JP6457343B2 - Water-based ink - Google Patents

Description

  The present invention relates to a water-based ink containing polyester resin particles and a method for producing the same.

  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), etc. 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, a white color material and a polyester resin are used as an ink-jet white ink capable of recording an excellent image in which at least one of cracking, wear resistance, and adhesion is solved. A white ink for inkjet recording is described, which contains a first resin, a second resin made of at least one of a fluorene resin and a styrene acrylic resin, and a third resin made of a polyolefin wax.
Patent Document 2 includes a polymer particle A containing a colorant and a polyolefin component and subjected to a modification treatment selected from chlorination modification, acrylic modification, and maleic anhydride modification, and has a different structure portion from the polymer particle A. An ink recording method comprising an ink application step of applying an ink composition containing polymer particles B onto a recording substrate, which is an aggregate of non-absorbing or low-absorbing fiber materials, by an ink jet method. It is described that an image having excellent adhesion and scratch resistance to an aggregate of absorbent or low-absorbent fiber materials (such as a nonwoven fabric formed of resin fibers) can be obtained.

JP2013-177526A JP 2013-193324 A

According to the ink for ink jet recording described in Patent Document 1 or the like, when a highly polar resin such as PET is used for a recording medium, high adhesion and scratch resistance can be easily obtained, but PE, PP, etc. When the above polyolefin was used for a recording medium, there was a problem that sufficient adhesion and scratch resistance could not be obtained.
Moreover, the effect described in Patent Document 2 is still insufficient.
Accordingly, the present invention provides a water-based ink having excellent adhesion and scratch resistance to a polyolefin recording medium and a method for producing the same.

  As a result of intensive studies, the present inventors have found that the above problem can be solved by including a specific amount of polyolefin in the polyester resin particles.

That is, the present invention relates to [1] to [3].
[1] A water-based ink containing a colorant and polyester resin particles,
A water-based ink in which the polyester resin particles contain polyester and polyolefin, and the mass ratio of polyester to polyolefin (polyester / polyolefin) in the polyester resin particles is from 65/35 to 99/1.
[2] A method for producing a water-based ink, comprising the following steps (1) to (3).
Step (1): Step of obtaining a mixture of polyester / polyolefin, organic solvent, and basic compound having a mass ratio (polyester / polyolefin) of 65/35 to 99/1 Step (2): obtained in step (1) A step of mixing and emulsifying the mixture with an aqueous medium to obtain an aqueous dispersion of polyester resin particles Step (3): An aqueous dispersion of polyester resin particles obtained in Step (2) and an aqueous dispersion containing a colorant Step 3 of mixing aqueous solution to obtain water-based ink [3] After the water-based ink described in [1] is attached to a polyolefin recording medium by an ink jet recording method, a polyolefin recording medium having the water-based ink attached thereto is obtained. An ink jet recording method in which heating is performed at a temperature of not less than 100 ° C and not more than 100 ° C.

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

[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 resin particles include polyester and polyolefin, and the mass ratio of polyester to polyolefin (polyester / polyolefin) in the polyester resin particles is from 65/35 to 99/1.
The reason why the water-based ink having such a configuration has excellent adhesion and scratch resistance to a polyolefin recording medium is not clear, but is considered as follows.
Polyester resin particles blended in water-based inks form a film on a recording medium during printing for highly polar resins such as PET, and the adhesion of the colorant to the non-absorbent resin recording medium and its abrasion resistance However, since polyester has a relatively high polarity with respect to recording media with higher hydrophobicity such as polyolefin, the adhesion tends to be inferior.
In the water-based ink of the present invention, the polyolefin is premixed with the polyester to form resin particles, whereby the polyolefin is surrounded by the highly polar polyester and can be blended in the water-based ink. Furthermore, it is considered that the polyolefin undergoes fine phase separation on the coating film during printing, and sufficient adhesion to the polyolefin recording medium is expressed with a small amount of the polyester, so that the polyester covers this. Therefore, it is considered that the film performance excellent in scratch resistance is exhibited.
In this specification, “water-based ink” may be simply referred to as “ink”.

[Polyester resin particles]
The polyester resin particles in the present invention include polyolefin and polyester. The polyester resin particles preferably include a polyolefin. The polyolefin and the polyester are preferably at least partially compatible. The polyester resin particles are preferably obtained by dissolving or melting polyolefin and polyester.

  The total content of the polyester and the polyolefin in the polyester resin particles is preferably 90% by mass or more, more preferably 95% by mass or more, from the viewpoint of obtaining excellent adhesion to a polyolefin recording medium and scratch resistance. Preferably it is 98 mass% or more, More preferably, it is 100 mass%.

The mass ratio of polyester to polyolefin (polyester / polyolefin) in the polyester resin particles is from 65/35 to 99/1. When the mass ratio of polyester and polyolefin is within the above range, as will be described later, a dispersion of polyester resin particles (A) can be obtained by dispersing in an aqueous medium, and adhesion and resistance to polyolefin recording media can be obtained. A water-based ink excellent in scratching properties can be obtained.
The mass ratio of polyester to polyolefin (polyester / polyolefin) in the polyester resin particles is preferably 70/30 or more, more preferably 75/25 or more, from the viewpoint of obtaining excellent adhesion and scratch resistance to a polyolefin recording medium. More preferably, it is 80/20 or more, more preferably 85/15 or more, and from the same viewpoint, it is preferably 98/2 or less, more preferably 97/3 or less, and further preferably 95/5 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 excellent adhesion to a polyolefin recording medium and scratch resistance. More preferably, it is 80 nm or more, and preferably 1000 nm or less, more preferably 500 nm or less, still more preferably 400 nm or less, and further 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.

[Polyolefin]
The polyolefin in the polyester resin particles may be an olefin homopolymer or a copolymer of two or more olefins, such as polypropylene, propylene-α-olefin copolymer, ethylene-vinyl acetate copolymer, and the like. Is mentioned. As the copolymer, either a block copolymer or a random copolymer can be used.
The carbon number of the α-olefin in the propylene-α-olefin copolymer is preferably 4 or more, and preferably 15 or less, from the viewpoint of obtaining excellent adhesion to a polyolefin recording medium and scratch resistance. More preferably, it is 10 or less, More preferably, it is 8 or less.
Examples of the α-olefin include ethylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 4-methyl-1-pentene and the like.
Among these, polyolefin is preferably polypropylene or a propylene-α-olefin copolymer from the viewpoint of obtaining excellent adhesion to a recording medium made of polyolefin and scratch resistance.
In the case of a propylene-α-olefin copolymer, the amount of the polypropylene component is preferably 60 mol% or more, more preferably 65 mol in the polyolefin, from the viewpoint of obtaining excellent adhesion to a polyolefin recording medium and scratch resistance. % Or more, more preferably 70 mol% or more, and preferably 90 mol% or less, more preferably 80 mol% or less.

  The weight average molecular weight of the polyolefin is preferably 10,000 or more, more preferably 15,000 or more, still more preferably 50,000 or more, from the viewpoint of obtaining excellent adhesion to a polyolefin recording medium and scratch resistance. And it is preferably 200,000 or less, more preferably 150,000 or less. The weight average molecular weight is a value measured by gel permeation chromatography (standard material: polystyrene).

  The polyolefin used in the present invention is preferably a modified polyolefin from the viewpoint of inclusion in the polyester resin particles, and more preferably a polyolefin modified with a polar imparting agent containing chlorine (hereinafter simply referred to as “chlorinated polyolefin”). A polyolefin modified with an unsaturated carboxylic acid compound (hereinafter also simply referred to as “acid-modified polyolefin”) or a hydroxyl-modified polyolefin (hereinafter also simply referred to as “hydroxy-modified polyolefin”), A chlorinated polyolefin is preferred.

Chlorinated polyolefin is obtained by chlorination reaction of polyolefin.
The chlorination reaction can be carried out by a usual reaction method. For example, the above-mentioned polyolefin is dispersed or dissolved in a medium such as water or carbon tetrachloride, chloroform, and chlorine gas in the temperature range of 50 ° C. to 120 ° C. under pressure or normal pressure in the presence of a catalyst or under irradiation with ultraviolet rays. Is done by blowing.

  The chlorinated solvent used in the production of the obtained chlorinated polyolefin is usually distilled off by reduced pressure or the like or replaced with an organic solvent.

  The chlorine content of the chlorinated polyolefin is preferably 10% by mass or more, more preferably 20% by mass or more, still more preferably 25% by mass or more, and preferably 50% by mass from the viewpoint of inclusion in the polyester resin particles. Hereinafter, it is more preferably 40% by mass or less, and further preferably 35% by mass or less. The chlorine content in the present invention is a value measured according to JIS-K7229.

The acid-modified polyolefin is a polyolefin modified with an unsaturated carboxylic acid compound.
Examples of the unsaturated carboxylic acid-based compound include at least one selected from unsaturated carboxylic acids, unsaturated carboxylic acid derivatives, and unsaturated carboxylic acid anhydrides. An unsaturated carboxylic acid means an unsaturated compound containing a carboxy group. An unsaturated carboxylic acid derivative means a mono- or diester, amide, imide or the like of the compound. An unsaturated carboxylic acid anhydride means an anhydride of the compound.
As unsaturated carboxylic acid compounds, fumaric acid, maleic acid, itaconic acid, citraconic acid, aconitic acid, nadic acid and their anhydrides, methyl fumarate, ethyl fumarate, propyl fumarate, butyl fumarate, fumaric acid Dimethyl, diethyl fumarate, dipropyl fumarate, dibutyl fumarate, methyl maleate, ethyl maleate, propyl maleate, butyl maleate, dimethyl maleate, diethyl maleate, dipropyl maleate, dibutyl maleate, maleimide, N- Phenylmaleimide, (meth) acrylic acid, methyl (meth) acrylate, ethyl (meth) acrylate, cyclohexyl (meth) acrylate, lauryl (meth) acrylate, benzyl (meth) acrylate, N, N-dimethylaminoethyl (meth) Acrylate, and the like.
Examples of the acid modification method include a method in which an unsaturated carboxylic acid compound and a specific (meth) acrylic acid ester are used as a monomer in combination with the polyolefin as a monomer, followed by graft copolymerization for modification.
The graft amount of the unsaturated carboxylic acid compound is preferably 1% by mass or more, more preferably 5% by mass or more, still more preferably 8% by mass or more, and preferably 20%, based on the polyolefin before acid modification. It is at most 15% by mass, preferably at most 15% by mass.

The denaturing conditions can be performed according to a method such as a melting method or a solution method.
In the case of the melting method, the polyolefin is heated and melted (heated and melted) in the presence of a radical reaction initiator to react.
In the case of the solution method, the polyolefin is dissolved in an organic solvent and then reacted by heating and stirring in the presence of a radical reaction initiator. Examples of the organic solvent include aromatic solvents such as toluene and xylene. The temperature during the reaction is preferably 100 ° C. or higher and 180 ° C. or lower. Examples of the radical reaction initiator used in the melting method and the solution method include organic peroxide compounds and azonitriles.

  The acid-modified polyolefin may be further chlorinated. The chlorination reaction method and the chlorine content are the same as in the preferred examples described above.

Hydroxy-modified polyolefin is obtained by hydroxy-modifying polyolefin. Examples of the hydroxy modification method include a method of introducing a hydroxy group at the end of the polyolefin by polymerizing an olefin using a radical initiator or terminator having a hydroxyl group.
In addition, as a modified polyolefin by introducing a hydroxyl group or an amino group, as described in Japanese Patent No. 2768475, the polyolefin is brought into contact with an ethylenically unsaturated compound having a hydroxyl group or an amino group in the presence of a radical initiator. The method of obtaining is mentioned.

  Examples of commercially available polyolefins used in the present invention include, for example, 814B, 360T, 370M, 2027MB, E-415, E-480T, E-604, manufactured by Nippon Paper Industries Co., Ltd., Supercron (registered trademark) series; Made by company, Hardren (registered trademark) series, 14-LWP, 15-LLP, MD-15B, NA-3002; Nippon Paper Industries Co., Ltd., Auroren (registered trademark) series, 150S, 250S, 350S, 351S, 353S, 359S, AE-202, AE-301; Unitika Ltd., Arrow Base (registered trademark) series, SB-1200, SB-1010, SE-1200; Sumika Chemtex Co., Ltd. Sumifit (registered trademark) CK1D: 100 manufactured by Sanyo Kasei Kogyo Co., Ltd., Yumex series S, 110TS, 1001,1010; manufactured by Mitsubishi Chemical Corporation, polytail (registered trademark).

〔polyester〕
The polyester 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.

The raw material monomer of the polyester is not particularly limited, and an arbitrary alcohol component and an organic acid component having any acid group, preferably a carboxylic acid component, are used.
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 consists of dicarboxylic 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 preferred from the viewpoint of improving adhesion to a polyolefin recording medium and scratch 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 polyolefin recording medium and scratch resistance, it is preferably at least one selected from fumaric acid, adipic acid, sebacic acid, and dodecenyl succinic acid, more preferably fumaric acid. Or it is adipic acid.
Examples of the alicyclic dicarboxylic acid include cyclohexane dicarboxylic acid. Examples of the trivalent or higher polyvalent carboxylic acid include trimellitic acid, 2,5,7-naphthalene tricarboxylic acid, and pyromellitic acid.

  The carboxylic acid component is preferably at least one selected from isophthalic acid, terephthalic acid, fumaric acid, adipic acid, sebacic acid, and dodecenyl succinic acid, from the viewpoint of improving adhesion to polyolefin recording media and scratch resistance. More preferably, it is at least one selected from terephthalic acid, fumaric acid and adipic acid.

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

Examples of the alcohol component include diols, trihydric or higher polyhydric alcohols, and the like is preferable.
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 polyolefin recording medium and scratch 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. Further, from the same viewpoint, the average value of the sum of x and y is preferably 7 or less, more preferably 5 or less, and still more preferably 3 or less.
The x OR ¹ and the y R ² O may be the same or different, but are preferably the same from the viewpoint of improving the fixing property of the ink to the 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 and hydrogenated bisphenol A.

As the alcohol component, from the viewpoint of improving adhesion to a recording medium made of polyolefin and scratch resistance, an adduct of bisphenol A having 2 or 3 carbon oxides (average added mole number of 1 to 16), and It is at least one selected from hydrogenated bisphenol A, and from the viewpoint of improving adhesion and scratch resistance to polyolefin recording media, preferably propylene oxide adduct of bisphenol A or ethylene oxide adduct of bisphenol A, more preferably It is a propylene oxide adduct of bisphenol A.
The content of the alkylene oxide adduct of bisphenol A in the alcohol component, which is a raw material monomer for polyester, is preferably 50 mol% or more, more preferably from the viewpoint of improving adhesion to a polyolefin recording medium and scratch resistance. Is 80 mol% or more, more preferably 90 mol% or more, and preferably 100 mol% or less.

  The said alcohol 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 is a viewpoint of improving the adhesion to the polyolefin recording medium and the scratch resistance. Therefore, 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 is preferably 25 ° C. or higher, more preferably 35 ° C. or higher, still more preferably 50 ° C. or higher, and preferably from the viewpoint of improving adhesion to a polyolefin recording medium and scratch resistance. It is 95 ° C. or lower, more preferably 80 ° C. or lower, more preferably 75 ° C. or lower, and further preferably 70 ° C. or lower.

The softening point of the polyester is preferably 70 ° C. or higher, more preferably 80 ° C. or higher, more preferably 90 ° C. or higher, from the viewpoint of improving the adhesion to the polyolefin recording medium and the scratch resistance, and the same viewpoint. Therefore, it 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 mixed, the glass transition temperature and softening point are the values obtained by the method of an Example as a mixture of 2 or more types of polyester, respectively.

The acid value of the polyester is preferably 5 mgKOH / g or more, more preferably 10 mgKOH / g or more, still more preferably 15 mgKOH / g or more, from the viewpoint of improving the dispersion stability of the resin particles in the aqueous medium. Preferably it is 35 mgKOH / g or less, More preferably, it is 30 mgKOH / g or less, More preferably, it is 25 mgKOH / g or less.
The desired softening point, glass transition temperature, and acid value of the polyester can be 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. .
Polyesters may be used alone or in combination of two or more.

The polyester can be produced by subjecting a carboxylic acid component and an alcohol component to a polycondensation reaction. For example, it is produced by polycondensing the alcohol component and the carboxylic acid component at a temperature of 120 ° C. or higher and 250 ° C. or lower using an esterification catalyst and a polymerization inhibitor as necessary in an inert gas atmosphere. be able to.
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 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 carboxylic acid component and the alcohol component, and The amount is preferably 1.5 parts by mass or less, more preferably 1.0 part 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 part by mass or more, more preferably 0.005 part by mass or more, and preferably 0 with respect to 100 parts by mass of the total amount of the carboxylic acid component and the alcohol component. 0.5 parts by mass or less, more preferably 0.1 parts by mass or less.

  In the present invention, the polyester includes not only an unmodified polyester as long as it has an acid group, but also a polyester modified to such an extent that the properties are not substantially impaired. Examples of the modified polyester include grafting and blocking with phenol, urethane, epoxy and the like by the methods described in JP-A-11-133668, JP-A-10-239903, JP-A-8-20636, and the like. And a composite resin having two or more kinds of 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.

[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 of preferably less than 6% by mass in 100 g of water (20 ° C.). 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 adhesion to the polyolefin recording medium and the scratch resistance. Yes, and preferably 25% by mass or less, more preferably 10% by mass or less, and 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 20 in the ink, from the viewpoint of improving adhesion to the polyolefin recording medium and scratch 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 and a polymer.
Below, the polymer particle containing a coloring agent is demonstrated.

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, from the viewpoint of improving the storage stability and dischargeability of the ink, (a) an ionic monomer (hereinafter, also simply referred to as “component (a)”) and (b) a hydrophobic monomer (hereinafter, referred to as “vinyl monomer”). A vinyl polymer obtained by copolymerizing a monomer mixture (hereinafter also simply referred to as “monomer mixture”) including “(b) component”) is preferable. This vinyl polymer has a structural unit derived from the component (a) and a structural unit derived from the component (b).

(A) Examples of the ionic monomer include an anionic monomer and a cationic monomer, and among these, an anionic monomer is preferable from the viewpoint of improving the dispersion stability of the polymer particles containing the colorant in the ink. It is. 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, from the viewpoint of improving the dispersion stability of the polymer particles containing the colorant in the ink, it is preferably at least one selected from carboxylic acid monomers, more preferably acrylic acid and methacrylic acid. .

(B) Hydrophobic monomers include alkyl (meth) acrylates, styrene monomers, aromatic group-containing (meth) acrylates, and the like.
The alkyl (meth) acrylate is preferably an alkyl (meth) acrylate having an alkyl group having 1 to 22 carbon atoms, more preferably 6 to 18 carbon atoms. “(Meth) acrylate” represents at least one selected from acrylate and methacrylate.

Examples of the styrenic monomer include styrene, 2-methylstyrene, divinylbenzene, and the like. From the viewpoint of improving the dispersion stability of the polymer particles containing the colorant in the ink, styrene is preferable.
Examples of the aromatic group-containing (meth) acrylate include benzyl (meth) acrylate and phenoxyethyl (meth) acrylate, and benzyl (meth) acrylate is preferable.
(B) Two or more types of the above-mentioned monomers can be used as the hydrophobic monomer. Styrenic monomers and aromatic group-containing (meth) acrylates can be used in combination, and benzyl (meth) acrylate and styrene can be used in combination. From the viewpoint of improvement, it is more preferable to use benzyl (meth) acrylate alone.

From the viewpoint of improving the dispersion stability of the polymer particles containing the colorant in the ink, the vinyl polymer further contains a structural unit derived from (c) a macromer (hereinafter, also simply referred to as “(c) component”). Those that do are preferred.
(C) The macromer is a compound having a polymerizable functional group at one end, preferably having a number average molecular weight of 500 or more and 100,000 or less. Examples of the polymerizable functional group present at one end include a (meth) acryloyloxy group. From the viewpoint of improving the dispersion stability of the polymer particles containing the colorant in the ink, a methacryloyloxy group is preferable. is there. (C) The number average molecular weight of the macromer is more preferably 1,000 or more and 10,000 or less from the viewpoint of improving the dispersion stability of the polymer particles containing the colorant in the ink. The number average molecular weight is measured by gel permeation chromatography, and is measured using chloroform or the like as a solvent and polystyrene or the like as a standard substance.

(C) The macromer is preferably at least one selected from an aromatic group-containing monomer-based macromer and a silicone-based macromer from the viewpoint of improving the dispersion stability of the polymer particles containing the colorant in the ink. Aromatic group-containing monomeric macromers are preferred.
Examples of the aromatic group-containing monomer constituting the aromatic group-containing monomer-based macromer include the aromatic group-containing monomers described in the above (b) hydrophobic monomer, preferably at least selected from styrene and benzyl (meth) acrylate. One type, more preferably styrene.
Examples of the silicone macromer include organopolysiloxane having a polymerizable functional group at one end.

From the viewpoint of improving the dispersion stability of the polymer particles containing the colorant in the ink, the vinyl-based polymer is further derived from (d) a nonionic monomer (hereinafter also simply referred to as “component (d)”). What contains a structural unit is preferable.
As the component (d), polyalkylene glycol (meth) acrylate, alkoxy polyalkylene glycol (meth) acrylate, phenoxy (ethylene glycol / propylene glycol copolymer) (n = 1 to 30, ethylene glycol therein: n = 1) -29) (meth) acrylate etc. are mentioned. Among these, from the viewpoint of improving dispersion stability of the polymer particles containing the colorant in the ink, preferably alkoxy polyalkylene glycol (meth) acrylate, more preferably methoxypolyethylene glycol (n = 1 to 30) ( (Meth) acrylate.

  The components (a) to (d) can be used singly or in combination of two or more.

Components (a) to (d) in the monomer mixture of the above-mentioned components (a) to (d) at the time of vinyl polymer production (contents as unneutralized amounts; the same applies hereinafter) or water-insoluble polymers The content of the structural unit derived from is as follows.
The content of the component (a) is preferably 2% by mass or more, more preferably 5% by mass or more, and still more preferably 8% by mass from the viewpoint of improving dispersion stability of the polymer particles containing the colorant in the ink. %, And preferably 40% by mass or less, more preferably 30% by mass or less, and still more preferably 25% by mass or less.
The content of the component (b) is preferably 5% by mass or more, more preferably 10% by mass or more, and preferably from the viewpoint of improving dispersion stability of the polymer particles containing the colorant in the ink. Is 98 mass% or less, More preferably, it is 80 mass% or less.
When the component (c) is contained, the content of the component (c) is preferably 1% by mass or more, more preferably 5 from the viewpoint of improving dispersion stability of the polymer particles containing the colorant in the ink. It is at least mass%, and is preferably at most 25 mass%, more preferably at most 20 mass%.
In the case of containing the component (d), the content of the component (d) is preferably 5% by mass or more, more preferably 10 from the viewpoint of improving dispersion stability of the polymer particles containing the colorant in the ink. It is at least 50% by mass, and preferably at most 50% by mass, more preferably at most 40% by mass.
In addition, the mass ratio of [(a) component / [(b) component + (c) component]] in the case of containing the component (c) determines the dispersion stability of the polymer particles containing the colorant in the ink. From the viewpoint of improving, it is preferably 0.01 or more, more preferably 0.02 or more, still more preferably 0.03 or more, and preferably 1.00 or less, more preferably 0.67 or less, still more preferably. 0.50 or less.

  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 obtain an aqueous dispersion of polymer particles containing a colorant.

  As a method for obtaining a dispersion of polymer particles containing a colorant, first, a water-insoluble polymer solution is obtained by dissolving a water-insoluble polymer in an organic solvent. Next, a dispersion of polymer particles containing an oil-in-water colorant, in which a colorant, water, and, if necessary, a neutralizing agent, a surfactant and the like are added to the obtained water-insoluble polymer solution and mixed. Is preferred. Although there is no restriction | limiting in the order added to the organic solvent solution of a water-insoluble polymer, It is preferable to add in order of water, a neutralizing agent, and a coloring agent.

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 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. It is preferable to control the volume average particle diameter (D _V ) 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 organic solvent in the aqueous dispersion containing the polymer particles containing the obtained colorant is preferably substantially removed, but may remain as long as the object of the present invention is not impaired. The amount of the residual organic solvent is preferably 0.1% by mass or less, more preferably 0.01% by mass or less. If necessary, the dispersion can be heated and stirred before the organic solvent is distilled off.

  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 obtaining excellent adhesion and scratch resistance to polyolefin recording media. , 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, dihydroxyethyl lauryl amine oxide, and the like. Is mentioned.
Examples of the silicone surfactant include polyester-modified silicone and polyether-modified silicone.
Examples of the fluorine-based surfactant include a perfluoroalkyl sulfonic acid compound, a perfluoroalkyl carboxylic compound, a perfluoroalkyl phosphate compound, and a perfluoroalkyl ethylene oxide adduct.
One surfactant may be used alone, or two or more surfactants may be used in combination.
Among these, at least one selected from a nonionic surfactant and a silicone-based surfactant is preferable, at least one selected from glycol ether, polyester-modified silicone, and polyether-modified silicone is more preferable, and glycol ether is 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.

There is no restriction | limiting in particular as an antifoamer, According to the objective, it can select suitably, For example, a silicone type antifoamer, a polyether type antifoamer, a fatty-acid-ester type antifoamer, etc. are mentioned.
Examples of the antiseptic and antifungal agent include 1,2-benzisothiazolin-3-one, sodium dehydroacetate, sodium sorbate, sodium 2-pyridinethiol-1-oxide, sodium benzoate, sodium pentachlorophenol, etc. Is mentioned.
Examples of the rust inhibitor include acidic 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 phenolic antioxidants (including hindered phenolic antioxidants), amine antioxidants, sulfurous 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 polyester / polyolefin, organic solvent, and basic compound having a mass ratio (polyester / polyolefin) of 65/35 to 99/1 Step (2): obtained in step (1) A step of mixing and emulsifying the mixture with an aqueous medium to obtain an aqueous dispersion of polyester resin particles Step (3): An aqueous dispersion of polyester resin particles obtained in Step (2) and an aqueous dispersion containing a colorant Mixing water and obtaining water-based ink

[Step (1)]
In step (1), a resin containing polyester and polyolefin is dissolved in an organic solvent to obtain a mixture containing polyester and polyolefin. The mass ratio of polyester to polyolefin (polyester / polyolefin) is preferably in the same range as the mass ratio of polyester to polyolefin in the polyester resin particles.
When obtaining a solution containing polyester and polyolefin, a mixture of polyester and polyolefin may be used in advance, but these resins are simultaneously added to an organic solvent and dissolved to contain polyester and polyolefin. A solution may be obtained.
From the viewpoint of improving the affinity of the resin containing polyester and polyolefin to the aqueous medium, improving the dispersion stability of the resin particle dispersion, and improving the adhesion and scratch resistance to the polyolefin recording medium. 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 salt substances. Among these, sodium hydroxide or ammonia is preferable from the viewpoint of improving the dispersion stability of the polyester resin particles.
The degree of neutralization (mol%) of the polyester with the basic compound is preferably 10 mol% or more, more preferably 50 mol% or more, and still more preferably 60 mol%, from the viewpoint of improving the dispersion stability of the polyester resin particles. And more preferably 150 mol% or less, more preferably 100 mol% or less, still more preferably 80 mol% or less.
In addition, the neutralization degree (mol%) of polyester can be calculated | required by following Formula.
Degree of neutralization = {[addition mass of neutralizer (g) / equivalent of neutralizer] / [[acid value of polyester (mgKOH / g) × mass of polyester (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 , Preferably 80% by mass or more, more preferably 90% by mass or more, still more preferably 95% by mass or more, still more preferably substantially 100% by mass, still more 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 50 C or lower.
From the viewpoint of improving the dispersion stability of the polyester resin particles and obtaining excellent adhesion and scratch resistance to the polyolefin recording medium, 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 from the viewpoint of obtaining excellent adhesion to a polyolefin recording medium and scratch 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, from the viewpoint of improving excellent adhesion to a polyolefin recording medium and scratch resistance. Preferably it is 70 nm or more, More preferably, it is 80 nm or more, Preferably it is 1000 nm or less, More preferably, it is 500 nm or less, More preferably, it is 400 nm or less, More preferably, it is 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 the above-mentioned aqueous dispersion.
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 maintaining the viscosity of the ink properly and obtaining excellent adhesion and scratch resistance to the polyolefin recording medium. 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 contained in the water-based ink is preferably 1.0% by mass or more in the ink from the viewpoint of maintaining the viscosity of the ink properly and obtaining excellent adhesion and scratch resistance to the polyolefin recording medium. More preferably, it is 2.0 mass% or more, More preferably, it is 3.0 mass% or more, Preferably it is 19.8 mass% or less, More preferably, it is 15 mass% or less, More preferably, it is 10 mass% or less. is there.
The content of the polyolefin contained in the water-based ink is preferably 0.2% by mass or more, more preferably 0.3% by mass or more, in the ink, from the viewpoint of obtaining excellent adhesion to a polyolefin recording medium and scratch resistance. More preferably, the content is 0.4% by mass or more, and preferably 5% by mass or less, more preferably 3% by mass or less, and still more preferably 2% 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 inkjet recording method, a polyolefin recording medium to which the aqueous ink is adhered after the aqueous ink of the present invention is adhered to a polyolefin recording medium by an inkjet recording method is used. Heat to 40 ° C or higher and 100 ° C or lower. Of these, the water-based ink of the present invention can be suitably applied to a polyolefin recording medium to form an image.

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. Suitable for use in polyolefin and recording media suitable for commercial and industrial label packaging printing, suitable for commercial or industrial printing, suitable for commercial or industrial label packaging printing ing.
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.
Examples of films that can be generally obtained include KAINUS KEE70CA (manufactured by Lintec Corporation, polyethylene), YUPO SG90 PAT1 (manufactured by Lintec Corporation, polypropylene), FOR, FOA (both manufactured by Phutamura Chemical Co., Ltd., polypropylene) and the like. Can be mentioned.

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 polyolefin recording medium, the polyolefin recording medium to which the water-based ink is attached is heated to 40 ° C. or higher and 100 ° C. or lower. The resin constituting the polyester resin particles in the water-based ink diffuses on the printing surface of the polyolefin recording medium and can act as a colorant fixing aid when forming a coating film. Adhesion and scratch resistance can be further improved.
The heating temperature of the polyolefin recording medium is preferably 50 ° C. or higher, more preferably 60 ° C. or higher, and preferably 90 ° C. or lower, from the viewpoint of obtaining excellent adhesion and scratch resistance to the polyolefin recording medium. 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, and a load of 1.96 MPa was applied by a plunger, and the diameter was 1 mm and the length was 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.), 0.01 to 0.02 g of a sample is weighed in an aluminum pan, heated to 200 ° C., and the temperature is lowered from that temperature. The sample for measurement was prepared by cooling to 0 ° C. at a rate of 10 ° C./min. 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 Size of Polyester Resin Particles (D _v )]
(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 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, and the temperature is 25 ° C. and the number of integrations is 100. Water is used as the refractive index of the dispersion solvent. Refractive index (1.333) was entered.

[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, add approximately 1.0 g of the sample to it, mix and then weigh accurately. 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.

[Volume Average Particle Size (D _V ) of Polymer Particles Containing Colorant (Pigment-Containing Anionic Polymer Particles)]
Using a laser particle analysis system “ELS-Z2” (manufactured by Otsuka Electronics Co., Ltd.), a cumulant analysis was performed and measured. A dispersion diluted with water so that the concentration of particles to be measured was about 5 × 10 ⁻³ mass% was used. The measurement conditions were a temperature of 25 ° C., an angle between incident light and a detector of 90 °, and the number of integrations of 100. The refractive index of water (1.333) was input as the refractive index of the dispersion solvent.

[Evaluation of adhesion]
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 corona-treated PP film “FOR-15” (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 10 stages. The higher the score, the better the adhesion to PP.
<Evaluation criteria>
No peeling: 10 points Peeling but peeling area less than 5%: 9 points peeling area 5% or more and less than 10%: 8 points peeling area 10% or more but less than 20%: 7 points peeling area 20% or more but less than 30%: 6 points Peeling area 30% or more and less than 40%: 5 points Peeling area 40% or more and less than 50%: 4 points Peeling area 50% or more and less than 60%: 3 points Peeling area 60% or more and less than 70%: 2 points Peeling area 70% or more: 1 point

[Evaluation of scratch 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 corona-treated PP film “FOR-15” (Futamura Chemical Co., Ltd.). Using a Gakushin friction tester "RT-300" (manufactured by Daiei Kagaku Seiki Seisakusho Co., Ltd.), the coated surface of the sample is loaded with 500 g of plain paper (trade name: "XEROX 4200DP", Fuji Xerox Co., Ltd.) After rubbing at 100 times, the state of the coated surface was visually evaluated in the following five stages. The higher the score, the better the scratch resistance.
<Evaluation criteria>
No scratches or peeling: 5 points Scratches on a part of the coated surface: 4 points Scratches on the whole coated surface: 3 points Scratches on the whole coated surface and partly peeled: 2 points There is peeling on the whole coated surface: 1 point

Production Example 1 (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 6160 g of polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane, 2125 g of fumaric acid, 4 g of 4-tert-butylcatechol and 10 g of dibutyltin oxide were added, and the temperature was raised to 210 ° C. over 5 hours with stirring in a nitrogen atmosphere. After holding at 210 ° C. for 2 hours, 8.3 kPa The reaction was carried out until the softening point reached 100 ° C. to obtain polyester A. The properties of polyester A are shown in Table 1.

Production Example 2 (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 replaced with nitrogen, and 5950 g of polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane, 1975 g of terephthalic acid and 10 g of dibutyltin oxide were added, the temperature was raised to 230 ° C. with stirring in a nitrogen atmosphere, and the temperature was maintained for 5 hours. Then, the pressure in the flask was further reduced and maintained at 8.3 kPa for 1 hour. Then, after cooling to 210 ° C. and returning to atmospheric pressure, 493 g of fumaric acid and 0.5 g of 4-tert-butylcatechol were added and held at a temperature of 210 ° C. for 5 hours, and then the pressure in the flask was further lowered. , And held at 8.3 kPa for 4 hours to obtain polyester B. The properties of polyester B are shown in Table 1.

Production Example 3 (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 replaced with nitrogen, and 1176 g of polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane, 4368 g of polyoxyethylene (2.2) -2,2-bis (4-hydroxyphenyl) propane, 1394 g of terephthalic acid, and 10 g of dibutyltin oxide were added, and the temperature was raised to 230 ° C. with stirring in a nitrogen atmosphere. After holding for a period of time, the pressure in the flask was further lowered and held at 8.3 kPa for 1 hour. Then, after cooling to 210 ° C. and returning to atmospheric pressure, 292 g of fumaric acid, 981 g of adipic acid and 0.5 g of 4-tert-butylcatechol were added and kept at a temperature of 210 ° C. for 4 hours. Was reduced and held at 8.3 kPa for 3 hours to obtain polyester C. The properties of Polyester C are shown in Table 1.

Production Example 4 (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 2730 g of polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane, 1268 g of polyoxyethylene (2.2) -2,2-bis (4-hydroxyphenyl) propane, 920 g of hydrogenated bisphenol A (2,2-bis (4-hydroxycyclohexyl) propane), 2149 g of terephthalic acid, and dibutyltin oxide 10 g was added, the temperature was raised to 230 ° C. while stirring in a nitrogen atmosphere, and the temperature was maintained for 4 hours. Then, the pressure in the flask was further reduced and maintained at 8.3 kPa for 1 hour. Then, after cooling to 210 ° C. and returning to atmospheric pressure, 271 g of fumaric acid and 0.5 g of 4-tert-butylcatechol were added and kept at a temperature of 210 ° C. for 4 hours, and then the pressure in the flask was further lowered. , And held at 8.3 kPa for 3 hours to obtain polyester D. The properties of polyester D are shown in Table 1.

Production Example 5 (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 was added with 180 g of polyester A and polyolefin A (acid-modified chlorinated polypropylene “ Superglon 360T "(manufactured by Nippon Paper Industries Co., Ltd., ethyl acetate solution product, solid content 60% by mass, chlorine content 31% by mass)) was added and mixed with 200 g of methyl ethyl ketone (MEK) at 30 ° C. to dissolve the resin. . Subsequently, 35.2 g of 5 mass% sodium hydroxide aqueous solution was added, and it stirred for 30 minutes, and obtained the organic-solvent type slurry. While stirring at 30 ° C., 497 g of deionized water was added dropwise 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. The characteristics of the polyester resin particles A in the obtained aqueous dispersion are shown in Table 2-1.

Production Examples 6 to 14 (Production of aqueous dispersion of polyester resin particles B to J)
In Production Example 5, the types and amounts of polyester, the types and amounts of polyolefin, the types and amounts of organic solvents, the addition amount of 5 mass% sodium hydroxide aqueous solution, and the addition amount of deionized water are shown in Tables 2-1 and 2 An aqueous dispersion of polyester resin particles B to J was obtained in the same manner as in Production Example 5 except that the content was changed to that shown in -2. The characteristics of the polyester resin particles in the obtained aqueous dispersion are shown in Tables 2-1 and 2-2.

Production Example 15 (Production of aqueous dispersion of polyester resin particles K)
In the same manner as in Production Example 5, except that the amount of polyester A was changed to 120 g, the amount of polyolefin was changed to 133 g, and the addition amount of 5 mass% sodium hydroxide aqueous solution was changed to 23.5 g, respectively. An attempt was made to produce an aqueous dispersion of resin particles K, but aggregates were formed during the addition of deionized water, and the resin particles could not be dispersed.

Production Example 16 (Preparation of aqueous dispersion of water-insoluble polymer particles containing 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% by mass ammonia water and 236.5 g of ion-exchanged 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, 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 Avisia) and 19.8 g of ion-exchanged 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 9, Comparative Example 4 (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 ion-exchanged water (26.6 parts by mass) are mixed, and a magnetic stirrer is mixed. 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 16 (4.0 parts by mass in terms of pigment content (in 100 parts by mass of aqueous ink)) is 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 3-1 and Table 3-2 (5.0 parts by weight in terms of solid content (100 parts by weight of aqueous ink) The mixture was stirred and mixed while dropping the middle)) with a dropper. 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. The evaluation results of the obtained water-based ink are shown in Tables 3-1 and 3-2.

Comparative Example 1 (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 ion-exchanged water (26.6 parts by mass) are mixed, and a magnetic stirrer is mixed. 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 16 (4.0 parts by mass in terms of pigment content (in 100 parts by mass of aqueous ink)) is stirred with a magnetic stirrer. While mixing the whole mixed solution, 15.0 parts by mass of an aqueous dispersion of polyester resin particles shown in Table 3-2 (4.5 parts by mass in terms of solid content (in 100 parts by mass of aqueous ink)) and polyolefin 1.7 parts by mass of dispersion A (aqueous product of polyolefin resin particles, 0.5 parts by mass in terms of solid content (in 100 parts by mass of water-based ink)) was added with stirring while being dropped. 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. The evaluation results of the obtained water-based ink are shown in Table 3-2.

Comparative Example 2 (Production of water-based ink)
A water-based ink was obtained in the same manner as in Comparative Example 1 except that the polyolefin dispersion A was changed to the polyolefin dispersion B in Comparative Example 1. The evaluation results of the obtained water-based ink are shown in Table 3-2.

Comparative Example 3 (Production of water-based ink)
In Comparative Example 1, the amount of the polyolefin dispersion A used was changed to 16.7 parts by mass (0.5 parts by mass in terms of solid content (in 100 parts by mass of water-based ink)), and the polyester resin particles were not used. A water-based ink was obtained in the same manner as in Comparative Example 1. The evaluation results of the obtained water-based ink are shown in Table 3-2.

  From the results of Tables 3-1 and 3-2, the water-based inks of Examples 1 to 9 using polyester resin particles containing polyolefin are Comparative Examples 1 and 2, which are water-based inks in which polyolefin and polyester are added separately. It can be seen that the water-based ink of Comparative Example 3 which is a water-based ink not containing polyester and the water-based ink of Comparative Example 4 which is a water-based ink not containing polyolefin are superior in adhesion to polypropylene media and scratch resistance of printed matter.

  According to the present invention, it is possible to provide a water-based ink having excellent adhesion and scratch resistance to a polyolefin recording medium and a method for producing the same, and therefore can be applied to fields such as commercial label printing.

Claims (7)

A water-based ink containing a colorant and polyester resin particles,
A water-based ink in which the polyester resin particles contain polyester and polyolefin, and the mass ratio of polyester to polyolefin (polyester / polyolefin) in the polyester resin particles is from 65/35 to 99/1.   The water-based ink according to claim 1, wherein the polyolefin is a modified polyolefin. The water-based ink according to claim 1 or 2, wherein the volume average particle diameter (D _V ) of the polyester resin particles is 20 nm or more and 1000 nm or less.   The water-based ink according to any one of claims 1 to 3, wherein the glass transition temperature of the polyester in the polyester resin particles is 25 ° C or higher and 95 ° C or lower.   The water-based ink according to any one of claims 1 to 4, wherein the content of the polyolefin in the water-based ink is 0.2% by mass or more and 5% by mass or less. A method for producing a water-based ink, comprising the following steps (1) to (3).
Step (1): Step of obtaining a mixture of polyester / polyolefin, organic solvent, and basic compound having a mass ratio (polyester / polyolefin) of 65/35 to 99/1 Step (2): obtained in step (1) A step of mixing and emulsifying the mixture with an aqueous medium to obtain an aqueous dispersion of polyester resin particles Step (3): An aqueous dispersion of polyester resin particles obtained in Step (2) and an aqueous dispersion containing a colorant Mixing water and obtaining water-based ink   An inkjet in which the water-based ink according to any one of claims 1 to 5 is attached to a polyolefin recording medium by an ink jet recording method, and then the polyolefin recording medium to which the water-based ink is attached is heated to 40 ° C or higher and 100 ° C or lower. Recording method.