JP7625850B2 - Binder resin composition for aqueous inkjet ink, aqueous inkjet ink and printed layer - Google Patents

Description

The present invention relates to a binder resin composition for aqueous inkjet inks, aqueous inkjet inks, and printed layers.

Inkjet (IJ) recording devices use a printing method in which small droplets of an ink composition are ejected and deposited on a recording medium such as paper. With the growing demand for on-demand printing, the use of water-based IJ printers has rapidly expanded in recent years for industrial wide-format applications.

As an inkjet ink for use in the inkjet recording device, for example, one containing a polycarbonate-based urethane resin with a breaking elongation of 300% or more has been proposed (see Patent Document 1).

JP 2017-150125 A

Inkjet inks are broadly divided into dye inks and pigment inks, with the use of pigment inks being promoted from the viewpoint of water resistance and weather resistance. However, pigment inks have low permeability into the media (printed material), and the pigment remains on the media, which means that the printed material has issues with abrasion resistance (scratch resistance). This problem can be solved by adding a water-based urethane resin to the ink as a binder to impart adhesion between the pigments, but adding a binder can reduce the storage stability and ejection properties of the ink. Recently, there has also been an increasing demand for printed materials to be washable.

The present invention has been made in consideration of the above circumstances, and aims to provide a binder resin composition that can achieve storage stability and ejection properties of the composition, as well as abrasion resistance and washability of printed matter.

As a result of extensive research, the inventors discovered that the above problems could be solved by using a specific binder resin, and thus completed the present invention.

That is, the present invention includes the following inventions.
[1] A binder resin composition for an aqueous ink-jet ink, comprising: a urethane resin (I), a basic compound (II), and an aqueous medium (III); the urethane resin (I) is a reaction product of a polyol (a), a polyisocyanate (b), and a polyamine compound (c); the polyol (a) comprises a crystalline polycarbonate diol (a1) and a diol having an acid group (a2); the polyisocyanate (b) comprises an alicyclic polyisocyanate (b1); the polyamine compound (c) comprises a linear diamine compound (c1); and the acid value of the urethane resin (I) is 15 mgKOH/g or more and 60 mgKOH/g or less.
[2] The binder resin composition for an aqueous inkjet ink according to [1], wherein the linear diamine compound (c1) contains a linear diamine compound having 5 or less carbon atoms.
[3] The binder resin composition for an aqueous ink-jet ink according to [1] or [2], wherein the basic compound (II) contains a metal hydroxide.
[4] The binder resin composition for aqueous inkjet inks according to any one of [1] to [3], wherein the crystalline polycarbonate diol (a1) contains a crystalline polycarbonate polyol having a melting point of 40° C. or higher.
[5] An aqueous inkjet ink comprising the binder resin composition for aqueous inkjet inks according to any one of [1] to [4].
[6] A printed layer formed from the aqueous inkjet ink according to any one of [1] to [5].

The binder resin composition for aqueous inkjet inks of the present invention can achieve storage stability and ejection properties of the composition, as well as scratch resistance and washability of printed matter.

The binder resin composition for aqueous inkjet inks of the present invention (hereinafter sometimes simply referred to as the "resin composition") contains a urethane resin (I), a basic compound (II) and an aqueous medium (III).

The urethane resin (I) is a reaction product of at least a polyol (a), a polyisocyanate (b), and a polyamine compound (c).

The polyol (a) contains a crystalline polycarbonate diol (a1) and a diol having an acid group (a2). By containing the crystalline polycarbonate diol (a1), the durability of the printed matter is likely to be improved, and by containing the diol having an acid group (a2), the stability of the resin composition is likely to be improved.

The crystalline polycarbonate diol (a1) is a diol having a polycarbonate skeleton and has a melting point. The melting point of the crystalline carbonate diol (a1) is preferably 40°C or higher, more preferably 50°C or higher, and even more preferably 60°C or higher, and may be, for example, 100°C or lower, 80°C or lower, or 70°C or lower.

The melting point of the crystalline polycarbonate diol (a1) can be measured by differential scanning calorimetry (DSC) as the temperature at which an endothermic peak due to melting occurs.

Specific examples of the crystalline polycarbonate diol (a1) include an esterification reaction product of a carbonate ester and a polyhydric alcohol, and a reaction product of a polyhydric alcohol and phosgene.

The carbonate ester may be one or more of different types, and examples of such carbonate esters include aliphatic carbonates, alicyclic carbonates (hereinafter, those containing an alicyclic structure may be referred to as "alicyclic"), and aromatic carbonates (hereinafter, those containing an aromatic structure may be collectively referred to as "aromatic"). Examples of the aliphatic carbonate include saturated aliphatic carbonates such as dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, di-n-butyl carbonate, diisobutyl carbonate, ethyl-n-butyl carbonate, and ethyl isobutyl carbonate; and unsaturated aliphatic carbonates such as ethylene carbonate, trimethylene carbonate, tetramethylene carbonate, 1,2-propylene carbonate, 1,2-butylene carbonate, 1,3-butylene carbonate, 2,3-butylene carbonate, 1,2-pentylene carbonate, 1,3-pentylene carbonate, 1,4-pentylene carbonate, 1,5-pentylene carbonate, 2,3-pentylene carbonate, and 2,4-pentylene carbonate. Examples of aromatic carbonates include diphenyl carbonate and dibenzyl carbonate.

As the polyhydric alcohol, one or more types can be used, and examples thereof include linear or branched diols such as ethylene glycol, propylene glycol, butanediol, pentanediol, 3-methyl-1,5-pentanediol, hexanediol, diethylene glycol, dipropylene glycol, triethylene glycol, tripropylene glycol, polyethylene glycol, and polypropylene glycol; alicyclic diols such as 1,4-cyclohexanedimethanol and hydrogenated bisphenol A; and trifunctional or higher polyols such as trimethylolmethane, trimethylolpropane, ditrimethylolpropane, pentaerythritol, and dipentaerythritol.

The content of the crystalline polycarbonate diol (a1) in the polyol (a) is preferably 25% by mass or more, more preferably 35% by mass or more, even more preferably 40% by mass or more, and is preferably 80% by mass or less, more preferably 70% by mass or less, even more preferably 60% by mass or less. By increasing the content of the crystalline polycarbonate diol (a1), the durability of the obtained coating is likely to be improved.

The diol (a2) having an acid group includes a diol having a carboxyl group or a sulfonic acid group, and preferably includes a diol having a carboxyl group. Examples of the diol having a carboxyl group include 2,2-dimethylolpropionic acid, 2,2-dimethylolbutanoic acid, 2,2-dimethylolbutyric acid, and 2,2-dimethylolvaleric acid. Among these, 2,2-dimethylolpropionic acid is preferable. In addition, polyester polyols having a carboxyl group obtained by reacting the polyol having a carboxyl group with various polycarboxylic acids can also be used. Examples of the polycarboxylic acid include aliphatic polycarboxylic acids such as succinic acid, adipic acid, sebacic acid, and dodecanedicarboxylic acid; alicyclic polycarboxylic acids such as 1,4-cyclohexanedicarboxylic acid and cyclohexanetricarboxylic acid; aromatic polycarboxylic acids such as terephthalic acid, isophthalic acid, phthalic acid, and naphthalenedicarboxylic acid; and acid anhydrides thereof.

The content of the diol having a carboxyl group in the diol having an acid group (a2) is preferably 80% by mass or more, more preferably 90% by mass or more, and even more preferably 95% by mass or more, with the upper limit being 100% by mass.

Examples of the polyol having a sulfonic acid group include polyester polyols obtained by reacting dicarboxylic acids such as 5-sulfoisophthalic acid, sulfoterephthalic acid, 4-sulfophthalic acid, and 5[4-sulfophenoxy]isophthalic acid or salts thereof with the low-molecular-weight polyols exemplified as those usable in the production of polyester polyols having an aromatic structure.

The total content of the crystalline polycarbonate diol (a1) and the diol having an acid group (a2) in the polyol (a) is preferably 30% by mass or more, more preferably 40% by mass or more, and even more preferably 50% by mass or more, with the upper limit being 100% by mass.

The polyol (a) may contain other polyols (a3) in addition to the crystalline polycarbonate diol (a1) and the diol (a2) having an acid group. Examples of the other polyols (a3) include polyether polyols, polyester polyols, polycarbonate polyols other than the crystalline polycarbonate diol (a1), low molecular weight polyols, etc.

Examples of the polyether polyol include those obtained by addition polymerization of alkylene oxide using one or more compounds having two or more active hydrogen atoms as an initiator as necessary.

Examples of the initiator include ethylene glycol, diethylene glycol, triethylene glycol, trimethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol, glycerin, trimethylolethane, trimethylolpropane, sorbitol, sucrose, aconite sugar, trimellitic acid, hemimellitic acid, phosphoric acid, ethylenediamine, diethylenetriamine, triisopropanolamine, pyrogallol, dihydroxybenzoic acid, hydroxyphthalic acid, and 1,2,3-propanetrithiol.

Examples of the alkylene oxide include ethylene oxide, propylene oxide, butylene oxide, styrene oxide, epichlorohydrin, and tetrahydrofuran.

Examples of the polyester polyol include polyester polyols obtained by reacting a low molecular weight polyol with a polycarboxylic acid; polyester polyols obtained by ring-opening polymerization of a cyclic ester compound such as ε-caprolactone; and polyester polyols obtained by copolymerizing these.

The low molecular weight polyol used in the production of the polyester polyol may be one or more, and examples of such polyols include ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, 1,2-propanediol, 1,3-propanediol, dipropylene glycol, tripropylene glycol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 1,5-pentanediol, neopentyl glycol, 1,5-hexanediol, 1,6-hexanediol, 2,5-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-deoxyglycol ... Examples of such polyols include aliphatic polyols with a molecular weight of 50 to 300, such as hexanediol, 1,11-undecanediol, 1,12-dodecanediol, 2-methyl-1,3-propanediol, neopentyl glycol, 2-butyl-2-ethyl-1,3-propanediol, 3-methyl-1,5-pentanediol, 2-ethyl-1,3-hexanediol, 2-methyl-1,8-octanediol, glycerin, trimethylolpropane, ditrimethylolpropane, trimethylolpropane, and pentaerythritol; polyols with an alicyclic structure, such as cyclohexanedimethanol and hydrogenated bisphenol A; and polyols with an aromatic structure, such as bisphenol A and bisphenol F.

The polycarboxylic acid may be one or more of these, and examples thereof include aliphatic polycarboxylic acids such as succinic acid, adipic acid, sebacic acid, and dodecanedicarboxylic acid; alicyclic polycarboxylic acids such as 1,4-cyclohexanedicarboxylic acid and cyclohexanetricarboxylic acid; aromatic polycarboxylic acids such as terephthalic acid, isophthalic acid, phthalic acid, and naphthalenedicarboxylic acid; and anhydrides or esters thereof.

The polycarbonate polyols other than the crystalline polycarbonate diol (a1) include all polycarbonate polyols that do not fall under the crystalline polycarbonate diol (a1), and examples of such compounds include those that do not fall under the crystalline polycarbonate diol (a1) among the esterification reaction products of the carbonate ester and the polyhydric alcohol, the reaction products of the polyalcohol and phosgene, etc.

The low molecular weight polyol is a polyol having a molecular weight of less than 500 (preferably 450 or less, more preferably 400 or less, with the lower limit being about 50), and examples thereof include aliphatic polyols such as ethylene glycol, diethylene glycol, 1,2-propylene glycol, dipropylene glycol, neopentyl glycol, 2-butyl-2-ethyl-1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 1,4-cyclohexanediol, 1,6-hexanediol, and cyclohexanedimethanol; cyclobutanediol Alicyclic polyols such as cyclopentanediol, 1,4-cyclohexanediol, cycloheptanediol, cyclooctanediol, butylcyclohexanediol, cyclohexanedimethanol, hydroxypropylcyclohexanol, dicyclohexanediol, hydrogenated bisphenol A, 1,3-adamantanediol, 1,1'-bicyclohexylidenediol, and cyclohexanetriol; aromatic polyols such as bisphenol A, bisphenol F, bisphenol AD, and their ethylene oxide and propylene oxide adducts.

The content of the other polyol (a3) in the polyol (a) is preferably 40% by mass or less, more preferably 30% by mass or less, and even more preferably 20% by mass or less, with the lower limit being 0% by mass.

The polyisocyanate (b) includes an alicyclic polyisocyanate (b1). The alicyclic polyisocyanate (b1) is a compound having an alicyclic structure in the molecule and having two or more isocyanate groups. The alicyclic polyisocyanate (b1) may be used alone or in combination. Examples of the alicyclic polyisocyanate (b1) include isophorone diisocyanate, bis(isocyanatomethyl)cyclohexane, dicyclohexylmethane diisocyanate, cyclohexane diisocyanate, methylcyclohexane diisocyanate, dicyclohexyldimethylmethane diisocyanate, 2,2'-dimethyldicyclohexylmethane diisocyanate, bis(4-isocyanato-n-butylidene)pentaerythritol, dimer acid diisocyanate, 2-isocyanatomethyl-3-(3-isocyanatopropyl)-5-isocyanatomethyl-bicyclo[2,2,1]-heptane, 2-isocyanatomethyl-3-(3-isocyanatopropyl)-6-isocyanatomethyl-bicyclo[2,2,1]-heptane, 2-isocyanatomethyl-2-(3-isopropyl)-5 ... cyanatopropyl)-5-isocyanatomethyl-bicyclo[2,2,1]-heptane, 2-isocyanatomethyl-2-(3-isocyanatopropyl)-6-isocyanatomethyl-bicyclo[2,2,1]-heptane, 2-isocyanatomethyl-3-(3-isocyanatopropyl)-6-(2-isocyanatoethyl)-bicyclo[2,2,1]-heptane, 2-isocyanatomethyl-3-(3-isocyanatopropyl)-6-(2-isocyanatoethyl)-bicyclo[2,2,1]-heptane, Examples of the alicyclic polyisocyanate (b1) include saturated alicyclic polyisocyanates, and preferably monocyclic (having no condensed rings) alicyclic polyisocyanates. These alicyclic polyisocyanates can be used alone or in combination of two or more.

The content of the alicyclic polyisocyanate (b1) in the polyisocyanate (b) is preferably 30% by mass or more, more preferably 40% by mass or more, even more preferably 50% by mass or more, and is preferably 95% by mass or less, more preferably 90% by mass or less, even more preferably 85% by mass or less.

The polyisocyanate (b) may contain other polyisocyanates (b2) in addition to the alicyclic polyisocyanate (b1). Examples of the other polyisocyanates (b2) include aliphatic polyisocyanates and aromatic polyisocyanates.

Examples of the aliphatic polyisocyanate include hexamethylene diisocyanate, lysine diisocyanate methyl ester, xylylene diisocyanate, and tetramethylxylylene diisocyanate. These aliphatic polyisocyanates can be used alone or in combination of two or more.

Examples of the aromatic polyisocyanate include phenylene diisocyanate, tolylene diisocyanate, diphenylmethane diisocyanate, and naphthalene diisocyanate. These aromatic polyisocyanates can be used alone or in combination of two or more.

The molar ratio (NCO/OH) of the isocyanate groups contained in the polyisocyanate (b) to the hydroxyl groups contained in the polyol (b1) is preferably 1.05 or more, and preferably 3 or less, more preferably 2 or less.

The polyamine compound (c) is a compound having two or more amino groups in one molecule, and includes a linear diamine compound (c1). By including the linear diamine compound (c1), the durability of the printed matter can be improved.

The linear diamine compound (c1) is a compound having two amino groups in one molecule and no side chains. Examples of the linear diamine compound (c1) include ethylenediamine, 1,3-propanediamine, 1,3-butanediamine, 1,4-butanediamine, 1,5-pentamethylenediamine, and 1,6-hexamethylenediamine.

The number of carbon atoms in the linear diamine compound (c1) is preferably 6 or less, more preferably 5 or less, even more preferably 4 or less, and preferably 2 or more.

The content of the linear diamine compound (c1) in the polyamine compound (c) is preferably 80% by mass or more, more preferably 90% by mass or more, and even more preferably 95% by mass or more, with the upper limit being 100% by mass.

The polyamine compound (c) may contain a polyamine compound (c2) other than the linear diamine compound (c1). Examples of the other polyamine compound (c2) include alicyclic diamine compounds such as 1,4-cyclohexanediamine, 3-aminomethyl-3,5,5-trimethylcyclohexylamine (isophoronediamine), 4,4'-dicyclohexylmethanediamine, 2,5-bis(aminomethyl)bicyclo[2.2.1]heptane, 2,6-bis(aminomethyl)bicyclo[2.2.1]heptane, and 1,3-bis(aminomethyl)cyclohexane; hydrazine compounds such as hydrazine; aromatic diamine compounds such as o-tolylenediamine, m-tolylenediamine, and p-tolylenediamine; triamine compounds such as diethylenetriamine, and polyamine compounds having four or more amino groups such as triethylenetetramine and tetraethylenepentamine.

The amount of the polyamine compound (c) is preferably 0.5 parts by mass or more, more preferably 1.0 parts by mass or more, and even more preferably 2.0 parts by mass or more, relative to 100 parts by mass of the total of the polyol (a) and the polyisocyanate (b), and is preferably 10.0 parts by mass or less, more preferably 7.5 parts by mass or less, and even more preferably 5.0 parts by mass or less.

The order of reaction of the polyol (a), polyisocyanate (b) and polyamine compound (c) is not particularly limited, and the polyol (a), polyisocyanate (b) and polyamine compound (c) may be reacted at once or sequentially. For example, it is preferable to react the reaction product of the polyol (a) and polyisocyanate (b) with the polyamine compound (c).

The acid value of the urethane resin (I) is 15 mgKOH/g or more, preferably 20 mgKOH/g or more, more preferably 25 mgKOH/g or more, even more preferably 30 mgKOH/g or more, and is 60 mgKOH/g or less, preferably 55 mgKOH/g or less, more preferably 50 mgKOH/g or less, and more preferably 40 mgKOH/g or less.

The weight average molecular weight of the urethane resin (I) is preferably 10,000 or more, more preferably 20,000 or more, more preferably 50,000 or more, and is preferably 2,000,000 or less, more preferably 1,000,000 or less, and even more preferably 500,000 or less.

In the present invention, the weight average molecular weight and number average molecular weight can be measured using gel permeation chromatography and converted into values using polystyrene as a standard sample.

The content of the urethane resin (I) in the resin composition 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 40% by mass or less, even more preferably 35% by mass or less.

By including the basic compound (II), the acid groups contained in the urethane resin (I) can be neutralized, improving the stability of the resin composition. Examples of the basic compound include organic amines with a boiling point of 200°C or higher, such as ammonia, triethylamine, morpholine, monoethanolamine, and diethylethanolamine; and metal hydroxides, such as sodium hydroxide, potassium hydroxide, and lithium hydroxide.

In particular, the basic compound (II) preferably contains a metal hydroxide. The metal hydroxide is preferably an alkali metal hydroxide or an alkaline earth metal hydroxide, and more preferably an alkali metal hydroxide.

The content of the metal hydroxide (preferably an alkali metal hydroxide and/or an alkaline earth metal hydroxide, more preferably an alkali metal hydroxide) in the basic compound (II) is preferably 50% by mass or more, more preferably 60% by mass or more, and even more preferably 80% by mass or more, with the upper limit being 100% by mass.

From the viewpoint of improving the aqueous dispersion stability of the resin composition, the basic compound (II) has a molar ratio (basic group/acid group) of the product of the basic group and its valence in the basic compound to the product of the acid group and its valence in the urethane resin is preferably 0.5 or more, more preferably 0.8 or more, and is preferably 3 or less, more preferably 2 or less.

The aqueous medium (III) may be water, an organic solvent miscible with water, or a mixture thereof. Examples of the organic solvent miscible with water include alcohol solvents such as methanol, ethanol, n-propanol, isopropyl alcohol, 1,2-propylene glycol, and 1,3-butylene glycol; ketone solvents such as acetone and methyl ethyl ketone; glycol ether solvents such as ethylene glycol-n-butyl ether, diethylene glycol-n-butyl ether, diethylene glycol monoethyl ether acetate, diethylene glycol dimethyl ether, propylene glycol methyl ether, dipropylene glycol methyl ether, dipropylene glycol dimethyl ether, dipropylene glycol-n-butyl ether, and tripropylene glycol methyl ether; lactam solvents such as N-methyl-2-pyrrolidone and N-ethyl-2-pyrrolidone; and amide solvents such as N,N-dimethylformamide. These water-miscible organic solvents may be used alone or in combination of two or more.

From the viewpoints of safety and reducing the burden on the environment, the aqueous medium (III) is preferably water alone or a mixture of water and an organic solvent miscible with water, and more preferably water alone.

The content of the aqueous medium (III) in the total amount of the resin composition is preferably 30% by mass or more, more preferably 50% by mass or more, and is preferably 80% by mass or less, more preferably 70% by mass or less.

The resin composition may contain other additives (IV) in addition to the urethane resin (I), the basic compound (II) and the aqueous medium (III). Examples of the other additives (IV) include crosslinkers, plasticizers, antistatic agents, waxes, surfactants, light stabilizers, flow regulators, dyes, leveling agents, rheology control agents, UV absorbers, antioxidants, photocatalytic compounds, preservatives, viscosity regulators, pH regulators, chelating agents, etc.

The content of the other additives in the non-volatile content of the resin composition is, for example, 30% by mass or less, for example, 20% by mass or less, and the lower limit is 0% by mass, and may be 0.1% by mass or more.

An inkjet ink composition containing the resin composition and a printed layer formed from the inkjet ink composition are also included within the technical scope of the present invention.

The inkjet ink composition contains the urethane resin (I), the basic compound (II), the aqueous medium (III) and a colorant, and may further contain additives such as an organic solvent, a surface conditioner, a pigment dispersion resin, a drying inhibitor, a penetrating agent, and a surfactant.

The colorant may be a dye or a pigment, and preferably contains a pigment.

As the pigment, for example, a compound classified as a pigment in the Color Index (published by The Society of Dyers and Colourists) can be used, and examples of the pigment include inorganic pigments and organic pigments.

Examples of the inorganic pigments include iron oxide; carbon black (carbon black produced by the contact method, furnace method, thermal method, etc.); titanium oxide, etc.

Examples of the carbon black include #2300, #2200B, #990, #900, #960, #980, #33, #40, #45, #45L, #52, HCF88, MA7, MA8, MA100, etc. (all manufactured by Mitsubishi Chemical Corporation); Raven series (5750, 5250, 5000, 3500, 1255, 700, etc.) (all manufactured by Columbia Chemical); Regal series (400R, 330R, 660R, etc.), Mogul series (L, 700, etc.), Monarch series (800, 880, 900, 1000, 100, 1300, 1400, etc.) (all manufactured by Cabot Corporation); Color Black series (FW1, FW2, FW2V, FW18, FW200, S150, S160, S170), Printex series (35, U, V, 1400U, etc.), Special Black series (6, 5, 4, 4A, etc.), NIPEX series (150, 160, 170, 180, 95, 90, 85, 80, 75, etc.) (all manufactured by Orion Engineered Carbons Co., Ltd.), etc.

The organic pigments may be of one or more types, and according to their chemical structure, examples include azo pigments such as azo lake pigments, insoluble azo pigments, condensed azo pigments, and chelate azo pigments; polycyclic pigments such as phthalocyanine pigments, perylene pigments, perinone pigments, anthraquinone pigments, quinacridone pigments, dioxazine pigments, thioindigo pigments, isoindoline pigments, and quinophthalone pigments; dye chelates such as basic dye chelates and acid dye chelates; nitro pigments; nitroso pigments; and aniline black.

Specific examples of the organic pigment include:
Yellow pigments such as C.I. Pigment Yellow 1, 2, 12, 13, 14, 16, 17, 73, 74, 75, 83, 93, 95, 97, 98, 109, 110, 114, 120, 128, 129, 138, 150, 151, 154, 155, 174, 180, 185;
Magenta pigments such as C.I. Pigment Red 5, 7, 12, 48(Ca), 48(Mn), 57(Ca), 57:1, 112, 122, 123, 146, 150, 168, 176, 184, 185, 202, 209, 213, 269, 282;
Cyan pigments such as C.I. Pigment Blue 1, 2, 3, 15, 15:1, 15:2, 15:3, 15:4, 15:6, 16, 22, 60, 63, 66;
Orange pigments such as C.I. Pigment Orange 5, 13, 16, 17, 34, 36, 43, 51, 64, 71;
Violet pigments such as C.I. Pigment Violet 1, 3, 5:1, 16, 19, 23, 38;
Green pigments such as C.I. Pigment Green 1, 4, 7, 8, 10, 17, 18, 36;
C.I. Pigment Red 1, 2, 3, 5, 17, 22, 23, 31, 38, 48:2, 48:3, 48:4, 49:1, 52:2, 53:1, 57:1, 60:1, 63:1, 63:2, 64:1, 81, 83, 88, 101, 104, 105, 106, 108, 112, 114, 122, 123, 146, 149, 150, 166, 168, 170, 172, 177, 178, 179, 184, 185, 190, 193, 202, 207, 208, 209, 213, 219, 224, 254, 264 and other red pigments.

The primary particle diameter of the pigment is preferably 25 μm or less, more preferably 10 μm or less, and even more preferably 1 μm or less, from the viewpoint of dispersibility, and may be, for example, 10 nm or more, 30 nm or more, from the viewpoint of stability. The primary particle diameter can be measured by a transmission electron microscope (TEM).

From the viewpoint of dispersibility, the volume average particle diameter of the pigment is preferably 1 μm or less, more preferably 250 nm or less, and even more preferably 200 nm or less, and from the viewpoint of stability, it may be, for example, 10 nm or more, 50 nm or more. The volume average particle diameter of the pigment can be measured by a laser diffraction method.

The content of the pigment in the colorant is preferably 80% by mass or more, more preferably 90% by mass or more, and even more preferably 95% by mass or more, with the upper limit being 100% by mass.

The content of the colorant in the solid content of the inkjet ink composition is preferably 1% by mass or more, more preferably 5% by mass or more, and even more preferably 10% by mass or more, and is preferably 90% by mass or less, more preferably 80% by mass or less, and even more preferably 70% by mass or less.

The pigment dispersant is a compound having a hydrophilic portion and a hydrophobic portion, and has the effect of improving the dispersibility of the pigment in the aqueous medium (III). Examples of the pigment dispersant include styrene-acrylic acid copolymers such as styrene-(meth)acrylic acid copolymer, styrene-(meth)acrylic acid ester-(meth)acrylic acid copolymer, and (meth)acrylic acid ester-(meth)acrylic acid copolymer. When the styrene-acrylic acid copolymer is used, a basic compound such as potassium hydroxide may be coexisted in the aqueous pigment dispersion.

The content of the pigment dispersant is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, and even more preferably 20 parts by mass or more, relative to 100 parts by mass of the colorant, and is preferably 100 parts by mass or less, more preferably 70 parts by mass or less, and even more preferably 50 parts by mass or less.

As the organic solvent, hydrophilic organic solvents (organic solvents that are miscible with water at 25°C) are preferred, specifically, ketone solvents such as acetone, methyl ethyl ketone, methyl butyl ketone, and methyl isobutyl ketone; alcohol solvents such as methanol, ethanol, 1-propanol, 2-propanol, 2-methyl-1-propanol, 1-butanol, 2-butanol, pentyl alcohol, and 2-methoxyethanol; ether solvents such as tetrahydrofuran, 1,4-dioxane, and 1,2-dimethoxyethane; amide solvents such as dimethylformamide and N-methylpyrrolidone; glycol solvents such as ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, propylene glycol, dipropylene glycol, polyethylene glycol, and polypropylene glycol; butanediol, pentanediol, and the like. diol solvents such as diol, hexanediol, and diols of the same group; glycol ester solvents such as propylene glycol laurate; glycol ether solvents such as diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, diethylene glycol monohexyl ether, propylene glycol monoethyl ether, propylene glycol monomethyl ether, dipropylene glycol monoethyl ether, and triethylene glycol monoethyl ether; sulfolane; lactone solvents such as γ-butyrolactone; lactam solvents such as N-methylpyrrolidone, N-(2-hydroxyethyl)pyrrolidone, and 2-pyrrolidone; nitrile solvents such as acetonitrile; glycerin; glycerin derivatives such as glycerin to which polyoxyalkylene has been added; and mixed solvents of one or more of these.

When a cyan pigment is used as the pigment, the organic solvent is preferably a glycol solvent; a lactam solvent; an ether solvent; a diol solvent; a mixed solvent of a lactam solvent and an alcohol solvent; a mixed solvent of a lactam solvent and a glycol solvent, and more preferably triethylene glycol; N-(2-hydroxyethyl)pyrrolidone; dipropylene glycol; N-methylpyrrolidone; 2-pyrrolidone; tetrahydrofuran; 1,2-hexanediol; a mixed solvent of N-methylpyrrolidone and methanol; a mixed solvent of 2-pyrrolidone and dipropylene glycol. In the mixed solvent, the volume ratio (lactam solvent/alcohol solvent, lactam solvent/glycol solvent) is preferably 1/9 to 9/1, more preferably 3/7 to 7/3, and even more preferably 4/6 to 6/4.

When a magenta pigment is used as the pigment, the organic solvent is preferably a glycol solvent; a lactam solvent; a mixed solvent of an ether solvent and an alcohol solvent; a mixed solvent of a lactam solvent and an alcohol solvent, and more preferably dipropylene glycol; triethylene glycol; N-(2-hydroxyethyl)pyrrolidone; N-methylpyrrolidone; a mixed solvent of tetrahydrofuran and methanol; a mixed solvent of 2-pyrrolidone and dipropylene glycol, and the like. In the mixed solvent, the volume ratio (ether solvent/alcohol solvent, lactam solvent/alcohol solvent) is preferably 1/9 to 9/1, more preferably 3/7 to 7/3, and even more preferably 4/6 to 6/4.

When a yellow pigment is used as the pigment, the organic solvent is preferably a ketone solvent, a nitrile solvent, a glycol solvent, a lactam solvent, or a mixed solvent of a lactam solvent and a glycol solvent, and more preferably a methyl ethyl ketone, an acetonitrile, a propylene glycol, a triethylene glycol, an N-(2-hydroxyethyl)pyrrolidone, an N-methylpyrrolidone, or a mixed solvent of 2-pyrrolidone and dipropylene glycol. In the mixed solvent, the volume ratio (lactam solvent/glycol solvent) is preferably 1/9 to 9/1, more preferably 3/7 to 7/3, and even more preferably 4/6 to 6/4.

When a black pigment is used as the pigment, the organic solvent is preferably a lactam solvent, a ketone solvent, or an amide solvent, and more preferably triethylene glycol, N-(2-hydroxyethyl)pyrrolidone, 2-pyrrolidone, N-methylpyrrolidone, or methyl ethyl ketone.

When an orange pigment is used as the pigment, the organic solvent is preferably an ether solvent; a lactam solvent; a mixed solvent of a lactam solvent and a glycol solvent, and more preferably triethylene glycol; N-(2-hydroxyethyl)pyrrolidone; tetrahydrofuran; 2-pyrrolidone; a mixed solvent of 2-pyrrolidone and dipropylene glycol; a mixed solvent of N-methylpyrrolidone and dipropylene glycol, and even more preferably triethylene glycol; N-(2-hydroxyethyl)pyrrolidone. In the mixed solvent, the volume ratio (lactam solvent/glycol solvent) is preferably 1/9 to 9/1, more preferably 3/7 to 7/3, and even more preferably 4/6 to 6/4.

When a violet pigment is used as the pigment, the organic solvent is preferably a lactam solvent; an alcohol solvent; a mixed solvent of a lactam solvent and a glycol solvent, and more preferably triethylene glycol; N-(2-hydroxyethyl)pyrrolidone; N-methylpyrrolidone; 2-pyrrolidone; 2-propanol; or a mixed solvent of 2-pyrrolidone and dipropylene glycol. In the mixed solvent, the volume ratio (lactam solvent/glycol solvent) is preferably 1/9 to 9/1, more preferably 3/7 to 7/3, and even more preferably 4/6 to 6/4.

When a green pigment is used as the pigment, the organic solvent is preferably a glycol solvent, a lactam solvent, an alcohol solvent, a diol solvent, or a mixed solvent of a lactam solvent and a glycol solvent, and more preferably dipropylene glycol, triethylene glycol, N-(2-hydroxyethyl)pyrrolidone, N-methylpyrrolidone, 2-propanol, 1,2-hexanediol, or a mixed solvent of 2-pyrrolidone and dipropylene glycol. In the mixed solvent, the volume ratio (lactam solvent/glycol solvent) is preferably 1/9 to 9/1, more preferably 3/7 to 7/3, and even more preferably 4/6 to 6/4.

When a red pigment is used as the pigment, the organic solvent is preferably a glycol solvent; an alcohol solvent; a diol solvent; a mixed solvent of a lactam solvent and a glycol solvent, and more preferably triethylene glycol; N-(2-hydroxyethyl)pyrrolidone; dipropylene glycol; 2-propanol: 1,2-hexanediol; a mixed solvent of 2-pyrrolidone and dipropylene glycol. In the mixed solvent, the volume ratio (lactam solvent/glycol solvent) is preferably 1/9 to 9/1, more preferably 3/7 to 7/3, and even more preferably 4/6 to 6/4.

From the viewpoint of dispersibility and storage stability, the organic solvent is preferably 1 to 300 parts by mass, more preferably 4 to 200 parts by mass, per 100 parts by mass of the pigment.

The inkjet ink composition can be produced by first preparing a colorant dispersion by mixing and dispersing the colorant, the pigment dispersant, the organic solvent, the aqueous medium, and a basic compound used as necessary, and then mixing the resin composition, a drying inhibitor, a penetrant, a surfactant, and other additives. When preparing the colorant dispersion, examples of the mixing and dispersion method include a wet dispersion method and a kneading dispersion method, and the wet dispersion method is preferred.

As the drying inhibitor, it is preferable to use one that is miscible with the aqueous medium and has an effect of preventing clogging of the inkjet printer head, such as glycerin, ethylene glycol, diethylene glycol, triethylene glycol, triethylene glycol mono-n-butyl ether, polyethylene glycol with a molecular weight of 2000 or less, propylene glycol, dipropylene glycol, tripropylene glycol, 1,3-propylene glycol, isopropylene glycol, isobutylene glycol, 1,4-butanediol, 1,3-butanediol, 1,5-pentanediol, 1,6-hexanediol, mesoerythritol, pentaerythritol, etc. Among them, it is preferable to use glycerin and triethylene glycol as the drying inhibitor, since they are highly safe and can impart excellent effects on the drying property and ejection performance of the ink. The content of the drying inhibitor in the inkjet ink composition is preferably 3 to 50% by mass.

Examples of the penetrant include lower alcohols such as ethanol and isopropyl alcohol; and glycol monoethers of alkyl alcohols such as ethylene glycol hexyl ether, diethylene glycol butyl ether, and propylene glycol propyl ether. The content of the penetrant in the inkjet ink composition is preferably 0.01 to 10% by mass from the viewpoints of improving the permeability of the ink into the recording medium and adjusting the ink dot diameter on the recording medium.

Examples of the surfactant include anionic surfactants, nonionic surfactants, cationic surfactants, amphoteric surfactants, etc., and from the viewpoint of adjusting the ink properties such as surface tension, anionic surfactants and nonionic surfactants are preferred.

Examples of anionic surfactants include alkylbenzenesulfonates, alkylphenylsulfonates, alkylnaphthalenesulfonates, higher fatty acid salts, sulfate ester salts of higher fatty acid esters, sulfonates of higher fatty acid esters, sulfate ester salts and sulfonates of higher alcohol ethers, higher alkyl sulfosuccinates, polyoxyethylene alkyl ether carboxylates, polyoxyethylene alkyl ether sulfates, alkyl phosphates, polyoxyethylene alkyl ether phosphates, etc., and specific examples thereof include dodecylbenzenesulfonates, isopropylnaphthalenesulfonates, monobutylphenylphenol monosulfonates, monobutylbiphenylsulfonates, dibutylphenylphenol disulfonates, etc.

Examples of nonionic surfactants include polyoxyethylene alkyl ethers, polyoxyethylene alkylphenyl ethers, polyoxyethylene fatty acid esters, sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters, polyoxyethylene sorbitol fatty acid esters, glycerin fatty acid esters, polyoxyethylene glycerin fatty acid esters, polyglycerin fatty acid esters, sucrose fatty acid esters, polyoxyethylene alkylamines, polyoxyethylene fatty acid amides, fatty acid alkylol amides, alkyl alkanol amides, acetylene glycol, oxyethylene adducts of acetylene glycol, polyethylene glycol polypropylene glycol block copolymers, and the like. Among these, polyoxyethylene nonylphenyl ether, polyoxyethylene octylphenyl ether, polyoxyethylene dodecylphenyl ether, polyoxyethylene alkyl ethers, polyoxyethylene fatty acid esters, sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters, fatty acid alkylol amides, acetylene glycol, oxyethylene adducts of acetylene glycol, and polyethylene glycol polypropylene glycol block copolymers are preferred.

Other surfactants that may be used include silicone surfactants such as polysiloxane oxyethylene adducts; fluorine-based surfactants such as perfluoroalkyl carboxylates, perfluoroalkyl sulfonates, and oxyethylene perfluoroalkyl ethers; and biosurfactants such as spiculisporic acid, rhamnolipids, and lysolecithin.

From the viewpoint of effectively preventing bleeding of printed images, etc., the content of the surfactant in the inkjet ink composition is preferably 0.001 to 2% by mass, more preferably 0.001 to 1.5% by mass, and even more preferably 0.01 to 1% by mass.

The water-based ink for inkjet recording can be used for printing on various recording media. The recording media can be absorbent recording media such as copy paper (PPC paper) commonly used in copiers, recording media having an ink absorbing layer, non-absorbent recording media that do not absorb ink, and poorly absorbent recording media that have low ink absorbency.

The binder resin composition for aqueous inkjet inks of the present invention is useful for printing on various recording media because it can achieve storage stability and ejection properties of the composition, as well as scratch resistance and washability of printed matter.

The present invention will be explained in more detail below with reference to examples. However, the present invention is not limited to the following examples, and it is of course possible to carry out the invention with appropriate modifications within the scope of the above and below-mentioned aims, and all such modifications are included in the technical scope of the present invention.

(Production Example 1: Synthesis of Water-Based Urethane Resin Dispersion 1)
In a four-neck flask equipped with a thermometer, a stirrer, a reflux condenser and a nitrogen inlet tube, 500.0 parts by mass of ETERNACOLL UH-100 (Ube Industries, crystalline polycarbonate diol with a number average molecular weight of 1000) as a polymer diol, 33.4 parts by mass of 2,2-dimethylolpropionic acid (DMPA) as an acidic diol, and 207.6 parts by mass of methyl ethyl ketone (MEK) as a solvent were added and thoroughly stirred. Next, 295.1 parts by mass of hydrogenated 4,4'-diphenylmethane diisocyanate (H12MDI) as an isocyanate and 0.16 parts by mass of dibutyltin dilaurate as a catalyst were added and reacted at 75 ° C. for 4 hours. After the reaction, 346.9 parts by mass of MEK were added, stirred for 30 minutes and cooled to 40 ° C. or less to obtain a urethane prepolymer solution.
The obtained urethane prepolymer solution was added with a 20% by mass potassium hydroxide aqueous solution (corresponding to 13.3 parts by mass of solid content), and the acid group was neutralized by stirring for 15 minutes. Then, 2540.6 parts by mass of ion-exchanged water was gradually added under strong stirring to emulsify the urethane, and then 20.3 parts by mass of ethylenediamine (EDA) was added as a chain extender, and the mixture was stirred at 40°C for 3 hours to carry out a chain extension reaction. After the reaction was completed, MEK was distilled off by reduced pressure distillation to synthesize an aqueous urethane resin dispersion 1 with a non-volatile content of 30% by mass and an acid value of 15 mgKOH/g of solid content.

(Production Example 2: Synthesis of Water-Based Urethane Resin Dispersion 2)
An aqueous urethane resin dispersion 2 having a nonvolatile content of 30 mass% and a solid acid value of 30 mgKOH/g was synthesized in the same manner as in Production Example 1, except that the amounts of UH-100 were changed from 500.0 parts by mass to 400.0 parts by mass, DMPA from 33.4 parts by mass to 59.0 parts by mass, H12MDI from 330.2 parts by mass to 330.5 parts by mass, potassium hydroxide from 12.0 parts by mass to 23.5 parts by mass, and EDA from 20.3 parts by mass to 22.7 parts by mass.

(Production Example 3: Synthesis of Water-Based Urethane Resin Dispersion 3)
An aqueous urethane resin dispersion 3 having a nonvolatile content of 30 mass% and a solid acid value of 45 mgKOH/g was synthesized in the same manner as in Production Example 1, except that the amounts of UH-100 were changed from 500.0 parts by mass to 300.0 parts by mass, DMPA from 33.4 parts by mass to 80.5 parts by mass, H12MDI from 330.2 parts by mass to 354.2 parts by mass, potassium hydroxide from 12.0 parts by mass to 32.0 parts by mass, and EDA from 20.3 parts by mass to 24.3 parts by mass.

(Production Example 4: Synthesis of Water-Based Urethane Resin Dispersion 4)
An aqueous urethane resin dispersion 4 having a nonvolatile content of 30% by mass and a solid acid value of 60 mgKOH/g was synthesized in the same manner as in Production Example 1, except that the amounts of UH-100 were changed from 500.0 parts by mass to 250.0 parts by mass, DMPA from 33.4 parts by mass to 117.3 parts by mass, H12MDI from 330.2 parts by mass to 442.7 parts by mass, potassium hydroxide from 12.0 parts by mass to 46.6 parts by mass, and EDA from 20.3 parts by mass to 30.4 parts by mass.

(Production Example 5: Synthesis of Aqueous Urethane Resin Dispersion 5)
An aqueous urethane resin dispersion 5 having a nonvolatile content of 30% by mass and a solid acid value of 40 mgKOH/g was synthesized in the same manner as in Production Example 1, except that the amounts of UH-100 were changed from 500.0 parts by mass to 350.0 parts by mass, DMPA from 33.4 parts by mass to 75.1 parts by mass, H12MDI from 330.2 parts by mass to 358.1 parts by mass, potassium hydroxide from 12.0 parts by mass to 29.9 parts by mass, and EDA from 20.3 parts by mass to 41.8 parts by mass of 1,5-pentanediamine were changed.

(Production Example 6: Synthesis of Water-Based Urethane Resin Dispersion 6)
An aqueous urethane resin dispersion 6 having a nonvolatile content of 30 mass% and an acid value of solids of 20 mgKOH/g was synthesized in the same manner as in Production Example 1, except that 33.4 parts by mass of DMPA was changed to 40.2 parts by mass, 330.2 parts by mass of H12MDI was changed to 266.8 parts by mass of isophorone diisocyanate (IPDI), 12.0 parts by mass of potassium hydroxide was changed to 16.0 parts by mass, and 20.3 parts by mass of EDA was changed to 21.6 parts by mass.

(Production Example 7: Synthesis of Water-Based Urethane Resin 7 Dispersion)
An aqueous urethane resin dispersion 7 having a nonvolatile content of 30% by mass and a solid acid value of 40 mgKOH/g was synthesized in the same manner as in Production Example 1, except that the amount of UH-100 was changed from 500.0 parts by mass to 350.0 parts by mass, the amount of DMPA was changed from 33.4 parts by mass to 70.4 parts by mass, the amount of H12MDI was changed from 330.2 parts by mass to 291.8 parts by mass of isophorone diisocyanate (IPDI), the amount of potassium hydroxide was changed from 12.0 parts by mass to 28.0 parts by mass, and the amount of EDA was changed from 20.3 parts by mass to 23.7 parts by mass.

(Production Example 8: Synthesis of aqueous urethane resin dispersion 8)
An aqueous urethane resin dispersion 8 having a nonvolatile content of 30% by mass and a solid acid value of 40 mgKOH/g was synthesized in the same manner as in Production Example 1, except that 500.0 parts by mass of UH-100 was changed to 400.0 parts by mass of ETERNACOLL UH-200 (manufactured by Ube Industries, a crystalline polycarbonate diol having a number average molecular weight of 2000), 33.4 parts by mass of DMPA was changed to 75.1 parts by mass, 330.2 parts by mass of H12MDI was changed to 299.1 parts by mass, and 12.0 parts by mass of potassium hydroxide was changed to 29.9 parts by mass.

(Production Example 9: Synthesis of Aqueous Urethane Resin Dispersion 9)
An aqueous urethane resin dispersion 9 having a nonvolatile content of 30% by mass and a solid acid value of 40 mgKOH/g was synthesized in the same manner as in Production Example 1, except that 500.0 parts by mass of UH-100 was changed to 450.0 parts by mass of ETERNACOLL UH-300 (manufactured by Ube Industries, a crystalline polycarbonate diol having a number average molecular weight of 3000), 33.4 parts by mass of DMPA was changed to 76.4 parts by mass, 330.2 parts by mass of H12MDI was changed to 283.3 parts by mass, 12.0 parts by mass of potassium hydroxide was changed to 30.4 parts by mass, and 20.3 parts by mass of EDA was changed to 19.5 parts by mass.

(Production Example 10: Synthesis of Water-Based Urethane Resin Dispersion 10)
An aqueous urethane resin dispersion 10 having a nonvolatile content of 30% by mass and a solid acid value of 40 mgKOH/g was synthesized in the same manner as in Production Example 1, except that the amount of UH-100 was changed from 500.0 parts by mass to 350.0 parts by mass, DMPA was changed from 33.4 parts by mass to 75.1 parts by mass, H12MDI was changed from 330.2 parts by mass to 358.1 parts by mass, potassium hydroxide was changed from 12.0 parts by mass to 29.9 parts by mass, and EDA was changed from 20.3 parts by mass to 47.6 parts by mass of 1,6-hexamethylenediamine (HDA).

(Production Example 11: Synthesis of Water-Based Urethane Resin Dispersion 11)
In Production Example 1, an aqueous urethane resin dispersion 11 having a nonvolatile content of 30% by mass and a solid acid value of 40 mgKOH/g was synthesized in the same manner except that the amounts of UH-100, DMPA, and H12MDI were changed from 33.4 parts by mass to 75.1 parts by mass, from 330.2 parts by mass to 358.1 parts by mass, potassium hydroxide, and EDA were changed from 20.3 parts by mass to 2,2-dimethyl-1,3-propanediamine (DMPDA), were changed to 41.8 parts by mass.

(Production Example 12: Synthesis of Water-Based Urethane Resin Dispersion 12)
An aqueous urethane resin dispersion 12 having a nonvolatile content of 30% by mass and a solid acid value of 40 mgKOH/g was synthesized in the same manner as in Production Example 1, except that the amount of UH-100 was changed from 500.0 parts by mass to 450.0 parts by mass, DMPA was changed from 33.4 parts by mass to 75.4 parts by mass, H12MDI was changed from 330.2 parts by mass to 255.5 parts by mass of hexamethylene diisocyanate (HDI), potassium hydroxide was changed from 12.0 parts by mass to 30.0 parts by mass, and EDA was changed from 20.3 parts by mass to 27.4 parts by mass.

(Production Example 13: Synthesis of Water-Based Urethane Resin Dispersion 13)
In Production Example 1, an aqueous urethane resin dispersion 13 having a nonvolatile content of 30% by mass and a solid acid value of 40 mgKOH/g was synthesized in the same manner except that 500.0 parts by mass of UH-100 was replaced with 280.0 parts by mass of ETERNACOLL UH-50 (manufactured by Ube Industries, a crystalline polycarbonate diol having a number average molecular weight of 500), 33.4 parts by mass of DMPA was replaced with 75.1 parts by mass, 330.2 parts by mass of H12MDI was replaced with 440.7 parts by mass, 12.0 parts by mass of potassium hydroxide was replaced with 29.9 parts by mass, and 20.3 parts by mass of EDA was replaced with 30.3 parts by mass.

(Production Example 14: Synthesis of Aqueous Urethane Resin Dispersion 14)
In Production Example 1, an aqueous urethane resin dispersion 14 having a nonvolatile content of 30% by mass and a solid acid value of 40 mgKOH/g was synthesized in the same manner except that 500.0 parts by mass of UH-100 was changed to 350.0 parts by mass of DURANOL T5651 (amorphous polycarbonate diol having a molecular weight of 1000, manufactured by Asahi Kasei), 33.4 parts by mass of DMPA was changed to 75.1 parts by mass, 330.2 parts by mass of H12MDI was changed to 358.1 parts by mass, 12.0 parts by mass of potassium hydroxide was changed to 29.9 parts by mass, and 20.3 parts by mass of EDA was changed to 24.6 parts by mass.

(Production Example 15: Synthesis of Aqueous Urethane Resin Dispersion 15)
An aqueous urethane resin dispersion 15 having a nonvolatile content of 30% by mass and a solid acid value of 40 mgKOH/g was synthesized in the same manner as in Production Example 1, except that the 500.0 parts by mass of UH-100 was changed to 350.0 parts by mass of EXCENOL 1020 (polyether diol having a molecular weight of 1000, manufactured by AGC, hereinafter referred to as PPG1000), the 33.4 parts by mass of DMPA was changed to 75.1 parts by mass, the 330.2 parts by mass of H12MDI was changed to 358.1 parts by mass, the 12.0 parts by mass of potassium hydroxide was changed to 29.9 parts by mass, and the 20.3 parts by mass of EDA was changed to 24.6 parts by mass.

(Production Example 16: Synthesis of Aqueous Urethane Resin Dispersion 16)
An aqueous urethane resin dispersion 16 having a nonvolatile content of 30% by mass and a solid acid value of 40 mgKOH/g was synthesized in the same manner as in Production Example 1, except that the 500.0 parts by mass of UH-100 was changed to 350.0 parts by mass of Polylite OD-X-2155 (polyester diol having a molecular weight of 1000, manufactured by DIC, hereinafter referred to as PEs), the 33.4 parts by mass of DMPA was changed to 75.1 parts by mass, the 330.2 parts by mass of H12MDI was changed to 358.1 parts by mass, the 12.0 parts by mass of potassium hydroxide was changed to 29.9 parts by mass, and the 20.3 parts by mass of EDA was changed to 24.6 parts by mass.

(Production Example 17: Synthesis of Water-Based Urethane Resin Dispersion 17)
An aqueous urethane resin dispersion 17 having a nonvolatile content of 30 mass% and a solid acid value of 10 mgKOH/g was synthesized in the same manner as in Production Example 1, except that the amounts of DMPA, H12MDI, and EDA were changed from 33.4 parts by mass to 20.1 parts by mass, from 330.2 parts by mass to 255.8 parts by mass, from 12.0 parts by mass to 8.0 parts by mass, and EDA were changed from 20.3 parts by mass to 17.6 parts by mass.

(Production Example 18: Synthesis of Aqueous Urethane Resin Dispersion 18)
An aqueous urethane resin dispersion 18 having a nonvolatile content of 30% by mass and a solid acid value of 70 mgKOH/g was synthesized in the same manner as in Production Example 1, except that the amounts of UH-100 were changed from 500.0 parts by mass to 200.0 parts by mass, DMPA from 33.4 parts by mass to 134.1 parts by mass, H12MDI from 330.2 parts by mass to 472.2 parts by mass, potassium hydroxide from 12.0 parts by mass to 53.3 parts by mass, and EDA from 20.3 parts by mass to 32.5 parts by mass.

(Production Example 19: Synthesis of Aqueous Urethane Resin Dispersion 19)
In a four-neck flask equipped with a thermometer, a stirrer, a reflux condenser and a nitrogen inlet tube, 350.0 parts by mass of UH-100, 33.4 parts by mass of DMPA, and 195.8 parts by mass of MEK were added and thoroughly stirred. Next, 358.1 parts by mass of H12MDI and 0.18 parts by mass of dibutyltin dilaurate were added and reacted at 75°C for 3 hours. After that, it was cooled to 50°C or less, 350.9 parts by mass of MEK and 36.9 parts by mass of 1,4-butanediol (BG) were added, and it was heated again to 75°C and reacted for 10 hours. After the reaction, 273.4 parts by mass of MEK and 5.0 parts by mass of methanol were added and stirred for 1 hour, and cooled to 40°C or less to obtain a urethane solution.

29.9 parts by mass of potassium hydroxide was added to the resulting urethane solution, and the acid groups were neutralized by stirring for 30 minutes. Next, 2,877.7 parts by mass of ion-exchanged water was gradually added under strong stirring to emulsify the urethane, and the MEK was then removed by vacuum distillation to synthesize an aqueous urethane resin dispersion 19 with a nonvolatile content of 30% by mass and a solid acid value of 40 mgKOH/g.

(Examples 1 to 9, Comparative Examples 1 to 10)
A pigment dispersion and an ink were prepared according to the following procedure.

(Production of Pigment Dispersion)
Into a 0.5 L jacketed tank of a mini planetary mixer (Aikosha mini-PLM Co., Ltd.), 50 parts by mass of C.I. Pigment Red 122 ("FASTOGEN Super Magenta RY" manufactured by DIC Corporation) and 10 parts by mass of a styrene-acrylic acid copolymer (weight average molecular weight 11,000, acid value 180 mgKOH/g) were sequentially charged, and the temperature of the jacketed tank was heated to 80°C, and the mixture was stirred for 10 minutes at a rotation speed of 80 rpm and a revolution speed of 25 rpm.

Next, with the temperature of the jacketed tank kept at 80°C, 5.29 parts by mass of a 34% by mass aqueous potassium hydroxide solution and 30 parts by mass of triethylene glycol were added to the composition, and the mixture was kneaded for 60 minutes at a rotation speed of 80 rpm and an orbital speed of 25 rpm to obtain a solid kneaded product.

100 parts by mass of ion-exchanged water and 10 parts by mass of triethylene glycol were added to the kneaded material, and the mixture was stirred and mixed for 10 minutes using a juicer mixer. By mixing the ion-exchanged water and Proxel-GXL (Lonza Japan Co., Ltd.), an aqueous pigment dispersion was obtained with a pigment concentration of 15.1% by mass, a triethylene glycol concentration of 12.0% by mass, and a Proxel-GXL concentration of 0.1% by mass.

(Production of pigment ink for inkjet printing)
19.9 parts by mass of the pigment dispersion obtained above, 3.3 parts by mass of the aqueous urethane resin dispersion obtained in Production Examples 1 to 19, 8.0 parts by mass of 2-pyrrolidinone, 8.0 parts by mass of triethylene glycol mono-n-butyl ether, 3.0 parts by mass of glycerin, 0.5 parts by mass of Surfynol 440 (manufactured by Air Products Inc.), and 57.3 parts by mass of ion-exchanged water were mixed to prepare a pigment ink for inkjet printing having a pigment concentration of 3.0% by mass and a urethane solids concentration of 1.0% by mass.

The following evaluations were carried out on the resulting pigment ink for inkjet printing.

(Storage stability of pigment inks for inkjet printing)
The pigment ink for inkjet printing obtained above was sealed in a polyethylene container and subjected to a heating test for 4 weeks in an incubator at 60° C. The change in viscosity after the heating test relative to the viscosity before the heating test was calculated based on the following formula, and the storage stability of the pigment ink was evaluated. The inks that were evaluated as having sufficient storage stability for practical use were evaluated as having A or B.
[(Viscosity of pigment ink after heating test)/(Viscosity of pigment ink before heating test)]×100

[Judgment criteria]
A: The rate of change in viscosity is less than 5%. B: The rate of change in viscosity is 5% or more and less than 15%. C: The rate of change in viscosity is 15% or more.

(Ejection stability of pigment ink for inkjet printing)
The water-based ink for inkjet printing obtained above was filled into a black ink cartridge of a commercially available inkjet printer ENVY4500 (manufactured by HP), and a nozzle check pattern was printed (first time). Next, solid printing was performed in monochrome mode over an area of 340 ^cm2 on one sheet of A4 paper with a print density setting of 100%. Next, a nozzle check test pattern was printed again (second time). The first and second nozzle check test patterns were compared to evaluate the clogging state of the ink ejection nozzles. Those that were evaluated as having A or B were evaluated as having sufficient ejection stability for practical use.

[Judgment criteria]
A: No missing parts in the printed pattern occurred in either the first or second nozzle check test pattern. B: The number of missing parts in the printed pattern confirmed in the first nozzle check test pattern was the same as the number of missing parts in the printed pattern confirmed in the second nozzle check test pattern.
C: The number of missing parts in the printed pattern confirmed in the second nozzle check test pattern was 1 to 5 more than the number of missing parts in the printed pattern confirmed in the first nozzle check test pattern.
D: The number of missing parts in the printed pattern confirmed in the second nozzle check test pattern was 6 or more greater than the number of missing parts in the printed pattern confirmed in the first nozzle check test pattern.

(Abrasion resistance)
The water-based ink for ink-jet printing obtained above was filled into a black ink cartridge of a commercially available ink-jet printer ENVY4500 (manufactured by HP Corporation), and solid printing was performed on the printing surface of photo printing paper (HP Advanced Photo Paper, manufactured by HP Corporation) with a print density setting of 100%.

After drying the print for one minute at room temperature, the print surface was rubbed once with the same paper as the printing paper using a Gakushin friction tester under a load of 200 g. The degree of rubbing of the color of the print surface, etc. was evaluated visually, and those that received an A or B were evaluated as having sufficient abrasion resistance for practical use.

[Judgment criteria]
A: There were no scratches on the printed surface, and no peeling of the coloring material was observed.
B: Although some scratches were observed on the printed surface, no peeling of the coloring material was observed.
C: Severe scratches were observed on the print surface, and peeling of coloring material was also observed.

(Washing resistance)
The entire surface of the cotton broadcloth was dyed with the water-based ink for inkjet printing obtained above, and then dried at 150°C for 5 minutes. The washing liquid prepared based on JISL0844:2011 was then heated to 50°C, and the cotton broadcloth was immersed (30 minutes). The washing liquid was then stirred in a food mixer for 1 minute, and the OD of the cotton broadcloth after stirring in the mixer was measured using an X-Rite integrating sphere spectrophotometer. The wash resistance index was calculated based on the following formula, and A was given if it was significantly better than ink without binder, B if it was good, C if it was equivalent, and D if it was inferior. The items that were rated A or B were evaluated as having sufficient wash resistance for practical use.
Washing durability index = (OD of cotton broadcloth after stirring)/(OD of cotton broadcloth before stirring)

The results are shown in Table 1.

As shown in the examples, when a urethane containing a crystalline polycarbonate diol with a molecular weight of 1000 to 3000, an alicyclic isocyanate, and a linear diamine as components and an acid value of 15 to 60 was used, the ink showed good results in terms of storage stability, ejection stability, abrasion resistance, and washability.

On the other hand, as shown in the comparative examples, when the ink contained any one of the other polymer diols, non-alicyclic isocyanates, and diamines with branched chains as constituents, at least one of the storage stability, ejection stability, abrasion resistance, and washing resistance of the ink was at a level not suitable for practical use. The same was true when the acid value was outside the range of the examples, or when a linear diol was used as a chain extender.

The binder resin composition for aqueous inkjet inks of the present invention is useful for printing on various recording media because it can achieve storage stability and ejection properties of the composition, as well as scratch resistance and washability of printed matter.

Claims (4)

The present invention comprises a urethane resin (I), a basic compound (II) and an aqueous medium (III),
the urethane resin (I) is a reaction product of a polyol (a), a polyisocyanate (b) and a polyamine compound (c);
The polyol (a) contains a crystalline polycarbonate diol (a1) and a diol having an acid group (a2),
The polyisocyanate (b) contains an alicyclic polyisocyanate (b1),
the polyamine compound (c) contains a linear diamine compound (c1);
the linear diamine compound (c1) is a linear diamine compound having 5 or less carbon atoms,
The acid value of the urethane resin (I) is 15 mgKOH/g or more and 60 mgKOH/g or less,
The binder resin composition for an aqueous ink-jet ink , wherein the basic compound (II) is a metal hydroxide . 2. The binder resin composition for aqueous ink-jet inks according to claim 1 , wherein the crystalline polycarbonate diol (a1) contains a crystalline polycarbonate polyol having a melting point of 40° C. or higher. An aqueous ink-jet ink comprising the binder resin composition for aqueous ink-jet inks according to claim 1 or 2 . A printed layer formed from the aqueous ink-jet ink according to claim 3 .