Shrinkable label resin composition and printed matter

Abstract

To provide a shrinkable label resin composition which provides a coating film with superior adhesion, water resistance, abrasion resistance, hot water resistance, and whitening resistance, and to provide printed matter.SOLUTION: A shrinkable label resin composition is provided, comprising an aqueous acrylic resin emulsion containing an acrylic resin, modified starch, and an aqueous medium, where a solids ratio (mass ratio) of the acrylic resin to the modified starch in the composition is 98.5:1.5 to 60.0:40.0.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a resin composition for shrink labels and a printed matter. More specifically, the present invention relates to a resin composition for shrink labels and a printed matter in which the obtained coating film has excellent adhesiveness, water and friction resistance, hot water resistance, and non-whitening properties.

Background Art

[0002] A shrink label is a plastic film having heat shrinkability, and is a laminated film using a polyester-based film, a polystyrene-based film, a polyolefin-based film, or the like having heat shrinkability as a base film. Shrink labels are widely used as labels that are attached to containers of various products (such as PET bottle beverages, alcoholic beverages, daily necessities, pharmaceuticals, food and beverages, etc.) and display information and designs of those products.

[0003] A shrink label is attached to a container by winding a film having heat shrinkability around the container and heating it to shrink (heat-shrink) the film so that the film adheres tightly to the container. As heating methods, a steam type and a hot air type are known. When performed by the steam type, the shrink label is required to have hot water resistance (not causing blocking even when exposed to hot water such as steam).

[0004] In recent years, in order to address environmental issues, when a resin composition for shrink labels is used as a varnish composition, not only conventional solvent-based varnish compositions but also aqueous varnish compositions have been demanded. Generally, the coating film of an aqueous varnish tends to have lower hot water resistance than that of a solvent-based varnish. Therefore, when an aqueous varnish composition is used for shrink label applications, techniques have been proposed to solve the problem by adding a crosslinking agent (two-component curing) to improve hot water resistance (for example, Patent Documents 1 to 2).

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

[0006] However, the inks described in Patent Documents 1 and 2 contain a large amount of crosslinking agents to improve the heat and water resistance. Therefore, the resulting coating film has reduced flexibility and is prone to whitening after heat shrinkage. Accordingly, a resin composition for shrink labels having excellent performance in both heat and water resistance and whitening resistance has not yet been known.

[0007] The present invention has been made in view of such conventional problems, and an object thereof is to provide a resin composition for shrink labels and a printed matter in which the resulting coating film has excellent adhesiveness, water and friction resistance, heat and water resistance, and whitening resistance. [Means for Solving the Problems]

[0008] The present invention for solving the above problems mainly comprises the following configurations.

[0009] (1) An aqueous acrylic resin emulsion containing an acrylic resin, a modified starch, and an aqueous medium, wherein the solid content ratio (mass ratio) of the acrylic resin to the modified starch in the composition is 98.5:1.5 to 60.0:40.0, a resin composition for shrink labels.

[0010] According to such a configuration, the resulting coating film has excellent adhesiveness, water and friction resistance, heat and water resistance, and whitening resistance.

[0011] (2) The resin composition for shrink labels according to (1), wherein the modified starch contains at least one selected from the group consisting of oxidized starch, amphoteric starch, phosphate starch, etherified starch, acetylated starch, fatty acid esterified starch, gelatinized starch, urea-modified starch, enzyme-modified starch, acid-treated starch, maltodextrin, roasted dextrin, British gum, and grafted starch.

[0012] According to such a configuration, the resin composition for shrink labels has excellent adhesiveness, water and friction resistance, hot water resistance, and non-whitening property of the resulting coating film.

[0013] (3) The resin composition for shrink labels according to (1) or (2), further containing a crosslinking agent.

[0014] According to such a configuration, the balance between the water and friction resistance, hot water resistance, and non-whitening property of the resulting coating film is excellent.

[0015] (4) The resin composition for shrink labels according to (3), wherein the solid content of the crosslinking agent is 0.5 to 6.5% by mass in the resin composition for shrink labels.

[0016] According to such a configuration, the balance between the hot water resistance and non-whitening property of the resulting coating film is more excellent.

[0017] (5) A printed matter printed using the resin composition for shrink labels according to any one of (1) to (4).

[0018] According to such a configuration, the adhesiveness, water and friction resistance, hot water resistance, and non-whitening property of the coating film in the printed matter are excellent.

Advantages of the Invention

[0019] According to the present invention, it is possible to provide a resin composition for shrink labels and a printed matter in which the adhesiveness, water and friction resistance, hot water resistance, and non-whitening property of the resulting coating film are excellent.

Modes for Carrying Out the Invention

[0020] <Resin Composition for Shrink Labels> The resin composition for a shrink label according to an embodiment of the present invention (hereinafter also referred to as the resin composition) includes an aqueous acrylic resin emulsion containing an acrylic resin, a modified starch, and an aqueous medium. The solid content ratio (mass ratio) of the acrylic resin to the modified starch is 98.5:1.5 to 60.0:40.0. Such a resin composition for a shrink label according to the present embodiment is excellent in the adhesiveness, water and abrasion resistance, hot water resistance, and whitening property of the resulting coating film. Therefore, the resin composition for a shrink label is useful, for example, as a varnish composition capable of forming a coating film having the above characteristics. Further, the resin composition for a shrink label is useful as an ink composition capable of forming a coating film having the above characteristics by containing an appropriate pigment. Hereinafter, each will be described.

[0021] (Aqueous acrylic resin emulsion containing an acrylic resin) An aqueous acrylic resin emulsion containing an acrylic resin refers to a resin liquid in a state where the aqueous acrylic resin is emulsified and stabilized in a particulate form. The aqueous acrylic resin emulsion is not particularly limited. For example, as the aqueous acrylic resin emulsion, an ethylene / vinyl acetate / (meth)acrylic acid derivative copolymer emulsion, an ethylene / (meth)acrylic acid derivative copolymer emulsion, a poly(meth)acrylic acid derivative emulsion, a styrene / (meth)acrylic acid derivative copolymer emulsion, a vinyl acetate / (meth)acrylic acid derivative emulsion, etc. can be used. The (meth)acrylic acid derivative is an acid derivative such as acrylic acid and / or methacrylic acid, and esters thereof.

[0022] The (meth)acrylic acid derivative is acrylic acid, methacrylic acid, methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, butyl acrylate, butyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, acrylonitrile, methacrylonitrile, acrylamide, methacrylamide, etc.

[0023] When a water-based acrylic resin emulsion is incorporated, the resin composition for shrink labels exhibits excellent adhesion of the overcoat layer when used as a varnish composition. Also, when the resin composition for shrink labels is used as an ink composition, it has an excellent balance between the adhesion of the printing layer and blocking resistance.

[0024] The acid value of the resin component contained in the water-based acrylic resin emulsion is not particularly limited. For example, the acid value is preferably 10 mgKOH / g or more, more preferably 20 mgKOH / g or more. Also, the acid value is preferably 180 mgKOH / g or less, more preferably 100 mgKOH / g or less. When the acid value is within the above range, an excellent balance is achieved between the dispersibility of the emulsion in an aqueous medium and the stability of the resin composition for shrink labels. In this embodiment, the acid value is the theoretical acid value obtained arithmetically by calculating the number of mg of potassium hydroxide theoretically required to neutralize 1 g of the water-based acrylic resin emulsion based on the composition of the monomers used to synthesize the water-based acrylic resin emulsion.

[0025] The glass transition temperature (Tg) of the resin component contained in the water-based acrylic resin emulsion is preferably -30 to 150°C, more preferably -25 to 120°C. When Tg is within the above range, the resin composition for shrink labels has an excellent balance among heat resistance, adhesion, and flexibility of the overcoat layer when used as a varnish composition. Also, when the resin composition for shrink labels is used as an ink composition, it has an excellent balance among heat resistance, adhesion, and flexibility.

[0026] The method for producing the water-based acrylic resin emulsion is not particularly limited. For example, the water-based acrylic resin emulsion can be obtained by a known production method, such as a method of emulsion polymerization of a polymerizable monomer serving as a raw material for a synthetic resin in water or a water-containing solvent using a polymerization initiator in the presence of an emulsifier.

[0027] The emulsifier is not particularly limited. For example, the emulsifier is an anionic, nonionic, cationic or amphoteric surfactant, a protective colloid such as polyvinyl alcohol, or the like.

[0028] The solid content of the aqueous acrylic resin emulsion contained in the varnish composition is not particularly limited. For example, the solid content of the aqueous acrylic resin emulsion is preferably 10.0 to 40.0% by mass, more preferably 15.0 to 35.0% by mass in the varnish composition. When the solid content of the aqueous acrylic resin emulsion is within the above range, the resin composition for shrink labels has an excellent balance between the adhesiveness of the overcoat layer and the blocking resistance when used as a varnish composition. Further, when the resin composition for shrink labels is used as an ink composition, it has an excellent balance between the adhesiveness of the printed layer and the blocking resistance.

[0029] (Other aqueous resin emulsions) In the resin composition for shrink labels of the present embodiment, a part of the above-described aqueous acrylic resin emulsion may be appropriately replaced with other aqueous resin emulsions.

[0030] Other aqueous resin emulsions are not particularly limited. For example, other aqueous resin emulsions are aqueous urethane resin emulsions, aqueous acrylic urethane resin emulsions, and the like.

[0031] The aqueous urethane resin emulsion refers to a resin liquid in which an aqueous urethane resin is emulsified and stabilized in a particulate state. For example, the aqueous urethane resin emulsion is a resin emulsion such as a polyester-based urethane, a polyether-based urethane, or a polycarbonate-based urethane.

[0032] The acid value of the resin component contained in the aqueous urethane resin emulsion is not particularly limited. For example, the acid value is preferably 10 mgKOH / g or more, more preferably 20 mgKOH / g or more. Also, the acid value is preferably 60 mgKOH / g or less, more preferably 50 mgKOH / g or less. When the acid value is within the above range, the balance between the dispersibility of the emulsion in the aqueous medium and the stability of the resin composition for shrink labels is excellent.

[0033] The solid content of the aqueous urethane resin emulsion contained in the resin composition for shrink labels is not particularly limited. For example, the solid content of the aqueous urethane resin emulsion is preferably 10.0 to 40.0% by mass, more preferably 15.0 to 35.0% by mass in the resin composition for shrink labels. When the solid content of the aqueous urethane resin emulsion is within the above range, the resin composition for shrink labels has an excellent balance between the adhesiveness of the overcoat layer and the blocking resistance when used as a varnish composition. Also, the resin composition for shrink labels has an excellent balance between the adhesiveness of the printing layer and the blocking resistance when used as an ink composition.

[0034] The aqueous acrylic urethane resin emulsion refers to a resin liquid in which the aqueous acrylic urethane resin is emulsified and stabilized in a particulate state. The aqueous acrylic urethane resin is a resin containing an acrylic resin part and a urethane resin part. The resin containing an acrylic resin part and a urethane resin part may be an alternating copolymer of acrylic units and urethane units, or a urethane resin may be bonded as a side chain to the acrylic resin constituting the main chain, or an acrylic resin may be bonded as a side chain to the urethane resin constituting the main chain. For example, it can be produced with reference to the methods described in JP-A-4-103614, JP-A-10-139839, etc.

[0035] The acid value of the resin component contained in the aqueous acrylic urethane resin emulsion is not particularly limited. For example, the acid value is preferably 5 mgKOH / g or more, more preferably 25 mgKOH / g or more. Also, the acid value is preferably 100 mgKOH / g or less, more preferably 80 mgKOH / g or less. When the acid value is within the above range, the balance between the dispersibility of the emulsion in the aqueous medium and the stability of the resin composition for shrink labels is excellent.

[0036] The solid content of the aqueous acrylic urethane resin emulsion contained in the resin composition for shrink labels is not particularly limited. For example, the solid content of the aqueous acrylic urethane resin emulsion is preferably 10.0 to 40.0% by mass, more preferably 15.0 to 35.0% by mass in the resin composition for shrink labels. When the solid content of the aqueous acrylic urethane resin emulsion is within the above range, the resin composition for shrink labels has an excellent balance between the adhesiveness of the overcoat layer and the blocking resistance when used as a varnish composition. Also, the resin composition for shrink labels has an excellent balance between the adhesiveness of the printed layer and the blocking resistance when used as an ink composition.

[0037] (Modified starch) The modified starch is not particularly limited. For example, the modified starch preferably contains at least one selected from the group consisting of oxidized starch, amphoteric starch, phosphate starch, etherified starch, acetylated starch, fatty acid esterified starch, α-starch, urea-modified starch, enzyme-modified starch, acid-treated starch, maltodextrin, roasted dextrin, British gum, and grafted starch. Thereby, the resin composition for shrink labels has excellent adhesiveness, water and friction resistance, hot water resistance, and whiteness of the obtained coating film.

[0038] Oxidized starch is starch in which the sugar in the starch is ring-opened by an oxidizing agent, or the hydroxyl group in the sugar molecule is oxidized to an aldehyde group or a carboxylic acid group. The oxidized starch is not particularly limited. For example, the oxidized starch is starch obtained by treating native starch (corn starch, waxy corn starch, potato starch, tapioca starch, wheat starch, rice starch, sago palm starch, etc.) with an oxidizing agent.

[0039] The oxidizing agent is a halogen such as chlorine, bromine, hypochlorite, hypobromite, etc.

[0040] The amphoteric starch is not particularly limited. For example, the amphoteric starch is starch obtained by treating the above native starch with a compound having a cationic group and a compound having an anionic group, or a compound having both a cationic group and an anionic group.

[0041] The phosphate starch is not particularly limited. For example, the phosphate starch is phosphate starch, diphosphate starch, acetylated phosphate cross-linked starch, monoesterified phosphate cross-linked starch, phosphate cross-linked starch, etc.

[0042] The etherified starch is not particularly limited. For example, the etherified starch is allyl etherified starch, methyl etherified starch, carboxymethyl etherified starch, hydroxyethyl etherified starch, hydroxypropyl etherified starch, etc.

[0043] The acetylated starch is not particularly limited. For example, the acetylated starch is acetylated phosphate cross-linked starch, acetylated adipic acid cross-linked starch, etc.

[0044] The fatty acid esterified starch is not particularly limited. For example, it is starch that can be synthesized by a conventional method in an aqueous system or a non-aqueous solvent such as toluene, chloroform, pyridine, etc. using starch and a fatty acid or its derivative (such as acid anhydride, acid chloride, etc.).

[0045] The fatty acids used for the esterification of starch are not particularly limited. For example, the fatty acids are preferably carboxylic acids having 1 to 22 carbon atoms, more preferably carboxylic acids having 4 to 22 carbon atoms. Specifically, the fatty acids are butyric acid (C4), caproic acid (C6), caprylic acid (C8), capric acid (C 10 ), lauric acid (C 12 ), myristic acid (C 14 ), palmitic acid (C 16 ), stearic acid (C 18 ), oleic acid (C 18 ), linoleic acid (C 18 ), linolenic acid (C 18 ), eicosapentaenoic acid (C 20 ), docosahexaenoic acid (C 22 ), etc.

[0046] The pregelatinized starch is a starch obtained by instantaneously drying water-absorbed and swollen starch particles (pregelatinized starch particles) and has cold water solubility. The pregelatinized starch is not particularly limited. For example, the pregelatinized starch is a starch in which native starch having a crystal structure (β-structure) is changed to an amorphous structure (α-structure) by the collapse of the β-structure in the presence of an appropriate amount of moisture at a temperature environment of approximately 70 °C or higher.

[0047] The urea-modified starch is not particularly limited. Urea starch is a starch modified by breaking the intermolecular hydrogen bonds of starch molecules with urea and is susceptible to the action of starch-degrading enzymes.

[0048] The enzyme-modified starch is a starch obtained by hydrolyzing and dextrinizing refined starch by a high-temperature liquefaction method using enzymes such as α-amylase, β-amylase, glucoamylase, isoamylase, pullulanase, etc., and then instantaneously spray-drying. The enzyme-modified starch has a homogeneous structure, has cold water solubility, and has excellent fluidity. The enzyme-modified starch is not particularly limited. For example, the enzyme-modified starch is hydrolyzed dextrin, enzyme-decomposed dextrin, amylose, etc.

[0049] Acid-treated starch is obtained by reacting refined starch with an inorganic acid or an organic acid to hydrolyze a part of the starch molecular chain. The acid-treated starch is not particularly limited.

[0050] Maltodextrin is not particularly limited. For example, maltodextrin is a mixture of glucose monomers, dimers, oligomers, and polymers.

[0051] Roasted dextrin is obtained by adding an acid to starch and heating (roasting) it at about 110 to 200 °C to hydrolyze the starch molecular chain. The roasted dextrin is not particularly limited. For example, roasted dextrin includes white dextrin, cream dextrin, yellow dextrin, etc.

[0052] British gum, unlike roasted dextrin, is obtained by hydrolyzing the starch molecular chain only with heat without adding an acid. British gum is characterized by having a larger molecular weight than dextrin and excellent water and friction resistance. British gum is not particularly limited.

[0053] Grafted starch is obtained by bonding a synthetic polymer to unprocessed natural starch. Since grafted starch has the structures of both starch and the synthetic polymer, it has excellent compatibility with synthetic polymers such as polyvinyl alcohol and acrylic emulsion. Grafted starch is not particularly limited.

[0054] The type of functional group substituted for the hydroxyl group of the anhydroglucose residue in the modified starch is not particularly limited. For example, the functional group includes a hydroxypropyl group, an acetyl group, a carboxymethyl group, a cationic group, an acetic acid group, a phosphoric acid group, an octenyl succinic acid group, etc.

[0055] The modified starch is preferably a starch degradation product. Thereby, the resin composition for shrink labels has excellent adhesiveness, water and friction resistance, hot water resistance, and whitening property of the obtained coating film. For example, the starch degradation product is the above enzyme-modified starch, acid-treated starch, maltodextrin, roasted dextrin, British gum, etc. The degree of starch degradation in the modified starch is not particularly limited. For example, the degree of starch degradation is preferably 3 to 33, more preferably 4 to 25, and even more preferably 5 to 20. When the degree of starch degradation is within the above range, the resin composition of the present embodiment has an excellent balance between water and friction resistance and whitening property.

[0056] (aqueous medium) The aqueous medium is not particularly limited. For example, the aqueous medium is water, various water-soluble organic solvents, etc.

[0057] The water-soluble organic solvent is not particularly limited. For example, the water-soluble organic solvent is an alcohol or a polyhydric alcohol-based solvent, etc., such as methanol, ethanol, propanol, butanol, hexanol, octanol, decanol, ethylene glycol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, ethylene glycol monooctyl ether, diethylene glycol, diethylene glycol monoethyl ether, diethylene glycol monopropyl ether, diethylene glycol monobutyl ether, triethylene glycol, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, triethylene glycol monopropyl ether, triethylene glycol monobutyl ether, propylene glycol, propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, dipropylene glycol, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol monopropyl ether, dipropylene glycol monobutyl ether, tripropylene glycol, tripropylene glycol monomethyl ether, tripropylene glycol monoethyl ether, tripropylene glycol monopropyl ether, tripropylene glycol monobutyl ether, glycerin, etc.

[0058] The content of the aqueous medium is preferably 50.0% by mass or more, more preferably 60.0% by mass or more in the resin composition. Also, the content of the aqueous medium is preferably 90.0% by mass or less, more preferably 80.0% by mass or less in the resin composition. When the content of the aqueous medium is within the above range, the resin composition has an excellent balance between the washability of the printing plate and the drying property of the coating film.

[0059] The solid content ratio (mass ratio) of the acrylic resin and the modified starch may be 98.5:1.5 to 60.0:40.0, preferably 90.0:10.0 to 65.0:35.0, and more preferably 80.0:20.0 to 67.0:33.0. When the solid content ratio of the acrylic resin exceeds 98.5% by mass, the resin composition is liable to have poor whitening property. On the other hand, when the solid content ratio of the acrylic resin is less than 60% by mass, the resin composition is liable to have poor water and abrasion resistance.

[0060] (Optional component) The resin composition of the present embodiment may contain a crosslinking agent, a pigment, a leveling agent, an antifoaming agent, a wax, a viscosity modifier, a polymerization inhibitor, a solvent, an antiblocking agent, a light stabilizer, an ultraviolet absorber, an infrared absorber, a thickener (thixotropic agent), an antibacterial and antifungal agent, etc.

[0061] (Crosslinking agent) The crosslinking agent is not particularly limited. For example, the crosslinking agent is an oxazoline-based crosslinking agent, an aziridine-based crosslinking agent, an isocyanate-based crosslinking agent, an epoxy-based crosslinking agent, a melamine-based crosslinking agent, a peroxide-based crosslinking agent, a urea-based crosslinking agent, a metal alkoxide-based crosslinking agent, a metal chelate-based crosslinking agent, a metal salt-based crosslinking agent, a carbodiimide-based crosslinking agent, a hydrazine-based crosslinking agent, an amine-based crosslinking agent, a silane coupling agent, etc. Among these, the crosslinking agent is preferably at least one of an epoxy-based crosslinking agent, an aziridine-based crosslinking agent, and a metal chelate-based crosslinking agent. Thereby, a coating film having excellent heat and water resistance and water and abrasion resistance can be obtained for the resin composition.

[0062] When the crosslinking agent is blended, the content of the crosslinking agent is not particularly limited. For example, the solid content of the crosslinking agent can be appropriately determined according to the type of the crosslinking agent. For example, the solid content of the crosslinking agent is preferably 0.5% by mass or more, more preferably 1.0% by mass or more in the resin composition. Also, the solid content of the crosslinking agent is preferably 6.5% by mass or less, more preferably 6.0% by mass or less in the resin composition. When the content of the crosslinking agent is within the above range, the resin composition has an excellent balance between heat and water resistance and whitening property.

[0063] The aziridine crosslinking agent is not particularly limited. For example, the aziridine crosslinking agent may be trimethylolpropane tris[3-(1-aziridinyl)propionate], trimethylolpropane tris[3-(1-(2-methyl)aziridinylpropionate)], or the like.

[0064] When an aziridine crosslinking agent is used, the solid content of the aziridine crosslinking agent is preferably 0.5% by mass or more, more preferably 1.0% by mass or more in the resin composition. Also, the content of the aziridine crosslinking agent is preferably 4.5% by mass or less, more preferably 4.0% by mass or less in the resin composition. When the content of the aziridine crosslinking agent is within the above range, the resin composition has an excellent balance between heat and water resistance and whitening property.

[0065] The epoxy crosslinking agent is not particularly limited. For example, the epoxy crosslinking agent may be one having two or more epoxy groups in one molecule, such as N,N,N’,N’-tetraglycidyl-m-xylenediamine, 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, 1,6-hexanediol diglycidyl ether, polyethylene glycol diglycidyl ether, polyglycerol polyglycidyl ether, or the like.

[0066] When an epoxy crosslinking agent is used, the solid content of the epoxy crosslinking agent is preferably 1.0% by mass or more, more preferably 3.0% by mass or more in the resin composition. Also, the content of the epoxy crosslinking agent is preferably 6.5% by mass or less, more preferably 6.0% by mass or less in the resin composition. When the content of the epoxy crosslinking agent is within the above range, the resin composition has an excellent balance between heat and water resistance and whitening property.

[0067] The metal chelate crosslinking agent is not particularly limited. For example, the metal chelate crosslinking agent is a zirconium chelate type, a titanium chelate type, an aluminum chelate type, or the like. Among these, the metal chelate crosslinking agent is preferably a zirconium chelate crosslinking agent such as ZrOCl2, ZrO(NO3)2, K2ZrO(CO3)2, K2Zr(CO3)2(OH2)2, (NH4)2ZrO(CO3)2, (NH4)2Zr(CO3)2(OH2)2, ZrO(C2H3O2)2, Zr(C2H3O2)4, Zr(C5H7O2)4, Zr(O-n-C4H9)3(C5H7O2).

[0068] When a zirconium chelate crosslinking agent is used, the solid content of the zirconium chelate crosslinking agent is preferably 2.5% by mass or more, more preferably 3.0% by mass or more in the resin composition. Also, the content of the zirconium chelate crosslinking agent is preferably 6.5% by mass or less, more preferably 6.0% by mass or less in the resin composition. When the content of the zirconium chelate crosslinking agent is within the above range, the resin composition has an excellent balance between heat and water resistance and whitening property.

[0069] (Pigment) The pigment is preferably blended when the resin composition is an ink composition. The pigment is not particularly limited. For example, the pigment is various organic pigments and inorganic pigments. The organic pigments are dye lake pigments, azo pigments, benzimidazolone pigments, phthalocyanine pigments, quinacridone pigments, anthraquinone pigments, dioxazine pigments, indigo pigments, thioindigo pigments, perylene pigments, perinone pigments, diketopyrrolopyrrole pigments, isoindolinone pigments, nitro pigments, nitroso pigments, flavanthrone pigments, quinophthalone pigments, pyranthrone pigments, indanthrone pigments, etc.

[0070] The inorganic pigments are carbon black, titanium oxide, aluminum oxide, silica, zinc white, red iron oxide, graphite, iron black, chromium oxide green, aluminum hydroxide, etc.

[0071] The pigment may be surface-treated with a known surface treatment agent.

[0072] Yellow pigments include C.I.Pigment Yellow 1, 2, 3, 12, 13, 14, 16, 17, 42, 73, 74, 75, 81, 83, 87, 93, 95, 97, 98, 108, 109, 114, 120, 128, 129, 138, 139, 150, 151, 155, 166, 180, 184, 185, 213, etc.

[0073] Magenta pigments include C.I.Pigment Red 5, 7, 12, 22, 38, 48:1, 48:2, 48:4, 49:1, 53:1, 57, 57:1, 63:1, 101, 102, 112, 122, 123, 144, 146, 149, 168, 177, 178, 179, 180, 184, 185, 190, 202, 209, 224, 242, 254, 255, 270, C.I.Pigment Violet 19, etc.

[0074] Cyan pigments include C.I.Pigment Blue 1, 2, 3, 15, 15:1, 15:2, 15:3, 15:4, 15:6, 16, 18, 22, 27, 29, 60, etc.

[0075] Black pigments include carbon black (C.I.Pigment Black 7), etc.

[0076] White pigments include titanium oxide, aluminum oxide, etc. The white pigment may be surface-treated with various materials such as alumina and silica.

[0077] The content of the pigment is not particularly limited. For example, the content of the pigment is preferably 0.5% by mass or more, more preferably 10% by mass or more in the ink composition. Also, the content of the pigment is preferably 45% by mass or less, more preferably 40% by mass or less in the ink composition.

[0078] <Method for Preparing Resin Composition for Shrink Label> The preparation method of the resin composition for shrink labels of the present embodiment is not particularly limited. For example, the resin composition for shrink labels can be prepared by adding all the components and stirring and mixing them with a stirring device.

[0079] <Shrink film> The shrink film (shrinking plastic film) to which the resin composition for shrink labels of the present embodiment is applied is not particularly limited. For example, the shrink film is a shrinkable polypropylene film, a shrinkable polyvinyl chloride film, a shrinkable polyethylene terephthalate film, or the like.

[0080] <Printed matter and printing method of resin composition for shrink labels> The printed matter of one embodiment of the present invention is a printed matter printed using the above-described resin composition for shrink labels. The resin composition for shrink labels is printed on, for example, the above-described shrink film. The method of printing the resin composition for shrink labels on the shrink film to produce a printed matter is not particularly limited. For example, the printed matter is preferably obtained by printing the resin composition for shrink labels on the above-described shrink film, which is the object to be printed, by using a gravure printing machine or a flexographic printing machine. As the printing conditions, conventionally known conditions are appropriately employed.

[0081] A coating film of the resin composition of the above-described embodiment is formed on the printed matter. The coating film is excellent in adhesiveness to the shrink film, water and friction resistance, hot water resistance, and whitening resistance.

Examples

[0082] Hereinafter, the present invention will be described more specifically with reference to examples. The present invention is not limited to these examples. Unless otherwise specified, “%” means “mass %” and “part” means “part by mass”. The materials used in the following examples and comparative examples are as follows. The unit of the numerical values in the columns regarding each component and the total in the table is “mass %”.

[0083] The raw materials used in this example are shown below. (Acrylic resin emulsion) · Acrylic resin emulsion A Solid content 38.5% by mass, acid value 50 mg KOH / g, Tg = 0 °C <Preparation of acrylic resin emulsion A>[ An aqueous solution obtained by dissolving a copolymer composed of acrylic acid, methyl methacrylate, and styrene in aqueous ammonia was used as a polymer emulsifier. Next, to form the core part, methyl methacrylate, 2-ethylhexyl acrylate, and diacetone acrylamide were added and emulsion polymerization was carried out by a conventional method. Thereafter, 1% by mass of adipic acid dihydrazide (ADH) was added to the obtained acrylic resin emulsion solution to prepare an acrylic resin emulsion liquid (acrylic resin emulsion A). (Starch, polysaccharide) · Enzyme-modified starch PENCOTE D MV: Manufactured by Ingredion, enzyme-modified waxy corn starch, solid content 100% by mass · Maltodextrin M-3: Manufactured by Ingredion, solid content 100% by mass (Crosslinking agent) Denacol EX-614B: Epoxy-based crosslinking agent, manufactured by Nagase ChemteX Corporation, solid content 100% by mass SU-125F: Aziridine-based crosslinking agent, manufactured by Meisei Chemical Industry Co., Ltd., solid content 20% by mass (Others) Surfynol 104E: Leveling agent, manufactured by Nissin Chemical Industry Co., Ltd., solid content 50% by mass TEGO Foamex825: Antifoaming agent, manufactured by EVONIK, solid content 20% by mass ChemPearl W-401: Wax, manufactured by Mitsui Chemicals, Inc., solid content 40% by mass SN Thickener 601: Viscosity modifier, manufactured by San Nopco Ltd., solid content 40% by mass

[0084] <Examples 1 to 11, Comparative Examples 1 to 4> (Preparation of resin composition for shrink label) According to the formulations shown in Table 1, each material was stirred and mixed to prepare each resin composition for shrink label.

[0085]

Table 1

[0086] Using the obtained resin composition for shrink labels, printed matter samples were prepared and the following evaluations were conducted. The results are shown in Table 1.

[0087] <Preparation of Printed Matter Samples> Each resin composition for shrink labels was applied to a shrinkable PET film (manufactured by Toyobo Co., Ltd., SP809 #40μm) at a Wet coating amount of 4.0 g / m 2 using a proof coater, dried with hot air for several seconds, and then dried at room temperature overnight to prepare printed matter samples.

[0088] <Adhesion> A cellophane tape was attached to the overcoat layer (varnish surface) of the printed matter sample and rapidly peeled off. The adhesion was evaluated according to the following evaluation criteria based on the degree of peeling of the overcoat layer. Samples with evaluation results of ○ or △ were considered to pass. (Evaluation Criteria) ○: The peeling ratio of the overcoat layer from the base film was less than 5% in terms of area ratio. △: The peeling ratio of the overcoat layer from the base film was 5% or more and less than 30% in terms of area ratio. ×: The peeling ratio of the overcoat layer from the base film was 30% or more in terms of area ratio. <Water and Rub Resistance> Using a Kanakin No. 3 dipped in water as a friction element on the printed surface, a 100 - cycle reciprocating motion was performed at a load of 200 g using a Gakushin - type testing machine (manufactured by Daiei Scientific Instruments Co., Ltd.), and the water and rub resistance was evaluated based on the degree of ink dropout. Samples with evaluation results of ○ or △ were considered to pass. (Evaluation Criteria) ○: There was no dropout of the overcoat layer. △: The dropout of the overcoat layer was less than 50% in terms of area ratio. ×: The dropout of the overcoat layer was 50% or more in terms of area ratio. <Hot water resistance> The printed sample was wrapped around a commercially available PET bottle (500 ml square bottle) so that the printed surface became the outer surface, and the printed sample was shrunk by exposing it to hot water at 90 °C, and then attached to the bottle. After filling the PET bottle with the printed sample with hot water at 90 °C and covering it, the PET bottles wet with water were stacked horizontally in a state where they were in close contact with each other. After natural cooling for 30 minutes in that state, the water in the contents was removed and dried in an oven at 40 °C. After drying, the hot water resistance was evaluated based on the presence or absence of blocking of the printed matter. Those with an evaluation result of ○ or △ were considered qualified. (Evaluation criteria) ○: No blocking was confirmed at all. △: Blocking was partially confirmed. ×: Considerable blocking was observed. <Whitening property> Both ends of the printed sample were fixed to a stainless steel plate, immersed in hot water at 90 °C for 20 seconds, and shrunk and dried. The haze value of the printed matter shrunk by 50% was measured using a haze meter, and the whitening property was evaluated. Those with an evaluation result of ○ or △ were considered qualified. (Evaluation criteria) ○: The haze value was less than 50. △: The haze value was 50 or more and less than 70. ×: The haze value was 70 or more.

[0089] As shown in Table 1, the coating films obtained using the resin compositions for shrink labels of Examples 1 to 11 of the present invention exhibited excellent adhesiveness, water and abrasion resistance, hot water resistance, and whitening property.

Claims

1. An aqueous acrylic resin emulsion containing an acrylic resin, a modified starch, and an aqueous medium, wherein the solid content ratio (mass ratio) of the acrylic resin to the modified starch in the composition is 98.5:1.5 to 60.0:40.0, a resin composition for shrink labels.

2. The resin composition for shrink labels according to claim 1, wherein the modified starch contains at least one selected from the group consisting of oxidized starch, amphoteric starch, phosphate starch, etherified starch, acetylated starch, fatty acid esterified starch, α-starch, urea-modified starch, enzyme-modified starch, acid-treated starch, maltodextrin, roasted dextrin, British gum, and grafted starch.

3. The resin composition for shrink labels according to claim 1 or 2, further comprising a crosslinking agent.

4. The resin composition for shrink labels according to claim 3, wherein the solid content of the crosslinking agent is 0.5 to 6.5% by mass in the resin composition for shrink labels.

5. A printed matter printed using the resin composition for shrink labels according to claim 1 or 2.

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