Polyester resin water dispersion

Abstract

To provide a polyester resin water dispersion capable of obtaining a printed matter which is excellent in storage stability and adhesiveness to a resin recording medium having polarity such as PVC of a coating film formed, has excellent storage stability even when used in an aqueous ink and is excellent in adhesiveness when printed on the resin recording medium and scratch resistance to a solvent such as an alcohol and to provide an aqueous ink containing the polyester resin water dispersion.SOLUTION: There are provided [1] a polyester resin water dispersion containing polyester resin particles, wherein the polyester resin particles contains a polyester resin A containing a constitutional unit derived from an alcohol component and a constitutional unit derived from a carboxylic acid component, the alcohol component contains an alkylene oxide adduct of bisphenol A and 3-methyl-1,5-pentanediol and the content of 3-methyl-1,5-pentanediol in the alcohol component is 40 to 75 mol%; and [2] an aqueous ink containing the polyester resin water dispersion described in [1] and a coloring agent.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to an aqueous polyester resin dispersion and a water-based ink containing the aqueous polyester resin dispersion. [Background technology]

[0002] In the fields of commercial and industrial printing, such as product packaging printing and label printing for advertising, printing has traditionally been done using solvent-based inks or UV-curable inks on resinous printing media such as PVC (polyvinyl chloride), PET (polyethylene terephthalate), PE (polyethylene), PP (polypropylene), and NY (nylon). In response to this, from the viewpoints of reducing environmental load, saving energy, safety, and the like, attempts to incorporate a resin aqueous dispersion have been considered as a method for improving the performance of the ink coating film. For example, Patent Document 1 describes an aqueous polyester resin dispersion containing a polyester resin having an acid value of 8 mgKOH / g or more and a glass transition temperature of 40 to 120°C, for the purpose of providing an aqueous polyester resin dispersion which produces a coating film having excellent solvent resistance, etc., and which does not contain isophthalic acid as a constituent acid component, but contains 95 to 100 mol % of terephthalic acid and 1 to 5 mol % of trimellitic acid, and which contains 25 to 80 mol % of an alkylene oxide derivative of bisphenols as a constituent alcohol component. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2012-72308 A Summary of the Invention [Problem to be solved by the invention]

[0004] Here, resin printing media such as PVC, PET, PE, PP, and NY are non-water-absorbent, and water-based inks do not penetrate into the interior of the printing media. Therefore, when performing so-called surface printing using a resin printing medium, it tends to be difficult to obtain a printed matter that has high adhesion to the resin printing medium. In particular, adhesion to polar resin printing media such as PVC film is insufficient. In addition, for example, alcohol is used for disinfection and sterilization in food and medical facilities. When performing so-called surface printing using resin films for containers used in these locations, printed matter is required to have abrasion resistance against solvents such as alcohol. Furthermore, with the widespread use of resin water dispersions and inks using the same, there is a demand for further improvement in the storage stability of resin water dispersions and water-based inks using the same. An object of the present invention is to provide an aqueous polyester resin dispersion which has excellent storage stability and adhesion of the coating film formed to a resin printing medium having polarity such as PVC, and which also has excellent storage stability when used in an aqueous ink, and which, when printed on the resin printing medium, can give a printed matter which has excellent adhesion and abrasion resistance to solvents such as alcohol, and an aqueous ink containing the aqueous polyester resin dispersion. [Means for solving the problem]

[0005] The present inventors have found that the above-mentioned problems can be solved by making the polyester resin contained in the polyester resin particles of the polyester resin aqueous dispersion contain structural units derived from an alcohol component containing an alkylene oxide adduct of bisphenol A and 3-methyl-1,5-pentanediol, and by setting the content of 3-methyl-1,5-pentanediol in the alcohol component to a specific range.

[0006] That is, the present invention provides the following [1] and [2]. [1] A polyester resin aqueous dispersion containing polyester resin particles, The polyester resin particles contain a polyester resin A including a structural unit derived from an alcohol component and a structural unit derived from a carboxylic acid component, the alcohol component comprises an alkylene oxide adduct of bisphenol A and 3-methyl-1,5-pentanediol; The content of 3-methyl-1,5-pentanediol in the alcohol component is 40 mol % or more and 75 mol % or less in the polyester resin aqueous dispersion. [2] A water-based ink comprising the polyester resin aqueous dispersion according to [1] above and a colorant. Effect of the Invention

[0007] According to the present invention, it is possible to provide an aqueous polyester resin dispersion and an aqueous ink containing the aqueous polyester resin dispersion, which have excellent storage stability and adhesion to polar resin printing media such as PVC in the coating film that is formed, and which also have excellent storage stability when used in an aqueous ink, and which, when printed on the resin printing medium, can give a printed item that has excellent adhesion and abrasion resistance to solvents such as alcohol. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] [Polyester resin water dispersion] The polyester resin aqueous dispersion of the present invention is an aqueous polyester resin dispersion containing polyester resin particles, the polyester resin particles containing polyester resin A including structural units derived from an alcohol component and structural units derived from a carboxylic acid component, the alcohol component containing an alkylene oxide adduct of bisphenol A (2,2-bis(4-hydroxyphenyl)propane) and 3-methyl-1,5-pentanediol, and the content of 3-methyl-1,5-pentanediol in the alcohol component being 40 mol % or more and 75 mol % or less. The polyester resin aqueous dispersion of the present invention is preferably one in which polyester resin particles are dispersed in an aqueous medium. In the present invention, the term "aqueous system" means that water accounts for the largest proportion of the medium. As the water in the aqueous medium, deionized water, ion-exchanged water or distilled water is preferably used. The aqueous medium may further contain an organic solvent, such as aliphatic alcohols having 1 to 4 carbon atoms, such as methanol, ethanol, and 2-propanol, ketones having 3 to 8 carbon atoms, such as acetone and methyl ethyl ketone, and ethers, such as tetrahydrofuran, that dissolve in water. From the viewpoint of environmental friendliness, the water content in the aqueous medium is preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 90% by mass or more, and still more preferably 95% by mass or more.

[0009] According to the present invention, it is possible to provide a polyester resin aqueous dispersion that has excellent storage stability and adhesion of the coating film formed to a polar resin printing medium such as PVC (hereinafter also referred to as "adhesion"), and that has excellent storage stability even when used in a water-based ink, and that can obtain a printed matter that has excellent adhesion and abrasion resistance to solvents such as alcohol (hereinafter also referred to as "alcohol resistance") when printed on the resin printing medium, and a water-based ink containing the polyester resin aqueous dispersion. The reason for such effects is not clear, but it is thought to be as follows. Polyester resins containing structural units derived from alkylene oxide adducts of bisphenol A have hydrophobic and rigid bisphenol A moieties, which improve the storage stability of aqueous dispersions and the alcohol resistance of printed materials. However, on the other hand, the number of polar moieties such as ester bonds in the polyester resin is reduced, which reduces adhesion to polar resin printing media such as PVC. In the present invention, the alcohol component constituting the polyester resin contained in the polyester resin particles contains, in addition to the alkylene oxide adduct of bisphenol A, a specific amount of 3-methyl-1,5-pentanediol as an aliphatic primary diol having a side chain and a not particularly large molecular weight. This makes it possible to introduce flexible and locally high-density ester bonds into the polyester resin, which is thought to improve adhesion to polar resin printing media. In addition, since 3-methyl-1,5-pentanediol has a methyl group in the side chain, it is believed that it can suppress the affinity with aqueous media and the crystallization caused by the aliphatic alcohol structure, and further suppresses hydrolysis of the polyester resin, thereby improving storage stability. In the present invention, it is believed that by adjusting the concentration of ester bonds due to the content of 3-methyl-1,5-pentanediol in the alcohol component constituting the polyester resin contained in the polyester resin particles being within a specific range, and by adjusting the effect of steric hindrance due to the methyl group in the side chain of 3-methyl-1,5-pentanediol, it is possible to improve adhesion while maintaining the good storage stability and alcohol resistance of the alkylene oxide adduct of bisphenol A, and as a result, it is presumed that it is possible to achieve both storage stability, alcohol resistance, and adhesion.

[0010] <Polyester resin particles> In the present invention, the polyester resin A contained in the polyester resin particles contains a constitutional unit derived from an alcohol component and a constitutional unit derived from a carboxylic acid component from the viewpoint of improving storage stability, adhesion and alcohol resistance. From the same viewpoint as above, the alcohol component contains an alkylene oxide adduct of bisphenol A and 3-methyl-1,5-pentanediol. The polyester resin A is obtained by polycondensing the alcohol component and the carboxylic acid component, that is, the polyester resin A is a polycondensation product of the alcohol component and the carboxylic acid component.

[0011] (Alcohol content) 3-Methyl-1,5-pentanediol is a compound represented by the following formula, and as described above, it is believed to contribute to improving adhesion, storage stability, and alcohol resistance.

[0012] [ka]

[0013] The content of 3-methyl-1,5-pentanediol in the alcohol component constituting polyester resin A is 40 mol% or more, preferably 45 mol% or more, more preferably 50 mol% or more, and even more preferably 55 mol% or more from the viewpoint of improving adhesion, and is 75 mol% or less, preferably 70 mol% or less, more preferably 65 mol% or less, and even more preferably 63 mol% or less from the viewpoint of improving storage stability and alcohol resistance.

[0014] From the viewpoint of improving storage stability and alcohol resistance, the alkylene oxide adduct of bisphenol A is preferably a compound represented by the following general formula (I).

[0015] [ka]

[0016] In the general formula (I), OR 1 , and R 2 Each O is an alkyleneoxy group, preferably each independently is an alkyleneoxy group having 1 to 4 carbon atoms, more preferably an ethyleneoxy group or a propyleneoxy group, and from the viewpoint of improving storage stability, adhesion, and alcohol resistance, still more preferably a propyleneoxy group. x and y correspond to the number of moles of alkylene oxide added. 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. 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 even more preferably 3 or less. x ORs 1 and y R 2 O may be the same or different, but is preferably the same from the viewpoint of improving adhesion. The alkylene oxide adduct of bisphenol A may be used alone or in combination of two or more. From the viewpoint of improving storage stability, adhesion and alcohol resistance, the alkylene oxide adduct of bisphenol A is preferably at least one selected from a propylene oxide adduct of bisphenol A and an ethylene oxide adduct of bisphenol A, and more preferably a propylene oxide adduct of bisphenol A.

[0017] The content of alkylene oxide adduct of bisphenol A in the alcohol component constituting polyester resin A is preferably 25 mol % or more, more preferably 30 mol % or more, even more preferably 35 mol % or more, and still more preferably 37 mol % or more from the viewpoint of improving storage stability and alcohol resistance, and is preferably 60 mol % or less, more preferably 55 mol % or less, even more preferably 50 mol % or less, and still more preferably 45 mol % or less from the viewpoint of improving adhesion.

[0018] The alcohol component constituting the polyester resin A may contain other alcohols in addition to the alkylene oxide adduct of bisphenol A and 3-methyl-1,5-pentanediol, so long as the effects of the present invention are not impaired. Examples of other alcohols include other aliphatic diols and alicyclic diols having a main chain carbon number of 2 to 12 other than 3-methyl-1,5-pentanediol; trihydric or higher polyhydric alcohols; and the like.

[0019] Other aliphatic diols include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 2,3-butanediol, 1,4-butanediol, 1,2-pentanediol, 1,4-pentanediol, 2,4-pentanediol, 1,2-hexanediol, 1,5-hexanediol, 2,5-hexanediol, 1,6-hexanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,12-dodecanediol, and 3,3-dimethyl-1,2-butanediol. Examples of the alicyclic diol include cyclohexanediol, cyclohexanedimethanol, and hydrogenated bisphenol A. Examples of the trihydric or higher polyhydric alcohol include glycerin, pentaerythritol, trimethylolpropane, sorbitol, and sorbitan. The other alcohols may be used alone or in combination of two or more.

[0020] From the viewpoint of improving storage stability, adhesion and alcohol resistance, the total content of the alkylene oxide adduct of bisphenol A and 3-methyl-1,5-pentanediol in the alcohol component constituting polyester resin A is preferably 70 mol % or more, more preferably 80 mol % or more, even more preferably 90 mol % or more, still more preferably 95 mol % or more, and is preferably 100 mol % or less, still more preferably 100 mol %.

[0021] (Carboxylic acid component) Examples of the carboxylic acid component constituting the polyester resin A include dicarboxylic acids and trivalent or higher polyvalent carboxylic acids. In the present invention, the carboxylic acid component includes not only carboxylic acids but also their anhydrides and their alkyl esters having from 1 to 3 carbon atoms. In other words, when only the name of a carboxylic acid is mentioned in this specification, it is understood that the description also includes the anhydrides and alkyl esters of the carboxylic acid having from 1 to 3 carbon atoms. Dicarboxylic acids include aromatic dicarboxylic acids, aliphatic dicarboxylic acids, and alicyclic dicarboxylic acids. Examples of the aromatic dicarboxylic acid include phthalic acid, isophthalic acid, and terephthalic acid. From the viewpoint of improving storage stability, adhesion, and alcohol resistance, isophthalic acid and terephthalic acid are preferred, and terephthalic acid is more preferred. Examples of the aliphatic dicarboxylic acid include fumaric acid, adipic acid, sebacic acid, maleic acid, azelaic acid, succinic acid, and succinic acid substituted with an alkyl group having 1 to 20 carbon atoms or an alkenyl group having 2 to 20 carbon atoms. 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 dodecylsuccinic acid, dodecenylsuccinic acid, and octenylsuccinic acid. From the viewpoint of improving storage stability, adhesion, and alcohol resistance, fumaric acid is preferable. Examples of the alicyclic dicarboxylic acid include cyclohexanedicarboxylic acid. Examples of trivalent or higher polyvalent carboxylic acids include trimellitic acid, 2,5,7-naphthalenetricarboxylic acid, and pyromellitic acid. The carboxylic acid component may be used alone or in combination of two or more.

[0022] Among these, from the viewpoint of improving storage stability, adhesion, and alcohol resistance, the carboxylic acid component constituting polyester resin A preferably contains a dicarboxylic acid, more preferably contains an aromatic dicarboxylic acid, even more preferably contains one or more selected from terephthalic acid and isophthalic acid, and even more preferably contains terephthalic acid. When the carboxylic acid component contains an aromatic dicarboxylic acid, the content of the aromatic dicarboxylic acid in the carboxylic acid component is, from the viewpoint of improving storage stability, adhesion and alcohol resistance, preferably 60 mol% or more, more preferably 70 mol% or more, even more preferably 80 mol% or more, still more preferably 85 mol% or more, still more preferably 90 mol% or more, and is preferably 100 mol% or less, more preferably 97 mol% or less, and still more preferably 95 mol% or less. When the carboxylic acid component contains one or more selected from terephthalic acid and isophthalic acid, the total content of terephthalic acid and isophthalic acid in the carboxylic acid component is, from the viewpoint of improving storage stability, adhesion, and alcohol resistance, preferably 60 mol% or more, more preferably 70 mol% or more, even more preferably 80 mol% or more, still more preferably 85 mol% or more, still more preferably 90 mol% or more, and is preferably 100 mol% or less, more preferably 97 mol% or less, and even more preferably 95 mol% or less. When the carboxylic acid component contains one or more selected from terephthalic acid and isophthalic acid, the content of terephthalic acid in the carboxylic acid component is, from the viewpoint of improving storage stability, adhesion, and alcohol resistance, preferably 60 mol% or more, more preferably 70 mol% or more, even more preferably 80 mol% or more, still more preferably 85 mol% or more, still more preferably 90 mol% or more, and is preferably 100 mol% or less, more preferably 97 mol% or less, and even more preferably 95 mol% or less.

[0023] The carboxylic acid component constituting the polyester resin A preferably contains a trivalent or higher polyvalent carboxylic acid, and more preferably contains trimellitic acid, from the viewpoint of improving storage stability, adhesion, and alcohol resistance. From the viewpoint of improving storage stability, adhesion and alcohol resistance, the content of trivalent or higher polyvalent carboxylic acid in the carboxylic acid component is preferably 3 mol % or more, more preferably 4 mol % or more, even more preferably 5 mol % or more, and is preferably 15 mol % or less, more preferably 10 mol % or less, even more preferably 9 mol % or less, and even more preferably 8 mol % or less.

[0024] From the viewpoint of improving adhesion, 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 constituting the polyester resin A is preferably 0.65 or more, more preferably 0.80 or more, and is preferably 1.2 or less, more preferably 1.1 or less.

[0025] From the viewpoints of improving the dispersion stability of the resin particles in an aqueous medium and improving the storage stability, adhesion and alcohol resistance, the acid value of the polyester resin A is preferably 5 mgKOH / g or more, more preferably 10 mgKOH / g or more, even more preferably 15 mgKOH / g or more, and is preferably 40 mgKOH / g or less, more preferably 35 mgKOH / g or less, even more preferably 30 mgKOH / g or less, and still more preferably 25 mgKOH / g or less. The acid value is measured by the method described in the Examples.

[0026] The number average molecular weight (Mn) of the polyester resin A is, from the viewpoints of improving the dispersion stability of the resin particles in an aqueous medium and improving the storage stability, adhesion and alcohol resistance, preferably 2,500 or more, more preferably 3,000 or more, even more preferably 3,500 or more, and is preferably 6,000 or less, more preferably 5,500 or less, even more preferably 5,000 or less. The number average molecular weight is measured by the method described in the Examples.

[0027] From the viewpoint of improving storage stability, adhesion and alcohol resistance, the glass transition temperature of the polyester resin A is preferably 35°C or higher, more preferably 37°C or higher, even more preferably 40°C or higher, and is preferably 65°C or lower, more preferably 63°C or lower, even more preferably 60°C or lower. The glass transition temperature is measured by using a differential scanning calorimeter, specifically, by the method described in the examples.

[0028] From the viewpoint of improving storage stability, adhesion and alcohol resistance, the softening point of polyester resin A is preferably 70°C or higher, more preferably 80°C or higher, and even more preferably 90°C or higher, and from the same viewpoint, it is preferably 165°C or lower, more preferably 130°C or lower, and even more preferably 120°C or lower. The softening point is measured by the method described in the Examples.

[0029] The polyester resin A may be used alone or in combination of two or more kinds. When two or more kinds of polyester resins A are used in combination, the acid value, number average molecular weight (Mn), glass transition temperature and softening point are measured for each of the mixtures of two or more kinds by the methods described in the examples. The acid value, number average molecular weight, glass transition temperature, and softening point of the polyester resin A can all be obtained as desired by appropriately adjusting the types and blending ratios of the raw material monomers used in the production of the polyester resin A, the polycondensation temperature, and the reaction time.

[0030] The polyester resin A can be obtained by polycondensing the alcohol component and the carboxylic acid component, for example, by polycondensing the alcohol component and the carboxylic acid component in an inert gas atmosphere at a temperature of 120° C. or more and 250° C. or less, using an esterification catalyst as necessary. Examples of the esterification catalyst include tin compounds such as dibutyltin oxide and tin(II) 2-ethylhexanoate, titanium compounds such as titanium diisopropylate bistriethanolamine, etc. Furthermore, an esterification promoter such as 3,4,5-trihydroxybenzoic acid (gallic acid), and a radical polymerization inhibitor such as 4-tert-butylcatechol may be used as necessary.

[0031] In the present invention, when the polyester resin A contains an acid group, it is preferable that the acid group of the polyester resin A is neutralized with a basic compound, from the viewpoints of improving the dispersion stability of the resin particles in an aqueous medium and improving the storage stability, adhesion and alcohol resistance. Examples of the basic compound include metal hydroxides such as lithium hydroxide, sodium hydroxide, and potassium hydroxide; ammonia; and various organic amines, and are preferably at least one selected from sodium hydroxide, potassium hydroxide, and ammonia, and more preferably sodium hydroxide. The basic compound is preferably used as an aqueous solution. The degree of neutralization of polyester resin A, represented by the following formula (1), is preferably 50 mol% or more, more preferably 55 mol% or more, even more preferably 57 mol% or more, and is preferably 100 mol% or less, more preferably 85 mol% or less, even more preferably 80 mol% or less, still more preferably 75 mol% or less, still more preferably 70 mol% or less, and still more preferably 65 mol% or less. Degree of neutralization = {[basic compound added mass (g) / basic compound equivalent (g / mol)] / [[acid value of polyester resin A (mg KOH / g) × mass of polyester resin A (g)] / (56 × 1000 (mg KOH / mol))]} × 100 (1)

[0032] In the present invention, the polyester resin A includes not only unmodified polyester resins but also polyester resins modified to such an extent that their properties are not substantially impaired. Examples of modified polyester resins include polyester resins grafted or blocked with phenol, urethane, epoxy, or the like by the methods described in JP-A-11-133668, JP-A-10-239903, JP-A-8-20636, etc., and composite resins having two or more resin units including a polyester unit.

[0033] Furthermore, the polyester resin particles according to the present invention may contain resins other than the polyester resin A, such as styrene-acrylic copolymers, epoxy resins, polycarbonates, polyurethanes, etc., within the scope of not impairing the effects of the present invention. The polyester resin particles may contain optional components such as reinforcing fillers, such as fibrous substances, and additives, such as antioxidants and antiaging agents, within the scope of not impairing the effects of the present invention. The content of polyester resin A in the polyester resin particles according to the present invention is preferably 70% by mass or more, more preferably 80% by mass or more, even more preferably 90% by mass or more, still more preferably 95% by mass or more, and preferably 100% by mass or less.

[0034] (Production of Polyester Resin Aqueous Dispersion) The polyester resin aqueous dispersion of the present invention is preferably produced by a method of dispersing a resin containing polyester resin A in an aqueous medium. Examples of methods for obtaining the polyester resin aqueous dispersion include a method in which a resin containing polyester resin A is added to an aqueous medium and a dispersion treatment is performed using a disperser or the like, and a method in which an aqueous medium is gradually added to a solution of a resin containing polyester resin A to perform phase inversion emulsification, etc. Among these, the method in which phase inversion emulsification is performed is preferred from the viewpoint of improving storage stability, adhesion, and alcohol resistance.

[0035] A preferred phase inversion emulsification method is to first dissolve a resin containing polyester resin A in an organic solvent to obtain a solution of a resin containing polyester resin A, then add an aqueous medium to the solution to invert the phase, and then remove the organic solvent. As the organic solvent for dissolving the resin including polyester resin A, from the viewpoint of dissolving the resin including polyester resin A and facilitating removal from the emulsion, preferred are dialkyl ketones having an alkyl group having 1 to 3 carbon atoms, such as acetone and methyl ethyl ketone, and more preferred is methyl ethyl ketone. When the polyester resin particles contain multiple types of polyester resin A or resins other than polyester resin A, the multiple types of polyester resin A may be mixed in advance before dissolving in the organic solvent, or polyester resin A may be mixed with the other resin, or these resins may be added simultaneously to an organic solvent and dissolved to obtain a resin solution containing polyester resin A. The mass ratio of the organic solvent to the resin containing polyester resin A [organic solvent / resin] is, from the viewpoint of dissolving the resin and facilitating phase transfer to the aqueous medium and from the viewpoint of further improving the dispersion stability of the resin aqueous dispersion, preferably 30 / 100 or more, more preferably 50 / 100 or more, even more preferably 70 / 100 or more, and is preferably 500 / 100 or less, more preferably 300 / 100 or less, even more preferably 200 / 100 or less, and still more preferably 150 / 100 or less. When the acid group of the polyester resin A is neutralized with a basic compound, it is preferable to obtain a resin solution containing the polyester resin A, and then add an aqueous solution of the basic compound to neutralize the resin solution. The operation of dissolving the resin containing polyester resin A in an organic solvent and the subsequent addition of the aqueous solution of a basic compound are usually carried out at a temperature not higher than the boiling point of the organic solvent.

[0036] The temperature when adding an aqueous medium to a resin solution containing polyester resin A is, from the viewpoint of improving the dispersion stability of the resin aqueous dispersion, preferably 10° C. or higher, more preferably 20° C. or higher, even more preferably 25° C. or higher, and is preferably 80° C. or lower, more preferably 75° C. or lower. From the viewpoint of improving the dispersion stability of the resin aqueous dispersion, the addition rate of the aqueous medium is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, even more preferably 3 parts by mass or more, and even more preferably 5 parts by mass or more, relative to 100 parts by mass of the resin constituting the polyester resin particles, until the phase inversion is completed, and is preferably 100 parts by mass or less, more preferably 50 parts by mass or less, and even more preferably 30 parts by mass or less. There is no restriction on the addition rate of the aqueous medium after the phase inversion and the polyester resin particles are obtained. From the viewpoint of improving the productivity of the resin aqueous dispersion, the amount of the aqueous medium added is preferably 50 parts by mass or more, more preferably 100 parts by mass or more, and even more preferably 200 parts by mass or more, relative to 100 parts by mass of the resin constituting the polyester resin particles, and is preferably 900 parts by mass or less, more preferably 500 parts by mass or less, and even more preferably 400 parts by mass or less.

[0037] After the phase inversion emulsification, from the viewpoint of improving the dispersion stability of the resin aqueous dispersion, it is preferable to remove the organic solvent from the dispersion obtained by the phase inversion emulsification. The method for removing the organic solvent is not particularly limited, and any method can be used. The obtained polyester resin aqueous dispersion is preferably filtered through a wire mesh or the like to remove coarse particles, etc. When the organic solvent is removed, water is also reduced by azeotropy together with the organic solvent, so that it is preferable to add water to adjust the solid content concentration. From the viewpoint of improving adhesion, the solid content concentration of the polyester resin aqueous dispersion of the present invention is preferably 5% by mass or more, more preferably 10% by mass or more, even more preferably 20% by mass or more, and is preferably 50% by mass or less, more preferably 45% by mass or less, even more preferably 40% by mass or less. The solid content concentration of the aqueous dispersion is measured by the method described in the Examples. From the viewpoint of improving adhesion, the pH of the polyester resin aqueous dispersion of the present invention is preferably 6.0 or more, more preferably 6.5 or more, and even more preferably 6.8 or more, and is preferably 9.0 or less, more preferably 8.0 or less, and even more preferably 7.5 or less. The pH of the aqueous dispersion is measured by the same method as that for measuring the pH of the water-based ink described in the Examples.

[0038] From the viewpoint of improving storage stability, adhesion and alcohol resistance, the volume average particle diameter Dv of the polyester resin particles in the polyester resin aqueous dispersion of the present invention is preferably 25 nm or more, more preferably 28 nm or more, even more preferably 40 nm or more, still more preferably 45 nm or more, still more preferably 50 nm or more, and preferably 500 nm or less, more preferably 200 nm or less, still more preferably 100 nm or less, still more preferably 80 nm or less. The volume average particle diameter Dv is measured by the method described in the Examples.

[0039] [Water-based ink] The polyester resin aqueous dispersion of the present invention is preferably used in a water-based ink from the viewpoint of improving storage stability, adhesion and alcohol resistance. The water-based ink of the present invention is not particularly limited in hue and may be either a transparent ink not containing a colorant or an ink containing a colorant, but from the viewpoint of improving storage stability, adhesion and alcohol resistance, it preferably contains the polyester resin aqueous dispersion and a colorant. This allows the resin constituting the polyester resin particles in the water-based ink to act as a fixing agent for the colorant when forming an ink coating, thereby improving adhesion to a resin printing medium.

[0040] <Coloring agent> The colorant may be either a pigment or a dye. The colorant used in the present invention includes pigments, hydrophobic dyes, water-soluble dyes (acid dyes, reactive dyes, direct dyes, etc.), etc. Among these, from the viewpoint of improving the storage stability, adhesion, and alcohol resistance of the water-based ink, preferably one or more selected from pigments and hydrophobic dyes, more preferably pigments.

[0041] The pigment may be either an inorganic pigment or an organic pigment. Examples of inorganic pigments include carbon black and metal oxides, and when used in black ink, carbon black is preferred. Examples of the organic pigment include azo pigments, diazo pigments, phthalocyanine pigments, quinacridone pigments, isoindolinone pigments, dioxazine pigments, perylene pigments, perinone pigments, thioindigo pigments, anthraquinone pigments, and quinophthalone pigments. Among these, phthalocyanine pigments are preferred, and copper phthalocyanine is more preferred. The hue is not particularly limited, and any chromatic pigment such as yellow, magenta, cyan, blue, red, orange, green, etc. can be used. The organic pigment is preferably one or more product numbers selected from the group consisting of CI Pigment Yellow, CI Pigment Red, CI Pigment Orange, CI Pigment Violet, CI Pigment Blue, and CI Pigment Green. As the pigment, a so-called self-dispersing pigment can also be used. A self-dispersing pigment is a pigment that can be dispersed in an aqueous medium without using a surfactant or resin by bonding one or more types of hydrophilic functional groups (anionic hydrophilic groups such as a carboxy group or a sulfonic acid group; cationic hydrophilic groups such as a quaternary ammonium group) to the surface of the pigment directly or via other atomic groups.

[0042] The hydrophobic dye is a dye that preferably has a solubility of less than 6% by mass in 100 g of water (at 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 desired ratio.

[0043] From the viewpoint of improving the storage stability, adhesion, and alcohol resistance of the water-based ink, the colorant is preferably in the form of colorant particles stabilized using a surfactant or a polymer dispersant, and more preferably in the form of colorant particles dispersed using a polymer dispersant. Examples of the polymer dispersant include condensation resins such as polyester resins and polyurethane resins; and vinyl resins such as acrylic resins, styrene resins, styrene-acrylic resins, and acrylic silicone resins. The polymer dispersant may be used alone or in combination of two or more. Among them, the polymer dispersant is preferably one or more selected from polyester resins and vinyl resins, more preferably polyester resins, from the viewpoint of improving the storage stability, adhesion, and alcohol resistance of the water-based ink. The polyester resin used as the polymer dispersant may be the above-mentioned polyester resin A. However, from the viewpoint of improving the storage stability, adhesion, and alcohol resistance of the water-based ink, it is preferable to use a polyester resin B different from the polyester resin A.

[0044] The polyester resin B is obtained by polycondensing an alcohol component and a carboxylic acid component, that is, the polyester resin B is a polycondensation product of an alcohol component and a carboxylic acid component. The alcohol component constituting the polyester resin B preferably contains an alkylene oxide adduct of bisphenol A from the viewpoint of improving the storage stability, adhesion and alcohol resistance of the water-based ink. The alkylene oxide adduct of bisphenol A is preferably a compound represented by the general formula (I) above, more preferably one or more selected from a propylene oxide adduct of bisphenol A and an ethylene oxide adduct of bisphenol A, and even more preferably a propylene oxide adduct of bisphenol A. The alcohol component may contain an alcohol component other than the alkylene oxide adduct of bisphenol A. Examples of the other alcohol components include aliphatic diols having 2 to 12 carbon atoms in the main chain other than the alkylene oxide adducts of bisphenol A, aromatic diols other than the alkylene oxide adducts of bisphenol A, and diols such as alicyclic diols; and polyhydric alcohols having a valence of three or more. The above alcohol components can be used alone or in combination of two or more. From the viewpoint of improving the storage stability, adhesion, and alcohol resistance of the water-based ink, the content of the alkylene oxide adduct of bisphenol A in the alcohol component that constitutes polyester resin B is preferably 80 mol % or more, more preferably 85 mol % or more, even more preferably 90 mol % or more, still more preferably 95 mol % or more, and is 100 mol % or less, preferably 100 mol %.

[0045] Examples of the carboxylic acid component constituting the polyester resin B include the above-mentioned dicarboxylic acids and trivalent or higher polyvalent carboxylic acids. Among them, from the viewpoint of improving the storage stability, adhesion and alcohol resistance of the water-based ink, it preferably contains a dicarboxylic acid, more preferably contains one or more selected from aromatic dicarboxylic acids and aliphatic dicarboxylic acids, and further preferably contains terephthalic acid and fumaric acid. The content of aromatic dicarboxylic acid in the carboxylic acid component constituting polyester resin B is preferably 10 mol % or more, more preferably 20 mol % or more, even more preferably 30 mol % or more, still more preferably 40 mol % or more, even more preferably 50 mol % or more, and is preferably 70 mol % or less, more preferably 65 mol % or less, and even more preferably 60 mol % or less. The content of aliphatic dicarboxylic acid in the carboxylic acid component constituting polyester resin B is preferably 5 mol % or more, more preferably 10 mol % or more, even more preferably 15 mol % or more, still more preferably 20 mol % or more, and is preferably 40 mol % or less, more preferably 35 mol % or less, and even more preferably 30 mol % or less.

[0046] The carboxylic acid component constituting the polyester resin B preferably contains a polyvalent carboxylic acid having three or more valences, from the viewpoint of improving the storage stability, adhesion and alcohol resistance of the water-based ink. As the trivalent or higher polyvalent carboxylic acid, the above-mentioned trivalent aromatic carboxylic acid is more preferable, and trimellitic acid is further preferable. From the viewpoint of improving the storage stability, adhesion, and alcohol resistance of the water-based ink, the content of trivalent or higher polyvalent carboxylic acid in the carboxylic acid component constituting the polyester resin B is preferably 3 mol % or more, more preferably 5 mol % or more, even more preferably 7 mol % or more, still more preferably 10 mol % or more, and is preferably 20 mol % or less, more preferably 17 mol % or less, even more preferably 15 mol % or less, and still more preferably 13 mol % or less. The above carboxylic acid components can be used alone or in combination of two or more.

[0047] 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 of polyester resin B is preferably 0.65 or more, more preferably 0.70 or more, and is preferably 1.2 or less, more preferably 1.1 or less.

[0048] The polyester resin B can be produced by polycondensation reaction of the carboxylic acid component and the alcohol component in the same manner as the polyester resin A. For example, the polyester resin B can be produced by polycondensation of the alcohol component and the carboxylic acid component in an inert gas atmosphere at a temperature of 120° C. or higher and 250° C. or lower, using the above-mentioned esterification catalyst, esterification promoter, and polymerization inhibitor as necessary.

[0049] From the viewpoint of improving the storage stability, adhesion and alcohol resistance of the water-based ink, the acid value of polyester resin B is preferably 10 mgKOH / g or more, more preferably 20 mgKOH / g or more, even more preferably 25 mgKOH / g or more, and is preferably 40 mgKOH / g or less, more preferably 37 mgKOH / g or less, even more preferably 35 mgKOH / g or less. From the viewpoint of improving the storage stability, adhesion, and alcohol resistance of the water-based ink, the glass transition temperature of polyester resin B is preferably 50° C. or more, more preferably 60° C. or more, even more preferably 70° C. or more, and is preferably 100° C. or less, more preferably 90° C. or less, even more preferably 80° C. or less. From the viewpoint of improving the storage stability, adhesion, and alcohol resistance of the water-based ink, the softening point of polyester resin B is preferably 100°C or higher, more preferably 110°C or higher, even more preferably 120°C or higher, and is preferably 150°C or lower, more preferably 140°C or lower, and even more preferably 130°C or lower. The acid value, glass transition temperature, and softening point of the polyester resin B can be measured by the method described in the examples. The means for adjusting the physical properties of polyester resin B to fall within the above range is not particularly limited. For example, the physical properties can be appropriately adjusted by adjusting the types and ratio of raw material monomers, as well as production conditions such as reaction temperature, reaction time, and cooling rate. When two or more resins are mixed and used as polyester resin B, the acid value, glass transition temperature and softening point are values ​​obtained by measuring the mixture of two or more resins by the method described in the examples.

[0050] The colorant particles dispersed in a polymer dispersant can be produced, for example, by a method in which a colorant mixture containing polyester resin B, an organic solvent, a colorant, water, and, as necessary, a neutralizing agent, a surfactant, and the like are subjected to a dispersion treatment to obtain a dispersion of colorant particles dispersed in a polymer dispersant, and then the organic solvent is removed from the dispersion to obtain an aqueous dispersion of colorant particles dispersed in a polymer dispersant. At least a part of the acid groups of the polyester resin B is preferably neutralized with a basic compound. As the basic compound used for neutralization, the same compounds as those exemplified for the polyester resin A can be used. From the viewpoint of promoting sufficient and uniform neutralization, the basic compound is preferably used as an aqueous solution. The degree of neutralization of polyester resin B is preferably 60 mol % or more, more preferably 70 mol % or more, even more preferably 75 mol % or more, and preferably 100 mol % or less, more preferably 95 mol % or less, even more preferably 90 mol % or less. The degree of neutralization of the polyester resin B is represented by the following formula (2). When the degree of neutralization exceeds 100 mol %, this means that the neutralizing agent is in excess of the acid groups of polyester resin B, and the degree of neutralization of polyester resin B in this case is considered to be 100 mol %. Degree of neutralization = {[basic compound added mass (g) / basic compound equivalent (g / mol)] / [[acid value of polyester resin B (mg KOH / g) x mass of polyester resin B (g)] / (56 x 1000 (mg KOH / mol))]} x 100 (2)

[0051] In the dispersion treatment of the colorant mixture, the pigment particles can be atomized to a desired particle size only by main dispersion using shear stress. However, from the viewpoint of obtaining a uniform aqueous pigment dispersion, it is preferable to pre-disperse the colorant mixture and then further carry out main dispersion. As a dispersing machine used for preliminary dispersion, a commonly used mixing and stirring device such as an anchor blade or a dispersing blade can be used. Examples of means for applying shear stress used in the present dispersion include kneaders such as roll mills and kneaders, high-pressure homogenizers such as microfluidizers, and media-type dispersers such as paint shakers and bead mills. Among these, it is preferable to use a high-pressure homogenizer from the viewpoint of reducing the particle size of the pigment. When a dispersion process is performed using a high-pressure homogenizer, the colorant can be controlled to have a desired particle size by controlling the processing pressure and the number of passes, and the volume average particle size Dv of the colorant particles, which will be described later, can also be adjusted. When the colorant mixture contains an organic solvent, the organic solvent can be removed by a known method to obtain an aqueous dispersion. It is preferable that the organic solvent in the obtained aqueous dispersion is substantially removed, but it may remain as long as it does not impair the object of the present invention. The amount of the residual organic solvent is preferably 0.1% by mass or less, more preferably 0.01% by mass or less. The resulting aqueous dispersion is preferably filtered through a wire mesh or the like to remove coarse particles and the like. From the viewpoint of improving the productivity and storage stability of the aqueous dispersion, the obtained aqueous dispersion may further contain various additives, such as an organic solvent, a preservative, and an antifungal agent, which are optionally added to the aqueous ink described below.

[0052] From the viewpoint of improving the productivity and storage stability of the aqueous dispersion, the solid content concentration of the aqueous dispersion of the colorant particles dispersed with the polymer dispersant is preferably 5% by mass or more, more preferably 10% by mass or more, even more preferably 15% by mass or more, and is preferably 40% by mass or less, more preferably 30% by mass or less, even more preferably 25% by mass or less. The solid content concentration of the aqueous dispersion is measured by the method described in the Examples.

[0053] The volume average particle diameter Dv of the colorant particles dispersed with the polymer dispersant in the aqueous dispersion is preferably 40 nm or more, more preferably 50 nm or more, even more preferably 100 nm or more, and is preferably 200 nm or less, more preferably 150 nm or less, and even more preferably 130 nm or less, from the viewpoint of improving the dispersion stability of the aqueous ink and improving the storage stability, adhesion and alcohol resistance of the aqueous ink. The volume average particle diameter Dv is measured by the method described in the Examples.

[0054] (Water-based ink manufacturing) The water-based ink of the present invention can be produced, for example, by mixing the water dispersion of the polyester resin particles and the water dispersion of colorant particles dispersed in a polymer dispersant. For the mixing, various stirring devices can be used. The water-based ink of the present invention can be obtained by adding various additives, such as organic solvents, moisturizers, wetting agents, penetrants, surfactants, viscosity adjusters, defoamers, preservatives, antifungal agents, rust inhibitors, pH adjusters, antioxidants, and ultraviolet absorbers, as necessary, and further performing a filtration treatment using a filter or the like.

[0055] From the viewpoint of improving the storage stability, adhesion and alcohol resistance of the water-based ink of the present invention, it is preferable that the water-based ink further contains an organic solvent, which preferably has a boiling point of 90° C. or more and 250° C. or less, from the same viewpoint as above. Examples of the organic solvent include polyhydric alcohols, polyhydric alcohol alkyl ethers, nitrogen-containing heterocyclic compounds, amides, amines, sulfur-containing compounds, etc. Among these, one or more selected from polyhydric alcohols and polyhydric alcohol alkyl ethers are preferred, one or more selected from ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, glycerin, trimethylolpropane, diethylene glycol monoisobutyl ether, and diethylene glycol diethyl ether are more preferred, and one or more selected from propylene glycol and diethylene glycol monoisobutyl ether are even more preferred.

[0056] The water-based ink of the present invention preferably further contains a surfactant from the viewpoint of improving the storage stability, adhesion and alcohol resistance of the water-based ink. Examples of the surfactant include nonionic surfactants, anionic surfactants, amphoteric surfactants, etc. Among these, nonionic surfactants are preferred. Examples of the nonionic surfactant include acetylene glycol surfactants, polyoxyalkylene alkyl ether surfactants, polyhydric alcohol surfactants, fatty acid alkanolamides, nonionic silicone surfactants, nonionic fluorine surfactants, etc. Among these, one or more selected from acetylene glycol surfactants, polyoxyalkylene alkyl ether surfactants, and nonionic silicone surfactants are preferred, and acetylene glycol surfactants are more preferred. The surfactants may be used alone or in combination of two or more.

[0057] From the viewpoint of improving the storage stability, adhesion, and alcohol resistance of the water-based ink, the content of polyester resin particles in the water-based ink is preferably 1% by mass or more, more preferably 2% by mass or more, even more preferably 3% by mass or more, and is preferably 30% by mass or less, more preferably 20% by mass or less, even more preferably 10% by mass or less, and even more preferably 7% by mass or less. From the viewpoint of improving the storage stability, adhesion, and alcohol resistance of the water-based ink, and from the viewpoint of print density, the content of the colorant in the water-based ink is preferably 1% by mass or more, more preferably 2% by mass or more, even more preferably 3% by mass or more, and is preferably 20% by mass or less, more preferably 10% by mass or less, even more preferably 7% by mass or less, and still more preferably 5% by mass or less.

[0058] The mass ratio of the content of the colorant to the polyester resin particles in the water-based ink [colorant / polyester resin particles] is, from the viewpoint of improving the dispersion stability of the colorant particles, improving the storage stability, adhesion and alcohol resistance of the water-based ink, and from the viewpoint of print density, preferably 10 / 90 or more, more preferably 20 / 80 or more, even more preferably 30 / 70 or more, still more preferably 40 / 60 or more, and is preferably 90 / 10 or less, more preferably 80 / 20 or less, even more preferably 70 / 30 or less, still more preferably 60 / 40 or less, and still more preferably 50 / 50 or less.

[0059] When the colorant is in the form of colorant particles dispersed with a polymer dispersant, the mass ratio of the content of the colorant to the polymer dispersant in the water-based ink [colorant / polymer dispersant] is, from the viewpoints of improving the dispersion stability of the colorant particles and improving the storage stability, adhesion and alcohol resistance of the water-based ink, and of printing density, preferably 50 / 50 or more, more preferably 60 / 40 or more, even more preferably 65 / 35 or more, and is preferably 90 / 10 or less, more preferably 80 / 20 or less, even more preferably 75 / 25 or less.

[0060] When the water-based ink further contains an organic solvent, from the viewpoint of improving the dispersion stability of the colorant particles and improving the storage stability, adhesion and alcohol resistance of the water-based ink, the content of the organic solvent in the water-based ink is preferably 5% by mass or more, more preferably 10% by mass or more, even more preferably 20% by mass or more, still more preferably 25% by mass or more, and is preferably 45% by mass or less, more preferably 40% by mass or less, and even more preferably 35% by mass or less.

[0061] When the water-based ink further contains a surfactant, from the viewpoints of improving the dispersion stability of the colorant particles and improving the storage stability, adhesion and alcohol resistance of the water-based ink, the content of the surfactant in the water-based ink is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, and is preferably 5% by mass or less, more preferably 2% by mass or less.

[0062] From the viewpoint of improving the storage stability, adhesion, and alcohol resistance of the water-based ink, the content of water in the water-based ink is preferably 40% by mass or more, more preferably 50% by mass or more, even more preferably 55% by mass or more, and is preferably 90% by mass or less, more preferably 80% by mass or less, even more preferably 70% by mass or less.

[0063] From the viewpoint of storage stability, the viscosity of the water-based ink of the present invention at 32°C is preferably 4.5 mPa·s or more, more preferably 5.0 mPa·s or more, even more preferably 5.2 mPa·s or more, and preferably 6.5 mPa·s or less, more preferably 6.0 mPa·s or less, even more preferably 5.8 mPa·s or less. The viscosity of the water-based ink can be measured using an E-type viscometer. From the viewpoint of storage stability, the pH of the water-based ink at 25° C. is preferably 7.0 or more, more preferably 7.2 or more, and even more preferably 7.5 or more. From the viewpoint of member resistance and skin irritation, the pH is preferably 11 or less, more preferably 10 or less, and even more preferably 9.5 or less. The pH of the water-based ink can be measured by the method described in the Examples.

[0064] The water-based ink of the present invention can be suitably used as a flexographic printing ink, a gravure printing ink, or an inkjet recording ink, and is particularly preferably used as an inkjet recording ink. The water-based ink of the present invention can be loaded into a known inkjet recording device and ejected as ink droplets onto a printing medium to obtain a printed matter on which images, characters, etc. are recorded. Ink jet recording apparatuses include thermal and piezoelectric types, and the water-based ink of the present invention is more preferably used as a water-based ink for piezoelectric type ink jet recording.

[0065] Examples of the printing medium to be used include resin printing media such as highly water-absorbent plain paper, low water-absorbent coated paper, and non-water-absorbent resin film. Examples of coated paper include general-purpose glossy paper and multicolor foam gloss paper. Among these, resin printing media are preferred from the viewpoints of adhesion and alcohol resistance. Examples of commonly available resin films include Transparent PVC RE-137 (manufactured by Mimaki Engineering Co., Ltd., polyvinyl chloride), PVC80B P (manufactured by Lintec Corporation, polyvinyl chloride), DGS-210WH (manufactured by Roland DG Corporation, vinyl chloride), Lumirror T60 (manufactured by Toray Industries, Inc., polyester), KYNAS KEE70CA (manufactured by Lintec Corporation, polyethylene), YUPO SG90 PAT1 (manufactured by Lintec Corporation, polypropylene), FOR, FOA (both manufactured by Futamura Chemical Co., Ltd., polypropylene), Bonyl RX (manufactured by Kohjin Film & Chemicals Co., Ltd., nylon), and Emblem ONBC (manufactured by Unitika Ltd., nylon). The resin printing medium is preferably one or more selected from polyvinyl chloride film, polyester film, polypropylene film, and polyethylene film, more preferably one or more selected from polyvinyl chloride film and polyester film, and even more preferably polyvinyl chloride film. The resin film may be a corona-treated substrate. When the water-based ink of the present invention is used in an inkjet recording method, it is preferable to apply the water-based ink to a resin print medium by the inkjet recording method, and then heat the resin print medium to which the water-based ink is applied to dry the printed surface. The drying temperature of the printed surface is preferably 40° C. or higher, more preferably 50° C. or higher, and preferably 100° C. or lower, more preferably 90° C. or lower, and further preferably 70° C. or lower. EXAMPLES

[0066] In the following examples, each physical property was measured by the following methods.

[0067] [Acid value of polyester resin] The acid value of the polyester resin was measured based on the method of JIS K0070: 1992. However, the measurement solvent was changed from the mixed solvent of ethanol and ether specified in JIS K0070: 1992 to a mixed solvent of acetone and toluene (acetone:toluene = 1:1 (volume ratio)).

[0068] [Number average molecular weight (Mn) of polyester resin] The number average molecular weight (Mn) was determined by gel permeation chromatography (GPC) according to the following method. (1) Preparation of sample solution The sample was dissolved in tetrahydrofuran at 40° C. to a concentration of 0.5 g / 100 mL. Next, this solution was filtered using a PTFE-type membrane filter "DISMIC-25JP" (manufactured by Toyo Roshi Kaisha, Ltd.) with a pore size of 0.20 μm to remove insoluble components, thereby obtaining a sample solution. (2) Molecular weight measurement Using the following measuring device and analytical column, tetrahydrofuran was used as the eluent at a flow rate of 1 mL per minute, and the column was stabilized in a thermostatic bath at 40°C. 100 μL of the sample solution was injected into the column and the measurement was performed. The molecular weight of the sample was calculated based on a calibration curve prepared in advance. Measuring device: HLC-8220GPC (manufactured by Tosoh Corporation) Analytical column: TSKgel GMHXL + TSKgel G3000HXL (manufactured by Tosoh Corporation) For the calibration curve, several types of monodisperse polystyrene (A-500 (5.0 × 10 2 ), A-1000(1.01×10 3 ), A-2500(2.63×10 3 ), A-5000(5.97×10 3 ), F-1(1.02×10 4 ), F-2(1.81×10 4 ), F-4(3.97×10 4 ), F-10(9.64×10 4 ), F-20(1.90×10 5 ), F-40(4.27×10 5 ), F-80(7.06×10 5 ), F-128(1.09×10 6 )) was used as a standard sample. The numbers in parentheses indicate the molecular weight.

[0069] [Softening point of polyester resin] Using a flow tester "CFT-500D" (Shimadzu Corporation), 1 g of sample was heated at a temperature increase rate of 6°C / min, while applying a load of 1.96 MPa with the plunger, and extruding the sample from a nozzle with a diameter of 1 mm and a length of 1 mm. The plunger descent amount 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.

[0070] [Glass transition temperature of polyester resin] Using a differential scanning calorimeter "Q-100" (manufactured by TA Instruments Japan), 0.01 to 0.02 g of sample was weighed into an aluminum pan, heated from room temperature (20°C) to 200°C at a heating rate of 10°C / min, and cooled from that temperature to 0°C at a heating rate of 10°C / min. The sample was then heated to 180°C at a heating rate of 10°C / min, and the glass transition temperature was determined as the temperature at the intersection of the extension of the baseline below the highest endothermic peak temperature and the tangent line showing the maximum slope from the rising part of the peak to the top of the peak.

[0071] [Volume average particle size Dv of polyester resin particles and colorant particles] The volume average particle diameter Dv was measured using the following measuring device under the following measuring conditions. Measurement equipment: Zeta potential / particle size measurement system "ELSZ-2" (Otsuka Electronics Co., Ltd.) Measurement conditions: Cumulant analysis method. The particle concentration to be measured is about 5×10 -3 The dispersion liquid diluted with water to a mass % was placed in a measurement cell, and measurements were taken at a temperature of 25°C, with an angle of 90° between the incident light and the detector, 100 accumulations, and the refractive index of water (1.333) entered as the refractive index of the dispersion solvent.

[0072] [Solids concentration of polyester resin aqueous dispersion] Using an infrared moisture meter "FD-230" (Kett Electric Laboratory Co., Ltd.), 5 g of the measurement sample was dried at a drying temperature of 150°C and measurement mode 96 (monitoring time 2.5 minutes / fluctuation range 0.05%) to measure the moisture content (mass%) of the aqueous dispersion. The solid content was calculated according to the following formula. Solid concentration (mass%) = 100-moisture (mass%)

[0073] [Solids Concentration of Water Dispersion of Colorant Particles] 10.0 g of sodium sulfate was weighed out in a 30 mL polypropylene container (inner diameter 40 mm, height 30 mm) that had been brought to a constant weight in a desiccator, and about 1.0 g of the sample was added thereto and mixed, and then accurately weighed. The mixture was then maintained at 105°C for 2 hours to remove volatile matter, and was then left in the desiccator for 15 minutes, after which the mass was measured. The mass of the sample after removing the volatile matter was taken as the solid content, and divided by the mass of the sample added to obtain the solid content concentration.

[0074] [pH of water-based ink] The measurement was performed at 25° C. using a pH meter "HM-20P" (manufactured by DKK-TOA Corporation) after calibration with standard buffer solutions of pH 6.86 and pH 9.18 (manufactured by DKK-TOA Corporation).

[0075] Production Examples 1-1 to 1-5, 1-7 to 1-10 (Production of Polyester Resins A1 to A5, A7, AC1 to AC3) The raw material monomers other than trimellitic anhydride, the esterification catalyst and the esterification promoter shown in Table 1 were placed in a 10L four-neck flask equipped with a nitrogen inlet tube, a stirrer and a thermocouple, and the temperature was raised to 235°C under a nitrogen atmosphere, and polycondensation was carried out at 235°C for 6 hours. Then, the temperature was lowered to 210°C, and the trimellitic anhydride shown in Table 1 was added, and the reaction was carried out at 210°C for 1 hour. Then, the reaction was carried out at 210°C and a reduced pressure of 10 kPa until the softening point shown in Table 1 was reached, to obtain polyester resins A1 to A5, A7, and AC1 to AC3. Various physical properties of the obtained resins are shown in Table 1.

[0076] Production Example 1-6 (Production of Polyester Resin A6) The raw material monomers other than fumaric acid and trimellitic anhydride, the esterification catalyst and the esterification promoter shown in Table 1 were placed in a 10L four-neck flask equipped with a nitrogen inlet tube, a stirrer and a thermocouple, and the temperature was raised to 235°C under a nitrogen atmosphere, and then polycondensed at 235°C for 6 hours. Then, after lowering the temperature to 210°C, fumaric acid, trimellitic anhydride and 4-tert-butylcatechol as a polymerization inhibitor shown in Table 1 were added and reacted at 210°C for 1 hour. Then, the reaction was continued at 210°C and under a reduced pressure of 10 kPa until the softening point shown in Table 1 was reached, to obtain polyester resin A6. The physical properties of the obtained resin are shown in Table 1.

[0077] [Table 1]

[0078] Examples 1-1 to 1-8 and Comparative Examples 1-1 to 1-3 (Production of Polyester Resin Aqueous Dispersions E1 to E8 and EC1 to EC3) The polyester resin of the type and amount shown in Table 2 was placed in a 1L four-neck flask equipped with a nitrogen inlet tube, a reflux condenser, a stirrer "Three One Motor BL300" (manufactured by Shinto Scientific Co., Ltd.) and a thermocouple, and mixed with 200g of methyl ethyl ketone at 30°C to dissolve the resin. Next, a 48% by mass aqueous solution of sodium hydroxide shown in Table 2 was added so that the degree of neutralization of the polyester resin was 60 mol%, and after stirring for 30 minutes, the entire amount of ion-exchanged water shown in Table 2 was dropped at a rate of 20mL / min at 30°C while stirring. Next, the temperature was raised to 60°C, and the pressure was gradually reduced from 80kPa to 30kPa to distill off the methyl ethyl ketone, and further distill off some of the water. After cooling to 25°C, the mixture was filtered through a 150-mesh wire net and adjusted to a solid content of 30% by mass with ion-exchanged water to obtain an aqueous dispersion of polyester resin containing polyester resin particles having the properties shown in Table 2. The following evaluations were performed using the obtained aqueous dispersion. The results are shown in Table 2.

[0079] [Evaluation of storage stability of polyester resin aqueous dispersion] Each polyester resin aqueous dispersion obtained in the examples and comparative examples was stored in a sealed container in a thermostatic chamber at 60°C, and after 45 days, it was taken out and the volume average particle size (Dv') after storage was measured by the above-mentioned method. The rate of change in the average particle size after storage at 60°C for 45 days was calculated by the following formula (rounded down to the nearest whole number), and the storage stability was evaluated according to the following evaluation criteria. Rate of change in average particle size (%) = [[Volume average particle size after storage (Dv') / Volume average particle size before storage (Dv)] - 1] x 100 (Evaluation Criteria) A: The absolute value of the rate of change in average particle size is less than 5%. B: The absolute value of the rate of change in average particle size is 5% or more and less than 15%. C: The absolute value of the average particle size change rate is 15% or more and less than 30%. D: The absolute value of the rate of change in average particle size is 30% or more and less than 50%. E: The absolute value of the rate of change in average particle diameter is 50% or more, or the aqueous dispersion has lost fluidity and is not in a state where the volume average particle diameter Dv' can be measured.

[0080] [Evaluation of PVC adhesion of polyester resin aqueous dispersion] 1.67 g of each polyester resin aqueous dispersion obtained in the examples and comparative examples, 1.0 g of propylene glycol, 0.1 g of acetylene glycol surfactant "Olfine E1010" (manufactured by Nissin Chemical Industry Co., Ltd.), and 7.23 g of ion-exchanged water were mixed and stirred with a magnetic stirrer at room temperature for 15 minutes to obtain an aqueous dispersion for adhesion evaluation. The obtained aqueous dispersion was applied to a PVC film "Transparent PVC RE-137" (manufactured by Mimaki Engineering Co., Ltd.) using a bar coater No. 6 and a tabletop coater TC-1 (manufactured by Mitsui Electric Seiki Co., Ltd.) at a speed of 6 m / min, and then dried for 3 minutes in a dryer at 60 ° C. to form a coating film. Next, 11 cuts (1 mm apart) were made vertically and horizontally on the formed coating film surface using a cutter knife to reach the PVC film base, and a grid of 100 squares was created. Next, "Cellotape (registered trademark) CT15" (manufactured by Nichiban Co., Ltd.) was applied to the grid, and the tape was peeled off at an angle of 90° at a speed of 10 cm / sec, and the number of squares that did not peel off was visually confirmed. Table 2 shows the number of squares that did not peel off per 100 squares. The greater the number of squares that did not peel off, the better the adhesion to the PVC film.

[0081] [Table 2]

[0082] It can be seen from Table 2 that the polyester resin aqueous dispersions of Examples 1-1 to 1-8 are superior in storage stability and adhesion to PVC films as compared with the polyester resin aqueous dispersions of Comparative Examples 1-1 to 1-3. In Comparative Example 1-1, the storage stability is poor because the alcohol component constituting the polyester resin was changed from 3-methyl-1,5-pentanediol to 1,5-pentanediol, which is a straight-chain aliphatic alcohol. In Comparative Example 1-2, the content of 3-methyl-1,5-pentanediol in the alcohol component constituting the polyester resin is less than 40 mol %, and therefore the adhesion to the PVC film is poor. In Comparative Example 1-3, the content of 3-methyl-1,5-pentanediol in the alcohol component constituting the polyester resin exceeds 75 mol %, and therefore the storage stability is poor.

[0083] Examples 2-1 to 2-8 and Comparative Examples 2-1 to 2-3 (Production of Water-Based Inks I-1 to I-8 and IC-1 to IC-3) To a 100 mL screw tube, 25.0 g of propylene glycol, 5.0 g of diethylene glycol monoisobutyl ether, 1.0 g of the acetylene glycol surfactant "Olfine E1010" (manufactured by Nissin Chemical Industry Co., Ltd.), and 22.1 g of ion-exchanged water were added, and the mixture was stirred at room temperature for 15 minutes using a magnetic stirrer to obtain a mixed solution. Next, 28.6 g of an aqueous dispersion (P1) of pigment particles using a cyan pigment (CI Pigment Blue 15:3) as a colorant obtained in the following Production Example 2 (4.0 parts by mass as the content of the colorant relative to 100 parts by mass of the total amount of the aqueous ink) was added and mixed with the mixed solution while stirring with a magnetic stirrer, and 18.3 g of each aqueous dispersion of polyester resin shown in Table 3 (5.5 parts by mass as the solid content relative to 100 parts by mass of the total amount of the aqueous ink) was added dropwise with a dropper while stirring and mixing. Next, the mixture was filtered with a filter "Minisart" (manufactured by Sartorius Stedim Biotech) with a pore size of 5.0 μm to obtain each aqueous ink. The following evaluations were performed using the obtained aqueous ink. The results are shown in Table 3.

[0084] Production Example 2 (Production of Water Dispersion P1 of Pigment Particles) (1) Production of polyester resin B1 4828g of propylene oxide (2.2) adduct of 2,2-bis(4-hydroxyphenyl)propane, 1374g of terephthalic acid, 35g of tin(II) 2-ethylhexanoate as an esterification catalyst, and 3.5g of gallic acid as an esterification promoter were placed in a 10L four-neck flask equipped with a nitrogen inlet tube, a stirrer, and a thermocouple, and the mixture was heated to 235°C under a nitrogen atmosphere, and then polycondensed at 235°C for 5 hours. Then, after lowering the temperature to 180°C, 480g of fumaric acid, 318g of trimellitic anhydride, and 3.5g of 4-tert-butylcatechol as a polymerization inhibitor were added, and the mixture was heated stepwise to 210°C over 3 hours to react. Then, the mixture was reacted at 210°C under a reduced pressure of 66.7kPa for 3 hours to obtain polyester resin B1. The resulting polyester resin B1 had an acid value of 30 mgKOH / g, a glass transition temperature of 72.2°C and a softening point of 123.5°C.

[0085] (2) Preparation of aqueous dispersion P1 of pigment particles 42.7 g of polyester resin (B1) was dissolved in 142.7 g of methyl ethyl ketone as a polymer dispersant, and 1.6 g of 48% by mass aqueous sodium hydroxide solution as a neutralizing agent and 240 g of ion-exchanged water were added, and the mixture was stirred and mixed for 15 minutes at 2,000 rpm using a disper blade at 10° C. to 15° C. Next, 100 g of cyan pigment (CI Pigment Blue 15:3) was added, and the mixture was stirred and mixed for 3 hours at 7,000 rpm using a disper blade at 10° C. to 15° C. The obtained dispersion was filtered through a 150 mesh filter, diluted with 110 g of ion-exchanged water, and then dispersed for 15 passes at a pressure of 150 MPa using a high-pressure homogenizer "Microfluidizer (Model: M-110K)" (manufactured by Microfluidics). The resulting dispersion was cooled under reduced pressure at 60°C to remove methyl ethyl ketone, and then some of the water was removed. The mixture was centrifuged and the liquid layer was filtered through a 10 μm pore size filter (Pall Corporation) to remove coarse particles. After mixing with ion-exchanged water, the mixture was filtered through the 10 μm pore size filter to obtain an aqueous dispersion P1 (solid content concentration 20% by mass) of pigment particles dispersed with a polymer dispersant. The volume average particle size Dv of the pigment particles contained in the resulting aqueous dispersion was 120.5 nm.

[0086] [Evaluation of storage stability of water-based ink (1)] Each water-based ink obtained in the Examples and Comparative Examples was stored in a sealed container in a thermostatic chamber at 60°C, and after 28 days, it was removed and the volume average particle size (Dv') after storage was measured by the method described above. The rate of change in the average particle size after storage at 60°C for 28 days was calculated using the following formula (rounded down to the nearest whole number), and the storage stability was evaluated according to the following evaluation criteria. Rate of change in average particle size (%) = [[Volume average particle size after storage (Dv') / Volume average particle size before storage (Dv)] - 1] x 100 (Evaluation Criteria) A: The absolute value of the rate of change in average particle size is less than 5%. B: The absolute value of the rate of change in average particle size is 5% or more and less than 15%. C: The absolute value of the average particle size change rate is 15% or more and less than 30%. D: The absolute value of the rate of change in average particle size is 30% or more and less than 50%. E: The absolute value of the rate of change in average particle diameter is 50% or more, or the water-based ink has lost fluidity and is not in a state where the volume average particle diameter Dv' can be measured.

[0087] [Evaluation of storage stability of water-based ink (2)] Each water-based ink obtained in the Examples and Comparative Examples was stored in a sealed container in a thermostatic chamber at 60°C, and after 28 days, it was removed and the pH of the water-based ink was measured by the method described above. The pH ratio of the water-based ink after storage to the pH of the water-based ink before storage (pH after storage / pH before storage) was calculated. The closer the pH ratio is to 1, the better the storage stability is.

[0088] [Evaluation of PVC adhesion of water-based ink] Each water-based ink obtained in the Examples and Comparative Examples was filled into an inkjet printer "IPSiO GX 2500" (manufactured by Ricoh Co., Ltd., piezo type), and an A4 solid image was printed on a PVC film "Transparent PVC RE-137" (manufactured by Mimaki Engineering Co., Ltd.). Then, the ink was dried for 3 minutes in a dryer at 60 ° C., and left to stand for 1 day in an environmental room at room temperature of 25 ° C. and relative humidity of 50%, to obtain a printed matter for evaluation. A cutter knife was used to make 11 vertical and horizontal cuts (1 mm interval between cuts) that reach the PVC film base on the printed surface of the printed matter for evaluation, and a grid of 100 squares was created. Next, "Cellotape (registered trademark) CT15" (manufactured by Nichiban Co., Ltd.) was attached to the grid part, and the tape was peeled off at an angle of 90 ° at a speed of 10 cm / sec, and the number of squares that did not peel off was visually confirmed. Table 3 shows the number of squares that did not peel off out of 100 squares. The more squares that did not peel off, the better the adhesion to the PVC film.

[0089] [Evaluation of Alcohol Resistance of Water-Based Ink] A print for evaluation was obtained in the same manner as in the above-mentioned evaluation of the adhesion of the water-based ink. Ethanol was diluted with ion-exchanged water to prepare ethanol aqueous solutions with different mass concentrations of ethanol for evaluation (aqueous solutions were prepared in 10 mass% increments ranging from 0 mass% to 100 mass%). Next, a cotton swab impregnated with the ethanol aqueous solution (each mass concentration) was used to lightly rub the printed surface back and forth 10 times at a speed of one back and forth per second with a width of 2 to 3 cm. The state of the rubbed printed surface was visually observed, and the highest mass concentration of ethanol at which no changes such as scratches, peeling, or cloudiness were observed on the printed surface is shown in Table 3 as an index of alcohol resistance. The higher the mass concentration of ethanol, the better the alcohol resistance.

[0090] [Table 3]

[0091] From Table 3, it can be seen that the water-based inks of Examples 2-1 to 2-8 can give printed matter having excellent storage stability, adhesion to PVC film, and alcohol resistance, as compared with the water-based inks of Comparative Examples 2-1 to 2-3. In Comparative Example 2-1, the storage stability and the alcohol resistance of the printed matter are poor because the alcohol component constituting the polyester resin is replaced by 1,5-pentanediol, which is a straight-chain aliphatic alcohol, instead of 3-methyl-1,5-pentanediol. In Comparative Example 2-2, the content of 3-methyl-1,5-pentanediol in the alcohol component constituting the polyester resin is less than 40 mol %, and therefore the adhesion to the PVC film is poor. In Comparative Example 2-3, the content of 3-methyl-1,5-pentanediol in the alcohol component constituting the polyester resin exceeds 75 mol %, and therefore the storage stability, adhesion to the PVC film, and alcohol resistance are poor. [Industrial Applicability]

[0092] According to the present invention, it is possible to provide a polyester resin aqueous dispersion which has excellent storage stability and adhesion of the coating film formed to a resin recording medium having polarity such as PVC, and which has excellent storage stability even when used in a water-based ink, and which can obtain a printed matter having excellent adhesion and abrasion resistance to solvents such as alcohol when printed on the resin printing medium, and a water-based ink containing the polyester resin aqueous dispersion, and thus can be suitably used in fields such as commercial printing and industrial printing.

Claims

1. A polyester resin aqueous dispersion containing polyester resin particles, the polyester resin particles contain a polyester resin A including a structural unit derived from an alcohol component and a structural unit derived from a carboxylic acid component, the alcohol component comprises an alkylene oxide adduct of bisphenol A and 3-methyl-1,5-pentanediol; The content of 3-methyl-1,5-pentanediol in the alcohol component is 40 mol % or more and 75 mol % or less.

2. 2. The polyester resin aqueous dispersion according to claim 1, wherein the content of the alkylene oxide adduct of bisphenol A in the alcohol component is 25 mol % or more and 60 mol % or less.

3. The polyester resin aqueous dispersion according to claim 1 or 2, wherein the acid value of the polyester resin A is from 10 mgKOH / g to 40 mgKOH / g.

4. The acid group of the polyester resin A is neutralized with a basic compound, The polyester resin aqueous dispersion according to claim 3, wherein the degree of neutralization of the polyester resin A represented by the following formula (1) is 50 mol % or more and 100 mol % or less. Degree of neutralization={[mass of basic compound added (g) / equivalent of basic compound (g / mol)] / [[acid value of polyester resin A (mg KOH / g)×mass of polyester resin A (g)] / (56×1000 (mg KOH / mol)))]}×100 (1)

5. The polyester resin aqueous dispersion according to any one of claims 1 to 4, wherein the glass transition temperature of the polyester resin A is 35°C or higher and 65°C or lower.

6. The polyester resin aqueous dispersion according to any one of claims 1 to 5, wherein the polyester resin A has a number average molecular weight of 2,500 or more and 6,000 or less.

7. 7. The polyester resin aqueous dispersion according to claim 1, wherein the carboxylic acid component constituting the polyester resin A contains 3 mol % or more and 15 mol % or less of a polyvalent carboxylic acid having three or more valences.

8. The polyester resin aqueous dispersion according to any one of claims 1 to 7, wherein the carboxylic acid component constituting the polyester resin A contains at least one selected from terephthalic acid and isophthalic acid, and the total content of the terephthalic acid and isophthalic acid in the carboxylic acid component is 60 mol% or more.

9. 9. A water-based ink comprising the polyester resin water dispersion according to claim 1 and a colorant.

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