JP2017088678A - Aqueous ink - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an aqueous ink excellent in adhesiveness to a resin made recording medium and alcohol resistance and an inkjet recording method.SOLUTION: There are provided [1] an aqueous ink containing a coloring agent and a polyester resin particle, wherein polyester contained in the polyester resin particle is polyester (A) which is a polycondensate of an alcohol component containing sterol and a carboxylic acid component and content of a constitutional unit derived from sterol is 2 mass% to 35 mass% and [2] an inkjet recording method including adhering the aqueous ink of [1] to a resin made recording medium by an inkjet recording method and then heating the resin made recording medium to which the aqueous ink adhered at 40°C to 100°C.SELECTED DRAWING: None

Description

  The present invention relates to an aqueous ink containing polyester resin particles and an ink jet recording method.

  In the field of commercial label printing used for product packaging printing and advertisement, etc., resin records such as PET (polyethylene terephthalate), PVC (polyvinyl chloride), PE (polyethylene), PP (polypropylene), NY (nylon) Conventionally, printing has been performed on a medium using solvent-based ink, UV curable ink, or the like. On the other hand, from the viewpoints of reducing environmental burden, energy saving, safety, etc., as a printing method using water-based ink, it is required to utilize an inkjet recording method or a flexographic printing method. In particular, the ink jet recording method is a recording method in which ink droplets are directly ejected and adhered to a recording member from very fine nozzles to obtain characters and images. Full colorization is easy and inexpensive. Because of the many advantages of using plain paper as a member and non-contact with the object to be printed, the spread is remarkable. Thus, an attempt has been made to utilize an ink jet recording method for the resin recording medium.

  In patent document 1, it is the water-based ink for inkjet recording containing a coloring agent and a polyester-type resin particle, Comprising: The polyester-type resin which comprises a polyester-type resin particle is a segment which consists of a polyester resin, and a segment which consists of an addition polymerization type resin. An aqueous inkjet recording ink containing a composite resin formed by covalent bonding and containing an acrylate ester having a specific carbon number alkyl group and a methacrylic acid ester having a specific carbon number alkyl group is described. It shows excellent adhesion and glossiness to resin recording media such as PET and PP.

Japanese Patent Laying-Open No. 2015-124353

Since resin recording media such as PET, PP, and PVC are non-water-absorbing or low-water-absorbing media, they are often used outdoors such as sign graphics represented by vehicle wrapping. Therefore, in addition to the adhesiveness of the ink to the resin recording medium, it can be adapted for outdoor use, and further has an alcohol resistance against a lower alcohol having 4 or less carbon atoms such as ethanol contained in a cleaning liquid used during cleaning. However, conventional inks such as the ink disclosed in Patent Document 1 have not reached a technical level that satisfies all these characteristics.
Accordingly, the present invention provides a water-based ink excellent in adhesion to a resin recording medium and alcohol resistance, and an ink jet recording method.

  As a result of intensive studies, the present inventors have found that the above problem can be solved by containing a specific amount of sterol as a constituent unit in the polyester resin particles.

That is, the present invention relates to [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 polyester (A) which is a polycondensate of an alcohol component containing sterol and a carboxylic acid component,
A water-based ink in which the content of a structural unit derived from sterol in the polyester (A) is 2% by mass or more and 35% by mass or less.
[2] Inkjet recording in which the water-based ink described in [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. Method.

  ADVANTAGE OF THE INVENTION According to this invention, the water-based ink which has the outstanding adhesiveness with respect to a resin-made recording medium, and alcohol resistance, and the inkjet recording method can be provided.

[Water-based ink]
The water-based ink of the present invention contains a colorant and polyester resin particles. The water-based ink is a polyester (A) in which the polyester contained in the polyester resin particles is a polycondensate of an alcohol component containing a sterol and a carboxylic acid component, and contains a sterol-derived structural unit in the polyester (A). The amount is 5% by mass or more and 35% by mass or less.

The reason why the water-based ink having such a configuration has excellent adhesion and alcohol resistance to a resin recording medium is not clear, but is considered as follows.
The water-based ink of the present invention contains a colorant and polyester resin particles. When the ink adheres to the recording medium during printing, the polyester contained in the polyester resin particles diffuses on the printing surface of the resin recording medium and acts as a fixing aid for the colorant. Here, the polyester is a polycondensate of an alcohol component containing a sterol and a carboxylic acid component. By using a specific amount of an alcohol having a sterol skeleton as a raw material monomer for polyester, a plurality of aliphatic rings are bonded to each other while maintaining the film properties exhibited by polyester and adhesion to a resin recording medium such as PET having polarity. In particular, since the hydrophobic group having a large and high planarity interacts strongly with a hydrophobic resin recording medium such as PP, it is considered that the adhesion to these recording media is improved. Further, since the polyester has a sterol skeleton, the rigidity is increased, so that the swelling of the resin film of the polyester protecting the printed surface with the alcohol solvent is suppressed, and the alcohol resistance is considered to be improved.
In this specification, “water-based ink” may be simply referred to as “ink”.

[Polyester resin particles]
The polyester resin particles in the present invention contain polyester (A) which is a polycondensate of an alcohol component containing sterol and a carboxylic acid component.

[Polyester (A)]
The polyester (A) is produced using an alcohol component containing sterol from the viewpoint of improving adhesion to a resin recording medium and alcohol resistance, and contains a sterol-derived structural unit in the polymer.

<Sterol>
Sterol is an alcohol having a cyclopentahydrophenanthrene skeleton.
Examples of sterols include cholesterol, lanosterol, dihydrocholesterol, cholestanol, coprostanol, epicoprosterol, epicoprostanol, 22-dehydrocholesterol, desmosterol, 24-methylenecholesterol, 24,25-dihydrolanosterol, Animal sterols such as norlanosterol, spinasterol, dihydroagnosterol, agnosterol, rophenol, latosterol; plant sterols (phytosterol) such as β-sitosterol, stigmasterol, brassicasterol, campesterol; ergosterol, etc. Examples include fungal sterols.
The sterol is preferably a monoalcohol.
Among these, animal sterols are preferable and cholesterol is more preferable from the viewpoint of improving adhesion to a resin recording medium and alcohol resistance.
The content of the structural unit derived from sterol in the polyester (A) is 2% by mass or more and 35% by mass or less, preferably 5% by mass from the viewpoint of improving the adhesion to a resin recording medium and the alcohol resistance. More preferably, it is 7% by mass or more, and preferably 30% by mass or less, more preferably 25% by mass or less, and further preferably 20% by mass or less.
When the content of the structural unit derived from sterol in the polyester (A) is within the above range, a water-based ink having excellent adhesion to a resin recording medium and alcohol resistance can be obtained.
Further, the content of sterol in the alcohol component which is a raw material monomer of the polyester (A) is preferably 2 mol% or more in the alcohol component from the viewpoint of improving the adhesion to the resin recording medium and the alcohol resistance. More preferably, it is 5 mol% or more, More preferably, it is 7 mol% or more, Preferably it is 40 mol% or less, More preferably, it is 35 mol% or less, More preferably, it is 25 mol% or less.

The volume average particle diameter (D _V ) of the polyester resin particles is preferably 20 nm or more, more preferably 50 nm or more, still more preferably 70 nm or more, from the viewpoint of improving adhesion to a resin recording medium and alcohol resistance. The thickness is preferably 80 nm or more, and preferably 1000 nm or less, more preferably 500 nm or less, still more preferably 400 nm or less, and still more preferably 300 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 the examples.

  The polyester (A) preferably has an acid group at the end of the molecular chain from the viewpoint of improving the dispersion stability of the resin particles in the aqueous medium. Examples of the acid group include a carboxy group, a sulfonic acid group, a phosphonic acid group, and a sulfinic acid group. Among these, a carboxy group is more preferable from the viewpoint of improving the dispersion stability of the resin particles in the aqueous medium.

As an alcohol component, in addition to sterol, a diol, a trihydric or higher polyhydric alcohol, and the like may be contained.
Examples of the diol include aliphatic diols having 2 to 12 carbon atoms in the main chain, aromatic diols, and alicyclic diols.
Examples of the aliphatic diol having 2 to 12 carbon atoms in the main chain include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, 1,8- Examples include octanediol, 1,9-nonanediol, 1,10-decanediol, and 1,12-dodecanediol.
Examples of the aromatic diol include an alkylene oxide adduct of bisphenol A.
The alkylene oxide adduct of bisphenol A is preferably a compound represented by the following general formula (I) from the viewpoint of improving adhesion to a resin recording medium and alcohol resistance.

In the general formula (I), OR ¹ and R ² O are all alkyleneoxy groups, preferably each independently an alkyleneoxy group having 1 to 4 carbon atoms, more preferably an ethyleneoxy group or propylene. An oxy group, more preferably a propyleneoxy group.
x and y correspond to the number of added moles of alkylene oxide. Furthermore, 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 is preferably 7 or less, more preferably 5 or less, and even more preferably 3 or less. .
Further, x OR ¹ and y R ² O may be the same or different from each other, but are preferably the same from the viewpoint of improving the adhesion to the resin recording medium. The alkylene oxide adduct of bisphenol A may be used alone or in combination of two or more. The alkylene oxide adduct of bisphenol A is preferably a propylene oxide adduct of bisphenol A or an ethylene oxide adduct of bisphenol A, and more preferably a propylene oxide adduct of bisphenol A.

  Examples of the alicyclic diol include cyclohexanediol, cyclohexanedimethanol, hydrogenated bisphenol A, and the like.

As the alcohol component, from the viewpoint of improving adhesion to a resin recording medium and alcohol resistance, an adduct of bisphenol A having 2 or 3 carbon oxides (average added mole number of 1 to 16), And hydrogenated bisphenol A, and from the viewpoint of improving adhesion to a resin recording medium and alcohol resistance, preferably a propylene oxide adduct of bisphenol A or an ethylene oxide adduct of bisphenol A, A propylene oxide adduct of bisphenol A is preferred.
The content of the alkylene oxide adduct of bisphenol A in the alcohol component, which is a raw material monomer of polyester, is preferably 50 mol% or more, more preferably from the viewpoint of improving adhesion to a resin recording medium and alcohol resistance. 65 mol% or more, more preferably 70 mol% or more, more preferably 75 mol% or more, more preferably 80 mol% or more, and preferably 98 mol% or less, more preferably 95 mol% or less, still more preferably Is 93 mol% or less.

  The said alcohol component can be used individually by 1 type or in combination of 2 or more types.

Examples of the carboxylic acid component include dicarboxylic acids, trivalent or higher polyvalent carboxylic acids, acid anhydrides thereof, and alkyl esters having 1 to 3 carbon atoms thereof. Among them, dicarboxylic acids are preferably included. More preferably, it further contains a trivalent or higher polyvalent carboxylic acid.
Dicarboxylic acids include 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, and terephthalic acid is preferable from the viewpoint of improving adhesion to a resin recording medium and alcohol resistance.
Examples of the aliphatic dicarboxylic acid include fumaric acid, adipic acid, sebacic acid, maleic acid, azelaic acid, succinic acid, an alkyl group having 1 to 20 carbon atoms, or a succinic acid substituted with an alkenyl group having 2 to 20 carbon atoms. Etc. Specific examples of the 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, octenyl succinic acid, and the like. Among these, from the viewpoint of improving adhesion to a resin recording medium and alcohol resistance, preferably, it is at least one selected from fumaric acid, adipic acid, sebacic acid, and dodecenyl succinic acid, and more preferably fumaric. Acid or adipic acid, more preferably fumaric acid.
Examples of the alicyclic dicarboxylic acid include cyclohexane dicarboxylic acid.
When the dicarboxylic acid is included, the content thereof is preferably 60 mol% or more, more preferably 70 mol% or more, more preferably 70 mol% or more in the carboxylic acid component from the viewpoint of improving adhesion to a resin recording medium and alcohol resistance. Preferably it is 80 mol% or more, More preferably, it is 85 mol% or more, and it is 100 mol% or less, Preferably it is 99 mol% or less, More preferably, it is 95 mol% or less, More preferably, it is 92 mol% or less.

The trivalent or higher polyvalent carboxylic acid is preferably a trivalent polyvalent carboxylic acid from the viewpoint of increasing the acid value while introducing a sterol-derived structural unit into the polyester.
Examples of the trivalent or higher polyvalent carboxylic acid include trimellitic acid, 2,5,7-naphthalenetricarboxylic acid, pyromellitic acid, and the like, from the viewpoint of improving adhesion to a resin recording medium and alcohol resistance. Trimellitic acid is preferred.
In the case of containing a trivalent or higher polyvalent carboxylic acid, the content thereof is preferably 1 mol% or more, more preferably in the carboxylic acid component, from the viewpoint of improving adhesion to a resin recording medium and alcohol resistance. It is 5 mol% or more, more preferably 8 mol% or more, and preferably 30 mol% or less, more preferably 20 mol% or less, still more preferably 15 mol% or less.

  Among these, it is preferable that aromatic dicarboxylic acid and aliphatic dicarboxylic acid having 4 to 8 carbon atoms are included from the viewpoint of improving adhesion to a resin recording medium and alcohol resistance, and aromatic dicarboxylic acid. And an aliphatic dicarboxylic acid having 4 to 8 carbon atoms and a trivalent or higher polyvalent carboxylic acid compound are more preferable, and fumaric acid, terephthalic acid, and trimellitic acid are more preferably used in combination.

  The said carboxylic acid component can be used individually by 1 type or in combination of 2 or more types.

  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 (A) is excellent in adhesion and scratch resistance to the resin recording medium. From the viewpoint of improving, it is preferably 0.65 or more, more preferably 0.80 or more, and preferably 1.2 or less, more preferably 1.1 or less.

  The glass transition temperature of the polyester (A) is preferably 25 ° C. or higher, more preferably 35 ° C. or higher, and still more preferably 50 ° C. or higher, from the viewpoint of improving adhesion to a resin recording medium and alcohol resistance. And preferably it is 95 degrees C or less, More preferably, it is 80 degrees C or less, More preferably, it is 75 degrees C or less, More preferably, it is 70 degrees C or less.

The softening point of the polyester (A) is preferably 70 ° C. or higher, more preferably 80 ° C. or higher, more preferably 90 ° C. or higher, from the viewpoint of improving adhesion to a resin recording medium and alcohol resistance. The temperature is preferably 165 ° C. or lower, more preferably 130 ° C. or lower, and still more preferably 110 ° C. or lower.
In addition, when using 2 or more types of polyester (A) in mixture, the glass transition temperature and softening point are the values obtained by the method of an Example description as a mixture of 2 or more types of polyester, respectively.

The acid value of the polyester (A) is preferably 5 mgKOH / g or more, more preferably 10 mgKOH / g or more, and further preferably 13 mgKOH / g or more, from the viewpoint of improving the dispersion stability of the resin particles in the aqueous medium. And, it is preferably 35 mgKOH / g or less, more preferably 30 mgKOH / g or less, still more preferably 25 mgKOH / g or less.
The glass transition temperature, softening point, and acid value of the polyester (A) are all obtained by appropriately adjusting the type of monomer used in the production of the polyester, the blending ratio, the polycondensation temperature, and the reaction time. be able to.
Polyester (A) may be used alone or in combination of two or more.

The polyester (A) can be produced by subjecting an alcohol component containing sterol 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 using an esterification catalyst, an esterification cocatalyst, and a polymerization inhibitor as necessary at a temperature of 120 ° C. or more and 250 ° C. or less. 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 bistriethanolamate 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, with respect to 100 parts by mass of the total amount of the alcohol component and the carboxylic acid component, and The amount is preferably 1.5 parts by mass or less, more preferably 1.0 part by mass or less.
Examples of esterification promoters include pyrogallol compounds such as pyrogallol, gallic acid, and gallic acid esters; benzophenone derivatives such as 2,3,4-trihydroxybenzophenone and 2,2 ′, 3,4-tetrahydroxybenzophenone; epigallocatechin And catechin derivatives such as epigallocatechin gallate, and gallic acid is preferred from the viewpoint of reactivity.
The use amount of the esterification cocatalyst is preferably 0.001 part by mass or more, more preferably 0.01 part by mass or more with respect to 100 parts by mass of the total amount of the alcohol component and the carboxylic acid component from the viewpoint of reactivity. Yes, and preferably 0.5 parts by mass or less, more preferably 0.2 parts by mass or less.
Moreover, a polymerization inhibitor can be used as needed. 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 0 with respect to 100 parts by mass of the total amount of the alcohol component and the carboxylic acid component. 0.5 parts by mass or less, more preferably 0.1 parts by mass or less.

  In the present invention, the polyester includes a polyester modified to such an extent that the characteristics are not substantially impaired. As the modified polyester, for example, a composite resin having a segment made of an addition polymerization resin, JP-A-11-133668, JP-A-10-239903, by the method described in JP-A-2015-124353 and the like. Examples thereof include polyesters grafted or blocked with phenol, urethane, epoxy, or the like by a method described in JP-A-8-20636, or a composite resin having two or more resin units including a polyester unit.

The polyester resin particles may contain a resin other than polyester, for example, a resin such as a styrene-acrylic copolymer, an epoxy resin, a polycarbonate, and a polyurethane as long as the effects of the present invention are not impaired.
In addition, the polyester resin particles may contain additives such as reinforcing fillers such as fibrous substances, antioxidants, anti-aging agents, and the like as optional components, as long as the effects of the present invention are not impaired.

  In the polyester resin particles, the content of the polyester (A) is preferably 60% by mass or more, more preferably 80% by mass or more, and still more preferably, from the viewpoint of improving adhesion to a resin recording medium and alcohol resistance. It is 90 mass% or more, More preferably, it is 98 mass% or more, More preferably, it is 100 mass%.

[Colorant]
In the present invention, the colorant means a pigment or a dye. The colorant may be fine particles that are 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 (acidic 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 a pigment and a hydrophobic dye is preferable, and a pigment is more preferable.

The pigment may be either an inorganic pigment or an organic pigment.
Examples of the inorganic pigment include carbon black and metal oxide. When used for black ink, carbon black is preferable.
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. A phthalocyanine pigment, more preferably copper phthalocyanine.
The hue is not particularly limited, and any chromatic pigment such as yellow, magenta, cyan, blue, red, orange, and green can be used.

  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. One or more types of products selected from Pigment Green are listed.

In the present invention, a self-dispersing pigment can also be used. Self-dispersing pigments are those in which one or more hydrophilic functional groups (anionic hydrophilic groups such as carboxy groups and sulfonic acid groups, or cationic hydrophilic groups such as quaternary ammonium groups) are directly or other atomic groups. It means an inorganic pigment or an organic pigment that can be dispersed in an aqueous medium without using a surfactant or a resin. Here, as other atomic groups, an alkanediyl group having 1 to 12 carbon atoms, a phenylene group, a naphthylene group, or the like can be given.
The above-mentioned pigments can be used singly or in combination of two or more in any ratio.

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

The content of the colorant is preferably 1% by mass or more, more preferably 2% by mass or more, and further preferably 3% by mass or more in the ink from the viewpoint of improving the dispersion stability and image density of the ink. Preferably, it is 25 mass% or less, More preferably, it is 10 mass% or less, More preferably, it is 5 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 20 in the ink, from the viewpoint of improving adhesion to the resin recording medium and alcohol resistance. / 80 or more, more preferably 30/70 or more, further preferably 40/60 or more, and preferably 80/20 or less, more preferably 70/30 or less, still more preferably 60/40 or less, still more preferably. 50/50 or less.

[Polymer particles containing colorant]
The colorant is preferably made into fine particles that are stable in the ink using a surfactant, a polymer, or the like. That is, the colorant is preferably used as a colorant dispersed with a polymer dispersant or a polymer particle containing a colorant, and improves the dispersion stability and image density of the ink, and the surface smoothness of the printed matter. From the viewpoint of improvement, it is more preferable to use as polymer particles containing a colorant.

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

For the polymer particles containing the colorant, it is preferable to use a water-insoluble polymer from the viewpoint of improving the water dispersibility of the polymer particles in the ink and the image density of the ink. Here, the “water-insoluble polymer” refers to a polymer that has been dried at 105 ° C. for 2 hours and has reached a constant weight and dissolved in 100 g of water at 25 ° C., and its dissolved amount is 10 g or less. The dissolved amount is preferably 5 g or less, more preferably 1 g or less. In the case of an anionic polymer, the dissolution amount is the dissolution amount when the anionic group of the polymer is neutralized 100% with sodium hydroxide.
Examples of water-insoluble polymers include polyesters, polyurethanes, and vinyl polymers. From the viewpoint of improving the storage stability of ink, it is preferably obtained by addition polymerization of vinyl monomers (vinyl compounds, vinylidene compounds, vinylene compounds). 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 ejection property of the ink.

The ionic monomer is preferably an anionic monomer from the viewpoint of improving 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, and 2-methacryloyloxymethyl succinic acid.
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 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 dispersion stability of the polymer particles containing the colorant in the ink. The content is preferably 8% by mass or more, and preferably 40% by mass or less, more preferably 30% by mass or less, and still more preferably 25% by mass or less.

Examples of the hydrophobic monomer include alkyl (meth) acrylates having an alkyl group having 1 to 22 carbon atoms, more preferably 6 to 18 carbon atoms; styrene monomers such as styrene, 2-methylstyrene, and divinylbenzene; benzyl ( Aromatic group-containing (meth) acrylates such as meth) acrylate and phenoxyethyl (meth) acrylate are exemplified, and styrene and benzyl (meth) acrylate are preferred. “(Meth) acrylate” indicates at least one selected from acrylate and methacrylate.
From the viewpoint of improving the dispersion stability of the polymer particles containing the 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, it is preferably 98% by mass or less, more preferably 80% by mass or less.

The vinyl polymer has a number average molecular weight of 500 or more and 100 having a polymerizable functional group such as a (meth) acryloyloxy group at one end from the viewpoint of improving dispersion stability of the polymer particles containing the colorant in the ink. , 000 or less macromer, and nonionic monomer having a polyoxyalkylene glycol chain.
The amount of the macromer and the nonionic monomer component is preferably 1% by mass or more, more preferably 5% by mass, respectively, 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 50% by mass or less, more preferably 40% by mass or less, still more preferably 30% by mass or less, and further preferably 20% by mass or less.

  The monomer component of a vinyl polymer can be used individually by 1 type or in combination of 2 or more types, respectively.

  The weight average molecular weight of the water-insoluble polymer is preferably 5,000 or more, more preferably from the viewpoint of improving the dispersion stability of the polymer particles containing the colorant in the ink and the image density of the ink. It is 10,000 or more, more preferably 20,000 or more, and preferably 500,000 or less, more preferably 400,000 or less, still more preferably 300,000 or less, and further preferably 200,000 or less. In addition, the measurement of a weight average molecular weight can be performed by the method as described in an Example.

The water-insoluble polymer is produced by copolymerizing a monomer mixture by a known polymerization method. A preferred example of the polymerization method is a solution polymerization method in which the monomer mixture is heated and polymerized together with a polymerization initiator, a polymerization chain transfer agent, or the like in a solvent.
After 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 distillation.

(Method for producing polymer particles containing colorant)
The polymer particles containing a colorant include, for example, a water-insoluble polymer, an organic solvent, a colorant, water, and, if necessary, a mixture containing a neutralizer, a surfactant, and the like, and a colorant. After the dispersion of polymer particles to be obtained is obtained, the organic solvent can be removed from the dispersion to produce an aqueous dispersion of polymer particles containing a colorant.

Although there is no restriction | limiting in the organic solvent in which a water-insoluble polymer is dissolved, C1-C3 aliphatic alcohol, C3-C5 ketones, ethers, esters, etc. are preferable, and ketones are more preferable, More preferred is methyl ethyl ketone. When a water-insoluble polymer is synthesized by a solution polymerization method, the solvent used in the polymerization may be used as it is.
When the water-insoluble polymer is an anionic polymer, an anionic group in the water-insoluble polymer may be neutralized using a neutralizing agent. When using a neutralizing agent, it is preferable to neutralize so that pH may be 7 or more and 11 or less. Examples of the neutralizing agent include bases such as lithium hydroxide, sodium hydroxide, potassium hydroxide, ammonia, and various amines. Further, the water-insoluble polymer may be neutralized in advance.

In the dispersion of polymer particles containing the colorant, the colorant is preferably 5% by mass or more, more preferably 10% 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 in 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 restriction | limiting in particular in the dispersion method of a dispersion liquid. It is preferable to control the volume average particle diameter of the polymer particles containing the colorant to a desired particle diameter using a known kneader, disperser or the like. By removing the organic solvent from the obtained dispersion by a known method, an aqueous dispersion of polymer particles containing a colorant can be obtained.

  The obtained aqueous dispersion of polymer particles containing the colorant is preferably filtered through a wire mesh or the like to remove coarse particles and the like. In addition, from the viewpoint of improving the productivity and storage stability of the aqueous dispersion, the polymer particles containing the colorant are subjected to a crosslinking treatment, or optionally added to an aqueous ink described later, an organic solvent, an antiseptic, an anti-corrosion agent. Various additives such as glazes may be added to the aqueous dispersion of polymer particles containing a colorant.

  The solid content concentration of the aqueous dispersion of polymer particles containing the colorant is from the viewpoint of improving the productivity and storage stability of the aqueous dispersion, and from the viewpoint of improving the adhesion to the resin recording medium and the alcohol resistance. , 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 45% by mass or less, still more preferably 40% by mass or less. More preferably, it is 35% by mass or less.

[Optional components of water-based ink]
The water-based ink of the present invention includes an organic solvent, a penetrating agent, a dispersant, a surfactant, a viscosity modifier, an antifoaming agent, an antiseptic, an antifungal agent, a rust inhibitor, a pH adjuster, an antioxidant, and an ultraviolet absorber. Various additives such as an agent can be added.
Examples of the organic solvent include polyhydric alcohol, polyhydric alcohol alkyl ether, polyhydric alcohol aryl ether, cyclic carbonate, nitrogen-containing heterocyclic compound, amide, amine, and sulfur-containing compound.

  Examples of the polyhydric alcohol include 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.

  Polyhydric alcohol alkyl ethers include 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, thiodiglycol and the like.

The organic solvent may be used alone or in combination of two or more, but preferably used in combination of two or more.
Among these, at least one or more 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, , 2-hexanediol, glycerin, diethylene glycol monomethyl ether, dipropylene glycol monomethyl ether, and 2-pyrrolidone are more preferable.

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

  Examples of the surfactant include nonionic surfactants, anionic surfactants, amphoteric surfactants, silicone surfactants, and fluorine surfactants.

Examples of the nonionic surfactant include glycol ethers such as acetylene glycol and polyoxyethylene alkyl ether; polyoxyethylene alkyl phenyl ether, polyoxyethylene alkyl ester, polyoxyethylene sorbitan fatty acid ester, and the like.
Examples of the anionic surfactant include polyoxyethylene alkyl ether acetate, dodecyl benzene sulfonate, oxalate sulfonate, laurate, polyoxyethylene alkyl ether sulfate salt, and the like.

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

  Among these, at least one selected from nonionic surfactants and silicone surfactants is preferable, at least one selected from glycol ethers, polyester-modified silicones, and polyether-modified silicones is more preferable, and glycol ethers are further included. Preferably, at least one selected from acetylene glycol and polyoxyethylene alkyl ether is more preferable.

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

Examples of the antifoaming agent include silicone-based antifoaming agents, polyether-based antifoaming agents, and fatty acid ester-based antifoaming agents.
Examples of the antiseptic and antifungal agent include 1,2-benzisothiazolin-3-one, sodium dehydroacetate, sodium sorbate, sodium 2-pyridinethiol-1-oxide, sodium benzoate, and sodium pentachlorophenol. Can be mentioned.
Examples of the rust preventive include acid sulfite, sodium thiosulfate, ammonium thiodiglycolate, diisopropylammonium nitrite, pentaerythritol tetranitrate and the like.
The pH adjuster is not particularly limited as long as the pH can be adjusted 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 An ammonium hydroxide etc. are mentioned.
Examples of the antioxidant include phenol antioxidants (including hindered phenol antioxidants), amine antioxidants, sulfur antioxidants, phosphorus antioxidants, and the like.
Examples of the UV absorber include benzophenone UV absorbers, benzotriazole UV absorbers, salicylate UV absorbers, and the like.

[Method for producing water-based ink]
The water-based ink of the present invention can be preferably produced by performing the following steps (1) to (3).
Step (1): Step of obtaining a mixture of a resin containing polyester (A), an organic solvent, and a basic compound Step (2): The mixture obtained in step (1) is mixed with an aqueous medium and emulsified to obtain a polyester. Step of obtaining an aqueous dispersion of resin particles Step (3): Step of obtaining an aqueous ink by mixing the aqueous dispersion of polyester resin particles obtained in step (2) and an aqueous dispersion containing a colorant.

[Step (1)]
In step (1), a resin containing polyester (A) is dissolved in an organic solvent to obtain an organic solvent solution containing polyester (A).
The viewpoint of improving the affinity of the resin containing polyester to the aqueous medium, improving the dispersion stability of the polyester resin particles in the aqueous dispersion, and the viewpoint of improving the adhesion and scratch resistance to the resin recording medium Therefore, it is preferable to use a basic aqueous solution.

  Examples of the organic solvent in step (1) include ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and diethyl ketone; ether solvents such as dibutyl ether, tetrahydrofuran, and dioxane; acetate esters such as ethyl acetate and isopropyl acetate. Solvent: Alkyl halide solvents such as dichloromethane and chloroform. Among these, from the viewpoint of easy removal from the mixed solution after addition of the aqueous medium, it is preferably at least one selected from ketone solvents and acetate solvents, and more preferably methyl ethyl ketone, ethyl acetate and acetic acid. At least one selected from isopropyl, more preferably methyl ethyl ketone.

  The mass ratio of the organic solvent to the resin in the polyester resin particles (organic solvent / resin) is preferably from the viewpoint of dissolving the resin and facilitating phase inversion to an aqueous medium, and improving the dispersion stability of the resin particles. 0.3 or more, more preferably 0.5 or more, further preferably 0.7 or more, and preferably 5.0 or less, more preferably 3.0 or less, still more preferably 2.0 or less, still more preferably Is 1.5 or less.

Examples of the basic compound in the step (1) include alkali metal hydroxides such as lithium hydroxide, sodium hydroxide, and potassium hydroxide, ammonia, trimethylamine, ethylamine, diethylamine, triethylamine, diethanolamine, triethanolamine, and tributylamine. And nitrogen-containing basic substances. Among these, sodium hydroxide or ammonia is preferable from the viewpoint of improving the dispersion stability of the polyester resin particles.
The use equivalent (mol%) of the basic compound with respect to the acid group of the resin is preferably 10 mol% or more, more preferably 50 mol% or more from the viewpoint of improving the dispersion stability of the polyester resin particles, and Preferably it is 150 mol% or less, More preferably, it is 120 mol% or less, More preferably, it is 100 mol% or less.
In addition, the use equivalent (mol%) of a neutralizing agent can be calculated | required by a following formula. When the equivalent of the neutralizer is 100 mol% or less, it is synonymous with the degree of neutralization. When the equivalent of the neutralizer exceeds 100 mol% in the following formula, In this case, the degree of neutralization of the resin is regarded as 100 mol%.
Equivalents of neutralizing agent (mol%) = [{added mass of neutralizing agent (g) / equivalent of neutralizing agent} / [{resin acid value (mgKOH / g) × resin mass (g)} / (56 × 1000)]] × 100

  In the step (1), the above optional components such as a surfactant and a colorant may be further mixed.

[Step (2)]
In step (2), the mixture obtained in step (1) and the aqueous medium are mixed and emulsified to obtain an aqueous dispersion of polyester resin particles.
In step (2), an aqueous medium is gradually added to the mixture to perform phase inversion and emulsification (phase inversion emulsification method).

As the aqueous medium in the step (2), those containing water as a main component are preferable. From the viewpoint of improving the dispersion stability of the polyester resin particle dispersion and reducing the environmental load, the content of water in the aqueous medium is The amount is preferably 80% by mass or more, more preferably 90% by mass or more, still more preferably 95% by mass or more, still more preferably 98% by mass or more, and further preferably 100% by mass. As water, deionized water, ion exchange water, and distilled water are preferably used.
As components other than water, an organic solvent that dissolves in water such as an alkyl alcohol having 1 to 5 carbon atoms; a dialkyl ketone having 3 to 5 carbon atoms such as acetone and methyl ethyl ketone; and a cyclic ether such as tetrahydrofuran is used.

In the step (2), the addition amount of the aqueous medium is preferably 100 parts by mass or more, more preferably 150 parts by mass or more, further with respect to 100 parts by mass of the resin, from the viewpoint of improving the dispersion stability of the polyester resin particles. The amount is preferably 200 parts by mass or more, and preferably 900 parts by mass or less, more preferably 500 parts by mass or less, and still more preferably 300 parts by mass or less.
The mass ratio of the aqueous medium to the organic solvent after addition of the total amount (aqueous medium / organic solvent) is preferably 40/60 or more, more preferably 50/50 or more, still more preferably 60/40 or more, and preferably Is 90/10 or less, more preferably 85/15 or less, and still more preferably 80/20 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 polyester resin particles. ° C or lower, more preferably 65 ° C or lower, still more preferably 50 ° C or lower.
From the viewpoint of improving the dispersion stability of the polyester resin particles and improving the adhesion to the resin recording medium and the alcohol resistance, the addition rate of the aqueous medium is 100 parts by mass of the resin until the phase inversion is completed. Is preferably 0.5 parts by weight or more, more preferably 1 part by weight or more, still more preferably 3 parts by weight or more, and preferably 50 parts by weight or less, more preferably Is 30 parts by mass / min or less, more preferably 20 parts by mass / min or less. There is no restriction | limiting in the addition rate of the aqueous medium after phase inversion.

You may have the process of removing an organic solvent from the aqueous dispersion obtained by phase inversion emulsification as needed after phase inversion emulsification.
The method for removing the organic solvent is not particularly limited, and any method can be used. However, since it is dissolved in water, it is preferably distilled. In addition, the organic solvent may not be completely removed and may remain in the aqueous dispersion. In this case, the remaining amount of the organic solvent is preferably 1% by mass or less, more preferably 0.5% by mass or less, and further preferably substantially 0% in the aqueous dispersion.

The solid content concentration of the aqueous dispersion of the obtained polyester resin particles is preferably 10% by mass or more from the viewpoint of improving the productivity of the ink, and improving the adhesion to the resin recording medium and the alcohol resistance. More preferably, it is 20 mass% or more, More preferably, it is 25 mass% or more, Preferably it is 50 mass% or less, More preferably, it is 45 mass% or less, More preferably, it is 40 mass% or less.
In addition, solid content is the total amount of non-volatile components, such as said arbitrary components, such as resin, surfactant and the coloring agent which can be added as needed.

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, and still more preferably, from the viewpoint of improving adhesion to a resin recording medium and alcohol resistance. Is 70 nm or more, more preferably 80 nm or more, and preferably 1000 nm or less, more preferably 500 nm or less, still more preferably 400 nm or less, still more preferably 300 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 the examples.

[Step (3)]
The aqueous dispersion containing the colorant in step (3) is preferably an aqueous dispersion containing polymer particles containing a colorant.
In step (3), in addition to the colorant, at least one of the aforementioned optional components may be further mixed. For the mixing, for example, various stirring devices can be used.

[Composition of water-based ink]
The content of the polyester resin particles contained in the water-based ink is preferably 1% by mass or more in the ink from the viewpoint of keeping the viscosity of the ink properly and improving the adhesion to the resin recording medium and the alcohol resistance. More preferably, it is 2% by mass or more, more preferably 3% by mass or more, and preferably 20% by mass or less, more preferably 15% by mass or less, still more preferably 10% by mass or less, and further preferably 7% by mass. It is as follows.
The content of the polyester (A) contained in the water-based ink is preferably 1% by mass in the ink from the viewpoint of maintaining the viscosity of the ink properly and improving the adhesion to the resin recording medium and the alcohol resistance. Above, more preferably 2% by mass or more, still more preferably 3% by mass or more, and preferably 20% by mass or less, more preferably 15% by mass or less, and further preferably 10% by mass or less.
The content of the sterol component contained in the water-based ink is preferably 0.02% by mass or more, more preferably 0.05% by mass in the ink, from the viewpoint of obtaining excellent adhesion to a polyolefin recording medium and scratch resistance. More preferably, it is 0.07% by mass or more, and preferably 7% by mass or less, more preferably 6% by mass or less, and still more preferably 5% by mass or less.
The water-based ink may contain resin particles other than the polyester resin particles, for example, acrylic resin particles, vinyl chloride resin particles, polyurethane resin particles, and the like as long as the effects of the present invention are not impaired. The content of the resin particles other than the polyester resin particles is preferably 0.5% by mass or less, more preferably 0.2% by mass or less in the total resin particles in the water-based ink.

  The content of water contained in the water-based ink is preferably 30% by mass or more, more preferably 40% by mass or more, and preferably 90% by mass or less in the ink from the viewpoint of keeping the viscosity of the ink properly. More preferably, it is 80 mass% or less, More preferably, it is 75 mass% or less.

[Inkjet recording method]
The aqueous ink of the present invention can be used as an ink for ink jet recording. As a preferred embodiment when the aqueous ink of the present invention is used in an ink jet recording method, the aqueous recording ink of the present invention is attached to a resin recording medium by an ink jet recording method, and then the resin recording medium to which the aqueous ink adheres is used. Heat to 40 ° C or higher and 100 ° C or lower. Among them, it is preferably used in a method for forming an image by attaching the water-based ink of the present invention to a polyolefin recording medium and a polyethylene terephthalate recording medium, more preferably a polyolefin recording medium.

The water-based ink of the present invention can be used for both office printing and commercial and industrial printing of catalogs, flyers, packages, labels and the like. It can be suitably used for polyolefin recording media and polyethylene terephthalate recording media suitable for commercial and industrial label or package printing.
Examples of the polyolefin recording medium include a polypropylene substrate and a polyethylene substrate. The polyolefin recording medium may be a corona-treated substrate. The substrate is preferably in the form of a film.
Generally available films include, for example, KAINAS KEE70CA (manufactured by Lintec Corporation, polyethylene), YUPO SG90 PAT1 (manufactured by Lintec Corporation, polypropylene), FOR, FOA (all of which are manufactured by Futamura Chemical Co., Ltd., polypropylene), Lumirror T60, Lumirror 75T60 (manufactured by Toray Industries, Inc., polyethylene terephthalate) and the like.

In the ink jet recording method of the present invention, a known ink jet recording apparatus can be used. Examples of the ink jet recording apparatus include a thermal ink jet recording apparatus and a piezo ink jet recording apparatus. The water-based ink of the present invention is more preferably used as a piezoelectric ink-jet recording ink.
In the present invention, it is preferable that after the water-based ink is attached to the resin recording medium, the resin 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 colorant fixing aid when forming a coating film. Adhesion and alcohol resistance can be further improved.
The heating temperature of the resin recording medium is preferably 50 ° C. or higher, more preferably 60 ° C. or higher, and preferably 90 ° C. or lower, from the viewpoint of improving adhesion to the resin recording medium and alcohol resistance. More preferably, it is 85 ° C. or lower.

  Hereinafter, the present invention will be described more specifically with reference to examples and the like. In the following examples and the like, each physical property was measured by the following method.

[Acid value of polyester]
It measured according to JIS K0070. However, the measurement solvent was a mixed solvent of acetone and toluene [acetone: toluene = 1: 1 (volume ratio)].

[Softening point of polyester]
Using a flow tester “CFT-500D” (manufactured by Shimadzu Corporation), a 1 g sample was heated at a heating rate of 6 ° C./min, a load of 1.96 MPa was applied by a plunger, a diameter of 1 mm, and a length of 1 mm. Extruded from the nozzle. The amount of plunger drop of the flow tester was plotted against the temperature, and the temperature at which half of the sample flowed out was taken as the softening point.

[Glass transition temperature of polyester]
Using a differential scanning calorimeter “Q-100” (manufactured by TA Instruments Japan Co., Ltd.), 0.02 g of a sample was weighed into an aluminum pan, heated to 200 ° C., and the temperature decreasing rate was 10 ° C. / It cooled to 0 degreeC by min and the sample for a measurement was prepared. Then, it heated up with the temperature increase rate of 10 degrees C / min, and measured the calorie | heat amount. Among the observed endothermic peaks, the peak temperature with the maximum peak area is taken as the maximum peak temperature of the endotherm, the extension of the baseline below the maximum peak temperature of the endotherm, and the maximum slope from the peak of the peak to the peak apex The temperature at the point of intersection with the tangent line indicating the glass transition temperature.

[Volume Average Particle Diameter (D _v ) of Polyester Resin Particles, 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 conditions: cumulant analysis method. A dispersion liquid diluted with water so that the concentration of the particles to be measured is about 5 × 10 ⁻³ mass% is put in a measurement cell, the temperature is 25 ° C., the angle between the incident light and the detector is 90 °, and the number of integration is 100 times. Then, the refractive index of water (1.333) was input as the refractive index of the dispersion solvent and measured.

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

[Weight average molecular weight of water-insoluble polymer (anionic polymer)]
Using the following measuring device and analytical column, gel permeation chromatography using a solution in which phosphoric acid and lithium bromide are dissolved in N, N-dimethylformamide at concentrations of 60 mmol / L and 50 mmol / L, respectively, as an eluent Measured by the method. The molecular weight (Mw, Mn) of the sample is several types of monodisperse polystyrene (product name: “TSKgel standard polystyrene”; type names: “A-500”, “A-2500”, “F-1”, “F-10”). “All of them were manufactured by Tosoh Corporation) as a standard sample 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)]
In a 30 mL polypropylene container (inner diameter 40 mm, height 30 mm), weigh 10.0 g of sodium sulfate constant in a desiccator. The mixture was maintained at 105 ° C. for 2 hours to remove volatile matter, and further left in a desiccator for 15 minutes to measure the mass. The mass of the sample after removing the volatile matter was taken as the solid content and divided by the mass of the added sample to obtain the solid content concentration.

[Evaluation of adhesion]
An inkjet printer “IPSiO GX 2500” (Ricoh Co., Ltd., Piezo Method) is filled with water-based ink, and a biaxially stretched PET film “Lumirror 75T60” (manufactured by Toray Industries, Inc.) and a corona-treated PP film “FOR-15” ( A4 solid image was printed on (Futamura Chemical Co., Ltd.). The sample was dried for 10 minutes with a dryer at 80 ° C., and allowed to stand for 1 day in an environment room at room temperature of 25 ° C. and relative humidity of 50% to prepare a sample. After that, a tape “Cello Tape CT15” (registered trademark) (made by Nichiban Co., Ltd.) having a length of 5 cm and a width of 15 mm is pasted on the printed surface of the sample by 4 cm, leaving a 1 cm margin, and an angle of 90 ° and a speed of 10 cm / sec. The tape was peeled off, and the remaining area of the coated surface of the sample was visually evaluated in the following five stages. The higher the score, the better the adhesion.
<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 but less than 50%: 3 points peeling area 50% or more but less than 75%: 2 points Peel area 75% or more: 1 point

[Evaluation of alcohol resistance]
An inkjet printer “IPSiO GX 2500” (Ricoh Co., Ltd., Piezo Method) was filled with water-based ink, and an A4 solid image was printed on a biaxially stretched PET film “Lumirror 75T60” (Toray Industries, Inc.). The sample was dried for 10 minutes with a dryer at 80 ° C., and allowed to stand for 1 day in an environment room at room temperature of 25 ° C. and relative humidity of 50% to prepare a sample. Thereafter, with a cotton swab impregnated with an aqueous solution of ethanol whose concentration was adjusted every 10% by mass in the range of 0 to 100% by mass, the coated surface of the sample was applied as little as possible with a width of 2 to 3 cm. The coating surface was rubbed so as to stroke 10 times at a speed of 1 reciprocation per second. The state of the coated surface was visually evaluated, and the highest alcohol concentration at which changes such as scratches, peeling, and cloudiness were not observed before and after rubbing was used as an index of alcohol resistance. The higher the concentration, the better the alcohol resistance.

Production Example R1 (Production of Polyester A)
The inside of a four-necked flask equipped with a nitrogen introduction tube, a dehydration tube, a stirrer, and a thermocouple was replaced with nitrogen, and 4883 g of polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane, 600 g of cholesterol, 1801 g of terephthalic acid, 40 g of di (2-ethylhexanoic acid) tin, and 5 g of gallic acid were added, heated to 230 ° C. with stirring in a nitrogen atmosphere, and held for 8 hours. And held at 8.3 kPa for 1 hour. Then, after cooling to 210 ° C. and returning to atmospheric pressure, 539 g of fumaric acid and 1 g of 4-tert-butylcatechol were added and held at 210 ° C. for 4 hours, and then the pressure in the flask was lowered at 8.3 kPa. The polyester A was obtained by further holding for 4 hours. The properties of polyester A are shown in Table 1.

Production Example R2 (Production of Polyester B)
The inside of a four-necked flask equipped with a nitrogen introduction tube, a dehydration tube, a stirrer, and a thermocouple was purged with nitrogen, and 4340 g of polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane, Cholesterol 1200 g, terephthalic acid 1801 g, di (2-ethylhexanoic acid) tin 40 g, and gallic acid 5 g were added, heated to 230 ° C. with stirring in a nitrogen atmosphere, held for 8 hours, and then the pressure in the flask And held at 8.3 kPa for 1 hour. Then, after cooling to 210 ° C. and returning to atmospheric pressure, 450 g of fumaric acid and 1 g of 4-tert-butylcatechol were added and held at 210 ° C. for 4 hours, and then the pressure in the flask was lowered at 8.3 kPa. Further, it was held for 4 hours to obtain polyester B. The properties of polyester B are shown in Table 1.

Production Example R3 (Production of Polyester C)
The inside of a four-necked flask equipped with a nitrogen introduction tube, a dehydration tube, a stirrer, and a thermocouple was purged with nitrogen, and 4851 g of polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane, Cholesterol (596 g), terephthalic acid (1789 g), di (2-ethylhexanoic acid) tin (40 g), and gallic acid (5 g) were added, and the temperature in the flask was raised to 230 ° C. with stirring in a nitrogen atmosphere for 8 hours. And held at 8.3 kPa for 1 hour. Then, after cooling to 210 ° C. and returning to atmospheric pressure, 268 g of fumaric acid, 296 g of trimellitic anhydride, and 1 g of 4-tert-butylcatechol were added and held at 210 ° C. for 4 hours, and then the pressure in the flask was lowered. For 8 hours at 8.3 kPa to obtain polyester C. The properties of Polyester C are shown in Table 1.

Production Example R4 (Production of Polyester D)
The inside of a four-necked flask equipped with a nitrogen introduction tube, a dehydration tube, a stirrer, and a thermocouple was replaced with nitrogen, and 4312 g of polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane, 1192 g of cholesterol, 1789 g of terephthalic acid, 40 g of di (2-ethylhexanoic acid) tin, and 5 g of gallic acid were added, heated to 230 ° C. with stirring in a nitrogen atmosphere, held for 8 hours, and then the pressure in the flask And held at 8.3 kPa for 1 hour. Then, after cooling to 210 ° C. and returning to atmospheric pressure, 197 g of fumaric acid, 266 g of trimellitic anhydride, and 1 g of 4-tert-butylcatechol were added and held at 210 ° C. for 3 hours, and then the pressure in the flask was lowered. The polyester D was obtained by further holding at 8.3 kPa for 4 hours. The properties of polyester D are shown in Table 1.

Production Example R5 (Production of Polyester E)
The inside of a four-necked flask equipped with a nitrogen introduction tube, a dehydration tube, a stirrer, and a thermocouple was replaced with nitrogen, and 3773 g of polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane, Cholesterol 1788 g, terephthalic acid 1789 g, di (2-ethylhexanoic acid) tin 40 g, and gallic acid 5 g were added, heated to 230 ° C. with stirring in a nitrogen atmosphere, held for 8 hours, and then the pressure in the flask And held at 8.3 kPa for 1 hour. Then, after cooling to 210 ° C. and returning to atmospheric pressure, 125 g of fumaric acid, 266 g of trimellitic anhydride and 1 g of 4-tert-butylcatechol were added and held at 210 ° C. for 3 hours, and then the pressure in the flask was lowered. For 8 hours at 8.3 kPa to obtain polyester E. Properties of polyester E are shown in Table 1.

Production Example R6 (Production of Polyester F)
The inside of a four-necked flask equipped with a nitrogen introduction tube, a dehydration tube, a stirrer, and a thermocouple was replaced with nitrogen, and 2713 g of polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane, Cholesterol 2999 g, terephthalic acid 1801 g, di (2-ethylhexanoic acid) tin 40 g, and gallic acid 5 g were added, heated to 230 ° C. with stirring in a nitrogen atmosphere, held for 7 hours, and then the pressure in the flask And held at 8.3 kPa for 1 hour. Then, after cooling to 210 ° C. and returning to atmospheric pressure, 238 g of trimellitic anhydride was added and held at 210 ° C. for 3 hours, then the pressure in the flask was lowered and held at 8.3 kPa for another 2 hours. Polyester F was obtained. The characteristics of polyester F are shown in Table 1.

Production Example R7 (Production of Polyester G)
The inside of the four-necked flask equipped with a nitrogen introduction tube, a dehydration tube, a stirrer, and a thermocouple was replaced with nitrogen, and 5460 g of polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane, 2201 g of terephthalic acid, 40 g of di (2-ethylhexanoic acid) tin and 5 g of gallic acid were added, and the temperature was raised to 230 ° C. with stirring in a nitrogen atmosphere and maintained for 8 hours. The polyester G was obtained by holding at 8.3 kPa for 4 hours. The properties of polyester G are shown in Table 1.

Production Example D1 (Production of aqueous dispersion of polyester resin particles A)
A four-necked flask equipped with a nitrogen inlet tube, a reflux condenser, a stirrer (“Three-One Motor BL300” (manufactured by Shinto Kagaku Co., Ltd.)) and a thermocouple is charged with 200 g of polyester A, and methyl ethyl ketone (MEK) at 30 ° C. The resin was dissolved by mixing with 200 g. Subsequently, 35.9 g of 5 mass% sodium hydroxide aqueous solution was added, and it stirred for 30 minutes, and obtained the organic-solvent type slurry. 467 g of deionized water was added dropwise at 30 ° C. with stirring at a rate of 20 mL / min. Then, after raising the temperature to 60 ° C., methyl ethyl ketone was distilled off while gradually reducing the pressure to 80 kPa to 30 kPa, and a part of water was further distilled off. After cooling to 25 ° C., the mixture was filtered through a 150 mesh wire net, the solid content concentration was adjusted to 30% by mass with deionized water, and an aqueous dispersion of polyester resin particles A was obtained. Table 2 shows the characteristics of the polyester resin particles A in the obtained aqueous dispersion.

Production Examples D2 to D7 (Production of aqueous dispersion of polyester resin particles B to G)
In Production Example D1, the same as Production Example D1, except that the type and amount of polyester, the amount of methyl ethyl ketone, the addition amount of 5 mass% aqueous sodium hydroxide, and the addition amount of deionized water were changed to those shown in Table 2. Thus, an aqueous dispersion of polyester resin particles B to G was obtained. Table 2 shows the characteristics of the polyester resin particles in the obtained aqueous dispersion.

Production Example C1 (Preparation of aqueous dispersion of water-insoluble polymer particles C1 containing a colorant (pigment))
(1) Synthesis of water-insoluble polymer (anionic polymer) 399 g of benzyl methacrylate (manufactured by Wako Pure Chemical Industries, Ltd.), 91 g of methacrylic acid (manufactured by Wako Pure Chemical Industries, Ltd.), methoxypolyethylene glycol methacrylate (product name: “M- 230G ", manufactured by Shin-Nakamura Chemical Co., Ltd., average added mole number of oxyethylene group: 23) 140 g, styrene macromonomer (product name:" AS-6S ", manufactured by Toagosei Co., Ltd., solid content: 50%) 140 g Were mixed to prepare a monomer mixture (770 g). In a reaction vessel, 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 were mixed and subjected to nitrogen gas replacement.
Meanwhile, 80% by mass (616 g) of the monomer mixture, 2.45 g of the polymerization chain transfer agent, 173.25 g of methyl ethyl ketone, and a polymerization initiator 2,2′-azobis (2,4-dimethylvaleronitrile) are added to the dropping funnel. (Product name: “V-65”, manufactured by Wako Pure Chemical Industries, Ltd.) 5.6 g was added, and the mixture was heated to 75 ° C. while stirring the mixed solution in the reaction vessel under a nitrogen atmosphere. The mixed solution in the funnel was added dropwise over 4.5 hours. Thereafter, 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 dropwise at 75 ° C. and 1.7 ° C. It was added dropwise over time.
After completion of dropping, 2.1 g of the initiator was mixed, heated to 80 ° C., and stirred for 1.5 hours. This initiator was mixed, heated and stirred twice to obtain a polymer solution (polymer weight average molecular weight: 26,000).

(2) Production of aqueous dispersion of pigment-containing polymer particles (pigment-containing anionic polymer particles) Obtained by drying under reduced pressure the polymer solution obtained by the synthesis of water-insoluble polymer (anionic polymer) of (1) above. 20 g of the obtained polymer was dissolved in 62.8 g of methyl ethyl ketone, and 5.01 g of 5N sodium hydroxide aqueous solution, 1.13 g of 25 mass% aqueous ammonia and 236.5 g of deionized water were added thereto, The mixture was stirred and mixed at 2,000 r / min for 15 minutes using a disper blade.
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 Dainichi Seika Kogyo Co., Ltd.) were added. The mixture was stirred and mixed at 7,000 r / min for 3 hours at -15 ° C. using a disper blade. The obtained dispersion was filtered through 200 mesh and subjected to a 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 at 60 ° C. under reduced pressure, a part of water was further removed, and the mixture was centrifuged. Particles were removed. Further, 80 g of this dispersion was mixed with 0.2 g of a preservative (product name: “Proxel XL2”, manufactured by Avicia) and 19.8 g of deionized water, and sterilized at 70 ° C. for 1 hour. After cooling to 0 ° C. and filtering with a filter having a pore size of 5 μm, an aqueous dispersion (solid content concentration: 20% by mass, volume average particle size (D _V ) of pigment-containing polymer particles (pigment-containing anionic polymer particles) is obtained. ): 133 nm).

Examples 1 to 5, Comparative Examples 1 and 2 (Production of water-based ink)
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 (Wako Pure Chemical Industries, Ltd.), a wetting agent (product name: “Orphine” E1010 "(Olfin is a registered trademark), active ingredient: acetylene glycol surfactant, manufactured by Nissin Chemical Industry Co., Ltd. (1.0 part by mass) and deionized water (26.6 parts by mass) were mixed, and a magnetic stirrer was added. And stirred for 15 minutes at room temperature to obtain a mixed solution.
Next, 25.7 parts by mass of an aqueous dispersion of pigment-containing anionic polymer particles obtained in Production Example C1 (4.0 parts by mass in terms of pigment content (in 100 parts by mass of aqueous ink)) was stirred with a magnetic stirrer. While mixing the total amount of the mixed solution, 16.7 parts by weight of an aqueous dispersion of polyester resin particles shown in Table 3 (5.0 parts by weight in terms of solid content (in 100 parts by weight of aqueous ink)) was added dropwise with a dropper. While stirring, the mixture was mixed. Finally, the mixture was filtered with a filter having a pore diameter of 1.2 μm (product name: “Minisalto” (registered trademark), manufactured by Sartorius Stedim Biotech) to obtain a water-based ink. Table 3 shows the evaluation results of the obtained water-based ink.

  From the results of Table 3, the water-based inks of Examples 1 to 5 using polyester resin particles containing cholesterol-derived components are Comparative Example 1 having a high cholesterol content, and a water-based ink that does not contain cholesterol-derived components. It can be seen that the water-based ink of Comparative Example 2 is superior in adhesion to PP and PET media and in alcohol resistance of the printed matter.

Claims (5)

A water-based ink containing a colorant and polyester resin particles,
The polyester contained in the polyester resin particles is a polyester (A) which is a polycondensate of an alcohol component containing sterol and a carboxylic acid component,
A water-based ink in which the content of a structural unit derived from sterol in the polyester (A) is 2% by mass or more and 35% by mass or less.   2. The water-based ink according to claim 1, wherein a trivalent or higher polyvalent carboxylic acid is contained in an amount of 5 mol% to 30 mol% in the carboxylic acid component which is a raw material monomer of the polyester (A).   The water-based ink according to claim 1 or 2, wherein the sterol is cholesterol.   An ink jet in which the water-based ink according to any one of claims 1 to 3 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 higher and 100 ° C or lower. Recording method.   The inkjet recording method according to claim 4, wherein the resin recording medium is a polyolefin recording medium.