JP2020100736A - Method for producing aqueous dispersion of polyester resin particles - Google Patents

Abstract

To provide a method for producing an aqueous dispersion of polyester resin particles excellent in continuous ejection stability while maintaining excellent fixability by using an ink for inkjet recording, and to provide an ink for ink jet recording containing the aqueous dispersion obtained by the method.SOLUTION: There is provided [1] a method for producing an aqueous dispersion of polyester resin particles, including step 1 of mixing polyester resin a, an organic solvent, and an organic amine compound to obtain a solution of the polyester resin a neutralized with the organic amine compound and step 2 of supplying the solution obtained in step 1, which contains the neutralized polyester resin a, with an aqueous medium to invert the phase, and removing the organic solvent in the system so as to obtain aqueous dispersion of the polyester resin particles, and [2] an ink for inkjet recording which contains the aqueous dispersion obtained by the method [1] and a colorant.SELECTED DRAWING: None

Description

The present invention relates to a method for producing an aqueous dispersion of polyester resin particles, and an inkjet recording ink containing the aqueous dispersion obtained by the method.

The inkjet recording method is a method of directly ejecting ink droplets from a very fine nozzle onto a recording medium and adhering them to obtain a printed matter on which characters and images are recorded. In addition, plain paper can be used as a recording medium, and there are many advantages that it is non-contact with an object to be printed. Therefore, in addition to consumer printing for general consumers, in recent years, it has begun to be applied to commercial printing and industrial printing fields, and in addition to conventional plain paper and printing on superabsorbent recording media called copy paper, offset printing is also performed. Printing on recording media for commercial printing such as coated paper with low water absorption such as coated paper, non-water absorbent resin film such as polyvinyl chloride resin, polypropylene resin, polyester resin, etc. is required. ..

Patent Document 1 discloses a water-based ink containing a colorant and polyester resin particles for the purpose of providing a water-based ink for inkjet recording which is excellent in ink dischargeability, fixability to a recording medium such as coated paper, and the like. Have been described. Then, in the examples, the polyester resin and the anionic surfactant were mixed and dissolved with methyl ethyl ketone, and then ammonia water was mixed and subjected to dispersion treatment, further methyl ethyl ketone was distilled off under reduced pressure, and the solid content was adjusted with ion-exchanged water. , Obtaining an aqueous dispersion containing a polyester resin.
Patent Document 2 discloses a pigment coated with a water-insoluble resin, an amino alcohol, a water-soluble organic solvent, and water for the purpose of providing an ink composition having excellent dispersion stability and fixability on a recording medium. And an ink composition containing 5% by mass or more of resin fine particles is described. Then, in the examples, it is described that a mixed solution of Johncryl 537 manufactured by BASF Japan, sodium oleate, and ion-exchanged water was subjected to centrifugal treatment, and the supernatant was recovered to obtain a resin fine particle dispersion. Further, a carboxylate emulsifier, a sodium hydroxide aqueous solution, and 2,2′-azobis(2-amidinopropane) dihydrochloride are dissolved in water, and a monomer mixture of styrene, butyl acrylate, and acrylic acid is added. Then, it was heated at 70° C. for 2 hours and at 80° C. for 3 hours, cooled to room temperature, and then an aqueous sodium hydroxide solution was added to obtain a resin fine particle dispersion.
Patent Document 3 discloses an acid value of 10 mgKOH for the purpose of providing an ink composition for inkjet recording, which is excellent in water resistance and solvent resistance of a printed matter even when printed on a coated paper, and excellent in ejection stability. An ink composition for inkjet recording is described, which contains a resin of less than 1 g/g, an amino alcohol having a boiling point of 100 to 300° C., a pigment, and a solvent, and the resin is in an emulsion state. Then, in the examples, reactive surfactant, potassium persulfate, methacrylic acid, pure water is mixed, a mixture of butyl acrylate and methyl methacrylate is added dropwise to prepare a pre-emulsion, the reactive surfactant, It is described that a pre-emulsion was added dropwise to a mixture of potassium persulfate and pure water, heated and aged, cooled, and then N,N-dimethyl-2-aminoethanol was added to obtain a resin emulsion.

JP, 2014-88552, A JP, 2009-212252, A JP, 2005-101705, A

In the technique of Patent Document 1, when the nozzle portion of the inkjet recording apparatus is exposed to the atmosphere and the ejection property and the fixing property when printing is performed again after the printing is paused, the inkjet recording method continuously prints on a recording medium. The ejection stability (hereinafter, also referred to as “continuous ejection stability”) is not sufficient.
The ink composition of Patent Document 2 contains 5% by mass or more of acrylic resin fine particles, but the continuous ejection stability is not sufficient.
The ink composition of Patent Document 3 is a technique for improving the affinity between a resin and water or an aqueous solvent by adding amino alcohol to the ink to improve the ejection stability of the ink. There were cases where it was restricted.
INDUSTRIAL APPLICABILITY The present invention provides a method for producing an aqueous dispersion of polyester resin particles excellent in continuous ejection stability while maintaining excellent fixability by using the ink for inkjet recording, and an aqueous dispersion obtained by the method. An ink jet recording ink containing the same is provided.

The present inventors improve the dispersion stability of the polyester resin particles formed by adding an aqueous medium to a solution containing a polyester resin neutralized with an organic amine compound and performing phase inversion emulsification. We found that we could solve the problems. That is, the present invention relates to the following [1] and [2].
[1] A method for producing an aqueous dispersion of polyester resin particles, which comprises the following Step 1 and Step 2.
Step 1: A step of mixing the polyester resin a, the organic solvent, and the organic amine compound to obtain a solution of the polyester resin a neutralized with the organic amine compound Step 2: The neutralized solution obtained in Step 1 [2] A step of adding an aqueous medium to a solution containing the polyester resin a to invert the phase to remove the organic solvent in the system to obtain an aqueous dispersion of polyester resin particles [2]. An ink for inkjet recording, comprising an aqueous dispersion of polyester resin particles obtained by the method, and a colorant.

According to the present invention, a method for producing an aqueous dispersion of polyester resin particles, which is excellent in continuous ejection stability while maintaining excellent fixability when used in an inkjet recording ink, and an aqueous dispersion obtained by the method. An ink for inkjet recording containing a liquid can be provided.

[Method for producing aqueous dispersion of polyester resin particles]
The method for producing an aqueous dispersion of polyester resin particles of the present invention includes the following step 1 and step 2.
Step 1: A step of mixing the polyester resin a, the organic solvent, and the organic amine compound to obtain a solution of the polyester resin a neutralized with the organic amine compound Step 2: The neutralized solution obtained in Step 1 A process of adding an aqueous medium to a solution containing the polyester resin a to invert the phase to remove an organic solvent in the system to obtain an aqueous dispersion of polyester resin particles. In the present specification, “printing” means , Is a concept that includes printing and printing in which characters and images are recorded, and “printed matter” is a concept that includes printed matter in which characters and images are recorded and printed matter.

When the aqueous dispersion of polyester resin particles obtained by the production method of the present invention is used in an inkjet recording ink, the above-described excellent effects can be achieved. The reason is not clear, but it is considered as follows.
Organic amine compounds are relatively hydrophobic compared to inorganic basic compounds such as ammonia and metal hydroxides, so polyester resins are neutralized with organic amine compounds and phase inversion emulsification is performed in the presence of an aqueous medium. By performing, it is considered that the organic amine compound forms resin particles in the state of being present near the surface of the polyester resin, and as a result, the acid groups of the polyester resin are present in a relatively large amount near the surface of the resin particles. To be The electrostatic repulsion force of the acid groups existing near the surface of the resin particles improves the dispersion stability of the resin particles and suppresses the aggregation of the resin particles, and thus the continuous ejection stability is also improved. It is thought that you can do it. Further, it is considered that the improvement of the dispersion stability of the resin particles improves the film-forming property and the smoothness of the resin coating film on the surface of the recording medium of the printed matter, and can maintain the excellent fixing property.

In the present invention, the obtained aqueous dispersion of polyester resin particles is obtained by dispersing polyester resin particles in an aqueous medium. The polyester resin particles do not contain a pigment. The aqueous medium is mainly composed of water, but may contain components other than water. Examples of water include deionized water, ion-exchanged water or distilled water. Examples of components other than water include alcohol-based solvents such as methanol, ethanol, isopropanol, butanol; ketone-based solvents such as acetone and methyl ethyl ketone; ether-based solvents such as tetrahydrofuran; and other organic solvents that dissolve in water.
The content of water in the aqueous medium is preferably 80% by mass or more, more preferably 90% by mass or more, and preferably 100% by mass, from the viewpoint of dispersion stability of polyester resin particles and environmental safety. % Or less.

(Process 1)
Step 1 is a step of mixing the polyester resin a, an organic solvent, and an organic amine compound to obtain a solution of the polyester resin a neutralized with the organic amine compound.
The mixing order of the polyester resin a, the organic solvent, and the organic amine compound is not particularly limited, but the polyester resin a is dissolved in an organic solvent to obtain a solution containing the polyester resin a, and then the organic solution is added to the solution. It is preferable to add an amine compound.

<Polyester resin a>
Examples of the polyester resin a include a polyester resin and a modified polyester resin. Examples of the modified polyester resin include urethane-modified polyester resin and epoxy-modified polyester resin. Among them, polyester resin is preferable from the viewpoint of improving continuous ejection stability and fixability.
The polyester resin a may be used alone or in combination of two or more.

The polyester resin a may be a composite resin containing a resin other than the polyester resin as long as the effects of the present invention are not impaired. Examples of the resin other than the polyester resin contained in the composite resin include polystyrene, styrene-propylene copolymer, styrene-butadiene copolymer, styrene-vinyl chloride copolymer, styrene-vinyl acetate copolymer, styrene-malein. Styrene-based resins, epoxy-based resins, and rosin-modified resins that are homopolymers or copolymers containing styrene or styrene substitution products such as acid copolymers, styrene-acrylic acid ester copolymers, styrene-methacrylic acid ester copolymers. Examples thereof include maleic acid resin, polyethylene resin, polypropylene resin, polyurethane resin, silicone resin, phenol resin, and aliphatic or alicyclic hydrocarbon resin. Of these, styrene resins are preferable.
When the composite resin contains a styrene resin in addition to the polyester resin, the composite resin is an addition polymerization product of a raw material monomer containing a polyester resin segment, which is a polycondensation product of an alcohol component and a carboxylic acid component, and a styrene compound. It may include a vinyl-based resin segment and a constitutional unit derived from a bireactive monomer that is bonded to a polyester resin segment and a vinyl-based resin segment via a covalent bond.
The content of the polyester resin in the polyester resin a is preferably 70% by mass or more, more preferably 80% by mass or more, still more preferably 90% by mass or more, even more preferably 95% by mass or more, still more preferably 97% by mass. It is more than 100% by weight, and preferably less than 100% by weight.

[Polyester resin]
The polyester resin preferably contains a structural unit derived from an alcohol component and a structural unit derived from a carboxylic acid component, from the viewpoint of improving continuous ejection stability and fixing property.
In the polyester resin, the total content of the structural unit derived from the alcohol component and the structural unit derived from the carboxylic acid component is preferably 70 mol% or more, more preferably 80 mol% or more, further preferably 90 mol% or more, and , Preferably 100 mol% or less, more preferably 100 mol%.

(Alcohol component)
The alcohol component, which is a raw material monomer of the polyester resin, preferably contains an aromatic ring-containing diol from the viewpoint of improving continuous ejection stability and fixability. As the aromatic ring-containing diol, an alkylene oxide adduct of bisphenol A is preferable. The alkylene oxide adduct of bisphenol A means the entire structure in which an oxyalkylene group is added to 2,2-bis(4-hydroxyphenyl)propane.
The alkylene oxide adduct of bisphenol A is specifically preferably a compound represented by the following general formula (I).

In the general formula (I), OR ¹ and R ² O are both oxyalkylene groups, preferably each independently an oxyalkylene group having 1 to 4 carbon atoms, and more preferably oxyethylene group or oxypropylene group. It is a base.
x and y correspond to the number of moles of alkylene oxide added. Further, from the viewpoint of reactivity with the carboxylic acid component, the average value of the sum of x and y is preferably 2 or more, and preferably 7 or less, more preferably 5 or less, still more preferably 3 or less. ..
Moreover, x OR ¹ and y r ² O may be the same or different, but are preferably the same from the viewpoint of improving fixability. The alkylene oxide adduct of bisphenol A may be used alone or in combination of two or more kinds. The alkylene oxide adduct of bisphenol A is preferably a propylene oxide adduct of bisphenol A and an ethylene oxide adduct of bisphenol A.
The content of the alkylene oxide adduct of bisphenol A in the alcohol component is preferably 50 mol% or more, more preferably 60 mol% or more, still more preferably 70 mol% or more, from the viewpoint of improving continuous dischargeability and fixability. And preferably not more than 100 mol %.

The alcohol component may contain an alcohol component other than the alkylene oxide adduct of bisphenol A.
Other alcohol components include, for example, diols other than alkylene oxide adducts of bisphenol A and trihydric or higher polyhydric alcohols.
Examples of the diol include aromatic ring-containing diols other than aliphatic diols having a main chain carbon number of 2 or more and 12 or less, alicyclic diols, and alkylene oxide adducts of bisphenol A (hereinafter, referred to as "other aromatic ring-containing diols"). (Also called).

Examples of the aliphatic diol include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, 1,8-octanediol, and 1,9-. Examples include nonanediol, 1,10-decanediol, and 1,12-dodecanediol.
The aliphatic diol is preferably an aliphatic diol having a hydroxy group bonded to a secondary carbon atom and having 3 to 6 carbon atoms. Examples of the aliphatic diol having a hydroxy group bonded to a secondary carbon atom and having 3 to 6 carbon atoms include 1,2-propanediol, 1,2-butanediol, 1,3-butanediol, and 2, 3-butanediol, 1,2-pentanediol, 1,4-pentanediol, 2,4-pentanediol, 1,2-hexanediol, 1,5-hexanediol, 2,5-hexanediol, 3,3 -Dimethyl-1,2-butanediol.
The content of the aliphatic diol having a main chain carbon number of 2 or more and 12 or less in the alcohol component is preferably 30 mol% or less, more preferably 20 mol% or less, further preferably 10 mol% or less, and preferably It is 0 mol %.

Examples of the alicyclic diol include cyclohexanediol, hydrogenated bisphenol A, and cyclohexanedimethanol.
The content of the alicyclic diol in the alcohol component is preferably 1 mol% or more, more preferably 2 mol% or more, and preferably 40 mol% or less, more preferably 30 mol% or less.

Other aromatic ring-containing diols include alkylene oxide adducts such as bisphenol F (4,4'-dihydroxydiphenylmethane) and bisphenol S (4,4'-dihydroxydiphenylsulfone).
The content of the other aromatic ring-containing diol in the alcohol component is preferably 30 mol% or less, more preferably 20 mol% or less, still more preferably 10 mol% or less, and preferably 0 mol%. ..
The said alcohol component can be used individually by 1 type or in combination of 2 or more types.

(Carboxylic acid component)
The carboxylic acid component, which is a raw material monomer for the polyester resin, includes carboxylic acids, anhydrides of those acids, and alkyl (having 1 to 3 carbon atoms) esters thereof.
The carboxylic acid component is preferably an aromatic dicarboxylic acid, an aliphatic dicarboxylic acid, an alicyclic dicarboxylic acid, or a polyvalent carboxylic acid having a valence of 3 or more, which improves the reactivity with the alcohol component and improves the continuous ejection stability and fixability. Aromatic dicarboxylic acids and aliphatic dicarboxylic acids are more preferable from the viewpoint of improving
As the aromatic dicarboxylic acid, phthalic acid, isophthalic acid and terephthalic acid are preferable, and terephthalic acid is more preferable.
The content of the aromatic dicarboxylic acid is preferably 40 mol% or more, more preferably 50 mol% in the carboxylic acid component, from the viewpoint of improving the reactivity with the alcohol component and improving the continuous ejection stability and the fixability. The above is more preferably 60 mol% or more, and 100 mol% or less, preferably 95 mol% or less, more preferably 90 mol% or less.

Examples of the aliphatic dicarboxylic acid are substituted with fumaric acid, adipic acid, sebacic acid, maleic acid, azelaic acid, succinic acid, an alkyl group having 1 to 20 carbon atoms or an alkenyl group having 2 to 20 carbon atoms. Examples include succinic acid. Examples of succinic acid substituted with an alkyl group having 1 to 20 carbon atoms or an alkenyl group having 2 to 20 carbon atoms include dodecyl succinic acid, dodecenyl succinic acid, and octenyl succinic acid. Of these, fumaric acid is preferable.
The content of the aliphatic dicarboxylic acid in the carboxylic acid component is preferably 1 mol% or more, more preferably 5 mol% or more, further preferably 10 mol% or more, and preferably 40 mol% or less, more preferably Is 35 mol% or less.
As the alicyclic dicarboxylic acid, for example, cyclohexanedicarboxylic acid, decalin dicarboxylic acid, or tetrahydrophthalic acid may be used.
The content of the alicyclic dicarboxylic acid in the carboxylic acid component is preferably 30 mol% or less, more preferably 20 mol% or less, still more preferably 10 mol% or less, and preferably 0 mol%.
The carboxylic acid components may be used alone or in combination of two or more.

The polyester resin preferably has a cross-linked structure from the viewpoint of improving continuous ejection stability and fixing property.
Here, the crosslinked structure means a structure in which a plurality of branch units are introduced into the polyester chain. The crosslinked structure can be introduced by including a polyhydric alcohol having a valence of 3 or more as the alcohol component or a polycarboxylic acid having a valence of 3 or more as the carboxylic acid component. Among these, it is preferable to include a trivalent or higher polyvalent carboxylic acid as the acid component.
The trivalent or higher polyvalent carboxylic acid is preferably a trivalent or higher polyvalent aromatic carboxylic acid, more preferably a trivalent aromatic carboxylic acid, from the viewpoint of improving continuous ejection stability and fixability.
The carbon number of the trivalent or higher polyvalent aromatic carboxylic acid is preferably 8 or more, more preferably 9 or more, and preferably 16 or less, more preferably 14 or less.
Examples of the trivalent or higher polyvalent aromatic carboxylic acid include trimellitic acid, 2,5,7-naphthalenetricarboxylic acid, and pyromellitic acid. Among them, trimellitic acid or its anhydride is preferable, and trimellitic anhydride is more preferable.
The content of trivalent or higher polycarboxylic acid is preferably 7 mol% or more, more preferably 10 mol% or more, still more preferably 15 mol% in the carboxylic acid component from the viewpoint of improving continuous ejection stability and fixability. It is at least mol%, and preferably at most 45 mol%, more preferably at most 30 mol%, even more preferably at most 25 mol%.
The trivalent or higher carboxylic acid components may be used alone or in combination of two or more.

The equivalent ratio [COOH group/OH group] of the carboxy group (COOH group) of the carboxylic acid component to the hydroxy group (OH group) of the alcohol component in the polyester resin is from the viewpoint of further improving continuous ejection stability and fixing property. It is preferably 0.75 or more, more preferably 0.85 or more, and preferably 1.2 or less, more preferably 1.1 or less.

The polyester resin is obtained by at least polycondensing an alcohol component and a carboxylic acid component. Suitable aspects and suitable contents of the alcohol component and the carboxylic acid component are as described above.
The polyester resin can be produced, for example, by subjecting an alcohol component and a carboxylic acid component to polycondensation at a temperature of 120° C. or higher and 250° C. or lower in an inert gas atmosphere, optionally using an esterification catalyst. ..
Examples of the esterification catalyst include tin compounds such as dibutyltin oxide and tin(II) 2-ethylhexanoate; titanium compounds such as titanium diisopropylate bistriethanolaminate. Further, if necessary, a radical polymerization inhibitor such as 4-tert-butylcatechol can be used.

The acid value of the polyester resin a is preferably 10 mgKOH/g or more, more preferably 13 mgKOH/g or more, from the viewpoint of improving the dispersion stability of the polyester resin particles and improving the continuous ejection stability and the fixability. It is preferably 15 mgKOH/g or more, and preferably 30 mgKOH/g or less, more preferably 25 mgKOH/g or less, still more preferably 23 mgKOH/g or less, still more preferably 20 mgKOH/g or less.
The softening point of the polyester resin a is preferably 125° C. or higher, more preferably 130° C. or higher, still more preferably 135° C. or higher, still more preferably 140° C. or higher, from the viewpoint of improving continuous ejection stability and fixability. Yes, and preferably 160°C or lower, more preferably 150°C or lower.
The glass transition temperature of the polyester resin a is preferably 50° C. or higher, more preferably 60° C. or higher, even more preferably 70° C. or higher, even more preferably 75° C. or higher, from the viewpoint of improving continuous ejection stability and fixability. And preferably 100° C. or lower, more preferably 90° C. or lower, even more preferably 85° C. or lower, even more preferably 80° C. or lower.
The acid value, softening point, and glass transition temperature of the polyester resin a can all be measured by the methods described in the examples, and the types of monomers used, the compounding ratio, the temperature of polycondensation, and the reaction time are adjusted appropriately. By doing so, a desired product can be obtained.

<Organic amine compound>
In step 1, the polyester resin a is neutralized with an organic amine compound from the viewpoint of improving the dispersion stability of the polyester resin particles and improving the continuous ejection stability and the fixing property. The organic amine compound contains at least one primary amino group, secondary amino group, or tertiary amino group.
Examples of the organic amine compound include monoethanolamine, diethanolamine, triethanolamine, n-propanolamine, isopropanolamine, neopentanolamine, 4-amino-1-butanol, 5-amino-4-octanol, 2-amino. Alkanolamines such as 2-methyl-1-propanol and 2-phenyl-2-aminoethanol; N-methylethanolamine, N-ethylethanolamine, Nn-butylethanolamine, N-tert-butylethanolamine, N-Alkylmonoalkanolamines such as N-ethylbutanolamine and 3-(methylamino)-1-propanol; N-methyldiethanolamine, N-ethyldiethanolamine, Nn-butyldiethanolamine, N-tert-butyldiethanolamine, N -N-alkyldialkanolamines such as dodecyldiethanolamine; N-phenyldiethanolamine; N,N-dimethylethanolamine, N,N-diethylethanolamine, N,N-dibutylethanolamine, N,N-dimethylpropanolamine, N , N-dimethylisopropanolamine, 2-(dimethylamino)-2-methyl-1-propanol and other N,N-dialkylmonoalkanolamines; N-(2-aminoethyl)ethanolamine and other aminoalkylalkanolamines; diethylene glycol Amine; 2-amino-1,3-propanediol, 2-amino-2-ethyl-1,3-propanediol, 3-(methylamino)-1,2-propanediol, 3-(dimethylamino)-1 , Aminopropane, such as 2-propanediol; ethylamine, diethylamine, triethylamine, n-propylamine, isopropylamine, diisopropylamine, triisopropylamine, n-butylamine, tert-butylamine, sec-butylamine, 2-ethylhexylamine, triamine. Alkylamines such as -n-octylamine; N-alkylalkanediamines such as N-methyl-1,3-propanediamine; N,N-dialkylalkanediamines such as N,N-dimethyl-1,3-propanediamine; Allylamines; alkylenediamines such as ethylenediamine; aromatic ring-containing alkanolamines such as N-benzylethanolamine; and heterocyclic amines such as piperazine and hydroxyethylpiperazine. Among them, tertiary amines are preferable, and tertiary amines represented by the following general formula (II) are more preferable.

In the formula (II), R ³ , R ⁴ and R ⁵ are a hydrocarbon group having 1 to 8 carbon atoms or a hydrocarbon group containing a hydroxy group and 1 to 8 carbon atoms.
Examples of the hydrocarbon group of R ³ , R ⁴ and R ⁵ include a saturated hydrocarbon group, an unsaturated hydrocarbon group, an alicyclic hydrocarbon group, an aromatic hydrocarbon group, and the like, among which, a straight chain and a branched chain are preferred. A chain or cyclic saturated hydrocarbon group is preferable, and a linear saturated hydrocarbon group is more preferable.
The number of carbon atoms of the hydrocarbon group of R ³ , R ⁴ or R ⁵ is independently 1 or more and 5 or less, and more preferably 1 or more and 3 or less.
R ³ , R ⁴ and R ⁵ are each independently one type selected from an alkyl group having 1 to 3 carbon atoms and a hydroxyalkyl group having 1 to 3 carbon atoms, more preferably a methyl group, It is one kind selected from an ethyl group and a 2-hydroxyethyl group.
As the tertiary amine represented by the general formula (II), at least one of R ³ , R ⁴ and R ⁵ is preferably an alkyl group having 1 to 3 carbon atoms. As a result, the electron density of the nitrogen atom in the tertiary amine is increased, the deprotonation of the acid groups of the polyester resin during phase inversion emulsification is promoted, and the acid groups of the polyester resin particles formed are near the surface. The dispersion stability of the resin particles can be improved.

The total carbon number of the organic amine compound is preferably 2 or more, more preferably 3 or more, still more preferably 4 or more, and preferably 8 or less, more preferably from the viewpoint of improving continuous ejection stability and fixability. Is 7 or less, more preferably 6 or less.

As the organic amine compound, a water-soluble organic amine compound is preferable. “Water-soluble” in the water-soluble organic amine compound means that the solubility in 100 g of water at 25° C. (hereinafter, also simply referred to as “water solubility”) is 5 g/100 g H ₂ O or more. For example, triethylamine is water solubility 9g / 100gH ₂ O at 25 ° C., N, N- dimethylethanolamine is water solubility 95.4g / 100gH ₂ O at 25 ° C., in the N- methyldiethanolamine 25 ° C. The water solubility is 100 g/100 g H ₂ O, and the triethanolamine has a water solubility at 25° C. of 100 g/100 g H ₂ O.

From the viewpoint of improving continuous ejection stability and fixability, the organic amine compound is specifically preferably a trialkanolamine, an N-alkyldialkanolamine, an N,N-dialkylmonoalkanolamine, or a trialkylamine. It is at least one selected, more preferably at least one selected from N-methyldiethanolamine, N,N-dimethylethanolamine, triethanolamine, and triethylamine, and further preferably N-methyldiethanolamine, N,N. -At least one selected from dimethylethanolamine and triethylamine, and more preferably N-methyldiethanolamine.

The amount of the organic amine compound used is preferably 10 mol% or more, more preferably 30 mol% or more, further preferably 50 mol% or more, and more preferably from the viewpoint of improving continuous ejection stability and fixing property. It is 130 mol% or less, more preferably 110 mol% or less, and further preferably 90 mol% or less.
Here, the usage equivalent of the organic amine compound can be determined by the following calculation formula (1). When the use equivalent of the organic amine compound is 100 mol% or less, it is synonymous with the degree of neutralization. When the use equivalent of the organic amine compound exceeds 100 mol% in the following formula, the organic amine compound is equivalent to the polyester resin a. This means that the polyester resin a is in excess of the acid groups, and the degree of neutralization of the polyester resin a at this time is considered to be 100 mol %.
Equivalent amount (mol%) of organic amine compound=[{added mass (g) of organic amine compound/equivalent amount of organic amine compound}/[{acid value of polyester resin a (mgKOH/g)×polyester resin a) Mass (g)}/(56×1,000)]]×100 (1)

To neutralize the polyester resin a in step 1, a basic compound other than the organic amine compound can be used in combination as long as the effect of the present invention is not impaired. Examples of the basic compound include hydroxides of alkali metals, ammonia and the like. The amount of the basic compound other than the organic amine compound used is preferably 20% by mass or less, and more preferably the total amount of the organic amine compound and the basic compound, from the viewpoint of improving continuous ejection stability and fixability. Is 10% by mass or less, more preferably 5% by mass or less, still more preferably 3% by mass or less.

<Organic solvent>
The organic solvent used in step 1 is preferably a water-soluble organic solvent from the viewpoint of phase inversion emulsification of the polyester resin a. The boiling point of the organic solvent at room temperature and atmospheric pressure is preferably 95° C. or lower, more preferably 85° C. from the viewpoint of dissolving the polyester resin a and easily removing the organic solvent after phase inversion in Step 2 described later. From the viewpoint of workability in Step 1, it is preferably 45° C. or higher, more preferably 55° C. or higher.
The organic solvent is preferably an aliphatic alcohol, a ketone, an ether, an ester or the like having 1 to 3 carbon atoms, and more preferably 3 to 6 carbon atoms from the viewpoint of the solubility of the polyester resin a. Ketones are more preferable, and dialkyl ketones having an alkyl group having 1 to 3 carbon atoms such as acetone (boiling point 56° C.) and methyl ethyl ketone (boiling point 80° C.) are more preferable, and methyl ethyl ketone is still more preferable.

When two or more resins are used as the polyester resin a or when the polyester resin a contains a resin other than the polyester resin, a mixture of two or more resins in advance or a polyester resin and another resin is used. A mixture may be used, but these resins may be simultaneously added to an organic solvent and dissolved to obtain a solution containing the polyester resin a.
The operation of dissolving the polyester resin a in an organic solvent and the subsequent addition of the organic amine compound are usually performed at a temperature not higher than the boiling point of the organic solvent.

The mass ratio of the organic solvent to the polyester resin a in the solution obtained in step 1 [organic solvent/polyester resin a] is such that the polyester resin a is dissolved to facilitate phase inversion into an aqueous medium, and the polyester system From the viewpoint of improving the dispersion stability of the resin particles, it is preferably 30/100 or more, more preferably 50/100 or more, still more preferably 70/100 or more, and preferably 500/100 or less, more preferably 300. /100 or less, more preferably 200/100 or less, still more preferably 150/100 or less.

(Process 2)
Step 2 is to add a water-based medium to the solution containing the neutralized polyester resin a obtained in Step 1 for phase inversion, remove the organic solvent in the system, and disperse the polyester resin particles in water. This is a step of obtaining a liquid.
The aqueous medium added in step 2 preferably contains water as a main component. The water in the aqueous medium added in step 2 is the same as the aqueous medium in the aqueous dispersion of the polyester resin particles described above, and may include an organic solvent soluble in water in addition to water. The content of water in the aqueous medium is preferably 80% by mass or more, more preferably 90% by mass or more, from the viewpoint of improving the dispersion stability of the polyester resin particles and the viewpoint of environmental safety, and It is preferably 100% by mass or less.
The temperature at which the aqueous medium is added is preferably 10° C. or higher, more preferably 20° C. or higher, even more preferably 25° C. or higher, and preferably from the viewpoint of improving the dispersion stability of the polyester resin particles. The temperature is 80°C or lower, more preferably 60°C or lower, and further preferably 40°C or lower.

From the viewpoint of improving the dispersion stability of the polyester resin particles, the addition rate of the aqueous medium is preferably 0.5 parts by mass with respect to 100 parts by mass of the polyester resin a used in step 1 until the phase inversion is completed. Parts/min or more, more preferably 1 part by mass/min or more, further preferably 3 parts by mass/min or more, even more preferably 5 parts by mass/min or more, and preferably 100 parts by mass/min or less, It is preferably 50 parts by mass or less, more preferably 20 parts by mass or less, and even more preferably 15 parts by mass or less. After the phase inversion, the addition rate of the aqueous medium after the polyester resin particles are obtained is not limited.
The amount of the aqueous medium added is preferably 50 parts by mass or more, more preferably 100 parts by mass or more, relative to 100 parts by mass of the polyester resin a, from the viewpoint of improving the productivity of the aqueous dispersion of the polyester resin particles. It is more preferably 200 parts by mass or more, and preferably 1,000 parts by mass or less, more preferably 800 parts by mass or less, still more preferably 600 parts by mass or less, still more preferably 400 parts by mass or less.

In step 2, after phase inversion emulsification, the organic solvent in the system is removed from the obtained dispersion liquid of polyester resin particles to obtain an aqueous dispersion liquid of polyester resin particles. The method for removing the organic solvent is not particularly limited, and any method can be used, but it is preferably distilled because it is dissolved in water. The organic solvent in the obtained polyester resin particle aqueous dispersion is preferably substantially removed, but may remain as long as the object of the present invention is not impaired. The amount of residual organic solvent is preferably 0.1% by mass or less, more preferably 0.01% by mass or less.
The obtained aqueous dispersion of polyester resin particles is preferably filtered through a wire mesh or the like to remove coarse particles. Further, after the removal of the organic solvent, water is azeotropically reduced along with the organic solvent, so it is preferable to add water to adjust the solid content concentration.
Further, when the aqueous medium of the aqueous dispersion according to the present invention contains a component other than water, from the viewpoint of adjusting the composition of the aqueous medium of the aqueous dispersion, in step 2, the organic solvent in the system is added after phase inversion. After removal and removal of coarse particles and the like as necessary, the aforementioned organic solvent soluble in water may be added.

The solid content concentration of the aqueous dispersion of polyester resin particles is preferably 5% by mass or more, more preferably 10% by mass or more, further preferably 20% by mass or more, and preferably 50% by mass or less, more preferably Is 45 mass% or less, more preferably 40 mass% or less. The solid content concentration of the aqueous dispersion is measured by the method described in Examples.
The pH of the aqueous dispersion of polyester resin particles is preferably 7.0 or higher, more preferably 7.5 or higher, even more preferably 8.0 or higher, and preferably 9.5 or lower, more preferably 9 or higher. It is 0.0 or less, and more preferably 8.5 or less. The pH of the aqueous dispersion is measured by the method described in Examples.

The volume average particle diameter of the polyester resin particles is preferably 10 nm or more, more preferably 20 nm or more, still more preferably 30 nm or more, still more preferably 40 nm or more, from the viewpoint of improving continuous ejection stability and fixability. And, it is preferably 100 nm or less, more preferably 90 nm or less, further preferably 85 nm or less, still more preferably 80 nm or less. The volume average particle size of the resin particles can be measured by the method described in Examples.

[Inkjet recording ink]
The aqueous dispersion of polyester resin particles obtained by the production method of the present invention is preferably used for an ink for inkjet recording.
The inkjet recording ink preferably contains an aqueous dispersion of polyester resin particles and a colorant, and an aqueous dispersion containing a colorant (hereinafter, also referred to as "colorant aqueous dispersion") is used. It is preferably manufactured by the following step 3.
Step 3: A step of mixing the aqueous dispersion of the polyester resin particles obtained in Step 2 with an aqueous dispersion containing a colorant to obtain an inkjet recording ink. In the mixing in Step 3, various stirring devices are used. Can be used.

<Colorant>
The colorant may be a pigment or a dye.
Examples of colorants include pigments, hydrophobic dyes, water-soluble dyes (acid dyes, reactive dyes, direct dyes, etc.). Among these, pigments and hydrophobic dyes are preferable, and pigments are more preferable.

The pigment used in the present invention may be either an inorganic pigment or an organic pigment. Further, if necessary, they may be used in combination with an extender pigment.
Examples of the inorganic pigment include carbon black, metal oxides, metal sulfides, and metal chlorides. Among these, carbon black is particularly preferable for the black ink. Examples of carbon black include furnace black, thermal lamp black, acetylene black, channel black and the like.
Examples of organic pigments include azo pigments, diazo pigments, phthalocyanine pigments, quinacridone pigments, isoindolinone pigments, dioxazine pigments, perylene pigments, perinone pigments, thioindigo pigments, anthraquinone pigments, and quinophthalone pigments.
Specific examples of preferable organic pigments include C.I. I. Pigment Yellow, C.I. I. Pigment Red, C.I. I. Pigment Violet, C.I. I. Pigment Blue, and C.I. I. Pigment Green, and one or more kinds of each product number selected from the group consisting of Pigment Green. Examples of extender pigments include silica, calcium carbonate, talc and the like.
A so-called self-dispersion pigment can also be used as the pigment. The self-dispersion type pigment is formed by binding one or more kinds of anionic hydrophilic group or cationic hydrophilic group to the surface of the pigment directly or through another atomic group, without using a surfactant or a polymer dispersant. It refers to a pigment that can be dispersed in an aqueous medium. Examples of the anionic hydrophilic group, a carboxyl group (-COOM), a sulfonic acid group (-SO ₃ M) is preferably (wherein, M is a hydrogen atom, an alkali metal, ammonium), cationic hydrophilic group As the above, a quaternary ammonium group is preferable.

The hydrophobic dye used in the present invention means a dye having a solubility in 100 g of water (20° C.), preferably less than 6% by mass. Examples of hydrophobic dyes include oil-soluble dyes and disperse dyes.
Examples of oil-soluble dyes include C.I. I. Solvent Black, C.I. I. Solvent Yellow, C.I. I. Solvent Red, C.I. I. Solvent Violet, C.I. I. Solvent Blue, C.I. I. Solvent Green, and C.I. I. One or more types of product number products selected from Solvent Orange are listed, and they are commercially available from Orient Chemical Co., Ltd., BASF, and the like.
The colorants can be used alone or in combination of two or more kinds and mixed at an arbitrary ratio.

<Polymer dispersant>
The colorant is preferably dispersed in an aqueous medium with a surfactant, a polymer dispersant or the like from the viewpoint of improving continuous ejection stability and fixability, and is a form dispersed with the polymer dispersant. Is more preferable.
Examples of the polymer dispersant include a polymer dispersant having a nonionic group such as a hydroxy group, an amino group, an amide group and an oxyalkylene group; a polymer dispersant having an anionic property such as a carboxy group, a sulfonic acid group and a phosphoric acid group. Agents.

(Water-insoluble polymer b)
The polymer dispersant is preferably a water-insoluble polymer b (hereinafter, also referred to as “polymer b”) from the viewpoint of improving continuous ejection stability and fixability. The polymer b is preferably other than the above polyester resin particles.
Here, "water-insoluble" means that when the polymer b, which has been dried at 105° C. for 2 hours and reaches a constant weight, is dissolved in 100 g of water at 25° C. until it is saturated, the dissolved amount is less than 10 g. The amount of the polymer b dissolved is preferably 5 g or less, more preferably 1 g or less. When the polymer b is an anionic polymer, the amount of dissolution is the amount of dissolution when the anionic groups of the polymer b are 100% neutralized with sodium hydroxide. When the polymer b is a cationic polymer, the amount of dissolution is the amount of dissolution when the cationic groups of the polymer b are 100% neutralized with hydrochloric acid.

Examples of the polymer b include condensation resins such as polyurethane resins and polyester resins; vinyl resins such as acrylic resins, styrene resins, styrene-acrylic resins and acrylic silicone resins. Among them, polyester resin and vinyl resin are preferable, and vinyl resin is more preferable, from the viewpoint of improving continuous ejection stability and fixing property.
When a polyester resin is used as the polymer b, the polyester resin a exemplified in the above polyester resin particles may be used. In the polyester resin used as the polymer b, alcohol components, carboxylic acid components, and other physical properties are preferably in the same ranges as those of the polyester resin particles described above.

The vinyl resin is preferably an ionic monomer (b-1) (hereinafter, also referred to as “(b-1) component”) from the viewpoint of improving the dispersion stability of the colorant and improving the continuous ejection stability and the fixability. And a structural unit derived from the hydrophobic monomer (b-2) (hereinafter, also referred to as “(b-2) component”), and more preferably a nonionic monomer (b-3). (Hereinafter, also referred to as “(b-3) component”). The vinyl resin is a raw material monomer (b) containing a component (b-1), a component (b-2) and, if necessary, a component (b-3) (hereinafter, referred to as “raw material monomer (b)”). (Also referred to as )).

[Ionic monomer (b-1)]
The ionic monomer (b-1) is a monomer having a group capable of becoming an ion under any of acidic, neutral and alkaline conditions (hereinafter, also referred to as “ionic group”), and preferably a monomer or a salt thereof. In either case, the amount of the monomer dissolved in 100 g of ion-exchanged water at 25° C. is 1 g or more, preferably 5 g or more, more preferably 10 g or more.
Examples of the ionic monomer (b-1) include anionic monomers and cationic monomers, and anionic monomers are preferable from the viewpoint of improving continuous ejection stability and fixability.
Examples of the anionic monomer include a carboxylic acid monomer, a sulfonic acid monomer, and a phosphoric acid monomer. Of these, carboxylic acid monomers are preferable.
Examples of the carboxylic acid monomer include acrylic acid, methacrylic acid, maleic acid, fumaric acid and 2-methacryloyloxymethylsuccinic acid. Of these, at least one selected from acrylic acid and methacrylic acid is more preferable.

[Hydrophobic monomer (b-2)]
The hydrophobic monomer (b-2) has a carbon number of 1 or more and 22 or less, more preferably a carbon number of 6 or more and 18 or less, from the viewpoint of improving the dispersion stability of the colorant and improving the continuous ejection stability and the fixability. Alkyl (meth)acrylates having an alkyl group of styrene; styrene-based monomers such as styrene, 2-methylstyrene, divinylbenzene; aromatic group-containing (meth)acrylates such as benzyl (meth)acrylate and phenoxyethyl (meth)acrylate. Can be mentioned. In the present specification, “(meth)acrylate” means “one or more selected from acrylate and methacrylate”. The same applies to the following. The molecular weight of the styrene-based monomer or the aromatic group-containing (meth)acrylate is preferably less than 500.
The hydrophobic monomer (b-2) is preferably styrene or benzyl (meth)acrylate.

As the hydrophobic monomer (b-2), a macromonomer may be used from the viewpoint of improving the dispersion stability of the colorant and improving the continuous ejection stability and the fixability.
The macromonomer is a compound having a polymerizable functional group at one end and having a number average molecular weight of 500 or more and 100,000 or less, preferably a number average molecular weight of 1,000 or more and 10,000 or less. The number average molecular weight is a value measured by gel permeation chromatography using chloroform containing 1 mmol/L of dodecyldimethylamine as a solvent and polystyrene as a standard substance.
The polymerizable functional group present at one end is preferably an acryloyloxy group or a methacryloyloxy group, more preferably a methacryloyloxy group.
The macromonomer is preferably one or more selected from aromatic group-containing monomer-based macromers and silicone-based macromers, and more preferably aromatic group-containing monomer-based macromers.
Examples of the aromatic group-containing monomer that constitutes the aromatic group-containing monomer-based macromonomer include the above-mentioned styrene-based monomers and aromatic group-containing (meth)acrylates, styrene and benzyl (meth)acrylate are preferable, and styrene is more preferable. preferable.
Specific examples of the styrene-based macromonomer include AS-6(S), AN-6(S), HS-6(S) (these are trade names of Toagosei Co., Ltd.).
Examples of silicone macromonomers include organopolysiloxanes having a polymerizable functional group at one end.

[Nonionic monomer (b-3)]
The nonionic monomer (b-3) does not have an ionic group, and preferably has a solubility of 10 g or more in 100 g of ion-exchanged water at 25°C.
The nonionic monomer (b-3) is preferably a monomer having at least one of a hydroxyl group and a polyalkyleneoxy group. Specific examples thereof include hydroxyalkyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate and 3-hydroxypropyl (meth)acrylate; polypropylene glycol (n=2 to 30, where n is an average addition mole of an oxyalkylene group). The same applies hereinafter) Polyalkylene glycol mono(meth)acrylate such as mono(meth)acrylate, polyethylene glycol (n=2-30) mono(meth)acrylate; methoxypolyethylene glycol (n=1-30) (meth ) Alkoxy polyalkylene glycol (meth)acrylates such as acrylates; phenoxy (ethylene glycol-propylene glycol copolymerization) (n=1 to 30, ethylene glycol therein: n=1 to 29) (meth)acrylate and the like. .. Among these, polyalkylene glycol mono(meth)acrylate is preferable, and polypropylene glycol (n=2 to 30) mono(meth)acrylate and polyethylene glycol (n=2 to 30) mono(meth)acrylate are more preferable.
Specific examples of the commercially available nonionic monomer (b-3) include NK ester M-20G, 40G, 90G and 230G manufactured by Shin-Nakamura Chemical Co., Ltd., manufactured by NOF CORPORATION. Bremmer PE-90, 200, 350, PME-100, 200, 400, etc., PP-500, 800, 1000, AP-150, 400, 550, 50PEP-300, 50POEP- 800B, 43PAPE-600B, etc. are mentioned.
The components (b-1) to (b-3) can be used alone or in combination of two or more.

From the viewpoint of improving the dispersion stability of the colorant and improving the continuous ejection stability and the fixability, the polymer b is a structural unit derived from a carboxylic acid monomer as the ionic monomer (b-1) and a hydrophobic monomer (b). -2) is preferably a vinyl-based resin containing a structural unit derived from at least one monomer selected from styrene-based monomers and aromatic group-containing (meth)acrylates, and derived from at least one monomer selected from acrylic acid and methacrylic acid. A vinyl-based resin containing the structural unit of 1 and a structural unit derived from at least one monomer selected from styrene and benzyl (meth)acrylate is more preferable.

(Content of each component of the water-insoluble polymer b)
Content of the ionic monomer (b-1), the hydrophobic monomer (b-2), and the nonionic monomer (b-3) in the raw material monomer (b) during the production of the polymer b (as an unneutralized amount) The content is the same hereinafter), that is, the content of the constituent units derived from the components (b-1) to (b-3) in the polymer b improves the dispersion stability of the colorant, and improves the continuous ejection stability and fixing. From the viewpoint of improving the property, it is as follows.
The content of the component (b-1) is preferably 10% by mass or more, more preferably 13% by mass or more, further preferably 15% by mass or more, and preferably 30% by mass or less, more preferably 27% by mass. % Or less, more preferably 25% by mass or less.
The content of the component (b-2) is preferably 40% by mass or more, more preferably 45% by mass or more, further preferably 48% by mass or more, and preferably 85% by mass or less, more preferably 80% by mass. % Or less, more preferably 75% by mass or less.
The content of the component (b-3) is preferably 0.1% by mass or more, more preferably 10% by mass or more, further preferably 20% by mass or more, and preferably 40% by mass or less, more preferably It is 37 mass% or less, more preferably 35 mass% or less.
The mass ratio of the component (b-2) to the component (b-1) [(b-2) component/(b-1) component] is preferably 0.5 or more, more preferably 1.0 or more, still more preferably Is 1.5 or more, more preferably 2.0 or more, and preferably 5.0 or less, more preferably 4.0 or less, still more preferably 3.5 or less.

The polymer b is produced by copolymerizing the raw material monomer (b) by a known polymerization method. As a preferable example of the polymerization method, a solution polymerization method in which the raw material monomer (b) is heated in a solvent together with a polymerization initiator, a polymerization chain transfer agent or the like to carry out polymerization is mentioned.
After the completion of the polymerization reaction, the produced polymer may be isolated and purified by a known method such as reprecipitation from the reaction solution or evaporation of the solvent.
There is no limitation on the chain mode of the polymerized monomers in the polymer b, and any polymerization mode such as random, block or graft may be used.

From the viewpoint of improving the dispersion stability of the colorant, the acid value of the polymer b is preferably 80 mgKOH/g or more, more preferably 100 mgKOH/g or more, further preferably 120 mgKOH/g or more, and preferably 300 mgKOH/g. g or less, more preferably 200 mgKOH/g or less, still more preferably 150 mgKOH/g or less. The acid value (mgKOH/g) of the polymer b can be calculated from the mass ratio of the constituent monomers.

The number average molecular weight of the polymer b is preferably 3,000 or more, more preferably 5,000 or more, still more preferably 10,000 or more, and preferably 100 from the viewpoint of improving the dispersion stability of the colorant. 2,000 or less, more preferably 50,000 or less, still more preferably 30,000 or less. The number average molecular weight of the polymer b can be measured by the method described in Examples.

<Crosslinking agent>
The water-insoluble polymer b (polymer b) preferably has a cross-linking structure, more preferably a polymer cross-linked with a cross-linking agent or a self-cross-linking polymer without using the cross-linking agent, and further preferably cross-linking. It is a polymer cross-linked with an agent. As a result, the crosslinked polymer b is strongly adsorbed or fixed on the surface of the colorant, and swelling of the polymer b in the ink is also suppressed, so that continuous ejection stability and fixability are considered to be improved.
The cross-linking agent is preferably a compound having a cross-linkable functional group that reacts with the reactive functional group contained in the polymer b. The number of crosslinkable functional groups contained in the crosslinker is 2 or more per molecule, and preferably 6 per molecule, from the viewpoint of efficiently promoting the crosslinking reaction and improving the continuous ejection stability and the fixability. From the viewpoint of market availability, it is preferably 4 or less, more preferably 3 or less.

When the polymer b contains, for example, a carboxy group as an ionic group, the reactive functional group of the crosslinking agent is preferably one or more selected from an epoxy group, an oxazoline group, and an isocyanate group.
Specific examples of the crosslinking agent include a compound having two or more epoxy groups in the molecule, a compound having two or more oxazoline groups in the molecule, and a compound having two or more isocyanate groups in the molecule. Among them, a compound having two or more epoxy groups in the molecule is preferable from the viewpoint of improving continuous ejection stability and fixability.

Examples of the compound having two or more epoxy groups in the molecule include polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, glycerol polyglycidyl ether, polyglycerol polyglycidyl ether, trimethylolpropane polyglycidyl ether, cyclohexane dimethanol dimethanol. Polyglycidyl ethers such as glycidyl ether, sorbitol polyglycidyl ether, pentaerythritol polyglycidyl ether, resorcinol diglycidyl ether, neopentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, hydrogenated bisphenol A type diglycidyl ether Can be mentioned. Among these, 1,6-hexanediol diglycidyl ether is preferable.

The amount of the cross-linking agent used is a mass ratio of the cross-linking agent to the polymer b [cross-linking agent/polymer b], preferably 0. It is 1/100 to 50/100, more preferably 1/100 to 40/100, still more preferably 3/100 to 30/100, still more preferably 4/100 to 25/100.

The crosslinking rate (mol %) of the cross-linked polymer b is preferably 5 mol% or more, more preferably 10 mol% or more, further preferably 15 mol% or more, and preferably 80 mol% or less, more preferably Is 60 mol% or less, more preferably 50 mol% or less, still more preferably 40 mol% or less. The crosslinking rate is obtained from the following calculation formula (2).
Crosslinking rate (mol %)=[number of mole equivalents of crosslinkable functional group of crosslinking agent/number of mole equivalents of reactive functional group of polymer b]×100 (2)
The conditions for the crosslinking reaction are preferably a reaction temperature of 60° C. or higher and 95° C. or lower and a reaction time of 0.5 hour or longer and 7 hours or shorter.

The existing form of the polymer b in the ink may be in the state of being adsorbed on the colorant, in the state of containing the colorant, or in the form of not adsorbing the colorant. Among these, from the viewpoint of improving the dispersion stability of the colorant and improving the continuous ejection stability and the fixability, the state in which the colorant is adsorbed and the state in which the colorant is contained are preferable.
That is, the colorant is preferably in the form of particles contained in the polymer b (hereinafter, also referred to as “particles of the polymer b containing the colorant” or “colorant-containing polymer particles”). Here, the colorant-containing polymer particles include the form of particles in which the polymer b is adsorbed on at least a part of the colorant, the form of particles in which the polymer b contains the colorant, and the like.
The colorant constituting the colorant-containing polymer particles is preferably at least one selected from pigments and hydrophobic dyes from the viewpoint of improving the dispersion stability of the colorant, and improving the continuous ejection stability and fixability. , And more preferably a pigment. When a pigment is used as the colorant, the colorant-containing polymer particles are pigment particles in which the pigment is contained in the polymer b, that is, particles of the polymer b containing the pigment.

[Production of colorant aqueous dispersion]
The aqueous dispersion containing the colorant (colorant aqueous dispersion) is preferably a dispersion obtained by mechanically dispersing the colorant with the above water-insoluble polymer b (polymer b). For example, after a dispersion treatment of a colorant mixture containing a polymer b, an organic solvent, a colorant, water, and optionally a neutralizing agent, a surfactant, etc., to obtain a dispersion liquid of colorant-containing polymer particles, It can be obtained by removing the organic solvent in the system from the dispersion.
The organic solvent for dissolving the polymer b is not limited, but aliphatic alcohols having 1 to 3 carbon atoms, ketones, ethers, esters and the like are preferable, and wettability to a colorant, solubility of the polymer b, and From the viewpoint of improving the adsorptivity of the polymer b to the colorant, a ketone having 4 to 8 carbon atoms is more preferable, methyl ethyl ketone and methyl isobutyl ketone are still more preferable, and methyl ethyl ketone is still more preferable.
When the polymer b is synthesized by the solution polymerization method, the solvent used in the polymerization may be used as it is.

When the polymer b is an anionic polymer, a neutralizing agent may be used to neutralize the anionic groups in the polymer b. When a neutralizing agent is used, it is preferably neutralized so that the pH is 7 or more and 11 or less.
Examples of the neutralizing agent include alkali metal hydroxides, ammonia, organic amine compounds and the like. Further, the polymer b may be neutralized in advance.

The method of dispersing the colorant mixture is not particularly limited, but it is preferable that the average particle size of the colorant-containing polymer particles is controlled to a desired particle size by using a known kneader, disperser or the like. The organic solvent is removed from the obtained dispersion-treated product by a known method to obtain a colorant aqueous dispersion. When the polymer b is a polymer obtained by crosslinking with a crosslinking agent, it is preferable to add a crosslinking agent to the obtained colorant aqueous dispersion to crosslink the colorant-containing polymer particles.

The solid content concentration of the colorant aqueous dispersion is preferably 10% by mass or more, more preferably 15% by mass or more, from the viewpoint of improving the dispersion stability of the colorant and facilitating the preparation of the ink. And it is preferably 30 mass% or less, more preferably 25 mass% or less. The solid content concentration of the colorant aqueous dispersion is measured by the method described in Examples.
The volume average particle diameter of the colorant-containing polymer particles in the colorant aqueous dispersion is preferably 40 nm or more, more preferably 60 nm or more from the viewpoint of reducing coarse particles and improving the continuous ejection stability and fixability. , More preferably 75 nm or more, still more preferably 100 nm or more, and preferably 300 nm or less, more preferably 200 nm or less, still more preferably 150 nm or less. The volume average particle diameter of the colorant-containing polymer particles in the colorant aqueous dispersion is measured by the method described in Examples.

The colorant-containing polymer particles in the ink preferably do not cause swelling or shrinkage of the particles or aggregation between the particles, and the volume average particle diameter of the colorant-containing polymer particles in the ink is the same as that in the colorant aqueous dispersion. More preferably, it is the same as the average particle size of. The preferable volume average particle diameter of the colorant-containing polymer particles in the ink is the same as the preferable volume average particle diameter of the colorant aqueous dispersion. The volume average particle diameter of the colorant-containing polymer particles in the ink is also measured by the method described in Examples.

<Water-soluble organic solvent>
The ink of the present invention preferably further contains a water-soluble organic solvent (hereinafter referred to as “water-soluble organic solvent”) from the viewpoint of improving continuous ejection stability and fixing property. Examples of the water-soluble organic solvent include polyhydric alcohols, polyhydric alcohol alkyl ethers, nitrogen-containing heterocyclic compounds, amides, amines, and sulfur-containing compounds. Of these, at least one selected from polyhydric alcohols, polyhydric alcohol monoalkyl ethers and nitrogen-containing heterocyclic compounds is preferable. The total content of one or more selected from polyhydric alcohols, polyhydric alcohol alkyl ethers and nitrogen-containing heterocyclic compounds in the water-soluble organic solvent is preferably 80% by mass or more, more preferably 90% by mass or more. , And preferably 100% by mass or less.

The water-soluble organic solvent is more preferably a polyhydric alcohol from the viewpoint of improving continuous ejection stability and fixability.
Examples of the polyhydric alcohol include ethylene glycol (boiling point 197° C.), diethylene glycol (boiling point 244° C.), polyethylene glycol, propylene glycol (boiling point 188° C.), dipropylene glycol (boiling point 232° C.), polypropylene glycol, 1,3- Propanediol (boiling point 210°C), 1,3-butanediol (boiling point 208°C), 1,4-butanediol (boiling point 230°C), 3-methyl-1,3-butanediol (boiling point 203°C), 1, 5-pentanediol (boiling point 242°C), 1,6-hexanediol (boiling point 250°C), 2-methyl-2,4-pentanediol (boiling point 196°C), 1,2,6-hexanetriol (boiling point 178°C) ), 1,2,4-butanetriol (boiling point 190° C.), 1,2,3-butanetriol (boiling point 175° C.), petriol (boiling point 216° C.) and the like. In addition, a polyhydric alcohol having a boiling point of more than 250° C., such as triethylene glycol (boiling point 285° C.), tripropylene glycol (boiling point 273° C.), glycerin (boiling point 290° C.), a polyhydric alcohol having a boiling point of less than 250° C., preferably Can also be used in combination with a polyhydric alcohol having a boiling point of less than 230°C. Among these, from the viewpoint of improving continuous ejection stability, at least one selected from ethylene glycol, diethylene glycol, propylene glycol and polypropylene glycol is preferable, and at least one selected from diethylene glycol and polypropylene glycol is more preferable. ..

Polypropylene glycol is formally a condensation polymer of propylene glycol, is substantially a polymer of propylene oxide, and has a distribution composed of a plurality of components having different degrees of polymerization. It is considered that polypropylene glycol imparts an appropriate viscosity to the ink, alleviates the association force of the aggregated deposits of the ink generated near the nozzle holes of the print head, and improves the continuous ejection stability.
The degree of polymerization of polypropylene glycol is preferably 3 or more, more preferably 4 or more, still more preferably 5 or more, still more preferably 6 or more from the viewpoint of imparting an appropriate viscosity to the ink and improving the continuous ejection stability. And preferably 30 or less, more preferably 25 or less, still more preferably 20 or less, still more preferably 15 or less.
The average molecular weight of polypropylene glycol is preferably 300 or more, more preferably 400 or more, and preferably 1,000 or less, more preferably from the viewpoint of imparting appropriate viscosity to the ink and improving continuous ejection stability. Is 800 or less.

The ink of the present invention may further contain various additives such as a surfactant, a wetting agent, a penetrating agent, a viscosity modifier, a defoaming agent, a mildew-proofing agent, an anticorrosive agent, an antioxidant and an ultraviolet absorber, if necessary. Can be included.

When the ink of the present invention further contains a water-soluble organic solvent, a surfactant, and the above-mentioned various additives, at least one of these may be further mixed in any of Steps 1 to 3. Well, it is preferable to mix in step 3.
The content of each component of the ink of the present invention and the physical properties of the ink are as follows.

The content of the aqueous dispersion of polyester resin particles in the ink of the present invention is preferably 0.1% by mass or more, more preferably 0.1% by mass as a solid content from the viewpoint of improving continuous ejection stability and fixability. 3 mass% or more, more preferably 0.5 mass% or more, and preferably 10 mass% or less, more preferably 7 mass% or less, further preferably 3 mass% or less, even more preferably 1 mass% or less. Is. From the viewpoint of adjusting the ink composition, the aqueous medium may be removed from the aqueous dispersion of polyester resin particles in advance to adjust the solid content concentration, and then blended into the ink.

The content of the colorant in the ink of the present invention is preferably 1% by mass or more, more preferably 2% by mass or more, further preferably 3% by mass or more, from the viewpoint of printing density, and when the solvent volatilizes. From the viewpoint of lowering the ink viscosity and improving the continuous ejection stability and the fixing property, it is preferably 15% by mass or less, more preferably 10% by mass or less, further preferably 7% by mass or less, still more preferably 5% by mass or less. Is.

The mass ratio [colorant/polyester resin particles] of the colorant and the polyester resin particles in the ink of the present invention is preferably 60/40 or more, from the viewpoint of improving print density, continuous ejection stability and fixability. It is preferably 70/30 or more, more preferably 80/20 or more, and preferably 95/5 or less, more preferably 90/10 or less, further preferably 85/15 or less.

The total content of the colorant and the polymer b in the ink of the present invention is preferably 2% by mass or more, more preferably 3% by mass or more, further preferably 4% by mass or more, from the viewpoint of printing density, and From the viewpoint of improving continuous ejection stability and fixability, it is preferably 15% by mass or less, more preferably 10% by mass or less, still more preferably 7% by mass or less, still more preferably 5% by mass or less.

The mass ratio of the colorant to the polymer b in the ink of the present invention [colorant/polymer b] is preferably 30/70 or more, more preferably 40/60 or more, from the viewpoint of improving continuous ejection stability and fixability. It is more preferably 50/50 or more, still more preferably 60/40 or more, and preferably 90/10 or less, more preferably 85/15 or less, still more preferably 80/20 or less.

The content of the water-soluble organic solvent in the ink of the present invention is preferably 5% by mass or more, more preferably 10% by mass or more, and further preferably 20% by mass or more, from the viewpoint of improving continuous ejection stability and fixability. And preferably 47% by mass or less, more preferably 43% by mass or less, still more preferably 40% by mass or less.

The content of water in the ink of the present invention is preferably 40% by mass or more, more preferably 50% by mass or more, and further preferably from the viewpoint of improving continuous ejection stability and fixing property, and from the viewpoint of reducing environmental load. Is 55% by mass or more, and preferably 80% by mass or less, more preferably 70% by mass or less, and further preferably 65% by mass or less.

The pH of the ink is preferably 5.5 or more, more preferably 6.0 or more, still more preferably 6.5 or more, from the viewpoint of improving continuous ejection stability, and from the viewpoint of member resistance and skin irritation. Therefore, it is preferably 11.0 or less, more preferably 10.0 or less, still more preferably 9.5 or less. The pH of the ink is measured by the method described in the examples.
The viscosity of the ink at 20° C. is preferably 1.0 mPa·s or more, more preferably 1.5 mPa·s or more, further preferably 2.0 mPa·s or more, from the viewpoint of continuous ejection stability, and From the same viewpoint, it is preferably 12 mPa·s or less, more preferably 8.0 mPa·s or less, still more preferably 4.0 mPa·s or less. The viscosity of the ink is measured by the method described in the examples using an E-type viscometer.

[Inkjet recording method]
The ink of the present invention can be loaded in a known inkjet recording device and ejected as an ink droplet onto a recording medium to record an image or the like.
The inkjet recording device includes a thermal type and a piezo type, but it is more preferable to use it as a piezo type inkjet recording ink.
Examples of the recording medium used include plain paper, which is a highly water-absorbent printing medium, coated paper, which is a low-water-absorbent printing medium, and resin film. Among them, a low water-absorbent printing medium is preferable from the viewpoint of fixability.
The water absorption amount of the low water-absorptive printing medium at a contact time of 100 msec with pure water is preferably 8 g/m ² or less, more preferably 6 g/m ² or less, and preferably from the viewpoint of fixability and print image quality. Is 1 g/m ² or more, more preferably 2 g/m ² or more. The water absorption amount is measured by the method described in Examples using an automatic scanning liquid absorption meter.

Examples of the coated paper include general-purpose glossy paper and multicolor foam gloss paper. Examples of commonly available coated papers include "OK Top Coat Plus" (manufactured by Oji Paper Co., Ltd.), multicolor foam gloss paper (manufactured by Oji Paper Co., Ltd.); UPM Finesse Gloss, UPM Finesse Matt (above, UPM). TerraPress Silk, LumiArt (above, manufactured by Stora Enso).
The resin film is preferably at least one selected from polyester film, polyvinyl chloride film, polypropylene film, and polyethylene film. The resin film may use a corona-treated base material.
Examples of commonly available resin films include Lumirror T60 (Toray Industries, Inc., polyester), PVC80BP (Lintec Inc., vinyl chloride), DGS-210WH (Roland DG Inc., vinyl chloride), transparent PVC RE-137 (Vinyl chloride manufactured by Mimaki Engineering Co., Ltd.), Kainus KEE70CA (polyethylene manufactured by Lintec Co., Ltd.), YUPO SG90 PAT1 (polypropylene manufactured by Lintec Co., Ltd.), FOR, FOA (all manufactured by Futamura Chemical Co., Ltd., Polypropylene), Bonil RX (manufactured by Kojin Film & Chemicals Co., Ltd., nylon), and emblem ONBC (Unitika Co., Ltd., nylon).

The ink jet recording method may include a step of ejecting ink droplets onto a recording medium by an ink jet recording method to print, and then drying the ink droplets landed on the recording medium. In the drying step, the surface temperature of the recording medium is preferably 25° C. or higher, more preferably 30° C. or higher, even more preferably 50° C. or higher, from the viewpoint of improving print image quality, and suppressing deformation of the recording medium by heat. From the viewpoint of energy reduction, the temperature is preferably 100°C or lower, more preferably 85°C or lower, and further preferably 70°C or lower.

In the following examples and the like, "parts" and "%" are "parts by mass" and "mass %" unless otherwise specified. Each physical property was measured by the following methods.

(1) except that the solvent for measuring the acid value of the polyester resin a is changed from the mixed solvent of ethanol and ether to the mixed solvent of acetone and toluene (acetone:toluene=1:1 (volume ratio)) It was measured according to the neutralization titration method described in JIS K0070-1992.

(2) Using a softening point flow tester "CFT-500D" (manufactured by Shimadzu Corp.) of polyester resin a while heating 1 g of a sample at a heating rate of 6°C/min, a load of 1.96 MPa was applied by a plunger. And was extruded from a nozzle having a diameter of 1 mm and a length of 1 mm. The amount of plunger drop of the flow tester was plotted against the temperature, and the temperature at which half the sample flowed out was taken as the softening point.

(3) Glass transition temperature of polyester resin a Using a differential scanning calorimeter "Q-100" (manufactured by TA Instruments Japan Co., Ltd.), 0.01 to 0.02 g of a sample is weighed in an aluminum pan, After raising the temperature to 200° C., it was cooled from 200° C. to 0° C. at a temperature decrease rate of 10° C./min to prepare a measurement sample. After that, the temperature is raised at a heating rate of 10° C./min, and the temperature at the intersection of the extension line of the baseline below the maximum peak temperature of the endotherm and the tangent line showing the maximum slope from the rising portion of the peak to the apex of the peak is glass transition. Temperature.

(4) Volume Average Particle Diameter of Polyester Resin Particles and Colorant-Containing Polymer Particles The volume average particle diameter was measured using the following measuring device under the following measurement conditions.
Measuring device: Zeta potential/particle size measuring system "ELS-8000" (manufactured by Otsuka Electronics Co., Ltd.)
Measurement conditions: cumulant analysis method. The dispersion liquid diluted with water so that the concentration of the particles to be measured is about 5×10 ⁻³ % was put in the measurement cell, the temperature was 25° C., the number of integration was 100 times, and the refractive index of the dispersion solvent was water refraction. The rate (1.333) was entered.

(5) Solid Content Concentration of Aqueous Dispersion of Polyester Resin Particles and Aqueous Dispersion of Colorant Using an infrared moisture meter (Kett Scientific Research Co., Ltd., trade name: FD-230), 5 g of a sample was dried at a temperature of 150. The sample was dried under conditions of ℃ and measurement mode 96 (monitoring time 2.5 minutes/variation width 0.05%), and the water content (%) of the aqueous dispersion was measured. The solid content concentration was calculated according to the following formula.
Solid content concentration (%) = 100-water content (%)

(6) pH of aqueous dispersion of polyester resin particles
It measured at 25 degreeC using the pH meter "HM-20P" (made by Toa DKK Co., Ltd.).

(7) Measurement of number average molecular weight of water-insoluble polymer b Gel was prepared using N,N-dimethylformamide in which phosphoric acid and lithium bromide were dissolved to have concentrations of 60 mmol/L and 50 mmol/L, respectively, as an eluent. Permeation chromatography method [Tosoh Corporation GPC device (HLC-8320GPC), Tosoh Corporation column (TSK-GEL SuperAWM-H, TSKgel SuperAW 3000, TSKgel guardcolumn Super AW-H), flow rate: 1 mL/min], standard Monodisperse polystyrene kit having a known molecular weight as a substance [PStQuick B (F-550, F-80, F-10, F-1, A-1000), PStQuick C (F-288, F-40, F-4, A-5000, A-500), manufactured by Tosoh Corporation].
The measurement sample was prepared by mixing 0.1 g of the polymer b in a glass vial with 10 mL of the eluent, stirring the mixture with a magnetic stirrer at 25° C. for 10 hours, and using a syringe filter (DISMIC-13HP PTFE 0.2 μm, manufactured by Advantech Co., Ltd.). What was filtered with.

(8) Viscosity and pH of inkjet recording ink
The viscosity of the ink at 20° C. was measured using an E-type viscometer (manufactured by Toki Sangyo Co., Ltd., model number: TV-25, standard cone rotor 1°34′×R24, rotation speed 50 rpm).
The pH of the ink was measured using a desktop pH meter "F-71" (manufactured by HORIBA, Ltd.) using a pH electrode "6337-10D" (manufactured by HORIBA, Ltd.).

(9) Water absorption amount of recording medium at contact time of 100 msec between recording medium and pure water Using an automatic scanning liquid absorption meter “KM500win” (manufactured by Kumagai Riki Kogyo Co., Ltd.), conditions of 23° C. and relative humidity of 50% The amount of transition of pure water at a contact time of 100 msec was measured under the conditions below, and the water absorption amount was 100 msec. The measurement conditions are shown below.
"Spiral Method"
Contact Time (sec): 0.010-1.0
Pitch (mm): 7
Length Per Sampling(degree):86.29
Start Radius (mm): 20
End Radius (mm):60
Min Contact Time (msec): 10
Max Contact Time (msec): 1,000
Sampling Pattern:50
Number of Sampling Points:19
"Square Head"
Slit Span (mm): 1
Slit Width(mm):5

[Preparation of aqueous dispersion of pigment-containing polymer particles]
Preparation example 1
(1) Pre-dispersion step As the water-insoluble polymer b, a methacrylic acid/benzyl acrylate/styrene macromonomer (manufactured by Toagosei Co., Ltd., trade name: AS-6S)/polyethylene glycol (4) monomethacrylate copolymer (monomer Mass ratio (methacrylic acid/benzyl acrylate/styrene-based macromonomer/polyethylene glycol (4) monomethacrylate)=20/40/10/30, acid value: 130 mgKOH/g, number average molecular weight: 11,218) of 36.8 % Methyl ethyl ketone (hereinafter, also referred to as “MEK”) solution containing 5%, ion-exchanged water 1466 g, 5N sodium hydroxide aqueous solution 94.4 g (polymer b neutralization degree: 80 mol %), and MEK188.3 g were added to emulsify. A liquid was obtained.
To this emulsion, 500 g of a cyan pigment (CI Pigment Blue 15:3, copper phthalocyanine, manufactured by DIC Corporation, trade name: TGR-SD) was added as a colorant, and the mixture was mixed with a disper blade at 15° C. for 1 hour. Preliminary dispersion (solid content concentration: 20%) was obtained by mixing for a period of time.
(2) Main Dispersion Step After adding 69 g of MEK and 945 g of ion-exchanged water to the preliminary dispersion obtained in (1) above, using a microfluidizer (manufactured by Microfluidics, high-pressure homogenizer, trade name) The pigment dispersion liquid was obtained by performing a dispersion treatment in a continuous system of 15 passes at a pressure of 150 MPa.
(3) Organic solvent removal step MEK is removed from the pigment dispersion obtained in the above (2) using a hot water heating medium under reduced pressure so that the solid content of the resulting pigment water dispersion becomes 20%. To remove water (residual organic solvent amount: 0.01%), filter with a 2.5 μm filter (manufactured by Roki Techno Co., Ltd., trade name: 20L-MPX-025XS, outer diameter: 9.1 cm), and coarse By removing the particles, an aqueous pigment dispersion having a solid content concentration of 20% was obtained.
(4) Crosslinking Step: 0.811 g of a crosslinking agent (trade name: Denacol EX212L, 1,6-hexanediol diglycidyl ether, manufactured by Nagase Chemtex Co., Ltd.) with respect to 200 g of the pigment aqueous dispersion obtained in (3) above. Was added and stirred at 70° C. for 90 minutes to crosslink the polymer b (crosslinking ratio: 20 mol %) to obtain an aqueous dispersion P-1 of pigment-containing polymer particles (solid content concentration 20%, volume average particle diameter 90 nm). Obtained.

[Manufacture of polyester resin]
Production Examples 1 and 2
A 10 L four-necked flask equipped with a thermometer, a stirring rod made of stainless steel, a downflow condenser having a dehydration tube, and a nitrogen introduction tube was charged with a raw material monomer other than trimellitic anhydride shown in Table 1 and 2-ethyl as a catalyst. Tin (II) hexanoate was added, and the temperature was raised to 235° C. with stirring under a nitrogen atmosphere and maintained for 5 hours, after which the pressure in the flask was further reduced and maintained at 8.3 kPa for 1 hour. Then, after cooling to 200° C. and returning to atmospheric pressure, trimellitic anhydride was added, the temperature was raised to 220° C. and maintained for 1 hour, after which the pressure inside the flask was further lowered and softened at 8.3 kPa. The reaction was carried out until the points reached the temperatures shown in Table 1 to obtain polyester resins a1 and a2. Table 1 shows the physical properties of the obtained resins a1 and a2.

Production Example 3
A 10 L four-necked flask equipped with a thermometer, a stainless steel stirring rod, a downflow condenser having a dehydration tube, and a nitrogen introducing tube was used as a raw material monomer other than fumaric acid shown in Table 1, and tin 2-ethylhexanoate as a catalyst ( II) was added, the temperature was raised to 235° C. with stirring under a nitrogen atmosphere, and the temperature was maintained for 8 hours. Then, the pressure in the flask was further reduced and maintained at 8.3 kPa for 1 hour. Then, after cooling to 200° C. and returning to atmospheric pressure, fumaric acid and 4-tert-butylcatechol were added, and after maintaining at a temperature of 210° C. for 4 hours, the pressure inside the flask was further lowered to 8.3 kPa. The reaction was carried out until the softening point reached the temperature shown in Table 1 to obtain polyester resin a3. Table 1 shows the physical properties of the obtained resin a3.

Production Example 4
As a raw material monomer other than fumaric acid and trimellitic anhydride shown in Table 1, as a catalyst, in a 10 L four-necked flask equipped with a thermometer, a stainless steel stirring rod, a downflow condenser having a dehydration tube, and a nitrogen introduction tube. 2-Ethylhexanoic acid tin (II) was added, the temperature was raised to 235° C. with stirring under a nitrogen atmosphere and maintained for 5 hours, and then the pressure in the flask was further reduced, and maintained at 8.3 kPa for 1 hour. .. Then, after cooling to 200° C. and returning to atmospheric pressure, fumaric acid, trimellitic anhydride, and 4-tert-butylcatechol were added, and after maintaining at a temperature of 210° C. for 4 hours, the content in the flask was further increased. The pressure was reduced and the reaction was carried out at 8.3 kPa until the softening point reached the temperature shown in Table 1 to obtain polyester resin a4. Table 1 shows the physical properties of the obtained resin a4.

[Production of aqueous dispersion of polyester resin particles]
Examples 1-1 to 1-7 and Comparative examples 1-1 to 1-2
(Process 1)
A 1 L four-necked flask equipped with a nitrogen introduction tube, a reflux condenser, a stirrer (manufactured by Shinto Kagaku Co., Ltd., trade name: Three One Motor BL300) and a thermocouple was used as the polyester resin a of the type shown in Table 2. 200 g of polyester resin was added and mixed with 200 g of MEK at 30° C. and dissolved to obtain a MEK solution of polyester resin. Then, the amount of the organic amine compound aqueous solution shown in Table 2 (each having a concentration of 25%) was added so that the pH of the resulting aqueous dispersion was 8.1 to 8.2, and the mixture was stirred for 30 minutes and neutralized. A solution of the prepared polyester resin was obtained.
In Comparative Example 1-1, an aqueous solution of sodium hydroxide (concentration: 5%) was used instead of the aqueous solution of the organic amine compound, and in Comparative Example 1-2, an aqueous solution of ammonia (concentration: 25%) was used instead of the aqueous solution of the organic amine compound. Was added.
(Process 2)
While maintaining the temperature in the flask at 30° C. and stirring, the total amount of deionized water was added dropwise to 100 g of the polyester resin at an addition rate of 10 g/min to invert the phase. Then, after raising the temperature to 60° C., MEK was distilled off while gradually reducing the pressure to 80 kPa to 30 kPa. After cooling to 25°C, the mixture was filtered through a 150-mesh wire net, the solid content concentration was adjusted to 30% with ion-exchanged water, and aqueous dispersions E-1 to E-7 and E-C1 to E containing polyester resin particles were prepared. -C2 was obtained. Table 2 shows the pH of each of the obtained aqueous dispersions and the volume average particle diameter of the polyester resin particles contained in the aqueous dispersions.

[Manufacture of inkjet recording ink]
Examples 2-1 to 2-7 and Comparative examples 2-1 to 2-2
2 parts of an aqueous dispersion containing polyester resin particles shown in Table 2 (solid content concentration 30%), 24 parts of an aqueous dispersion of pigment-containing polymer particles P-1 (solid content concentration 20%), 30 parts of diethylene glycol, polypropylene glycol 5 parts of 700 (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), 1.5 parts of acetylene glycol-based surfactant (manufactured by Air Products & Chemicals, trade name: Surfynol 465), and 100 parts of the total amount of ink. Ion-exchanged water was added to and mixed with. The obtained mixed liquid was filtered with a filter (manufactured by Sartorius, trade name: Minisart, pore size: 1.2 μm, material: cellulose acetate) to obtain each ink. Each of the obtained inks had a viscosity of 2.9 mPa·s and a pH of 8.6.
Each of the obtained inks was evaluated by the following evaluation methods. The results are shown in Table 2.

[Evaluation method]
(Continuous discharge stability)
Using an inkjet recording apparatus having a thermal head, a liquid-feeding tube of an inkjet recording apparatus (LPG-6010N manufactured by LG Electronics Co., Ltd.) was drawn out, and the tube was put into an ink tank and modified so that printing could be performed at a temperature of 25±1° C. In an environment of relative humidity of 30±5%, 100% duty printing was performed with a resolution of 1,600 dpi vertical×1,600 dpi horizontal in the best mode.
The continuous ejection stability was evaluated by continuously printing on A4 size plain paper (Office Max, All-in-One paper) and measuring the print density of the first print from the start of printing. The print density of the printed matter was measured every 1,000 sheets up to 000 sheets, and the number of prints at which the print density was lower than the print density of the first sheet was evaluated.
The printing density is the spectrophotometer/densitometer (manufactured by X-Rite Co., Ltd., trade name: the printing density of the printed matter printed on the plain paper obtained above (value output as black optical density)) It was measured using a SpectroEye, product number: RD914).
The measurement conditions were an observation viewing angle: 2 degrees, an observation light source: D65, a white reference: Abs, a polarizing filter: none, and a density reference: DIN.
The number of times of measurement was changed from one place to another, and an average value of a total of 5 points was used as the print density of the print.

(Fixability)
An ink jet recording device (Ricoh Co., Ltd., trade name: IPSiO GX5000, piezo system) was filled with each ink obtained in the examples and comparative examples, and coated paper (manufactured by Oji Paper Co., Ltd., trade name: OK Top) as a recording medium. A solid image having a size of 30 mm×30 mm was printed by using Coat Plus and water absorption: 4.9 g/m ² ) to obtain each printed matter.
After storing each of the obtained prints at room temperature of 25° C. for 24 hours, another coated paper (manufactured by Oji Paper Co., Ltd., product name: OK Top Coat Plus) is overlaid on the solid image of the prints, and further from above. With a load of 1,820 g (load area 43 mm×30 mm) being applied, the surface of the solid image was rubbed 30 times back and forth through the coated paper.
The optical density (OD value) of the solid image surface before and after rubbing was measured using the spectrocolorimeter/densitometer. The measurement conditions were the same as those for the evaluation of continuous ejection stability, and the number of times of measurement was changed at different measurement locations, a total of 10 points were measured, and the average value was obtained. Then, the ODLoss value (difference between OD values before and after rubbing) was calculated from the obtained OD values (average value) before and after rubbing by the following formula. The smaller the OD Loss value, the better the fixability.
OD Loss value=OD value before rubbing-OD value after rubbing

It can be seen from Table 2 that the inks of Examples 2-1 to 2-7 have significantly improved continuous ejection stability while maintaining excellent fixability as compared with the inks of Comparative Examples 2-1 to 2-2. I know that

Claims (8)

A method for producing an aqueous dispersion of polyester resin particles, comprising the following step 1 and step 2.
Step 1: A step of mixing the polyester resin a, the organic solvent, and the organic amine compound to obtain a solution of the polyester resin a neutralized with the organic amine compound Step 2: The neutralized solution obtained in Step 1 A step of adding an aqueous medium to a solution containing the polyester resin a to invert the phase to remove the organic solvent in the system to obtain an aqueous dispersion of polyester resin particles. The method for producing an aqueous dispersion according to claim 1, wherein the polyester resin a has an acid value of 10 mgKOH/g or more and 30 mgKOH/g or less. The method for producing an aqueous dispersion according to claim 1 or 2, wherein the organic amine compound is a tertiary amine. The method for producing an aqueous dispersion according to claim 1, wherein the organic amine compound has a total carbon number of 2 or more and 8 or less. The method for producing an aqueous dispersion according to claim 1, wherein the polyester resin a has a softening point of 125° C. or higher and 160° C. or lower. The method for producing an aqueous dispersion according to claim 1, wherein the volume average particle diameter of the polyester resin particles is 10 nm or more and 80 nm or less. An ink for inkjet recording, comprising an aqueous dispersion of polyester resin particles obtained by the method according to claim 1, and a colorant. The inkjet recording ink according to claim 7, wherein the colorant is particles of a water-insoluble polymer b containing a pigment.