JP6682857B2 - Water based ink - Google Patents

Description

  The present invention relates to an aqueous ink containing polyester resin particles, and an inkjet recording method using the aqueous ink.

  In the field of product label printing and commercial label printing used for advertising, etc., resin records such as PET (polyethylene terephthalate), PVC (polyvinyl chloride), PE (polyethylene), PP (polypropylene), NY (nylon), etc. Conventionally, printing has been performed on a medium with solvent-based ink, UV curable ink, or the like. On the other hand, from the viewpoints of environmental load reduction, energy saving, safety, etc., it is required to utilize an inkjet recording method or a flexographic printing method as a printing method using an aqueous ink. In particular, the ink jet recording method is a recording method in which ink droplets are directly ejected and attached to a recording member from a very fine nozzle to obtain a character or an image, full color is easy, and inexpensive, and Since plain paper can be used as a recording member and there are many advantages in that it is non-contact with an object to be printed, it is widely used. Therefore, it has been attempted to utilize the ink jet recording method for the resin recording medium.

For example, in Patent Document 1, an aqueous ink for inkjet recording containing a colorant and polyester resin particles, wherein the polyester resin constituting the polyester resin particles comprises a segment composed of a polyester resin and an addition polymerization resin. A segment contains a composite resin in which covalent bonds are formed, and the segment is derived from at least one of an acrylate ester having an alkyl group having 12 to 18 carbon atoms and a methacrylic acid ester having an alkyl group having 12 to 18 carbon atoms. A water-based ink for ink jet recording containing 5 to 50 mass% of a constituent unit in the above segment is described, and it is shown that it has excellent adhesion and gloss to a resin recording medium such as PET and PP. .
Further, in Patent Document 2, (a) one or more compounds selected from the group consisting of alkenylsuccinic acid, alkenylsuccinic anhydride, alkylsuccinic acid, and alkylsuccinic anhydride, and (b) Styrene-based monomer, and ink for inkjet recording using a resin for an aqueous pigment dispersion obtained by copolymerizing a composition containing a specific amount may have an extremely small number of coarse particles and have excellent ejection stability. It is shown.
Further, in Patent Document 3, a water-based ink in which a pigment is dispersed contains a substantially colorless and transparent polyester suspension, and the water-based ink is fixable to an object to be printed such as paper or an OHP sheet. It is also shown that it has excellent water resistance.

JP, 2005-124353, A JP 2012-219143 A JP, 10-46081, A

However, in the prior art, it was necessary to improve the adhesion of the water-based ink, which has a low environmental load and high safety, to the resin recording medium. Further, when the polyester resin particles are contained for the purpose of improving the adhesiveness, the hydrolysis of the polyester in the ink is also a problem, and there is a problem in the stability of the ink.
Therefore, the present invention provides an aqueous ink having excellent adhesion to a resin recording medium and hydrolysis resistance, and an inkjet recording method using the aqueous ink.

  The present inventors have found that an aqueous ink containing polyester resin particles containing polyester having a specific constitutional unit can solve the above problems.

That is, the present invention relates to the following [1] or [2].
[1] A water-based ink containing a colorant and polyester resin particles,
The polyester contained in the polyester resin particles is a polycondensate of an alcohol component and a carboxylic acid component,
As the alcohol component, a propylene oxide adduct of bisphenol A is contained in the alcohol component in an amount of 50 mol% or more and 100 mol% or less,
As the carboxylic acid component, succinic acid substituted with an alkyl group having 1 to 20 carbon atoms or an alkenyl group having 2 to 20 carbon atoms is contained in the carboxylic acid component in an amount of 10 mol% to 50 mol%, and further 3 An aqueous ink containing a polyvalent carboxylic acid having a valence of 3 or more.
[2] An ink jet system in which the water-based ink according to the above [1] is attached to a resin recording medium by an ink jet recording method, and then the resin recording medium to which the water based ink is attached is heated to 40 ° C. or more and 100 ° C. or less. Recording method.

  According to the present invention, it is possible to provide an aqueous ink having excellent adhesion to a resin recording medium and hydrolysis resistance, and an inkjet recording method using the aqueous ink.

[Water-based ink]
The water-based ink of the present invention contains a colorant and polyester resin particles. In the water-based ink, the polyester contained in the polyester resin particles is a polycondensation product of an alcohol component and a carboxylic acid component, and a propylene oxide adduct of bisphenol A in the alcohol component is 50 mol% or more and 100 mol% or less as the alcohol component. The carboxylic acid component contains succinic acid substituted with an alkyl group having 1 to 20 carbon atoms or an alkenyl group having 2 to 20 carbon atoms in the carboxylic acid component in an amount of 10 mol% to 50 mol% inclusive, and It contains a trivalent or higher polycarboxylic acid.

The reason why the water-based ink of the present invention is excellent in adhesion to a resin recording medium and hydrolysis resistance is not clear, but it is considered as follows.
The water-based ink of the present invention (hereinafter, also simply referred to as “ink”) contains a colorant and polyester resin particles. When the ink adheres to the resin-made recording medium during printing, the polyester contained in the polyester resin particles diffuses on the printing surface of the recording medium and acts as a fixing aid for the colorant. Here, the polyester is a polycondensation product of an alcohol component and a carboxylic acid component, and contains a propylene oxide adduct of bisphenol A as an alcohol component in an amount of 50 mol% or more and 100 mol% or less. Further, the polyester contains 10 mol% or more and 50 mol% or less of succinic acid substituted with an alkyl group having 1 to 20 carbon atoms or an alkenyl group having 2 to 20 carbon atoms as a carboxylic acid component in the carboxylic acid component. However, it further contains a trivalent or higher polyvalent carboxylic acid.
By using a specific amount of a propylene oxide adduct of bisphenol A and a specific amount of a succinic acid substituted with an alkyl group having 1 to 20 carbon atoms or an alkenyl group having 2 to 20 carbon atoms as a raw material monomer for polyester , A propylene oxide adduct of bisphenol A has increased hydrophobicity in a molecular chain, and a highly polar ester bond site and a less polar alkyl group or alkenyl group are present, and are present at appropriate intervals in the molecular chain. It will be. As a result, the polyester strongly interacts with the polar group of the resin in the resin recording medium having a polarity such as PVC, so that the adhesion of the ink of the present invention to the resin recording medium is improved. Conceivable.
In the water-based ink of the present invention, the polyester is trivalent with the alkyl group or alkenyl group of succinic acid substituted with an alkyl group having 1 to 20 carbon atoms or an alkenyl group having 2 to 20 carbon atoms. Since the crosslinked structure derived from the polycarboxylic acid component described above enhances the hydrophobicity around the ester bond, it is considered that the hydrolysis of the polyester in the water-based ink can be effectively suppressed.

<Polyester resin particles>
The polyester resin particles (hereinafter, also simply referred to as “resin particles”) used in the present invention include polyester which is a polycondensate of an alcohol component and a carboxylic acid component.

(polyester)
The polyester used in the present invention contains a polyester which is a polycondensation product of an alcohol component and a carboxylic acid component, from the viewpoint of improving adhesion to a resin recording medium and hydrolysis resistance, and the bisphenol A of bisphenol A is used as the alcohol component. A propylene oxide adduct is contained in the alcohol component in an amount of 50 mol% or more and 100 mol% or less. Then, as the carboxylic acid component, succinic acid substituted with an alkyl group having 1 to 20 carbon atoms or an alkenyl group having 2 to 20 carbon atoms is contained in the carboxylic acid component in an amount of 10 mol% to 50 mol%, Further, it contains a polyvalent carboxylic acid having a valence of 3 or more.
From the viewpoint of improving the dispersion stability of the polyester resin particles in an aqueous medium, the polyester preferably has an acid group at the molecular chain terminal. Examples of the acid group include a carboxy group, a sulfonic acid group, a phosphonic acid group, a sulfinic acid group, and the like, and a carboxy group is preferable from the viewpoint of improving the dispersion stability of resin particles in an aqueous medium.

As the alcohol component used in the present invention, a propylene oxide adduct of bisphenol A is contained in the alcohol component in an amount of 50 mol% or more and 100 mol% or less from the viewpoint of improving adhesion to a resin recording medium.
The content of the propylene oxide adduct of bisphenol A in the alcohol component is 50 mol% or more, preferably 60 mol% or more, and more preferably 65 mol% from the viewpoint of improving the adhesion to the resin recording medium. The above is more preferably 70 mol% or more, still more preferably 80 mol% or more, still more preferably 90 mol% or more, and 100 mol% or less.

The average addition mole number of propylene oxide of the propylene oxide adduct of bisphenol A used in the present invention is preferably 1 or more, more preferably 1.2 or more, and further preferably from the viewpoint of improving adhesion to a resin recording medium. Is 1.5 or more, and preferably 16 or less, more preferably 12 or less, still more preferably 8 or less, even more preferably 4 or less.
The propylene oxide adduct of bisphenol A is preferably polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane.

As the alcohol component, other than the propylene oxide adduct of bisphenol A, a diol, a polyhydric alcohol having 3 or more valences, or the like may be contained.
Examples of the diol include an aliphatic diol having a main chain carbon number of 2 or more and 12 or less, an aromatic diol, and an alicyclic diol.
Examples of the aliphatic diol having a main chain carbon number of 2 or more and 12 or less include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, neopentyl glycol, Examples thereof include 1,6-hexanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol and 1,12-dodecanediol.

Examples of the aromatic diol include aromatic diols such as bisphenol A and ethylene oxide (average addition mole number of 1 to 16) adducts thereof. The average number of moles of ethylene oxide added to the ethylene oxide adduct of bisphenol A is preferably 1 or more, more preferably 1.2 or more, and still more preferably 1.5 or more, from the viewpoint of improving the adhesion to a resin recording medium. And preferably 16 or less, more preferably 12 or less, still more preferably 8 or less, still more preferably 4 or less.
Examples of the alicyclic diol include cyclohexanediol, cyclohexanedimethanol, hydrogenated bisphenol A and the like.
Examples of the trihydric or higher polyhydric alcohol include glycerin, pentaerythritol, trimethylolpropane and sorbitol.
Among these, an ethylene oxide adduct of bisphenol A is preferable, and polyoxyethylene (2.2) -2,2-bis (4-hydroxyphenyl) propane is more preferable.
The said alcohol component can be used individually by 1 type or in combination of 2 or more types.

  The carboxylic acid component used in the present invention contains 10 mol% to 50 mol% of succinic acid substituted with an alkyl group having 1 to 20 carbon atoms or an alkenyl group having 2 to 20 carbon atoms in the carboxylic acid component, Further, it contains a polyvalent carboxylic acid having a valence of 3 or more. The carboxylic acid component includes not only carboxylic acids, but also their anhydrides and their alkyl esters having 1 to 3 carbon atoms. That is, in the present specification, when only the name of carboxylic acid is described, it is assumed that the anhydride of the carboxylic acid and the alkyl ester having 1 to 3 carbon atoms are also included.

When the substituent of succinic acid (hereinafter, also simply referred to as “substituted succinic acid”) substituted with an alkyl group having 1 to 20 carbon atoms or an alkenyl group having 2 to 20 carbon atoms used in the present invention is an alkyl group. The carbon number of the alkyl group is preferably 4 or more, more preferably 6 or more, still more preferably 8 or more, and preferably 18 or less, more preferably 16 or less, still more preferably 14 or less.
When the substituent of the substituted succinic acid used in the present invention is an alkenyl group, the carbon number of the alkenyl group is preferably 4 or more, more preferably 6 or more, further preferably 8 or more, and preferably 18 or more. Or less, more preferably 16 or less, still more preferably 14 or less.
Specific examples of the substituted succinic acid include dodecyl succinic acid, dodecenyl succinic acid and octenyl succinic acid. Among these, at least one selected from the group consisting of dodecyl succinic acid and dodecenyl succinic acid is preferable, from the viewpoint of improving adhesion to a resin recording medium and hydrolysis resistance, more preferably dodecyl succinic anhydride. And at least one selected from the group consisting of dodecenyl succinic anhydride, and more preferably dodecenyl succinic anhydride.

  The content of the substituted succinic acid is 10 mol% or more, preferably 15 mol% or more, more preferably 25 mol% in the carboxylic acid component from the viewpoint of improving the adhesion to a PVC recording medium and the hydrolysis resistance. Mol% or more, more preferably 28 mol% or more, even more preferably 30 mol% or more, even more preferably 35 mol% or more, even more preferably 40 mol% or more, and 50 mol% or less, preferably It is 48 mol% or less, more preferably 47 mol% or less.

The trivalent or higher polyvalent carboxylic acid used in the present invention is preferably a trivalent or higher aromatic carboxylic acid, and the trivalent or higher aromatic carboxylic acid preferably has 8 or more carbon atoms, more preferably 9 carbon atoms. Above, and preferably 16 or less, more preferably 14 or less.
Examples of the trivalent or higher polyvalent carboxylic acid include trimellitic acid, 2,5,7-naphthalenetricarboxylic acid and pyromellitic acid. From the viewpoint of improving the adhesion to the resin-made recording medium and the hydrolysis resistance, it is preferably trimellitic acid, and of these, from the same viewpoint, trimellitic acid and its anhydride, more preferably, It is trimellitic anhydride.
The content of the trivalent or higher polycarboxylic acid is preferably 4 mol% or more, more preferably 8 mol, in the carboxylic acid component, from the viewpoint of improving the adhesion to the resin recording medium and the hydrolysis resistance. % Or more, more preferably 9 mol% or more, and preferably 25 mol% or less, more preferably 20 mol% or less, further preferably 15 mol% or less, even more preferably 11 mol% or less.

The carboxylic acid component preferably further includes a dicarboxylic acid other than the substituted succinic acid.
Examples of the dicarboxylic acid include at least one selected from the group consisting of aromatic dicarboxylic acids, aliphatic dicarboxylic acids, and alicyclic dicarboxylic acids.
Examples of the aromatic dicarboxylic acid include phthalic acid, isophthalic acid, terephthalic acid and the like. From the viewpoint of improving the adhesion to a resin recording medium and the hydrolysis resistance, terephthalic acid is preferable.
Examples of the aliphatic dicarboxylic acid include fumaric acid, adipic acid, sebacic acid, maleic acid, azelaic acid, succinic acid and the like, and from the viewpoint of improving adhesion to a resin recording medium and hydrolysis resistance, preferably , Fumaric acid, adipic acid, and sebacic acid, at least one selected from the group consisting of fumaric acid, adipic acid, and fumaric acid.
Examples of the alicyclic dicarboxylic acid include cyclohexanedicarboxylic acid.

  The content of the dicarboxylic acid other than the substituted succinic acid is preferably 25 mol% or more, more preferably 40 mol% in the carboxylic acid component, from the viewpoint of improving the adhesion to the recording medium made of resin and the hydrolysis resistance. The above is more preferably 43 mol% or more, and preferably 65 mol% or less, more preferably 60 mol% or less, further preferably 55 mol% or less, still more preferably 50 mol% or less.

The total content of dicarboxylic acids in the carboxylic acid component is preferably 75 mol% or more, more preferably 80 mol% or more, further preferably from the viewpoint of improving adhesion to a resin recording medium and hydrolysis resistance. Is 85 mol% or more, more preferably 89 mol% or more, and preferably 96 mol% or less, more preferably 92 mol% or less, still more preferably 91 mol% or less.
The carboxylic acid components may be used alone or in combination of two or more.

  The molar 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 used in the present invention determines the adhesion to the resin recording medium and the hydrolysis resistance. From the viewpoint of improvement, it is preferably 0.65 or more, more preferably 0.80 or more, and preferably 1.20 or less, more preferably 1.10 or less.

  The softening point of the polyester is preferably 70 ° C. or higher, more preferably 80 ° C. or higher, even more preferably 90 ° C. or higher, from the viewpoint of improving the adhesion to a resin recording medium and the hydrolysis resistance, and The temperature is preferably 165 ° C or lower, more preferably 130 ° C or lower, still more preferably 125 ° C or lower.

  The glass transition temperature of the polyester is preferably 35 ° C. or higher, more preferably 40 ° C. or higher, even more preferably 50 ° C. or higher, from the viewpoint of improving adhesion to a resin recording medium and hydrolysis resistance. , Preferably 95 ° C. or lower, more preferably 80 ° C. or lower, further preferably 70 ° C. or lower, still more preferably 65 ° C. or lower.

  The acid value of the polyester is preferably 5 mgKOH / g or more, more preferably 10 mgKOH / g or more, further preferably 15 mgKOH / g or more, from the viewpoint of improving the dispersion stability of the polyester resin particles in an aqueous medium. And, it is preferably 35 mgKOH / g or less, more preferably 30 mgKOH / g or less, further preferably 25 mgKOH / g or less, still more preferably 20 mgKOH / g or less.

With respect to the softening point, glass transition temperature, and acid value of the polyester, any desired one can be obtained by appropriately adjusting the types of monomers used in the production of polyester, the compounding ratio, the temperature of polycondensation, and the reaction time. It is possible, and those values are calculated by the method described in Examples below.
The polyesters may be used alone or in combination of two or more.
When two or more polyesters are mixed and used, the softening point, the glass transition temperature and the acid value are the values obtained by the method described in the examples as a mixture of the two or more polyesters.

[Method for producing polyester]
The polyester used in the present invention can be produced by subjecting an alcohol component and a carboxylic acid component to a polycondensation reaction. For example, the alcohol component and the carboxylic acid component are mixed in an inert gas atmosphere at a temperature of 120 ° C. or higher and 250 ° C. or lower by using an esterification catalyst, an esterification promoter, and a polymerization inhibitor as needed. It can be produced by condensation.

As the esterification catalyst, an esterification catalyst such as a tin compound such as dibutyltin oxide or di (2-ethylhexanoic acid) tin or a titanium compound such as titanium diisopropylate bistriethanolaminate can be used.
The amount of the esterification catalyst used is not limited, but is preferably 0.01 parts by mass or more, more preferably 0.05 parts by mass or more, relative to 100 parts by mass of the total amount of the alcohol component and the carboxylic acid component, And it is preferably 1.5 parts by mass or less, more preferably 1.0 parts by mass or less.

As the esterification promoter, pyrogallol, 3,4,5-trihydroxybenzoic acid (the same as "gallic acid"), pyrogallol compounds such as gallic acid ester; 2,3,4-trihydroxybenzophenone, 2,2 Benzophenone derivatives such as', 3,4-tetrahydroxybenzophenone; and catechin derivatives such as epigallocatechin and epigallocatechin gallate.
The amount of the esterification promoter used is preferably 0.001 part by mass or more, more preferably 0.01 part by mass or more, and preferably 100 parts by mass with respect to the total amount of 100 parts by mass of the alcohol component and the carboxylic acid component. Is 0.5 parts by mass or less, more preferably 0.2 parts by mass or less.

  Further, examples of the polymerization inhibitor include 4-tert-butylcatechol. The amount of the polymerization inhibitor used is preferably 0.001 parts by mass or more, more preferably 0.005 parts by mass or more, and preferably 100 parts by mass with respect to the total amount 100 parts by mass of the alcohol component and the carboxylic acid component. The amount is 0.5 parts by mass or less, more preferably 0.1 parts by mass or less.

  The polyester may also include polyester modified so as not to substantially impair its properties. As the modified polyester, for example, a composite resin having a segment composed of an addition polymerization type resin, JP-A No. 11-133668, and JP-A No. 10-239903 can be prepared by the method described in JP-A-2015-124353. Examples thereof include polyester grafted or blocked with phenol, urethane, epoxy, or the like by the method described in JP-A-8-20636 or the like, and composite resins having two or more resin units including a polyester unit.

In the polyester resin particles used in the present invention, the content of the polyester is preferably 60% by mass or more, more preferably 80% by mass or more, from the viewpoint of improving adhesion to a resin recording medium and hydrolysis resistance. The content is more preferably 90% by mass or more, still more preferably 98% by mass or more, still more preferably 100% by mass.
Further, the polyester resin particles used in the present invention may contain a resin other than polyester, for example, a resin such as a styrene-acrylic copolymer, an epoxy resin, a polycarbonate, or a polyurethane, as long as the effect of the present invention is not impaired. .
Further, the polyester resin particles may contain, as an optional component, a reinforcing filler such as a fibrous substance, an additive such as an antioxidant and an anti-aging agent, etc., as long as the effects of the present invention are not impaired.

(Method for producing polyester resin particles)
The polyester resin particles used in the present invention are preferably produced by a method in which the above-mentioned resin containing polyester is dispersed in an aqueous medium to obtain an aqueous dispersion of polyester resin particles.

  As the aqueous medium, one containing water as a main component is preferable. The content of water in the aqueous medium is preferably 80% by mass or more, more preferably 90% by mass or more, and further preferably from the viewpoint of improving the dispersion stability of the aqueous dispersion of resin particles and the viewpoint of environmental safety. It is 100% by mass. As water, deionized water, ion-exchanged water or distilled water is preferably used. Components other than water that can form an aqueous medium together with water include alkyl alcohol solvents having 1 to 5 carbon atoms such as methanol, ethanol, isopropanol, butanol; dialkyl ketones having 3 to 5 carbon atoms such as acetone and methyl ethyl ketone. System solvents: Organic solvents that dissolve in water, such as ether solvents such as tetrahydrofuran.

  As a method for obtaining an aqueous dispersion of the polyester resin particles, a method of adding the resin containing the polyester to an aqueous medium and carrying out a dispersion treatment with a disperser or the like, gradually adding the aqueous medium to the resin containing the polyester Examples of the method include a phase inversion emulsification method (hereinafter, also referred to as “phase inversion emulsification method”) and the like. From the viewpoint of obtaining an aqueous ink excellent in adhesion to a resin recording medium and hydrolysis resistance, the phase inversion emulsification method is preferable. As the phase inversion emulsification method, it is preferable to first prepare a solution in which the resin containing the polyester is dissolved in an organic solvent, then add an aqueous medium to the solution for phase inversion, and then remove the organic solvent. . Hereinafter, the phase inversion emulsification method will be described.

[Phase inversion emulsification method]
As the phase inversion emulsification method, first, the resin containing polyester is dissolved in an organic solvent to obtain a solution containing polyester.
When a plurality of types of polyesters or resins other than polyesters are contained, a mixture of these polyesters and other resins may be used in advance, but these resins are simultaneously added to an organic solvent to be dissolved, You may obtain the solution containing.
In addition, it is preferable to use a basic aqueous solution from the viewpoint of improving the affinity of the resin containing polyester with the aqueous medium and improving the dispersion stability of the aqueous dispersion of the resin particles.
As a method for obtaining a solution containing polyester, a method in which a resin containing polyester and an organic solvent are placed in a container to be dissolved and then a basic aqueous solution is placed in the container and stirred by a stirrer to obtain the solution is preferable.
The operation of dissolving the resin containing polyester in the organic solvent and the subsequent addition of the basic aqueous solution are usually performed at a temperature not higher than the boiling point of the organic solvent used.

  Examples of the organic solvent include ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and diethyl ketone; ether solvents such as dibutyl ether, tetrahydrofuran, and dioxane; acetic ester solvents such as ethyl acetate and isopropyl acetate; dichloromethane, Examples thereof include alkyl halide solvents such as chloroform. Among these, from the viewpoint of easy removal from the resin particles after addition of the aqueous medium, the aqueous medium and the mixed solution of the organic solvent, preferably at least one selected from a ketone solvent and an acetic acid ester solvent, More preferred is at least one selected from methyl ethyl ketone, ethyl acetate and isopropyl acetate, and even more preferred is methyl ethyl ketone.

  The mass ratio of the organic solvent to the resin in the resin particles (organic solvent / resin) is preferably 0 from the viewpoint of dissolving the resin to facilitate phase inversion into an aqueous medium and improving the dispersion stability of the resin particles. 0.3 or more, more preferably 0.5 or more, still more preferably 0.7 or more, and preferably 5.0 or less, more preferably 3.0 or less, still more preferably 2.5 or less.

  Examples of the basic compound used in the basic aqueous solution include alkali metal hydroxides such as lithium hydroxide, sodium hydroxide, and potassium hydroxide; ammonia, trimethylamine, ethylamine, diethylamine, triethylamine, diethanolamine, triethanolamine, and triethanolamine. Examples include nitrogen-containing basic substances such as butylamine. Among these, sodium hydroxide or ammonia is preferable from the viewpoint of improving the dispersion stability of the resin particles.

The equivalent amount (mol%) of the basic compound used with respect to the acid group of the resin is preferably 10 mol% or more, more preferably 50 mol% or more, and preferably from the viewpoint of improving the dispersion stability of the resin particles. It is 150 mol% or less, more preferably 120 mol% or less, and further preferably 100 mol% or less.
The equivalent amount (mol%) of the basic compound used can be calculated by the following formula. When the equivalent of the basic compound is 100 mol% or less, it has the same meaning as the neutralization degree. When the equivalent of the neutralizing agent is more than 100 mol% in the following formula, the neutralizing agent is an acid group of the resin. Is excessive, and the degree of neutralization of the resin at this time is considered to be 100 mol%.
Equivalent amount of basic compound used (mol%) = [{addition mass of basic compound (g) / equivalent amount of basic compound} / [{acid value of resin (mgKOH / g) × mass of resin (g)} / (56 × 1000)]] × 100
The concentration of the basic compound in the basic aqueous solution is preferably 1% by mass or more, more preferably 3% by mass or more, from the viewpoint of improving the dispersion stability and productivity of the aqueous dispersion of resin particles, and, It is preferably 60% by mass or less, more preferably 50% by mass or less.

Next, an aqueous medium is added to the solution containing the polyester to invert the phase.
The amount of the aqueous medium added is preferably 100 parts by mass or more, more preferably 150 parts by mass or more, and still more preferably 200 parts by mass or more with respect to 100 parts by mass of the resin, from the viewpoint of improving the dispersion stability of the resin particles. And preferably 900 parts by mass or less, more preferably 500 parts by mass or less, still more preferably 350 parts by mass or less, still more preferably 300 parts by mass or less.
From the viewpoint of improving the dispersion stability of the resin particles, and improving the adhesion to the resin recording medium and the hydrolysis resistance, the addition rate of the aqueous medium is 100 parts by mass of the resin until the phase inversion is completed. On the other hand, it is preferably 1 part by mass / min or more, more preferably 3 parts by mass / min or more, further preferably 5 parts by mass / min or more, and preferably 50 parts by mass / min or less, more preferably 30 parts by mass or more. It is not more than 20 parts by mass, preferably not more than 20 parts by mass. There is no limitation on the addition rate of the aqueous medium after the phase inversion.

  The mass ratio of the aqueous medium to the organic solvent (aqueous medium / organic solvent) after the total amount of the aqueous medium is added is preferably 40/60 or more, more preferably 50/50 or more, further preferably 55/45 or more. And preferably 90/10 or less, more preferably 80/20 or less, still more preferably 70/30 or less.

  The temperature at which the aqueous medium is mixed is preferably 10 ° C. or higher, more preferably 20 ° C. or higher, further preferably 25 ° C. or higher, and preferably 80 ° C., from the viewpoint of improving the dispersion stability of the resin particles. Or less, more preferably 65 ° C. or less, still more preferably 50 ° C. or less.

After the phase inversion emulsification, it may have a step of removing the organic solvent from the obtained mixed solution of the resin particles, the aqueous medium and the organic solvent, if necessary. As a method of removing the organic solvent, it is preferable to distill since the organic solvent is dissolved in water. In this case, it is preferable to elevate the temperature to a temperature equal to or higher than the boiling point of the organic solvent used while stirring and distill off. From the viewpoint of maintaining the dispersion stability of the resin particles, it is more preferable to distill under reduced pressure. It should be noted that the temperature may be reduced and then raised, or the temperature may be raised and then reduced.
The organic solvent may not be completely removed and may remain in the aqueous dispersion of resin particles. In this case, the residual amount of the organic solvent in the aqueous dispersion of the obtained resin particles is preferably 1% by mass or less, more preferably 0.5% by mass or less, further preferably 0.1% by mass in the aqueous dispersion. It is the following.

The aqueous dispersion of polyester resin particles thus obtained is preferably filtered through a wire mesh or the like to remove coarse particles and the like. Further, when the organic solvent is removed, water is also azeotropically reduced together with the organic solvent. Therefore, it is preferable to add water to adjust the solid content concentration of the aqueous dispersion.
The solid content concentration of the aqueous dispersion of the polyester resin particles after adjusting the solid content concentration is preferably from the viewpoint of improving the productivity of the ink, and the viewpoint of improving the adhesion to the resin recording medium and the hydrolysis resistance. Is 10% by mass or more, more preferably 20% by mass or more, further preferably 25% by mass or more, and preferably 50% by mass or less, more preferably 45% by mass or less, further preferably 40% by mass or less. .
The solid content in determining the solid content concentration is the total amount of the resin and non-volatile components such as optional components such as a surfactant and a colorant that can be added as necessary.

The volume average particle diameter (D _V ) of the polyester resin particles in the aqueous dispersion is preferably 20 nm or more, more preferably 50 nm or more, from the viewpoint of improving the adhesion to the resin recording medium and the hydrolysis resistance. It is preferably 60 nm or more, more preferably 70 nm or more, and preferably 500 nm or less, more preferably 300 nm or less, further preferably 100 nm or less, even more preferably 90 nm or less. The volume average particle diameter (D _V ) is measured by a dynamic light scattering method, and is determined by the method described in Examples below.

<Colorant>
The colorant used in the present invention refers to a pigment or a dye. Further, the colorant may be a fine particle that is stable in the ink, using a surfactant or a dispersing polymer.
Examples of the colorant used in the present invention include pigments, hydrophobic dyes, water-soluble dyes (acid dyes, reactive dyes, direct dyes, etc.). Among these, from the viewpoint of improving the dispersion stability of the ink, the water resistance of the printed matter, the glossiness, and the surface smoothness, at least one selected from pigments and hydrophobic dyes is preferable, and pigment is more preferable. As the colorant, one kind may be used alone, or two or more kinds may be used in combination at an arbitrary ratio.

The pigment may be either an inorganic pigment or an organic pigment.
Examples of the inorganic pigment include carbon black and metal oxides. When used in black ink, carbon black is preferable.
Examples of organic pigments include cyan pigments, yellow pigments, magenta pigments, and black pigments. As the cyan pigment, a phthalocyanine pigment is preferable, and copper phthalocyanine is more preferable. As the yellow pigment, a monoazo pigment, an isoindoline pigment, and a benzimidazolone pigment are preferable. As the magenta pigment, a soluble azo pigment such as a quinacridone pigment and a BONA lake pigment, and an insoluble azo pigment such as a naphthol AS pigment are preferable.
The organic pigment is preferably C.I. I. Pigment Yellow, C.I. I. Pigment Red, C.I. I. Pigment Orange, C.I. I. Pigment violet, C.I. I. Pigment Blue, and C.I. I. Pigment Green. One or more kinds of each product number selected from the group consisting of Pigment Green.

Further, in the present invention, a self-dispersion pigment can also be used. The self-dispersion type pigment is a hydrophilic functional group (an anionic hydrophilic group such as a carboxy group or a sulfonic acid group, or a cationic hydrophilic group such as a quaternary ammonium group) which is directly or other atomic group. It means an inorganic pigment or an organic pigment that can be dispersed in an aqueous medium without using a surfactant or a resin by being bound to the surface of the pigment via the. Here, examples of the other atomic group include an alkanediyl group having 1 to 12 carbon atoms, a phenylene group, a naphthylene group, and the like.
The pigments may be used alone or as a mixture of two or more kinds in an arbitrary ratio.

The hydrophobic dye means a dye having a solubility of preferably less than 6% by mass in 100 g of water (20 ° C.). Examples of hydrophobic dyes include oil-soluble dyes and disperse dyes.
The dyes may be used alone or in combination of two or more kinds in an arbitrary ratio.

The content of the colorant in the ink 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 improving the dispersion stability and the image density of the ink, and , Preferably 25% by mass or less, more preferably 10% by mass or less, still more preferably 5% by mass or less.
The mass ratio of the colorant to the polyester resin particles [colorant / polyester resin particles] is preferably 10/90 or more, more preferably 10/90 or more in the ink from the viewpoint of improving the adhesion to the resin recording medium and the hydrolysis resistance. It is preferably 20/80 or more, more preferably 30/70 or more, still more preferably 40/60 or more, and preferably 80/20 or less, more preferably 70/30 or less, further preferably 60/40 or less. , And more preferably 50/50 or less.

(Polymer particles containing colorant)
The colorant is preferably a polymer, a surfactant, or the like, and is made into stable fine particles in the ink. That is, the colorant is preferably used as a colorant dispersed with a polymer dispersant or as polymer particles containing the colorant, from the viewpoint of improving the dispersion stability and image density of the ink, and the surface smoothness of the printed matter. From the viewpoint of improving the colorant, it is more preferable to use it as polymer particles containing a colorant.

The volume average particle diameter (D _V ) of the polymer particles containing a colorant is preferably 40 nm or more, more preferably 50 nm or more, and preferably 200 nm or less, more preferably 150 nm, from the viewpoint of improving the image density. It is the following. The volume average particle diameter (D _V ) of the polymer particles containing a colorant is measured by the dynamic light scattering method, and specifically, it is measured by the method of the examples.

From the viewpoint of improving the water dispersibility of the polymer particles in the ink and the image density, it is preferable to use a water-insoluble polymer as the polymer particles containing the colorant. Here, the "water-insoluble polymer" refers to a polymer having a dissolved amount of 10 g or less when the polymer which has been dried at 105 ° C for 2 hours to reach a constant amount is dissolved in 100 g of water at 25 ° C, The amount of dissolution is preferably 5 g or less, more preferably 1 g or less. In the case of an anionic polymer, the amount of dissolution is the amount of dissolution when the anionic groups of the polymer are 100% neutralized with sodium hydroxide.
Examples of the water-insoluble polymer include polyester, polyurethane, and vinyl-based polymers. From the viewpoint of improving the storage stability of the ink, it is preferably obtained by addition polymerization of a vinyl monomer (vinyl compound, vinylidene compound, vinylene compound). It is a vinyl polymer.
As the vinyl polymer, those having a constitutional unit derived from an ionic monomer and a constitutional unit derived from a hydrophobic monomer are preferable from the viewpoint of improving the storage stability and the ejection property of the ink.

The ionic monomer is preferably an anionic monomer from the viewpoint of improving the dispersion stability of the polymer particles containing the colorant in the ink. Examples of the anionic monomer include a carboxylic acid monomer, a sulfonic acid monomer, and a phosphoric acid monomer. Examples of the carboxylic acid monomer include acrylic acid, methacrylic acid, maleic acid, fumaric acid, 2-methacryloyloxymethylsuccinic acid and the like.
Among the anionic monomers, a carboxylic acid monomer is preferable, and at least one selected from acrylic acid and methacrylic acid is more preferable, from the viewpoint of improving the dispersion stability of the polymer particles containing the colorant in the ink.
The amount of the ionic monomer component is preferably 2% by mass or more, more preferably 5% by mass or more, in the water-insoluble polymer, from the viewpoint of improving the dispersion stability of the polymer particles containing the colorant in the ink. It is more preferably 8% by mass or more, and preferably 40% by mass or less, more preferably 30% by mass or less, and further preferably 25% by mass or less.
The content can be calculated from the blending amount of each monomer component.

The hydrophobic monomer is preferably an alkyl (meth) acrylate having an alkyl group having 1 or more carbon atoms, more preferably 6 or more carbon atoms, and preferably 22 or less carbon atoms, more preferably 18 or less carbon atoms; styrene, Examples include styrene-based monomers such as 2-methylstyrene and divinylbenzene; aromatic group-containing (meth) acrylates such as benzyl (meth) acrylate and phenoxyethyl (meth) acrylate, and preferably styrene and benzyl (meth) acrylate. is there. In addition, "(meth) acrylate" shows at least 1 sort (s) chosen from an acrylate and a methacrylate.
From the viewpoint of improving the dispersion stability of the polymer particles containing a colorant in the ink, benzyl (meth) acrylate is more preferable.

The amount of the hydrophobic monomer component is preferably 5% by mass or more, more preferably 10% by mass or more in the water-insoluble polymer from the viewpoint of improving the dispersion stability of the polymer particles containing the colorant in the ink. And preferably not more than 98% by mass, more preferably not more than 80% by mass.
The content can be calculated from the blending amount of each monomer component.

As the vinyl-based polymer, from the viewpoint of improving the dispersion stability of the polymer particles containing a colorant in the ink, a number average molecular weight of 500 having a polymerizable functional group such as a (meth) acryloyloxy group at one end is 500. Above, preferably 1,000 or more, and 100,000 or less, preferably 10,000 or less macromer, and a nonionic monomer having a polyoxyalkylene glycol chain may be contained.
The amount of the macromer and the nonionic monomer component is preferably 1% by mass or more, more preferably 1% by mass or more, in the water-insoluble polymer, from the viewpoint of improving the dispersion stability of the polymer particles containing a colorant in the ink. Is 5% by mass or more, and preferably 50% by mass or less, more preferably 40% by mass or less, further preferably 30% by mass or less, still more preferably 20% by mass or less.
The content can be calculated from the blending amount of each monomer component.

  The monomer component of the vinyl polymer may be used alone or in combination of two or more.

  The weight average molecular weight (Mw) of the water-insoluble polymer is preferably 5,000 or more, from the viewpoint of improving the dispersion stability of the polymer particles containing the colorant in the ink and the image density. It is preferably 10,000 or more, more preferably 20,000 or more, and preferably 500,000 or less, more preferably 400,000 or less, further preferably 300,000 or less, still more preferably 200,000 or less. Is. The weight average molecular weight (Mw) can be measured by the method described in Examples.

The water-insoluble polymer is produced by copolymerizing a monomer mixture by a known polymerization method. As a preferable example of the polymerization method, a solution polymerization method in which a monomer mixture 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 from the reaction solution by a known method such as reprecipitation or solvent removal.

[Method for producing polymer particles containing a colorant]
The polymer particles containing the colorant, for example, a dispersion treatment of a mixture containing a water-insoluble polymer, an organic solvent, a colorant, water, and optionally a neutralizing agent, a surfactant, etc. It can be produced by a method of obtaining an aqueous dispersion of polymer particles containing a colorant by obtaining an aqueous dispersion of polymer particles containing the colorant, after obtaining a dispersion of the containing polymer particles.

There is no limitation on the organic solvent in which the water-insoluble polymer is dissolved, but aliphatic alcohols having 1 to 3 carbon atoms, ketones having 3 to 5 carbon atoms, ethers, esters and the like are preferable, and ketones are more preferable. Methyl ethyl ketone is more preferred. When the water-insoluble polymer is synthesized by the solution polymerization method, the solvent used for the polymerization may be used as it is.
When the water-insoluble polymer is an anionic polymer, a neutralizing agent may be used to neutralize the anionic groups in the water-insoluble polymer. When a neutralizing agent is used, it is preferably neutralized so that the pH becomes 7 or more and 11 or less. Examples of the neutralizing agent include alkali metal hydroxides such as lithium hydroxide, sodium hydroxide and potassium hydroxide; bases such as ammonia and various amines. Further, the water-insoluble polymer may be neutralized in advance.

In the aqueous dispersion of polymer particles containing a colorant, the colorant is preferably 5% by mass or more, more preferably 10% by mass, from the viewpoint of improving the dispersion stability of the polymer particles containing the colorant in the ink. % Or more, and preferably 50% by mass or less, more preferably 40% by mass or less.
The mass ratio of the amount of the colorant to the amount of the water-insoluble polymer [colorant / water-insoluble polymer] is preferably from the viewpoint of improving the dispersion stability of the polymer particles containing the colorant in the ink and the aqueous medium. Is 50/50 or more, more preferably 60/40 or more, still more preferably 70/30 or more, and preferably 90/10 or less, more preferably 80/20 or less.

  There is no particular limitation on the method for dispersing the aqueous dispersion of polymer particles containing the colorant. It is preferable to control the volume average particle diameter of the polymer particles containing the colorant to a desired particle diameter by using a known kneader or disperser (for example, a high pressure homogenizer). By removing the organic solvent from the obtained dispersion by a method such as distillation, an aqueous dispersion of polymer particles containing a colorant can be obtained. Before the dispersion, it is preferable to filter the aqueous dispersion of polymer particles containing the colorant with a filter (for example, a wire mesh or a plastic mesh) in advance to remove coarse particles.

  The obtained aqueous dispersion of polymer particles containing the colorant is preferably filtered through a filter (for example, a wire net or a plastic mesh) to remove coarse particles. Further, from the viewpoint of improving the productivity and storage stability of the aqueous dispersion of the polymer particles containing the colorant, the polymer particles containing the colorant are subjected to a crosslinking treatment or optionally added to the aqueous ink described below. Various additives such as an organic solvent, an antiseptic agent and an antifungal agent may be added to the aqueous dispersion liquid of the polymer particles containing the colorant.

  The solid content concentration of the aqueous dispersion of the polymer particles containing the colorant, from the viewpoint of improving the productivity and storage stability of the aqueous dispersion, and from the viewpoint of improving the adhesiveness and hydrolysis resistance to the resin recording medium. From the above, preferably 5% by mass or more, more preferably 10% by mass or more, further preferably 15% by mass or more, and preferably 50% by mass or less, more preferably 40% by mass or less, further preferably 35% by mass. It is the following.

<Optional components of water-based ink>
The water-based ink of the present invention includes an organic solvent, a surfactant, a wetting agent, a penetrating agent, a dispersant, a viscosity adjusting agent, a defoaming agent, an antiseptic agent, an antifungal agent, a rust preventive agent, a pH adjusting agent, and an antioxidant. Various additives such as UV absorbers can be added.
Examples of the organic solvent include polyhydric alcohols, polyhydric alcohol alkyl ethers, polyhydric alcohol aryl ethers, cyclic carbonates, nitrogen-containing heterocyclic compounds, amides, amines and sulfur-containing compounds.

  As the polyhydric alcohol, ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, polypropylene glycol, 1,3-propanediol, 1,2-butanediol, 1,3- Butanediol, 2,3-butanediol, 1,4-butanediol, 3-methyl-1,3-butanediol, 1,5-pentanediol, 1,2-hexanediol, 1,6-hexanediol, 2 -Methyl-2,4-pentanediol, tetraethylene glycol, glycerin, 1,2,6-hexanetriol, 1,2,4-butanetriol, 1,2,3-butanetriol, 3-methyl-1,3 , 5-pentanetriol, 2-d Le-1,3-hexanediol, 2,2,4-trimethyl-1,3-pentanediol.

  As the polyhydric alcohol alkyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, triethylene glycol monomethyl ether, triethylene glycol monoisobutyl ether, tetraethylene glycol monomethyl ether , Propylene glycol monoethyl ether, dipropylene glycol monobutyl ether, dipropylene glycol monomethyl ether, tripropylene glycol monomethyl ether, tripropylene glycol monobutyl ether and the like.

Examples of the polyhydric alcohol aryl ether include ethylene glycol monophenyl ether and ethylene glycol monobenzyl ether.
Examples of the cyclic carbonate include ethylene carbonate and propylene carbonate.
Examples of the nitrogen-containing heterocyclic compound include N-methyl-2-pyrrolidone, N-hydroxyethyl-2-pyrrolidone, 2-pyrrolidone, 1,3-dimethylimidazolidinone and ε-caprolactam.
Examples of the amide include formamide, N-methylformamide, N, N-dimethylformamide and the like.
Examples of the amine include monoethanolamine, diethanolamine, triethanolamine, monoethylamine, diethylamine, triethylamine and the like.
Examples of the sulfur-containing compound include dimethyl sulfoxide, sulfolane, thiodiethanol and thiodiglycol.

These organic solvents may be used alone or in combination of two or more, but it is preferable to use two or more kinds in combination.
Among these, at least one type or two or more types selected from polyhydric alcohols, polyhydric alcohol alkyl ethers, and nitrogen-containing heterocyclic compounds are preferable, and diethylene glycol, propylene glycol, dipropylene glycol, 1,2-butanediol, 1 , 2-hexanediol, glycerin, diethylene glycol monomethyl ether, dipropylene glycol monomethyl ether, and 2-pyrrolidone are preferably used alone or in combination of two or more.

  The content of the organic solvent in the ink is preferably 5% by mass or more, more preferably 10% by mass or more, and preferably 40% by mass or less, more preferably from the viewpoint of improving the dispersion stability of the ink. Is 35% by mass or less.

Examples of the surfactant include nonionic surfactants, anionic surfactants, amphoteric surfactants, silicone-based surfactants and fluorine-based surfactants. The surfactant may be used as a wetting agent, a penetrating agent and a dispersant.
Examples of the nonionic surfactant include glycol ethers such as polyoxyethylene alkyl ether, acetylene glycol, polyoxyethylene alkylphenyl ether, polyoxyethylene alkyl ester, and polyoxyethylene sorbitan fatty acid ester.
Examples of the anionic surfactant include polyoxyethylene alkyl ether acetate, dodecylbenzene sulfonate, succinic acid ester sulfonate, lauryl salt, and salt of polyoxyethylene alkyl ether sulfate.

Examples of the amphoteric surfactant include lauryl aminopropionate, lauryl dimethyl betaine, stearyl dimethyl betaine, lauryl dihydroxyethyl betaine, lauryl dimethyl amine oxide, myristyl dimethyl amine oxide, stearyl dimethyl amine oxide, and dihydroxy ethyl lauryl amine oxide. Can be mentioned.
Examples of the silicone-based surfactant include polyester-modified silicone and polyether-modified silicone.
Examples of the fluorine-based surfactant include perfluoroalkyl sulfonic acid compounds, perfluoroalkyl carboxylic acid compounds, perfluoroalkyl phosphate ester compounds, perfluoroalkyl ethylene oxide adducts, and the like.
The surfactants may be used alone or in combination of two or more.

  Among these, at least one selected from nonionic surfactants and silicone-based surfactants is preferable, and at least one selected from glycol ether, acetylene glycol, polyester-modified silicone, and polyether-modified silicone is more preferable, and acetylene. At least one selected from glycol and polyoxyethylene alkyl ether is more preferable.

  The content of the surfactant in the ink is preferably 0.1% by mass or more, more preferably 0.3% by mass or more, and preferably 5% by mass, from the viewpoint of improving the dispersion stability of the ink. % Or less, more preferably 2% by mass or less.

Examples of the defoaming agent include silicone-based defoaming agents, polyether-based defoaming agents, and fatty acid ester-based defoaming agents.
Examples of the preservative and antifungal agent include 1,2-benzisothiazolin-3-one, sodium dehydroacetate, sodium sorbate, 2-pyridinethiol-1-oxide sodium, sodium benzoate, and sodium pentachlorophenol. Can be mentioned.
Examples of the rust preventive agent include acidic sulfite, sodium thiosulfate, ammonium thiodiglycolate, diisopropylammonium nitrite, pentaerythritol tetranitrate and the like.

  The pH adjusting agent is not particularly limited as long as it can adjust the pH to 7 or more without adversely affecting the ink to be prepared, and any substance can be used according to the purpose. For example, diethanolamine, Amines such as triethanolamine; hydroxides of alkali metals such as lithium hydroxide, sodium hydroxide, potassium hydroxide; carbonates of alkali metals such as lithium carbonate, sodium carbonate, potassium carbonate; ammonium hydroxide, quaternary Examples thereof include ammonium hydroxide.

Examples of antioxidants include phenolic antioxidants (including hindered phenolic antioxidants), amine antioxidants, sulfur antioxidants, phosphorus antioxidants, and the like.
Examples of the UV absorber include benzophenone-based UV absorbers, benzotriazole-based UV absorbers, salicylate-based UV absorbers, and the like.

<Water-based ink manufacturing method>
The water-based ink of the present invention is obtained, for example, by mixing an aqueous dispersion of the polyester resin particles and an aqueous dispersion containing a colorant, preferably the aqueous dispersion of the polyester resin particles, and the coloring. It is obtained by mixing with an aqueous dispersion of polymer particles containing an agent.
Here, the aqueous dispersion containing a colorant refers to a dispersion of colorant particles in which a colorant is dispersed in an aqueous medium, preferably the colorant and the aqueous medium, the surfactant and the like. In the presence of, it is preferably obtained by dispersion using a disperser.
Here, you may further mix at least 1 sort (s) of the above-mentioned arbitrary component. For mixing, for example, various stirring devices can be used.
The preferable contents of the polyester resin particles and the colorant in the water-based ink are as described above.

  The content of water contained in the water-based ink of the present invention is preferably 30% by mass or more, more preferably 40% by mass or more, and further preferably 50% by mass or more in the ink from the viewpoint of appropriately maintaining the viscosity of the ink. And preferably 90% by mass or less, more preferably 80% by mass or less, still more preferably 75% by mass or less.

[Inkjet recording method]
The water-based ink of the present invention can be used as an ink for inkjet recording. In a preferred embodiment of using the water-based ink of the present invention in an inkjet recording method, after the water-based ink of the present invention is attached to a resin-made recording medium by an ink jet recording method, a resin-made recording medium to which the water-based ink is attached is used. Heat to 40 ° C. or higher and 100 ° C. or lower.
The resin recording medium is preferably a recording medium such as a polyvinyl chloride (PVC) recording medium and a polyethylene terephthalate (PET) recording medium, more preferably a polyvinyl chloride (PVC) recording medium. It can be suitably used for the method of forming an image by adhering the water-based ink of the invention.

The water-based ink of the present invention can be used for both office printing and commercial and industrial printing of catalogs, leaflets, packages, labels and the like. It can be preferably used for resin-made recording media suitable for commercial or industrial labels or package printing, particularly PVC recording media.
A corona-treated base material may be used as the resin recording medium. The substrate preferably has a film shape.

  The inkjet recording method of the present invention can use a known inkjet recording device. Examples of the inkjet recording device include a thermal inkjet recording device and a piezo inkjet recording device. The water-based ink of the present invention is more preferably used as a piezo type water-based ink for inkjet recording.

Further, in the inkjet recording method of the present invention, after the water-based ink is attached to the resin-made recording medium, the resin-made recording medium to which the water-based ink is attached is heated to 40 ° C. or more and 100 ° C. or less. The resin constituting the polyester resin particles in the water-based ink diffuses on the printing surface of the resin-made recording medium, and can act as a fixing aid for the colorant when forming a coating film. Adhesion to a PVC recording medium and a PET recording medium, more preferably a PVC recording medium, can be further improved.
The heating temperature of the resin-made recording medium is preferably 50 ° C. or higher, from the viewpoint of improving the adhesion to the resin-made recording medium, preferably the PVC-made recording medium and the PET-made recording medium, more preferably the PVC-made recording medium. It is more preferably 60 ° C or higher, and preferably 90 ° C or lower, more preferably 85 ° C or lower.

  Physical properties in the following production examples, examples, and comparative examples were measured and evaluated by the following methods.

[Polyester acid value]
It was measured according to the neutralization titration method described in JIS K0070-1992. However, the measurement solvent was a mixed solvent of acetone and toluene [acetone: toluene = 1: 1 (volume ratio)].

[Softening point and glass transition temperature of polyester]
(1) Using a softening point flow tester “CFT-500D” (manufactured by Shimadzu Corporation), a load of 1.96 MPa was applied by a plunger while heating 1 g of a sample at a temperature rising rate of 6 ° C./min, and the diameter was increased. It was extruded from a nozzle having a length 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.
(2) Glass transition temperature Using a differential scanning calorimeter “Q100” (manufactured by TA Instruments Japan Co., Ltd.), 0.02 g of a sample was weighed in an aluminum pan and heated to 200 ° C. The sample for measurement was prepared by cooling from the temperature to 0 ° C. at a temperature decrease rate of 10 ° C./min. Then, the measurement sample was heated at a heating rate of 10 ° C./min to measure the amount of heat. Of the observed endothermic peaks, the temperature of the peak with the largest peak area is taken as the maximum endothermic peak temperature, and the extension line of the baseline below the maximum endothermic peak and the maximum slope from the rising part of the peak to the apex of the peak. The temperature at the point of intersection with the tangent line is indicated as the glass transition temperature of the sample.

[Volume Average Particle Diameter (D _V ) of Polyester Resin Particles and Polymer Particles Containing Colorant (Pigment-Containing Anionic Polymer Particles)]
(1) Measuring device: Zeta potential and particle size measuring system "ELSZ-2" (manufactured by Otsuka Electronics Co., Ltd.)
(2) Measurement condition: It was measured by the cumulant analysis method. The dispersion liquid diluted with water so that the concentration of the particles to be measured is about 5 × 10 ⁻³ mass% was put in a measurement cell, the temperature was 25 ° C., the angle between the incident light and the detector was 90 °, and the number of integration was 100 times. The refractive index of water (1.333) was input as the refractive index of the dispersion solvent for measurement.

[Solid content concentration of aqueous dispersion of polyester resin particles]
Using an infrared moisture meter "FD-230" (manufactured by Ketsuto Scientific Laboratory Co., Ltd.), a measurement sample of 5 g was dried at a temperature of 150 ° C., measurement mode 96 (monitoring time 2.5 minutes, variation range of moisture content 0.05%). ), And the water content (mass%) of the aqueous dispersion was measured. The solid content concentration was calculated according to the following formula.
Solid content concentration (mass%) = 100−water content (mass%)

[Weight average molecular weight of water-insoluble polymer (anionic polymer)]
Using the following measuring device and analytical column, gel permeation chromatography using N, N-dimethylformamide in which phosphoric acid and lithium bromide were dissolved at concentrations of 60 mmol / L and 50 mmol / L, respectively, as an eluent. It was measured by the method. The weight average molecular weights (Mw) of the samples were several types of monodisperse polystyrene (product name: "TSKgel standard polystyrene"; type names: "A-500", "A-2500", "F-1", "F-10". ]; All were manufactured by Tosoh Corporation) as standard samples and calculated based on a calibration curve prepared in advance. The sample was dissolved in N, N-dimethylformamide to give a solution having a solid content of 0.3% by mass.
<Measurement conditions>
Measuring device: "HLC-8120GPC" (manufactured by Tosoh Corporation)
Analytical column: "TSK-GEL α-M" x 2 (manufactured by Tosoh Corporation)
Column temperature: 40 ° C
Flow rate: 1 mL / min

[Solid Content Concentration of Aqueous Dispersion of Polymer Particles Containing Colorant (Pigment-Containing Anionic Polymer Particles)]
Into a 30 mL polypropylene container (inner diameter 40 mm, height 30 mm) was weighed out 10.0 g of sodium sulfate that had been constant-weighted in a desiccator, and then about 1.0 g of the sample was added and mixed. Then, the mixture was accurately weighed, maintained at 105 ° C. for 2 hours to remove volatile matter, and allowed to stand in a desiccator for 15 minutes, and then the mass after drying was measured. The solid content of the sample was obtained by subtracting the mass of sodium sulfate from the mass of the mixture after drying, and divided by the mass of the sample before drying to obtain the solid content concentration (mass%).

[Adhesion of water-based ink]
An inkjet printer "IPSiO GX 2500" (manufactured by Ricoh Co., Ltd., piezo method) was filled with an aqueous ink, and an A4 solid image was printed on a PVC film (product name: "Transparent PVC RE-137", manufactured by Mimaki Engineering Co., Ltd.). . A sample was prepared by drying for 10 minutes in a dryer at 80 ° C., and then allowing it to stand for 1 day in an environment room at room temperature of 25 ° C. and relative humidity of 50%. After that, a tape "Cellotape CT15" (registered trademark) (manufactured by Nichiban Co., Ltd.) having a length of 5 cm and a width of 15 mm was attached to the printed surface of the sample for 4 cm with a 1 cm margin left at a speed of 10 cm / s at an angle of 90 °. The tape was peeled off, and the remaining area of the coated surface of the sample was visually evaluated in the following 5 grades. The higher the score, the better the adhesion to PVC.
<Evaluation criteria>
No peeling or peeling, but peeling area less than 5%: 5 points Peeling area 5% or more and less than 25%: 4 points Peeling area 25% or more and less than 50%: 3 points Peeling area 50% or more and less than 75%: 2 points Peeling area 75% or more: 1 point

[Hydrolysis resistance of water-based ink]
A 5N aqueous sodium hydroxide solution was added dropwise to the water-based ink to adjust the pH to 8, and the sample was placed in a glass container having a volume of 20 mL and allowed to stand in a constant temperature bath set at 70 ° C. After 1 week, the sample was taken out of the thermostat and cooled to room temperature (25 ° C), and then the pH was measured to obtain the amount of change in pH (value obtained by subtracting the first pH 8 from the pH after 1 week at 70 ° C). When the polyester is hydrolyzed, the pH shifts to the acid side due to the acid component generated by the decomposition, and thus the hydrolyzability can be evaluated by determining the pH change amount. The smaller the pH change amount, the more the hydrolysis is suppressed, that is, the more excellent the hydrolysis resistance is.

[Production of polyester]
Production Example R1 (Production of Polyester A)
The interior of a four-necked flask with an internal volume of 10 L equipped with a nitrogen introduction tube, a dehydration tube, a stirrer, and a thermocouple was replaced with nitrogen to give polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl). ) 5250 g of propane, 1270 g of terephthalic acid, 1556 g of dodecenylsuccinic anhydride, and 40 g of tin di (2-ethylhexanoate) were added, the temperature was raised to 230 ° C. under stirring under a nitrogen atmosphere, and the flask was held for 6 hours, then, the flask was charged. The internal pressure was lowered and the pressure was maintained at -8.3 kPa (G) for 1 hour. Then, after cooling to 215 ° C. and returning to atmospheric pressure, 288 g of trimellitic anhydride was added, and after holding at 215 ° C. for 1 hour, the pressure inside the flask was lowered to the desired pressure of −8.3 kPa (G). Was reacted up to the softening point to obtain polyester A. The properties of Polyester A are shown in Table 1.

Production Example R2 (Production of Polyester B)
The interior of a four-necked flask with an internal volume of 10 L equipped with a nitrogen introduction tube, a dehydration tube, a stirrer, and a thermocouple was replaced with nitrogen to give polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl). ) 5250 g of propane, 1121 g of terephthalic acid, 1796 g of dodecenylsuccinic anhydride, and 40 g of tin di (2-ethylhexanoate) were added, and the temperature was raised to 230 ° C. with stirring under a nitrogen atmosphere, and after holding for 6 hours, the flask was used. The internal pressure was lowered and the pressure was maintained at -8.3 kPa (G) for 1 hour. Then, after cooling to 215 ° C. and returning to atmospheric pressure, 317 g of trimellitic acid anhydride was added, and after holding at 215 ° C. for 1 hour, the pressure inside the flask was lowered to the desired value of −8.3 kPa (G). Was reacted up to the softening point of to obtain polyester B. The properties of Polyester B are shown in Table 1.

Production Example R3 (Production of Polyester C)
The interior of a four-necked flask with an internal volume of 10 L equipped with a nitrogen introduction tube, a dehydration tube, a stirrer, and a thermocouple was replaced with nitrogen to give polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl). ) 5250 g of propane, 1494 g of terephthalic acid, 1197 g of dodecenylsuccinic anhydride, and 40 g of tin di (2-ethylhexanoate) were added, and the temperature was raised to 230 ° C. with stirring under a nitrogen atmosphere, and after holding for 7 hours, the flask was added. The internal pressure was lowered and the pressure was maintained at -8.3 kPa (G) for 1 hour. Then, after cooling to 215 ° C. and returning to atmospheric pressure, 346 g of trimellitic anhydride was added, and after holding at 215 ° C. for 2 hours, the pressure in the flask was lowered to the desired value of −8.3 kPa (G). Was reacted up to the softening point of to obtain polyester C. The properties of Polyester C are shown in Table 1.

Production Example R4 (Production of Polyester D)
The interior of a four-necked flask with an internal volume of 10 L equipped with a nitrogen introduction tube, a dehydration tube, a stirrer, and a thermocouple was replaced with nitrogen to give polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl). ) 3675 g of propane, 1463 g of polyoxyethylene (2.2) -2,2-bis (4-hydroxyphenyl) propane, 1270 g of terephthalic acid, 1556 g of dodecenylsuccinic anhydride, and 40 g of tin di (2-ethylhexanoate) were added. The temperature in the flask was raised to 230 ° C. with stirring under a nitrogen atmosphere and kept for 7 hours, then the pressure in the flask was lowered and kept at −8.3 kPa (G) for 1 hour. Then, after cooling to 215 ° C. and returning to atmospheric pressure, 288 g of trimellitic anhydride was added, and after holding at 215 ° C. for 1 hour, the pressure inside the flask was lowered to the desired pressure of −8.3 kPa (G). Was reacted up to the softening point of to obtain polyester D. The properties of Polyester D are shown in Table 1.

Production Example R5 (Production of Polyester E)
The interior of a four-necked flask with an internal volume of 10 L equipped with a nitrogen introduction tube, a dehydration tube, a stirrer, and a thermocouple was replaced with nitrogen to give polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl). ) 2625 g of propane, 2438 g of polyoxyethylene (2.2) -2,2-bis (4-hydroxyphenyl) propane, 1270 g of terephthalic acid, 1556 g of dodecenylsuccinic anhydride, and 40 g of tin di (2-ethylhexanoate) were added. The temperature was raised to 230 ° C. with stirring under a nitrogen atmosphere and kept for 8 hours, then the pressure in the flask was lowered and kept at −8.3 kPa (G) for 1 hour. Then, after cooling to 215 ° C. and returning to atmospheric pressure, 288 g of trimellitic anhydride was added, and after holding at 215 ° C. for 1 hour, the pressure inside the flask was lowered to the desired pressure of −8.3 kPa (G). Was reacted up to the softening point of to obtain polyester E. The properties of Polyester E are shown in Table 1.

Production Example R6 (Production of Polyester F)
The interior of a four-necked flask with an internal volume of 10 L equipped with a nitrogen introduction tube, a dehydration tube, a stirrer, and a thermocouple was replaced with nitrogen to give polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl). ) Propane 5250 g, terephthalic acid 1743 g, dodecenyl succinic anhydride 804 g, and di (2-ethylhexanoic acid) tin 40 g were added, and the mixture was heated to 230 ° C. with stirring under a nitrogen atmosphere and held for 6 hours. The internal pressure was lowered and the pressure was maintained at -8.3 kPa (G) for 1 hour. Then, after cooling to 215 ° C. and returning to atmospheric pressure, 346 g of trimellitic anhydride was added, and after holding at 215 ° C. for 1 hour, the pressure in the flask was lowered to the desired value of −8.3 kPa (G). Was reacted up to the softening point to obtain polyester F. The properties of Polyester F are shown in Table 1.

Production Example R7 (Production of Polyester G)
The interior of a four-necked flask with an internal volume of 10 L equipped with a nitrogen introduction tube, a dehydration tube, a stirrer, and a thermocouple was replaced with nitrogen to give polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl). ) Propane 5250 g, terephthalic acid 1494 g, dodecyl succinic anhydride 1206 g, and di (2-ethylhexanoic acid) tin 40 g were added, and the temperature was raised to 230 ° C. with stirring under a nitrogen atmosphere, and after holding for 7 hours, The pressure in the flask was lowered, and the pressure was kept at -8.3 kPa (G) for 1 hour. Then, after cooling to 215 ° C. and returning to atmospheric pressure, 346 g of trimellitic anhydride was added, and after holding at 215 ° C. for 1 hour, the pressure in the flask was lowered to the desired value of −8.3 kPa (G). Was reacted up to the softening point to obtain Polyester G. The properties of Polyester G are shown in Table 1.

Production Example R8 (Production of Polyester H)
The interior of a four-necked flask having an internal volume of 10 L equipped with a nitrogen introduction tube, a dehydration tube, a stirrer, and a thermocouple was replaced with nitrogen to give polyoxyethylene (2.2) -2,2-bis (4-hydroxyphenyl). ) Propane 4875 g, terephthalic acid 1270 g, dodecenyl succinic anhydride 1556 g, and di (2-ethylhexanoic acid) tin 40 g were charged, and the mixture was heated to 230 ° C. with stirring under a nitrogen atmosphere and held for 8 hours, and then the flask. The internal pressure was lowered and the pressure was maintained at -8.3 kPa (G) for 1 hour. Then, after cooling to 215 ° C. and returning to atmospheric pressure, 288 g of trimellitic anhydride was added, and after holding at 215 ° C. for 1 hour, the pressure inside the flask was lowered to the desired pressure of −8.3 kPa (G). Was reacted up to the softening point to obtain Polyester H. The properties of Polyester H are shown in Table 2.

Production Example R9 (Production of Polyester I)
The interior of a four-necked flask with an internal volume of 10 L equipped with a nitrogen introduction tube, a dehydration tube, a stirrer, and a thermocouple was replaced with nitrogen to give polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl). ) 5600 g of propane, 1594 g of terephthalic acid, 369 g of trimellitic acid anhydride, and 40 g of tin di (2-ethylhexanoate) were added, the temperature was raised to 230 ° C. with stirring under a nitrogen atmosphere, and after holding for 6 hours, The pressure in the flask was lowered, and the pressure was kept at -8.3 kPa (G) for 1 hour. Then, after cooling to 210 ° C. and returning to atmospheric pressure, 557 g of fumaric acid and 2 g of 4-tert-butylcatechol were added, and after maintaining at 210 ° C. for 5 hours, the pressure inside the flask was lowered to −8.3 kPa ( G) was reacted up to the desired softening point to obtain polyester I. The properties of Polyester I are shown in Table 2.

Production Example R10 (Production of Polyester J)
The interior of a four-necked flask with an internal volume of 10 L equipped with a nitrogen introduction tube, a dehydration tube, a stirrer, and a thermocouple was replaced with nitrogen to give polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl). ) Propane 5250 g, terephthalic acid 1494 g, dodecenyl succinic anhydride 1197 g, and di (2-ethylhexanoic acid) tin 40 g were added, and the mixture was heated to 230 ° C. with stirring under a nitrogen atmosphere and held for 6 hours. The internal pressure was lowered and the pressure was maintained at -8.3 kPa (G) for 1 hour. Then, after cooling to 210 ° C. and returning to atmospheric pressure, 348 g of fumaric acid and 1 g of 4-tert-butylcatechol were added, and after holding at 210 ° C. for 5 hours, the pressure in the flask was lowered to −8.3 kPa ( Polyester J was obtained by reacting to the desired softening point in G). The properties of Polyester J are shown in Table 2.

Production Example R11 (Production of Polyester K)
The interior of a four-necked flask with an internal volume of 10 L equipped with a nitrogen introduction tube, a dehydration tube, a stirrer, and a thermocouple was replaced with nitrogen to give polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl). ) 6160 g of propane, 2125 g of fumaric acid, 4 g of 4-tert-butylcatechol, and 40 g of di (2-ethylhexanoic acid) tin were added and heated to 210 ° C. over 5 hours while stirring under a nitrogen atmosphere, and 2 After the temperature was maintained, the pressure in the flask was lowered, and the reaction was carried out at -8.3 kPa (G) until the softening point reached 100 ° C to obtain polyester K. The properties of Polyester K are shown in Table 2.

[Production of aqueous dispersion of polyester resin particles]
Production Example D1 (Production of aqueous dispersion of polyester resin particles A)
150 g of polyester A was placed in a four-necked flask having an internal volume of 2 L equipped with a nitrogen introduction tube, a reflux condenser, a stirrer (“Three One Motor BL300” (manufactured by Shinto Kagaku Co., Ltd.)) and a thermocouple at 30 ° C. The resin was dissolved by mixing with 300 g of methyl ethyl ketone (MEK). Then, 24.4 g of a 5 mass% sodium hydroxide aqueous solution was added and stirred for 30 minutes to obtain an organic solvent-based slurry. Under stirring at 30 ° C., 426 g of deionized water was added dropwise at a rate of 20 mL / min. Then, the temperature was raised to 60 ° C., methyl ethyl ketone was distilled off under reduced pressure, and a part of water was further distilled off. After cooling to 25 ° C., the mixture was filtered through a 150-mesh wire net and the solid content concentration was adjusted to 30% by mass with deionized water to obtain an aqueous dispersion of polyester resin particles A. Table 3 shows the volume average particle diameter (D _V ) of the polyester resin particles A in the obtained aqueous dispersion.

Production Examples D2 to D11 (Production of Aqueous Dispersion of Polyester Resin Particles B to K)
In the same manner as in Production Example D1, except that the type of polyester, the addition amount of a 5% by mass sodium hydroxide aqueous solution, and the addition amount of deionized water in Production Example D1 were changed to those shown in Tables 3 and 4, An aqueous dispersion of polyester resin particles B to K was obtained. The volume average particle diameter (D _V ) of the polyester resin particles in the obtained aqueous dispersion is shown in Tables 3 and 4.

[Production of Aqueous Dispersion of Water-Insoluble Polymer (Anionic Polymer) Particles Containing Colorant (Pigment)]
Production Example X1 (Preparation of Aqueous Dispersion of Water-Insoluble Polymer Particles X1 Containing Colorant (Pigment))
Synthesis of Water-Insoluble Polymer (Anionic Polymer) In a four-necked flask with an internal volume of 3 L equipped with two dropping funnels, 399 g of benzyl methacrylate (manufactured by Wako Pure Chemical Industries, Ltd.) and 91 g of methacrylic acid (Wako Pure Chemical Industries, Ltd.) Manufactured), methoxy polyethylene glycol methacrylate (product name: "M-230G", manufactured by Shin-Nakamura Chemical Co., Ltd., average number of moles of oxyethylene group added: 23) 140 g, styrene macromonomer (product name: "AS-6S") Manufactured by Toagosei Co., Ltd., solid content: 50%) was mixed with 140 g to prepare a monomer mixture liquid (770 g). 15.75 g of methyl ethyl ketone, 0.350 g of a polymerization chain transfer agent (2-mercaptoethanol), and 10% by mass (77 g) of the monomer mixture solution were put in a reaction vessel and mixed, and nitrogen gas substitution was performed.
On the other hand, in the dropping funnel, 80% by mass (616 g) of the monomer mixture liquid, 2.45 g of the polymerization chain transfer agent, 173.25 g of methyl ethyl ketone and the polymerization initiator 2,2′-azobis (2,4-dimethylvaleronitrile). (Product name: "V-65", manufactured by Wako Pure Chemical Industries, Ltd.) A mixture of 5.6 g was added, and the mixed solution in the reaction vessel was heated to 75 ° C under a nitrogen atmosphere while stirring and added dropwise. The mixed solution in the funnel was added dropwise over 4.5 hours. Then, a mixture of the remaining 10% by mass (77 g) of the monomer mixture, 0.7 g of the polymerization chain transfer agent, 126 g of methyl ethyl ketone, and 1.4 g of the polymerization initiator was added at the second stage at 75 ° C. and 1.7. It dripped over time.
After the dropping was completed, 2.1 g of the above initiator was mixed, the temperature was raised to 80 ° C., and the mixture was stirred for 1.5 hours. A solution of the water-insoluble polymer (weight average molecular weight Mw of the water-insoluble polymer Mw: 26,000) was obtained by further performing the operation of mixing the above-mentioned initiator, raising the temperature and stirring the mixture twice.

(2) Production of aqueous dispersion of water-insoluble polymer (anionic polymer) particles containing a pigment (hereinafter, also referred to as "pigment-containing anionic polymer particles") In a container having an internal volume of 2 L, 20 g of the polymer obtained by drying the solution of the water-insoluble polymer obtained by the synthesis of the water-insoluble polymer (anionic polymer) under reduced pressure was dissolved in 62.8 g of methyl ethyl ketone, and 5N aqueous sodium hydroxide solution was added thereto. 01 g, 1.13 g of 25 mass% ammonia water, and 236.5 g of deionized water were added, and the mixture was stirred and mixed at 2,000 r / min for 15 minutes using a Disper blade at 10 to 15 ° C.
Subsequently, 45 g of magenta pigment: PV19 (product name: "Inkjet Magenta E5B02", manufactured by Clariant Japan Co., Ltd.) and 25 g of magenta pigment: PR122 (product name: "6111T", manufactured by Dainichiseika Kogyo Co., Ltd.) were added. The mixture was stirred and mixed for 3 hours at 7,000 r / min using a Disper blade at -15 ° C.
The obtained dispersion was filtered with 200 mesh and subjected to 20-pass dispersion treatment at a pressure of 150 MPa using a microfluidizer "M-110K" (manufactured by Microfluidics, high pressure homogenizer).
Methyl ethyl ketone was removed from the obtained dispersion liquid at 60 ° C. under reduced pressure, a part of water was further removed, and the mixture was centrifuged, and the liquid layer portion was filtered through a filter having a pore size of 5 μm (manufactured by Sartorius Stedim Biotech) to obtain a coarse particle. Particles were removed. Further, 80 g of this dispersion was mixed with 0.2 g of a preservative (product name: "Proxel XL2", manufactured by Abyssia) and 19.8 g of deionized water, and sterilized at 70 ° C for 1 hour, and then 25 The mixture was cooled to 0 ° C., and filtered with a filter having a pore size of 5 μm to obtain an aqueous dispersion of pigment-containing anionic polymer particles (solid content concentration: 20 mass%, volume average particle diameter (D _V ): 133 nm).

[Manufacture of water-based ink]
Examples 1 to 7 and Comparative Examples 1 to 4 (production of water-based inks A to K)
In a 100 mL screw tube, 20.0 parts by mass of propylene glycol (manufactured by Wako Pure Chemical Industries, Ltd.), 10.0 parts by mass of 1,2-butanediol (manufactured by Wako Pure Chemical Industries, Ltd.), wetting agent (product name: "Olfin E1010 "(Olfin is a registered trademark), acetylene glycol-based surfactant, manufactured by Nissin Chemical Industry Co., Ltd., 1.0 part by mass, and deionized water 26.6 parts by mass are mixed, and a magnetic stirrer is used to attain room temperature After stirring for 15 minutes, a mixed solution was obtained.
Next, 25.7 parts by mass of the aqueous dispersion of the pigment-containing anionic polymer particles obtained in Production Example X1 (4.0 parts by mass in terms of pigment content (in 100 parts by mass of the water-based ink)) was stirred with a magnetic stirrer. While mixing the whole amount of the mixed solution, 16.7 parts by mass of an aqueous dispersion of polyester resin particles shown in Tables 5 and 6 (5.0 parts by mass in terms of solid content (in 100 parts by mass of the water-based ink)) was dropped. The mixture was stirred and mixed while being dropped. Finally, it was filtered through a filter having a pore size of 1.2 μm (product name: “Minisart” (registered trademark), manufactured by Sartorius Stedim Biotech) to obtain an aqueous ink. The evaluation results of the obtained water-based inks A to K are shown in Tables 5 and 6.

From the results in Table 5, it can be seen that each of the water-based inks of Examples 1 to 7 is excellent in both adhesion to a PVC film and hydrolysis resistance.
On the other hand, from the results of Table 6, the water-based ink of Comparative Example 1 containing no propylene oxide adduct of bisphenol A as an alcohol component may be inferior in adhesion to the PVC film as compared with the water-based ink of each Example. Recognize.
Comparative Example 2 containing no succinic acid substituted with an alkyl group having 1 to 20 carbon atoms or an alkenyl group having 2 to 20 carbon atoms as a carboxylic acid component, and a polyvalent carboxylic acid having a valence of 3 or more as a carboxylic acid component Comparative Example 3 containing no succinic acid, succinic acid substituted with an alkyl group having 1 to 20 carbon atoms or an alkenyl group having 2 to 20 carbon atoms as a carboxylic acid component, and a trivalent or higher polyvalent carboxylic acid It can be seen that the water-based inks of Comparative Example 4, which do not contain any of them, are inferior in hydrolysis resistance to the water-based inks of the respective examples.

Claims (7)

An aqueous ink containing a colorant and polyester resin particles,
Polyester contained in the polyester resin particles, I polycondensate der alcohol component and carboxylic acid component, Ri acid value of the polyester is 5 mgKOH / g or more 30 mgKOH / g Der below,
As the alcohol component, a propylene oxide adduct of bisphenol A is contained in the alcohol component in an amount of 60 mol% or more and 100 mol% or less,
As the carboxylic acid component, succinic acid substituted with an alkyl group having 1 to 20 carbon atoms or an alkenyl group having 2 to 20 carbon atoms is contained in the carboxylic acid component in an amount of 25 mol% to 50 mol%, and further 3 An aqueous ink containing a polyvalent carboxylic acid having a valence of 3 or more.   The water-based ink according to claim 1, wherein the content of the trivalent or higher polycarboxylic acid in the carboxylic acid component is 4 mol% or more and 25 mol% or less.   The water-based ink according to claim 1, wherein the trivalent or higher polycarboxylic acid is trimellitic acid.   The water-based ink according to claim 1, wherein the succinic acid substituted with an alkyl group having 1 to 20 carbon atoms or an alkenyl group having 2 to 20 carbon atoms is dodecenylsuccinic acid.   The water-based ink according to claim 1, further comprising terephthalic acid as a carboxylic acid component.   After adhering the water-based ink according to any one of claims 1 to 5 to a resin-made recording medium by an inkjet recording method, the resin-made recording medium to which the water-based ink is adhered is heated to 40 ° C or more and 100 ° C or less Inkjet recording method.   The ink jet recording method according to claim 6, wherein the resin recording medium is a polyvinyl chloride recording medium.