Binder component for water-based ink and water-based ink

Abstract

Provided is an environmentally friendly binder component for aqueous inks that can form a dry coating such as an image with excellent adhesion and abrasion resistance even on substrates such as polypropylene substrates and polyethylene substrates that are generally difficult to form a coating with high adhesion. A binder component for aqueous inks, which is an A-B block copolymer comprising a water-insoluble polymer chain A and a polymer chain B, wherein the polymer chain B has a structural unit derived from methacrylic acid, the A-B block copolymer contains 80% by mass or more of a structural unit derived from a methacrylate derived from a biomaterial, contains 40% by mass or more of a structural unit derived from isobornyl methacrylate, has a number average molecular weight of 10,000 to 23,000, has an acid value of 25 to 100 mgKOH / g, and has a glass transition temperature of 90°C or more.

Description

Technical Field

[0001] The present invention relates to a binder component for water-based ink and a water-based ink using the binder component. Background Art

[0002] Inkjet printing is used in many fields such as personal use, office use, business use, recording, color display, and color photography due to its high functionality. Furthermore, in recent years, its application range has expanded from existing consumer inkjet printers for office use and wide-format inkjet printers for large-format printing to inkjet printers for industrial use. Since inkjet printing does not require a plate for image printing, it is suitable as a printing method that can obtain a small amount of a variety of industrial printed materials as needed. It should be noted that inkjet printing using water-based inkjet inks has been actively proposed due to environmental considerations.

[0003] As industrial uses, there are, for example, logo display, outdoor advertising, facility logo, display, POP advertising, traffic advertising, packaging, containers, labels and the like. As printing substrates (storage media) applied to these uses, there can be listed: paper media such as paper, cardboard, photo paper, and special inkjet paper; plastic media such as polyvinyl chloride, polyolefin, polyester, and nylon; fabrics such as cotton cloth, ester cloth, nylon cloth, and non-woven fabrics; etc. Furthermore, in the case of industrial uses, on-demand printing without a plate is the mainstream, and high-speed printing adaptability is required. In addition, images recorded with aqueous inkjet inks containing dyes as coloring materials lack durability such as water resistance and light resistance, so aqueous inkjet inks containing pigments as coloring materials are used.

[0004] Here, in order to record a printed image with improved durability, an inkjet ink to which an acrylic or polyurethane binder component capable of forming a coating is added is proposed (Patent Documents 1 and 2). In addition, it is necessary to stably microdisperse the pigment in an aqueous pigment inkjet ink, and a pigment dispersion liquid in which a surfactant or a polymer dispersant is used to stably microdisperse the pigment over time, and an inkjet ink using the same are proposed (Patent Document 3).

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent No. 4157868

[0008] Patent Document 2: Japanese Patent Application No. 2009-515007

[0009] Patent Document 3: International Publication No. 2013 / 008691 Summary of the invention

[0010] Problem that the invention aims to solve

[0011] However, even with the inkjet inks using the pigment dispersions proposed in Patent Documents 1 to 3, it is difficult to record images having excellent durability such as adhesion and abrasion resistance.

[0012] However, in view of the current global warming trend, carbon dioxide emission problems, resource problems and marine plastic problems, etc., the importance of technologies that take the environment into consideration, such as energy saving, recycling and environmentally friendly materials, has increased. In such a case, as a dispersant for dispersing pigments in existing aqueous inkjet inks and aqueous pigment dispersions, a polymer dispersant synthesized from raw materials such as monomers derived from petroleum materials has been used. That is, since the image recorded with the existing aqueous inkjet ink is formed by materials derived from petroleum materials, it cannot be said that it is necessarily suitable for environmentally friendly technologies. Printing substrates such as containers and labels formed by biodegradable plastics such as polylactic acid and polyhydroxyalkanoates are suitable for inkjet printing, but on the other hand, the image recorded on such a printing substrate has the problem of not being suitable for environmentally friendly technologies.

[0013] The present invention is made in view of the problems of such prior art, and its subject is to provide a binder component for aqueous ink that takes the environment into consideration and can form a dry coating such as an image with excellent adhesion and abrasion resistance even on substrates such as polypropylene substrates and polyethylene substrates, which are generally difficult to form a coating with high adhesion, and an aqueous ink using the binder component.

[0014] Solutions for solving problems

[0015] According to the present invention, the following aqueous ink binder component is provided.

[0016] [1] A binder component for an aqueous ink, which is a polymer satisfying the following characteristics (1) to (3):

[0017] [Feature (1)]:

[0018] is an AB block copolymer comprising a polymer chain A and a polymer chain B, wherein:

[0019] The content of the structural unit derived from a biomaterial-derived methacrylate is 80% by mass or more, wherein the biomaterial-derived methacrylate is at least one selected from the group consisting of ethyl methacrylate, tetrahydrofurfuryl methacrylate, isobornyl methacrylate, dodecyl methacrylate and octadecyl methacrylate,

[0020] The content of the structural unit derived from isobornyl methacrylate is 40% by mass or more,

[0021] The number average molecular weight of the AB block copolymer is 10,000 to 23,000.

[0022] The acid value is 25-100 mgKOH / g.

[0023] The glass transition temperature is 90°C or higher.

[0024] [Feature (2)]:

[0025] The polymer chain A is the following polymer block:

[0026] contains 30% by mass or more of a structural unit derived from isobornyl methacrylate,

[0027] Containing 80% by mass or more of the structural unit of the methacrylate derived from a biomaterial,

[0028] The number average molecular weight is 5000~18000,

[0029] The glass transition temperature is above 80°C.

[0030] The molecular weight distribution is 1.6 or less.

[0031] [Feature (3)]:

[0032] The polymer chain B is the following polymer block:

[0033] comprising structural units derived from methacrylic acid,

[0034] contains 50% by mass or more of a structural unit derived from isobornyl methacrylate,

[0035] Containing 50% by mass or more of a structural unit derived from a methacrylic acid ester derived from a biomaterial,

[0036] The acid value is 50~150mgKOH / g,

[0037] The number average molecular weight is 3000-15000.

[0038] Furthermore, the present invention provides the following aqueous inks.

[0039] [2] A water-based ink comprising: water, a colorant, a water-soluble organic solvent, and the water-based ink binder component described in [1].

[0040] [3] The water-based ink according to [2] above, further comprising polyethylene wax.

[0041] [4] The aqueous ink according to the above [2] or [3], wherein the water-soluble organic solvent comprises propylene glycol and at least one selected from the group consisting of diethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether and dipropylene glycol monomethyl ether, and the content of the water-soluble organic solvent is 3 to 30% by mass.

[0042] [5] The water-based ink according to any one of [2] to [4], which is used for printing on at least one of a polypropylene-based substrate and a polyethylene-based substrate.

[0043] Effects of the Invention

[0044] The present invention provides an environmentally friendly binder component for aqueous ink that can form a dry coating such as an image with excellent adhesion and abrasion resistance even on substrates such as polypropylene substrates and polyethylene substrates, which are generally difficult to form a coating with high adhesion, and an aqueous ink using the same. DETAILED DESCRIPTION

[0045] <Binder component for water-based ink>

[0046] The following describes the embodiments of the present invention, but the present invention is not limited to the following embodiments. The various physical property values ​​in this specification are values ​​at room temperature (25° C.) unless otherwise specified. Hereinafter, the "binder component for water-based ink" is also simply referred to as the "binder component", and the "water-based ink" is also simply referred to as the "ink".

[0047] One embodiment of the binder component for aqueous ink of the present invention is a polymer satisfying the following characteristics (1) to (3). The binder component of the present invention will be described in detail below.

[0048] [Feature (1)]:

[0049] is an AB block copolymer comprising a polymer chain A and a polymer chain B, wherein:

[0050] The content of the structural unit derived from a methacrylate derived from a biomaterial is 80% by mass or more, wherein the methacrylate derived from a biomaterial is at least one selected from the group consisting of ethyl methacrylate, tetrahydrofurfuryl methacrylate, isobornyl methacrylate, dodecyl methacrylate, and octadecyl methacrylate,

[0051] The content of the structural unit derived from isobornyl methacrylate is 40% by mass or more,

[0052] The number average molecular weight of the AB block copolymer is 10,000 to 23,000,

[0053] The acid value is 25-100 mgKOH / g.

[0054] The glass transition temperature is 90°C or higher.

[0055] [Feature (2)]:

[0056] The polymer chain A is the following polymer block:

[0057] contains 30% by mass or more of a structural unit derived from isobornyl methacrylate,

[0058] Containing 80% by mass or more of the structural unit of the methacrylate derived from a biomaterial,

[0059] The number average molecular weight is 5000~18000,

[0060] The glass transition temperature is above 80°C.

[0061] The molecular weight distribution is 1.6 or less.

[0062] [Feature (3)]:

[0063] The polymer chain B is the following polymer block:

[0064] comprising structural units derived from methacrylic acid,

[0065] contains 50% by mass or more of a structural unit derived from isobornyl methacrylate,

[0066] Containing 50% by mass or more of a structural unit derived from a methacrylic acid ester derived from a biomaterial,

[0067] The acid value is 50~150mgKOH / g,

[0068] The number average molecular weight is 3000-15000.

[0069] (Feature (1))

[0070] The binder component of the present embodiment is an AB block copolymer comprising a polymer chain A (hereinafter also referred to as "A chain") and a polymer chain B (hereinafter also referred to as "B chain"). The A chain is a substantially water-insoluble polymer block. The B chain is a polymer block comprising a structural unit derived from methacrylic acid. Since the B chain has a carboxyl group derived from methacrylic acid, it is a polymer block that is substantially water-soluble by neutralizing at least a portion of the carboxyl group with a base.

[0071] The content of the structural unit of the methacrylate derived from the biological material of the AB block copolymer is more than 80 mass %, preferably more than 90 mass %, more preferably 100 mass %. Since it is a polymer comprising a large number of structural units of methacrylate derived from biological material, it is a binder component considering the environment. In addition, since it is a polymer comprising a large number of structural units derived from methacrylate, it is possible to expect to record an image with a relatively high glass transition temperature (Tg) and improved thermal properties such as heat resistance. Further, methacrylate is more difficult to hydrolyze than acrylate, so it can be expected to be relatively stable in an aqueous liquid medium.

[0072] The methacrylate derived from a biomaterial is at least one selected from the group consisting of ethyl methacrylate, tetrahydrofurfuryl methacrylate, isobornyl methacrylate, dodecyl methacrylate, and octadecyl methacrylate. The methacrylate derived from a biomaterial is a methacrylate synthesized using an alcohol derived from a biomaterial as a material, and the ester residue containing oxygen of the ester bond other than the methacryloyl group is an alcohol residue derived from a biomaterial.

[0073] Ethyl methacrylate derived from biological materials is, for example, an ester of ethanol obtained by decomposing or fermenting starch or sugar, and methacrylic acid. Tetrahydrofurfuryl methacrylate derived from biological materials is, for example, an ester of tetrahydrofurfuryl alcohol obtained by hydrogenating furfural obtained from corn cobs, and methacrylic acid. Isobornyl methacrylate derived from biological materials is, for example, a methacrylate obtained by isomerizing α-pinene obtained from rosin and pine essential oil and then reacting camphene with methacrylic acid. Lauryl methacrylate and octadecyl methacrylate derived from biological materials are, for example, esters of long-chain alkanols obtained by hydrogenating and reducing long-chain alkanoic acids, which are fractions of fatty acids obtained by hydrolyzing oils such as palm kernel oil and coconut oil, and methacrylic acid.

[0074] Furthermore, in the AB block copolymer, the content of the structural unit derived from isobornyl methacrylate in the methacrylate derived from the biomaterial is 40% by mass or more, preferably 45% by mass or more, and more preferably 50% by mass or more. By setting the content of the structural unit derived from isobornyl methacrylate within the above range, a coating film having excellent adhesion and abrasion resistance can be formed.

[0075] The number average molecular weight (Mn) of the AB block copolymer is 10,000 to 23,000, preferably 11,000 to 20,000. By setting the number average molecular weight to the above range, a coating having excellent adhesion and friction resistance can be formed. When the number average molecular weight of the AB block copolymer is less than 10,000, the adhesion and friction resistance of the formed coating cannot be improved. On the other hand, when the number average molecular weight of the AB block copolymer is greater than 23,000, the viscosity of the aqueous ink prepared using the AB block copolymer as a binder component may be too high. The "number average molecular weight" and "weight average molecular weight" in this specification are both polystyrene-converted values ​​obtained by gel permeation chromatography.

[0076] The acid value of the AB block copolymer is 25 to 100 mgKOH / g, preferably 28 to 80 mgKOH / g. When the acid value is less than 25 mgKOH / g, it is difficult to disperse and emulsify in water. On the other hand, when the acid value is greater than 100 mgKOH / g, the viscosity sometimes increases excessively, and the water resistance of the formed coating and image decreases.

[0077] The glass transition temperature (Tg) of the AB block copolymer is 90°C or higher, preferably 100°C or higher. By setting the glass transition temperature (Tg) to 90°C or higher, it is expected that the heat resistance of the formed coating will be improved. It should be noted that there is no particular upper limit on the glass transition temperature (Tg) of the AB block copolymer, and it is usually set to 140°C or lower.

[0078] AB block copolymers are polymers whose structures are effectively controlled and can be produced, for example, by living polymerization, particularly living radical polymerization. Specifically, the production of AB block copolymers by living radical polymerization using an organic iodide as an initiating compound and an organic compound as a catalyst is preferred because environmentally friendly materials can be used and the degree of freedom in polymer design is high.

[0079] (Feature (2))

[0080] The polymer chain A (A chain) is a substantially water-insoluble polymer block. By including the A chain, a coating having excellent adhesion and abrasion resistance to the printed substrate can be formed. The A chain contains more than 30% by mass, preferably more than 40% by mass, of structural units of isobornyl methacrylate, a type of methacrylate derived from a biological material. In addition, the A chain contains more than 80% by mass, preferably more than 90% by mass, of structural units of methacrylate derived from the aforementioned biological material. When the content of structural units of methacrylate derived from a biological material in the A chain is less than 80% by mass, it is slightly insufficient from the perspective of environmental considerations.

[0081] The number average molecular weight (Mn) of the A chain is 5000 to 18000, preferably 6000 to 13000. By setting the number average molecular weight (Mn) of the A chain to the above range, an image (dried coating) with excellent adhesion to the printed substrate and excellent wipe resistance can be formed. When the number average molecular weight (Mn) of the A chain is less than 5000, the adhesion of the formed coating to the printed substrate is reduced. On the other hand, when the number average molecular weight (Mn) of the A chain is greater than 18000, the polymerization rate sometimes decreases and the molecular weight distribution tends to become wider. In addition, the glass transition temperature (Tg) of the A chain is above 80°C, preferably above 90°C.

[0082] The molecular weight distribution (PDI = weight average molecular weight (Mw) / number average molecular weight (Mn)) of the A chain is 1.6 or less, preferably 1.5 or less, and more preferably 1.4 or less. That is, the A chain is a polymer block with a relatively uniform molecular weight. When the molecular weight distribution (PDI) of the A chain is greater than 1.6, a polymer block outside the number average molecular weight (Mn) range is excessively included.

[0083] The A chain may further contain other structural units other than the structural unit derived from the methacrylic acid ester derived from the aforementioned biomaterial. Examples of other structural units include structural units derived from methacrylic acid ester derived from petroleum raw materials. Examples of the methacrylate derived from petroleum raw materials include methyl methacrylate, propyl methacrylate, isopropyl methacrylate, butyl methacrylate, isobutyl methacrylate, tert-butyl methacrylate, hexyl methacrylate, cyclohexyl methacrylate, trimethylcyclohexyl methacrylate, tert-butylcyclohexyl methacrylate, octyl methacrylate, 2-ethylhexyl methacrylate, decyl methacrylate, isodecyl methacrylate, dodecyl methacrylate, tetradecyl methacrylate, hexadecyl methacrylate, octadecyl methacrylate, dicyclopentenyl methacrylate, dicyclopentyl 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.

[0084] The A chain may further contain a structural unit derived from methacrylic acid as long as it is a water-insoluble polymer block. The content of the structural unit derived from methacrylic acid in the A chain is, for example, about 0.5 to 5% by mass.

[0085] (Feature (3))

[0086] The polymer chain B (B chain) is a polymer block including a structural unit derived from methacrylic acid, and at least a part of the carboxyl groups derived from the methacrylic acid are neutralized with a base to be ionized and substantially water-soluble.

[0087] The B chain contains 50% by mass or more, preferably 55% by mass or more, of a structural unit derived from isobornyl methacrylate, which is a type of methacrylate derived from a biomaterial. By containing the structural unit derived from isobornyl methacrylate in the above range, the glass transition temperature (Tg) of the AB block copolymer can be increased, and a film with improved heat resistance can be expected to be formed.

[0088] The B chain contains 50% by mass or more of the structural unit derived from the methacrylate derived from the aforementioned biomaterial, preferably 50 to 90% by mass, more preferably 50 to 85% by mass, and particularly preferably 60 to 85% by mass. The AB block copolymer having a B chain containing a structural unit derived from a methacrylate derived from a biomaterial in the above range is an environmentally friendly adhesive component.

[0089] The acid value of the B chain is 50 to 150 mgKOH / g, preferably 60 to 130 mgKOH / g. When the acid value of the B chain is less than 50 mgKOH / g, the B chain becomes difficult to dissolve in water, the stability of the particles when the AB block copolymer is made into an aqueous dispersion (emulsion) is impaired, and the resolubility of the ink becomes insufficient. On the other hand, when the acid value of the B chain is greater than 150 mgKOH / g, the viscosity of the ink sometimes increases excessively, and the water resistance of the formed coating and image is reduced.

[0090] The number average molecular weight (Mn) of the B chain is 3000 to 15000, preferably 4000 to 10000. By setting the number average molecular weight to the above range, stable particles can be formed when the AB block copolymer is made into an aqueous dispersion (emulsion). Furthermore, since the molecular weight of the B chain is relatively high, it can form a coating with improved durability such as friction resistance together with the A chain. When the number average molecular weight of the B chain is less than 5000, the stability of the particles when the AB block copolymer is made into an aqueous dispersion (emulsion) is impaired. On the other hand, when the number average molecular weight of the B chain is greater than 15000, the viscosity of the ink increases excessively, and the water resistance of the formed coating and image is reduced.

[0091] Examples of the base used to neutralize the carboxyl groups derived from methacrylic acid include ammonia; organic amines such as dimethylaminoethanol and triethylamine; alkali metal hydroxides such as sodium hydroxide and potassium hydroxide; etc. All carboxyl groups may be neutralized with the base, or part of the carboxyl groups may be neutralized within the range in which the B chain can be dissolved in water. Specifically, from the viewpoint of pH stability, etc., it is preferred that 90 mol% or more of the carboxyl groups are neutralized.

[0092] <Water-based ink>

[0093] One embodiment of water-based ink of the present invention contains water, colorant, water-soluble organic solvent, and aforementioned water-based ink binder component. The water-based ink of this embodiment is useful as, for example, water-based gravure ink, water-based flexible ink, water-based inkjet ink, and water-based stationery ink, etc. Below, the details of water-based ink of the present invention are described.

[0094] (water)

[0095] As water, it is preferable to use ion exchange water, distilled water, purified water, etc. The content of water in the ink is preferably 30 to 90% by mass based on the total amount of the ink.

[0096] (Colorant)

[0097] As the coloring agent, existing known dyes and pigments can be used. Among them, pigments are preferred from the viewpoints of water resistance, color development, color concentration and vividness. The pigment can be used in the form of a pigment dispersion dispersed in a dispersion medium such as a liquid medium containing an aqueous system, a polymer dispersant and a surfactant.

[0098] When a dye is used as a colorant, the content of the dye in the ink is preferably 0.5 to 30% by mass. When a pigment is used as a colorant, the content of the pigment in the ink is preferably 0.1 to 25% by mass, and more preferably 0.2 to 20% by mass.

[0099] As pigments, organic pigments and inorganic pigments known in the art used in water-based inks can be used. As organic pigments, phthalocyanine, azo, azomethine, anthraquinone, pyrene·perylene, indigo·thioindigo, dioxazine, quinacridone, isoindoline, isoindoline, pyrrolopyrrole dione, quinophthalone, indanthrene and other color pigments can be listed; furnace black, lamp black, acetylene black, channel black and other carbon black pigments; etc. As inorganic pigments, body pigments, titanium oxide pigments, titanium oxide pigments, spinel pigments and the like can be listed.

[0100] In addition to the case where the printed matter (image) requires hiding power, it is preferred to use organic microparticle pigments. In the case of printed matter that requires high definition and transparency, it is preferred to use pigments that have been finely ground by wet grinding or dry grinding such as salt milling. In consideration of avoiding nozzle clogging, it is preferred to use organic pigments with a number average particle size of 0.2 μm or less and inorganic pigments with a number average particle size of 0.4 μm or less, which have been removed from pigments with a particle size greater than 1.0 μm.

[0101] If specific examples of pigments are represented by color index (CI) numbers, 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, 144, 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; etc.

[0102] Among them, from the viewpoint of being suitable for aqueous ink for inkjet and having color development, dispersibility, and weather resistance, yellow pigments such as CI Pigment Yellow 74, 83, 109, 128, 139, 150, 151, 154, 155, 180, 181, and 185 are preferred; red pigments such as CI Pigment Red 122, 170, 176, 177, 185, 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 are preferred.

[0103] The pigment may be any of the following: an untreated pigment; a self-dispersible pigment having a functional group introduced on its surface; a surface-treated pigment treated with a coupling agent, an activator or a polymer, or a treated pigment encapsulated. A self-dispersible pigment is an easily dispersible pigment that has acidic groups such as carboxyl, sulfonic acid and phosphoric acid introduced on the surface of the pigment particles, and is made water-friendly by neutralizing these acidic groups, so that it can be dispersed in the ink even without using a pigment dispersant. In contrast, untreated pigments, surface-treated pigments and encapsulated pigments are preferably used in combination with a pigment dispersant.

[0104] The pigment is preferably used in the form of a pigment dispersion. As the pigment dispersant used in the pigment dispersion, for example, a vinyl polymer having a number average molecular weight of 1000 to 20000 and an acid value of 50 to 250 mgKOH / g neutralized by an alkaline substance is preferably used. The content of the pigment dispersant in the pigment dispersion is preferably 5 to 100 parts by mass, more preferably 10 to 50 parts by mass, relative to 100 parts by mass of the pigment.

[0105] The vinyl polymer preferably has acidic groups such as carboxyl, sulfonic acid, and phosphoric acid. The acidic groups such as carboxyl are neutralized with an alkaline substance to make them water-friendly, so that they can be finely dispersed or dissolved in the ink. The vinyl polymer with an acidic group contains a structural unit derived from a monomer with an acidic group. As monomers with an acidic group, there can be listed: (meth) acrylic acid, maleic acid (anhydride), itaconic acid (anhydride), styrene carboxylic acid, monomers formed by reacting (meth) acrylic acid ester monomers with hydroxyl groups with carboxylic anhydride, dibasic acid or polycarboxylic acid to form monoesterification, vinyl sulfonic acid, acrylamide methyl propane sulfonic acid, vinyl phosphoric acid, methacryloyloxyethyl phosphoric acid, etc.

[0106] Vinyl polymers usually further have structural units derived from other monomers other than the monomer having an acidic group. Examples of other monomers include aromatic vinyl monomers such as styrene, vinyl toluene, and vinyl naphthalene; (meth)acrylate monomers such as butyl (meth)acrylate and 2-ethylhexyl (meth)acrylate; vinyl ester monomers such as vinyl acetate; heterocyclic vinyl monomers such as vinyl pyridine and vinyl imidazole; and the like.

[0107] Examples of the vinyl polymer include styrene-acrylic acid copolymers, styrene-maleic acid copolymers, styrene-ethyl acrylate-acrylic acid copolymers, styrene-acrylic acid-ethoxyethyl acrylate copolymers, styrene-methacrylic acid copolymers, styrene-methacrylic acid-2-hydroxyethyl methacrylate copolymers, benzyl methacrylate-methacrylic acid copolymers, styrene-methacrylic acid-dimethylaminoethyl methacrylate-butyl acrylate copolymers, styrene-maleic acid-maleic acid polyethylene glycol propylene glycol monobutyl ether monoamine amidate copolymers, and styrene-methyl methacrylate-2-ethylhexyl methacrylate-methacrylic acid copolymers.

[0108] The number average molecular weight (Mn) of the vinyl polymer is preferably 1000 to 20000, more preferably 3000 to 15000, and particularly preferably 5000 to 13000. When the number average molecular weight of the vinyl polymer is less than 1000, the adsorption of the pigment may be insufficient, and the strength of the printed film formed may be reduced. On the other hand, when the number average molecular weight of the vinyl polymer is greater than 20000, the viscosity of the ink increases excessively and tends to exhibit non-Newtonian viscosity, and the ejection stability may be reduced when the ink is made into an inkjet ink.

[0109] The acid value of the vinyl polymer used as a pigment dispersant is preferably 50 to 250 mgKOH / g, more preferably 75 to 150 mgKOH / g, and particularly preferably 85 to 130 mgKOH / g. When the acid value of the vinyl polymer is less than 50 mgKOH / g, it may be difficult to dissolve in water even if neutralized with an alkaline substance, and the function as a pigment dispersant may be insufficient. On the other hand, when the acid value of the vinyl polymer is greater than 250 mgKOH / g, the water solubility may become too high. As a result, the viscosity of the ink increases excessively, and the amount of hydrophilic acidic groups such as carboxyl groups increases, so that the water resistance of the formed printed film may decrease.

[0110] The above-mentioned vinyl polymer can be synthesized by existing known methods. For example, in the presence of azo initiators such as azobisisobutyronitrile and peroxide initiators such as benzoyl peroxide, by bulk polymerization of monomers alone, emulsion polymerization, solution polymerization using a water-soluble organic solvent for inkjet ink, vinyl polymer can be obtained. Then, if the obtained vinyl polymer is neutralized with an alkaline substance, a pigment dispersant can be made. In addition, after the solution of the pigment dispersant is mixed with the pigment, it is added to a poor solvent or treated with an acid, so that the pigment dispersant is precipitated, and the pigment is treated or encapsulated to make a polymer-treated pigment. As a polymerization method for manufacturing vinyl polymers, an active free radical polymerization method is preferred. Vinyl polymers can be any of polymers with high-dimensional structures such as random copolymers, block copolymers, graft copolymers, gradient copolymers, star polymers, and dendritic compounds.

[0111] The vinyl polymer used as the pigment dispersant is preferably a block copolymer having a C chain and a D chain and satisfying the following characteristics (3-1) to (3-3). Such a block copolymer is preferred because of its good compatibility and affinity with the AB block copolymer used as the binder component.

[0112] (3-1) It contains 90% by mass or more of a structural unit derived from a methacrylate monomer and has a number average molecular weight of 3,000 to 20,000.

[0113] (3-2) The C chain has a structural unit (Ci), which is derived from at least one selected from the monomer group (i), wherein the monomer group (i) consists of methyl methacrylate, benzyl methacrylate, cyclohexyl methacrylate, tert-butyl cyclohexyl methacrylate, isobornyl methacrylate and tetrahydrofurfuryl methacrylate, and the content of the structural unit (Ci) in the C chain is 80% by mass or more, and the number average molecular weight of the C chain is 2000 to 10000 and the molecular weight distribution is 1.6 or less.

[0114] (3-3) The D chain has a structural unit (D) derived from methacrylic acid and a structural unit (Di), wherein the structural unit (Di) is derived from at least one selected from the monomer group (i), wherein the monomer group (i) consists of methyl methacrylate, benzyl methacrylate, cyclohexyl methacrylate, tert-butyl cyclohexyl methacrylate, isobornyl methacrylate and tetrahydrofurfuryl methacrylate, the content of the structural unit (Di) in the D chain is 80% by mass or more, and the acid value of the D chain is 70 to 250 mgKOH / g.

[0115] The C chain is a water-insoluble polymer chain and is a polymer block that is adsorbed on the pigment and encapsulated. The D chain is a polymer chain having a carboxyl group and is a water-soluble polymer block. The C chain is adsorbed on the pigment and the D chain is dissolved in water to prevent the pigment particles from approaching each other, so a high degree of dispersion stability can be imparted. In addition, the D chain is a water-soluble polymer block, and even if the ink dries, it can be dissolved again in the aqueous medium.

[0116] The number average molecular weight of the block copolymer is preferably 3000 to 20000, more preferably 4000 to 15000. If the number average molecular weight of the block copolymer is less than 3000, the dispersion stability may be insufficient. On the other hand, when the number average molecular weight of the block copolymer is greater than 20000, the viscosity of the ink may increase excessively, and the adsorption of the pigment may decrease.

[0117] The C chain has more than 80% by mass of structural units (Ci), and the structural units (Ci) are derived from at least one selected from the aforementioned monomer group (i), so the C chain has high compatibility with the AB block copolymer used as the first binder component and is not easy to aggregate or precipitate in the ink. The number average molecular weight of the C chain is 2000 to 10000, preferably 2500 to 7500. When the number average molecular weight of the C chain is less than 2000, the encapsulation of the pigment becomes insufficient and the dispersion stability is slightly reduced. On the other hand, when the number average molecular weight of the C chain is greater than 10000, the adsorption of the pigment is easily reduced and the encapsulation becomes difficult. The molecular weight distribution of the C chain is less than 1.6, preferably 1.2 to 1.5. That is, by making the molecular weight consistent to a certain extent, the adsorption of the pigment can be improved.

[0118] The D chain has a structural unit (D) and a structural unit (Di) derived from methacrylic acid, and the structural unit (Di) is derived from at least one selected from the aforementioned monomer group (i). Similarly to the C chain, the D chain also has a structural unit (Di) and the structural unit (Di) is derived from at least one selected from the aforementioned monomer group (i), so the compatibility of the D chain and the AB block copolymer used as a binder component is high. The above-mentioned block copolymer with C chain and D chain is synthesized by living free radical polymerization method, which can make the molecular weight consistent to a certain extent, and is therefore preferred.

[0119] The pigment dispersion can be prepared according to the existing known methods. For example, first, a mixture of pigment, pigment dispersant, water and water-soluble organic solvent is prepared. Then, a paint shaker, a ball mill, a grinder, a sand mill, a horizontal medium mill, a colloid mill, a roller mill, etc. are used to finely disperse the pigment to prepare the pigment dispersion. The obtained pigment dispersion is preferably prepared by using a centrifuge or a filter to remove coarse particles. Other additives may also be added as needed. The content of organic pigments in the pigment dispersion is preferably 1 to 30% by mass, more preferably 10 to 25% by mass. The content of inorganic pigments in the pigment dispersion is preferably 5 to 70% by mass, more preferably 30 to 50% by mass.

[0120] (Binder ingredients)

[0121] The ink of the present embodiment contains the aforementioned binder component. When the colorant is a pigment, the content of the binder component (solid content) in the ink is preferably 50 to 505 parts by mass, and more preferably 100 to 400 parts by mass, relative to 100 parts by mass of the pigment. When the content of the solid content of the binder component in the ink is less than 50 parts by mass relative to 100 parts by mass of the pigment, the adhesion and friction resistance of the formed printed coating and the plastic film are slightly insufficient. On the other hand, when the content of the solid content of the binder component in the ink is greater than 505 parts by mass relative to 100 parts by mass of the pigment, the pigment concentration is relatively reduced, so there is a situation where the color development of the image is slightly reduced. It should be noted that when the colorant is a dye, the content of the binder component (solid content) in the ink is preferably 20 to 505 parts by mass relative to 100 parts by mass of the dye.

[0122] (Water-soluble organic solvent)

[0123] The ink of this embodiment is useful as an ink for printing on a printed substrate such as a plastic film with low permeability. Therefore, it is preferable to use a water-soluble organic solvent that acts as a moisturizer and has good wettability to a printed substrate such as a plastic film with low permeability. Furthermore, it is preferable to use a water-soluble organic solvent that acts as a leveling agent on the surface of the printed substrate and also acts as a film-forming aid to improve the film-forming property of the binder component in the ink.

[0124] Examples of the water-soluble organic solvent include alcohol solvents such as methanol, ethanol, and isopropanol; ketone solvents such as acetone; alkylene glycol solvents such as ethylene glycol, diethylene glycol, propylene glycol, and dipropylene glycol; alkylene glycol monoalkyl ether solvents such as ethylene glycol methyl ether, diethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, dipropylene glycol monomethyl ether, and tripropylene glycol monomethyl ether; glycerol solvents such as glycerol, diglycerol, and ethylene oxide adducts of glycerol; amide solvents such as 2-pyrrolidone, N-methylpyrrolidone, 3-methoxy-N,N-dimethylpropionamide, and 3-butoxy-N,N-dimethylpropionamide; urea solvents such as tetramethylurea and dimethylimidazolidinone; carbonate solvents such as ethylene carbonate and dimethyl carbonate; and the like.

[0125] In the printed film formed by the binder component in the ink imparted to the printed substrate, when a large amount of water-soluble organic solvent remains, the water resistance of the printed film, the adhesion to the printed substrate and the friction resistance are reduced. In addition, when the binder component (AB block copolymer) is synthesized by a method such as solution polymerization, there is a case where the organic solvent used is directly mixed in the ink. Therefore, it is preferred to use a water-soluble organic solvent with high volatility to a certain extent. Therefore, the water-soluble organic solvent preferably includes propylene glycol (boiling point 188°C) and includes at least one selected from the group consisting of diethylene glycol monobutyl ether (boiling point 230°C), propylene glycol monomethyl ether (boiling point 121°C), propylene glycol monoethyl ether (boiling point 132.8°C), propylene glycol monopropyl ether (boiling point 150°C) and dipropylene glycol monomethyl ether (boiling point 189.6°C).

[0126] The content of the water-soluble organic solvent in the ink is preferably 3 to 30% by mass, more preferably 5 to 25% by mass, based on the total amount of ink. When the content of the water-soluble organic solvent is less than 3% by mass, the ink sometimes becomes easy to dry, and it is difficult to function as a leveling agent on the surface of the printed substrate such as a plastic film. On the other hand, when the content of the water-soluble organic solvent is greater than 30% by mass, the viscosity of the ink increases, the ejection of the ink decreases, and sometimes the stability of the ink is easily reduced. In addition, there are cases where the binder component is precipitated or the pigment agglomerates. Further, when the content of the water-soluble organic solvent is too much, the water-soluble organic solvent is likely to remain in the printed film, so it is easy to produce adhesion, and the physical properties of the image such as water resistance and friction resistance will be reduced.

[0127] (Wax ingredients)

[0128] The ink of this embodiment may further contain wax. Wax has a high affinity for printed substrates such as plastic films, so by using an ink containing wax, a printed film with further improved adhesion can be formed. In addition, wax sometimes separates from the binder component and oozes to the surface, so by using an ink containing wax, a printed film with further improved friction resistance can be formed.

[0129] Examples of the wax include polyethylene wax, polyolefin wax, and silicone wax. Among them, polyethylene wax is preferably used. Polyethylene wax has high hydrophobicity, so by using an ink containing polyethylene wax, a printed coating with excellent durability can be formed. Polyethylene wax can be used in the form of a dispersion (polyethylene wax emulsion) dispersed in water, for example. The content of polyethylene wax in the ink is preferably 0.1 to 2.5% by mass, and more preferably 0.3 to 1.5% by mass, based on the total amount of ink.

[0130] (Other additives)

[0131] The ink may further contain various known additives. Examples of the additives include surfactants, preservatives, organic solvents other than the aforementioned water-soluble organic solvents, leveling agents, surface tension regulators, pH regulators, ultraviolet absorbers, light stabilizers, antioxidants, dyes, fillers, thickeners, defoamers, mildew preventers, antistatic agents, metal particles, magnetic powders, and the like.

[0132] By making the ink contain a surfactant, the surface tension of the ink can be controlled. The surface tension of the ink is preferably 15 to 45 mN / m, and more preferably 20 to 40 mN / m. Examples of surfactants include silicone surfactants, acetylene glycol surfactants, fluorine surfactants, alkylene oxide surfactants, and hydrocarbon surfactants. Among them, silicone surfactants, acetylene glycol surfactants, and fluorine surfactants are preferred. The content of the surfactant in the ink is preferably 0 to 3.5% by mass, based on the total amount of the ink, and more preferably 0.01 to 2.0% by mass.

[0133] Examples of preservatives include sodium benzoate, benzimidazole, thiabendazole, potassium sorbate, sodium sorbate, sodium dehydroacetate, thiazosulfamide, and pyridinethioloxide. The content of the preservative in the ink is preferably 0.05 to 2.0% by mass, more preferably 0.1 to 1.0% by mass, based on the total amount of the ink.

[0134] (Manufacturing of water-based ink)

[0135] The target ink of the present embodiment can be obtained by mixing the above-mentioned various components in predetermined amounts, stirring them sufficiently using a disperser or the like, and then removing coarse particles and dirt through a filter.

[0136] (Physical properties of water-based ink)

[0137] The physical properties of the aqueous ink can be appropriately set according to the application and purpose. For example, when the aqueous ink is used as an inkjet ink, the viscosity can be adjusted to a suitable level that can be ejected from the nozzle of the recording head by the inkjet method according to the type of pigment, etc. The viscosity of the ink containing organic pigments is preferably 2 to 10 mPa·s. In addition, the viscosity of the ink containing inorganic pigments is preferably 5 to 30 mPa·s.

[0138] The pH of the ink is preferably 7.0 to 10.0, more preferably 7.5 to 9.5. When the pH of the ink is less than 7.0, the binder component may be easily precipitated and the pigment may be easily aggregated. On the other hand, when the pH of the ink is greater than 10.0, the ink becomes more alkaline and thus may become difficult to handle.

[0139] When used as an aqueous ink for inkjet, the surface tension of the ink is preferably set according to the performance of inkjet printing, etc. For example, the surface tension of the ink is preferably 15 to 45 mN / m, more preferably 20 to 40 mN / m.

[0140] (Printed substrate and printed matter)

[0141] By using the ink of this embodiment, a printed film or image having excellent adhesion and abrasion resistance can be formed on a printed substrate such as a plastic film having low permeability in addition to a common printed substrate. As the plastic constituting the plastic film, various resins such as polyolefin resins, polyester resins, polyamide resins, polyvinyl halide resins, cellulose resins, polystyrene resins, polymethacrylate resins, polyacrylonitrile resins, polycarbonate resins, polyimide resins, polyvinyl acetal resins, and polyvinyl alcohol resins can be cited.

[0142] As polyolefin resins, low-density polyethylene, medium-density polyethylene, high-density polyethylene, polypropylene, poly-α-olefins, polyethylene vinyl acetate, polyethylene vinyl alcohol, polycycloolefins, etc. can be listed. As polyester resins, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polylactic acid, etc. can be listed. As polyamide resins, nylon 6, nylon 66, nylon 610, etc. can be listed. As polyvinyl halide resins, polyvinyl chloride, polyvinylidene chloride, polyvinyl fluoride, etc. can be listed. Among them, it is preferred to print on a film made of polyolefin resin that is cheap and easy to obtain, and is usually difficult to form a printed film with excellent adhesion and friction resistance. More specifically, the ink of this embodiment is preferably used for printing on at least any printed substrate in a polypropylene substrate and a polyethylene substrate.

[0143] The plastic film used as the printed substrate may be unstretched or may be stretched by uniaxial stretching, biaxial stretching or the like. The surface (printing surface) of the plastic film may be untreated or may be subjected to surface treatments such as plasma treatment, corona treatment, radiation treatment, silane coupling treatment or the like. The plastic film may be a single-layer structure or a multi-layer structure, and may be subjected to aluminum vapor deposition or transparent vapor deposition. 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 pigments or dyes, and may also be added with reinforcing materials such as carbon black, silicon dioxide, calcium carbonate, glass fiber, and cellulose nanofibers.

[0144] By applying the ink of the present embodiment to stationery such as gravure printing, flexographic printing, inkjet printing, and markers, and imparting it to various printed substrates, a printed object (image formation) can be obtained. In the case of inkjet printing, an inkjet printer equipped with a recording head such as a thermal head or a piezoelectric head is used to impart ink to various printed substrates by an inkjet recording method, so that an image can be recorded (printed). Specifically, images can be recorded on printed substrates such as paper, photographic paper, photo glossy paper, polyolefin film, polyethylene terephthalate film, and other plastic films, fibers, cloth, ceramics, metals, and molded objects. The recorded image is a so-called dry film with excellent durability such as high chroma, high color rendering, adhesion, and friction resistance. That is, by using the ink of the present embodiment, a printed object with an environmentally friendly and carbon-neutral dry film containing biomaterial-derived components can be manufactured.

[0145] Example

[0146] The present invention is further described in detail below with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples unless it exceeds the gist of the present invention. Regarding the amounts of components, "parts" and "%" are by mass unless otherwise specified.

[0147] <Manufacturing of binder component (polymer emulsion)>

[0148] (Example 1)

[0149] In a reaction vessel equipped with a stirrer, a thermometer, a reflux tube, and a nitrogen inlet tube, 172.4 parts of diethylene glycol monobutyl ether (BDG), 1.0 parts of iodine, 3.7 parts of 2,2-azobis(4-methoxy-2,4-dimethylvaleronitrile) (trade name "V-70", manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) (V-70), 0.2 parts of N-iodosuccinimide (NIS), 50 parts of tetrahydrofurfuryl methacrylate (THFMA), and 50 parts of isobornyl methacrylate (IBXMA) were added. As THFMA, an ester of tetrahydrofurfuryl alcohol obtained by hydrogenating furfural obtained from corn cobs and the like and methacrylic acid was used. In addition, as IBXMA, a methacrylate obtained by isomerizing α-pinene obtained from rosin and pine essential oil and reacting camphene with methacrylic acid was used. While stirring while bubbling nitrogen, polymerization was carried out at 45°C for 4 hours to synthesize a polymer (A chain) to obtain a liquid containing a polymer. A portion of the sampled liquid was used to measure the molecular weight of the polymer by gel permeation chromatography (GPC) using tetrahydrofuran as a developing solvent. As a result, the number average molecular weight (Mn) of the polymer was 8500, and the molecular weight distribution (PDI = weight average molecular weight (Mw) / number average molecular weight (Mn)) was 1.33. In addition, the solid content of the liquid containing the polymer was 37.4%, and the polymerization conversion calculated from the solid content was about 100%. The Tg (60°C) of the homopolymer of THFMA, the Tg (155°C) of the homopolymer of IBXMA, and the glass transition temperature (Tg) of the polymer calculated from their constituent blending ratio are 102°C.

[0150] 2.0 parts of V-70, 13 parts of THFMA, 39 parts of IBXMA, and 13 parts of methacrylic acid (MAA) were added to a liquid containing a polymer (chain A) cooled to 40°C. After that, polymerization was carried out at 40°C for 4 hours to form a polymer (chain B), thereby obtaining a liquid containing an AB block copolymer. The polymerization was confirmed to be almost complete by measuring the solid content and the amount of residual monomers measured by gas chromatography (GC). The solid content of the liquid containing the AB block copolymer was about 50%, and the polymerization conversion was about 100%. The Mn of the AB block copolymer was 15000 and the PDI was 1.42. The peak of the A chain in GPC shifted to the high molecular weight side, confirming that an AB block copolymer was formed. That is, the Mn of the B chain was 6500. The acid value of the B chain calculated from the amount of MAA used was 130 mgKOH / g. The precipitate generated by adding a portion of the liquid containing the AB block copolymer to methanol was filtered, washed with methanol, and then dried to obtain a sample. The obtained sample was titrated with an ethanolic 0.1N potassium hydroxide solution to measure the acid value of the AB block copolymer. As a result, the acid value of the AB block copolymer was 52 mgKOH / g.

[0151] The liquid containing the AB block copolymer was neutralized by adding a mixture of 10.2 parts of 28% ammonia water and 334.7 parts of ion exchange water at room temperature, and then an appropriate amount of water was added to obtain a polymer emulsion (binder component E-1) having a polymer content of 25%.

[0152] (Examples 2 to 8, Comparative Examples 1 to 3)

[0153] A polymer emulsion (binder components E-2 to 8, H-1 to 3) having a polymer content of 25% was obtained in the same manner as in Example 1 except that various materials of the types and amounts (unit: parts) shown in Tables 1 and 2 were used. The physical properties of the polymers in the obtained binder components E-2 to 8, H-1 to 3 are shown in Tables 1 and 2. In addition, the meanings of the abbreviations in Tables 1 and 2 are as follows.

[0154] EMA: Ethyl methacrylate (esterified product of methacrylic acid and ethanol obtained by decomposing starch or sugar)

[0155] StMA: stearyl methacrylate (esterified product of methacrylic acid and stearyl alcohol obtained by hydrogenation reduction of oleic acid, which is a fatty acid fraction obtained by hydrolyzing oils such as palm kernel oil and coconut oil)

[0156] LMA: Lauryl methacrylate (esterified product of methacrylic acid and lauryl alcohol obtained by hydrogenation reduction of lauric acid, which is a fatty acid fraction obtained by hydrolyzing oils such as palm kernel oil and coconut oil)

[0157] Table 1

[0158]

[0159] Table 2

[0160]

[0161] <Preparation of Pigment Dispersant>

[0162] (Preparation Example 1)

[0163] 100 parts of BDG were added to a reaction vessel equipped with a stirring device, a thermometer, a reflux tube, and a nitrogen inlet tube, and nitrogen was bubbled and heated to 80°C. 20 parts of styrene (St), 15 parts of methyl methacrylate (MMA), 15 parts of EMA, 20 parts of 2-ethylhexyl methacrylate (2EHMA), 15 parts of 2-hydroxyethyl methacrylate (HEMA), 15 parts of MAA, and 1.5 parts of 2,2-azobisisobutyronitrile (AIBN) were added to another container, and a uniform monomer solution was prepared by stirring. The prepared monomer solution was dripped into the reaction vessel over 2 hours. After dripping for 1 hour, 1.5 parts of AIBN were added, and the mixture was further reacted at 80°C for 5 hours. After cooling, a mixture of 11.6 parts of 28% ammonia water and 62.7 parts of ion exchange water was added to the solution, and a light brown transparent polymer solution was obtained. The obtained polymer solution was used as an aqueous solution of pigment dispersant G-1. The pH of the aqueous solution of the obtained pigment dispersant G-1 was 8.7, and the solid content was 36.5%. The pigment dispersant G-1 (polymer) had an Mn of 13,200, a PDI of 2.15, and an acid value of 65.2 mgKOH / g.

[0164] (Preparation Example 2)

[0165] 283.1 parts of BDG, 59.6 parts of THFMA, 59.6 parts of IBXMA, 2.0 parts of iodine, 3.6 parts of V-70, and 0.1 parts of NIS were added to a reaction vessel equipped with a stirring device, a thermometer, a reflux tube, and a nitrogen inlet tube. While stirring while bubbling nitrogen, polymerization was performed at 45° C. for 4 hours to synthesize a polymer (chain A) and obtain a liquid containing a polymer. The Mn of the polymer (chain A) obtained by measuring a part of the sampled liquid was 5100, the PDI was 1.21, and the polymerization conversion rate was about 100%.

[0166] A mixture of 119 parts of THFMA and 30.2 parts of MAA was added to a liquid containing a polymer (chain A), and polymerization was performed at 45°C for 4 hours to form a polymer (chain B), thereby obtaining a liquid containing an AB block copolymer. The polymerization conversion calculated from the solid content is about 100%. The Mn of the AB block copolymer is 10700, the PDI is 1.31, and the acid value is 73 mgKOH / g. The peak of the A chain in GPC shifts to the high molecular weight side, confirming the formation of an AB block copolymer. Sampling and measuring the GPC results showed that the peak of the A chain shifted to the high molecular weight side, confirming that the B chain was extended from the A chain, and the molecular weight was Mn10700 and PDI was 1.31. In addition, the solid content was measured and the polymerization rate was calculated, and it was confirmed that almost all polymerization was carried out. That is, the Mn of the B chain is 5600. The acid value of the B chain calculated from the amount of MAA used is 132 mgKOH / g.

[0167] A mixture of 23.4 parts of 28% ammonia water and 118.5 parts of water was added to the liquid containing the AB block copolymer at room temperature to obtain a light brown transparent polymer solution. The obtained polymer solution was used as an aqueous solution of the pigment dispersant G-2. The pH of the obtained aqueous solution of the pigment dispersant G-2 was 9.2, and the solid content was 41.1%.

[0168] <Manufacturing of Pigment Dispersion>

[0169] (Production Example 1)

[0170] 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 Industries, Ltd.) were added to 864 parts of ion exchange water, and the mixture was stirred and mixed thoroughly with a dissolver to obtain a mixture containing a pigment and a pigment dispersant. The obtained mixture was added to a horizontal media disperser (trade name "DYNO-MILL 0.6LITRE MULTI-LAB", manufactured by Shinmaru Enterprises Corporation., diameter of zirconium oxide beads: 0.5 mm), and the dispersion treatment was performed at a peripheral speed of 7 m / s to fully disperse the pigment in the grinding base. After centrifugal separation treatment (7500 rpm, 20 minutes), coarse particles were removed by filtering with a 10 μm membrane filter. Ion exchange water was added to adjust the concentration to obtain a blue aqueous pigment dispersion B-1 with a pigment concentration of 14%.

[0171] (Production Example 2)

[0172] To 517.5 parts of ion exchange water, add 182.5 parts of an aqueous solution of a pigment dispersant G-2 (75.0 parts of a polymer) and 300 parts of CI Pigment Blue 15:3 (PB15:3, Dainichi Seika Industries, Ltd.), and stir and mix thoroughly with a dissolver to obtain a mixture containing a pigment and a pigment dispersant. The obtained mixture is added to a horizontal media disperser (trade name "DYNO-MILL0.6 LITRE MULTI-LAB", manufactured by Shinmaru Enterprises Corporation., diameter of zirconium oxide beads: 0.5 mm), and dispersed at a peripheral speed of 7 m / s to fully disperse the pigment in the grinding base. After centrifugal separation (7500 rpm, 20 minutes), filter with a 10 μm membrane filter to remove coarse particles. Add ion exchange water to adjust the concentration to obtain a blue aqueous pigment dispersion B-2 with a pigment concentration of 14%.

[0173] <Manufacturing of water-based ink>

[0174] (Example 9)

[0175] 16.0 parts of binder component E-1, 28.6 parts of pigment dispersion B-1, 18.0 parts of propylene glycol, 0.5 parts of surfactant (trade name "SILFACE SAG503A", manufactured by Nissin Chemical co., ltd.), 0.7 parts of polyethylene wax and 36.2 parts of water were mixed, stirred thoroughly, and filtered with a membrane filter with a pore size of 5 μm to obtain an aqueous ink for inkjet (ink 1).

[0176] (Examples 10 to 17, Comparative Examples 4 to 6)

[0177] Aqueous inkjet inks (inks 2 to 12) were obtained in the same manner as in Example 9 except that the binder components and pigment dispersions of the types shown in Table 3 were used.

[0178] <Evaluation>

[0179] An inkjet printer with a flat heater (trade name "MMP825H", manufactured by MASTERMIND CO., LTD.) and the printed substrate shown below were prepared. Then, using each of the prepared inks, an image was recorded on the printed substrate by an inkjet recording method to obtain a printed matter. Specifically, the printed substrate was heated to a surface temperature of 55° C. using a flat heater, and then each ink was applied to perform printing, and then dried for 10 minutes in a thermostatic bath kept at 90° C. to obtain a printed matter.

[0180] ·OPP film (polypropylene film, manufactured by FUTAMURA CHEMICAL CO., LTD., 50 μm)

[0181] PET film (polyethylene terephthalate film, manufactured by FUTAMURA CHEMICAL CO., LTD., 50 μm)

[0182] (Adhesion)

[0183] The glass ribbon was fully pressed against the image and then peeled off. The peeling of the image from the film was visually observed, and the adhesion of the image was evaluated according to the following evaluation criteria. The results are shown in Table 3.

[0184] ◎: No peeling at all.

[0185] ○: Only peeled off a little.

[0186] △: The peeled area is smaller than the non-peeled area.

[0187] ×: The peeled area is larger than the non-peeled area.

[0188] (Abrasion resistance (dry and wet abrasion resistance))

[0189] Using a Gakushin type friction fastness tester (trade name "RT-300", manufactured by Daiei Scientific Precision Manufacturing Co., Ltd.), a dry friction test was performed on the surface of the image with a load of 500 g using a dry white cloth, and a wet friction test was performed on the surface of the image with a load of 200 g using a wet white cloth. The peeling of the image after the friction test was visually observed, and the friction resistance (dry friction resistance and wet friction resistance) of the image was evaluated according to the evaluation criteria shown below. The results are shown in Table 3.

[0190] ◎: No peeling at all.

[0191] ○: Only slightly peeled off.

[0192] △: The peeled area is smaller than the non-peeled area.

[0193] ×: The peeled area is larger than the non-peeled area.

[0194] Table 3

[0195]

[0196] Industrial Applicability

[0197] By using the binder component of the present invention, it is possible to provide an environmentally friendly water-based ink that can form a dry film having excellent adhesion and abrasion resistance to polypropylene-based substrates and polyethylene-based substrates. The water-based ink is suitable for outdoor display board printing and high-speed inkjet printing, and is also useful as a water-based flexographic printing ink, a water-based coating, and a water-based writing ink.

Claims

1. A binder component for aqueous ink, which is a polymer satisfying the following characteristics (1) to (3), [Feature (1)]: is an AB block copolymer comprising a polymer chain A and a polymer chain B, wherein: The content of the structural unit derived from a biomaterial-derived methacrylate is 80% by mass or more, wherein the biomaterial-derived methacrylate is at least one selected from the group consisting of ethyl methacrylate, tetrahydrofurfuryl methacrylate, isobornyl methacrylate, dodecyl methacrylate and octadecyl methacrylate, The content of the structural unit derived from isobornyl methacrylate is 40% by mass or more, The number average molecular weight of the AB block copolymer is 10,000 to 23,000, The acid value is 25-100 mgKOH / g. The glass transition temperature is above 90°C; [Feature (2)]: The polymer chain A is the following polymer block: contains 30% by mass or more of a structural unit derived from isobornyl methacrylate, Containing 80% by mass or more of the structural unit of the methacrylate derived from a biomaterial, The number average molecular weight is 5000~18000, The glass transition temperature is above 80°C. The molecular weight distribution is below 1.6; [Feature (3)]: The polymer chain B is the following polymer block: comprising structural units derived from methacrylic acid, contains 50% by mass or more of a structural unit derived from isobornyl methacrylate, Containing 50% by mass or more of a structural unit derived from a methacrylic acid ester derived from a biomaterial, The acid value is 50~150mgKOH / g, The number average molecular weight is 3000-15000.

2. A water-based ink comprising: water, a colorant, a water-soluble organic solvent and the water-based ink binder component according to claim 1. The aqueous ink according to claim 2 , further comprising polyethylene wax.

4. The water-based ink according to claim 2 or 3, wherein: The water-soluble organic solvent comprises propylene glycol and at least one selected from the group consisting of diethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether and dipropylene glycol monomethyl ether, The content of the water-soluble organic solvent is 3 to 30% by mass. 5 . The aqueous ink according to claim 2 or 3 , which is used for printing on at least one of a polypropylene-based substrate and a polyethylene-based substrate.

Images