Urethane resin, water dispersion of binder resin, and aqueous ink

Abstract

To provide a urethane resin which enables formation of an image as a dry film excellent in adhesion, scratch resistance and ethanol resistance in a film made of various plastics such as polyethylene, polypropylene, and polyethylene terephthalate, can adjust a binder component for aqueous ink excellent in discharge stability, and is environmentally friendly.SOLUTION: There is provided a urethane resin for adjusting a water dispersion of a binder resin blended with aqueous ink for film printing. The urethane resin has a constitutional unit derived from a diol component containing polymer type diol (a1) and isosorbide (a2), a constitutional unit derived from a carboxy group-containing diol component, a constitutional unit derived from a diisocyanate component, and a constitutional unit derived from a diamine component, and a mass ratio (a1):(a2) of the polymer type diol (a1) to the isosorbide (a2) is 30:70 to 70:30, and an acid value is 10 to 50 mgKOH / g.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a urethane resin, a water dispersion of a binder resin, and a water-based ink. [Background technology]

[0002] Conventional oil-based inks for printing containing organic solvents are concerned about their environmental impact because the organic solvent is a volatile organic substance. For this reason, instead of organic solvents, aqueous inks using an aqueous medium, which is water or a mixed solvent of water and a water-soluble organic solvent, have been commercialized. Then, various images are printed by applying the aqueous ink to labels such as plastic films by printing methods such as gravure printing and flexographic printing. In addition, with the recent IT revolution, inkjet printing, which allows on-demand printing with aqueous inks, has been widely practiced. And, due to the high functionality of inkjet printing methods, aqueous inks are used in a wide range of applications, including personal use, office use, business use, recording, color display, and color photography.

[0003] In recent years, the scope of application of aqueous inks has expanded from consumer inkjet printers for office use and wide-format inkjet printers for large-format printing to inkjet printers, which are industrial equipment. Since the inkjet printing method does not require printing plates, it is useful as a method for obtaining small quantities of various industrial printed materials on demand. In addition, from the perspective of environmental consideration, inkjet printing methods using aqueous inks have been actively proposed.

[0004] Examples of industrial applications include sign displays, outdoor advertising, facility signs, displays, POP advertising, transportation advertising, packaging, containers, and labels. Examples of printing substrates (recording media) applicable to these applications include paper media such as paper, cardboard, photo paper, and inkjet paper; plastic media such as polyvinyl chloride, polyolefin, polyester, and nylon; and fabrics such as cotton cloth, ester cloth, nylon fabric, and nonwoven fabric. Furthermore, for industrial applications, on-demand printing that does not require a plate is mainstream, and high-speed printing suitability is required. Images recorded with aqueous inks containing dyes as coloring materials are poor in durability such as water resistance and light resistance, so aqueous inks containing pigments as coloring materials are used. In particular, printing on labels such as plastic films using aqueous inks containing pigments as coloring materials has attracted attention as an industrial application, and aqueous pigment inks for inkjet recording that can be printed on demand at high speed have been actively developed.

[0005] For example, inkjet inks have been proposed that contain an acrylic or urethane binder component capable of forming a film in order to record images with improved durability on plastic films (hereinafter also simply referred to as "films") (Patent Documents 1 and 2). In the case of aqueous pigment inks for inkjet recording, the pigment must be stably finely dispersed in the ink. For this reason, a pigment dispersion in which the pigment is stably finely dispersed over time using a surfactant or polymer dispersant, and an inkjet ink using this have been proposed (Patent Document 3). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 4157868 [Patent Document 2] Special Publication No. 2009-515007 [Patent Document 3] International Publication No. 2013 / 008691 Summary of the Invention [Problem to be solved by the invention]

[0007] The inkjet inks proposed in Patent Documents 1 to 3 contain binder resins to improve the durability of the recorded images. However, even when these inks are used, it is difficult to record images that are excellent in adhesion to the film and durability such as abrasion resistance.

[0008] Meanwhile, in view of the recent trend of global warming, the problem of carbon dioxide emissions, resource problems, and marine plastic problems, the importance of environmentally friendly technology is increasing. As the binder resin and polymer dispersant for dispersing the pigment blended in conventional water-based inks and water-based pigment dispersions, resins and the like synthesized using raw materials such as monomers derived from petroleum materials are used. In other words, images recorded with conventional water-based inks are mainly formed from materials derived from petroleum materials, and it cannot be said that environmentally friendly technology is necessarily applied.

[0009] In the past, inkjet printing technology was used for printing substrates such as containers and labels made of biodegradable plastics such as polylactic acid and polyhydroxyalkanoic acid. However, there was a problem in that environmentally friendly technology was not necessarily applied sufficiently to images recorded on such printing substrates.

[0010] The present invention has been made in consideration of the problems of the prior art, and an object of the present invention is to provide an environmentally friendly urethane resin capable of preparing a binder component for aqueous inks with excellent ejection stability, capable of forming an image that is a dry film with excellent adhesion, abrasion resistance, and ethanol resistance on films made of various plastics such as polyethylene, polypropylene, and polyethylene terephthalate. Another object of the present invention is to provide an aqueous dispersion of the binder resin obtained by using this urethane resin, and an aqueous ink. [Means for solving the problem]

[0011] That is, according to the present invention, the following urethane resin is provided. [1] A urethane resin for preparing an aqueous dispersion of a binder resin to be blended in an aqueous ink for film printing, the urethane resin having constitutional units derived from a diol component containing a polymeric diol (a1) having a number average molecular weight of 500 to 3,000 and an isosorbide (a2), constitutional units derived from at least one carboxy group-containing diol component selected from the group consisting of dimethylolpropanoic acid and dimethylolbutanoic acid, constitutional units derived from a diisocyanate component, and constitutional units derived from a diamine component, wherein the mass ratio of the polymeric diol (a1) to the isosorbide (a2) is (a1):(a2)=30:70 to 70:30, and the acid value is 10 to 50 mgKOH / g. [2] The urethane resin according to [1], wherein the polymer diol (a1) is at least one selected from the group consisting of polytetramethylene glycol, polyisosorbide carbonate diol, polyisosorbide tetramethylene carbonate diol, and polyisosorbide hexamethylene carbonate diol, the diisocyanate component is at least one selected from the group consisting of pentamethylene diisocyanate, hexamethylene diisocyanate, lysine diisocyanate, and isophorone diisocyanate, and the diamine component is at least one selected from the group consisting of pentamethylene diamine, hexamethylene diamine, and isophorone diamine.

[0012] According to the present invention, there is also provided an aqueous dispersion of the binder resin shown below. [3] An aqueous dispersion of a binder resin to be incorporated in an aqueous ink for film printing, comprising: an aqueous medium; and resin particles dispersed in the aqueous medium, the resin particles being formed by neutralizing, with an alkali, at least a portion of the carboxy groups in the urethane resin according to [1] or [2], wherein the resin particles have a volume-based cumulative 50% particle size of 20 to 150 nm.

[0013] Further, according to the present invention, there is provided the following water-based ink. [4] A water-based ink for film printing, comprising an aqueous dispersion of the binder resin described in [3] above. [5] A pigment, an aqueous medium, and a polymeric dispersant that disperses the pigment in the aqueous medium, the polymeric dispersant being an alkali-neutralized product of an acrylic polymer having an acid value of 50 to 200 mgKOH / g and a number average molecular weight of 5,000 to 20,000, the acrylic polymer comprising at least one structural unit (i) selected from the group consisting of (meth)acrylic acid, itaconic acid, and an itaconic acid monoalkyl ester, and a structural unit (i) derived from at least one structural unit selected from the group consisting of isobornyl (meth)acrylate, dodecyl (meth)acrylate, and octadecyl (meth)acrylate, and a structural unit (ii) derived from at least one selected from the group consisting of tetrahydrofurfuryl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, and isobutyl (meth)acrylate, wherein the total proportion of the structural units (i) to (iii) in all the structural units of the acrylic polymer is 80 mass% or more. [6] The water-based ink according to [4] or [5] above, which is for inkjet recording. Effect of the Invention

[0014] According to the present invention, it is possible to provide an environmentally friendly urethane resin capable of preparing a binder component for an aqueous ink having excellent ejection stability, capable of forming an image that is a dry film having excellent adhesion, abrasion resistance, and ethanol resistance on a film made of various plastics such as polyethylene, polypropylene, and polyethylene terephthalate. Furthermore, according to the present invention, it is possible to provide an aqueous dispersion of the binder resin obtained by using this urethane resin, and an aqueous ink. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] <Urethane resin> Hereinafter, the embodiment of the present invention will be described, but the present invention is not limited to the following embodiment. Various physical property values ​​in this specification are values ​​at room temperature (25°C) unless otherwise specified. One embodiment of the urethane resin of the present invention is a urethane resin for preparing an aqueous dispersion of a binder resin to be blended in an aqueous ink for film printing. The urethane resin of this embodiment has a constitutional unit derived from a diol component containing a polymer type diol (a1) having a number average molecular weight of 500 to 3,000 and isosorbide (a2), a constitutional unit derived from at least one carboxy group-containing diol component selected from the group consisting of dimethylolpropanoic acid and dimethylolbutanoic acid, a constitutional unit derived from a diisocyanate component, and a constitutional unit derived from a diamine component. In addition, the mass ratio of the polymer type diol (a1) to the isosorbide (a2) is (a1):(a2) = 30:70 to 70:30. The acid value of the urethane resin of this embodiment is 10 to 50 mgKOH / g. Hereinafter, the details of the urethane resin of this embodiment will be described.

[0016] (Diol component) The urethane resin has constitutional units derived from a diol component containing a polymer type diol (a1) and isosorbide (a2) having a number average molecular weight of 500 to 3,000. It is preferable that the diol component is substantially composed of only the polymer type diol (a1) and isosorbide (a2). Examples of the polymer diol (a1) include polyether diols such as polyethylene glycol, polypropylene glycol, polytetramethylene glycol, random structures or block structures thereof, bisphenol A ethylene oxide adducts, and bisphenol A propylene oxide adducts; polyester polyols such as polyneopentyl adipate and polycaprolactone having hydroxyl groups at both ends; polyolefin polyols such as polybutadiene polyols and polyisoprene polyols; polycarbonate diols such as polyhexamethylene carbonate, isosorbide carbonate diol, isosorbide tetramethylene carbonate diol, and isosorbide hexamethylene carbonate diol; and polysilicone polyols such as polydimethylsiloxane polyol.

[0017] However, when polyester polyol is used, the ester group may be easily hydrolyzed. When polyolefin polyol is used, the adhesion may be easily increased. Furthermore, when polysilicone polyol is used, the adhesion to the film may be slightly decreased. Therefore, from the viewpoint of forming an image excellent in hydrolysis resistance, flexibility, and adhesion, the polymer type diol (a1) is preferably polyether polyol and polycarbonate polyol.

[0018] The polymer type diol (a1) is preferably at least one selected from the group consisting of polytetramethylene glycol, polyisosorbide carbonate diol, polyisosorbide tetramethylene carbonate diol, and polyisosorbide hexamethylene carbonate diol. Polytetramethylene glycol is preferred from the viewpoints of resilience, abrasion resistance, hydrolysis resistance, and flexibility at low temperatures, and is also a type of environmentally friendly biomass polyol. Polyisosorbide carbonate diol, polyisosorbide tetramethylene carbonate diol, and polyisosorbide hexamethylene carbonate diol are compounds derived from isosorbide having a heterocyclic structure, and are therefore preferred from the viewpoints of high hardness and abrasion resistance. Isosorbide is a diol derived from plant raw materials such as starch and sugar, and butanediol and hexamethylene glycol derived from plant raw materials have also been developed. The polymer diol (a1) is preferably polytetramethylene glycol, which is relatively inexpensive and easily available, and more preferably polytetramethylene glycol derived from a plant raw material.

[0019] The number average molecular weight (Mn) of the polymer diol (a1) is 500 to 3,000, preferably 1,000 to 2,000. If the number average molecular weight of the polymer diol (a1) is less than 500, the urethane bonds in the urethane resin become too dense, and the flexibility of the image decreases. On the other hand, if the number average molecular weight of the polymer diol (a1) is more than 3,000, the image becomes too soft, and the adhesion to the film decreases.

[0020] In the present specification, the "number average molecular weight (Mn)" is a value calculated as polystyrene by gel permeation chromatography (GPC). A plurality of polymer-type diols (a1) having different number average molecular weights may be used in combination. However, it is preferable that each of the plurality of polymer-type diols (a1) has a number average molecular weight (Mn) in the range of 500 to 3,000.

[0021] Isosorbide (a2) is a heterocyclic diol having two secondary hydroxyl groups in the molecule. Since isosorbide (a2) has a highly rigid molecular structure, the scratch resistance of the image can be improved by introducing a structural unit derived from isosorbide (a2) into a urethane resin. In addition, since isosorbide (a2) has a condensed ring structure and contains an ether bond, the adhesion of the image to the film can be improved by introducing a structural unit derived from isosorbide (a2) into a urethane resin. Furthermore, since isosorbide (a2) is a diol derived from plant raw materials, it can be made into an environmentally friendly urethane resin.

[0022] The mass ratio of the polymer diol (a1) and the isosorbide (a2) is (a1):(a2)=30:70-70:30, preferably (a1):(a2)=40:60-60:40. By setting the mass ratio of the polymer diol (a1) and the isosorbide (a2) within the above range, the urethane bond formed by the reaction of the isosorbide (a2) and the diisocyanate component can be introduced densely and in large quantities into the urethane resin. Then, by using such a urethane resin, an image with improved scratch resistance and adhesion to the film can be formed. If the ratio of the isosorbide (a2) is too small, the urethane resin becomes soft and the adhesion of the image to the film decreases. On the other hand, if the ratio of the isosorbide (a2) is too large, the viscosity becomes too high during the synthesis of the urethane resin, and it becomes difficult to make it into an aqueous dispersion. Furthermore, the urethane resin becomes hard, and the flexibility of the image decreases, which may make it easier to detach from the film.

[0023] The diol component may contain a low molecular weight diol other than the polymer type diol (a1) and isosorbide (a2). Examples of the low molecular weight diol include polyhydric alcohols having 2 to 20 carbon atoms, such as ethylene glycol, 2-propylene glycol, 1,3-propylene glycol, 1,3-butanediol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol, and 1,4-bis(hydroxymethylcyclohexane). Polyfunctional alcohols such as glycerin and trimethylolpropane can also be used.

[0024] (Carboxy group-containing diol component) The urethane resin has a structural unit derived from at least one carboxyl group-containing diol component selected from the group consisting of dimethylolpropanoic acid and dimethylolbutanoic acid. By neutralizing the carboxyl group in this structural unit with an alkali, the urethane resin can be dispersed in water to form an aqueous dispersion. When a diol component containing an acidic group other than a carboxyl group, such as a phosphoric acid group or a sulfonic acid group, is used, the amine compound is difficult to volatilize when these acidic groups are neutralized with an amine compound, so the water resistance of the formed image is reduced. In contrast, by using a carboxyl group-containing diol component, the amine compound with the neutralized carboxyl group is easily volatilized, and the hydrophilicity of the image is reduced, thereby increasing the water resistance.

[0025] (Diisocyanate component) The urethane resin has a constituent unit derived from a diisocyanate component. Examples of the diisocyanate component include aromatic diisocyanates and aromatic alkyl diisocyanates such as toluene diisocyanate, diphenylmethane diisocyanate, naphthyl diisocyanate, xylylene diisocyanate, and tetramethyl xylylene diisocyanate; and aliphatic diisocyanates such as tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, dodecamethylene diisocyanate, trimethylhexamethylene diisocyanate, lysine diisocyanate, dicyclohexylene diisocyanate, norbornane diisocyanate, isophorone diisocyanate, and dimer acid diisocyanate. In addition, a biuret or a polyfunctional isocyanate having an isocyanurate structure can be used as necessary.

[0026] The diisocyanate component is preferably at least one selected from the group consisting of pentamethylene diisocyanate, hexamethylene diisocyanate, lysine diisocyanate, and isophorone diisocyanate. These diisocyanate components are aliphatic diisocyanates, and the use of these diisocyanate components can improve the light resistance and yellowing resistance of the image. Among them, pentamethylene diisocyanate, hexamethylene diisocyanate, and lysine diisocyanate all have small molecular weights, so that they can form dense urethane bonds by reaction with isosorbide (a2), thereby further improving the scratch resistance of the image and the adhesion to the film. Furthermore, the use of pentamethylene diisocyanate and lysine diisocyanate derived from plant raw materials can make the urethane resin environmentally friendly.

[0027] In addition, there are primary and secondary isocyanate groups in the molecule of isophorone diisocyanate. Since the secondary isocyanate group is less reactive than the primary isocyanate group, it suppresses abrupt reaction during polymerization. In addition, when isophorone diisocyanate having two isocyanate groups with different reactivity is used, it is easy to adjust the molecular weight of the obtained urethane resin. Furthermore, since it reacts preferentially with the hydroxyl group in the diol component rather than with the carboxy group in the carboxy group-containing diol, it is possible to suppress gelation due to polymerization. In addition, when isophorone diisocyanate is used, a cycloalkyl group can be introduced into the urethane resin, which can contribute to improving the physical properties of the urethane resin. Among them, it is preferable to use pentamethylene diisocyanate derived from plant raw materials in combination with isophorone diisocyanate, which can control the reaction, because the desired urethane resin can be easily synthesized.

[0028] (Diamine component) The urethane resin has a structural unit derived from a diamine component. The diamine component is a component used for controlling the molecular weight of the urethane resin and terminating the polymerization reaction, and can react with the diisocyanate component to form a urea bond and extend the chain of the urethane resin. Examples of the diamine component include ethylenediamine, trimethyldiamine, pentamethylenediamine, hexymethylenediamine, decanediamine, dodecanediamine, dicyclohexylmethanediamine, and isophoronediamine. Hydrazine and hydrazine compounds such as adipic acid dihydrazide can also be used as the diamine component.

[0029] The diamine component is preferably at least one selected from the group consisting of pentamethylenediamine, hexamethylenediamine, and isophoronediamine. When pentamethylenediamine and hexamethylenediamine are used, urea bonds are formed densely by reaction with isosorbide (a2), and the scratch resistance and adhesion to the film of the image can be further improved. In addition, when isophoronediamine is used, a cycloalkyl group can be introduced into the urethane resin, which can contribute to improving the physical properties of the urethane resin. Furthermore, by using pentamethylenediamine and hexamethylenediamine derived from plant raw materials, an environmentally friendly urethane resin can be obtained. In addition, when polymerizing the urethane resin, a monoamine component other than the diamine component, such as butylamine and monoethanolamine, can be used as a reaction stopper.

[0030] (urethane resin) The acid value of the urethane resin is 10 to 50 mgKOH / g, preferably 15 to 40 mgKOH / g. If the acid value is less than 10 mgKOH / g, it is difficult to prepare an aqueous dispersion even if neutralized with an alkali, and even if dispersed, the particle size becomes too large. On the other hand, if the acid value is more than 50 mgKOH / g, the resin tends to be water-soluble or the particle size becomes too small, and the viscosity of the aqueous dispersion may increase excessively. The acid value of the urethane resin can be measured by a titration method using phenolphthalein.

[0031] The number average molecular weight (Mn) of the urethane resin is preferably 10,000 to 1,000,000, and more preferably 10,000 to 50,000 from the viewpoints of the viscosity during synthesis and the physical properties of the printed matter. The molecular weight of the urethane resin is a value calculated in terms of polystyrene measured by gel permeation chromatography (GPC) using dimethylformamide (DMF) in which an appropriate amount of lithium bromide is dissolved as a developing solvent. The molecular weight distribution (PDI=weight average molecular weight (Mw) / number average molecular weight (Mn)) of the urethane resin is preferably 1.5 to 3.

[0032] The content of the urethane bond in the urethane resin is preferably 1 to 10 mol / kg, more preferably 1.5 to 6 mol / kg. The content of the urea bond in the urethane resin is preferably 0.5 mol / kg or less, more preferably 0.1 to 0.3 mol / g. By setting the contents of the urethane bond and the urea bond within the above ranges, respectively, it is possible to suppress the generation of coarse particles and to further improve the adhesion of the image to the film. The molecular weight of the urethane resin, the content of the urethane bond, and the content of the urea bond can all be adjusted by setting the compounding ratio of each component.

[0033] <Water dispersion of binder resin> One embodiment of the aqueous dispersion of the present invention is an aqueous dispersion of a binder resin to be incorporated in an aqueous ink for film printing, which contains an aqueous medium and resin particles formed by neutralizing at least a portion of the carboxyl groups in the urethane resin with an alkali and dispersed in the aqueous medium. The volume-based cumulative 50% particle size (median size (D50)) of the resin particles is 20 to 150 nm.

[0034] The aqueous dispersion of the present embodiment can be produced by synthesizing the above-mentioned urethane resin according to a conventional method, neutralizing at least a part of the carboxyl groups to self-emulsify the urethane resin and form resin particles. More specifically, first, a diol component, a diisocyanate component, a carboxyl group-containing diol component, and an organic solvent are mixed and heated. This allows a urethane prepolymer with an isocyanate terminal to be obtained. If necessary, a catalyst such as tin octanoate, bismuth 2-ethylhexanoate, zirconium salt, and a tertiary organic amine may be used. As the organic solvent, a water-soluble organic solvent that can be contained in the aqueous ink, which will be described later, can be used. Among them, it is preferable to use low-boiling point solvents such as acetone, tetrahydrofuran, and methyl ethyl ketone; and high-boiling point solvents such as amide-based solvents such as dimethylformamide and 3-methoxy-N,N-dimethylpropionamide. In addition, when pentamethylene diisocyanate is used, it may react with the carboxyl group of the carboxyl group-containing diol component to gel due to its high reactivity. For this reason, it is preferable to react the diol component with pentamethylene diisocyanate and then add and react the carboxy group-containing diol component, thereby controlling the reaction between pentamethylene diisocyanate and the carboxy group.

[0035] After the urethane prepolymer reaches a predetermined isocyanate equivalent, a mixture of alkali and water is added. A diamine component is added at the same time, or the diamine component is added after the addition of the mixture of alkali and water. Next, a chain extension reaction is carried out while vigorously stirring, and at least a part of the carboxyl group is neutralized to form resin particles. When a low boiling point solvent is used, the low boiling point solvent is distilled off by heating while reducing pressure as necessary, thereby obtaining a water dispersion of the desired urethane resin (binder resin). When a high boiling point solvent is used, the high boiling point solvent is not distilled off, and the water dispersion of the urethane resin (binder resin) can be obtained as it is. The content of the resin particles (urethane resin) in the obtained water dispersion is preferably 10 to 50 mass%, more preferably 20 to 30 mass%.

[0036] Examples of the alkali that neutralizes the carboxyl groups in the urethane resin include organic amines such as ammonia, triethylamine, diethanolamine, and dimethylaminoethanol; alkali metal hydroxides such as sodium hydroxide and potassium hydroxide; and the like. Among them, it is preferable to use high-boiling organic amines such as triethylamine and diethanolamine, which are less likely to volatilize in the solvent removal process. The amount of alkali may be an amount that can neutralize part or all of the carboxyl groups. Specifically, it may be an amount that can form resin particles with the desired particle size.

[0037] The average particle diameter of the resin particles in the aqueous dispersion (cumulative 50% particle diameter (D50) on a volume basis) is 20 to 150 nm, preferably 25 to 100 nm, and more preferably 30 to 80 nm. If the average particle diameter of the resin particles is less than 20 nm, the particle diameter is too small, and the viscosity of the ink increases. On the other hand, if the average particle diameter of the resin particles is more than 150 nm, clogging of the head may easily occur when applied to inkjet recording. The average particle diameter of the resin particles (cumulative 50% particle diameter (D50) on a volume basis) can be measured using a dynamic light scattering measuring device.

[0038] <Water-based ink> One embodiment of the aqueous ink of the present invention is an aqueous ink for film printing, which contains an aqueous dispersion of a binder resin prepared using the above-mentioned urethane resin. By blending the above-mentioned binder resin as a film-forming component, it is possible to obtain an aqueous ink with excellent ejection stability that can form an image, which is a dry film with excellent adhesion, abrasion resistance, and ethanol resistance, on various plastic films.

[0039] The aqueous ink of the present embodiment is useful as an aqueous gravure ink, an aqueous flexographic ink, an aqueous stationery ink, an aqueous silk screen ink, an aqueous inkjet ink, an ultraviolet-curable aqueous ink, etc. In particular, since the aqueous ink contains a binder resin containing a large number of carboxy groups, it is easy to wash and redissolve even after drying to a certain extent, and has good ejection stability, making it suitable as an inkjet recording ink.

[0040] (Water-based ink) The aqueous ink of the present embodiment may be a clear ink or a color ink containing a colorant. Examples of the colorant include dyes, pigments, colored beads, and metal powders. The colorant is appropriately selected and blended depending on the purpose of the printed matter, the print density, and the like. In addition, various additives may be contained in the aqueous ink. Examples of the additives include surfactants, preservatives, organic solvents, leveling agents, surface tension adjusters, pH adjusters, ultraviolet absorbers, light stabilizers, antioxidants, fillers, waxes, thickeners, defoamers, antifungal agents, and antistatic agents.

[0041] The clear ink can be prepared, for example, by mixing and stirring water, a water-soluble organic solvent, an aqueous dispersion of a binder resin, various additives, etc. to homogenize, and then filtering the mixture through a filter to remove foreign matter, dust, etc. Color inks containing a dye as a colorant can also be prepared in the same manner as the clear ink.

[0042] Color inks containing water-insoluble colorants such as pigments and colored beads can be prepared using a dispersion obtained by dispersing these colorants with a polymer dispersant. Color inks can also be prepared using self-dispersing pigments. Self-dispersing pigments are pigments in which acidic or basic groups are bonded to the surface of the pigment.

[0043] A polymer dispersant (also referred to as a "pigment dispersant") is a component for dispersing a pigment in an aqueous medium. A vinyl polymer can be used as the polymer dispersant. Monomers constituting the polymer dispersant include aromatic vinyl monomers such as styrene, vinyl toluene, and vinyl naphthalene; acrylate monomers such as butyl acrylate and 2-ethylhexyl acrylate; methyl methacrylate, propyl methacrylate, isopropyl methacrylate, butyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, hexyl methacrylate, cyclohexyl methacrylate, trimethylcyclohexyl methacrylate, t-butylcyclohexyl methacrylate, octyl methacrylate, 2-ethylhexyl methacrylate, decyl methacrylate, isodecyl methacrylate, dodecyl methacrylate, tetradecyl methacrylate, hexadecyl methacrylate, octadecyl methacrylate, and the like. methacrylate-based monomers such as dicyclopentenyl methacrylate, dicyclopentanyl methacrylate, adamantyl methacrylate, benzyl methacrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 4-hydroxybutyl methacrylate, methoxyethyl methacrylate, ethoxyethyl methacrylate, butoxyethyl methacrylate, ethoxyethoxyethyl methacrylate, butoxyethoxyethyl methacrylate, polyethylene glycol monomethyl ether methacrylate, dimethylaminoethyl methacrylate, and diethylaminoethyl methacrylate; vinyl ester-based monomers such as vinyl acetate; and heterocyclic vinyl monomers such as vinylpyridine and vinylimidazole.

[0044] Specific examples of polymer dispersants include styrene-acrylic acid copolymer, styrene-maleic acid copolymer, styrene-ethyl acrylate-acrylic acid copolymer, styrene-acrylic acid-ethoxyethyl acrylate copolymer, styrene-methacrylic acid copolymer, styrene-methacrylic acid-2-hydroxyethyl methacrylate copolymer, benzyl methacrylate-methacrylic acid copolymer, styrene-methacrylic acid-dimethylaminoethyl methacrylate-butyl acrylate copolymer, styrene-maleic acid-polyethylene glycol propylene glycol monobutyl ether monoamine amidation copolymer of maleic acid, and styrene-methyl methacrylate-2-ethylhexyl methacrylic acid copolymer.

[0045] A further preferred embodiment of the aqueous ink for film printing further comprises a pigment, an aqueous medium, and a polymeric dispersant for dispersing the pigment in the aqueous medium.

[0046] (Pigments) As the pigment, organic pigments and inorganic pigments can be used. Examples of organic pigments include chromatic pigments such as phthalocyanine, azo, azomethine azo, azomethine, anthraquinone, perinone-perylene, indigo-thioindigo, dioxazine, quinacridone, isoindoline, isoindolinone, diketopyrrolopyrrole, quinophthalone, and indanthrene; carbon black pigments such as furnace black, lamp black, acetylene black, and channel black; black pigments derived from plants such as bamboo charcoal and binchotan charcoal; and biomass carbon black pigments obtained from vegetable oils. Examples of inorganic pigments include extender pigments, titanium oxide pigments, iron oxide pigments, and spinel pigments.

[0047] Unless the printed matter (image) requires hiding power, it is preferable to use organic fine particle pigments. When a printed matter showing high definition and transparency is required, it is preferable to use pigments that have been finely milled by wet grinding such as salt milling or dry grinding. Considering the avoidance of nozzle clogging, it is preferable to use organic pigments with an average particle size of 0.2 μm or less, from which particles over 1.0 μm have been removed, or inorganic pigments with an average particle size of 0.4 μm or less.

[0048] Examples of pigments, listed by Color Index (CI) number, are: CI Pigment Yellow 12, 13, 14, 17, 20, 24, 74, 83, 86, 93, 94, 95, 97, 109, 110, 117, 120, 125, 128, 129, 137, 138, 139, 147, 148, 150, 151, 153, 154, 155, 166, 168, 175, 180, 181, 185, 191; CI Pigment Orange 16, 36, 43, 51, 55, 59, 61, 64, 71, 73; CI Pigment Red 4, 5, 9, 23, 48, 49, 52, 53, 57, 97, 112, 122, 123, 14 4, 146, 147, 149, 150, 166, 168, 170, 176, 177, 180, 184, 185, 192, 202, 207, 214, 215, 216, 217, 220, 221, 223, 224, 226, 227, 228, 238, 240, 242, 254, 255, 264, 269, 272; CI Pigment Violet 19, 23, 29, 30, 37, 40, 50; CI Pigment Blue 15, 15:1, 15:3, 15:4, 15:6, 22, 60, 64; CI Pigment Green 7, 36; CI Pigment Black 7; CI Pigment White 6; and the like.

[0049] Among these, from the viewpoints of suitability for inkjet recording and color development, dispersibility, weather resistance, and the like, preferred are yellow pigments such as CI Pigment Yellow 74, 83, 109, 128, 139, 150, 151, 154, 155, 180, 181, and 185; red pigments such as CI Pigment Red 122, 170, 176, 177, 185, and 269, and CI Pigment Violet 19 and 23; blue pigments such as CI Pigment Blue 15:3, 15:4, and 15:6; black pigments such as CI Pigment Black 7; and white pigments such as CI Pigment White 6.

[0050] (aqueous medium) The aqueous ink contains an aqueous medium which is a mixed solvent of water and a water-soluble organic solvent. Examples of the water-soluble organic solvent include alcohol-based solvents such as ethanol and isopropanol; ether-based solvents such as tetrahydrofuran; polyhydric glycol-based solvents such as ethylene glycol, propylene glycol, glycerin, and diethylene glycol; glycol ether-based solvents such as propyl glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, diethylene glycol monobutyl ether, triethylene glycol monobutyl ether, dipropylene glycol monomethyl ether, tripropylene glycol monomethyl ether, and tripropylene glycol monomethyl ether t-butyl ether; amide-based solvents such as pyrrolidone, N-methylpyrrolidone, 3-methoxy-N,N-dimethylpropionamide, and 3-butoxy-N,N-dimethylpropionamide; carbonate-based solvents such as ethylene carbonate; sulfur-based solvents such as dimethyl sulfoxide and sulfolane; and urea-based solvents such as dimethylimidazolidinone and tetramethylurea.

[0051] Polyhydric alcohol solvents, glycol ether solvents, and amide solvents are preferred from the viewpoints of safety, wettability, moisture retention, volatility, etc. These water-soluble organic solvents may be used as the solvent when producing the polymer dispersant.

[0052] (Polymer dispersant) The polymer dispersant is preferably an alkali neutralized product of an acrylic polymer. The acrylic polymer preferably has a constitutional unit (i) derived from at least one selected from the group consisting of (meth)acrylic acid, itaconic acid, and itaconic acid monoalkyl ester, a constitutional unit (ii) derived from at least one selected from the group consisting of isobornyl (meth)acrylate, dodecyl (meth)acrylate, and octadecyl (meth)acrylate, and a constitutional unit (iii) derived from at least one selected from the group consisting of tetrahydrofurfuryl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, and isobutyl (meth)acrylate.

[0053] The structural unit (i) is a structural unit having a carboxy group. By neutralizing the carboxy group in the structural unit (i) with an alkali, the polymer dispersant can be dissolved in an aqueous medium.

[0054] The monomer constituting the structural unit (ii) is a hydrophobic monomer having an alkyl group having 10 or more carbon atoms. The structural unit (ii) is adsorbed to the pigment by hydrophobic interaction. The proportion of the structural unit (ii) in all the structural units of the acrylic polymer is preferably 5 to 80 mass%, more preferably 10 to 50 mass%. Since the structural unit (ii) is composed of a monomer having an alkyl group having a large number of carbon atoms, it has high compatibility with the above-mentioned urethane resin having a structural unit derived from a diol component containing isosorbide (a2) used as a binder resin. Therefore, the aqueous ink using this acrylic polymer and urethane resin in combination is less likely to separate components, and can record clear and highly glossy images.

[0055] The structural unit (iii) is a structural unit that forms the main skeleton of the acrylic polymer. Among them, the use of tetrahydrofurfuryl (meth)acrylate having a cyclic ether group is preferable because it improves adhesion to the film and has high compatibility with the above-mentioned urethane resin having a structural unit derived from a diol component containing isosorbide (a2).

[0056] The monomers constituting the acrylic polymer are preferably materials derived from plant raw materials. Itaconic acids are preferably monomers derived from biomass obtained by fermentation. The alcohol forming the ester group of the itaconic acid monoalkyl ester is preferably biomass ethanol obtained by fermentation. Isobornyl (meth)acrylate is preferably a monomer prepared by a conversion reaction between camphene obtained from pine resin and (meth)acrylic acid. Dodecyl (meth)acrylate and octadecyl (meth)acrylate are preferably esters of long-chain alcohols obtained by reducing long-chain carboxylic acids such as coconut oil. Tetrahydrofurfuryl (meth)acrylate is preferably an ester of tetrahydrofurfuryl alcohol obtained by hydrogenating fural obtained from corn. Ethyl (meth)acrylate is preferably an ester of ethanol obtained by fermenting starch or the like. Butyl (meth)acrylate and isobutyl (meth)acrylate are preferably esters of alcohols with 4 carbon atoms obtained by cracking castor oil.

[0057] The total proportion of the structural units (i) to (iii) in all structural units of the acrylic polymer is preferably 80% by mass or more, and more preferably 90% by mass or more. The acrylic polymer is preferably substantially composed of only the structural units (i) to (iii). By making the total proportion of the structural units (i) to (iii) 80% by mass or more, it is possible to make the polymer dispersant more environmentally friendly.

[0058] The acid value of the acrylic polymer is preferably 50 to 200 mgKOH / g, more preferably 60 to 150 mgKOH / g. If the acid value of the acrylic polymer is less than 50 mgKOH / g, it is difficult to dissolve in water even when neutralized with an alkali, and the function as a polymer dispersant may not be fully exhibited. On the other hand, if the acid value of the acrylic polymer is more than 200 mgKOH / g, the water resistance and ethanol resistance may be reduced due to too many carboxyl groups. The acid value of the acrylic polymer can be controlled by adjusting the ratio of the structural unit (i).

[0059] The number average molecular weight of the acrylic polymer is preferably 5,000 to 20,000, and more preferably 6,000 to 15,000. If the number average molecular weight of the acrylic polymer is less than 5,000, even if it is adsorbed to the pigment, it is likely to be detached due to its high water solubility, and it may be difficult to improve the dispersion stability. On the other hand, if the number average molecular weight of the acrylic polymer exceeds 20,000, the viscosity of the ink may be easily increased excessively, and the ink may become thixotropic.

[0060] In the presence of an azo initiator such as azobisisobutyronitrile or a peroxide initiator such as benzoyl peroxide, an acrylic polymer can be obtained by bulk polymerization of a monomer alone, emulsion polymerization, or solution polymerization using a water-soluble organic solvent to be blended in the ink. The obtained acrylic polymer can then be neutralized with an alkali to obtain a polymer dispersant, which is a neutralized product of the acrylic polymer. Note that a solution of the polymer dispersant may be mixed with a pigment, and then the polymer dispersant may be precipitated by adding it to a poor solvent or treating it with an acid, and the pigment may be treated or encapsulated to prepare a polymer-treated pigment.

[0061] As the polymerization method, living radical polymerization is preferred because it can make the molecular weight uniform and the dispersion performance uniform.Specific examples include nitroxide-mediated polymerization (NMP method), atom transfer radical polymerization (ATRP method), reversible addition-fragmentation chain transfer polymerization (RAFT method), organotellurium living radical polymerization (TERP method), reversible transfer catalyzed polymerization (RTCP method), and reversible catalyst-mediated polymerization (RCMP method).

[0062] The acrylic polymer may be any of polymers having a higher structure such as random copolymers, block copolymers, graft copolymers, gradient copolymers, star polymers, and dendrimers. Among them, the acrylic polymer is preferably an AB block copolymer having an A chain, which is a water-insoluble polymer block, and a B chain, which is a water-soluble polymer block. The water-insoluble A chain is adsorbed to the pigment, so that the polymer dispersant is less likely to be detached from the pigment. The B chain dissolves in water, and the dispersion stability of the pigment can be maintained for a long period of time due to steric hindrance and electrical repulsion. Even if the ink dries in the recording head, it can be quickly redissolved due to the presence of the water-soluble B chain, and the dispersion state of the pigment can be restored to the original state. The AB block copolymer can be synthesized by a living radical polymerization method. Among them, it is preferable to synthesize it by the RTCP method or the RCMP method, which is easy to control the structure.

[0063] (binder resin) The aqueous ink contains an aqueous dispersion of the binder resin described above. The aqueous ink may further contain a binder resin (other binder resin) other than the binder resin described above. As the other binder resin, a styrene-acrylic resin, an acrylic resin, a urethane resin composed of other monomers, a polyester resin, etc. can be used. These resins can be added to the aqueous ink in the form of an emulsion or aqueous dispersion. Among them, it is preferable to use an acrylic resin composed of the same monomer as the monomer constituting the polymer dispersant as the other binder resin because it has good compatibility with the polymer dispersant and the binder resin (urethane resin).

[0064] (Water-based ink for inkjet recording) It is preferable to prepare an aqueous ink for inkjet recording using a pigment dispersion liquid in which a pigment is previously dispersed in an aqueous medium with a polymeric dispersant. The content of the organic pigment in the pigment dispersion liquid is preferably 1 to 30 mass %, more preferably 10 to 25 mass %. The content of the inorganic pigment in the pigment dispersion liquid is preferably 5 to 70 mass %, more preferably 30 to 50 mass %. The amount of the polymeric dispersant in the pigment dispersion liquid is preferably 1 to 100 mass parts, more preferably 5 to 50 mass parts, relative to 100 mass parts of the pigment.

[0065] The content of the pigment in the aqueous ink for inkjet recording prepared using this pigment dispersion is preferably 1 to 20% by mass, more preferably 2 to 10% by mass. The content of the binder resin in the aqueous ink for inkjet recording is preferably 10 to 300 parts by mass, more preferably 50 to 200 parts by mass, relative to 100 parts by mass of the pigment. The content of the water-soluble organic solvent in the aqueous ink may be appropriately set so as to suit the ejection method of the recording device to be used. Examples of additives to be contained in the aqueous ink for inkjet recording include the additives described above. Among them, it is preferable to use an alkali for adjusting the pH; a silicone-based, acetylene glycol-based, fluorine-based, alkylene oxide-based, and hydrocarbon-based surfactant; a preservative; a wax component; a leveling agent; and the like.

[0066] The viscosity of the aqueous ink for inkjet recording is adjusted to an appropriate viscosity that allows the ink to be ejected from the nozzles of a recording head depending on the type of pigment, etc. In particular, the viscosity of the aqueous ink at 25°C is preferably 2.9 to 3.3 mPa·s, and more preferably 3.0 to 3.2 mPa·s. By achieving such a low viscosity, images can be recorded even using existing inkjet recording devices. The binder component used in the aqueous ink of this embodiment is an emulsion in which the amount of the component dissolved in water is small, and therefore the viscosity of the aqueous ink can be reduced.

[0067] The pH of the aqueous ink for inkjet recording is preferably 7.0 to 10.0, and more preferably 7.5 to 9.5. If the pH is less than 7.0, the binder resin may be easily precipitated and the pigment may be easily aggregated. On the other hand, if the pH is more than 10.0, the ink may be difficult to handle due to its strong alkalinity.

[0068] The surface tension of the aqueous ink for inkjet recording is appropriately set depending on the performance of the inkjet recording device, etc. The surface tension of the aqueous ink for inkjet recording is, for example, preferably 15 to 45 mN / m, and more preferably 20 to 40 mN / m.

[0069] (film) The aqueous ink of the present embodiment is an aqueous ink for film printing. As the film serving as the printing substrate, a plastic film formed of various resins such as polyolefin, polyester, polyamide, polyvinyl halide, cellulose, polystyrene, polymethacrylate, polyacrylonitrile, polycarbonate, polyimide, polyvinyl acetal, and polyvinyl alcohol can be used.

[0070] Examples of polyolefin resins include low-density polyethylene, medium-density polyethylene, high-density polyethylene, polypropylene, polyα-olefin, polyethylene vinyl acetate, polyethylene vinyl alcohol, and polycycloolefin. Examples of polyester resins include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, and polylactic acid. Examples of polyamide resins include nylon 6, nylon 66, and nylon 610. Examples of polyvinyl halide resins include polyvinyl chloride, polyvinylidene chloride, and polyfluoroethylene. Among them, it is preferable to use polyester resin films formed of polyethylene terephthalate and the like, which are inexpensive and easily available, highly versatile, and frequently used in the market; and polyolefin resin films, which are generally difficult to form a printed film (image) with excellent adhesion and abrasion resistance, and it is more preferable to use polyethylene resin films and polypropylene resin films.

[0071] The plastic film may be unstretched or may be stretched by uniaxial stretching, biaxial stretching, or the like. The surface (printed surface) of the plastic film may be untreated or may be surface-treated by plasma treatment, corona treatment, radiation treatment, silane coupling treatment, or the like. The plastic film may have a single-layer structure or a multi-layer structure, and may be aluminum-vapor-deposited or transparently vapor-deposited. The thickness of the plastic film is preferably 1 to 500 μm, and more preferably 5 to 200 μm. The plastic film may be colored with a pigment or dye, or may contain a reinforcing filler such as carbon black, silica, calcium carbonate, glass fiber, or cellulose nanofiber. EXAMPLES

[0072] The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples. In the examples and comparative examples, "parts" and "%" are by mass unless otherwise specified.

[0073] <Production of urethane resin and aqueous dispersion> Example 1 Into a reaction vessel whose inside had been replaced with nitrogen gas, 250 parts of polytetramethylene ether glycol (trade name "BiоPTMG1000", manufactured by Mitsubishi Chemical Corporation, number average molecular weight 1,000), 250 parts of isosorbide, 117 parts of dimethylolpropionic acid, and 436 parts of tetrahydrofuran (THF) were placed. The mixture was heated to 50°C and stirred until the system became homogenous, after which 692 parts of isophorone diisocyanate (IPDI) was added. The mixture was heated to 80°C and reacted, and when the specified NCO% was reached, 436 parts of THF was added.

[0074] After cooling to an internal temperature of 50°C, 88 parts of triethylamine was added and stirred uniformly. After confirming that the system was uniform, a mixture of 3,891 parts of ion-exchanged water and 17 parts of ethylenediamine was added with strong stirring, emulsified and chain-extended, and then heated to 65°C while reducing the pressure to distill off THF, to obtain an aqueous dispersion U-1 (solid content 25%) containing resin particles formed of urethane resin. The acid value of the urethane resin was 37 mgKOH / g. The average particle size (median size (D50)) of the resin particles measured using a laser diffraction scattering type particle size distribution measuring device was 75 nm.

[0075] (Examples 2 to 10, Comparative Examples 1 to 4) Aqueous dispersions U-2 to 10 and HU-1 to 4 containing resin particles formed from a urethane resin (solid content 25%) were obtained in the same manner as in Example 1, except that the formulations (unit: parts) were as shown in the upper rows of Tables 1 and 2. The physical properties of the obtained aqueous dispersions are shown in the lower rows of Tables 1 and 2.

[0076] The meanings of the abbreviations in Tables 1 and 2 are as follows: A1: Polytetramethylene ether glycol, product name "BioPTMG1000" (manufactured by Mitsubishi Chemical Corporation), Mn 1,000, bio content 95% A2: Polytetramethylene ether glycol, product name "BioPTMG2000" (manufactured by Mitsubishi Chemical Corporation), Mn 2,000, bio content 95% A3: Polycarbonate polyol, product name "Benebiol NL1010DB" (manufactured by Mitsubishi Chemical Corporation), Mn 1,000, bio content 22% A4: Polycarbonate polyol, product name "Benebiol NL2010DB" (manufactured by Mitsubishi Chemical Corporation), Mn 2,000, bio content 21% A5: Polycarbonate polyol, product name "Benebiol NL3010DB" (manufactured by Mitsubishi Chemical Corporation), Mn 3,000, bio content 21% A6: Polyisosorbide tetramethylene carbonate polyol, product name "Benebiol HS0830B" (manufactured by Mitsubishi Chemical Corporation), Mn800, bio content 35%) A7: Polyisosorbide hexamethylene carbonate polyol, product name "Benebiol HS0840H" (manufactured by Mitsubishi Chemical Corporation), Mn800, bio content 37%) A8: Isosorbide B1: Isophorone diisocyanate (IPDI) B2: Pentamethylenediamine (bio content 71%) B3: Lysine diisocyanate (bio content 78%) B4: Hexamethylene diisocyanate C1: Dimethylolpropionic acid C2: Dimethylolbutanoic acid D1: Ethylenediamine D2: Pentamethylenediamine D3: Isophoronediamine E1: Tetrahydrofuran (THF) F1: Ion-exchanged water G1: Triethylamine G2: Dimethylaminoethanol

[0077] TIFF2025015225000001.tif184170

[0078] TIFF2025015225000002.tif148170

[0079] <Production of pigment dispersants> (Production Example 1) 100 parts of diethylene glycol monobutyl ether (BDG) were placed in a reaction vessel, and the vessel was heated to 80°C by bubbling nitrogen. In a separate vessel, 20 parts of ethyl methacrylate (EMA) (methacrylate synthesized using ethanol obtained by fermentation), 30 parts of isobornyl methacrylate (IBXMA), 30 parts of tetrahydrofurfuryl methacrylate (THFMA) (methacrylate synthesized using furfuryl alcohol obtained from corn), 20 parts of methacrylic acid, and 1.5 parts of 2,2-azobisisobutyronitrile (AIBN) were placed and stirred to obtain a uniform monomer solution. The obtained monomer solution was dropped into the reaction vessel over 2 hours. One hour after the dropwise addition, 1.5 parts of AIBN were added, and the mixture was allowed to react for another 5 hours at 80°C. After cooling, a mixture of 11.6 parts of 28% ammonia water and 62.7 parts of ion-exchanged water was added to obtain an aqueous solution of pigment dispersant G-1, which is a light brown transparent polymer solution. The resulting pigment dispersant G-1 (polymer) had an Mn of 12,600, a PDI of 2.05, and an acid value of 130.0 mgKOH / g. The aqueous solution of the pigment dispersant G-1 had a pH of 8.7 and a solid content of 36.5%.

[0080] (Production Example 2) BDG 283.1 parts, THFMA 59.6 parts, IBXMA 59.6 parts, iodine 2.0 parts, 2,2-azobis(4-methoxy-2,4-dimethylvaleronitrile) (trade name "V-70", Fujifilm Wako Pure Chemical Industries, Ltd.) (V-70) 3.6 parts, and N-iodosuccinimide (NIS) 0.1 parts were placed in a reaction vessel. The reaction vessel was heated to 45°C while bubbling nitrogen, and polymerization was carried out for 4 hours to form an A chain. A portion of the reaction solution was sampled, and the Mn of the A chain measured by gel permeation chromatography (GPC) was 5,100, the PDI was 1.21, and the polymerization rate was about 100%.

[0081] Next, a mixture of 119 parts of THFMA and 30.2 parts of methacrylic acid was added, and polymerization was carried out at 45°C for 4 hours to form B chains, obtaining an AB block copolymer in which B chains were extended from A chains. The resulting AB block copolymer had an Mn of 10,700, a PDI of 1.31, and an acid value of 73.0 mgKOH / g. The conversion calculated from the solid content was approximately 100%. The acid value of the B chain calculated taking into account the degree of polymerization was 132.0 mgKOH / g.

[0082] After cooling the polymerized solution to room temperature, a mixture of 23.4 parts of 28% ammonia water and 118.5 parts of water was added to obtain a light brown transparent polymer solution, an aqueous solution of pigment dispersant G-2. The pH of the aqueous solution of pigment dispersant G-2 obtained was 9.2, and the solid content was 41.1%.

[0083] <Production of Water-Based Ink for Inkjet Recording> Example 11 To 864 parts of ion-exchanged water, 411 parts of an aqueous solution of pigment dispersant G-1 (150 parts of polymer) and 600 parts of CI Pigment Blue 15:3 (PB15:3, manufactured by Dainichi Seika Chemicals Co., Ltd.) were added, and the mixture was thoroughly stirred and mixed with a dissolver to obtain a mixture. The obtained mixture was dispersed at a peripheral speed of 7 m / s using a horizontal media disperser (product name "Dyno Mill 0.6 liter multi-lab", manufactured by Shinmaru Enterprises, zirconia bead diameter: 0.5 mm) to thoroughly disperse the pigment in the mill base. After centrifugal separation (7,500 rpm, 20 minutes), the mixture was filtered through a 10 μm membrane filter to remove coarse particles. The concentration was adjusted by adding ion-exchanged water to obtain a blue aqueous pigment dispersion B-1 with a pigment concentration of 14%.

[0084] 16.0 parts of the aqueous dispersion U-1 obtained in Example 1, 28.6 parts of the aqueous pigment dispersion B-1, 18.0 parts of propylene glycol, 0.5 parts of a surfactant (product name "Silface SAG503A", manufactured by Nissin Chemical Industry Co., Ltd.), 0.7 parts of polyethylene wax, and 36.2 parts of water were mixed. After thorough stirring, the mixture was filtered through a membrane filter with a pore size of 5 μm to obtain ink I-1, which is an aqueous ink for inkjet recording. The viscosity of the obtained ink I-1 at 25° C. was 3.2 mPa s.

[0085] Example 12 To 517.5 parts of ion-exchanged water, 182.5 parts of an aqueous solution of pigment dispersant G-2 (75.0 parts of polymer) and 300 parts of CI Pigment Blue 15:3 (PB15:3, manufactured by Dainichiseika Color & Chemicals Co., Ltd.) were added, and the mixture was thoroughly stirred and mixed with a dissolver to obtain a mixture. A blue aqueous pigment dispersion B-2 with a pigment concentration of 14% was obtained in the same manner as in Example 11 described above, except that the obtained mixture was used. Then, ink I-2, which is an aqueous ink for inkjet recording, was obtained in the same manner as in Example 11 described above, except that the aqueous dispersion U-2 obtained in Example 2 and the aqueous pigment dispersion B-2 obtained were used. The viscosity of the obtained ink I-2 at 25°C was 2.9 mPa·s.

[0086] (Examples 13 to 20, Comparative Examples 5 to 8) Inks I-2 to 10 and HI-1 to 4, which are water-based inks for inkjet recording, were obtained in the same manner as in Example 11, except that the types of water dispersions and water-based pigment dispersions shown in Table 3 were used. The viscosity at 25° C. of each of the obtained inks is shown in Table 3.

[0087] <Evaluation> An inkjet recording device with a plate heater (product name "MMP825H", manufactured by Mastermind) and the following printing substrates were prepared. Then, images were recorded on each printing substrate using each of the prepared inks to obtain printed matter. Specifically, the printing substrate was heated using a plate heater so that the surface temperature was 55°C, and then each ink was applied to record an image. After that, the substrate was placed in a thermostatic chamber at 90°C for 10 minutes to dry, and a printed matter was obtained. [Printing base material] OPP film (polypropylene film, manufactured by Futamura Chemical Co., Ltd., thickness 50 μm) PET film (polyethylene terephthalate film, manufactured by Futamura Chemical Co., Ltd., thickness 50 μm)

[0088] (Discharge stability) The state of ink ejection during image recording was visually observed, and the ink ejection stability was evaluated according to the following evaluation criteria. The results are shown in Table 3. ◯: No discharge failure was observed. Δ: A small amount of splashing was observed in addition to the ink droplets. ×: Ink stopped being ejected midway, or scattering of dots was observed.

[0089] (Appearance of printed matter) The appearance of the resulting print was visually observed and evaluated according to the following evaluation criteria. ◯: No streaks or unevenness were observed, and a uniform image was recorded. ×: Streaks or unevenness were observed.

[0090] (Adhesion) Cellophane tape was pressed firmly against the image and then peeled off. The degree of peeling of the image from the film was visually observed, and the adhesion of the image was evaluated according to the following evaluation criteria. .DELTA.: No peeling at all. ○: Slight peeling. Δ: The peeled area was smaller than the area that did not peel. ×: The peeled area was larger than the non-peeled area.

[0091] (Abrasion resistance (dry and wet abrasion resistance)) A dry rub test was conducted by moving a dry white cloth back and forth over the surface of the image 100 times with a weight of 500g, and a wet rub test was conducted by moving a water-dampened white cloth back and forth over the surface of the image 100 times with a weight of 200g using a Gakushin-type rub fastness tester (product name "RT-300", manufactured by Daiei Kagaku Co., Ltd.). The degree of peeling of the image after the rub test was visually observed, and the rub resistance of the image (dry rub resistance and wet rub resistance) was evaluated according to the following evaluation criteria. .DELTA.: No peeling at all. ○: Slight peeling. Δ: The peeled area was smaller than the area that did not peel. ×: The peeled area was larger than the non-peeled area.

[0092] (Ethanol resistance) A 70% ethanol solution was dropped onto the image surface, and after leaving it for 10 seconds, the image was rubbed back and forth with a cotton swab. The number of times it took for the coating to peel off was counted, and the ethanol resistance of the image was evaluated according to the following evaluation criteria. ◎: 20 or more times ○: 10 to less than 20 times △: 5 to less than 10 times ×: Peeled off immediately or less than 5 times

[0093] TIFF2025015225000003.tif98170 [Industrial Applicability]

[0094] The aqueous ink of the present invention is suitable as an aqueous flexographic ink for use in label printing and printing on packaging containers. Furthermore, since the aqueous ink of the present invention has excellent ejection stability, it is useful as an aqueous ink for inkjet recording compatible with high-speed printing, and is suitable as an ink for producing commercial printed matter such as packaging using a medium such as film.

Claims

1. A urethane resin for preparing an aqueous dispersion of a binder resin to be incorporated in an aqueous ink for film printing, comprising: A structural unit derived from a diol component including a polymer type diol (a1) having a number average molecular weight of 500 to 3,000 and isosorbide (a2), A structural unit derived from at least one carboxy group-containing diol component selected from the group consisting of dimethylolpropanoic acid and dimethylolbutanoic acid; A structural unit derived from a diisocyanate component, and a structural unit derived from a diamine component, the mass ratio of the polymer diol (a1) to the isosorbide (a2) is (a1):(a2)=30:70 to 70:30; A urethane resin having an acid value of 10 to 50 mgKOH / g.

2. the polymeric diol (a1) is at least one selected from the group consisting of polytetramethylene glycol, polyisosorbide carbonate diol, polyisosorbide tetramethylene carbonate diol, and polyisosorbide hexamethylene carbonate diol; The diisocyanate component is at least one selected from the group consisting of pentamethylene diisocyanate, hexamethylene diisocyanate, lysine diisocyanate, and isophorone diisocyanate; 2. The urethane resin according to claim 1, wherein the diamine component is at least one selected from the group consisting of pentamethylenediamine, hexamethylenediamine, and isophoronediamine.

3. A water dispersion of a binder resin to be incorporated in a water-based ink for film printing, comprising: An aqueous medium; and resin particles formed by neutralizing at least a portion of the carboxy groups in the urethane resin according to claim 1 or 2 with an alkali, the resin particles being dispersed in the aqueous medium; The aqueous dispersion of the binder resin, wherein the resin particles have a cumulative 50% particle size based on volume of 20 to 150 nm.

4. A water-based ink for film printing, comprising the water dispersion of the binder resin according to claim 3.

5. The ink composition further comprises a pigment, an aqueous medium, and a polymeric dispersant for dispersing the pigment in the aqueous medium; the polymer dispersant is an alkali-neutralized product of an acrylic polymer having an acid value of 50 to 200 mgKOH / g and a number average molecular weight of 5,000 to 20,000; The acrylic polymer comprises a structural unit (i) derived from at least one selected from the group consisting of (meth)acrylic acid, itaconic acid, and an itaconic acid monoalkyl ester; A structural unit (ii) derived from at least one selected from the group consisting of isobornyl (meth)acrylate, dodecyl (meth)acrylate, and octadecyl (meth)acrylate; and (iii) a structural unit derived from at least one selected from the group consisting of tetrahydrofurfuryl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, and isobutyl (meth)acrylate, 5. The water-based ink according to claim 4, wherein the total proportion of the structural units (i) to (iii) in all structural units of the acrylic polymer is 80 mass % or more.

6. The water-based ink according to claim 5, which is for ink-jet recording.

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