Ink composition and printed material

Abstract

To provide an ink composition with superior re-dispersibility, enabling the formation of a coating layer with both glue bonding suitability and adhesion to paper substrates.SOLUTION: An ink composition contains an aluminum pigment, a styrene acrylic resin, and an aqueous medium, where the styrene acrylic resin has an acid value of 160-300 mgKOH / g, and the content of the styrene acrylic resin is 12-30 mass% relative to the total solid mass of the ink composition.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to an ink composition and a printed matter. [Background technology]

[0002] Conventionally, an ink composition containing an aluminum pigment and a styrene-acrylic resin has been used.

[0003] For example, Patent Document 1 discloses an invention relating to an aqueous gravure ink containing metal pigment particles, a water-soluble organic solvent, a surfactant, and water, in which the metal pigment particles are in the form of water-insoluble polymer particles containing the metal pigment particles, the average particle size of the water-insoluble polymer particles containing the metal pigment particles in the aqueous gravure ink is 1 μm or more and 15 μm or less, the content of the metal pigment particles is 7% by mass or more and 35% by mass or less, the boiling point of the water-soluble organic solvent is 100° C. or more and 250° C. or less, and the surfactant is one or more selected from silicone-based surfactants and acetylene glycol-based surfactants. The invention relates to an aqueous gravure ink, in which the metal pigment particles can be aluminum and the water-insoluble polymer particles can be styrene-acrylic resin. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2022-053097 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, in conventional ink compositions containing aluminum pigments, the specific gravity of the aluminum pigment is larger than that of other pigments, and so there was a problem that the aluminum pigment formed a precipitate (hard caking) over time and could not be redispersed even by shaking.

[0006] Therefore, there has been a demand for an ink composition that has excellent redispersibility in addition to the performance of being able to form a coating film that has excellent adhesiveness and sizing suitability for paper substrates. [Means for solving the problem]

[0007] The present invention relates to an ink composition containing an aluminum pigment, a styrene-acrylic resin, and an aqueous medium, wherein the styrene-acrylic resin has an acid value of 160 to 300 mgKOH / g, and the content of the styrene-acrylic resin is 12 to 30 mass% in terms of solid content with respect to the total mass of the ink composition.

[0008] In the ink composition of the present invention, the styrene-acrylic resin preferably has an acid value of 170 to 250 mgKOH / g. The styrene-acrylic resin is preferably a resin neutralized with ammonia and / or an amine compound. The styrene-acrylic resin preferably has a weight average molecular weight of 12,000 to 25,000. The styrene-acrylic resin preferably has a glass transition temperature of 50° C. to 150° C. The present invention also relates to a printed matter comprising a coating film of the ink composition on a paper substrate. Effect of the Invention

[0009] The present invention can provide an ink composition capable of forming a coating film that has redispersibility, adhesiveness and suitability for gluing to paper substrates. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] <Ink composition> The present invention relates to an ink composition containing an aluminum pigment, a styrene-acrylic resin, and an aqueous medium, wherein the styrene-acrylic resin has an acid value of 160 to 300 mgKOH / g, and the content of the styrene-acrylic resin is 12 to 30 mass% in terms of solid content with respect to the total mass of the ink composition.

[0011] The ink composition of the present invention uses a styrene-acrylic resin having a specific acid value, which gives the resin good affinity for the aluminum pigment. Therefore, even if the aluminum pigment settles over time, it can be redispersed by light shaking. In addition, by setting the amount of the styrene-acrylic resin used within a specified range, the cohesiveness of the ink coating film obtained using the ink composition and its affinity for the surface of the paper substrate are improved, making it possible to form a coating film with excellent adhesiveness and sizing suitability. However, the present invention should not be construed as being limited to the above mechanism.

[0012] (aluminum pigment) The ink composition of the present invention contains an aluminum pigment.

[0013] The aluminum pigment is preferably aluminum or an aluminum alloy from the viewpoint of improving metallic gloss. When the above aluminum alloy is used, examples of metal elements or nonmetal elements that can be added other than aluminum include silver, gold, platinum, nickel, chromium, tin, zinc, indium, titanium, and copper.

[0014] The aluminum pigment may be a powder of the aluminum or aluminum alloy, or may be an aluminum paste made into a paste form with an organic solvent or the like. As the organic solvent, a known organic solvent may be appropriately selected.

[0015] The aluminum pigment may be in the form of flaky particles, granular particles, or spherical particles, but from the viewpoint of improving metallic gloss, flaky particles are preferred.

[0016] The aluminum pigment preferably has, for example, a major axis of 500 nm to 6 μm and a thickness of 15 nm to 100 nm. The major axis and thickness can be confirmed, for example, by obtaining an image of the aluminum pigment using a scanning electron microscope and measuring the major axis and thickness.

[0017] The aluminum pigment may be of the non-leafing type or the leafing type.

[0018] The content of the aluminum pigment is preferably 2 to 10% by mass based on the total mass of the ink composition.

[0019] (styrene acrylic resin) The ink composition of the present invention contains a styrene-acrylic resin.

[0020] The styrene-acrylic resin may be a polymer obtained by combining the following styrene-based monomer and acrylic-based monomer.

[0021] Examples of the styrene-based monomer include styrene, α-methylstyrene, β-methylstyrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, 2,4-dimethylstyrene, pn-butylstyrene, p-tert-butylstyrene, pn-hexylstyrene, pn-octylstyrene, pn-nonylstyrene, pn-decylstyrene, pn-dodecylstyrene, p-methoxystyrene, and p-phenylstyrene.

[0022] Examples of the acrylic monomer include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, iso-propyl (meth)acrylate, n-butyl (meth)acrylate, iso-butyl (meth)acrylate, tert-butyl (meth)acrylate, n-amyl (meth)acrylate, n-hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, n-nonyl (meth)acrylate, cyclohexyl (meth)acrylate, benzyl (meth)acrylate, dimethyl phosphate ethyl (meth)acrylate, diethyl phosphate ethyl (meth)acrylate, dibutyl phosphate ethyl (meth)acrylate, and 2-benzoyloxyethyl (meth)acrylate, (meth)acrylonitrile, 2-hydroxyethyl (meth)acrylate, (meth)acrylic acid, and maleic acid. Incidentally, (meth)acrylate means acrylate and / or methacrylate, and (meth)acrylic acid means acrylic acid and / or methacrylic acid.

[0023] The styrene-acrylic resin may contain a reaction product of maleic anhydride and a monoalcohol. Examples of the monoalcohol include methanol, ethanol, propanol, isopropanol, butanol, isobutanol, secondary butanol, pentanol, hexanol, decanol, alkyl carbitols such as ethyl carbitol, and alkyl cellosolves such as ethyl cellosolve.

[0024] The styrene-acrylic resin may contain the following monomers as necessary. Vinyl ether monomers such as vinyl methyl ether and vinyl isobutyl ether; Vinyl ketone monomers such as vinyl methyl ketone, vinyl ethyl ketone, and vinyl isopropenyl ketone; olefins such as ethylene, propylene, and butadiene

[0025] The method for preparing the polymer of the above monomer is not particularly limited, and the polymerization may be carried out by a known method. Also, known polymerization initiators, chain transfer agents, polymerization inhibitors, and the like can be used.

[0026] The above styrene-acrylic resins may be used alone or in combination of two or more kinds. It may also be in the form of an emulsion.

[0027] The styrene-acrylic resin has an acid value of 160 to 300 mgKOH / g. By having an acid value within the above range, even if sedimentation occurs in the ink composition during storage, the ink composition can be redispersed. The styrene-acrylic resin preferably has an acid value of 170 to 250 mgKOH / g, and more preferably 180 to 240 mgKOH / g. In this specification, the term "acid value" refers to a theoretical acid value calculated arithmetically from the number of milligrams of potassium hydroxide theoretically required to neutralize 1 g of the unneutralized resin. The acid value mentioned above means the value before neutralization with ammonia and / or an amine compound described below.

[0028] When two or more of the above styrene-acrylic resins are contained, from the viewpoint of favorably imparting redispersibility, it is preferable that the acid value of each of them is within the above numerical range. In other words, it is preferable that the ink composition of the present invention does not contain a resin whose acid value does not fall within the above numerical range.

[0029] The styrene-acrylic resin has a weight average molecular weight of preferably 12,000 to 25,000, and more preferably 16,000 to 20,000. By having the weight average molecular weight within the above range, even if sedimentation occurs in the ink composition during storage, the ink composition can be redispersed. In this specification, the "weight average molecular weight" refers to the weight average molecular weight measured using GPC (gel permeation chromatography) and converted into standard polystyrene.

[0030] The above styrene-acrylic resin preferably has a glass transition temperature of 50°C to 150°C, and more preferably 70°C to 150°C, from the viewpoint of various resistance properties of the ink coating film. In this specification, the "glass transition temperature" is preferably a theoretical glass transition temperature calculated by the following Wood's formula. Wood's formula: 1 / Tg=W 1 / Tg 1 +W 2 / Tg 2 +W 3 / Tg 3 +·····+W n / Tg n (In the formula, Tg is the theoretical glass transition temperature of the resin; Tg 1 ~Tg n is the glass transition temperature of each homopolymer of monomers 1, 2, 3...n that compose the resin copolymer; W 1 ~W n represents the polymerization fraction of each of the resin monomers 1, 2, 3...n. However, the glass transition temperature in Wood's equation is an absolute temperature.) The above glass transition temperature refers to the value before neutralization with a volatile basic compound or a non-volatile basic compound.

[0031] The styrene-acrylic resin is preferably a resin neutralized with ammonia and / or an amine compound. When the styrene-acrylic resin is a resin neutralized with ammonia and / or an amine compound, it is possible to favorably impart adhesiveness and adhesiveness to printed matter.

[0032] Examples of the amine compounds include triethylamine, dimethylaminoethanol, monoethanolamine, triethanolamine, tripropanolamine, aminoethylethanolamine, and diazabicyclooctane. Of these, dimethylaminoethanol is preferred from the viewpoint of favorably imparting redispersibility to the ink composition.

[0033] The method for neutralizing the styrene-acrylic resin is not particularly limited, and for example, ammonia and / or the amine compound may be added to a resin having an acid value in the above range.

[0034] The content of the styrene-acrylic resin is 12 to 30 mass % in terms of solid content relative to the total mass of the ink composition. By ensuring that the content of the styrene-acrylic resin is within the above range, it is possible to impart adhesiveness and sizing suitability to paper substrates. The content of the styrene-acrylic resin is preferably 12 to 25 mass %, and more preferably 14 to 25 mass %, in terms of solid content, relative to the total mass of the ink composition.

[0035] (aqueous medium) The ink composition of the present invention contains an aqueous medium.

[0036] Examples of the aqueous medium include water, alcohols such as methanol and ethanol, and amide compounds such as pyrrolidone. The aqueous medium may contain components other than the solid content, such as the above-mentioned resin and the wax described below.

[0037] The content of the aqueous medium is not particularly limited, but is, for example, 20 to 80% by mass relative to the total mass of the ink composition.

[0038] (wax) The ink composition of the present invention preferably contains a wax.

[0039] Examples of the wax include paraffin wax, polyethylene wax, polypropylene wax, Fischer-Tropsch wax, carnauba wax, and microcrystalline wax. The above waxes may be used alone or in combination of two or more kinds.

[0040] The wax is preferably contained in an amount of 0.1 to 5 mass % based on the total solid content of the ink composition. By including the wax in the above range, blocking resistance and slipperiness can be suitably imparted to the coating film.

[0041] (others) The ink composition of the present invention may contain a hardener, a plasticizer, a wetting agent, a water repellent, a surfactant, an adhesion aid, an antifoaming agent, an antistatic agent, a trapping agent, an antiblocking agent, a preservative, and the like. These additives can be appropriately selected from known additives.

[0042] (Method of manufacturing ink composition) The method for producing the ink composition of the present invention is not particularly limited, and the above materials may be mixed by stirring using a known method.

[0043] (Physical properties of ink composition) The ink composition of the present invention has excellent redispersibility. In this specification, the redispersibility is evaluated by the following method.

[0044] 100 g of the ink composition is filled into a 100 ml plastic container, which is then sealed and allowed to stand at 40°C for 30 days, and then cooled to 25°C. A plastic container filled with the above ink composition is gently shaken. If the precipitate is redispersed within 24 shakes, it is judged to have extremely excellent redispersibility, and if the precipitate is redispersed after 25 to 50 shakes, it is judged to have excellent redispersibility.

[0045] The ink composition of the present invention has excellent adhesiveness for coating films. In the present specification, the adhesiveness is evaluated by the following method.

[0046] The ink composition is spread on K-liner (manufactured by Oji Materia, basis weight 230 g) using a 0.10 mm mare bar to obtain a spread. SKT Glue ECO-351 (manufactured by Sakata Inx Corporation) is applied to the surface coated with the ink composition of the above-mentioned paint using a 0.30 mm mare bar, and immediately a backing paper (K ​​Liner) is adhered thereto. A 1 kg weight is placed on the adhesive surface and left to stand for 24 hours, after which the adhesive surface is peeled off and the peeled interface is visually evaluated. If the base paper of the backing paper is completely torn and adheres to the surface coated with the ink composition, it is judged to have extremely good sizing suitability, and if only part of the base paper of the backing paper is torn and adheres to the surface coated with the ink composition, it is judged to have good sizing suitability.

[0047] The ink composition of the present invention has excellent adhesion to the coating film. In the specification, adhesion is evaluated by the following method.

[0048] Obtain a drawn-down product in the same manner as for the sizing suitability described above. A cellophane tape is applied to the surface of the above-mentioned paint-bearing product on which the ink composition has been applied, and the tape is then quickly peeled off to check and evaluate the degree to which the ink composition coating peels off. If the paper surface (the surface of the K liner) is destroyed (the ink composition coating peels off at the point where the cellophane tape is applied, i.e., when the cohesive strength of the ink composition coating exceeds the cohesive strength of the paper base material), it is judged to have extremely excellent adhesion, and if only part of the paper surface (the surface of the K liner) is destroyed, it is judged to have excellent adhesion.

[0049] <Printed material> The printed matter of the present invention comprises a coating of the ink composition of the present invention on a paper substrate.

[0050] The paper base material is not particularly limited as long as it is a paper base material used for cardboard and paper bags, and for example, K-liner, white liner, coated paper, bleached and unbleached kraft paper, pure white roll paper, and high-quality paper can be used.

[0051] The method for applying the coating composition of the present invention to the paper substrate is not particularly limited, and the composition may be applied by a conventionally known general-purpose printing method such as gravure printing, flexographic printing, rotary letterpress printing, silk screen printing, offset printing, or a coating method using a conventionally known general-purpose coater such as a bar coater, a comma coater, or a spray coater. The thickness of the coating film formed is preferably in the range of, for example, 0.5 to 10 μm.

[0052] The present specification discloses the following:

[0053] The present disclosure (1) is an ink composition containing an aluminum pigment, a styrene-acrylic resin, and an aqueous medium, wherein the styrene-acrylic resin has an acid value of 160 to 300 mgKOH / g, and the content of the styrene-acrylic resin is 12 to 30 mass% in terms of solid content with respect to the total mass of the ink composition. The present disclosure (2) is the ink composition according to the present disclosure (1), in which the styrene-acrylic resin has an acid value of 170 to 250 mgKOH / g. The present disclosure (3) is the ink composition according to the present disclosure (1) or (2), in which the styrene-acrylic resin is a resin neutralized with ammonia and / or an amine compound. The present disclosure (4) is the ink composition according to any one of the present disclosures (1) to (3), wherein the styrene-acrylic resin has a weight average molecular weight of 12,000 to 25,000. The present disclosure (5) is the ink composition according to any one of the present disclosures (1) to (4), wherein the styrene-acrylic resin has a glass transition temperature of 50°C to 150°C. The present disclosure (6) is a printed matter having a coating film of the ink composition according to any one of the present disclosures (1) to (5) on a paper substrate. EXAMPLES

[0054] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. Unless otherwise specified, "%" means "% by mass" and "parts" means "parts by mass."

[0055] The materials used in the examples and comparative examples are as follows.

[0056] <Aluminum pigment> Aluminum pigment 1 (non-leafing type, solid content 66% by mass, product name "WXM7460", manufactured by Toyo Aluminum Co., Ltd.) Aluminum pigment 2 (leafing type, solid content 63% by mass, product name "Aluminum Paste WB0230", manufactured by Toyo Aluminum Co., Ltd.) <Resin> (styrene acrylic resin) Resin 1 (styrene acrylic resin, solid content 27% by mass, acid value 220 mg KOH / g, weight average molecular weight 16000, glass transition temperature 130°C, neutralized with ammonia) Resin 2 (styrene acrylic resin, solid content 20% by mass, acid value 150 mgKOH / g, weight average molecular weight 18600, glass transition temperature 100°C, neutralized with ammonia) Resin 3 (styrene acrylic resin, solid content 30% by mass, acid value 240 mgKOH / g, weight average molecular weight 16500, glass transition temperature 155°C, neutralized with ammonia) Resin 4 (styrene acrylic resin, solid content 27% by mass, acid value 170 mgKOH / g, weight average molecular weight 18000, glass transition temperature 74°C, neutralized with dimethylaminoethanol) (styrene maleic acid resin) Resin 5 (styrene-maleic acid resin, solid content 25% by mass, acid value 340 mgKOH / g, weight average molecular weight 100,000, glass transition temperature 91°C, neutralized with ammonia) <Wax> E6314 (product name "Hi-Tec E-6314", polyethylene wax emulsion, solid content 35% by mass, manufactured by Toho Chemical Industry Co., Ltd.) <Aqueous medium> methanol purified water

[0057] (Preparation of Ink Composition) The materials were mixed and stirred using a disperser in the proportions shown in Table 1 to prepare ink compositions according to the examples and comparative examples. The ink compositions thus prepared were evaluated as follows. In the evaluation criteria described below, those that did not receive an "x" rating were judged to be acceptable.

[0058] <Redispersibility> 100 g of each of the prepared ink compositions was filled into a 100 ml plastic container, which was then sealed and allowed to stand at 40°C for 30 days, and then cooled to 25°C. The plastic container filled with the ink composition was gently shaken and evaluated according to the following criteria. ○: The sediment was redispersed by shaking within 24 times. △: The sediment was redispersed by shaking 25 to 50 times. ×: The precipitate was not redispersed even after shaking 50 times.

[0059] <Suitability for gluing> The prepared ink composition was spread on K-liner (manufactured by Oji Materia, basis weight 230 g) using a 0.10 mm mare bar to obtain a spread product. SKT glue ECO-351 (manufactured by Sakata Inx Corporation) was applied to the surface coated with the ink composition of the above-mentioned paint using a 0.30 mm mare bar, and immediately a backing paper (K ​​liner) was adhered to it. A 1 kg weight was placed on the adhesive surface and left to stand for 24 hours, after which the adhesive surface was peeled off and the peeled interface was visually inspected and evaluated according to the following criteria. ◯: The base paper of the backing paper is completely torn and adheres to the surface coated with the ink composition. Δ: Part of the base paper of the backing paper is torn and adheres to the surface coated with the ink composition. ×: The adhesive peeled off at the interface, and the backing paper was not torn.

[0060] <Adhesiveness> A colored product was obtained in the same manner as in the above-mentioned paste application test. A cellophane tape was applied to the surface of the above-mentioned paint-developed product on which the ink composition had been applied, and the tape was quickly peeled off to check the degree to which the ink composition coating peeled off. The degree of peeling was evaluated according to the following criteria. ○: The paper surface (surface of the K-liner) is destroyed (the ink composition coating peels off where the cellophane tape was applied). △: Part of the paper surface (surface of the K-liner) is destroyed (part of the ink composition coating at the area where the cellophane tape was applied is peeled off). ×: The paper surface (surface of the K liner) was not destroyed, and only the coating film of the ink composition was peeled off.

[0061] [Table 1]

[0062] It was confirmed that the ink compositions of the examples were capable of forming coating films that had excellent redispersibility, and had both adhesiveness and sizing properties for paper substrates. [Industrial Applicability]

[0063] It is possible to provide an ink composition capable of forming a coating film that has excellent redispersibility and that has both adhesiveness and suitability for gluing to paper substrates.

Claims

1. An ink composition comprising an aluminum pigment, a styrene-acrylic resin, and an aqueous medium, The styrene-acrylic resin has an acid value of 160 to 300 mgKOH / g; The content of the styrene-acrylic resin is 12 to 30% by mass of solid content based on the total mass of the ink composition. Ink composition.

2. The ink composition according to claim 1, wherein the styrene-acrylic resin has an acid value of 170 to 250 mg KOH / g.

3. 3. The ink composition according to claim 1, wherein the styrene-acrylic resin is a resin neutralized with ammonia and / or an amine compound.

4. The ink composition according to claim 1 or 2, wherein the styrene-acrylic resin has a weight average molecular weight of 12,000 to 25,000.

5. The ink composition according to claim 1 or 2, wherein the styrene-acrylic resin has a glass transition temperature of 50°C to 150°C.

6. A printed matter comprising a coating of the ink composition according to claim 1 or 2 on a paper substrate.

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