acetic acid is neutralized with potassium hydroxide. The hydroxyl value in the present invention does not include those due to the OH group contained in the carboxyl group.
Such a hydroxyl value can be adjusted by the kind and content of the monomer constituting the resin.

The molecular weight of the resin is not particularly limited as long as a printed matter having desired water resistance and solvent resistance can be produced. For example, it is preferably 10,000 or more, and more preferably 10,000 to 1,000,000. It is preferably within the range, and particularly preferably 10,000 to 500,000. This is because when the molecular weight is within the above range, an emulsion state having excellent dispersion stability can be obtained.
The above molecular weight indicates the weight average molecular weight Mw, and is a value measured by GPC (gel permeation chromatography) (manufactured by Tosoh Corporation, HLC-8120GPC). N-methylpyrrolidone to which lithium bromide is added / liter, and polystyrene standards for calibration curves are Mw377400, 210500, 96000, 50400, 206500, 10850, 5460, 2930, 1300, 580 (Easi PS- manufactured by Polymer Laboratories) 2 series) and Mw 1090000 (manufactured by Tosoh Corp.), and the measurement column is TSK-GEL ALPHA-M × 2 (manufactured by Tosoh Corp.).

The glass transition temperature of the resin (hereinafter sometimes referred to as Tg) is not particularly limited as long as a printed matter having desired water resistance and solvent resistance can be formed. It is preferably in the range of ˜90 ° C., more preferably in the range of 15 ° C. to 80 ° C., and particularly preferably in the range of 20 ° C. to 70 ° C. This is because when the Tg is within the above range, the printed surface is less sticky after drying, and the printed matter can be excellent in resistance. Moreover, it is because generation | occurrence | production of the blocking which is a malfunction which the printing surface of a printed matter adhere | attaches another member, for example, when a printed matter is piled up can be suppressed because there are few stickiness. Moreover, it is because it can avoid applying high temperature in order to form printed matter, a lot of energy can be made unnecessary, and the printing base material can be made not to be damaged by heat.
In addition, such Tg can be adjusted with the kind, content, etc. of the monomer which comprises resin.

The conductivity of the resin is not particularly limited as long as a printed matter having desired water resistance and solvent resistance can be formed, but is preferably 300 μS / cm or less, and more preferably 200 μS / cm or less. In particular, it is preferably 150 μS / cm or less. This is because when the conductivity is within the above-mentioned range, the ionic group and its counter ion or ionic impurity in the resin are few, the resin acid value is low, and the polarity can be low. Moreover, it is because it has few influence on the dispersion stability of a pigment because there are few ionic groups etc. In particular, when a self-dispersing pigment having a functional group such as a hydrophilic group introduced on the pigment surface is used as a pigment, the reactivity of the resin and the self-dispersing pigment is lowered due to the low conductivity of the resin. This is because the storage stability of the ink can be improved.
Also, for this reason, the lower limit of the conductivity of the resin is preferably as low as possible, but is usually about 20 μS / cm. This is because the resin has excellent dispersion stability and it is easy to produce a resin having a stable quality.
In addition, the said conductivity shows the conductivity of 1 mass% solid content aqueous solution of the said resin.
As a method for measuring the conductivity, first, the resin is diluted with ion-exchanged water to adjust the solid content to 1% by mass, and then the conductivity of the 1% by mass resin solid solution is measured using a conductivity meter. The method can be adopted. Further, as a conductivity meter, a model: EC Testr 11+ manufactured by Eutech Instruments can be used.
The conductivity of such a 1% by weight aqueous solution of resin can be adjusted, for example, by the type of resin, monomer type, reaction mechanism, type of emulsifier, presence / absence of addition of an emulsifier, type of neutralizing agent, and the like. .

The content of the resin is not particularly limited as long as a printed matter having desired water resistance and solvent resistance can be formed. For example, the resin content is in the range of 0.05% by mass to 20% by mass. In particular, the content is preferably in the range of 0.1% by mass to 20% by mass, and more preferably in the range of 1% by mass to 20% by mass. It is because it can be made excellent in water resistance and solvent resistance because the content is within the above range.

The average particle diameter of the resin in the ink is not particularly limited as long as it can be excellent in dispersion stability, but is preferably 500 nm or less, more preferably 200 nm or less, and further 150 nm or less is more preferable. This is because, when the average particle diameter is within the above-described range, the emulsion stability, ink ejection property, and gloss of printed matter can be improved. In addition, since it is so preferable that the minimum of an average particle diameter is small, it is not specifically limited, Usually, it is about 30 nm.
The average particle diameter can be determined by a dynamic light scattering method. The dynamic light scattering method is a method of measuring the particle size using the fact that the light intensity distribution of the diffracted scattered light varies depending on the particle size when laser light is applied to the particle. For example, Nikkiso Co., Ltd. The measurement can be performed using a Microtrac particle size distribution analyzer UPA manufactured by Otsuka Electronics Co., Ltd., or a dense particle size analyzer FPAR-1000 manufactured by Otsuka Electronics. In addition, the measurement is performed under the conditions of a measurement temperature of 25 ° C., an integration time of 3 minutes, and a wavelength of the laser used for the measurement of 660 nm, and the obtained data is analyzed by the CONTIN method to obtain a scattering intensity distribution. A high particle size can be the average particle size.

The method for synthesizing the resin is not particularly limited as long as it is a method capable of synthesizing a resin having a desired monomer composition ratio and molecular weight, and a general synthesis method can be used. For example, when the resin is an acrylic resin, it is possible to use a method in which water, a monomer, an emulsifier, and a polymerization initiator are mixed and subjected to an emulsion polymerization reaction and neutralized after the reaction.
As such an emulsifier, those generally used for emulsion polymerization can be used, and specifically, those described in JP 2012-51357 A can be used.

2. Surfactant The surfactant used in the present invention contains a compound represented by the above formula (1) and a polysiloxane compound.

(1) Compound represented by Formula (1) The compound represented by Formula (1) used in the present invention is a monoalkylsulfosuccinate, dialkylsulfosuccinate, monopolyoxy represented by the following general formula (1). It is a salt such as ethylene alkyl sulphosuccinate and dipolyoxyethylene alkyl sulphosuccinate, and improves the dispersion stability of the resin in ink.

(In Formula (1), R ¹ and R ² are each hydrogen or a linear or branched alkyl group having 1 to 20 carbon atoms. M and n are each an integer of 0 to 20. M is monovalent. )

R ¹ and R ² are each hydrogen or a linear or branched alkyl group having 1 to 20 carbon atoms, and are not particularly limited as long as the dispersion stability of the resin can be improved. A linear or branched alkyl group having 4 to 20 carbon atoms is preferable, and a linear or branched alkyl group having 4 to 12 carbon atoms is particularly preferable. This is because the affinity with the resin is high and the effect of improving dispersibility is high.

m and n are not particularly limited as long as they can improve the dispersion stability of the resin as long as they are integers of 0 to 20, and the number of ethylene oxide repeats suitable for the type of resin or solvent Can be appropriately selected.

M is a monovalent cation and is not particularly limited as long as it can improve the dispersion stability of the resin. For example, lithium (Li ⁺ ), sodium (Na ⁺ ), potassium (K ⁺ ), ammonia (NH ₄ ⁺ ), triethanolamine ((HOCH ₂ CH ₂ C) ₃ NH ⁺ ), and the like, among others, changes in viscosity and surface tension during long-term storage of ink, etc. Sodium (Na ⁺ ) and potassium (K ⁺ ) are preferable from the viewpoint of storage stability, such as suppression of odor.

Specific examples of the compound represented by the above formula (1) include AEROSOL TR-70 (ditridecylsulfosuccinate sodium), TR-70HG (ditridecylsulfosuccinate sodium) manufactured by Nippon Cytec Industries, Ltd., OT-75 (sodium dioctylsulfosuccinate), OT-N (sodium dioctylsulfosuccinate), MA-80 (sodium dihexylsulfosuccinate), IB-45 (sodium diisobutylsulfosuccinate), EF- 800 (sulfosuccinate sodium ethylene oxide modified half ester), A-102 (sulfosuccinate sodium ethylene oxide modified half ester), manufactured by Kao Co., Ltd. Perex OT-P (dialkylsulfate) Succinate sodium), perex CS (dialkylsulfosuccinate sodium), perex TR (dialkylsulfosuccinate sodium), perex TA (dialkylsulfosuccinate sodium), Nippon Emulsifier Co., Ltd. New Call 290-A ( Dialkylsulfosuccinate sodium), Newcol 290-KS (dialkylsulfosuccinate sodium), Newcol 291-M (di-2-ethylhexylsulfosuccinate sodium), Newcol 291-PG (Di-2- Ethylhexylsulfosuccinate sodium), Newcol 291-GL (di-2-ethylhexylsulfosuccinate sodium), Newcol 292-PG (dipolyoxyethylene-2-ethyl) Hexylsulfosuccinate sodium), Newcol 293 (monoalkylsulfosuccinate disodium), Newcol 297 (monoalkylsulfosuccinate disodium), among others, dialkylsulfosuccinate salts, Dipolyoxyethylene alkyl sulfosuccinate salts can be preferably used, and in particular, di-2-ethylhexyl sulfosuccinate salt, dihexyl sulfosuccinate salt, ditridecyl sulfosuccinate salt, dibutyl sulfosuccinate A salt, dipolyoxyethylene-2-ethylhexylsulfosuccinate salt can be preferably used. It is because it can be made more excellent by the dispersion stability of the said resin by being a compound shown by the said Formula (1).

The content of the compound represented by the formula (1) is not particularly limited as long as it can improve the dispersion stability of the resin. For example, 0.005% by mass in the ink It is preferable that the content be 0.01% by mass or more, particularly 0.03% by mass or more. Further, the upper limit is preferably 10.0% by mass or less, and more preferably 5.0% by mass or less, and particularly preferably 3.0% by mass or less. This is because when the content is within the above range, the dispersion stability of the resin can be improved.

(2) Polysiloxane compound The polysiloxane compound used in the present invention improves the wetting and spreading of the ink of the present invention onto the surface of a recording medium.

As such a polysiloxane compound, a compound having a polysiloxane bond (—Si—O—Si—) as a main skeleton, specifically, a compound having a siloxane structural unit represented by the following formula (2): It is not particularly limited.

(In Formula (2), R ³ and R ⁴ are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or a phenyl group. P is an integer of 2 or more.)

In the present invention, R ³ and R ⁴ are not particularly limited as long as they are a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or a phenyl group, but in particular, they are alkyl groups having 1 to 4 carbon atoms. In particular, it is preferably a methyl group, that is, a polydimethylsiloxane compound. This is because the polydimethylsiloxane compound has a high surface tension reducing effect and a high effect of improving the wetting and spreading of the ink.
Further, p is not particularly limited as long as p is an integer of 2 or more, but it is preferably in the range of 2 to 10,000, and more preferably in the range of 2 to 2000. It is because it can have the outstanding surface tension reduction effect by having the structure of the said repeating number.

The polysiloxane compound is not particularly limited as long as it has the siloxane structural unit, but is preferably a polyether group-modified polysiloxane compound. It is because it is easy to make a polysiloxane compound water-soluble by having the said polyether group.

Examples of the polyether group include an alkylene oxide-containing group. Among them, an ethylene oxide-containing group and a propylene oxide-containing group are preferable, and an ethylene oxide-containing group is particularly preferable. It is because it is easy to make it water-soluble by being the said polyether group.

The polyether group-modified polysiloxane compound is not particularly limited as long as it has the above polyether group. For example, one end or both ends of a polysiloxane structure or a polysiloxane structure A side chain, that is, a polyether group-containing structural unit in which any of R ³ and R ^{4 in} the siloxane structural unit is substituted with a polyether group may be used.
More specifically, a dimethylsiloxane structural unit R ³ and R ⁴ are methyl groups, one of R ³ and R ⁴ is a methyl group, a polyether group containing the structural unit and the other is a polyether group Examples thereof include polyether group-modified polydimethylsiloxane compounds.

The weight average molecular weight of the polysiloxane compound is not particularly limited as long as it can have a desired wetting and spreading property, but is preferably in the range of 300 to 60,000. However, it is preferably in the range of 500 to 30000, and particularly preferably in the range of 1000 to 15000. This is because when the molecular weight is within the above-described range, the wet spreadability can be improved.

The polysiloxane compound is preferably water-soluble. This is because, by being water-soluble, it is possible to suppress the polysiloxane compound from depositing on the ink surface or from the surface of the ink jet head member, and the ink jet head from repelling ink and deteriorating the discharge performance.
Here, being water-soluble means that 0.1 part by mass or more is dissolved in 100 parts by mass of water at 25 ° C. under 1 atm.
In addition, as a method for adjusting the water solubility of the polysiloxane compound, it can be adjusted by the kind and number of the polyether groups, the molecular weight of the polysiloxane compound, and the like.

Examples of commercially available polysiloxane compounds include FZ-2122, FZ-2110, FZ-7006, FZ-2166, FZ-2164, FZ-7001, FZ-2120, SH 8400, FZ-7002, and FZ-. 2104, 8029 ADDITIVE, 8032 ADDITIVE, 57 ADDITIVE, 67 ADDITIVE, 8616 ADDITIVE (all manufactured by Toray Dow Corning), KF-6012, KF-6015, KF-6004, KF-6013, KF-6011, KF- 6043, KP-104, 110, 112, 323, 341 (all manufactured by Shin-Etsu Chemical Co., Ltd.), BYK-300 / 302, BYK-301, BYK-306, BYK-307, BYK-320, BYK- 325, BYK-330 BYK-331, BYK-333, BYK-337, BYK-341, BYK-342, BYK-344, BYK-345 / 346, BYK-347, BYK-348, BYK-349, BYK-375, BYK-377, BYK-378, BYK-UV3500, BYK-UV3510, BYK-310, BYK-315, BYK-370, BYK-UV3570, BYK-322, BYK-323, BYK-3455, BYK-Silclean3700 (all manufactured by BYK-Chemie) ), Silface SAG503A, Silface SJM-002, Silface SJM-003 (all manufactured by Nissin Chemical Industry Co., Ltd.) and the like.
In the present invention, among them, a polyether group-modified polysiloxane compound having a polyether group can be preferably used, and a water-soluble polyether group-modified polysiloxane compound can be preferably used.

The content of the polysiloxane compound is not particularly limited as long as it can have a desired wetting and spreading property. For example, it is 0.001% by mass or more in the ink. Of these, 0.01% by mass or more, particularly 0.05% by mass or more is preferable. Further, the upper limit is preferably 10.0% by mass or less, more preferably 5.0% by mass or less, and particularly preferably 3.0% by mass or less. This is because, when the content is within the above-described range, wetting and spreading of the ink is improved, and the dot diameter when the ink lands on the substrate can be increased.

The ratio of the compound represented by the formula (1) and the polysiloxane compound contained in the ink is preferably 1: 100 to 100: 1, more preferably 1:50 to 50: 1, and 1:30 to 30: 1 is more preferred. By including a polysiloxane compound in such a ratio together with the compound represented by the above formula (1) as a surfactant, it is possible to achieve an excellent balance between permeability to coated paper and wet spreadability. This is because the image clarity can be improved.
Further, the total amount of the compound represented by the above formula (1) and the polysiloxane compound is preferably 0.005% by mass or more, more preferably 0.01% by mass or more, particularly 0 in the ink. 0.05 mass% or more is preferable. Further, the upper limit is preferably 15.0% by mass or less, more preferably 10.0% by mass or less, and particularly preferably 5.0% by mass or less. It is because it can be excellent in both the said permeability and wet spread property.

(3) Others The surfactant in the present invention contains a compound represented by the above formula (1) and a polysiloxane compound, but if necessary, other than the compound represented by the above formula (1) and the polysiloxane compound. These surfactants may be included.
Such other surfactant is not particularly limited as long as it does not inhibit the action of the compound represented by the above formula (1) and the polysiloxane compound. For example, an anionic surfactant, Nonionic surfactants, fluorine-based surfactants, alkylene oxide-modified acetylene glycol-based surfactants, alkylene oxide non-modified acetylene glycol-based surfactants and the like can be mentioned.
In the present invention, it is preferable that an alkylene oxide non-modified acetylene glycol surfactant is included. This is because by including an alkylene oxide non-modified acetylene glycol surfactant as the surfactant, the wettability of the ink to the recording medium can be improved.

Examples of the alkylene oxide non-modified acetylene glycol surfactants include acetylene diol compounds and acetylene alcohol compounds that are not modified with alkylene oxide.
Here, the acetylene diol compound or acetylene alcohol compound not modified with alkylene oxide is a compound in which a hydroxyl group is bonded to carbon adjacent to an acetylene bond, and ethylene oxide or propylene oxide is not added via the hydroxyl group. Is shown.
The weight average molecular weight of the alkylene oxide non-modified acetylene glycol surfactant is not particularly limited as long as it can have a desired wettability. It is preferable to be within the range. It is because the effect of improving the wetting and spreading is high and the effect is stably obtained because of the molecular weight.

Specific examples of such alkylene oxide non-modified acetylene glycol surfactants include 2,5-dimethyl-3-hexyne-2,5-diol, 3,6-dimethyl-4-octyne-3,6. -Diol, 2,4,7,9-tetramethyl-5-decyne-4,7-diol, 3,5-dimethyl-1-hexyn-3-ol, 3-methyl-1-butyn-3-ol, Examples include 3-methyl-1-pentyn-3-ol, 3-hexyne-2,5-diol, and 2-butyne-1,4-diol.
Moreover, as a commercial item, Surfynol 61,82,104 (all are the air products company make) etc. can be used.

The content of the above-mentioned alkylene oxide non-modified acetylene glycol surfactant is not particularly limited as long as it can have a desired wetting and spreading property. It is preferably within the range of 001% by mass to 5% by mass, and more preferably within the range of 0.001% by mass to 3% by mass, and particularly within the range of 0.05% by mass to 3% by mass. It is preferable that This is because when the content is in the above-described range, the ink can be excellent in wet spreadability.

Specific examples of the anionic surfactant, nonionic surfactant, fluorine surfactant, alkylene oxide-modified acetylene glycol surfactant include Emar, Latemule, Neoperex, and Demol (all Anionic surfactant: manufactured by Kao Corporation, Sannol, Lipolane, Lipon, Lipar (all are anionic surfactant; manufactured by Lion Corporation), Neugen, Epan, Sorgen (all are nonionic surfactants; Daiichi Kogyo Seiyaku Co., Ltd.) Emulgen, Amito, Emazole (Nonionic Surfactant; Kao Co., Ltd.), Naroacty, Emalmin, Sannonic (Nonionic Surfactant: Sanyo Chemical Industries, Ltd.) Manufactured), Mega-Fac (Fluorine-based surfactant; manufactured by DIC Corporation), SA Freon (fluorine surfactant; AGC Seimi Chemical Co., Ltd.). Examples of the alkylene oxide-modified acetylene glycol surfactant include Surfynol 420, 440, 465, 485, TG, 2502, Dinol 604, 607 (all manufactured by Air Products), Surfynol SE, MD-20, Orphin E1004, E1010, PD-004, EXP4300, PD-501, PD-502, SPC (all manufactured by Nissin Chemical Industry Co., Ltd.), acetylenol EH, E40, E60, E81, E100, E200 (all Kawaken Fine Chemical Co., Ltd.).
The content of these surfactants is appropriately adjusted according to the content of the solvent, resin, pigment and other surfactants.

3. Solvent The solvent used in the present invention disperses or dissolves the above components.

Such a solvent is preferably an aqueous solvent having water solubility. It is because the effect that it can be made excellent in the dispersion stability of resin by using together with the said resin and surfactant can be exhibited more effectively.
Here, having water solubility indicates that it has a high polarity, and specifically indicates that it contains water and / or a water-soluble organic solvent.
In the present invention, water and / or a water-soluble organic solvent is preferably contained in the solvent in an amount of 50% by mass or more, particularly preferably 70% by mass or more, and in particular, 80% by mass. It is preferable to include the above. This is because the effect that the resin can have excellent dispersion stability can be more effectively exhibited.

The water-soluble organic solvent in the present invention can be dissolved in 5 parts by mass or more at 1 atm in 100 parts by mass of water at 25 ° C.
Examples of such water-soluble organic solvents include methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, sec-butyl alcohol, tert-butyl alcohol, isobutyl alcohol, and n-pentanol. Alkyl alcohols having 1 to 5 carbon atoms; monovalent such as 3-methoxy-3-methyl-1-butanol, 3-methoxy-1-propanol, 1-methoxy-2-propanol, 3-methoxy-n-butanol Alcohols: 1-dimethylformamide, dimethylacetamide, 3-methoxypropanamide, 3-butoxypropanamide, N, N-dimethyl-3-methoxypropanamide, N, N-dibutyl-3-methoxypropanamide, N, N -Dibutyl-3-butoxyp Amides such as panamide and N, N-dimethyl-3-butoxypropanamide; ketones or ketoalcohols such as acetone and diacetone alcohol; ethers such as tetrahydrofuran and dioxane; oxyethylene or oxy such as polyethylene glycol and polypropylene glycol Propylene copolymer; ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, 1,3-propanediol, isobutylene glycol, triethylene glycol, tripropylene glycol, tetraethylene glycol, 1,2-butanediol, 1,3- Butanediol, 1,4-butanediol, 1,2-pentanediol, 1,2-hexanediol, 1,5-pentanediol, 1,6-hexanediol Diols such as 2-methyl-2,4-pentanediol, 3-methyl-1,3-butanediol, 3-methyl-1,5-pentanediol; glycerin, trimethylolethane, trimethylolpropane, 1, Triols such as 2,6-hexanetriol: tetrahydric alcohols such as mesoerythritol and pentaerythritol; ethylene glycol monomethyl (or ethyl, isopropyl, n-butyl, isobutyl, n-hexyl, 2-ethylhexyl) ether, diethylene glycol monomethyl (Or ethyl, isopropyl, n-butyl, isobutyl, n-hexyl, 2-ethylhexyl) ether, triethylene glycol monomethyl (or ethyl, isopropyl, n-butyl, isobutyl) ether, propylene glycol Monoalkyl ethers such as monomethyl (or ethyl, isopropyl, n-butyl, isobutyl) ether, dipropylene glycol monomethyl (or ethyl, isopropyl, n-butyl, isobutyl) ether; diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol ethyl methyl ether , Dialkyl ethers of polyhydric alcohols such as triethylene glycol dimethyl ether, triethylene glycol diethyl ether, tetraethylene glycol dimethyl ether, tetraethylene glycol diethyl ether, propylene glycol dimethyl ether, propylene glycol diethyl ether, dipropylene glycol dimethyl ether, dipropylene glycol diethyl ether Alkanolamines such as monoethanolamine, diethanolamine, triethanolamine, N-methylethanolamine, N-ethylethanolamine, N-butylethanolamine, N-methyldiethanolamine, N-ethyldiethanolamine, N-butyldiethanolamine Nitrogen-containing heterocyclic compounds such as N-methyl-2-pyrrolidone, 2-pyrrolidone and 1,3-dimethyl-2-imidazolidinone; cyclic compounds such as γ-butyrolactone and sulfolane;

In the present invention, when the solvent includes a water-soluble organic solvent, the water-soluble organic solvent preferably includes those having a boiling point higher than that of water, that is, those having a boiling point higher than 100 ° C. Preferably include those having a boiling point of 180 ° C. or higher. Ink adhering to the nozzle and the water-soluble organic solvent in the ink volatilize in the fine tube inside the ink-jet head, and the viscosity of the ink can be suppressed. The nozzle and tube are clogged and the ink-jet head is damaged. This is because it can be prevented. Further, as a result, it is possible to obtain an ink having good fluidity and good continuous ejection properties and ejection properties after being left.
Also, when the boiling point of the solvent is high, drying requires a lot of energy or it takes a long time to dry, so it is difficult to support high-speed continuous printing. It is preferable that it is 300 degreeC.
The water-soluble organic solvent having a boiling point higher than that of water as described above may be 50% by mass or more, more preferably 70% by mass or more, and particularly preferably 80% by mass or more in all the water-soluble organic solvents.

In the present invention, when the solvent contains a water-soluble organic solvent, 50% by mass or more of the total water-soluble organic solvent contained in the solvent is 50% by mass aqueous solution viscosity (V50) and 20% by mass aqueous solution viscosity (V20). The ratio V50 / V20 is preferably a water-soluble organic solvent in the range of 2.0 to 3.6, and more preferably in the range of 2.0 to 3.2. By containing 50% by mass or more of the water-soluble organic solvent having a viscosity ratio in the above-mentioned range of the total water-soluble organic solvent, the ink viscosity after the water in the ink attached to the nozzles volatilizes increases rapidly. This is because the ink can be suppressed, the fluidity is good, and the continuous ejection property and the ejection property after being left are good. More preferably, the water-soluble organic solvent having a viscosity ratio in the above-mentioned range is 70% by mass or more, particularly preferably 80% by mass or more in all the water-soluble organic solvents.
In addition, it is widely known that the viscosity of the ink has a great influence on the ink jet discharge performance. For example, in order to make the ink viscosity within the discharge suitable viscosity range of the ink jet head, solid materials such as coloring materials and resins in the ink In general, the content is adjusted depending on the component, the content of the solvent, and the like (for example, paragraph (0030) of JP-A-2007-161923). Further, dipropylene glycol, tripropylene glycol, 3-methyl 1,3-butanediol, trimethylolpropane, trimethylolethane, which have been used in the inks proposed so far, such as JP-A No. 2003-268268 , 1,2,6-hexanetriol, diglycerin, and other inks containing a large amount of solvents with V50 / V20 greater than 3.6, the ink viscosity after the water in the ink attached to the nozzles volatilizes rapidly This is because the fluidity of the ink deteriorates and the discharge may deteriorate.

The viscosity measurement method is not particularly limited as long as the viscosity can be accurately measured. For example, a method using a viscosity measuring device such as a rheometer, a B-type viscometer, a capillary viscometer, etc. Is mentioned. The capillary viscosity measurement method can be performed according to the method described in DIN 53015 or ISO / DIS 12058. More specifically, a capillary viscometer “AMVn” (trade name) manufactured by Anton Paar can be used as a measuring device, and measurement can be performed at a measurement temperature of 25 ° C.

Examples of the water-soluble organic solvent satisfying V50 / V20 in the range of 2.0 to 3.6 include, for example, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, 1,2-butanediol, 1,2- Examples include hexanediol, 1,2-pentanediol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 3-methoxy-3-methyl-1-butanol, and glycerin. .

The water contained in the solvent does not contain various ions, and it is preferable to use deionized water.

The water content is not particularly limited as long as it can disperse or dissolve the above components, but is preferably in the range of 10% by mass to 95% by mass in the solvent. In particular, it is preferably in the range of 20% by mass to 95% by mass, particularly preferably in the range of 30% by mass to 90% by mass.
Further, the content of the water-soluble organic solvent is preferably in the range of 5% by mass to 90% by mass in the solvent, and more preferably in the range of 5% by mass to 80% by mass, In particular, it is preferably in the range of 10% by mass to 70% by mass.
This is because, when the content of the water and the water-soluble organic solvent is within the above-described range, the moisture retention is sufficient and nozzle clogging or the like can be reduced. Moreover, it is because it can make it easy to discharge by an inkjet head.

The content of the solvent is not particularly limited as long as it can have a desired ejection property. For example, the solvent is used so that the solid content concentration of the ink is 0.1% by mass to 50% by mass. In particular, it is preferably contained so as to be 1% by mass to 40% by mass. This is because when the content is within the above-described range, the discharge property can be excellent.
The solid content indicates all components other than the solvent in the ink.

4). Pigment As the pigment in the present invention, those generally used for ink can be used, and examples thereof include inorganic pigments and organic pigments.
These may be used alone or in combination of two or more.

Specific organic pigments include, for example, insoluble azo pigments, soluble azo pigments, derivatives from dyes, phthalocyanine organic pigments, quinacridone organic pigments, perylene organic pigments, dioxazine organic pigments, nickel azo pigments, isoindolinones. Organic pigments, pyranthrone organic pigments, thioindigo organic pigments, condensed azo organic pigments, benzimidazolone organic pigments, quinophthalone organic pigments, isoindoline organic pigments, quinacridone solid solution pigments, perylene solid solution pigments, etc. Examples of solid solution pigments and other pigments include carbon black.
When organic pigments are exemplified by color index (CI) numbers, C.I. I. Pigment Yellow 1, 2, 3, 12, 13, 14, 16, 17, 20, 24, 73, 74, 75, 83, 93, 95, 97, 98, 109, 110, 114, 117, 120, 125, 128, 129, 130, 137, 138, 139, 147, 148, 150, 151, 153, 154, 155, 166, 168, 180, 185, 213, 214; I. Pigment Red 5, 7, 9, 12, 48, 49, 52, 53, 57, 97, 112, 122, 123, 149, 168, 177, 180, 184, 192, 202, 206, 209, 215, 216, 217, 220, 223, 224, 226, 227, 228, 238, 240, 254; I. Pigment orange 16, 36, 43, 51, 55, 59, 61, 64, 71; C.I. I. Pigment violet 19, 23, 29, 30, 37, 40, 50; C.I. I. Pigment Blue 15, 15: 1, 15: 3, 15: 4, 15: 6, 16, 22, 60, 64; C.I. I. Pigment green 7, 36, 58; I. Pigment brown 23, 25, 26, and the like.

Specific examples of the inorganic pigment include barium sulfate, iron oxide, zinc oxide, barium carbonate, barium sulfate, silica, clay, talc, titanium oxide, calcium carbonate, synthetic mica, alumina, zinc white, lead sulfate, yellow lead, Examples include zinc yellow, red bean (red iron oxide (III)), cadmium red, ultramarine blue, bitumen, chromium oxide green, cobalt green, amber, titanium black, synthetic iron black, and inorganic solid solution pigments.

The average dispersed particle diameter of the pigment is not particularly limited as long as the desired color can be developed. It varies depending on the type of pigment used, but the pigment has good dispersion stability and sufficient coloring power. From the viewpoint of obtaining, it is preferably in the range of 5 nm to 200 nm, and more preferably in the range of 30 nm to 150 nm. If the average dispersed particle size is not more than the above upper limit, nozzle clogging of the inkjet head is unlikely to occur, a homogeneous image with high reproducibility can be obtained, and the resulting printed matter can be of high quality. Because. It is because light resistance may fall when it is below said lower limit.

The content of the pigment is not particularly limited as long as a desired image can be formed, and is appropriately adjusted. Specifically, although it varies depending on the type of pigment, it is preferably in the range of 0.05% by mass to 20% by mass in the ink, and preferably in the range of 0.1% by mass to 10% by mass. preferable. This is because, when the content is within the above-described range, it is possible to achieve an excellent balance between pigment dispersion stability and coloring power.

Further, the pigment in the present invention is a pigment dispersion in which the pigment is dispersed in an aqueous solvent with the surfactant or dispersant for dispersing the pigment, or a self-dispersion in which the hydrophilic surface is directly modified on the pigment surface. It may be included as a pigment dispersion as a type pigment.
As such a self-dispersing pigment, for example, as a hydrophilic group, a carbonyl group, a carboxyl group, a hydroxyl group, a sulfonic acid group, and at least one PO or the like described in JP 2012-51357 A can be used. Examples thereof include those modified with a phosphorus-containing group having a P═O bond. Examples of commercially available products include “CAB-O-JET (registered trademark) 200”, “CAB-O-JET (registered trademark) 250C”, “CAB-O-JET (manufactured by Cabot Specialty Chemicals) (Registered trademark) 260M "," CAB-O-JET (registered trademark) 270Y "," CAB-O-JET (registered trademark) 300 "," CAB-O-JET (registered trademark) 400 "," CAB-O- " JET (registered trademark) 450C "," CAB-O-JET (registered trademark) 465M "," CAB-O-JET (registered trademark) 470Y "," CAB-O-JET (registered trademark) 480V ", CAB-O -JET (registered trademark) 740Y ";" Microjet black 162, Aqua-Black 001 "," BONJET ( "Registered trademark" BLACK CW-1 "" BONJET (registered trademark) BLACK CW-2 "and" BONJET (registered trademark) BLACK CW-3 ";" LIOJET (registered trademark) WD BLACK 002C "manufactured by Toyo Ink Mfg. Co., Ltd. Etc.

As the dispersant, those generally used for ink can be used. Specifically, cationic, anionic, nonionic, amphoteric, silicone (silicon), fluorine-based surfactants described in JP 2012-51357 A and the like can be used. Among these, a polymer surfactant (polymer dispersant) can be preferably used. Commercially available products include “SMA1440” manufactured by SARTOMER (styrene-maleic acid-maleic ester polymer dispersant, weight average molecular weight 7,000, acid value 185 mg KOH / g), “Joncrill 682” manufactured by BASF Japan (styrene) -Acrylic acid polymer dispersant (weight average molecular weight 1,700, acid value 238 mgKOH / g), "RY72" (styrene-acrylic acid-acrylic acid ester polymer dispersant, weight average molecular weight 14,800, manufactured by Gifu Shellac Co., Ltd.) And acid value 170 mgKOH / g).

5. Ink composition for inkjet recording The ink of the present invention comprises a resin, a surfactant, a pigment, and a solvent, but may further contain other components as necessary.
Examples of other components include penetrants, wetting agents, preservatives, antioxidants, conductivity adjusting agents, pH adjusting agents, viscosity adjusting agents, antifoaming agents, and oxygen scavengers.

The method for preparing the ink of the present invention is not particularly limited as long as the above components can be dispersed or dissolved in a solvent.
For example, after adding and dispersing a self-dispersing pigment in a solvent, a method of preparing by adding a resin, a surfactant, and other components as necessary, a pigment and a dispersant are added to the solvent and dispersed, A method of preparing by adding a resin, a surfactant and other components as required, and a method of adding a pigment, a resin, a surfactant and other components to a solvent, and then dispersing and preparing the pigment The method etc. can be mentioned.

The surface tension of the ink of the present invention is not particularly limited as long as it can be ejected from the inkjet head, and varies depending on the type of recording medium used and the type of inkjet head. For example, when the recording medium is non-coated paper, the paper has high absorbability, and therefore printing is possible within the range of 20 mN / m to 50 mN / m.
On the other hand, when the recording medium has low absorbency such as coated paper, it is preferably within the range of 20 mN / m to 35 mN / m, and within the range of 20 mN / m to 32 mN / m. Is preferable, more preferably in the range of 20 mN / m to 30 mN / m, still more preferably in the range of 20 mN / m to 28 mN / m.
Due to the above upper limit, ink is difficult to absorb and repels on the surface, so even when using coated paper where the dots do not spread easily, wetting spreads on the coated paper surface, spreading the dots and forming a clear image Because it becomes possible to do. Moreover, it is because the discharge stability of the ink from an inkjet head can be made favorable because it is the said minimum.
The surface tension in the present invention is a value measured by the Wilhelmy method (Kyowa Interface Science model: CBVP-Z) at a measurement temperature of 25 ° C.

The method of printing using the ink of the present invention is not particularly limited as long as it is a method of printing by an ink jet method.
As such an ink jet method, any one of a piezo method, a thermal method, an electrostatic method, and the like may be used. Among them, a piezo method is preferable because aggregates hardly occur and discharge stability is excellent. The inkjet method is preferred.
Note that a piezoelectric inkjet head (recording head) uses a piezoelectric vibrator as a pressure generating element, and discharges ink droplets by pressurizing and depressurizing a pressure chamber by deformation of the piezoelectric vibrator.

B. Ink set for ink jet recording Next, the ink set for ink jet recording of the present invention will be described.
The ink set of the present invention contains the above-mentioned ink, contains two or more of the above-mentioned inks, the surface tension of the above-mentioned ink is in the range of 20 mN / m to 30 mN / m, and the surface tension between all the above-mentioned inks Can be divided into two modes: a mode (first mode) in which the difference is 1 mN / m or less, and a mode (second mode) having the ink and a receiving solution containing a polyvalent metal salt.
Hereinafter, the ink set of the present invention will be described for each aspect.

1. First Aspect The ink set of this aspect includes two or more of the inks, the surface tension of the ink is in the range of 20 mN / m to 30 mN / m, and the difference in surface tension between all the inks is 1 mN / m. It is characterized by the following.
Including two or more of the above-mentioned inks means having two or more of the above-mentioned inks independently, and usually having two or more of the above-mentioned inks of different colors.

According to this aspect, since the surface tension of the ink has the above-described relationship, bleeding between different colors (between inks) is small, and the image can have excellent image clarity.

The ink set of this embodiment includes the above ink.
Hereinafter, each component of the ink set of this embodiment will be described in detail.
The ink can be the same as that described in the section “A. Ink composition for ink jet recording”, and the description thereof is omitted here.

The difference in surface tension between all the inks included in the ink set of this embodiment is not particularly limited as long as it is 1 mN / m or less, but is preferably 0.8 mN / m or less, especially 0 It is preferably 6 mN / m or less. When the difference in surface tension between the inks is within the above-described range, even when the inks applied to adjacent portions are in contact with each other, they can be effectively prevented from mixing, and different colors (inks This is because there is less bleeding between the two.

The number of inks contained in the ink set is not particularly limited as long as it is 2 or more, and can be 3 or 4, for example.
The ink colors included in the ink set include combinations of red, blue, yellow and black, and combinations of clear, light magenta, light cyan, light black, violet, orange, green, magenta, white ink, etc. It can be.

The recording method for printing using the ink set of the present embodiment is not particularly limited as long as it can form a desired image by an inkjet method using two or more of the above-described inks. It is preferable that the ink is ejected so that two or more of the inks are in contact with each other. This is because it is possible to more effectively exhibit the effect of reducing the bleeding between different colors (between inks).
The ink jet method can be the same as that described in the section “A. Ink composition for ink jet recording”.

The recording medium printed using the ink set of this aspect is not particularly limited as long as it can be printed using the ink set, and either an absorber or a non-absorber can be used. it can. Absorbents include non-coated paper such as modified paper, medium-quality paper, and high-quality paper, coated paper such as coated paper, art paper, and cast paper, cotton, synthetic fabric, silk, hemp, fabric, nonwoven fabric, leather, etc. Examples of non-absorbent substrates that are non-absorbents include polyester resins, polypropylene synthetic paper, vinyl chloride resins, polyimide resins, metals, metal foil coated paper, glass, synthetic rubber, natural rubber, etc. Although it can illustrate, it is not limited to these.
In this embodiment, it is particularly preferable to use coated paper. This is because the effects of the present invention can be more effectively exhibited by using the ink.

2. Second Aspect The ink set according to the present aspect includes the above ink and a receiving solution containing a polyvalent metal salt.

According to this aspect, when used together with the above-described receiving solution, bleeding between the printed portion and the non-printed portion and between different colors (between inks) is small, and the image clarity can be improved. .

The ink set according to this aspect includes the above ink and a receiving solution.
Hereinafter, each component of the ink set of this embodiment will be described in detail.
The ink can be the same as that described in the section “A. Ink composition for ink jet recording”, and the description thereof is omitted here.

(1) Receiving solution The receiving solution used in this embodiment contains a polyvalent metal salt.

(A) Multivalent metal salt The polyvalent metal salt is not particularly limited as long as it improves the fixability of the ink on the recording medium. It is not particularly limited as long as it is a divalent or higher-valent metal salt composed of an anion, and may be an inorganic metal salt or an organic acid metal salt. Such a polyvalent metal salt is preferably at least one selected from the group consisting of calcium salts, magnesium salts, nickel salts, aluminum salts, boron salts and zinc salts. This is because ink bleeding and color bleeding between different colors (between inks) can be suppressed, and an image having excellent image sharpness without printing unevenness or white spots can be obtained.
In addition, the said bivalent or more metal salt may be used individually by 1 type, or may be used in combination of 2 or more type.
Further, as the inorganic metal salt and organic acid metal salt, those described in JP 2012-51357 A can be specifically used.

(B) Receiving solution The receiving solution contains the polyvalent metal salt, but usually contains a solvent, a resin component, and a surfactant.
Moreover, you may have a penetrating agent, antiseptic | preservative, antioxidant, an electrical conductivity modifier, a pH adjuster, a viscosity modifier, an antifoamer, a deoxidizer, etc. as needed.
As the surfactant, the same surfactants as those described in the section “A. Ink composition for inkjet recording” can be used.
As the solvent, resin component, and other additives, those generally used for receiving solutions can be used, for example, those described in JP 2012-51357 A.

The surface tension of the receiving solution is not particularly limited as long as it can stably adhere to the recording medium. For example, it is described in the above section “A. Ink composition for inkjet recording”. It can be the same as the surface tension of the ink.
The surface tension of the receiving solution can be adjusted by appropriately selecting the solvent and the surfactant.

(2) Ink set The ink set of this aspect includes the ink and the receiving solution.

When the ink in this embodiment includes two or more of the above-described inks, the difference in surface tension between all the inks is not particularly limited as long as a desired printed matter can be produced. This can be the same as that described in “1. First embodiment”.

The recording method for printing by the ink jet method using the ink set of the present embodiment is not particularly limited as long as a desired printed matter can be produced, but a receiving solution for forming a receiving solution layer on a recording medium. A recording method having an application step and an ink application step of applying the ink onto the receiving solution layer can be exemplified.
The ink jet method can be the same as that described in the section “A. Ink composition for ink jet recording”.

The receiving solution coating step is a step of forming a receiving solution layer on the recording medium.
The method for forming the receiving solution layer on the recording medium is not particularly limited as long as the receiving solution layer can be formed before the ink application step is performed, and a spray method, a coater method, an ink jet method, and the like. And a method using a gravure method and a flexo method.
In the present invention, among these, a method of forming a receiving solution layer using an ink jet method is preferable. Before the solvent contained in the receiving solution layer is completely dried, it is easy to perform the ink application step, and the ink on the recording medium can be quickly reacted with the polyvalent metal salt contained in the receiving solution. This is because it is possible to easily improve the fixing property.

The amount of the receiving solution applied may be such that the amount of the polyvalent metal salt attached to the recording medium is in the range of 20 μmol / cm ² to 2000 μmol / cm ² .

The ink application step is a step of applying the ink onto the receiving solution layer.
The method for applying the ink on the receiving solution layer is not particularly limited as long as it is a method using an ink jet method, but it is applied before the solvent contained in the receiving solution layer is completely dried. It is preferable. This is because there is no color unevenness or white spots, and feathering and color bleeding can be suppressed. Further, it is possible to reduce the process and time for drying the receiving solution attached to the printing surface, and it can be suitably used for mass printing and high-speed printing.

The ink jet method and the recording medium can be the same as those described in the section “1. First aspect”.

C. Inkjet recording method The inkjet recording method of the present invention is characterized by printing by the inkjet method using the above-described ink set or ink set.

According to the present invention, by using the above ink or ink set, a printed matter excellent in water resistance, solvent resistance and image sharpness can be produced.

The ink jet recording method of the present invention uses the above ink or ink set.
Such an ink or ink set is the same as that described in the sections of “A. Ink composition for ink jet recording” and “B. Ink set for ink jet recording”. Omitted.
In addition, the method of printing by the ink jet method using the ink or ink set is the same as that described in the above sections “A. Ink composition for ink jet recording” and “B. Ink set for ink jet recording”. Explanation here is omitted.

The present invention is not limited to the above embodiment. The above-described embodiment is an exemplification, and the present invention has substantially the same configuration as the technical idea described in the claims of the present invention, and any device that exhibits the same function and effect is the present invention. It is included in the technical scope of the invention.

[Examples 1 to 19 and Comparative Examples 1 to 9]
1. Preparation of Pigment Dispersion (1) Preparation of Pigment Dispersion P-1 (Black) Kieczykowski et al., J. Org. Chem., 1995, Vol. 60, P.8310-831 and U.S. Pat. No. 4,922,2007 A procedure similar to that shown was used to prepare [2- (4-aminophenyl) -1-hydroxyethane-1,1-diyl] bisphosphonic acid-sodium salt. First, a 500 mL three-necked flask was equipped with a condenser with a gas outlet at the top of the condenser, a thermometer and dry nitrogen inlet, and a 100 mL pressure equalizing addition funnel. To this flask was initially added 32 g phosphorous acid (380 mmol) and 160 mL methanesulfonic acid (solvent). To this stirred mixture, 57.4 g of aminophenylacetic acid (380 mmol) was added in portions. The stirred mixture was heated to 65 ° C. for 1-2 hours to completely dissolve the solids. The entire system was flushed with dry nitrogen and the temperature was reduced to 40 ° C. after all of the solids had dissolved. To this heated solution 70 mL of PCl ₃ (800 mmol) was slowly added through an addition funnel. HCl gas generated by the reaction was discharged through a gas outlet. After the addition was complete, the reaction mixture was stirred for 2 hours and heated at 40 ° C. The temperature was then raised to 65-70 ° C. and the mixture was stirred overnight. The resulting clear brown solution was cooled to room temperature and quenched by addition into a 600 g ice / water mixture.
This aqueous mixture was placed in a 1 L beaker and heated to 90-95 ° C. for 4 hours (the top of the beaker was covered with a glass plate). The mixture was then cooled to room temperature and the pH of the mixture was adjusted to 4-5 with 50% NaOH solution. The mixture is cooled in an ice bath to 5 ° C. for 2 hours, then the resulting solid is collected by suction filtration, washed with 1 L of cold deionized water, dried at 60 ° C. overnight, white or off-white color Of a solid product (yield: 48 g, yield: 39%). ¹ H-NMR data (D ₂ O / NaOH) of the obtained solid product was as follows. That is, 7.3 (2H, d), 6.76 (2H, d), 3.2 (2H, t). The ¹³ C-NMR data (D ₂ O / NaOH) of the obtained solid product were 141, 130, 128, 112, and 73, respectively.

20 g of carbon black (Black Pearls (registered trademark) 700 carbon black (manufactured by Cabot)), 20 mmol of the above solid product, 20 mmol of nitric acid, and 200 mL of deionized water were mixed at room temperature with a Silverson mixer (6000 rpm). Mixed. After 30 minutes, sodium nitrite (20 mmol) dissolved in a small amount of water was slowly added into the mixture. The temperature reached 60 ° C. by mixing and was allowed to proceed for 1 hour. As a result, self-dispersed pigments (including pigments in which at least two phosphonic acid groups or salts thereof are bonded) in which the solid product is modified to carbon black were generated. The pH is adjusted to 8-9 with NaOH solution, and after 30 minutes, the dispersion with the self-dispersing pigment is diafiltered with a spectrum membrane using 20 parts by volume of deionized water, Concentration to a solid content of 15% by mass gave a pigment dispersion P-1 (black).

(2) Preparation of Pigment Dispersion P-1 (Blue), Pigment Dispersion P-1 (Yellow), and Pigment Dispersion P-1 (Red) Instead of carbon black, C.I. I. Pigment blue 15: 4 (PB15: 4), C.I. I. Pigment yellow 74 (PY74), C.I. I. Pigment dispersion P-1 (blue) and pigment dispersion P- were prepared in the same manner as in “(1) Preparation of pigment dispersion P-1 (black)”, except that CI Pigment Red 122 (PR122) was used. 1 (yellow) and pigment dispersion P-1 (red) were obtained.

(3) Preparation of Pigment Dispersion P-4 (Black) To 80.1 g of ion exchange water, a styrene-acrylic acid polymer dispersant (“Joncrill 682” manufactured by BASF Japan Ltd., weight average molecular weight 1,700, acid value) 238mgKOH / g) 3.0g and triethanolamine 1.8g, 15g of carbon black and 0.1g of anti-foaming agent ("Surfinol 104E" manufactured by Air Products) are added and paint using zirconia beads. Dispersion was carried out using a shaker to obtain a pigment dispersion P-4 (black). The styrene-acrylic acid polymer dispersant is not an emulsion and has a different property from the low acid value resin in the present invention.

(4) Preparation of Pigment Dispersion P-4 (Blue), Pigment Dispersion P-4 (Yellow), and Pigment Dispersion P-4 (Red) Instead of carbon black, PB15: 4, PY74, and PR122 were used. Pigment dispersion P-4 (blue), pigment dispersion P-4 (yellow), and pigment dispersion were the same as in “(3) Preparation of pigment dispersion P-4 (black)” except that each was used. Body P-4 (red) was obtained.

2. Preparation of Resin Emulsion A resin emulsion was prepared by the following method. The average particle size of the obtained resin emulsion was measured at 25 ° C. using a dense particle size analyzer (manufactured by Otsuka Electronics Co., Ltd., model: FPAR-1000).

After sufficiently replacing the inside of the flask equipped with a mechanical stirrer, thermometer, nitrogen gas introduction tube, reflux tube and dropping funnel with nitrogen gas, a reactive surfactant (trade name: Latemul PD-, manufactured by Kao Corporation) 104) 0.75 g, potassium persulfate 0.04 g, methacrylic acid 1.2 g and pure water 150 g were charged and stirred at 25 ° C. and mixed. A mixture of 15 g of styrene, 88.5 g of methyl methacrylate and 45 g of 2-ethylhexyl acrylate was added dropwise thereto to prepare a pre-emulsion. Also, after sufficiently replacing the inside of the flask equipped with a mechanical stirrer, thermometer, nitrogen gas inlet tube, reflux tube and dropping funnel with nitrogen gas, a reactive surfactant (trade name: Latemul manufactured by Kao Corporation) PD-104) 3 g, potassium persulfate 0.01 g and pure water 200 g were stirred and mixed at 70 ° C. Thereafter, the prepared pre-emulsion was dropped into the flask over 3 hours. After further aging at 70 ° C. for 3 hours, the mixture was cooled, adjusted to pH 8 with an aqueous ammonia solution, filtered through # 150 mesh (manufactured by Nippon Textile), and 500 g of resin emulsion R-2 (solid content 30 mass) %).
Resin emulsions R-1, R-3, R-4, and R-8 were also synthesized by adjusting the monomer composition as described below by the same synthesis method as that for resin emulsion R-2.
R-1: 0.8 g of methacrylic acid, 141 g of methyl methacrylate, 8.2 g of 2-ethylhexyl acrylate
R-3: 0.2 g of methacrylic acid, 135 g of methyl methacrylate, 15 g of 2-ethylhexyl acrylate
R-4: 3 g of methacrylic acid, 120 g of methyl methacrylate, 27 g of 2-ethylhexyl acrylate
R-8: 6 g of methacrylic acid, 84 g of methyl methacrylate, 45 g of 2-ethylhexyl acrylate, 15 g of 4-hydroxybutyl acrylate

The obtained resin emulsion R-1 had a glass transition temperature of 85 ° C., an acid value of 3 mgKOH / g, a hydroxyl value of 0 mgKOH / g, and a particle size of 110 nm. Resin emulsion R-2 had a glass transition temperature of 18 ° C., an acid value of 8 mgKOH / g, a hydroxyl value of 0 mgKOH / g, and a particle size of 120 nm. Resin emulsion R-3 had a glass transition temperature of 70 ° C., an acid value of 1 mgKOH / g, a hydroxyl value of 0 mgKOH / g, and a particle size of 105 nm. Resin emulsion R-4 had a glass transition temperature of 48 ° C., an acid value of 13 mgKOH / g, a hydroxyl value of 0 mgKOH / g, and a particle size of 130 nm.
Also. R-8 had a glass transition temperature of -2 ° C, an acid value of 26 mgKOH / g, a hydroxyl value of 39 mgKOH / g, and a particle size of 160 nm.

3. Preparation of ink According to the composition described in Table 1 below, a pigment dispersion, a resin emulsion, a surfactant, and a water-soluble organic solvent are mixed, and water (ion-exchanged water) is added to make the total amount 100 parts by weight. (Examples 1 to 16 and Comparative Examples 1 to 9) were obtained.
In addition, the numerical values of the pigment dispersion, the resin emulsion, and the surfactant in Table 1 indicate parts by weight of the solid content of each component. In Examples 1 to 16 and Comparative Examples 1 to 9, a black pigment dispersion was used.

As pigment dispersions in Table 1, in addition to the above pigment dispersions, P-2 (black): carbonyl group-containing self-dispersion pigment, Cab-O-Jet300 manufactured by Cabot Corporation, P-3 (black): sulfonyl group Contains self-dispersing pigment, Cab-O-Jet200 manufactured by Cabot Corporation.
As the resin emulsion, in addition to the above resin emulsion, R-5: Tg 50 ° C., acid value 98 mgKOH, styrene acrylic resin emulsion, BASF's Jonkrill 1535, R-6: Tg 90 ° C., acid value 30 mg KOH, styrene acrylic resin emulsion , BASF Jonkrill 790, and R-7: Tg 0 ° C., acid value 100 mg KOH, styrene acrylic resin emulsion, BASF Jonkrill 711.
As water-soluble organic solvents, PG: propylene glycol (V50 / V20 = 2.87), 13PD: 1,3-propanediol (V50 / V20 = 2.70), DEG: diethylene glycol (V50 / V20 = 2.2. 65), 12PD: 1,2-pentanediol (V50 / V20 = 2.65), GLY: glycerin (V50 / V20 = 3.02), DGL: diglycerin (V50 / V20 = 4.15), DPG: Dipropylene glycol (V50 / V20 = 3.64), IPG: 3 methyl 1,3 butanediol (V50 / V20 = 3.97) is used.

As compounds represented by the above formula (1), A-1: New Coal 291PG (manufactured by Nippon Emulsifier Co., Ltd., dioctylsulfosuccinate sodium salt) and A-2: New Coal 292PG (manufactured by Japan Emulsifier Co., Ltd.) Dipolyoxyethylene octylsulfosuccinate sodium salt).
As the polysiloxane compound, B-1: Silface SAG503A (manufactured by Nissin Chemical Industry Co., Ltd., water-soluble polyether-modified polysiloxane compound), B-2: BYK348 (manufactured by BYK Chemie, water-soluble polyether-modified) Polysiloxane compound).
Further, as other surfactants, C-1: Surfynol 104PG: (produced by Air Products, acetylenic diol compound), D-1: Emar 20C (polyoxyethylene lauryl ether sodium sulfate) and D-2: Dynol 607 (acetylene glycol compound) is used.

4). Evaluation Method (1) Ink Evaluation With respect to the inks obtained in Examples 1 to 16 and Comparative Examples 1 to 9, storage stability, ejection stability, ejection recovery properties, water resistance, solvent resistance, coating properties, and image clarity The sex was evaluated. The evaluation criteria are shown below. The evaluation results are shown in Table 1 below.
Note that coated paper (manufactured by Oji Paper Co., Ltd., mirror coat platinum) was used as the recording medium.

(Storage stability)
A: Sealed in a glass bottle and the change in surface tension after storage at 60 ° C. for 2 weeks is 1.0 mN / m or less, and no gelation occurs.
B: Sealed in a glass bottle and the change in surface tension after storage at 60 ° C. for 2 weeks is 1.0 mN / m or more, or gelation occurs.
A practical range is A in which changes in ink physical properties (surface tension, viscosity, etc.) are small even after long-term storage and storage stability is good.

(Discharge stability)
The ejection stability was evaluated using a printer equipped with a 720 dpi inkjet head.
A: No non-ejection nozzle even when 100 or more continuous prints are made.
B: A non-ejection nozzle occurs when the number of continuous prints is less than 100.
C: No ejection nozzles are not lost at the initial filling stage.
A and B are practical ranges.

(Discharge recovery)
After discharging from all nozzles with a printer equipped with a 720 dpi inkjet head, the number of cleanings was evaluated until the nozzles could discharge after being left at 25 ° C. for 1 hour. As a cleaning method, an operation of wiping the nozzle surface with a non-woven fabric adhered with ion exchange water was performed.
A: Ejected from all nozzles without cleaning.
B: It was able to discharge from all the nozzles 1 to less than 5 times of cleaning.
C: Some nozzles do not eject even after cleaning 5 times or more.
A and B are practical ranges.

(water resistant)
After solid printing with a printer equipped with a 720 dpi inkjet head, two test pieces dried at 100 ° C. for 3 minutes were immersed in ion-exchanged water and allowed to stand for 5 minutes. Evaluation was made according to the criteria. The density (OD value) of the printed material was measured by measuring the optical density (OD value) with a spectrophotometer (X-Rite 938 manufactured by X-Rite Inc.) The gloss of the printed material was visually evaluated.
A: No change in gloss is observed, or the density reduction is less than 10%.
B: Gloss change, discoloration, or density decrease of 10% or more and less than 30%.
C: The concentration is reduced by 30% or more.
A and B are practical ranges.

(Solvent resistance)
After solid printing with a printer equipped with a 720 dpi ink jet head, a test piece dried at 100 ° C. for 3 minutes was wiped with a 30% aqueous ethanol solution, and the change in gloss and density of the printed matter was visually evaluated according to the following criteria.
A: No change in gloss is observed, or the density reduction is less than 10%.
B: Gloss change, discoloration, or density decrease of 10% or more and less than 30%.
C: The concentration is reduced by 30% or more.
A and B are practical ranges.

(Applicability)
The state of the solid print portion was visually evaluated according to the following criteria with a printer equipped with a 720 dpi inkjet head.
A: There is no repelling or unevenness, and it can be applied uniformly.
B: Slight repelling and unevenness are observed.
C: Repelling and unevenness are remarkable.
A and B are practical ranges.

(Image clarity)
After printing with a printer equipped with a 720 dpi inkjet head, the state of bleeding at the boundary between the printed part and the non-printed part was visually evaluated according to the following criteria.
A: There is no blur and it is clear.
B: Slight bleeding is observed.
C: The bleeding is remarkable.
A and B are practical ranges.

(2) Ink set evaluation Inksets A to C (Examples 17 to 19) were obtained by combining the inks obtained in the above Examples and Comparative Examples. When printing was performed by the inkjet method using these ink sets, image evaluation and water resistance evaluation were performed in the case of no receiving solution and in the case of receiving solution. The evaluation criteria are shown below. The evaluation results are shown in Table 2 below.

In addition, coated paper (manufactured by Oji Paper Co., Ltd., mirror coat / platinum) was used as a recording medium in the case of no receiving solution. Also, ink of each color (black, blue, red, yellow) was printed by an inkjet method (manufactured by Konica Minolta, model number: KM512, droplet amount 10 pL, resolution 720 dpi) so as to form a pattern in which different colors are adjacent.

In addition, coated paper (manufactured by Oji Paper Co., Ltd., Mirror Coat Platinum) was used as a recording medium in the presence of a receiving solution. The receiving solution was attached to the printed surface of the coated paper by an inkjet method (manufactured by Konica Minolta, model number: KM512, droplet volume 10 pL, resolution 720 dpi). Next, a pattern in which different colors of ink of each color (black, blue, red, yellow) are adjacent to each other is formed on the receiving solution adhering portion by the inkjet method (droplet amount: 10 pL, resolution: 720 dpi) in the same manner as the receiving solution. Printed.
The receiving solution was obtained by mixing 5 parts by weight of calcium acetate, 5 parts by weight of calcium pantothenate, 30 parts by weight of propylene glycol, 0.5 parts by weight of Silface SAG503A, and 59.5 parts by weight of ion-exchanged water until uniform. .

(Image evaluation)
A color image was printed by a printer equipped with a 720 dpi inkjet head, and the image quality was evaluated.
A: There is no bleeding or color bleeding, and the image quality is good.
B: Slight bleeding or color bleeding is observed.
C: Bleeding and color bleeding are remarkable.
A and B are practical ranges.

(water resistant)
After printing with a printer equipped with a 720 dpi inkjet head, two dried test pieces were immersed in ion-exchanged water and allowed to stand for 5 minutes, and changes in gloss and density of the printed matter were evaluated according to the following criteria.
A: No change in gloss is observed, or the density reduction is less than 10%.
B: Gloss change, discoloration, or density decrease of 10% or more.
Note that A is a practical range.

(3) Summary From Table 1, when the acid value of the resin in the resin emulsion is 20 mgKOH / g or less, there is no generation of aggregates and no significant increase in the viscosity of the ink, and ejection properties and storage stability are good. Met.
Further, by including the compound represented by the formula (1), the dispersion stability of the resin was high, and the storage stability of the ink was good. Moreover, the discharge property was also good. Furthermore, it was excellent in penetrability, and it was possible to suppress the mixing of adjacent ink droplets before the ink droplets on the surface of the recording medium penetrated into the paper, and to achieve excellent image reproducibility with little blurring.
In addition, by including a polysiloxane compound, the surface tension of the ink can be lowered, the coating property is excellent, the surface of the coated paper is well adapted, can be sufficiently wetted and spread, and the solid portion is made uniform. I was able to form.
Thus, it was confirmed that the inks prepared in the examples were excellent in dispersion stability, and it was possible to produce printed matter excellent in water resistance, solvent resistance and image sharpness on the coated paper.

Further, the water-soluble organic solvent satisfying the ratio V50 / V20 of the viscosity of the 50% solution (V50) and the viscosity of the 20% aqueous solution (V20) within the range of 2.0 to 3.5 is 50% by mass in the solvent. In the following cases, since the ink fluidity at the time of ejection was low, the continuous ejection performance was lowered, or the fluidity after volatilization was low, and the intermittent ejection performance was lowered. Moreover, when it contained 50 mass% or more, both continuous discharge property and intermittent discharge property were favorable.

From Table 2, when the difference in surface tension between the inks is 1.0 mN / m or less, there is little bleeding between different colors (between inks), and the difference in surface tension between the inks is 1.0 mN / m. If it was larger, bleeding was significant. Furthermore, the image quality was improved by using the receiving solution together.
Thus, it was confirmed that an ink set having excellent image sharpness can be obtained by using the above ink.

Claims (9)

1. An ink composition for ink jet recording having a resin, a surfactant, a pigment, and a solvent;
   The resin has an acid value in the range of 0 mgKOH / g to 20 mgKOH / g, and is in an emulsion state in the ink composition for ink jet recording.
   The ink composition for ink jet recording, wherein the surfactant comprises a compound represented by the following general formula (1) and a polysiloxane compound.
   

   

   
   (In Formula (1), R ¹ and R ² are each hydrogen or a linear or branched alkyl group having 1 to 20 carbon atoms. M and n are each an integer of 0 to 20. M is monovalent. )
2. 2. The ink composition for ink jet recording according to claim 1, wherein the glass transition temperature of the resin is in the range of 5 ° C. to 90 ° C.
3. 3. The ink composition for ink jet recording according to claim 1, wherein the resin has a hydroxyl value in the range of 0 mgKOH / g to 20 mgKOH / g.
4. The ink composition for ink jet recording according to any one of claims 1 to 3, wherein the polysiloxane compound is a polyether group-modified polysiloxane compound.
5. The ink composition for inkjet recording according to any one of claims 1 to 4, wherein the polysiloxane compound is water-soluble.
6. 2 or more of the ink composition for inkjet recording according to any one of claims 1 to 5,
   The surface tension of the ink composition for inkjet recording is in the range of 20 mN / m to 30 mN / m,
   An ink set for ink jet recording, wherein a difference in surface tension between all the ink compositions for ink jet recording is 1 mN / m or less.
7. An ink composition for ink jet recording according to any one of claims 1 to 5,
   A receiving solution containing a polyvalent metal salt;
   An ink set for ink-jet recording, comprising:
8. An ink jet recording method, wherein printing is performed by an ink jet method using the ink composition for ink jet recording according to any one of claims 1 to 5.
9. An ink jet recording method, wherein printing is performed by an ink jet method using the ink set for ink jet recording according to claim 6 or 7.