Water-based varnish composition, laminate and packaging material

Abstract

To provide an aqueous varnish composition for gravure printing or flexographic printing, which is excellent in adhesion to polyolefin films, acid resistance, and blocking resistance, can form a coating film having abrasion resistance that can withstand friction with rubber, and has excellent storage stability, and to provide a laminate and a packaging material using the same. [Solution] An aqueous varnish composition for gravure printing or flexographic printing, containing a (meth)acrylic resin emulsion (A), a modified polypropylene resin emulsion (B), and an aqueous medium (C), wherein the acid value of (A) is 60 mgKOH / g or less, the average particle size is 0.038 to 0.300 μm, the acid value of (B) is 60 mgKOH / g or less, the difference between the acid values ​​of (A) and (B) satisfies a specific relationship, the content of (B) converted to solids is 1.6 to 15.0 mass%, and the mass ratio, converted to solids, represented by (B) / (A) is 0.020 to 0.180.

Description

[Technical Field]

[0001] The present invention relates to an aqueous varnish composition, a laminate, and a packaging material. [Background technology]

[0002] Flexible packaging materials such as plastic films used for packaging food, daily necessities, etc. are printed with inks and varnishes by gravure printing or flexographic printing for the purposes of displaying information, adding design, functionality, etc. In the past, oil-based inks and varnishes using organic solvents were the mainstream for flexible packaging, but in recent years, there has been a growing demand for water-based inks and varnishes from the perspective of environmental issues, etc.

[0003] One application of flexible packaging materials is packaging labels that are attached to containers such as plastic containers, metal containers, paper containers, etc. Examples of packaging labels include roll labels that are attached by wrapping them around the container and fastening them with adhesive, and shrink labels that are attached by applying heat and shrinking them to fit the shape of the container. A typical configuration of the packaging label is one in which an ink layer serving as a design layer is laminated on the inside of a plastic film, i.e., on the container side, and a varnish layer is laminated on the surface of the ink layer to protect the ink layer from contact with the container, etc. Another typical example of such a configuration is one in which a varnish layer is further laminated on the outside of the plastic film, i.e., on the side opposite the container, to protect the plastic film from external contact, such as human hands. In recent years, a matte ink layer has been used as the outer varnish layer, not only for the purpose of protecting the plastic film from external contact, but also for improving design. The varnish layer, ink layer, and matte ink layer are coatings formed by printing using varnish, ink, and matte ink, respectively. Hereinafter, these will be collectively referred to as printed coatings or printed layers.

[0004] Plastic films used in packaging labels using water-based varnishes include polyethylene terephthalate film (PET film), nylon film (NY film), and polystyrene film (PS film). In recent years, polyolefin films (PO film) such as polypropylene film (PP film) have been increasingly used for a variety of reasons, including higher oxygen permeability, lower moisture permeability, lower specific gravity, flexibility, and lower cost. However, PO film has lower wetting tension and a lower solubility parameter than other films, posing a challenge when using water-based varnishes, resulting in poor adhesion between the PO film and the varnish layer.

[0005] However, since the environment in which packaging labels are used and the contents contained in containers are often acidic, there are many situations in which the printed coating film is exposed to acidic substances. Furthermore, the printed coating film is required to be able to withstand friction under severe conditions, such as the risk of the printed coating film peeling off due to friction with the rubber roll installed in the printing press. In addition, when the printed material is wound up after printing, it is also required to prevent the printed coating film from transferring to the opposite side that comes into contact with the printed coating film, resulting in poor appearance and poor processing. Therefore, the printed coating film of the packaging label is required to have coating film physical properties such as acid resistance, blocking resistance, abrasion resistance, etc. In particular, in the case of gravure printing or flexographic printing, the printing distance at one time is longer than in inkjet printing, and therefore the amount of printed matter taken up is also larger, and pressure is easily applied to the printed matter, which makes it easy for the printed coating film to transfer to the opposite surface that comes into contact with the printed coating film, and therefore excellent blocking resistance is required.

[0006] Furthermore, in order to improve the physical properties of the coating, aqueous varnishes often use core-shell resins with a low hydrophilic resin in the core, which can lead to problems such as thickening and gelation due to the collapse of the core-shell structure in the aqueous varnish depending on the usage and storage environments. For this reason, aqueous varnishes are required to have excellent storage stability.

[0007] In order to improve adhesion to polypropylene film, studies have been conducted to date on the inclusion of a modified polypropylene resin emulsion in an aqueous varnish, which has a solubility parameter close to that of polypropylene film and has affinity for it. For example, Patent Document 1 discloses an aqueous binder containing aqueous polyurethane, a modified polypropylene-based resin emulsion, and an aqueous acrylic resin. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Application Laid-Open No. 2002-226758 Summary of the Invention [Problem to be solved by the invention]

[0009] However, the aqueous binder described in Patent Document 1 is intended for use in lamination. The printed coating film protected by lamination is rarely required to have good coating film properties, and does not satisfy acid resistance, abrasion resistance with rubber, etc. Furthermore, the storage stability is also insufficient, and there is room for improvement in adhesion to PO film and blocking resistance.

[0010] The present invention addresses the need to provide an aqueous varnish composition for gravure printing or flexographic printing that is capable of forming a coating film that has excellent adhesion to polyolefin films, acid resistance, and blocking resistance, and that has abrasion resistance that can withstand friction with rubber, and that also has excellent storage stability, as well as a laminate and packaging material that use the same. [Means for solving the problem]

[0011] The present invention has the following aspects. [1] An aqueous varnish composition for gravure printing or flexographic printing, comprising a (meth)acrylic resin emulsion (A), a modified polypropylene resin emulsion (B), and an aqueous medium (C), the (meth)acrylic resin emulsion (A) has an acid value of 60 mgKOH / g or less and an average particle size of 0.038 to 0.300 μm; the acid value of the modified polypropylene resin emulsion (B) is 60 mgKOH / g or less; a difference between the acid value of the (meth)acrylic resin emulsion (A) and the acid value of the modified polypropylene resin emulsion (B) satisfies the following formula (1) or (2): the content of the modified polypropylene resin emulsion (B) in terms of solid content is 1.6 to 15.0 mass% based on the total solid content of the aqueous varnish composition; An aqueous varnish composition, wherein the mass ratio of the modified polypropylene resin emulsion (B) to the (meth)acrylic resin emulsion (A) is 0.020 to 0.180 in terms of solid content. When the acid value of the (meth)acrylic resin emulsion (A) is equal to or greater than the acid value of the modified polypropylene resin emulsion (B): Acid value of (meth)acrylic resin emulsion (A) - Acid value of modified polypropylene resin emulsion (B) ≦ 52 (1) In the case of (meth)acrylic resin emulsion (A) acid value < modified polypropylene resin emulsion (B): Acid value of modified polypropylene resin emulsion (B) - Acid value of (meth)acrylic resin emulsion (A) ≦ 30 (2) [2] The aqueous varnish composition according to [1] above, wherein the (meth)acrylic resin emulsion (A) has a minimum film-forming temperature of 50°C or lower. [3] Further containing a hydrocarbon wax (D), The aqueous varnish composition according to [1] or [2] above, wherein the hydrocarbon wax (D) has a penetration of 12 or less and an average particle size of 6 μm or less. [4] Further containing a thickener (E), The aqueous varnish composition according to any one of the above [1] to [3], wherein the thickener (E) is a polyurethane associative thickener. [5] Further containing a curing agent (F), The aqueous varnish composition according to any one of [1] to [4] above, wherein the curing agent (F) is an aziridine-based curing agent. [6] A laminate comprising a plastic film and a varnish layer formed on one side of the plastic film using the aqueous varnish composition described in any one of [1] to [5]. [7] The laminate described in [6], further comprising a pattern layer between the plastic film and the varnish layer. [8] A packaging material comprising the laminate according to [6] or [7]. [Effects of the Invention]

[0012] The present invention provides an aqueous varnish composition for gravure printing or flexographic printing that has excellent adhesion to polyolefin films, acid resistance, and blocking resistance, and is capable of forming a coating film that has abrasion resistance that can withstand friction with rubber, and that also has excellent storage stability, as well as a laminate and packaging material that use the same. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a cross-sectional view schematically illustrating an example of a laminate of the present invention. [Figure 2] FIG. 2 is a cross-sectional view schematically showing another example of the laminate of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0014] The present invention will be described in detail below. The following embodiments are merely examples for explaining the present invention, and are not intended to limit the present invention to these embodiments. The present invention can be implemented in various forms without departing from the spirit of the present invention. In the present invention, the term "aqueous" in the context of an aqueous varnish composition means that the medium contains water. The proportion of water in the medium of the aqueous varnish composition is preferably 50% by mass or more, more preferably 70% by mass or more, and particularly preferably 90% by mass or more, relative to the total mass of the medium, and may even be 100% by mass. A "coating film" refers to a coating film formed by an aqueous varnish composition. In particular, a coating film before drying is also called a "coating film," and a coating film after drying is also called a "varnish layer." A coating film is obtained by applying the aqueous varnish composition of the present invention to a surface to be coated with the aqueous varnish composition of the present invention (e.g., a plastic film, etc.). A varnish layer is obtained by drying the coating film and removing volatile components such as the medium in the coating film. The term "medium" refers to volatile components such as water, organic solvents, etc. Specifically, it refers to the components (volatile components) other than the following solid components. The "solids" of an aqueous varnish composition refers to the components (non-volatile components) contained in the aqueous varnish composition excluding the medium, and are the components that will ultimately form the varnish layer. Even if components other than the medium are liquid at room temperature, they are not included in the medium, but are included in the solids. The solids content is measured in accordance with JIS K 5601-1-2:2008. The "total solid content" of an aqueous varnish composition means the total mass (total amount) of solids contained in the aqueous varnish composition. The contents of all components other than the medium in the aqueous varnish composition are calculated as solid contents. The term "unit" refers collectively to an atomic group derived from one molecule of the monomer formed directly by polymerization of the monomer, and an atomic group obtained by chemically converting a portion of the atomic group. Note that a "structural unit based on a monomer" may also be simply referred to as a "monomer unit." For example, a "structural unit based on propylene" may also be referred to as a "propylene unit." "(Meth)acrylic" is a general term for "acrylic" and "methacrylic." "Aqueous binder resin" is a general term for "water-soluble binder resin" and "water-dispersible binder resin." Examples of water-dispersible binder resins include emulsion-type and dispersion-type. The medium of the aqueous binder resin is considered to be included in the medium of the aqueous varnish composition. The symbol "to" indicating a range of values ​​means that the values ​​before and after it are included as the lower and upper limits. For example, A to B is equivalent to A or more and B or less. The lower and upper limits of the ranges disclosed in this specification can be combined in any way to create new ranges.

[0015] The weight average molecular weights of the (meth)acrylic resin emulsion (A) and the modified polypropylene resin emulsion (B) are each weight average molecular weights converted into standard polystyrene molecular weights, and are measured by gel permeation chromatography (GPC). The glass transition temperature of the (meth)acrylic resin emulsion (A) is measured as follows in accordance with JIS K 7121:2012: That is, using a differential scanning calorimeter, 10 mg of the (meth)acrylic resin emulsion (A) is heated from −100° C. to 160° C. at a rate of 20° C. / min to obtain a curve (DSC curve), and the glass transition temperature is determined from the intersection of the baseline and the tangent to the endothermic curve. The acid values ​​of the (meth)acrylic resin emulsion (A) and the modified polypropylene resin emulsion (B) are the amount of potassium hydroxide required to neutralize acid groups such as carboxyl groups per gram of nonvolatile matter of the sample, expressed in milligrams, and are measured in accordance with JIS K 5601-2-1:1999. The average particle size of the (meth)acrylic resin emulsion (A) and the modified polypropylene resin emulsion (B) is the particle size at a volume-based cumulative frequency of 50% (median size: D50) calculated from the particle size distribution measured by dynamic light scattering. The minimum film-forming temperature of the (meth)acrylic resin emulsion (A) is measured in accordance with JIS K 6828-2:2003. The average particle size of hydrocarbon wax (D) is the particle size at 50% cumulative frequency (median size: D50) calculated from the particle size distribution measured by the Coulter counter method. The Coulter counter method is a method for electrically measuring particle size and particle size distribution of particles by passing particles dispersed in a medium through a fine hole and observing the change in the electrical signal when the particles pass through. The penetration of the hydrocarbon wax (D) is determined in accordance with JIS K 2235: 2022. The measurement temperature is 25°C.

[0016] [Water-based varnish composition] The aqueous varnish composition of this embodiment contains a (meth)acrylic resin emulsion (A), a modified polypropylene resin emulsion (B), and an aqueous medium (C). The aqueous varnish composition may further contain a hydrocarbon wax (D). The aqueous varnish composition may further contain a thickener (E). The aqueous varnish composition may further contain a curing agent (F). The aqueous varnish composition may further contain other components (hereinafter also referred to as "other optional components") other than the (meth)acrylic resin emulsion (A), the modified polypropylene resin emulsion (B), the aqueous medium (C), the hydrocarbon wax (D), the thickener (E), and the curing agent (F), as necessary, within a range that does not impair the effects of the present invention.

[0017] <(Meth)acrylic resin emulsion (A)> The (meth)acrylic resin emulsion (A) (hereinafter also referred to as "resin (A)") is an emulsion-type (meth)acrylic resin, and is a type of water-dispersible binder resin, specifically, a type of water-dispersible (meth)acrylic resin. Resin (A) typically has a core-shell structure. The core portion of the core-shell structure is preferably a hydrophobic (meth)acrylic resin. The shell portion of the core-shell structure is preferably a hydrophilic (meth)acrylic resin. The core portion and shell portion may be bonded by a crosslinking agent.

[0018] The hydrophobic (meth)acrylic resin of the core portion is typically a resin containing a structural unit based on a (meth)acrylate monomer. Examples of such resins include a homopolymer of a (meth)acrylate monomer, a copolymer of two or more (meth)acrylate monomers, and a copolymer of a (meth)acrylate monomer and a monomer other than a (meth)acrylate monomer. The (meth)acrylate monomer is preferably one that does not have a carboxyl group.

[0019] The hydrophilic (meth)acrylic resin of the shell portion is typically a resin containing a structural unit based on a carboxyl group-containing monomer. Examples of such resins include a homopolymer of a carboxyl group-containing monomer, a copolymer of two or more carboxyl group-containing monomers, and a copolymer of a carboxyl group-containing monomer and a monomer other than the carboxyl group-containing monomer. The monomer other than the carboxyl group-containing monomer may be any monomer that does not have a carboxyl group, and may be either a (meth)acrylate monomer or a monomer other than a (meth)acrylate-based monomer.

[0020] Examples of the (meth)acrylate monomer include alkyl (meth)acrylates such as methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, isobutyl (meth)acrylate, n-hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and lauryl (meth)acrylate; cycloalkyl (meth)acrylates such as cyclohexyl (meth)acrylate; aryl (meth)acrylates such as phenyl (meth)acrylate; aralkyl (meth)acrylates such as benzyl (meth)acrylate; and hydroxyalkyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate. The (meth)acrylate monomers may be used alone or in combination of two or more.

[0021] Examples of the carboxyl group-containing monomer include (meth)acrylic acid, maleic acid (maleic anhydride), fumaric acid, and itaconic acid (itaconic anhydride). The carboxyl group-containing monomers may be used alone or in combination of two or more.

[0022] Examples of monomers other than (meth)acrylate monomers and carboxyl group-containing monomers include conjugated diene compounds such as 1,3-butadiene, isoprene, and chloroprene; aromatic vinyl compounds such as styrene, α-methylstyrene, halogenated styrene, and divinylbenzene; vinyl cyanide compounds such as acrylonitrile and methacrylonitrile; acrylamides such as N,N-dimethyl(meth)acrylamide and N,N-diethyl(meth)acrylamide; and unsaturated carboxylic acid esters such as diethyl maleate, dibutyl maleate, dibutyl fumarate, diethyl itaconate, and dibutyl itaconate. These monomers may be used alone or in combination of two or more.

[0023] The resin (A) may be a self-crosslinking type. When the resin (A) is a self-crosslinking type, the resin (A) typically contains a structural unit based on a monomer containing a reactive functional group. The structural unit based on a monomer containing a reactive functional group may be contained in the core portion, the shell portion, or both. Examples of the reactive functional group-containing monomer include alkoxysilyl group-containing monomers, hydrazine group-containing monomers, epoxy group-containing monomers, methylol group-containing monomers, alkoxymethyl group-containing monomers, adipic acid dihydrazide, diacetone acrylamide, vinyl acetoacetate, allyl acetoacetate, and acetoacetoxyalkyl (meth)acrylates. Examples of epoxy group-containing monomers include glycidyl (meth)acrylate, 2,3-epoxycyclohexyl (meth)acrylate, 3,4-epoxycyclohexyl (meth)acrylate, and allyl glycidyl ether. Examples of acetoacetoxyalkyl (meth)acrylates include acetoacetoxyethyl (meth)acrylate, acetoacetoxypropyl (meth)acrylate, acetoacetoxybutyl (meth)acrylate, and 2,3-di(acetoacetoxy)propyl (meth)acrylate. The reactive functional group-containing monomers may be used alone or in combination of two or more.

[0024] In the resin (A), the mass ratio of the core portion to the shell portion (core portion:shell portion) is preferably 20:80 to 80:20, more preferably 25:75 to 75:25, and even more preferably 30:70 to 70:30. When the mass ratio of the core portion to the shell portion is within the above range, the aqueous varnish composition will have excellent storage stability, film-forming properties, adhesion of the coating film to the substrate, blocking resistance, abrasion resistance, and water-rubbing resistance. If the core portion is more and the shell portion is less than the above range, the storage stability, film-forming properties, and adhesion of the coating film to the substrate of the aqueous varnish composition will be slightly reduced. If the core portion is less and the shell portion is more than the above range, the blocking resistance, abrasion resistance, and water-rubbing resistance of the coating film will be slightly reduced.

[0025] The acid value of resin (A) (hereinafter also referred to as "acid value of (A)") is 60 mgKOH / g or less, preferably 55 mgKOH / g or less, and more preferably 50 mgKOH / g or less, and may be 0 mgKOH / g or more, 1 mgKOH / g or more, 5 mgKOH / g or more, 10 mgKOH / g or more, 20 mgKOH / g or more, or 25 mgKOH / g or more. The above upper and lower limits can be combined as appropriate. If the acid value of (A) exceeds the above upper limit, the adhesion of the coating film to the substrate, acid resistance, water abrasion resistance, and storage stability will decrease.

[0026] The average particle size of resin (A) is 0.038 to 0.300 μm, preferably 0.039 to 0.250 μm, and more preferably 0.040 to 0.200 μm. If the average particle size of resin (A) is less than the above lower limit, the adhesion of the coating film to the substrate, acid resistance, blocking resistance, and water friction resistance will decrease. If the average particle size of resin (A) exceeds the above upper limit, the adhesion of the coating film to the substrate, friction resistance (particularly, friction resistance against rubber (hereinafter also referred to as "rubber friction resistance")), film-forming ability, and dispersion stability will decrease.

[0027] The glass transition temperature of resin (A) is preferably -10 to 90°C, more preferably -5 to 70°C, and even more preferably 0 to 60°C. If the glass transition temperature of resin (A) is below the above lower limit, the water rub resistance and blocking resistance of the coating film will be slightly reduced. If the glass transition temperature of resin (A) exceeds the above upper limit, the adhesion of the coating film to the substrate and rub resistance (particularly rubber rub resistance) will be slightly reduced.

[0028] The minimum film-forming temperature of resin (A) is preferably not more than 70° C., more preferably not more than 50° C., even more preferably not more than 30° C., and particularly preferably not more than 10° C. If the minimum film-forming temperature of resin (A) exceeds the above upper limit, the film-forming properties of the aqueous varnish composition, the adhesion of the coating film to the substrate, acid resistance, abrasion resistance, and water abrasion resistance will be slightly reduced.

[0029] The weight-average molecular weight of resin (A) is preferably 30,000 to 1,000,000, more preferably 50,000 to 900,000, and even more preferably 100,000 to 800,000. If the weight-average molecular weight of resin (A) is less than the above-mentioned lower limit, the abrasion resistance (particularly abrasion resistance against fabric (hereinafter also referred to as "fabric abrasion resistance") and rubber abrasion resistance), water abrasion resistance, and blocking resistance of the coating film will be slightly reduced. If the weight-average molecular weight of resin (A) exceeds the above-mentioned upper limit, the storage stability of the aqueous varnish composition will be slightly reduced.

[0030] The resin (A) may be one produced by a known production method, or a commercially available product. In producing resin (A), the method of polymerizing the monomers is not particularly limited, but examples include radical polymerization, anionic polymerization, and cationic polymerization. Particularly, examples of radical polymerization include bulk polymerization, solution polymerization, emulsion polymerization, and suspension polymerization. Among these, emulsion polymerization is preferred. Emulsion polymerization is a method in which the monomers used for polymerization are polymerized in an aqueous medium in the presence of an emulsifier and a polymerization initiator. Resin (A) may be produced by separately producing a core portion and a shell portion and then combining them, or by multi-stage emulsion polymerization. The polymerization method may be any of random copolymerization, block copolymerization, graft copolymerization, and the like.

[0031] Commercially available resins (A) include, for example, the "Hiros-X" series manufactured by CHEMIPAZ Corporation; the "Joncryl" series manufactured by BASF Japan Ltd.; and the "Neocryl" series manufactured by Covestro. The resin (A) may be used alone or in combination of two or more kinds.

[0032] <Modified polypropylene resin emulsion (B)> The modified polypropylene resin emulsion (B) (hereinafter also referred to as "resin (B)") is an emulsion-type modified polypropylene resin, and is typically a resin that is obtained by modifying a polypropylene resin to introduce functional groups, and then stabilizing the resin as an emulsion in water by using an emulsifier or by self-emulsifying or by forming a core-shell structure. Resin (B) is a water-dispersible binder resin, specifically a type of water-dispersible modified polypropylene resin. Resin (B) is typically a resin containing propylene units and monomer units having a modifying group. Resin (B) may contain units of olefins other than propylene units (hereinafter also referred to as "other olefins").

[0033] Examples of other olefins include ethylene, 1-butene, isobutene, 1-pentene, 1-hexene, 1-octene, norbornene, 4-methyl-1-pentene, and 3-methyl-1-pentene. The other olefins may be used alone or in combination of two or more.

[0034] The content of the other olefin units is preferably 50% by mass or less, more preferably 40% by mass or less, and even more preferably 30% by mass or less, when the total content of the propylene units and the other olefin units is 100% by mass. In this specification, "substantially free" means that it is not intentionally added.

[0035] The modifying group is not particularly limited, but an acid-modified group is preferred from the viewpoint of the storage stability of the aqueous varnish composition and the adhesion of the coating film to the substrate (particularly adhesion to polyolefin films (hereinafter also referred to as "PO films") such as polypropylene films (hereinafter also referred to as "PP films"). In other words, the monomer having an acid-modified group is preferred as the modifying group, and the resin (B) is preferably an acid-modified polypropylene resin emulsion. Examples of the acid-modified group include a carboxy group, an acid anhydride group, a sulfonic acid group, etc. Among these, a carboxy group and an acid anhydride group are preferred.

[0036] Examples of monomers having an acid-modified group include unsaturated carboxylic acids. Examples of unsaturated carboxylic acids include acrylic acid, methacrylic acid, maleic acid, maleic anhydride, itaconic acid, itaconic anhydride, aconitic acid, aconitic anhydride, fumaric acid, crotonic acid, citraconic acid, mesaconic acid, allylsuccinic acid, half esters and half amides of unsaturated dicarboxylic acids, ethylenesulfonic acid, allylsulfonic acid, methallylsulfonic acid, etc. Among these, from the viewpoint of reactivity during copolymerization, maleic anhydride, acrylic acid, and methacrylic acid are preferred, and maleic anhydride is more preferred. The unsaturated carboxylic acids may be used alone or in combination of two or more.

[0037] The content of the monomer unit having a modifying group is preferably 0.1 to 15 parts by mass, more preferably 1 to 10 parts by mass, and even more preferably 1.5 to 7 parts by mass, per 100 parts by mass of the total content of the propylene unit and the other olefin unit. If the content of the monomer unit having a modifying group is less than the above lower limit, it becomes difficult to emulsify the modified polypropylene resin. In addition, the adhesion of the coating film to the substrate (particularly, adhesion to PP film) is slightly reduced. If the content of the monomer unit having a modifying group exceeds the above upper limit, the blocking resistance of the coating film is slightly reduced.

[0038] Resin (B) may further contain units of monomers other than propylene units, other olefin units, and monomer units having a modifying group (hereinafter also referred to as "other monomers"), as necessary, within a range that does not impair the effects of the present invention. The other monomer is not particularly limited as long as it is copolymerizable with ethylene.

[0039] The acid value of resin (B) (hereinafter also referred to as "acid value of (B)") is 60 mgKOH / g or less, preferably 55 mgKOH / g or less, more preferably 40 mgKOH / g or less, and may be 0 mgKOH / g or more, 5 mgKOH / g or more, 10 mgKOH / g or more, or 15 mgKOH / g or more. The above upper and lower limits can be combined as appropriate. If the acid value of (B) exceeds the above upper limit, the adhesion of the coating film to the substrate (particularly adhesion to PP film), acid resistance, and water friction resistance will decrease.

[0040] The difference between the acid value of (A) and the acid value of (B) satisfies the following formula (1) or (2). If the acid value of (A) is greater than or equal to the acid value of (B): Acid value of (A) - Acid value of (B) ≦ 52 (1) If the acid value of (A) is less than the acid value of (B): Acid value of (B) - Acid value of (A) ≦ 30 (2)

[0041] The acid value of (A) minus the acid value of (B) (hereinafter also referred to as the "acid value difference (AB)") is 52 or less, preferably 50 or less, more preferably 45 or less, even more preferably 40 or less, even more preferably 35 or less, particularly preferably 30 or less, and most preferably 25 or less, and may be 0 or more, 1 or more, 3 or more, 5 or more, or 10 or more. The above upper and lower limits can be appropriately combined. If the acid value difference (AB) exceeds the above upper limit, the stabilized state of the resin (A) and resin (B) emulsion in the aqueous varnish composition is likely to be disrupted, gelation and thickening are likely to occur, and the storage stability of the aqueous varnish composition is reduced. In addition, the adhesion of the coating film to the substrate and the water-rub resistance are reduced.

[0042] The acid value of (B) minus the acid value of (A) (hereinafter also referred to as the "acid value difference (BA)") is 30 or less, preferably 28 or less, more preferably 25 or less, even more preferably 23 or less, and even more preferably 20 or less. It may also be greater than 0, 1 or more, 3 or more, 5 or more, or 10 or more. The above upper and lower limits can be combined as appropriate. If the acid value difference (BA) exceeds the above upper limit, the stabilized state of the emulsion of resins (A) and (B) in the aqueous varnish composition is likely to be disrupted, gelation and thickening are likely to occur, and the storage stability of the aqueous varnish composition is reduced. Additionally, the adhesion of the coating film to the substrate, blocking resistance, and water abrasion resistance are reduced.

[0043] The average particle size of resin (B) is preferably 0.001 to 0.250 μm, more preferably 0.001 to 0.150 μm, and even more preferably 0.001 to 0.100 μm. If the average particle size of resin (B) is less than the lower limit, the blocking resistance of the coating film will be slightly reduced. If the average particle size of resin (B) exceeds the upper limit, the adhesion of the coating film to the substrate (particularly adhesion to PP film), film-forming properties, and dispersion stability will be slightly reduced.

[0044] The resin (B) may be one produced by a known production method, or a commercially available product. Resin (B) can be obtained, for example, by modifying a polypropylene resin to introduce functional groups, followed by the use of an emulsifier or by self-emulsification. The method for modifying the modified polypropylene resin is not particularly limited, but examples thereof include a method of copolymerizing propylene with a monomer having a modifying group such as an unsaturated carboxylic acid, and, if necessary, one or more selected from other olefins and other monomers; and a method of introducing a monomer having a modifying group such as an unsaturated carboxylic acid into an unmodified polypropylene resin.

[0045] The unmodified polypropylene resin is a polymer obtained by homopolymerizing propylene, or a copolymer obtained by copolymerizing propylene with one or more selected from other olefins and other monomers. The method for introducing a monomer having a modifying group such as an unsaturated carboxylic acid into an unmodified polypropylene resin is not particularly limited, but examples thereof include a method in which the unmodified polypropylene resin and the monomer having a modifying group are melted at a temperature equal to or higher than the melting point of the unmodified polypropylene resin in the presence of a radical generator and allowed to react with each other; and a method in which the monomer having a modifying group is graft-copolymerized onto the unmodified polypropylene resin in the presence of a radical generator.

[0046] Commercially available resins (B) include, for example, the "Aptlock" series manufactured by Mitsubishi Chemical Corporation; the "Auroren" series manufactured by Nippon Paper Industries Co., Ltd.; the "Hardlen" series manufactured by Toyobo MC Co., Ltd.; and the "ZE-1224" series manufactured by CHEMIPAZ Corporation. The resin (B) may be used alone or in combination of two or more kinds.

[0047] <Aqueous medium (C)> Examples of the aqueous medium (C) include water and mixed solvents of water and organic solvents. The organic solvent is not particularly limited as long as it is soluble in water, and examples thereof include alcohol-based solvents such as methanol, ethanol, n-propanol, i-propanol, n-butanol, i-butanol, etc.; ketone-based solvents such as acetone; glycol ether-based solvents such as propylene glycol monomethyl ether, etc. One organic solvent may be used alone, or two or more organic solvents may be used in combination. The aqueous medium (C) preferably contains substantially no organic solvent.

[0048] <Hydrocarbon wax (D)> For the purpose of further improving the water friction resistance, abrasion resistance and blocking resistance of the coating film, the aqueous varnish composition may further contain a hydrocarbon wax (D). The hydrocarbon wax (D) is preferably a water-based wax. Aqueous waxes are waxes dispersed in water to form emulsions or dispersions. The hydrocarbon waxes dispersed in water may be any conventionally known wax, such as polyolefin wax, Fischer-Tropsch wax, paraffin wax, modified paraffin wax, and microcrystalline wax. Among these, polyolefin wax and Fischer-Tropsch wax are preferred, and polyolefin wax is more preferred. The hydrocarbon wax (D) may be used alone or in combination of two or more kinds.

[0049] Examples of polyolefin waxes include polyethylene wax and polypropylene wax. Among these, polyethylene wax is preferred. Examples of polyethylene waxes include high-density polymerized polyethylene, low-density polymerized polyethylene, oxidized polyethylene, acid-modified polyethylene, and special monomer-modified polyethylene. Fischer-Tropsch wax is a wax produced by the Fischer-Tropsch process using carbon monoxide and hydrogen as raw materials, and has a nearly saturated, unbranched, linear molecular structure.

[0050] The average particle size of the hydrocarbon wax (D) is preferably 10 μm or less, more preferably 6 μm or less, even more preferably 5 μm or less, and even more preferably 4 μm or less, and may be 0.1 μm or more, 0.5 μm or more, 1 μm or more, or 1.5 μm or more. If the average particle size of the hydrocarbon wax (D) exceeds the above upper limit, the adhesion of the coating film to the substrate, abrasion resistance, water abrasion resistance, and printability will be slightly reduced. When the hydrocarbon wax (D) is an aqueous wax, the average particle size of the dispersed particles in the aqueous wax can be considered to be the average particle size of the hydrocarbon wax (D) in the aqueous varnish composition.

[0051] The penetration (hardness) of the hydrocarbon wax (D) is preferably not more than 15, more preferably not more than 12, even more preferably not more than 10, even more preferably not more than 5, and particularly preferably not more than 3. If the penetration of the hydrocarbon wax (D) exceeds the upper limit above, the adhesion of the coating film to the substrate, water abrasion resistance, and abrasion resistance will be slightly reduced.

[0052] <Thickener (E)> A thickener (E) may be further contained in the aqueous varnish composition for the purposes of increasing the viscosity of the aqueous varnish composition and improving the stability of the aqueous varnish composition. Examples of the thickener (E) include polyurethane thickeners, polyacrylic thickeners, polyamide thickeners, cellulose thickeners, and clay minerals such as bentonite. Of these, polyurethane thickeners are preferred because of their excellent effect in improving the storage stability of the aqueous varnish composition, and among these, associative polyurethane thickeners (hereinafter also referred to as "polyurethane associative thickeners") are particularly preferred.

[0053] Associative thickeners are polymers that contain both hydrophobic and hydrophilic groups within their molecules. The hydrophobic groups of the thickeners interact with each other or with hydrophobic substances such as resins to form a network structure, further increasing the viscosity of the aqueous varnish composition. Furthermore, the viscosity of the aqueous varnish composition is also increased by the association of hydrophilic groups on the emulsion surfaces of resin (A) and resin (B) with the hydrophilic groups of the thickener. Examples of the hydrophobic group of the associative thickener include an alkyl group and a phenyl group. Examples of the hydrophilic group of the associative thickener include a hydroxy group, an amide group, and a carboxy group.

[0054] Examples of polyurethane associative thickeners include urethane-modified polyethers and polyether polyol-based urethane prepolymers.

[0055] Examples of commercially available polyurethane thickeners include the "SN Thickener" series manufactured by San Nopco Ltd. The thickener (E) may be used alone or in combination of two or more kinds.

[0056] <Hardening agent (F)> Examples of the curing agent (F) include aziridine-based curing agents, isocyanate-based curing agents, blocked isocyanate-based curing agents, carbodiimide-based curing agents, oxazoline-based curing agents, epoxy-based curing agents, etc. Among these, from the viewpoint of water-rub resistance of the coating film, aziridine-based curing agents, isocyanate-based curing agents, and epoxy-based curing agents are preferred, and aziridine-based curing agents are more preferred. The curing agent (F) may be used alone or in combination of two or more kinds.

[0057] Aziridine curing agents are compounds containing two or more aziridine groups per molecule. The aziridine groups react with the carboxyl groups in resin (A), causing a crosslinking reaction (curing reaction) of resin (A). The number of aziridine groups (number of functional groups) contained in one molecule of the aziridine curing agent is preferably 3 or more, since a network structure is formed when a crosslinking reaction with the resin (A) occurs, and further improvement in physical properties is expected, and from the viewpoint of stability when added, it is preferably 4 or less.

[0058] Examples of aziridine curing agents include 2,2-bishydroxymethylbutanol-tris[3-(1-aziridinyl)propionate], pentaerythritol-tris[3-(1-aziridinyl)propionate], and 4,4'-bis(ethyleneiminocarbonylamino)diphenylmethane.

[0059] Examples of commercially available aziridine curing agents include the "ChemiTite" series manufactured by Nippon Shokubai Co., Ltd. and the "Picassian" series manufactured by Stahl. The aziridine curing agent may be used alone or in combination of two or more kinds.

[0060] <Other optional ingredients> Other optional components may include known additives, such as binder resins other than the resin (A) and the resin (B) (hereinafter also referred to as "other binder resins"), antifoaming agents, surfactants, antisettling agents, UV absorbers, antioxidants, leveling agents, surface tension modifiers, rheology modifiers, light stabilizers, lubricants, dispersants, stabilizers, pH adjusters, fillers, antifungal agents, antistatic agents, metal fine particles, and magnetic powders. The other optional components may be used alone or in combination of two or more.

[0061] As the other binder resin, an aqueous binder resin other than the resin (A) and the resin (B) (hereinafter, also referred to as "other aqueous binder resin") is preferable. The other aqueous binder resins are not particularly limited, but examples thereof include water-soluble (meth)acrylic resins, dispersion-type (meth)acrylic resins, aqueous polyurethane resins, aqueous polyolefin resins, and aqueous polyester resins. The aqueous polyurethane resins, aqueous polyolefin resins, and aqueous polyester resins may each be of a water-soluble type, emulsion type, or dispersion type. The other binder resins may be used singly or in combination of two or more.

[0062] In consideration of visibility, it is preferable that the aqueous varnish composition be substantially free of colorants such as pigments. In this specification, "substantially free" means that it is not intentionally added.

[0063] <Content of each ingredient> The content of the resin (A) in terms of solid content is preferably from 24 to 38 mass %, more preferably from 26 to 36 mass %, and even more preferably from 28 to 34 mass %, relative to the total mass of the aqueous varnish composition. The content of the resin (A) in terms of solid content is preferably 76 to 90 mass %, more preferably 78 to 88 mass %, and even more preferably 80 to 86 mass %, based on the total solid content of the aqueous varnish composition. If the content of resin (A) is less than the above lower limit, the coating film will have slightly reduced blocking resistance, abrasion resistance (especially rubber abrasion resistance), and water abrasion resistance.If the content of resin (A) exceeds the above upper limit, the coating film will have slightly reduced adhesion to the substrate, acid resistance, and printability.

[0064] The content of the resin (B) in terms of solid content is preferably 0.5 to 6.0 mass %, more preferably 1.0 to 4.0 mass %, and even more preferably 1.5 to 3.5 mass %, relative to the total mass of the aqueous varnish composition. The content of the resin (B) in terms of solid content is 1.6 to 15.0 mass %, preferably 2.5 to 10.0 mass %, more preferably 4.0 to 8.0 mass %, relative to the total solid content of the aqueous varnish composition. If the content of resin (B) is less than the above lower limit, the coating film's adhesion to substrates (particularly adhesion to PP film), acid resistance, and printability will be reduced.If the content of resin (B) exceeds the above upper limit, the coating film's blocking resistance, abrasion resistance (particularly rubber abrasion resistance), and water abrasion resistance will be reduced.

[0065] The mass ratio (hereinafter also referred to as "B / A ratio") expressed in terms of solid content, represented by resin (B) / resin (A), is 0.020 to 0.180, preferably 0.030 to 0.150, and more preferably 0.050 to 0.110. If the B / A ratio is below the above lower limit, the adhesion of the coating film to the substrate (particularly adhesion to PP film) and acid resistance will decrease. If the B / A ratio exceeds the above upper limit, the blocking resistance, abrasion resistance, and water abrasion resistance of the coating film will decrease.

[0066] The content of the aqueous medium (C) is preferably 45 to 85 mass %, more preferably 50 to 80 mass %, and even more preferably 55 to 75 mass %, relative to the total mass of the aqueous varnish composition. If the content of the aqueous medium (C) is less than the above lower limit, the fluidity and printability of the aqueous varnish composition will be slightly reduced. If the content of the aqueous medium (C) exceeds the above upper limit, the blocking resistance and drying properties of the coating film will be slightly reduced.

[0067] When the aqueous varnish composition contains a hydrocarbon wax (D), the content of the hydrocarbon wax (D) in terms of solid content is preferably 0.1 to 3.0 mass %, more preferably 0.2 to 2.0 mass %, and even more preferably 0.3 to 1.0 mass %, relative to the total mass of the aqueous varnish composition. When the aqueous varnish composition contains a hydrocarbon wax (D), the content of the hydrocarbon wax (D) in terms of solid content is preferably 0.1 to 5.0 mass %, more preferably 0.5 to 3.0 mass %, and even more preferably 1.0 to 2.0 mass %, relative to the total solid content of the aqueous varnish composition. If the content of the hydrocarbon wax (D) is less than the above lower limit, the hydrocarbon wax (D) will not sufficiently improve the blocking resistance, abrasion resistance, and water abrasion resistance, whereas if the content of the hydrocarbon wax (D) exceeds the above upper limit, the printability will be slightly reduced.

[0068] When the aqueous varnish composition contains a thickener (E), the content of the thickener (E) in terms of solid content is preferably 0.01 to 1.00 mass%, more preferably 0.05 to 0.50 mass%, and even more preferably 0.10 to 0.30 mass%, relative to the total mass of the aqueous varnish composition. When the aqueous varnish composition contains a thickener (E), the content of the thickener (E) in terms of solid content is preferably 0.01 to 3.00 mass%, more preferably 0.10 to 1.00 mass%, and even more preferably 0.30 to 0.80 mass%, relative to the total solid content of the aqueous varnish composition. If the content of thickener (E) is less than the above lower limit, the effect of thickener (E) in improving the viscosity and storage stability of the aqueous varnish composition will not be fully manifested. If the content of thickener (E) exceeds the above upper limit, the printability of the aqueous varnish composition and the abrasion resistance and water abrasion resistance of the coating film will be slightly reduced.

[0069] When the aqueous varnish composition contains a curing agent (F), the content of the curing agent (F) in terms of solid content is preferably 0.1 to 5.0 mass%, more preferably 0.5 to 4.0 mass%, and even more preferably 1.0 to 3.0 mass%, relative to the total mass of the aqueous varnish composition. When the aqueous varnish composition contains a curing agent (F), the content of the curing agent (F) in terms of solid content is preferably 1.0 to 10.0 mass%, more preferably 2.0 to 9.0 mass%, and even more preferably 3.0 to 8.0 mass%, relative to the total solid content of the aqueous varnish composition. If the content of the curing agent (F) is less than the lower limit, the acid resistance, abrasion resistance, and water abrasion resistance of the coating film will be slightly reduced. If the content of the curing agent (F) exceeds the upper limit, the abrasion resistance and water abrasion resistance of the coating film will be slightly reduced.

[0070] The content of other optional components, calculated as solid content, is not particularly limited as long as it is within a range that does not impair the effects of the present invention, but for example, it is preferably 0 to 20 mass %, more preferably 0 to 15 mass %, and even more preferably 0 to 10 mass %, relative to the total mass of the aqueous varnish composition. If the aqueous varnish composition contains other optional components, the content of the other optional components, calculated as solids, is preferably 0.01% by mass or more, more preferably 0.10% by mass or more, and even more preferably 0.50% by mass or more, relative to the total mass of the aqueous varnish composition. If the content of the other optional components is less than the above lower limit, the effects of the other optional components will not be fully exerted.

[0071] <Manufacturing method> The aqueous varnish composition of this embodiment can be obtained, for example, by mixing resin (A), resin (B), optionally a further aqueous medium (C), optionally a hydrocarbon wax (D), optionally a thickener (E), optionally a curing agent (F), and optionally other optional components. The method for mixing the components is not particularly limited, and various methods can be used to mix the components. For example, resin (A), resin (B), optionally hydrocarbon wax (D), optionally thickener (E), optionally curing agent (F), and optionally other optional components can be dissolved or dispersed in aqueous medium (C). In particular, it is preferable to add curing agent (F) immediately before using the aqueous varnish composition.

[0072] The method for dissolving or dispersing each component in the aqueous medium (C) is not particularly limited, and can be carried out using a known disperser. Examples of dispersers include a paint shaker, ball mill, attritor, sand mill, bead mill, dyno mill, roll mill, ultrasonic mill, and high-pressure collision disperser. In this case, one type of disperser may be used to carry out the dispersion treatment once or multiple times, or two or more types of dispersers may be used in combination to carry out the dispersion treatment multiple times.

[0073] <Action and effect> The aqueous varnish composition of this embodiment described above contains the above-mentioned resin (A), resin (B), and aqueous medium (C), and since the content of resin (B) converted to solids is 1.0 to 15.0 mass %, it is possible to form a coating film that has excellent adhesion to substrates (especially adhesion to PP film), acid resistance, blocking resistance, and abrasion resistance (especially rubber abrasion resistance).

[0074] When using a modified polyethylene resin emulsion (hereinafter also referred to as "resin (B')") instead of resin (B), in order to achieve the same adhesion effect as resin (B), it is necessary to increase the content of resin (B') in the aqueous varnish composition in terms of solids (specifically, to make it more than 15.0 mass%). However, if the content of resin (B') increases, the blocking resistance, abrasion resistance, and water abrasion resistance of the coating film decrease. Resin (B) can impart sufficient adhesion to the coating film without increasing the content (specifically, even at 15.0% by mass or less), thereby achieving a good balance between adhesion to the substrate and blocking resistance, abrasion resistance, and water abrasion resistance.

[0075] Additionally, the aqueous varnish composition of this embodiment has excellent storage stability because the difference between the acid value of (A) and the acid value of (B) satisfies the above formula (1) or (2).

[0076] <Application> The aqueous varnish composition of this embodiment is suitable as a varnish for printing on the surface of any substrate such as a plastic film (or on the surface of any layer if such a layer is formed on the surface of the substrate). It is particularly suitable as a varnish for printing on the surface of a substrate or the surface of any layer by gravure printing or flexographic printing. In other words, the aqueous varnish composition of this embodiment is particularly suitable for gravure printing or flexographic printing. The aqueous varnish composition of this embodiment may be used as a varnish as is, or may be diluted with water or the like to be used as a varnish. The aqueous varnish composition of this embodiment is printed on any substrate to form a varnish layer. Hereinafter, a varnish layer formed using the aqueous varnish composition is also referred to as a printed layer.

[0077] [Laminate] An example of a laminate according to one embodiment of the present invention is shown in Figure 1. Note that the dimensional ratio in Figure 1 is different from the actual ratio for the sake of convenience of explanation. The laminate 10 in FIG. 1 is a printed matter comprising a plastic film 11 as a substrate and a varnish layer 12 provided on one surface of the plastic film 11.

[0078] <Plastic film> Examples of resins constituting the plastic film 11 include plastic films (substrate films) such as polyolefins (e.g., polyethylene (PE), milky polyethylene, polypropylene (PP), etc.), polyesters (e.g., polyethylene terephthalate (PET)), polystyrene (PS), oriented polypropylene (OPP), and polyamide (NY). Among these, polyolefins are preferred, and polypropylene is more preferred. That is, as the plastic film 11, polyolefin films are preferred, and polypropylene films are more preferred. These plastic films 11 may be used singly or in combination of two or more.

[0079] The plastic film 11 may have a single layer structure or a laminated structure. That is, the plastic film 11 may be a single layer film or a laminated film. When the plastic film 11 is a laminated film, it may be configured by laminating two or more films of the same type, or by laminating two or more films of different types. When the plastic film 11 is a laminated film, at least the layer in contact with the varnish layer 12 is preferably a polyolefin film, more preferably a polypropylene film.

[0080] The plastic film 11 may or may not be subjected to a corona treatment. The thickness of the plastic film 11 (thickness after lamination when two or more types are laminated together) is not particularly limited, and may be, for example, 10 to 50 μm.

[0081] <Varnish layer> In the illustrated laminate 10, the varnish layer 12 is provided on one side of the plastic film 11. The varnish layer 12 is a layer formed using the aqueous varnish composition of the present invention described above. The varnish layer 12 is a protective layer that protects the plastic film 11 . The varnish layer 12 may have a single layer structure or a multilayer structure. The thickness of the varnish layer 12 is not particularly limited and may be, for example, 0.1 to 1 μm. If the varnish layer contains particles (for example, particles of hydrocarbon wax (D)) and some of the particles protrude above the surface of the varnish layer, the thickness of the varnish layer is the thickness of the part where the particles do not protrude.

[0082] <Method of manufacturing laminate> The method for producing the laminate 10 of this embodiment includes a step of forming a varnish layer 12 on one surface of a plastic film 11 using the aqueous varnish composition of the present invention. In the manufacturing method of the laminate 10 of the present invention, for example, the aqueous varnish composition of the present invention is applied to one side of a plastic film 11 to form a coating film to form a laminate precursor, and then the coating film is dried to form a varnish layer 12. The aqueous varnish composition of the present invention may be applied to one side of the plastic film 11, the resulting coating film dried to form a varnish layer 12, and then the aqueous varnish composition of the present invention may be applied (reapplied) and the resulting coating film dried one or more times to form a varnish layer with a laminated structure. When the aqueous varnish composition of the present invention is applied in multiple coats, the compositions of the individual aqueous varnish compositions may be the same or different.

[0083] The varnish layer 12 may be formed by a known printing method. For example, the varnish layer 12 is formed by applying the aqueous varnish composition of the present invention to one surface of the plastic film 11 and drying it. The coating method may be a known coating method, such as gravure printing, flexographic printing, brush coating, gravure coater method, die coater method, bar coater method, spray coating method, flow coating method, dip coating method, spin coating method, and curtain coating method. Among these, gravure printing and flexographic printing are preferred from the viewpoint of excellent quality and productivity. Among these, flexographic printing is more preferred from the viewpoint of particularly excellent suitability for high-speed printing.

[0084] The method for drying the coating film is not particularly limited, and any known drying method can be used as long as it can remove the aqueous medium (C) contained in the aqueous varnish composition coated on one side of the plastic film 11. For example, natural drying or forced drying such as reduced-pressure drying, pressure drying, heat drying, or air drying may be used. When drying is performed by heating, the drying temperature is preferably 60 to 100°C.

[0085] <Action and effect> The laminate of the present embodiment described above has a varnish layer formed on one side of a plastic film using the aqueous varnish composition of the present invention, and has excellent acid resistance, blocking resistance, and abrasion resistance (especially rubber abrasion resistance). In addition, the varnish layer has excellent adhesion to the plastic film.

[0086] <Application> The laminate of this embodiment is suitable for use as a packaging material, particularly as a packaging label. Packaging labels are attached to containers such as plastic containers, metal containers, paper containers, etc. Examples of packaging labels include roll labels that are attached by wrapping them around the container and fastening them with adhesive, and shrink labels that are attached by applying heat and shrinking them to a shape that suits the shape of the container. When the laminate is used for a packaging label, the varnish layer side of the laminate is typically the inside of the packaging label, i.e., the container side, but the varnish layer side of the laminate may also be the outside of the packaging label, i.e., the visible side. If the varnish layer side of the laminate is on the inside of the packaging label, the varnish layer can protect the plastic film and the picture layer described below from contact with the container, etc. If the varnish layer side of the laminate is on the outside of the packaging label, the varnish layer can protect the plastic film from external contact, such as with human hands.

[0087] <Other embodiments> The laminate is not limited to the above-described embodiment. For example, as shown in Figure 2, the laminate 10 may further include a design layer 13 between the plastic film 11 and the varnish layer 12. That is, the laminate 10 may have the design layer 13 and the varnish layer 12 formed in this order on one side of the plastic film 11. The design layer 13 is typically a printed layer formed using ink. The ink may be a known ink. The ink typically contains a pigment. The method for forming the design layer 13 may be a known printing method, similar to the method for forming the varnish layer 12. When the laminate 10 has a design layer 13, ink is applied to one side of the plastic film 11 and dried to form the design layer 13, and then the aqueous varnish composition of the present invention is used to form the varnish layer 12 on this design layer 13. When forming the design layer 13, the ink may be applied multiple times to form a design layer 13 with a laminated structure.

[0088] 2 is provided over the entire surface of one side of the plastic film 11, but the pattern layer 13 is typically provided over only a portion of one side of the plastic film 11. That is, typically, one side of the plastic film 11 is partially exposed from the pattern layer 13, and this exposed surface comes into direct contact with the varnish layer 12, so that the plastic film 11 and the varnish layer 12 adhere closely to each other. When the laminate 10 has a pattern layer 13, the varnish layer 12 side of the laminate 10 is the back side of the laminate 10, i.e., the inside of the packaging label when the laminate 10 is used as a packaging label. The pattern layer 13 is protected by the varnish layer 12 from contact with the container, etc.

[0089] Furthermore, for example, as shown in FIG. 2, the laminate 10 may further include another layer 14 on the other surface of the plastic film 11. The other layer 14 is a protective layer that protects the plastic film 11 from external contact such as human hands. Examples of the other layer 14 include a varnish layer and a matte ink layer. In particular, if the other layer 14 is a matte ink layer, a matte design can be imparted to the laminate 10. The varnish layer on the other surface of the plastic film 11 may be formed using the aqueous varnish composition of the present invention, or may be formed using a known varnish. The matte ink layer is typically a printed layer formed using a matte ink. The matte ink may be any known matte ink. The matte ink typically contains a matting agent. The method for forming the other layer 14 may be a known printing method, similar to the method for forming the varnish layer 12 . When the laminate 10 includes the other layer 14, the side of the laminate 10 with the other layer 14 is the front side of the laminate 10, that is, the outside of the packaging label when the laminate 10 is used as a packaging label. The laminate 10 shown in Figure 2 comprises a plastic film 11 and a varnish layer 12, as well as a pattern layer 13 and other layers 14, but the laminate 10 may also comprise, in addition to the plastic film 11 and the varnish layer 12, either the pattern layer 13 or other layers 14.

[0090] [Packaging material] The packaging material of this embodiment includes the above-described laminate of the present invention. Specific examples of the packaging material include various packaging labels, such as plastic labels attached to packaging containers for beverages, foods such as prepared dishes and boxed lunches, and daily necessities such as cosmetics. Among these, the material is particularly suitable as a label for food and beverages. [Example]

[0091] The present invention will be explained in more detail below by way of examples, but the present invention is not limited to the following examples as long as it does not depart from the gist of the invention.

[0092] [Raw materials used] <(Meth)acrylic resin emulsion (A)> The compounds shown below were used as the (meth)acrylic resin emulsion (A) or comparative products thereof. A-1: Manufactured by CHEMIPAZ Corporation, product name "Hi-Loss-X 430F", non-volatile content: 41.5% by mass, acid value: 33 mg KOH / g, average particle size: 0.040 μm, minimum film formation temperature: less than 5°C, glass transition temperature: 21°C. A-2: Manufactured by BASF Japan Ltd., product name "Joncryl PDX-7511", non-volatile content: 45% by mass, acid value: 54 mg KOH / g, average particle size: 0.090 μm, minimum film formation temperature: less than 5°C, glass transition temperature: 9°C. A-3: Manufactured by BASF Japan Ltd., product name "Joncryl PDX-7440", non-volatile content: 48.5% by mass, acid value: 1 mg KOH / g, average particle size: 0.250 μm, minimum film formation temperature: 50°C, glass transition temperature: 40°C. A-4: Manufactured by BASF Japan Ltd., product name "Joncryl PDX-7780", non-volatile content: 48% by mass, acid value: 46 mg KOH / g, average particle size: 0.100 μm, minimum film formation temperature: over 50°C. A-5: CHEMIPAZ Corporation, product name "Hi-Loss-X TE-1336", non-volatile content: 39% by mass, acid value: 64 mg KOH / g, average particle size: 0.150 μm, minimum film formation temperature: less than 5°C. A comparison product with resin (A). A-6: CHEMIPAZ Corporation, product name "Hi-Loss-X RE-218", non-volatile content: 40% by mass, acid value: 49 mg KOH / g, average particle size: 0.035 μm, minimum film formation temperature: less than 5°C, glass transition temperature: 0°C. Comparative product to resin (A). A-7: CHEMIPAZ Corporation, product name "Hi-Loss-X TE-1124", non-volatile content: 60% by mass, acid value: 25 mg KOH / g, average particle size: 0.330 μm, minimum film formation temperature: less than 5°C. Comparative product to resin (A).

[0093] <Modified polypropylene resin emulsion (B)> The compounds shown below were used as the modified polypropylene resin emulsion (B) or a substitute therefor. B-1: Manufactured by Mitsubishi Chemical Corporation, trade name "Aptlock BW-5550", non-volatile content: 30% by mass, acid value: 18 mg KOH / g. B-2: Manufactured by Nippon Paper Industries Co., Ltd., product name "Auroren S-4891", non-volatile content: 30% by mass, acid value: 0 mg KOH / g. B-3: Manufactured by Nippon Paper Industries Co., Ltd., product name "Auroren S Series", non-volatile content: 25% by mass, acid value: 26 mg KOH / g. B-4: Toyobo MC Co., Ltd., product name "Hardlen NA-3002", non-volatile content: 30% by mass, acid value: 33 mg KOH / g. B-5: Manufactured by CHEMIPAZ Corporation, product name "ZE-1224", non-volatile content: 30% by mass, acid value: 50 mg KOH / g. B-6: Manufactured by Sumitomo Seika Chemicals Co., Ltd., product name "Zaixen AC", non-volatile content: 30% by mass, acid value: 62.2 mg KOH / g. Comparative product of resin (B).

[0094] <Aqueous medium (C)> As the aqueous medium (C), the following medium was used. ·C-1: Tap water.

[0095] <Hydrocarbon wax (D)> As the hydrocarbon wax (D), the following compound was used. D-1: Polyethylene wax (manufactured by Mitsui Chemicals, Inc., trade name "Chemipearl W-500", non-volatile content: 40% by mass, penetration: 10, average particle size: 2.5 μm). D-2: Polyethylene wax (manufactured by Mitsui Chemicals, Inc., trade name "Chemipearl W-410", non-volatile content: 40% by mass, penetration: 3, average particle size: 9.5 μm). D-3: Polyethylene wax, non-volatile content: 100% by mass, penetration: 13, average particle size: 2.2 μm.

[0096] <Thickener (E)> As the thickener (E), the following compound was used. E-1: Polyurethane associative thickener (manufactured by San Nopco Ltd., trade name "SN Thickener 612", non-volatile content: 40% by mass). E-2: Polyacrylic thickener (manufactured by BASF Japan Ltd., trade name "Rheovis AS1130", non-volatile content: 30% by mass).

[0097] <Hardening agent (F)> As the curing agent (F), the following compound was used. F-1: Aziridine-based curing agent (manufactured by Nippon Shokubai Co., Ltd., trade name "ChemiTite PZ-33", non-volatile content: 99% by mass). F-2: Epoxy curing agent (manufactured by Nagase ChemteX Corporation, trade name "Denacol EX-612", non-volatile content: 99% by mass).

[0098] <Other optional ingredients> As other optional components, the following compounds were used. Surfactant: Evonik, product name "TEGO WET 240", non-volatile content: 100% by mass. Antifoaming agent: BYK, product name "BYK-018", non-volatile content: 97% by mass.

[0099] [Evaluation method] <Evaluation of Adhesion> After applying cellophane tape (manufactured by Nichiban Co., Ltd.) to the surface of the varnish layer of the laminate, the cellophane tape was quickly peeled off and the condition of the varnish layer remaining on the plastic film (OPP film) was visually inspected and the adhesion of the varnish layer to the polyolefin film was evaluated according to the following evaluation criteria: 3 to 5 is considered pass. 5: The varnish layer has not peeled off at all. 4: The ratio of the area of ​​the peeled varnish layer to the area of ​​the cellophane tape is more than 0% and less than 10%. 3: The ratio of the area of ​​the peeled varnish layer to the area of ​​the cellophane tape is more than 10% and less than 30%. 2: The ratio of the area of ​​the peeled varnish layer to the area of ​​the cellophane tape is more than 30% and less than 50%. 1: The ratio of the area of ​​the peeled varnish layer to the area of ​​the cellophane tape is more than 50%.

[0100] <Evaluation of acid resistance> The laminate was immersed in a 1% by weight aqueous solution of hydrochloric acid and allowed to stand at 40°C for 24 hours. The laminate was then removed from the aqueous solution and the water droplets were wiped off. A friction test was then performed on the surface of the varnish layer of the laminate, using a Gakushin-type friction fastness tester (manufactured by Tester Sangyo Co., Ltd., product name "AB-301"), in which a white cloth (gold cloth No. 3) was rubbed back and forth 10 times under a load of 200 gf. The appearance of the varnish layer after the friction test was visually inspected, and the acid resistance of the varnish layer was evaluated according to the following evaluation criteria. A score of 3 to 5 was considered pass. 5: The varnish layer has not peeled off at all. 4: The ratio of the area of ​​the peeled varnish layer to the total area of ​​the varnish layer is more than 0% and less than 10%. 3: The ratio of the area of ​​the peeled varnish layer to the total area of ​​the varnish layer is more than 10% and less than 30%. 2: The ratio of the area of ​​the peeled varnish layer to the total area of ​​the varnish layer is more than 30% and less than 50%. 1: The ratio of the area of ​​the peeled varnish layer to the total area of ​​the varnish layer is more than 50%.

[0101] <Evaluation of storage stability> The viscosity of the aqueous varnish composition at 25°C was measured using Zahn cup #4. The aqueous varnish composition was then left to stand at 40°C for one week, after which the viscosity was measured at 25°C using Zahn cup #4 in the same manner, and the storage stability of the aqueous varnish composition was evaluated according to the following evaluation criteria. A score of 3 to 5 was considered acceptable. When the aqueous varnish composition contained a curing agent (F), the storage stability was evaluated using the aqueous varnish composition immediately before the curing agent (F) was added. 5: The viscosity increase after standing is less than 5 seconds compared to before standing. 4: The increase in viscosity after standing is more than 5 seconds but less than 10 seconds compared to before standing. 3: The increase in viscosity after standing is more than 10 seconds but less than 15 seconds compared to before standing. 2: The increase in viscosity after standing is more than 15 seconds and less than 30 seconds compared to before standing. 1: The viscosity after standing increased by more than 30 seconds compared to before standing, or gelation was confirmed.

[0102] <Evaluation of blocking resistance> Two laminate precursors were prepared. Two laminate precursors were stacked together so that the surface of the coating film side (printed surface) of one laminate precursor was in contact with the surface of the plastic film (OPP film) side (non-printed surface) of the other laminate precursor, and a pressure of 5 kg / cm was applied. 2 The samples were stored for 24 hours in a thermostatic chamber at a temperature of 40°C and humidity of 50% under a load of 1000 kJ / cm2. The two laminate precursors were then peeled away from each other, and the blocking resistance of the coating film was evaluated according to the following criteria. A rating of 3 to 5 was considered acceptable. Note that "varnish removal" below means that the coating film of one laminate precursor peeled off from the plastic film while the coating film of one laminate precursor remained attached to the opposing surface (in this evaluation, the non-printed surface of the other laminate precursor). 5: No varnish is removed from the non-printed surface. 4: The amount of varnish transferred to the non-printed surface is greater than 0% and less than 10% of the total area of ​​the coating film where the load is applied. 3: The amount of varnish transferred to the non-printed surface is more than 10% and less than 30% of the total area of ​​the coating film where the load is applied. 2: The amount of varnish transferred to the non-printed surface is more than 30% and less than 50% of the total area of ​​the coating film where the load is applied. 1: The amount of varnish transferred to the non-printed surface exceeds 50% of the total area of ​​the coating film where the load is applied.

[0103] <Evaluation of water friction resistance> A friction test was conducted on the surface of the varnish layer of the laminate using a Gakushin-type friction fastness tester (manufactured by Tester Sangyo Co., Ltd., product name "AB-301"), in which a white cloth (no. 3 gold cloth) moistened with water was rubbed back and forth 200 times under a load of 200 gf. After the friction test, the appearance of the varnish layer was visually inspected, and the water friction resistance of the varnish layer was evaluated according to the following evaluation criteria. A score of 3 to 5 was considered pass. 5: The area of ​​the varnish layer that was transferred to the white cloth (gold cloth No. 3) was 0% of the total area of ​​the varnish layer that was rubbed. 4: The percentage of the area of ​​the varnish layer that has transferred to the white cloth (gold cloth No. 3) is more than 0% and less than 5% of the total area of ​​the rubbed parts of the varnish layer. 3: The proportion of the area of ​​the varnish layer that has transferred to the white cloth (gold cloth No. 3) is more than 5% and less than 10% of the total area of ​​the rubbed parts of the varnish layer. 2: The proportion of the area of ​​the varnish layer that has transferred to the white cloth (gold cloth No. 3) is more than 10% and less than 30% of the total area of ​​the rubbed parts of the varnish layer. 1: The area of ​​the varnish layer that has transferred to the white cloth (gold cloth No. 3) is more than 30% of the total area of ​​the varnish layer that has been rubbed.

[0104] <Evaluation of friction resistance: Evaluation of resistance to fabric friction> A friction test was conducted on the surface of the varnish layer of the laminate using a Gakushin-type friction fastness tester (manufactured by Tester Sangyo Co., Ltd., product name "AB-301"), in which a white cloth (golden width No. 3) was rubbed back and forth 200 times under a load of 200 gf. After the friction test, the appearance of the varnish layer was visually inspected, and the resistance of the varnish layer to the cloth was evaluated according to the following evaluation criteria. A score of 3 to 5 was considered acceptable. 5: The area of ​​the varnish layer that was transferred to the white cloth (gold cloth No. 3) was 0% of the total area of ​​the varnish layer that was rubbed. 4: The percentage of the area of ​​the varnish layer that has transferred to the white cloth (gold cloth No. 3) is more than 0% and less than 5% of the total area of ​​the rubbed parts of the varnish layer. 3: The proportion of the area of ​​the varnish layer that has transferred to the white cloth (gold cloth No. 3) is more than 5% and less than 10% of the total area of ​​the rubbed parts of the varnish layer. 2: The proportion of the area of ​​the varnish layer that has transferred to the white cloth (gold cloth No. 3) is more than 10% and less than 30% of the total area of ​​the rubbed parts of the varnish layer. 1: The area of ​​the varnish layer that has transferred to the white cloth (gold cloth No. 3) is more than 30% of the total area of ​​the varnish layer that has been rubbed.

[0105] <Evaluation of friction resistance: Evaluation of rubber friction resistance> A friction test was conducted on the surface of the varnish layer of the laminate using a Gakushin-type friction fastness tester (manufactured by Tester Sangyo Co., Ltd., product name "AB-301"), in which rubber (chloroprene rubber, thickness: 1 mm) was rubbed back and forth 200 times under a load of 200 gf. After the friction test, the appearance of the varnish layer was visually inspected, and the rubber friction resistance of the varnish layer was evaluated according to the following evaluation criteria. A score of 3 to 5 was considered pass. 5: The percentage of the area of ​​the varnish layer that has migrated to the rubber side is 0% of the total area of ​​the varnish layer that has been rubbed. 4: The percentage of the area of ​​the varnish layer that has migrated to the rubber side is more than 0% and less than 5% of the total area of ​​the varnish layer that has been rubbed. 3: The percentage of the area of ​​the varnish layer that has migrated to the rubber side is more than 5% and less than 10% of the total area of ​​the varnish layer that has been rubbed. 2: The percentage of the area of ​​the varnish layer that has migrated to the rubber side is more than 10% and less than 30% of the total area of ​​the varnish layer that has been rubbed. 1: The area of ​​the varnish layer that has migrated to the rubber side is more than 30% of the total area of ​​the varnish layer that has been rubbed.

[0106] [Examples 1 to 17, Comparative Examples 1 to 10] <Preparation of aqueous varnish composition> According to the formulations shown in Tables 1 to 5, (meth)acrylic resin emulsion (A), modified polypropylene resin emulsion (B), aqueous medium (C), hydrocarbon wax (D), thickener (E), and other optional ingredients were mixed, and the resulting mixture was kneaded in a paint shaker. Curing agent (F) was then added, and the mixture was kneaded in a paint shaker to obtain an aqueous varnish composition. The curing agent (F) was added immediately before preparing the printing varnish in the following "Preparation of Laminate."

[0107] <Preparation of laminate> The plastic film used was a biaxially oriented polypropylene film (OPP film, manufactured by Futamura Chemical Co., Ltd., product name "FOR", thickness: 30 μm) that had been corona discharge treated on one side. For the corona discharge treatment, a corona discharge surface treatment device (manufactured by Wedge Corporation, product name "CTW-0212") was used. The prepared aqueous varnish composition was diluted with water so that the viscosity at 25°C, measured using Zahn cup #4, was 15 seconds, to prepare a varnish for printing. A flexo hand proofer equipped with an anilox roll with a cell volume of 6 cc was used as the applicator, and the coating weight after drying was 1.0 g / m 2 The prepared printing varnish was applied to the corona discharge-treated surface of a plastic film by flexographic printing, yielding a laminate precursor with a coating film formed on the plastic film. The laminate precursor was then dried at 20°C for 24 hours to yield a laminate (printed product) with a 0.5 μm-thick varnish layer formed on the plastic film. The storage stability was evaluated using the aqueous varnish composition, the blocking resistance was evaluated using the laminate precursor (before drying), and the adhesion, acid resistance, water friction resistance, and friction resistance were evaluated using the laminate (after drying).These results are shown in Tables 1 to 5.

[0108] [Table 1]

[0109] [Table 2]

[0110] [Table 3]

[0111] [Table 4]

[0112] [Table 5]

[0113] The blending amounts of each component other than the aqueous medium (C) in Tables 1 to 5 are calculated as solid contents. A blank cell in Tables 1 to 5 means that the component was not blended (amount blended: 0 mass %). The "balance" in Tables 1 to 5 is the amount of water (C-1) added so that the total amount (mass %) of all ingredients contained in the aqueous varnish composition becomes 100 mass %. In Tables 1 to 5, "acid value of (A) - acid value of (B)" means the acid value of the (meth)acrylic resin emulsion (A) minus the acid value of the modified polypropylene resin emulsion (B). "acid value of (B) - acid value of (A)" means the acid value of the modified polypropylene resin emulsion (B) minus the acid value of the (meth)acrylic resin emulsion (A). The "content of (B)" in Tables 1 to 5 is the content of the modified polypropylene resin emulsion (B) converted into solid content relative to the total solid content of the aqueous varnish composition, and is rounded to two decimal places. The "B / A ratio" in Tables 1 to 5 is the mass ratio expressed as modified polypropylene resin emulsion (B) / (meth)acrylic resin emulsion (A) converted into solid content, and is rounded to three decimal places.

[0114] As is clear from the results in Tables 1 to 3, the aqueous varnish compositions obtained in each Example had excellent storage stability. Furthermore, the coating films formed from these aqueous varnish compositions had excellent adhesion to polyolefin films, blocking resistance, acid resistance, cloth rub resistance, rubber rub resistance, and water rub resistance.

[0115] On the other hand, as is clear from the results in Tables 4 and 5, the coating film formed from the aqueous varnish composition obtained in Comparative Example 1, which used a (meth)acrylic resin emulsion with an acid value of 64 mgKOH / g, had poor acid resistance and water-rub resistance. The coating film formed from the aqueous varnish composition obtained in Comparative Example 2, which used a modified polypropylene resin emulsion with an acid value of 62.2 mgKOH / g, was poor in acid resistance and water rub resistance. The coating film formed from the aqueous varnish composition obtained in Comparative Example 3, which used a (meth)acrylic resin emulsion with an average particle size of 0.035 μm, was poor in blocking resistance. The coating film formed from the aqueous varnish composition obtained in Comparative Example 4, which used a (meth)acrylic resin emulsion with an average particle size of 0.330 μm, was poor in rubber abrasion resistance. The aqueous varnish composition obtained in Comparative Example 5, in which the acid value of (A) minus the acid value of (B) was 54.0, and the aqueous varnish composition obtained in Comparative Example 6, in which the acid value of (B) minus the acid value of (A) was 32.0, had poor storage stability. The coating film formed from the aqueous varnish composition obtained in Comparative Example 7, in which the content of the modified polypropylene resin emulsion (B) was 1.43 mass %, was poor in acid resistance. The coating film formed from the aqueous varnish composition obtained in Comparative Example 8, in which the content of modified polypropylene resin emulsion (B) was 15.85 mass %, was poor in blocking resistance, water abrasion resistance, and rubber abrasion resistance. The coating film formed from the aqueous varnish composition obtained in Comparative Example 9, in which the B / A ratio was 0.014, was poor in acid resistance. The coating film formed from the aqueous varnish composition obtained in Comparative Example 10, in which the B / A ratio was 0.185, was poor in blocking resistance, water rub resistance, cloth rub resistance, and rubber rub resistance. [Industrial Applicability]

[0116] The aqueous varnish composition of the present invention can form a coating film that has excellent adhesion to polyolefin films, acid resistance, and blocking resistance, and is also resistant to friction with rubber.It also has excellent storage stability, making it useful as a varnish for packaging materials, particularly packaging labels. [Explanation of symbols]

[0117] 10 Laminate 11 Plastic Film 12 varnish layer 13 Picture layer 14 Other layers

Claims

1. An aqueous varnish composition for gravure printing or flexographic printing, comprising a (meth)acrylic resin emulsion (A), a modified polypropylene resin emulsion (B), and an aqueous medium (C), the (meth)acrylic resin emulsion (A) has an acid value of 60 mgKOH / g or less and an average particle size of 0.038 to 0.300 μm; the acid value of the modified polypropylene resin emulsion (B) is 60 mgKOH / g or less, a difference between the acid value of the (meth)acrylic resin emulsion (A) and the acid value of the modified polypropylene resin emulsion (B) satisfies the following formula (1) or (2): the content of the modified polypropylene resin emulsion (B) in terms of solid content is 1.6 to 15.0 mass% based on the total solid content of the aqueous varnish composition; The aqueous varnish composition has a mass ratio of the modified polypropylene resin emulsion (B) to the (meth)acrylic resin emulsion (A) in terms of solid content of 0.020 to 0.

180. When the acid value of the (meth)acrylic resin emulsion (A) ≧ the acid value of the modified polypropylene resin emulsion (B): Acid value of (meth)acrylic resin emulsion (A)−Acid value of modified polypropylene resin emulsion (B)≦52 (1) In the case where the acid value of the (meth)acrylic resin emulsion (A) is less than the acid value of the modified polypropylene resin emulsion (B): Acid value of modified polypropylene resin emulsion (B)−Acid value of (meth)acrylic resin emulsion (A)≦30 (2)

2. 2. The aqueous varnish composition according to claim 1, wherein the (meth)acrylic resin emulsion (A) has a minimum film-forming temperature of 50°C or lower.

3. Further containing a hydrocarbon wax (D), 2. The aqueous varnish composition according to claim 1, wherein the hydrocarbon wax (D) has a penetration of 12 or less and an average particle size of 6 μm or less.

4. Further containing a thickener (E), 2. The aqueous varnish composition according to claim 1, wherein the thickener (E) is a polyurethane associative thickener.

5. Further containing a curing agent (F), 2. The aqueous varnish composition according to claim 1, wherein the curing agent (F) is an aziridine-based curing agent.

6. A laminate comprising a plastic film and a varnish layer formed on one surface of the plastic film using the aqueous varnish composition described in any one of claims 1 to 5.

7. The laminate according to claim 6, further comprising a design layer between the plastic film and the varnish layer.

8. A packaging material comprising the laminate according to claim 7.

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