JP2009102480A - Ink jet recording ink, ink set, and ink jet recording method - Google Patents

Abstract

Provided is an ink for ink jet recording that maintains low viscosity, has excellent fixability, and does not cause cockling and curling problems when printed on coated paper used for offset printing.
An ink for inkjet recording containing at least carbon black or an organic pigment (a), a solvent (b), and a resin (c), wherein the solvent (b) contains ethylene carbonate or propylene carbonate as a main component. The resin (c) uses an ink for ink jet recording characterized by containing, as a main component, a sulfonic acid group-containing organic polymer compound neutralized salt having a pH adjusted to 6.0 to 7.0.
[Selection figure] None

Description

  The present invention relates to an ink for ink jet recording having a solvent as a main component, low viscosity, and good fixability (setting property), an ink set using the ink, and an ink jet recording method using them.

  Ink jet recording inks are required to have a low viscosity in order to be ejected from a head as compared with general printing inks. In printers that use ink jet recording ink, there are printers that have a heater in the printer head and that reduce the viscosity by heating to enable ink jet discharge. However, having a heater in the printer head leads to an increase in power consumption, a complicated head structure, and an increase in size. Moreover, in order to improve the image quality, it is necessary to eject fine droplets. For this purpose, since the ink is ejected from a hole having a small diameter of the head orifice, the viscosity of the ink may be lower. Desired.

  The viscosity of ink for printing (offset printing, etc.) is generally several hundred mPa · s to several hundred Pa · s. In contrast, ink for ink jet recording is used as an ink jet printer for general consumers. The viscosity of the water-based ink for ink jet recording used is about 1.5 to 10 mPa · s, and the ink used for industrial use is about 10 to 30 mPa · s including oil-based (solvent) ink. is there. Therefore, compared to printing ink, the amount and type of pigment, resin, solvent and the like to be added are limited, and it is difficult to obtain good fixability.

  On the other hand, when water-based ink for ink-jet recording is used, a cockling phenomenon caused by swelling of fibers by water becomes a problem when printing on a paper medium. In order to suppress this, it is necessary to solve the problem by using an ink for ink jet recording using an organic solvent as a main solvent.

  Patent Document 1 shows an example in which a cyclic lactone such as γ-butyrolactone or ε-caprolactone is used as a solvent for ink jet recording in a mixed system with propylene glycol monoacetate monoalkyl ether. However, when the cyclic lactone and the cyclic carbonate are compared to each other, the boiling point of the cyclic carbonate is higher than that of the cyclic carbonate [γ-butyrolactone (molecular weight 86.09, boiling point 204 ° C.), ethylene carbonate (molecular weight 88.06, Boiling point: 243 ° C./740 mmHg), γ-valerolactone (molecular weight: 100.12, boiling point: 207 ° C.), propylene carbonate (molecular weight: 102.09, boiling point: 241 ° C.)], more desirable from the environment. On the other hand, when considering the penetration of the ink solvent into the paper medium, a low molecular weight compound is desirable.

  Patent Document 2 shows an example of an ink-jet aqueous dye ink composed of ethylene carbonate or propylene carbonate, polyethylene glycol, water, and a dye. However, it is only used as a dye, and only polyethylene glycol is used as the polymer compound. A polymer material that is not a neutralized salt such as polyethylene glycol is poor in fixability. In addition, in the neutralized salt obtained by neutralizing a general acrylic resin exemplified in Document 2, since the ethylene carbonate and propylene carbonate are hydrolyzed, the storage stability of the ink cannot be maintained. Further, in this document 2, there is a description in paragraph 0034 that triethanolamine, sodium hydroxide and the like can be used as a pH adjuster. However, the addition of such a base alone is ethylene carbonate. From the viewpoint of hydrolyzing propylene carbonate, practically, it must be said that practical use is difficult.

  In Patent Document 3, ethylene carbonate is used as a carrier in an ink to which a polymer comprising a monomer selected from styrene, acrylic acid, butyl acrylate, and the like and a polymerizable half ester comprising an aliphatic nonionic surfactant is added. Illustrated among the esters as aqueous organic solvents used in the media. However, mentioning the hydrolysis of ethylene carbonates, paragraph 0031 of this document 3 describes that it is desirable to adjust the pH to show alkalinity, and in the examples, it is used at pH 10 alkaline. It is merely illustrated as an example of esters.

  Patent Document 4 discloses an ink containing a pigment as a colorant and ethylene carbonate and glycol ethers as a solvent. The resin used is a general polyester resin. Similarly to the above, unless the polymer compound is a neutralized salt, the desired fixing property cannot be exhibited. Moreover, although this literature 4 also has illustrations, such as a triethanolamine and sodium hydroxide, as a pH adjuster, utilization of such a adjuster is realistic in using ethylene carbonate as a solvent like literature 2. It is difficult.

Patent Document 5 discloses an inkjet ink characterized by containing 20% or more of ethylene carbonate and 1,3-dimethyl-2-imidazolidinone and containing a pigment. Carboxylic acid type acrylic resin is used, and there is no problem of hydrolysis when 1,3-dimethyl-2-imidazolidinone is used as a solvent, but hydrolysis is caused when ethylene carbonate is used as a solvent. In the ink using the polymer dispersant obtained by copolymerizing styrene, methacrylic acid, octyl methacrylate, and hydroxyethyl methacrylate (10/40/20/30) in Examples of this document 5, Even if a solvent containing nate as a main component is used, the setability is poor. Further, when a neutralized salt obtained by neutralizing this copolymer with a base is used, hydrolysis of ethylene carbonate is caused.
JP 2005-200469 A Japanese Laid-Open Patent Publication No. 9-49038 JP 2002-60659 A JP 2004-43607 A JP 2006-45450 A

  The problem to be solved by the present invention is that the inkjet ink in which the carbon black or the organic pigment (a) is dispersed in the solvent (b) has excellent fixability while maintaining a low viscosity and is used for offset printing. An object of the present invention is to provide an ink for ink jet recording, an ink set, and an ink jet recording method which do not cause a problem of cockling or curling when printed on a craft paper.

Therefore, the present inventors have intensively studied in view of the actual situation,
An inkjet recording ink containing at least carbon black or an organic pigment (a), a solvent (b), and a resin (c), wherein the solvent (b) contains ethylene carbonate or propylene carbonate as a main component, and the resin ( c) completed the present invention by using an ink for ink jet recording characterized by containing a neutralized salt of a sulfonic acid group-containing organic polymer compound whose pH was adjusted to 6.0 to 7.0 as a main component. It came to do.

  That is, the present invention is an inkjet recording ink containing at least carbon black or an organic pigment (a), a solvent (b), and a resin (c), wherein the solvent (b) contains ethylene carbonate or propylene carbonate as a main component. And the resin (c) contains, as a main component, a sulfonic acid group-containing organic polymer compound neutralized salt having a pH adjusted to 6.0 to 7.0, and the ink for ink jet recording, An ink set for ink jet recording used, and an ink jet recording method using the same are provided.

  The ink for inkjet recording of the present invention is a sulfonic acid group-containing organic polymer in which the solvent (b) contains ethylene carbonate or propylene carbonate as a main component, and the resin (c) has a pH adjusted to 6.0 to 7.0. By containing a compound neutralized salt as a main component, there is no environmental problem with a low-viscosity ink, and there is a particularly remarkable effect in terms of fixability to a paper medium.

Details of the present invention will be described below.
The ink for ink jet recording of the present invention is an ink for ink jet recording containing at least carbon black or an organic pigment (a), a solvent (b), and a resin (c), wherein the solvent (b) is ethylene carbonate or propylene carbonate. As a main component, the resin (c) contains a neutralized salt of a sulfonic acid group-containing organic polymer compound having a pH adjusted to 6.0 to 7.0 as a main component.

<Solvent (b)>
This ink for ink jet recording has a lower molecular weight and a higher boiling point than cyclic lactones and glycols in that it is mainly composed of cyclic carbonate, ethylene carbonate or propylene carbonate, as a high boiling point solvent. A system can be made. As described above, the solvent used in the ink is desired to have a high boiling point in terms of the environment. However, considering the fixability, a low molecular weight compound having excellent permeability is desirable. On the other hand, by reducing the amount of water and using a high-boiling solvent as a main component, it is possible to increase the affinity for a more hydrophobic recording medium as compared with an ink containing water as a main component. The paper medium includes various recording media from paper made suitable for an ink containing oil as a main component, such as offset ink, to a medium dedicated to water-based ink for inkjet recording. When water-based ink is printed on paper used for offset printing, the ink is repelled and unevenness occurs. On the other hand, when the solvent has a high molecular weight and a high boiling point, the penetration into the paper becomes slow, resulting in poor fixability.

(recoding media)
The recording medium used in the present invention is PPC paper, plain paper such as high-quality paper, ink jet dedicated paper (matte paper, glossy paper, etc.), coated paper used for general printing (matte, dull, glossy) Etc. can be used suitably. Inkjet glossy paper includes cast coat type, swelling type, and microporous type, and any type can be used. For coated paper, depending on the coating amount of surface resin, art paper (coating amount of about 40 g / m ² ), coated paper (coating amount of about 20 g / m ² ), lightweight coated paper (coating amount of 15 g) / M ² ) and finely coated paper (coating amount 12 g / m ² or less). The greater the coating amount, the better the gloss, but the poor water absorption. Furthermore, the water-based ink is likely to be repelled by the resin. Coated paper and lightweight coated paper are highly demanded for general printing and are less expensive than glossy paper dedicated to inkjet. Therefore, there is a high need for printing with inkjet, and ink that can be printed on such coated paper. Is desired.

  The ink for inkjet recording of the present invention can contain water as a mixed solvent. The amount of water added can be 20 wt% to 40 wt% with respect to the total weight of the ink. When water is further contained, there is a possibility that the cockling phenomenon due to the deformation of the paper due to the expansion due to the swelling of the paper fibers may remarkably occur. Inkjet special paper is a recording medium that has a receiving layer with a sufficient liquid absorption amount that can absorb the aqueous solvent of the inkjet ink, and it is difficult for the cockling problem to occur. When printing on a medium, it is necessary to control the amount of water added. In the case of such a low liquid-absorbing paper medium, an ink-jet ink mainly containing a high-boiling solvent that suppresses cockling can be obtained by containing 20 to 30% by weight of water with respect to the total weight of the ink. Therefore, it is more preferable. When the amount of water is less than this, the viscosity of the ink becomes high and the fixability is poor.

  As the high boiling point solvent in the present invention, a cyclic carbonate compound having a boiling point of 240 ° C. or higher, a flash point of 70 ° C. or higher, and a viscosity at 20 ° C. of 10 mPa · s or lower can be used. Ethylene carbonate and propylene carbonate are preferred compounds. In particular, ethylene carbonate is a preferred solvent from the viewpoint of molecular weight and boiling point. The mixed solvent (b) containing ethylene carbonate or propylene carbonate as a main component is a mixed solvent containing 20 wt% to 40 wt% of water, and the viscosity of the mixed solvent at 20 ° C. is 10 mPa · s or less. More preferably.

  In the mixed solvent (b), it is preferable to add a cyclic compound having a higher flash point to the cyclic carbonate compound as a high-boiling solvent because it increases safety. As such a compound, sulfolane, which is a kind of cyclic sulfone, can be used. Addition of sulfolane can be expected to improve curling properties. The amount of sulfolane added may be 1% to 30% with respect to the total weight of the ink. However, if the amount added is too large, the permeability of the solvent into the paper is lowered and the fixability is inferior.

  Containing 5 to 30% by weight of glycols (glycol ethers) with respect to the total amount of ink for the purpose of controlling ink penetration, controlling gloss and paper curling, and controlling head drying. Can do. Examples of glycols include triethylene glycol monomethyl ether, tripropylene glycol monomethyl ether, triethylene glycol monobutyl ether, tetraethylene glycol dimethyl ether, and tripropylene glycol monomethyl ether. Ethylene oxide adducts or propylene oxide adducts of sugars such as polyethylene oxide pentaerythritol ether, glycerin, pyrrolidones, sulfolane, 1,3-dimethyl-2-imidazolidinone can also be used in the same manner as the glycols. . These solvents can also be used as single or multiple mixtures.

<Carbon black or organic pigment (a)>
The colorant in the present invention is not particularly limited, and any known and commonly used carbon black or organic pigment can be used. Examples of organic pigments include azo pigments, indanthrene pigments, phthalocyanine pigments, quinacridone pigments, perylene pigments, isoindolinone pigments, quinophthalone pigments, anthraquinone pigments, diketopyrrolopyrrole pigments, and the like. It is done.

  In the present invention, the organic pigment is any of a method of dispersing with a pigment dispersant, a method of using a treated pigment having a polar functional group introduced into the surface of the particle by a chemical reaction, or a method of using in the form of microcapsule type composite particles It is also possible to use the method. Carbon black can be used by a method of dispersing with a pigment dispersant.

  The pigment dispersant is not particularly limited, and a known pigment dispersant can be used. For example, various types such as nonionic type, block copolymer type, and polyester type can be used. In selecting a pigment dispersant at that time, it is important to select a material that is soluble in the solvent to be used in order to obtain dispersibility. In any case, it is necessary that the material does not hydrolyze ethylene carbonate or propylene carbonate. The combined use of a pigment derivative (synergist) together with a pigment dispersant is effective for improving the rheology of the ink. As the synergist, a derivative having a sulfonic acid functional group such as a sulfonic acid metal salt or a sulfonic acid amide in the organic pigment skeleton is preferable because it has an excellent rheological improvement effect.

  The pigment dispersant can be added in an amount of 1% by weight or more and 200% by weight with respect to the pigment. Further, in the case of a nonionic pigment dispersing agent that does not take the form of a neutralized salt, the fixing property is inferior when the amount added is increased with respect to the neutralized salt of the sulfonic acid group-containing organic polymer compound. The nonionic pigment dispersant is desirably less than 30% with respect to the sulfonic acid group-containing organic polymer compound.

  The addition amount of the pigment derivative is preferably 5% by weight or more and less than 20% by weight with respect to the organic pigment. When the amount of the derivative added is small, the rheology improving effect is reduced. On the other hand, if the amount added is too large, it is not preferable in terms of hue change and saturation reduction of the ink.

  A treated pigment (self-dispersing pigment) in which a polar functional group is introduced into the surface of an organic pigment by a chemical reaction is not limited by the treatment amount of the functional group and the production method, but the azo coupling method, Diels-Alder It is created by the process, oxidation method, etc. Since these self-dispersing pigments have a covalent bond and an ionic functional group on the surface, a dispersion force can be obtained by electrostatic repulsion. In addition, since it is bonded by a covalent bond, a component having a dispersion force is not removed by various solvents, which is effective in terms of solvent resistance. Since the prepared treated pigment is provided in the form of powder, it must be dispersed in an appropriate solvent. In this case, it is effective to use a pigment dispersant in combination.

  The microcapsule type composite particles are desirable because they can achieve good dispersibility, dispersion stabilization, and low ink viscosity. The microcapsule type composite particle is composed of an organic pigment serving as a nucleus and a polymer compound covering the organic pigment. The polymer compound is preferably a resin whose aqueous resin solution is in the range of pH 6.0 to 7.0 so as not to hydrolyze ethylene carbonate and propylene carbonate. In particular, a resin containing a sulfonic acid group converted to an alkali metal salt is desirable.

<Resin (c)>
In the ink for inkjet recording, the resin is added as a part or all of the above-described pigment dispersant. In the present invention, the resin (c) contains a sulfonic acid group-containing organic polymer compound neutralized salt as a main component.

  As the resin added to the ink for inkjet recording, styrene- (meth) acrylic acid resin, styrene-maleic acid resin, rosin phenol resin, vinyl acetate resin, polyurethane resin, polyester resin, epoxy resin, silicone resin, etc. can be used. However, in order not to hydrolyze ethylene carbonate and propylene carbonate, it is desirable that the pH is 6.0 to 7.0 in the resin aqueous solution. It is possible to adjust the pH by neutralizing a resin containing a carboxylic acid group, such as styrene- (meth) acrylic acid resin, with a low neutralization rate, but strong acid such as sulfonic acid, sodium hydroxide, hydroxylation Neutralized salts with strong bases such as potassium and lithium hydroxide are desirable because they can maintain pH 6.0 to 7.0 and achieve pigment dispersion stability even when neutralized to a high neutralization rate. For this reason, in this invention, a sulfonic acid group containing high molecular compound neutralized salt shall be included as a main component. Thereby, hydrolysis of ethylene carbonate and propylene carbonate can be avoided, and excellent fixability to paper can be achieved for the ink for ink jet recording. In particular, a lithium salt of a sulfonic acid group-containing polymer compound is more preferable because it has excellent solubility in a solvent composition containing 20% to 40% of water in ethylene carbonate and propylene carbonate.

  The sulfonic acid group-containing polymer compound neutralized salt can be added in an amount of 3 to 20% by weight based on the total amount of the ink. If the amount added is too large, the viscosity becomes high and ink jet discharge becomes difficult. On the other hand, if the amount added is small, the fixability becomes insufficient. When a cyclic carbonate such as ethylene carbonate or propylene carbonate is used as the solvent (b) as a main solvent, and glycols (glycerin, diethylene glycol, diethylene glycol monoalkyl ether, triethylene glycol monoalkyl ether used for water-based ink for inkjet recording) In comparison with the case of using dipropylene glycol monoalkyl ether, etc.), when using cyclic carbonate, even if the resin addition amount is increased, the increase in viscosity is low and the resin addition amount may be increased. This is advantageous in terms of fixability.

  In the case where the sulfonic acid group-containing polymer is a copolymer composed of a copolymerizable ethylenically unsaturated monomer (described in detail later), the acid value of the copolymer is preferably from 30 to 130. More preferably, the acid value is 50 to 110 mgKOH / g. When the acid value is too high, the viscosity becomes too high when used as a solvent (oil-based) ink. Moreover, when an acid value is too low, the solubility of resin (c) to the solvent (b) composition which has ethylene carbonate or propylene carbonate as a main component and contains 20-40% of water becomes low, and it is difficult to use it. Here, the acid value means the number of mg of potassium hydroxide required to neutralize 1 g of the resin content.

  Examples of the sulfonic acid group-containing polymer compound include homopolymers or copolymers containing a sulfonic acid group-containing ethylenically unsaturated compound as a monomer. When the sulfonic acid group-containing polymer compound is a copolymer containing a monomer other than the sulfonic acid group-containing ethylenically unsaturated compound, as the monomer used in combination, as described later, an ethylenically unsaturated monomer, Monoethylenically unsaturated monomers containing carboxyl groups, monoethylenically unsaturated monomers containing amide groups, monoethylenically unsaturated monomers containing polyoxyalkylene groups, crosslinkable ethylenic monomers Examples thereof include unsaturated monomers.

  Examples of the sulfonic acid group-containing ethylenically unsaturated monomer include a (meth) acrylamide-alkanesulfonic acid such as 2-acrylamido-2-methylpropanesulfonic acid, and a sulfoalkyl (meta) such as 2-sulfoethyl acrylate. ) Acrylate, terminal sulfonic acid modified polyethylene glycol mono (meth) acrylate, vinyl sulfonic acid, allyl sulfonic acid, methallyl sulfonic acid, alkenyl sulfonic acid, styrene sulfonic acid, α-methyl styrene sulfonic acid, allyloxybenzene sulfonic acid, meta Examples include ryloxybenzenesulfonic acid and alkylallylsulfosuccinic acid. (Meth) acrylamide-alkanesulfonic acid such as 2-acrylamido-2-methylpropanesulfonic acid, sulfoalkyl (meth) acrylate such as 2-sulfoethyl acrylate, terminal sulfonic acid-modified polyethylene glycol mono (meth) acrylate Monomers derived from (meth) acrylic acid having such an unsaturated bond are preferable because they are excellent in polymerizability and can be easily incorporated into the copolymer.

  An ethylenically unsaturated monomer copolymerizable with the sulfonic acid group-containing ethylenically unsaturated monomer can be used. Examples of the copolymerizable ethylenically unsaturated monomer include vinyl compounds such as vinyl acetate and vinyl chloride; heterocyclic vinyl compounds such as vinyl pyrrolidone; styrene, α-methylstyrene, dimethylstyrene, tert- Aromatic vinyl compounds such as butylstyrene and chlorostyrene; benzyl (meth) acrylate, phenyl (meth) acrylate, phenylethyl (meth) acrylate, phenylpropyl (meth) acrylate, phenoxyethyl (meth) acrylate, methyl (meth) Acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, iso-propyl (meth) acrylate, n-butyl (meth) acrylate, iso-butyl (meth) acrylate, tert-butyl (meth) acrylate, 2- D Ruhexyl (meth) acrylate, n-octyl (meth) acrylate, dodecyl (meth) acrylate, octadecyl (meth) acrylate, cyclohexyl (meth) acrylate, isobornyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxy Examples include (meth) acrylic acid esters such as propyl (meth) acrylate.

  If necessary, a monoethylenically unsaturated monomer containing a carboxyl group can be used in combination. Examples of such monomers include acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, mono n-butyl maleate, mono n-butyl fumarate, mono n-butyl itaconic acid, crotonic acid, ω-carboxy-polycaprolactone monoacrylate and the like.

  A monoethylenically unsaturated monomer containing an amide group can also be used in combination. Examples of such a monomer include acrylamide, methacrylamide, N-methyl (meth) acrylamide, N-ethyl (meth) acrylamide, and N-isopropyl (meth) other than the above (meth) acrylamide-alkanesulfonic acid. Acrylamide, N, N-dimethyl (meth) acrylamide, N, N-diethyl (meth) acrylamide, (meth) acryloylmorpholine, N, N-dimethylaminopropylacrylamide, N-methylolacrylamide, Nn-butoxymethylacrylamide, N-isobutoxymethyl acrylamide, diacetone acrylamide, maleic acid amide, etc. are mentioned. Acrylamide, methacrylamide, N-methyl (meth) acrylamide, N-ethyl (meth) acrylamide, N-isopropyl (meth) acrylamide, N, N-dimethyl (meth) acrylamide, N, N-diethyl (meth) acrylamide are The copolymer containing these monomers increases the solubility in cyclic carbonates (ethylene carbonate or propylene carbonate, mixed solvent of ethylene carbonate and propylene carbonate) in a mixed solvent containing 20 wt% to 40 wt% of water. Is more preferable.

  A monoethylenically unsaturated monomer containing a polyoxyalkylene group can also be used in combination. Examples of such monomers include polyethylene glycol mono (meth) acrylate, polypropylene glycol mono (meth) acrylate, poly (ethylene glycol-propylene glycol) mono (meth) acrylate, and polyethylene glycol-polypropylene glycol mono (meth). Polyalkylene glycol mono, such as acrylate, poly (ethylene glycol-polytetramethylene glycol) mono (meth) acrylate, poly (propylene glycol-tetramethylene glycol) mono (meth) acrylate, propylene glycol-polybutylene glycol mono (meth) acrylate, etc. (Meth) acrylate;

Methoxypolyethylene glycol mono (meth) acrylate, ethoxydiethylene glycol mono (meth) acrylate, lauroxy polyethylene glycol mono (meth) acrylate, stearoxy polyethylene glycol mono (meth) acrylate, methoxypoly (ethylene glycol-propylene glycol) mono (meth) acrylate Alkoxypolyalkylene glycol mono (meth) acrylates such as octoxypolyethylene glycol-polypropylene glycol monomethacrylate; phenoxypolyethylene glycol mono (meth) acrylate, nonylphenoxypolyethylene glycol mono (meth) acrylate, nonylphenoxypoly (ethylene glycol-propylene glycol) ) Poly, such as mono (meth) acrylate Monoethylenically unsaturated monomers containing an oxyalkylene group. The copolymer containing these monomers increases the solubility in a mixed solvent containing 20 wt% to 40 wt% of water in cyclic carbonates (ethylene carbonate or propylene carbonate, a mixed solvent of ethylene carbonate and propylene carbonate), And since the fixability of the inkjet ink using the copolymer containing these monomers is excellent, it is more preferable. Methoxypolyethylene glycol mono (meth) acrylate and ethoxydiethylene glycol mono (meth) acrylate are more preferable because they can be introduced into the copolymer without increasing the viscosity more than necessary.

  Even if the above copolymer is a linear copolymer consisting only of polymerized units of monoethylenically unsaturated monomer, a very small amount of copolymerized ethylenically unsaturated monomer is copolymerized. And a copolymer containing a partially crosslinked part.

  Examples of such ethylenically unsaturated monomers having crosslinkability include glycidyl (meth) acrylate, diallyl phthalate, divinylbenzene, allyl (meth) acrylate, ethylene glycol di (meth) acrylate, and triethylene glycol diester. (Meth) acrylate, 1,9-nonanediol di (meth) acrylate, glycerin dimethacrylate, 2-hydroxy-3-acryloyloxypropyl methacrylate, polyethylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, polytetra Methylene glycol di (meth) acrylate, poly (ethylene glycol-tetramethylene glycol) di (meth) acrylate, poly (propylene glycol-tetramethylene glycol) di (meth) Acrylate, polyethylene glycol-polypropylene glycol-polyethylene glycol di (meth) acrylate, ethylene oxide modified bisphenol A di (meth) acrylate, allyloxy polyethylene glycol-polypropylene glycol mono (meth) acrylate, trimethylolpropane tri (meth) acrylate, tri Examples thereof include monomers containing two or more unsaturated bonds in one molecule, such as tri (meth) acrylate of an alkylene oxide adduct of methylolpropane and tri (meth) acrylate of an alkylene oxide adduct of glycerin.

  The molecular weight of the copolymer is not particularly limited. For example, from the viewpoint of film formation, the weight average molecular weight is 5,000 to 100,000. Among them, 5,000 to 40,000 in terms of low viscosity and easy handling. 000 is preferred.

  In the present invention, in the sulfonic acid group-containing organic polymer compound, the reaction rate of each monomer used is considered to be substantially the same, and the charge ratio of each monomer is calculated in terms of mass of the polymerization unit of each monomer. It shall be regarded as a content ratio. The copolymer in the present invention can be synthesized by various conventionally known reaction methods such as bulk polymerization, solution polymerization, suspension polymerization, and emulsion polymerization. In this case, known and commonly used polymerization initiators, surfactants and antifoaming agents can be used in combination.

  In the present invention, a chain transfer agent may be used to adjust the molecular weight of the sulfonic acid group-containing organic polymer compound. Among them, typical examples include lauryl mercaptan, tert-dodecyl mercaptan, β-mercaptopropionic acid, 1-thioglycerol, and the like, and one or more of these may be used in combination. I can do it.

  When the sulfonic acid group-containing organic polymer compound is a substantially linear copolymer, it is suitable for the preparation of a water-based ink for an inkjet recording apparatus with a piezo-type nozzle that does not have a thermal history, When it is a copolymer containing a partially crosslinked part, it is suitable for the preparation of a water-based ink for an ink jet recording apparatus of a thermal type nozzle having a thermal history.

  The ratio of the neutralized acid group in the sulfonic acid group-containing organic polymer compound is usually set in the range of 30 to 100%, particularly 70 to 100%. This ratio of ionized groups does not mean the molar ratio of sulfonic acid groups to basic substances, but takes into account dissociation equilibrium.

  As the basic substance for neutralizing the sulfonic acid group-containing organic polymer compound, any known and commonly used substances can be used. For example, inorganic basic substances such as sodium hydroxide, potassium hydroxide, lithium hydroxide, and ammonia. Alternatively, organic basic substances such as triethylamine and alkanolamine can be used. Strong bases such as sodium hydroxide, potassium hydroxide and lithium hydroxide are suitable for maintaining the pH of the sulfonic acid group-containing organic polymer compound neutralized salt at 6.0 to 7.0. Lithium hydroxide is composed of a sulfonic acid group-containing organic polymer compound and a neutralized salt of lithium hydroxide, cyclic carbonates (ethylene carbonate or propylene carbonate, mixed solvent of ethylene carbonate and propylene carbonate) and water in an amount of 20% by weight to 40%. It is more preferable because it has excellent solubility in a mixed solvent containing 5% by weight.

  The basic substance for neutralizing the sulfonic acid group-containing organic polymer compound may be partially or completely used during polymerization of the sulfonic acid group-containing organic polymer compound, or partially neutralized or unneutralized. A part or all of the sulfonic acid group-containing organic polymer compound may be used.

  The pH of the neutralized salt of the sulfonic acid group-containing organic polymer compound is preferably in the range of 6.0 to 7.0, and more preferably in the range of 6.3 to 7.0. Furthermore, it is more preferable that it is in the range of 6.5 to 7.0. If it is this range, a hydrolysis of a cyclic carbonate can be suppressed at the time of mixing with the following cyclic carbonate.

  In this invention, after neutralizing a sulfonic acid group containing organic polymer compound with a basic substance, it is preferable to include the process of mixing a cyclic carbonate as essential. The mixture comprising a sulfonic acid group-containing organic polymer compound, a basic substance and a cyclic carbonate may contain water or a mixture of water and a water-soluble organic solvent.

  Examples of the water-soluble organic solvent include ketones such as acetone, methyl ethyl ketone (MEK), methyl butyl ketone, and methyl isobutyl ketone; methanol, ethanol, 2-propanol (IPA), 2-methyl-1-propanol, 1- Examples include alcohols such as butanol and 2-methoxyethanol; ethers such as tetrahydrofuran, 1,4-dioxane and 1,2-dimethoxyethane; amides such as dimethylformamide and N-methylpyrrolidone, and particularly carbon. It is preferable to use a compound selected from the group consisting of a ketone having 3 to 6 atoms and an alcohol having 1 to 5 carbon atoms. These water-soluble organic solvents and water may be used as a polymerization solvent for the sulfonic acid group-containing organic polymer compound, or may be contained when the sulfonic acid group-containing organic polymer compound and the basic substance are mixed, You may make it contain at the time of mixing the mixture of a sulfonic acid group containing organic polymer compound and a basic substance, and cyclic carbonate.

  In the present invention, the water-soluble organic solvent is desirably removed by distillation after the step of mixing the cyclic carbonate after neutralizing the sulfonic acid group-containing organic polymer compound with a basic substance. If these water-soluble organic solvents do not adversely affect the properties of the final inkjet ink, they may remain as they are.

  Polyurethane resins as sulfonic acid group-containing polymer compounds can also be used. Such a sulfonic acid group-containing polyurethane resin contains two or more urethane bonds as essential components in one molecule. This polyurethane resin includes not only a urethane bond but also a polyurethane polyurea resin containing a urea bond.

  When the sulfonic acid group-containing polymer compound is a sulfonic acid group-containing polyurethane resin, the acid value is desirably 20 to 60 mgKOH / g. When the acid value is too high, the viscosity becomes too high, and the resin synthesis is difficult. On the other hand, if the acid value is too low, the fixability is inferior.

  Such a polyurethane resin can be obtained, for example, by reacting organic diisocyanate and diol as essential components. Examples of the diol include a low-molecular diol having a molecular weight of less than 800 and a high-molecular diol having a molecular weight of 800 or more, such as polyether diol, polyester diol, polyester ether diol, and polycarbonate diol. Among them, in the present invention, as a raw material component for forming a linear aromatic unit comprising an aromatic ring in the main chain constituting a polyurethane resin, polyester diol, polyester ether diol, polycarbonate having good adhesion and durability It is preferable to use a diol.

The raw material for introducing the sulfonic acid group _(-SO 3 H) in the polyurethane resin, for example, 2-sulfo-1,3-propanediol, _-SO 3 H and 2-sulfo-1,4-butanediol Examples thereof include various low-molecular diols, sulfonic acid group-containing low-molecular diols and various salts of ammonia, organic amines, alkali metals, and alkaline earth metals, and mixtures of two or more of these. In order to suppress hydrolysis of ethylene carbonate and propylene carbonate, low molecular weight diols containing sulfonic acid groups such as 2-sulfo-1,3-propanediol and 2-sulfo-1,4-butanediol are alkali metals. Neutralized neutralized salts are more preferred as sulfonic acid group-containing polymer compound neutralized salts.

  Examples of compounds that can be used as chain extenders in the production of polyurethane resins include inorganic compounds having active hydrogen atoms such as ammonia, ethylenediamine, hexamethylenediamine, isophoronediamine, diaminodiphenylmethane, diaminodiphenylsulfone, and diaminodicyclohexylmethane. Diamines such as tolylenediamine (compounds having two amino groups in the molecule such as aliphatic diamine, alicyclic diamine, aromatic diamine) and dialkanolamines such as diethanolamine and dipropanolamine . In addition to the addition of diamines as chain extenders, remaining in the system causes decomposition of ethylene carbonate and propylene carbonate.

  In producing the polymer diol or polyurethane resin, a nonionic hydrophilic atomic group such as polyoxyethylene is used as long as it does not impair the technical effect in the case of having only a sulfonic acid group. May be included in the structure. Moreover, as long as the technical effect in the case of being substantially linear is not impaired, in addition to the above-mentioned various raw materials, if necessary, an organic compound having one active hydrogen atom or three or more active hydrogen atoms An organic compound may be used in combination.

  Ink for inkjet recording can also be obtained by directly blending and dispersing the final ink composition, but from the viewpoint of production efficiency such as viscosity adjustment and dispersion efficiency, the above-mentioned pigment and sulfonic acid group-containing polymer compound A pigment dispersion with a high concentration dispersed in a system containing a cyclic carbonate solvent and water, using a combination of a salt, a pigment and a sulfonic acid group-containing polymer compound neutralized salt and a dispersant, and a pigment and a dispersant. Later, a neutralized salt of a sulfonic acid group-containing polymer compound is further added as a binder resin to the pigment dispersion, and a cyclic carbonate (ethylene carbonate or propylene carbonate, a mixture of ethylene carbonate and propylene carbonate) solvent, water, Addition of glycols, other auxiliary solvents, surfactants, etc. as moisturizers to prevent drying if necessary It was added and the pigment concentration, solvent concentration, water content, and, by adjusting the viscosity, a method of obtaining an inkjet recording ink is efficient.

  As additives such as surfactants, nonionic, silicone, and fluorine surfactants can be used alone or in combination of several kinds. The addition amount of the nonionic or silicone based additive such as a surfactant is about 1% by weight to 5% by weight, preferably 1% by weight to 3% by weight, based on the total amount of the ink. The addition amount of the fluorine-based surfactant or the like is preferably about 0.001% by weight to 0.1% by weight with respect to the total amount of the ink. Fluorine-based surfactants and the like can improve fluidity, foamability, and the like when used in combination with nonionic or silicone-based surfactants.

  Thus, the ink for ink jet recording of the present invention finally adjusted to a pigment content of 0.5 to 10% in terms of mass can be obtained. In addition, the obtained ink for ink jet recording can be subjected to centrifugal separation or filtration with a microfilter, if necessary, to remove coarse particles and undersized particles, and to adjust the particle size distribution of dispersed particles. Etc. can be extremely reduced.

  The higher the pigment content in the ink for ink jet recording, it is desirable because the color density can be increased while reducing the solvent component penetrating into the paper. A pigment content of 0.5 to 10% is desirable. In normal applications, 3 to 8% can be exemplified as the pigment content, but in light ink applications, the pigment content may be lower. Furthermore, considering the balance between the increase in color density due to the addition of pigment and the increase in viscosity, it is more preferably 4 to 7%. If the ink jet head is improved and a higher viscosity ink can be discharged, this is not the case.

The ink jet recording ink has a viscosity at 20 ° C. of 30 mPa · s or less, and particularly an ink for ink jet recording of 3 to 20 mPa · s can be ejected by selecting a commercially available head. In order to obtain a higher-definition image, the ejected droplets become smaller. In such a case, a lower viscosity ink for inkjet recording is required. Therefore, the viscosity at 20 ° C. of the ink for inkjet recording is more preferably 3 to 13 mPa · s. Furthermore, it is desirable that it is 3-10 mPa * s.
This ink for ink jet recording naturally includes a resin for obtaining fixability, a resin for obtaining dispersion stability, a dispersant, and the like, and can obtain desired stability as an ink for ink jet recording. As an ink for inkjet recording, it is necessary to satisfy the above viscosity range. Such a viscosity range is not limited to this as long as the ink jet head is improved and a higher viscosity ink can be ejected.

  The ink for inkjet recording of the present invention is not particularly limited in terms of the number of ink colors, and red (R), blue (B), green (G), yellow (Y), magenta (M), cyan (C) and at least one color ink selected from the group consisting of black (K). One color ink or two or more color ink sets may be used. In addition, the use of a light ink having a low pigment content in the ink is a preferable method for increasing density gradation.

  In the present invention, by performing ink jet recording on a recording medium, a recorded matter in which a colored image is formed on the recording medium can be obtained.

  The ink for ink-jet recording and the ink set for ink-jet recording of the present invention can be used in a method for ink-jet recording onto a known and commonly used recording medium. As a recording medium at this time, for example, plain paper such as PPC paper and high-quality paper, photographic paper (glossy), special paper for inkjet recording such as photographic paper (silk-tone), etc. (matte paper, glossy paper, etc.) , Coated paper (matt, dull, gloss) used for offset printing, and other synthetic resin films such as OHP films. In particular, the ink for ink jet recording and the ink set for ink jet recording of the present invention are effective in improving the color developability of paper for exclusive use for ink jet recording and coated paper used for offset printing.

  Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples. In the following examples and comparative examples, “part” and “%” are both based on mass.

<Synthesis Example 1> (Resin 1; carboxylic acid group-containing resin neutralized salt)
MEK is added to a reaction vessel of an automatic polymerization reaction device (polymerization tester DSL-2AS type, manufactured by Sakai Sangyo Co., Ltd.) having a reaction vessel equipped with a stirring device, a dropping device, a temperature sensor, and a reflux device having a nitrogen introduction device at the top. (2-butanone) 1100 parts were charged, and the inside of the reaction vessel was purged with nitrogen while stirring. After raising the temperature in the reaction vessel to 80 ° C. while maintaining a nitrogen atmosphere, 75 parts 2-hydroxyethyl methacrylate, 200 parts styrene, 199 parts methacrylic acid, 503 parts butyl methacrylate, 23 parts butyl acrylate from a dropping device. A mixture of 80 parts of a polymerization initiator “Perbutyl (registered trademark) O” (manufactured by NOF Corporation) was dropped over 4 hours. After completion of the dropping, the reaction was further continued at the same temperature for 7 hours to obtain a MEK solution of a copolymer (resin 1) having an acid value of 130 and a nonvolatile content of 48%.

  To 41.67 parts of resin 1, 6.57 parts of triethanolamine and 51.77 parts of ion-exchanged water were added and stirred to dissolve the resin. The resin aqueous solution is heated to 100 ° C. to 130 ° C. by a distillation apparatus to distill most of MEK and water. Before the resin cools, 50 parts of ethylene carbonate and 20 parts of water are added and stirred to prepare an ethylene carbonate solution. A part of the resin solution was taken out, the nonvolatile content was measured, and a necessary amount of ion-exchanged water was added to obtain an alkali neutralized ethylene carbonate solution of resin 1 (resin content 20.97%, moisture 30%). (Resin solution A-1)

<Synthesis example 2> (resin 2; sulfonic acid group-containing resin (sodium neutralized salt))
Ethanol in a reaction vessel of an automatic polymerization reaction device (polymerization tester DSL-2AS type, manufactured by Sakai Sangyo Co., Ltd.) having a reaction vessel equipped with a stirring device, a dropping device, a temperature sensor, and a reflux device having a nitrogen introduction device at the top 1200 parts were charged, and the inside of the reaction vessel was purged with nitrogen while stirring. After raising the temperature inside the reaction vessel to 80 ° C. while maintaining a nitrogen atmosphere, 200 parts of styrene, 269.3 parts of butyl acrylate, 200 parts of benzyl methacrylate, and a polymerization initiator “Perbutyl (registered trademark) O” were added from a dropping device. (Manufactured by Nippon Oil & Fats Co., Ltd.) From a mixed solution of 80 parts and another dropping device, a solution prepared by dissolving 220.5 parts of sodium 4-vinylbenzenesulfonate in 700 parts of water was dropped simultaneously over 4 hours. . After completion of the dropwise addition, the reaction was further continued for 7 hours at the same temperature. After the reaction, a white precipitate was formed. The solid was removed by decantation, and the solvent was completely removed with a dryer at 140 ° C. to give a copolymer having an acid value of 60 (resin 2 ) Was obtained.

  50 parts of ethylene carbonate and 30 parts of ion-exchanged water are added to 20 parts of resin 2 solid matter, and the mixture is heated and stirred to completely dissolve, and an ethylene carbonate solution of resin 2 having a resin content of 20% and a water content of 30% ( Resin solution A-2) was obtained.

<Synthesis Example 3> (Resin 3; carboxylic acid group-containing resin)
MEK is added to a reaction vessel of an automatic polymerization reaction device (polymerization tester DSL-2AS type, manufactured by Sakai Sangyo Co., Ltd.) having a reaction vessel equipped with a stirring device, a dropping device, a temperature sensor, and a reflux device having a nitrogen introduction device at the top. (2-butanone) 1100 parts were charged, and the inside of the reaction vessel was purged with nitrogen while stirring. After raising the temperature in the reaction vessel to 80 ° C. while maintaining a nitrogen atmosphere, 150 parts of 2-hydroxyethyl methacrylate, 200 parts of styrene, 92 parts of methacrylic acid, 370 parts of butyl methacrylate, glycidyl methacrylate, 30. 0 part, 40.0 parts of a polymerization degree adjusting agent “Blemmer TGL” (manufactured by NOF Corporation) and 100.0 parts of a polymerization initiator “Perbutyl (registered trademark) O” (manufactured by NOF Corporation) Was added dropwise over 4 hours. After completion of the dropwise addition, the reaction was further continued at the same temperature for 7 hours to obtain a MEK solution (resin solution A-3) of a copolymer (resin 3) having an acid value of 60 and a nonvolatile content of 53.18%.

<Synthesis Example 4> (resin 4; sulfonic acid group-containing resin (sodium neutralized salt))
Ethanol in a reaction vessel of an automatic polymerization reaction device (polymerization tester DSL-2AS type, manufactured by Sakai Sangyo Co., Ltd.) having a reaction vessel equipped with a stirring device, a dropping device, a temperature sensor, and a reflux device having a nitrogen introduction device at the top 1600 parts, a solution of 330.7 parts of sodium 4-vinylbenzenesulfonate in 992.1 parts of water was charged, and the inside of the reaction vessel was purged with nitrogen while stirring. After raising the temperature inside the reaction vessel to 80 ° C. while maintaining a nitrogen atmosphere, 200 parts of styrene, 269.3 parts of butyl acrylate, 200 parts of benzyl methacrylate, and a polymerization initiator “Perbutyl (registered trademark) O” were added from a dropping device. (Nippon Yushi Co., Ltd.) 80 parts of the mixed solution was added dropwise over 4 hours. After completion of the dropping, the reaction was further continued at the same temperature for 7 hours to obtain a suspension solution (resin solution A-4) of a copolymer (resin 4) having an acid value of 90 and a nonvolatile content of 27.1%.

<Synthesis Example 5> (Resin 5; sulfonic acid group-containing resin neutralized salt)
The reaction vessel of the automatic polymerization reaction device (polymerization tester DSL-2AS type, manufactured by Sakai Sangyo Co., Ltd.) having a reaction vessel equipped with a stirring device, a dropping device, a temperature sensor, and a reflux device having a nitrogen introduction device at the top is IPA. 330 parts of (2-propanol) and 320 parts of MEK (2-butanone) were charged, and the inside of the reaction vessel was purged with nitrogen while stirring. The temperature was raised to 80 ° C. while maintaining the inside of the reaction vessel in a nitrogen atmosphere, and from a dropping device, 250 parts of styrene, 250 parts of benzyl methacrylate, 129 parts of butyl methacrylate, 2,2′-azobis (2-methylbutyro (Nitrile) 100 parts mixed solution (a-1), ion-exchanged water 250 parts, IPA 100 parts, 2-acrylamido-2-methylpropanesulfonic acid 221 parts and acrylamide 150 parts mixed liquid (a-2), It was dripped in parallel over 3 hours. After completion of the dropping, the reaction was further continued for 4 hours at the same temperature. Thereafter, the inside of the reaction vessel was cooled to 60 ° C., and an aqueous solution in which 40.4 parts of lithium hydroxide monohydrate was dissolved in 567 parts of ion-exchanged water was added. Thereafter, an aqueous solution obtained by dissolving 1,800 parts of ethylene carbonate in 1200 parts of ion-exchanged water was added and mixed until uniform, and then IPA, MEK and some water were kept at the same temperature and the non-volatile content was reduced to about 25%. The solution was distilled off under reduced pressure until a solution (resin solution A-5) of a copolymer (resin 5) having a non-volatile content of 27.26%, a water content of 27.72%, an acid value of 60, and a pH of 7.0 was obtained. The nonvolatile content was measured by drying for 6 hours with a dryer at 140 ° C. The moisture was measured with a Karl Fischer moisture meter (Mitsubishi Chemical automatic moisture measuring device KF-07).

<Synthesis Example 6> (Resin 6; sulfonic acid group-containing resin neutralized salt)
The reaction vessel of the automatic polymerization reaction device (polymerization tester DSL-2AS type, manufactured by Sakai Sangyo Co., Ltd.) having a reaction vessel equipped with a stirring device, a dropping device, a temperature sensor, and a reflux device having a nitrogen introduction device at the top is IPA. 560 parts of (2-propanol) and 200 parts of MEK (2-butanone) were charged, and the inside of the reaction vessel was purged with nitrogen while stirring. After raising the temperature in the reaction vessel to 80 ° C. while maintaining a nitrogen atmosphere, mixing of 300 parts of styrene, 294 parts of benzyl methacrylate, and 100 parts of 2,2′-azobis (2-methylbutyronitrile) from a dropping device. Liquid (a-1) and a mixed liquid (a-2) of 250 parts of ion-exchanged water, 200 parts of IPA, and 406 parts of 2-acrylamido-2-methylpropanesulfonic acid were dropped in parallel over 3 hours. After completion of the dropping, the reaction was further continued for 4 hours at the same temperature. Thereafter, the inside of the reaction vessel was cooled to 60 ° C., and an aqueous solution in which 74.0 parts of lithium hydroxide monohydrate was dissolved in 1039 parts of ion-exchanged water was added. Thereafter, an aqueous solution obtained by dissolving 1,800 parts of ethylene carbonate in 1200 parts of ion-exchanged water was added and mixed until uniform, and then IPA, MEK and some water were kept at the same temperature and the non-volatile content was reduced to about 25%. The solution was distilled off under reduced pressure to obtain a solution (resin solution A-6) of a copolymer (resin 6) having a nonvolatile content of 23.25%, a water content of 33.49%, an acid value of 110, and a pH of 6.9. The nonvolatile content was measured by drying for 6 hours with a dryer at 140 ° C. The moisture was measured with a Karl Fischer moisture meter (Mitsubishi Chemical automatic moisture measuring device KF-07).

<Synthesis Example 7> (Resin 7; sulfonic acid group-containing resin neutralized salt)
The reaction vessel of the automatic polymerization reaction device (polymerization tester DSL-2AS type, manufactured by Sakai Sangyo Co., Ltd.) having a reaction vessel equipped with a stirring device, a dropping device, a temperature sensor, and a reflux device having a nitrogen introduction device at the top is IPA. 440 parts of (2-propanol) and 200 parts of MEK (2-butanone) were charged, and the inside of the reaction vessel was purged with nitrogen while stirring. The temperature was raised to 80 ° C. while maintaining the inside of the reaction vessel in a nitrogen atmosphere, and then from a dropping device, 400 parts of styrene, 250 parts of benzyl methacrylate, 129 parts of butyl acrylate, 2,2′-azobis (2-methylbutyro (Nitrile) 100 parts of mixture (a-1) and ion exchanged water 250 parts, IPA 100 parts, 2-acrylamido-2-methylpropanesulfonic acid 221 parts of mixture (a-2) over 3 hours Parallel dripping. After completion of the dropping, the reaction was further continued for 4 hours at the same temperature. Thereafter, the inside of the reaction vessel was cooled to 60 ° C., and an aqueous solution in which 40.4 parts of lithium hydroxide monohydrate was dissolved in 567 parts of ion-exchanged water was added. Thereafter, an aqueous solution obtained by dissolving 1,800 parts of ethylene carbonate in 1200 parts of ion-exchanged water was added and mixed until uniform, and then IPA, MEK and some water were kept at the same temperature and the non-volatile content was reduced to about 25%. The solution was distilled off under reduced pressure to obtain a solution (resin solution A-7) of a copolymer (resin 7) having a nonvolatile content of 22.61%, a water content of 37.93%, an acid value of 60, and a pH of 6.3. The nonvolatile content was measured by drying for 6 hours with a dryer at 140 ° C. The moisture was measured with a Karl Fischer moisture meter (Mitsubishi Chemical automatic moisture measuring device KF-07).

<Synthesis Example 8> (Resin 8; sulfonic acid group-containing resin neutralized salt)
The reaction vessel of the automatic polymerization reaction device (polymerization tester DSL-2AS type, manufactured by Sakai Sangyo Co., Ltd.) having a reaction vessel equipped with a stirring device, a dropping device, a temperature sensor, and a reflux device having a nitrogen introduction device at the top is IPA. 560 parts of (2-propanol) and 200 parts of MEK (2-butanone) were charged, and the inside of the reaction vessel was purged with nitrogen while stirring. The temperature was raised to 80 ° C. while maintaining the inside of the reaction vessel in a nitrogen atmosphere, and then from a dropping device, 400 parts of styrene, 250 parts of benzyl methacrylate, 129 parts of butyl acrylate, 2,2′-azobis (2-methylbutyro (Nitrile) 100 parts of mixture (a-1) and ion exchange water 150 parts, IPA 300 parts, 2-acrylamido-2-methylpropanesulfonic acid 221 parts of mixture (a-2) over 3 hours Parallel dripping. After completion of the dropping, the reaction was further continued for 4 hours at the same temperature. Thereafter, the inside of the reaction vessel was cooled to 60 ° C., and an aqueous solution in which 38.5 parts of sodium hydroxide was dissolved in 567 parts of ion-exchanged water was added. Thereafter, an aqueous solution obtained by dissolving 1,800 parts of ethylene carbonate in 1200 parts of ion-exchanged water was added and mixed until uniform, and then IPA, MEK and some water were kept at the same temperature and the non-volatile content was reduced to about 25%. The solution was distilled off under reduced pressure until a solution (resin solution A-8) of a copolymer (resin 8) having a nonvolatile content of 23.56%, a water content of 33.87%, an acid value of 60, and a pH of 6.8 was obtained. The nonvolatile content was measured by drying for 6 hours with a dryer at 140 ° C. The moisture was measured with a Karl Fischer moisture meter (Mitsubishi Chemical automatic moisture measuring device KF-07).

<Synthesis Example 9> (Resin 9; sulfonic acid group-containing resin neutralized salt)
The reaction vessel of the automatic polymerization reaction device (polymerization tester DSL-2AS type, manufactured by Sakai Sangyo Co., Ltd.) having a reaction vessel equipped with a stirring device, a dropping device, a temperature sensor, and a reflux device having a nitrogen introduction device at the top is IPA. 330 parts of (2-propanol) and 320 parts of MEK (2-butanone) were charged, and the inside of the reaction vessel was purged with nitrogen while stirring. After raising the temperature inside the reaction vessel to 80 ° C. while maintaining a nitrogen atmosphere, 350 parts of styrene, 250 parts of benzyl methacrylate, 79 parts of butyl acrylate, 50 parts of N, N-dimethylacrylamide, and polyethylene oxide mono are added from a dropping device. A mixed solution (a-1) of 50 parts of methacrylic acid ester (Blemmer PE-350, manufactured by NOF Corporation), 100 parts of 2,2′-azobis (2-methylbutyronitrile), 250 parts of ion-exchanged water, 100 parts of IPA Then, 221 parts of 2-acrylamido-2-methylpropanesulfonic acid (a-2) was dropped in parallel over 3 hours. After completion of the dropping, the reaction was further continued for 4 hours at the same temperature. Thereafter, the inside of the reaction vessel was cooled to 60 ° C., and an aqueous solution in which 40.4 parts of lithium hydroxide monohydrate was dissolved in 567 parts of ion-exchanged water was added. Thereafter, an aqueous solution obtained by dissolving 1,800 parts of ethylene carbonate in 1200 parts of ion-exchanged water was added and mixed until uniform, and then IPA, MEK and some water were kept at the same temperature and the non-volatile content was reduced to about 25%. The solution was distilled off under reduced pressure to obtain a solution (resin solution A-9) of a copolymer (resin 9) having a nonvolatile content of 26.02%, a water content of 39.93%, an acid value of 60, and a pH of 6.3. The nonvolatile content was measured by drying for 6 hours with a dryer at 140 ° C. The moisture was measured with a Karl Fischer moisture meter (Mitsubishi Chemical automatic moisture measuring device KF-07).

<Synthesis Example 10> (Resin 10; sulfonic acid group-containing resin neutralized salt)
The reaction vessel of the automatic polymerization reaction device (polymerization tester DSL-2AS type, manufactured by Sakai Sangyo Co., Ltd.) having a reaction vessel equipped with a stirring device, a dropping device, a temperature sensor, and a reflux device having a nitrogen introduction device at the top is IPA. 330 parts of (2-propanol) and 320 parts of MEK (2-butanone) were charged, and the inside of the reaction vessel was purged with nitrogen while stirring. The temperature was raised to 80 ° C. while maintaining the inside of the reaction vessel in a nitrogen atmosphere, and then from a dropping device, 350 parts of styrene, 250 parts of benzyl methacrylate, 12.9 parts of butyl acrylate, methoxypoly (ethylene oxide) monomethacrylate ( (Bremen PME-1000, manufactured by NOF Corporation) 50 parts, 2,2'-azobis (2-methylbutyronitrile) 100 parts mixed solution (a-1), ion-exchanged water 250 parts, IPA 100 parts, 2-acrylamide A mixed liquid (a-2) of 221 parts of 2-methylpropanesulfonic acid was dropped in parallel over 3 hours. After completion of the dropping, the reaction was further continued for 4 hours at the same temperature. Thereafter, the inside of the reaction vessel was cooled to 60 ° C., and an aqueous solution in which 40.4 parts of lithium hydroxide monohydrate was dissolved in 567 parts of ion-exchanged water was added. Thereafter, an aqueous solution obtained by dissolving 1,800 parts of ethylene carbonate in 1200 parts of ion-exchanged water was added and mixed until uniform, and then IPA, MEK and some water were kept at the same temperature and the non-volatile content was reduced to about 25%. The solution was distilled off under reduced pressure until a solution (resin solution A-10) of a copolymer (resin 10) having a nonvolatile content of 25.84%, a moisture content of 34.55%, an acid value of 60, and a pH of 6.6 was obtained. The nonvolatile content was measured by drying for 6 hours with a dryer at 140 ° C. The moisture was measured with a Karl Fischer moisture meter (Mitsubishi Chemical automatic moisture measuring device KF-07).

[Comparison of neutralized and unneutralized salt]

<Preparation of pigment dispersion (S-1)>
Copper phthalocyanine C.I. I. Pigment Blue 15: 3 (Fastogen (registered trademark) Blue TGR, manufactured by Dainippon Ink & Chemicals, Inc.), modified acrylic block copolymer "DISPERBYK (registered trademark) 2001" (manufactured by Big Chemie Japan, Inc.) 8 parts (as a pigment dispersant), 20 parts of propylene carbonate, 152 parts of ethylene carbonate, and 200 parts of zirconia beads having a diameter of 0.5 mm are placed in a plastic container capable of sealing. Disperse for 1 hour with a paint shaker (manufactured by Toyo Seiki Co., Ltd.). The beads were filtered with a sheet mesh (200 mesh) to obtain a pigment dispersion (S-1). (Pigment content 10% by weight)

<Preparation Example 1>
Styrene / acrylic / maleic resin 20 parts of Hiros (registered trademark) X-228 (manufactured by Starlight Polymer) was dissolved in 40 parts of ethylene carbonate and 40 parts of propylene carbonate to obtain a resin solution A-11. To 12.5 parts of this resin solution A-11, 7 parts of propylene carbonate, 0.5 part of ethylene carbonate and 30 parts of pigment dispersion (S-1) were added and stirred to prepare an ink for ink jet recording (Preparation Example 1, Pigment). 6% and additional styrene / acrylic / maleic acid resin 5%).

<Preparation Example 2>
To 12.5 parts of resin solution A-11, 0.6 parts of diethanolamine and 6.9 parts of ion-exchanged water were mixed to make uniform, and then 30 parts of the pigment dispersion (S-1) was added and stirred. Ink for inkjet recording (Preparation Example 2, pigment 6%, diethanolamine neutralized salt of additional styrene / acrylic / maleic acid resin 5%, moisture 13.8%) was obtained. Since styrene / acrylic / maleic acid neutralized salt did not dissolve in the propylene carbonate / ethylene carbonate mixed solution, water was added. The effects of adding water were compared in Preparation Example 3 and Preparation Example 4 below.

<Preparation Example 3>
To a mixed solution obtained by adding 12 parts of propylene carbonate and 5.5 parts of ethylene carbonate to 2.5 parts of a modified acrylic block copolymer “DISPERBYK (registered trademark) 2001” (manufactured by Big Chemie Japan Co., Ltd.), a pigment dispersion ( S-1) Add 30 parts, stir, ink for inkjet recording (Preparation Example 3, 6% pigment, 5% modified acrylic block copolymer solution)

<Preparation Example 4>
To 2.5 parts of the modified acrylic block copolymer “DISPERBYK (registered trademark) 2001” (manufactured by Big Chemie Japan Co., Ltd.), 5.1 parts of propylene carbonate, 5.5 parts of ethylene carbonate, and 6.9 parts of ion-exchanged water are added. To the added mixed solution, 30 parts of the pigment dispersion (S-1) was added and stirred to prepare an inkjet recording ink (Preparation Example 4, pigment 6%, modified acrylic block copolymer solution 5%, moisture 13. 8%)

<Fixability evaluation>
Ink jet recording inks (Preparation Example 1 to Preparation Example 4) were prepared using bar coater no. 4 (ink application amount 5 to 6 g / m ² , and the ink application amount to the paper by inkjet when the entire surface is solidly applied is about 5 to 7 g / m ^{2 in} the calculation). When the topcoat (registered trademark) + ”(basis weight: 127.9 g / m ² , manufactured by Oji Paper Co., Ltd.) is subjected to ink development, and the developed color surface is rubbed with a finger over time, and the developed color surface does not rub. Time (minutes).

  Table 1 summarizes the composition and the fixing test results.

  In Table 1, PC represents propylene carbonate, and EC represents ethylene carbonate.

  As shown in Table 1, as shown in the comparison between Preparation Example 1 and Preparation Example 2, the fixing property is not obtained until the anionic group-containing polymer compound (styrene / acrylic / maleic acid resin) is neutralized with diethanolamine. Is expressed. Diethanolamine neutralized salt of styrene / acrylic / maleic acid resin did not dissolve in the PC / EC solution, so 13.8% of water was added. The effects of water were compared between Preparation Example 3 and Preparation Example 4. However, the fixing ability at the level of Preparation Example 2 cannot be achieved by adding the same amount of water. However, the diethanolamine salt (pH 8.24) of the carboxylic acid group-containing polymer compound of Preparation Example 2 cannot be used practically because it hydrolyzes ethylene carbonate or propylene carbonate.

[Dispersion resin and binder resin combination test (necessity of neutralized salt)]

<Preparation of pigment dispersion (S-2)>
In a mixing tank equipped with a cooling jacket, 460.7 parts of resin solution A-4 obtained in Synthesis Example 4; I. Pigment Blue 15: 3 (Fastogen (registered trademark) Blue TGR, manufactured by Dainippon Ink & Chemicals, Inc.) 250 parts and ethylene carbonate 851.8 parts were charged, stirred, and mixed.

  The mixed solution was passed through a dispersing device [SC mill “SC100 / 32 type”, manufactured by Mitsui Mining Co., Ltd.] filled with zirconia beads having a diameter of 0.3 mm, and dispersed by a circulation method for 4 hours. The number of revolutions of the dispersing device was 2700 rpm, and the temperature of the dispersion liquid was maintained at 35 ° C. to 45 ° C. or less by passing cold water through the cooling jacket.

  After completion of the dispersion, the dispersion stock solution is extracted from the mixing tank, and this dispersion is removed with a centrifugal separator (50A-IV type, Sakuma Seisakusho Co., Ltd.) over 6000 G for 30 minutes to obtain a pigment dispersion. (S-2) was obtained. The pigment content was 9.7%, the volume average dispersed particle size was 179.6 nm, the viscosity was 9.07 mPa · s, and the pH was 6.67.

<Example 1>
6.17 parts of pigment dispersion (S-2), 2.50 parts of resin solution A-2, 0.63 parts of ion exchange water, and 0.70 parts of ethylene carbonate were mixed to prepare an ink for ink jet recording. Using this ink for ink jet recording, coated paper “OK Topcoat (registered trademark) +” (basis weight 127.9 g / m ² , Oji Paper Co., Ltd.) using a bar coater No. 4 (ink application amount 5 to 6 g / m ² ). Color). When the color developed product was rubbed with a finger over time from the time of color development, the time during which the color developed portion did not rub was recorded, and it was 12 seconds.

<Comparative Example 1>
Ink for inkjet recording was prepared by mixing 6.17 parts of pigment dispersion (S-2), 2.38 parts of resin solution A-1, 0.51 part of ion-exchanged water, and 0.94 part of ethylene carbonate. Using this ink for ink jet recording, coated paper “OK Topcoat (registered trademark) +” (basis weight 127.9 g / m ² , Oji Paper Co., Ltd.) using a bar coater No. 4 (ink application amount 5 to 6 g / m ² ). Color). The color development was rubbed with a finger over time from the time of color development, and the time during which the color development portion did not rub was recorded, and it was 10 seconds.

<Comparative example 2>
6.17 parts of pigment dispersion (S-2), 1.25 parts of block copolymer “DISPERBYK (registered trademark) 190” (manufactured by Big Chemie Japan Co., Ltd.) which is a nonionic resin, 0.63 of ion-exchanged water Part and 1.95 parts of ethylene carbonate were mixed to prepare an ink for ink jet recording. Using this ink for ink jet recording, coated paper “OK Topcoat (registered trademark) +” (basis weight 127.9 g / m ² , Oji Paper Co., Ltd.) using a bar coater No. 4 (ink application amount 5 to 6 g / m ² ). Color). When the color developed part was rubbed with a finger over time from the time of color development and the time during which the developed color part was not rubbed was recorded, it was rubbed with the finger in 18 seconds, so that the fixing time was longer than 18 seconds. Conceivable.

<Preparation of pigment dispersion (S-3)>
In a mixing tank equipped with a cooling jacket, 142.1 parts of the resin solution A-3 obtained in Synthesis Example 3, 18 parts of a 25% aqueous potassium hydroxide solution, C.I. I. Pigment Blue 15: 3 (Fastogen (registered trademark) Blue TGR, manufactured by Dainippon Ink and Chemicals, Inc.) 250 parts, ion-exchanged water 904.9 parts, MEK (2-butanone) 57.9 parts, Mixed. Here, the amount of each charged is such that the copolymer has a non-volatile content of 30% with respect to the pigment, and the 25% aqueous potassium hydroxide solution has the acid value of the styrene-acrylic copolymer 100% neutralized. Amount.

  The mixed solution was passed through a dispersing device [SC mill “SC100 / 32 type”, manufactured by Mitsui Mining Co., Ltd.] filled with zirconia beads having a diameter of 0.3 mm, and dispersed by a circulation method for 4 hours. The number of revolutions of the dispersing device was 2700 rpm, and the temperature of the dispersion liquid was kept at 40 ° C. or less through the cooling jacket through cold water.

  After the dispersion, the dispersion stock solution was extracted from the mixing tank, and then the mixing tank and the dispersion device flow path were washed with 1,000 parts of water, and the diluted dispersion liquid was obtained together with the dispersion stock solution. The diluted dispersion was put into a glass distillation apparatus, and the whole amount of methyl ethyl ketone and a part of water were removed by atmospheric distillation.

  The dispersion from which methyl ethyl ketone was removed was cooled, and then 10% hydrochloric acid was added dropwise with stirring to adjust the pH to 4.5, and then the solid content was filtered with a Nutsche filter and washed with water. Take the cake in a container, add 20% potassium hydroxide aqueous solution and water in such an amount that the acid value of the styrene-acrylic copolymer is 90% neutralized, and add a dispersion stirrer [TK Homodispa Model 20, Special Machine Industries Co., Ltd. The product was dispersed again.

  From this dispersion, coarse particles were removed with a centrifuge [50A-IV type, Sakuma Seisakusho] over 6000 G for 30 minutes to obtain a pigment dispersion (S-3) (pigment content 19. 28%).

<Comparative Example 3>
Ink for inkjet recording was prepared by mixing 3.11 parts of pigment dispersion (S-3), 2.38 parts of resin solution A-1 and 4.51 parts of ethylene carbonate. Using this ink for ink jet recording, coated paper “OK Topcoat (registered trademark) +” (basis weight 127.9 g / m ² , Oji Paper Co., Ltd.) using a bar coater No. 4 (ink application amount 5 to 6 g / m ² ). Color). When the color developed product was rubbed with a finger over time from the time of color development and the time during which the developed color portion did not rub was recorded, it was 8 seconds.

<Comparative example 4>
Ink for inkjet recording was prepared by mixing 3.11 parts of pigment dispersion (S-3), 2.50 parts of resin solution A-2, 1.13 parts of ion-exchanged water, and 3.26 parts of ethylene carbonate. Using this ink for ink jet recording, coated paper “OK Topcoat (registered trademark) +” (basis weight 127.9 g / m ² , Oji Paper Co., Ltd.) using a bar coater No. 4 (ink application amount 5 to 6 g / m ² ). Color). When the color developed product was rubbed with a finger over time from the time of color development, the time during which the color developed portion did not rub was recorded, and it was 12 seconds.

<Comparative Example 5>
3.11 parts of pigment dispersion (S-3), 1.25 parts of a block copolymer “DISPERBYK (registered trademark) 190” (manufactured by Big Chemie Japan Co., Ltd.) which is a nonionic resin, 0.12 of ion-exchanged water Part and ethylene carbonate 5.52 parts were mixed to prepare an ink for inkjet recording. Using this ink for ink jet recording, coated paper “OK Topcoat (registered trademark) +” (basis weight 127.9 g / m ² , Oji Paper Co., Ltd.) using a bar coater No. 4 (ink application amount 5 to 6 g / m ² ). Color). When the color developed part was rubbed with a finger over time from the time of color development and the time during which the developed color part was not rubbed was recorded, it was rubbed with the finger in 18 seconds, so that the fixing time was longer than 18 seconds. Conceivable.

<Preparation of pigment dispersion (S-4)>
C. I. Pigment Blue 15: 3 (Fastogen (registered trademark) Blue TGR, manufactured by Dainippon Ink & Chemicals, Incorporated) 2.00 parts, block copolymer “DISPERBYK (registered trademark) 190” which is a nonionic resin (BIC Chemie Japan) 2.00 parts, 1.32 parts of ethylene carbonate, 2.80 parts of ion-exchanged water, and 20 parts of zirconia beads having a diameter of 0.5 mm are placed in a plastic container that can be sealed. Disperse for 1 hour with a paint shaker (manufactured by Toyo Seiki Co., Ltd.). The beads were filtered with a sheet mesh (200 mesh) to obtain a pigment dispersion (S-4). (Pigment content 10% by weight)

<Comparative Example 6>
Ink for inkjet recording was prepared by mixing 6.00 parts of pigment dispersion (S-4), 2.38 parts of resin solution A-1, 1.13 parts of ion-exchanged water, and 0.49 parts of ethylene carbonate. Using this ink for ink jet recording, coated paper “OK Topcoat (registered trademark) +” (basis weight 127.9 g / m ² , Oji Paper Co., Ltd.) using a bar coater No. 4 (ink application amount 5 to 6 g / m ² ). Color). When the color developed part was rubbed with a finger over time from the time of color development and the time during which the developed color part was not rubbed was recorded, it was rubbed with the finger in 18 seconds, so that the fixing time was longer than 18 seconds. Conceivable.

<Comparative Example 7>
Ink for inkjet recording was prepared by mixing 6.00 parts of pigment dispersion (S-4), 2.50 parts of resin solution A-2, 1.25 parts of ion-exchanged water, and 0.25 parts of ethylene carbonate. Using this ink for ink jet recording, coated paper “OK Topcoat (registered trademark) +” (basis weight 127.9 g / m ² , Oji Paper Co., Ltd.) using a bar coater No. 4 (ink application amount 5 to 6 g / m ² ). Color). When the color developed part was rubbed with a finger over time from the time of color development and the time during which the developed color part was not rubbed was recorded, it was rubbed with the finger in 18 seconds, so that the fixing time was longer than 18 seconds. Conceivable.

<Comparative Example 8>
6.00 parts of pigment dispersion (S-4), 1.25 parts of block copolymer “DISPERBYK (registered trademark) 190” (manufactured by Big Chemie Japan Co., Ltd.) which is a nonionic resin, 1.25 parts of ion-exchanged water Part and ethylene carbonate 1.50 parts were mixed, and the ink for inkjet recording was created. Using this ink for ink jet recording, coated paper “OK Topcoat (registered trademark) +” (basis weight 127.9 g / m ² , Oji Paper Co., Ltd.) using a bar coater No. 4 (ink application amount 5 to 6 g / m ² ). Color). When the color developed part was rubbed with a finger over time from the time of color development and the time during which the developed color part was not rubbed was recorded, it was rubbed with the finger in 18 seconds, so that the fixing time was longer than 18 seconds. Conceivable.

  Table 2 shows the formulations of the inks prepared in Example 1 and Comparative Examples 1-8.

  In Table 2, EC represents ethylene carbonate. "Carboxylic acid" and "sulfonic acid" in the table represent "carboxylic acid group-containing resin neutralized salt" and "sulfonic acid group-containing resin neutralized salt" (neutralized salt neutralized with a base), respectively. Yes.

Table 3 summarizes the results of the fixability test of the inks of Table 2 prepared in Example 1 and Comparative Examples 1 to 8 from the relationship between the dispersion resin and the binder resin. The unit is seconds. In Table 3, “carboxylic acid” and “sulfonic acid” represent “carboxylic acid group-containing resin neutralized salt” and “sulfonic acid group-containing resin neutralized salt” (neutralized salt neutralized with a base). . The fixability test was conducted using a bar coater no. It is a result when using 4 (ink application amount 5-6 g / m < ² >).

  Among the inks prepared in Example 1 and Comparative Examples 1 to 8, when the neutralized salt of an anionic group-containing organic polymer compound having a carboxylic acid or sulfonic acid group is used for both the dispersion resin and the binder resin. The fixability has been improved dramatically. When neutralized salts of carboxylic acids are used, there is a practical problem because ethylene carbonate and propylene carbonate are hydrolyzed.

<Preparation of pigment dispersion (S-5)>
Carbon black (# 45, manufactured by Mitsubishi Chemical Corporation) 4.00 parts, surface-treated carbon “TPX741” (manufactured by Cabot Specialty Chemicals Inc.) 0.20 parts, resin solution A-5 5.87 parts, ion Place 5.33 parts of exchange water, 7.80 parts of ethylene carbonate, and 100 parts of zirconia beads having a diameter of 0.5 mm in a plastic container that can be sealed. Disperse for 1 hour with a paint shaker (manufactured by Toyo Seiki Co., Ltd.). To this dispersion, 4.64 parts of ion-exchanged water and 10.83 parts of ethylene carbonate were added and stirred, and the beads were filtered with a sheet mesh (200 mesh) to obtain a pigment dispersion (S-5). (Pigment content 10.9% by weight, moisture 30.0%)

<Example 2>
Ink for inkjet recording (pigment content 6%, moisture 27.5%) by mixing 5.80 parts of pigment dispersion (S-5), 3.01 parts of resin solution A-6, 1.19 parts of ethylene carbonate It was created. The ink for ink jet recording was designated as bar coater No. 6 (ink application amount: 10 to ¹² g / m ² , No. 6 is more stringent as a fixing test because the ink application amount is larger than No. 4) Coat (registered trademark) + ”(basis weight: 127.9 g / m ² , manufactured by Oji Paper Co., Ltd.). The color developed product was rubbed with a finger over time from the time of color development, and the time when the developed color portion was not rubbed was recorded, and it was 60 to 70 seconds.

<Preparation of pigment dispersion (S-6)>
C. I. Pigment Yellow 74 (Fast Yellow 7413, manufactured by Sanyo Dye Co., Ltd.) 4.00 parts, surface treated pigment “TPX3004” (manufactured by Cabot Specialty Chemicals Inc.) 0.20 parts, resin solution A-5 2.93 parts Then, 5.19 parts of ion-exchanged water, 7.68 parts of ethylene carbonate, and 100 parts of zirconia beads having a diameter of 0.5 mm are placed in a plastic container that can be sealed. Disperse for 1 hour with a paint shaker (manufactured by Toyo Seiki Co., Ltd.). To this dispersion, 4.00 parts of ion-exchanged water and 9.33 parts of ethylene carbonate were added and stirred, and the beads were filtered with a sheet mesh (200 mesh) to obtain a pigment dispersion (S-6). (Pigment content 12.6% by weight, moisture 30.0%)

<Example 3>
5.00 parts of pigment dispersion (S-6), 3.53 parts of resin solution A-6, 0.07 parts of ion-exchanged water and 1.40 parts of ethylene carbonate were mixed to prepare an ink for inkjet recording (pigment content 6). %, Moisture 27.5%). The ink for ink jet recording was designated as bar coater No. 6 (ink application amount: 10 to ¹² g / m ² , No. 6 is more stringent as a fixing test because the ink application amount is larger than No. 4) Coat (registered trademark) + ”(basis weight: 127.9 g / m ² , manufactured by Oji Paper Co., Ltd.). The color developed product was rubbed with a finger over time from the time of color development, and the time when the developed color portion was not rubbed was recorded, and it was 50 to 60 seconds.

<Preparation of pigment dispersion (S-7)>
C. I. Pigment Red 122 (Fastogen (registered trademark) Super Magenta RG, manufactured by Dainippon Ink & Chemicals, Inc.) 4.00 parts, surface treatment pigment “TPX3006” (manufactured by Cabot Specialty Chemicals, Inc.), 0.2 parts, resin 6.19 parts of Solution A-10, 7.14 parts of ion exchange water, 5.67 parts of ethylene carbonate, and 100 parts of zirconia beads having a diameter of 0.5 mm are placed in a plastic container that can be sealed. Disperse for 1 hour with a paint shaker (manufactured by Toyo Seiki Co., Ltd.). From this dispersion, beads were filtered with a sheet mesh (200 mesh) to obtain a pigment dispersion (S-7). (Pigment content 18.1% by weight, moisture 40.0%)

<Example 4>
3.48 parts of pigment dispersion (S-7), 0.70 part of resin solution A-10, 2.37 parts of ion-exchanged water, and 3.46 parts of ethylene carbonate were mixed to prepare an ink for inkjet recording (pigment content 6). %, Moisture 40.0%). The ink for ink jet recording was designated as bar coater No. 6 (ink application amount: 10 to ¹² g / m ² , No. 6 is more stringent as a fixing test because the ink application amount is larger than No. 4) Coat (registered trademark) + ”(basis weight: 127.9 g / m ² , manufactured by Oji Paper Co., Ltd.). The color development product was rubbed with a finger over time from the time of color development, and the time when the color development portion did not rub was recorded, and it was 80 seconds.

<Preparation of pigment dispersion (S-8)>
In a mixing tank equipped with a cooling jacket, 315.6 parts of resin solution A-5 obtained in Synthesis Example 5 and C.I. I. Pigment Blue 15: 3 (Fastogen (registered trademark) Blue TGR, manufactured by Dainippon Ink & Chemicals, Inc.) 200 parts, ethylene carbonate 278.9 parts, and ion-exchanged water 605.6 parts were stirred and mixed.

  The mixed solution was passed through a dispersing device [SC mill “SC100 / 32 type”, manufactured by Mitsui Mining Co., Ltd.] filled with zirconia beads having a diameter of 0.3 mm, and dispersed for 2 hours by a circulation method. The number of revolutions of the dispersing device was 2700 revolutions / minute, and the temperature of the dispersion liquid was maintained at 35 ° C. to 45 ° C. or less through cooling water through the cooling jacket.

  After the completion of dispersion, 1280 parts of the dispersion liquid was taken out from the mixing tank. 242.8 parts of ethylene carbonate was added to this dispersion and transferred to a distillation kettle to distill off 421.1 parts of water. From this dispersion, coarse particles were removed with a centrifuge [50A-IV type, Sakuma Seisakusho] over 6000 G for 30 minutes to obtain a pigment dispersion (S-8). The pigment content was 15.67%, the water content was 26.82%, the volume average dispersed particle size was 159.8 nm, the viscosity was 10.02 mPa · s, and the pH was 6.49.

<Example 5>
3.83 parts of pigment dispersion (S-8), 2.57 parts of resin solution A-5, 1.26 parts of ion-exchanged water and 2.34 parts of ethylene carbonate were mixed to prepare an ink for inkjet recording (pigment content 6). %, Moisture 30.0%). The ink for ink jet recording was designated as bar coater No. 6 (ink application amount: 10 to ¹² g / m ² , No. 6 is more stringent as a fixing test because the ink application amount is larger than No. 4) Coat (registered trademark) + ”(basis weight: 127.9 g / m ² , manufactured by Oji Paper Co., Ltd.). The color development was rubbed with a finger over time from the time of color development, and the time during which the color development portion did not rub was recorded, and it was 120 seconds.

<Example 6>
3.83 parts of pigment dispersion (S-8), 3.01 parts of resin solution A-6, 0.96 parts of ion exchange water, and 2.20 parts of ethylene carbonate were mixed to prepare an ink for ink jet recording (pigment content 6). %, Moisture 30.0%). The ink for ink jet recording was designated as bar coater No. 6 (ink application amount: 10 to ¹² g / m ² , No. 6 is more stringent as a fixing test because the ink application amount is larger than No. 4) Coat (registered trademark) + ”(basis weight: 127.9 g / m ² , manufactured by Oji Paper Co., Ltd.). The color development was rubbed with a finger over time from the time of color development, and the time during which the color development portion did not rub was recorded, and it was 180 seconds.

<Example 7>
3.83 parts of pigment dispersion (S-8), 3.10 parts of resin solution A-7, 0.80 parts of ion-exchanged water and 2.28 parts of ethylene carbonate were mixed to prepare an ink for inkjet recording (pigment content 6). %, Moisture 30.0%). The ink for ink jet recording was designated as bar coater No. 6 (ink application amount: 10 to ¹² g / m ² , No. 6 is more stringent as a fixing test because the ink application amount is larger than No. 4) Coat (registered trademark) + ”(basis weight: 127.9 g / m ² , manufactured by Oji Paper Co., Ltd.). The color developed product was rubbed with a finger over time from the time of color development, and the time when the developed color portion was not rubbed was recorded, and it was 50 to 60 seconds.

<Example 8>
3.83 parts of pigment dispersion (S-8), 2.97 parts of resin solution A-8, 0.97 parts of ion-exchanged water, and 2.23 parts of ethylene carbonate were mixed to prepare an ink for inkjet recording (pigment content 6). %, Moisture 30.0%). The ink for ink jet recording was designated as bar coater No. 6 (ink application amount: 10 to ¹² g / m ² , No. 6 is more stringent as a fixing test because the ink application amount is larger than No. 4) Coat (registered trademark) + ”(basis weight: 127.9 g / m ² , manufactured by Oji Paper Co., Ltd.). The color development was rubbed with a finger over time from the time of color development, and the time during which the color development portion did not rub was recorded, and it was 60 seconds.

<Example 9>
3.83 parts of pigment dispersion (S-8), 2.69 parts of resin solution A-9, 0.90 parts of ion-exchanged water, and 2.58 parts of ethylene carbonate were mixed to prepare an ink for inkjet recording (pigment content 6). %, Moisture 30.0%). The ink for ink jet recording was designated as bar coater No. 6 (ink application amount: 10 to ¹² g / m ² , No. 6 is more stringent as a fixing test because the ink application amount is larger than No. 4) Coat (registered trademark) + ”(basis weight: 127.9 g / m ² , manufactured by Oji Paper Co., Ltd.). The color development was rubbed with a finger over time from the time of color development, and the time during which the color development portion did not rub was recorded, and it was 180 seconds.

  In Table 4, EC represents ethylene carbonate.

It should be noted that the ink of Example 6 was coated with a bar coater No. 4 (coating amount 5-6 g / m ² ) was used to develop the color on coated paper “OK Top Coat (registered trademark) +” (basis weight 127.9 g / m ² , manufactured by Oji Paper Co., Ltd.) and fixability When tested, the fixing time (s) was 15-18 seconds.

<Example 10>
3.83 parts of pigment dispersion (S-8), 2.71 parts of resin solution A-10, 1.04 parts of ion-exchanged water, 2.43 parts of ethylene carbonate were mixed to prepare an ink for inkjet recording (pigment content 6). %, Moisture 30.0%). The ink for ink jet recording was designated as bar coater No. 6 (ink application amount: 10 to ¹² g / m ² , No. 6 is more stringent as a fixing test because the ink application amount is larger than No. 4) Coat (registered trademark) + ”(basis weight: 127.9 g / m ² , manufactured by Oji Paper Co., Ltd.). The color developed product was rubbed with a finger over time from the time of color development, and the time when the developed color portion was not rubbed was recorded, and it was 40 to 50 seconds.

<Example 11>
Pigment dispersion (S-8) 3.83 parts, resin solution A-10 2.71 parts, ion-exchanged water 1.04 parts, ethylene carbonate 1.93 parts, propylene carbonate 0.50 parts are mixed and inkjet A recording ink (pigment content 6%, moisture 30.0%) was prepared. The ink for ink jet recording was designated as bar coater No. 6 (ink application amount: 10 to ¹² g / m ² , No. 6 is more stringent as a fixing test because the ink application amount is larger than No. 4) Coat (registered trademark) + ”(basis weight: 127.9 g / m ² , manufactured by Oji Paper Co., Ltd.). The color development was rubbed with a finger over time from the time of color development, and the time during which the color development portion did not rub was recorded, and it was 60 seconds.

<Example 12>
3.83 parts of pigment dispersion (S-8), 2.71 parts of resin solution A-10, 1.04 parts of ion-exchanged water, 1.93 parts of ethylene carbonate, and 0.50 parts of sulfolane are mixed to perform ink jet recording. Ink (pigment content 6%, moisture 30.0%) was prepared. The ink for ink jet recording was designated as bar coater No. 6 (ink application amount: 10 to ¹² g / m ² , No. 6 is more stringent as a fixing test because the ink application amount is larger than No. 4) Coat (registered trademark) + ”(basis weight: 127.9 g / m ² , manufactured by Oji Paper Co., Ltd.). The color developed product was rubbed with a finger over time from the time of color development, and the time when the developed color portion was not rubbed was recorded, and it was 60 to 70 seconds.

<Example 13>
3.83 parts of pigment dispersion (S-8), 2.71 parts of resin solution A-10, 1.04 parts of ion-exchanged water, 1.43 parts of ethylene carbonate, and 1.00 parts of sulfolane are mixed to perform ink jet recording. Ink (pigment content 6%, moisture 30.0%) was prepared. The ink for ink jet recording was designated as bar coater No. 6 (ink application amount: 10 to ¹² g / m ² , No. 6 is more stringent as a fixing test because the ink application amount is larger than No. 4) Coat (registered trademark) + ”(basis weight: 127.9 g / m ² , manufactured by Oji Paper Co., Ltd.). The color development was rubbed with a finger over time from the time of color development, and the time during which the color development portion did not rub was recorded, and it was 150 to 160 seconds.

<Example 14>
Pigment dispersion (S-8) 3.83 parts, resin solution A-10 2.71 parts, ion-exchanged water 1.04 parts, ethylene carbonate 1.93 parts, 1,3-dimethyl-2-imidazolidinone 0 .50 parts were mixed to prepare an ink for inkjet recording (pigment content 6%, moisture 30.0%). The ink for ink jet recording was designated as bar coater No. 6 (ink application amount: 10 to ¹² g / m ² , No. 6 is more stringent as a fixing test because the ink application amount is larger than No. 4) Coat (registered trademark) + ”(basis weight: 127.9 g / m ² , manufactured by Oji Paper Co., Ltd.). The color developed product was rubbed with a finger over time from the time of color development, and the time when the developed color portion was not rubbed was recorded, and it was 60 to 70 seconds.

<Curl test>
The ink for inkjet recording obtained in Example 10 to Example 14 was applied to a coated paper “OK Top Coat (registered trademark) +” (basis weight 127.9 g / m ² , manufactured by Oji Paper Co., Ltd.) cut into 4 cm square. , Bar coater No. The color was developed at 6 (ink application amount: 10 to ¹² g / m ² ). At this time, the weight of the paper before color development is measured, the weight is measured again immediately after the color development, and the weight of the ink developed on the paper is measured. From this, the coating amount (g / cm ² ) per unit area was calculated. Thereafter, the developed test piece is allowed to stand at room temperature for 10 minutes, and the deformed height (cm) is measured after 10 minutes. The deformation amount was divided by the coating amount to obtain a curl rate (cm ³ / g).

Application amount (g / cm ² ) = {weight immediately after color development (g) −weight before color development (g)} / paper area (cm ² )

Curling rate (cm ³ / g) = deformation height (cm) / application amount (g / cm ² )

In Table 5, the following abbreviations were used.
EC: ethylene carbonate PC: propylene carbonate sulfolane: tetrahydrothiophene-1,1-dioxide DMI: 1,3-dimethyl-2-imidazolidinone

  As is apparent from the results in Table 5, blending a solvent is effective in improving curl.

  Further, in order to examine the storage stability of the ink, the volume average particle diameter (μm) and the viscosity (mPa · s) of the inks of Examples 2 to 14 and the respective inks were allowed to stand at 70 ° C. for 1 day. The volume average particle diameter (μm) and the viscosity (mPa · s) were measured. As is apparent from the results of Tables 4 and 5, even after 1 day at 70 ° C., no significant changes were observed in the volume average particle size (μm) and viscosity (mPa · s), and sufficient storage was achieved. Showed stability.

<Example IJ-1>
With respect to the ink for ink jet recording of Example 10, the following test was performed using an ink jet recording evaluation apparatus equipped with an ink jet head driven by a piezo element having a nozzle resolution of 180 dpi × 180 dpi.

(1) Curl test Solid printing was carried out on the A4 size of coated paper “OK Top Coat (registered trademark) +” (basis weight 127.9 g / m ² , manufactured by Oji Paper Co., Ltd.) with a 1 cm margin in the vertical and horizontal directions. The print sample was placed on a horizontal table with the print surface facing up, the change with time of the print sample was observed, and the following evaluation criteria (A, B, C) were used.

A: The average value of deformation at the four corners of the sample is left below 1 cm even after standing for 1 week. B: The average value of deformation at the four corners of the sample is 1 cm or more and less than 5 cm after being left for 1 week. Later, the average value of deformation at the four corners of the sample is 5 cm or more.

At this time, the amount of ink discharged was adjusted to 7.0 mg / inch ² and the amount of ink deposited on the paper was about 580 mg, and the result was A.

(2) Cock ring 720 × for coated paper “OK Top Coat (registered trademark) +” (basis weight 127.9 g / m ² , manufactured by Oji Paper Co., Ltd.) under the same ink discharge conditions as in the test of (1). A patch of 10 cm × 10 cm solid printing was printed at 720 dpi, and the degree of unevenness (cockling) of the printed paper was measured using a laser displacement meter LK-010 (manufactured by Keyence Corporation), and the following evaluation criteria (A, B, C, D).

A: Less than 1.0 mm B: 1.0 mm or more and less than 1.5 mm C: 1.5 mm or more and less than 2.0 mm D: 2.0 mm or more

  The evaluation result at this time was B.

(3) Fixability 720 × for coated paper “OK Topcoat (registered trademark) +” (basis weight 127.9 g / m ² , manufactured by Oji Paper Co., Ltd.) under the same ink ejection conditions as in the test of (1). When printing a 10 cm × 10 cm solid patch at 720 dpi, rubbing the printed surface with fingers at 10 second intervals immediately after printing, visually observing the state of the printed surface, and measuring the time until the ink does not rub at all, It was 70 seconds.

(4) Discharge stability Using the above-described inkjet evaluation apparatus, solid printing and line drawing patterns were continuously printed. The number of cleanings of the printer nozzle that is performed as a return operation to normal printing when ink dots are missing or flying bent within 100 pages of printing was evaluated and determined based on the following criteria (A, B, C).

A: cleaning 0 times B: cleaning 1 or 2 times C: cleaning 3 times or more

  The evaluation result at this time was A.

(5) Clogging recovery property After continuously printing for 10 minutes using the above-described inkjet evaluation apparatus and confirming that ink is normally ejected from all nozzles, the inkjet head is removed and the environment at 40 ° C. I left it for a week. After leaving, the cleaning operation was repeated until all nozzles ejected at the same level as the initial stage, and the ease of recovery was evaluated according to the following criteria (A, B, C).

A: Recovered to the same level as the initial state after less than 3 cleaning operations. B: Recovered to the same level as the initial level after 3 to 6 cleaning operations. C: Not recovered after 6 cleaning operations.

  The evaluation result at this time was B.

<Example IJ-2>
For the inkjet recording ink of Example 12, the same tests (1) to (5) as in Example IJ-1 were performed. As a result, the curl test result was A, and the cockling result was B. Yes, the fixability result was 100 seconds, the discharge stability result was A, and the clogging recovery property was A.

  The results of Examples IJ-1 and IJ-2 are summarized in Table 6.

  As described above, the ink for ink jet recording of the present invention is excellent in ejection stability even when used in an ink jet recording apparatus, and does not cause a problem of curling or cockling.

Claims (13)

An ink for inkjet recording containing at least carbon black or an organic pigment (a), a solvent (b) and a resin (c),
The solvent (b) contains ethylene carbonate or propylene carbonate as a main component, and the resin (c) contains a sulfonic acid group-containing organic polymer compound neutralized salt whose pH is adjusted to 6.0 to 7.0 as a main component. An ink for inkjet recording, comprising:   The ink for inkjet recording according to claim 1, wherein the solvent (b) contains ethylene carbonate or propylene carbonate as a main component and further contains water.   The ink for ink jet recording according to claim 1 or 2, wherein the sulfonic acid group-containing organic polymer compound neutralized salt contains 3% or more and less than 20% of the total amount of the ink.   The ink for inkjet recording according to any one of claims 1 to 3, wherein the sulfonic acid group-containing organic polymer compound neutralized salt has an acid value of 30 to 130.   The ink for inkjet recording according to any one of claims 1 to 4, wherein a counter cation of the sulfonic acid group-containing organic polymer compound neutralized salt is a lithium ion.   The ink for inkjet recording according to any one of claims 1 to 5, wherein the neutralized salt of a sulfonic acid group-containing organic polymer compound comprises a copolymer containing a sulfonic acid group-containing ethylenically unsaturated compound as a monomer.   The ink for inkjet recording according to any one of claims 1 to 6, wherein the neutralized salt of a sulfonic acid group-containing organic polymer compound comprises a copolymer containing 2-acrylamido-2-methylpropanesulfonic acid as a monomer. .   The ink for inkjet recording according to any one of claims 1 to 7, wherein the neutralized salt of a sulfonic acid group-containing organic polymer compound comprises a copolymer containing a polyoxyalkylene group-containing mono (meth) acrylate as a monomer. .   The ink for inkjet recording according to any one of claims 1 to 8, wherein the neutralized salt of a sulfonic acid group-containing organic polymer compound comprises a copolymer containing acrylamide and / or N, N-dimethylacrylamide as a monomer. .   The solvent (b) is a mixed solvent containing ethylene carbonate or propylene carbonate as a main component and further containing water in an amount of 20% to 40%, and the viscosity of the mixed solvent at 20 ° C. is 10 mPa · s or less. Item 10. The ink for inkjet recording according to any one of Items 1 to 9.   The pigment content in the inkjet recording ink is 0.5 wt% or more and 10 wt% or less, and the viscosity of the inkjet recording ink at 20 ° C is 20 mPa · s or less. 2. Ink for ink jet recording described in 1.   An ink set for ink jet recording using the ink for ink jet recording according to any one of claims 1 to 11.   An ink jet recording method using the ink for ink jet recording according to any one of claims 1 to 11 or the ink set for ink jet recording according to claim 12.