Aqueous primer composition, laminate for packaging material, and method for producing laminate for packaging material

Abstract

To provide: an aqueous primer composition that exhibits excellent transferability to paper substrates and ink layers, as well as excellent leveling properties, and that also provides superior mottling resistance (gloss non-uniformity) when an active energy ray-curable composition is applied onto the aqueous primer layer; and a laminate for packaging material having an excellent decorative appearance (matte finish).SOLUTION: The present invention relates to an aqueous primer composition used to form a primer layer in a laminate for packaging material, the laminate including a paper substrate, a primer layer and an active energy ray-curable layer in this order. The aqueous primer composition comprises a binder resin, an extender pigment, and an aqueous solvent.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to an aqueous primer composition, a laminate for a packaging material, and a method for producing the laminate for a packaging material.

[0002] More specifically, the present invention relates to an aqueous primer composition for forming a primer layer of a laminate for a packaging material having a paper base material, a primer layer, and an active energy ray-curable layer in this order, the laminate for a packaging material, and a method for producing the laminate for a packaging material.

Background Art

[0003] In recent years, in the field of packages using a paper base material (also referred to as a paper container), for the purpose of imparting durability and cosmetic properties to printed matter, research has been actively conducted on applying a top-coating varnish after printing color ink on various base materials. Regarding paper container packages, when displayed in a store after printing, there are cases where glossiness is required for cosmetic purposes and cases where a matte finish (matte property) is required. In particular, in recent years, the demand for printed matter with a matte effect has been increasing. In addition, in the field of paper container packages, especially since they are also used for packaging high-class cosmetics and the like, the appearance (cosmetic property) quality of the printed matter affects the purchasing desire of customers through the production of a high-class feeling, so it is extremely important to ensure its quality. In addition to the top-coating varnish, there is also an expression such as overprint (OP) varnish, which is used synonymously with the top-coating varnish.

[0004] In addition, as a function of the top-coating varnish, not only the appearance such as the glossiness and matte property of the printed matter, but also the durability for protecting the printed pattern portion is required at the same time. Therefore, an active energy ray-curable coating liquid having excellent film strength is widely used.

[0005] As for the top coating varnish having a matting effect, various fine particles are often added to the coating liquid, and the fine particles present on the surface of the dried or cured coating film form irregularities, and the light is diffusely reflected at the interface to impart a matting feeling. On the other hand, when the substrate is a paper substrate, the solvent, low molecular weight components, resin components, etc. in the top coating varnish penetrate into the substrate, or due to transfer or leveling defects during printing, areas with a large number of fine particles and areas with few fine particles are formed like a pattern, resulting in uneven gloss values and uneven print appearance (mottling) becoming a problem.

[0006] Regarding the above problems, conventionally, for the purpose of suppressing the penetration of the top coating varnish into the paper substrate, a primer layer is often provided under the top coating layer. In particular, from the perspectives of reducing the work environment load and strengthening the chemical substance management regulations and environmental protection in various countries in recent years, the demand for water-based types of primers (water-based primers) is still high instead of oil-based types using organic solvents. In addition to primers, there are also notations such as anchor varnish and sealing varnish, but all are used synonymously with primers.

[0007] Patent Document 1 proposes a laminate in which an aqueous anchor varnish containing a styrene-butadiene rubber emulsion with a glass transition temperature of 5°C is applied onto an aqueous printing ink layer printed on a paper substrate, and then an active energy ray-curable overprint varnish is applied.

[0008] Also, Patent Document 2 proposes a method in which a solid color layer and a primer layer made of a two-component curable urethane resin composed of an acrylic polyol and an isocyanate are sequentially laminated onto a fibrous substrate, and then a surface protection layer is laminated. However, Patent Documents 1 and 2 still have problems with the transferability and leveling property of the water-based primer on the ink layer, and the transfer and leveling property and matting property (matting feeling) of the active energy ray-curable composition onto the water-based primer layer.

Prior Art Documents

Patent Documents

[0009]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0010] The present invention provides an aqueous primer composition excellent in transferability to a paper substrate and an ink layer and leveling property, and excellent in mottling resistance (gloss unevenness) when an active energy ray-curable composition is applied on the aqueous primer layer, and a laminate for packaging materials excellent in cosmetic appearance (matting property).

Means for Solving the Problems

[0011] The present invention relates to an aqueous primer composition for forming the primer layer of a laminate for packaging materials, which sequentially has a paper substrate, a primer layer, and an active energy ray-curable layer, and relates to an aqueous primer composition containing a binder resin, an extender pigment, and an aqueous solvent.

[0012] The present invention also relates to the aqueous primer composition having a surface tension of 24 to 38 mN / m.

[0013] The present invention also relates to the aqueous primer composition having a surface free energy of the primer layer of 24 to 40 dyne / cm.

[0014] The present invention also relates to the aqueous primer composition in which the aqueous solvent contains a hydrophilic organic solvent.

[0015] The present invention also relates to the aqueous primer composition having a viscosity of 50 to 2500 mPa·s.

[0016] Furthermore, the present invention relates to the aqueous primer composition, wherein the binder resin contains at least one selected from the group consisting of an aqueous acrylic resin (A), an aqueous urethane resin (B), and an aqueous polyester resin (C).

[0017] Furthermore, the present invention relates to the aqueous primer composition, wherein the extender pigment contains at least one selected from the group consisting of silica, calcium carbonate, barium sulfate, and talc.

[0018] Furthermore, the present invention relates to the aqueous primer composition, wherein the average particle diameter of the extender pigment is 1 to 10 μm.

[0019] Furthermore, the present invention relates to the aqueous primer composition, wherein the boiling point of the hydrophilic organic solvent is 70 to 90°C.

[0020] Furthermore, the present invention relates to the aqueous primer composition, which is for flexo or gravure printing.

[0021] Furthermore, the present invention is a laminate for packaging materials having, in order, a paper substrate, a primer layer formed from the aqueous primer composition, and an active energy ray-curable layer, wherein the active energy ray-curable layer contains resin fine particles, and relates to the laminate for packaging materials.

[0022] Furthermore, the present invention relates to the laminate for packaging materials, which further has an offset printing layer.

[0023] Furthermore, the present invention relates to the laminate for packaging materials, wherein the 60-degree specular glossiness of the active energy ray-curable layer is 40 or less.

[0024] Furthermore, the present invention is a method for manufacturing a laminate for packaging materials having, in order, a paper substrate, a primer layer, and an active energy ray-curable layer, A method for manufacturing a laminate for packaging materials includes a step of forming the primer layer by flexographic or gravure printing an aqueous primer composition containing a binder resin, an extender pigment, and an aqueous solvent on a paper substrate, and a step of forming the active energy ray-cured layer by irradiating the active energy ray after printing the active energy ray-curable composition on the primer layer.

Advantages of the Invention

[0025] The present invention provides an aqueous primer composition excellent in transferability to a paper substrate and an ink layer and leveling property, and excellent in mottling resistance (gloss unevenness) when an active energy ray-curable composition is applied on the aqueous primer layer, and a laminate for packaging materials excellent in cosmetic appearance (matte property) and scratch resistance.

Embodiments for Carrying Out the Invention

[0026] Hereinafter, embodiments of the present invention will be described in detail. However, the description of the constituent elements described below is an example (representative example) of the embodiments of the present invention, and the present invention is not limited to these contents unless it exceeds the gist thereof.

[0027] In this specification, the "aqueous primer composition" may sometimes be simply referred to as the "primer composition" and they are synonymous. The "laminate for packaging materials" may sometimes be simply referred to as the "laminate" and they are synonymous. Also, in this specification, "mN / m" is used as the unit of the surface tension of a liquid such as the primer composition, and "dyne / cm" is used as the unit of the surface tension of a solid such as the primer layer, that is, the surface free energy. Although the units are different, the values are equivalent. For example, when comparing the surface energy of the primer layer and the surface tension of the active energy ray-curable composition, the numerical values can be compared as they are.

[0028] Hereinafter, the present invention will be described in detail.

[0029] <Aqueous Primer Composition> The present invention relates to an aqueous primer composition for forming a primer layer of a laminate for packaging materials, which sequentially has a paper substrate, a primer layer, and an active energy ray-curable layer, and the aqueous primer composition contains a binder resin, an extender pigment, and an aqueous solvent. The aqueous primer composition is preferably used on a paper substrate and / or an ink layer optionally formed on the paper substrate, and is preferably used as a primer layer of the active energy ray-curable layer. When the aqueous primer composition contains an extender pigment, the penetration of the active energy ray-curable composition for forming the active energy ray-curable layer into the paper substrate is suppressed, and the build-up and leveling of the active energy ray-curable layer are stabilized. Therefore, gloss unevenness (motling) is less likely to occur, and a uniform and high-class appearance (matte feeling) can be obtained. When the surface tension of the aqueous primer composition is 24 to 38 mN / m, the above effects are more easily obtained, which is preferable. However, the above action mechanism is based on speculation and does not particularly limit the present invention.

[0030] (Surface tension of the aqueous primer composition) In the present invention, the surface tension of the aqueous primer composition is preferably 24 to 38 mN / m, more preferably 26 to 36 mN / m, and still more preferably 27 to 33 mN / m. When it is 24 mN / m or more, a decrease in the surface free energy of the primer layer is prevented, and the transfer, build-up, and leveling properties of the active energy ray-curable composition on the primer layer are improved. When it is 38 mN / m or less, the wettability with respect to the paper substrate and the ink layer is improved, and repelling can be suppressed.

[0031] As means for setting the surface tension of the aqueous primer composition within the above range, there is a method of adjusting the type and addition amount of extender pigments. For example, extender pigments are preferably used in the preferred forms described later. Further, when a hydrophilic organic solvent is added, the surface tension tends to decrease, and the hydrophilic organic solvent is preferably used in the preferred forms described later. Also, it is possible to adjust with additives such as surface modifiers, and when a surface modifier is added, the surface tension tends to decrease. It can be adjusted to a predetermined range by appropriately selecting from these means.

[0032] When the surface tension of the aqueous primer composition is adjusted only with additives, the additives remain in the primer layer formed by printing and drying the composition, and the surface free energy of the primer layer becomes low. Therefore, when printing an active energy ray-curable composition on the primer layer, leveling defects are likely to occur. Therefore, by using a hydrophilic organic solvent in combination in the aqueous primer composition, while having the effect of lowering the surface tension of the aqueous primer composition, it volatilizes after drying and does not remain in the primer layer, and does not lower the surface free energy of the primer layer. Therefore, it is more preferable because it is easy to achieve both leveling of the aqueous primer composition on the paper substrate and the ink layer and leveling of the active energy ray-curable composition on the primer layer. The above functions and mechanisms are based on consideration and do not particularly limit the present invention.

[0033] (Method for measuring surface tension) The surface tension can be measured, for example, using a high-precision surface tensiometer DY-700 (manufactured by Kyowa Interface Science Co., Ltd.). In the present invention, the liquid temperature at the time of measurement was 25°C.

[0034] <Primer layer> The primer layer of the present invention is formed by an aqueous primer composition. The surface energy of the primer layer is preferably 24 to 40 dyne / cm, more preferably 26 to 38 dyne / cm, and even more preferably 30 to 38 dyne / cm. When within the above range, the surface energy of the primer layer becomes lower than the surface tension of the active energy ray-curable composition, and the wetting spread of the active energy ray-curable composition on the primer layer is improved. When it is 24 dyne / cm or more, the transfer, anchoring, and leveling properties of the active energy ray-curable composition to the aqueous primer layer are good. When it is 40 dyne / cm or less, the surface tension of the primer composition is concomitantly reduced, so that repulsion on the base material and the ink layer is suppressed, and a good matte feeling can be obtained.

[0035] As a means for setting the surface free energy of the primer layer within the above range, there is a method of adjusting the type and addition amount of the extender pigment, and it is preferably used in the preferred form described later. In addition, when the addition amount of the extender pigment increases, the surface free energy tends to increase, and when the particle diameter of the extender pigment decreases, the surface free energy tends to increase. Further, there are a method of selecting the type of binder resin, a method of adjusting with additives such as a surface conditioner, etc., and these means can be appropriately selected and adjusted to a predetermined range.

[0036] In order to set the surface free energy of the primer layer within the above range, as the binder resin, it is preferable to contain at least one selected from the group consisting of an aqueous acrylic resin (A), an aqueous urethane resin (B), and an aqueous polyester resin (C). Among them, the aqueous acrylic resin (A) is preferable, and two or more resins may be used in combination within a range not impairing the effects of the present invention. By using the above binder resin, it becomes easier to balance the surface free energy of the primer layer and the surface tension of the active energy ray-curable composition, and the transfer, anchoring, and leveling properties of the active energy ray-curable composition to the primer layer are improved. The mass ratio of the binder resin in the aqueous primer composition is preferably 10 to 50% by mass, more preferably 20 to 40% by mass. The mass ratio of the binder resin in the primer layer is preferably 60 to 95% by mass, more preferably 70 to 85% by mass.

[0037] (Method for measuring surface free energy) Here, the above-mentioned surface free energy is defined as "the free energy possessed by a unit area of the surface" and is the energy that the primer layer surface has in excess compared to the inside of the layer (bulk). The larger the surface free energy of a solid, the easier it is for gases and fine particles to be adsorbed, the easier it is for liquids to wet, and the easier it is to adhere to other solids. The surface free energy can be measured by analyzing the contact angles of water and hexadecane using the Kaelble-Uy method with a contact angle meter or the like. In the present invention, the surface free energy of the above primer layer is a value calculated by the following method using a fully automatic contact angle meter DM-701 manufactured by Kyowa Interface Science Co., Ltd. First, 1 μL of water (pure water) was dropped onto the primer layer surface, and the contact angle after 30 seconds was measured. Then, similarly, the contact angle was measured using n-hexadecane instead of water. The surface free energy was calculated by the Kaelble-Uy method using the obtained contact angles of water and n-hexadecane.

[0038] <Binder resin> As the binder resin, known resins can be used. However, from the viewpoints of substrate adhesion and film strength of the primer layer, etc., it is preferably at least one selected from the group consisting of aqueous acrylic resin (A), aqueous urethane resin (B), and aqueous polyester resin (C). Among them, aqueous acrylic resin (A) is preferred. Also, two or more resins may be used in combination within a range that does not impair the effects of the present invention.

[0039] The mass ratio of the binder resin in the aqueous primer composition is 10 to 50% by mass. More preferably, it is 20 to 40% by mass. When it is within the above range, the matting property and abrasion resistance are good.

[0040] (Aqueous acrylic resin (A)) The aqueous acrylic resin (A) is a general term for an aqueous acrylic emulsion (A1) and a water-soluble acrylic resin (A2) (however, those having a urethane bond are excluded). The aqueous acrylic resin (A) is a resin containing (meth)acrylate units, and examples thereof include polymers or copolymers of acrylic monomers such as alkyl (meth)acrylates, (meth)acrylic acid, (meth)acrylamide, and copolymers of the above acrylic monomers and monomers such as styrene and maleic anhydride. The acrylic monomer may have a functional group such as a hydroxyl group, a carboxyl group, or a glycidyl group. Preferred examples of the acrylic monomer include acrylic acid esters and methacrylic acid esters. For example, examples of the acrylic acid ester include methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, hexyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, benzyl acrylate, dimethylaminoethyl acrylate, hydroxyethyl acrylate, hydroxypropyl acrylate, glycidyl acrylate, etc. Preferred examples of the methacrylic acid ester include methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, hexyl methacrylate, 2-ethylhexyl methacrylate, cyclohexyl methacrylate, benzyl methacrylate, dimethylaminoethyl methacrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, glycidyl methacrylate, etc. In addition, carboxylic acid-containing monomers such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, fumaric acid, itaconic acid, or their anhydrides and half-esters can also be used. Among the above, it is preferable that the acrylic monomer contains methyl acrylate, ethyl acrylate, hexyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, hexyl methacrylate, 2-ethylhexyl methacrylate, cyclohexyl methacrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, acrylic acid, methacrylic acid, maleic acid, and itaconic acid. In addition, examples of the styrene monomer constituting the styrene-acrylic resin include styrene, α-methylstyrene, β-methylstyrene, etc. Among them, the styrene monomer preferably contains α-methylstyrene.

[0041] The mass ratio of the aqueous acrylic resin (A) in the binder resin is preferably 60 to 100% by mass, more preferably 80 to 100% by mass, and particularly preferably 90 to 100% by mass. When within the above range, the adhesion and scratch resistance are good.

[0042] (Aqueous acrylic emulsion (A1)) The aqueous acrylic emulsion (A1) contains at least one selected from a styrene-acrylic resin and an acrylic resin (excluding the case where it is a styrene-acrylic resin). Among them, it preferably contains a styrene-acrylic resin. The acrylic monomers constituting the acrylic resin can preferably use the same ones as above. Note that an emulsion refers to a form in which the resin itself is insoluble or hardly soluble in water, but the resin is dispersed in small particle form and stabilized. Also, a copolymer emulsion obtained by copolymerizing the above monomers using a water-soluble acrylic resin as a polymer emulsifier can also be preferably used.

[0043] The average particle diameter of the aqueous acrylic emulsion (A1) is preferably 10 to 500 nm, still preferably 20 to 300 nm, and even more preferably 30 to 250 nm. The average particle diameter can be measured, for example, as the D50 value by the dynamic light scattering method. In addition, the weight average molecular weight of the aqueous acrylic emulsion (A1) is preferably 2000 to 2000000, still preferably 5000 to 1500000, and even more preferably 10000 to 100000. This is because when within the above range, the cohesive force of the coating film is improved and the scratch resistance is improved. As the styrene-acrylic resin, for example, Joncryl PDX-7734 (Tg 40°C, solid content 41.4% by mass), Joncryl PDX-7538 (Tg 75°C, solid content 45.5% by mass), etc. manufactured by BASF can be used. Also, as the acrylic resin, Joncryl 60J, 70J, HPD-196, etc. manufactured by BASF can be used.

[0044] (Water-soluble acrylic resin (A2)) The water-soluble acrylic resin (A2) is preferably at least one selected from a styrene-acrylic resin and an acrylic resin (excluding the case where it is a styrene-acrylic resin), and has a hydrophilic group such as a carboxyl group. Further, it is preferably a water-soluble resin in which the hydrophilic group is solubilized by a basic compound. Examples of the basic compound preferably include an amine compound and an alkali metal. Specifically, examples of the amine compound include alkylamines such as ammonia, diethylamine, triethylamine, and ethylenediamine, and alkanolamines such as monoethanolamine, ethylethanolamine, diethylethanolamine, diethanolamine, and triethanolamine. Examples of the alkali metal include sodium hydroxide and potassium hydroxide.

[0045] The acid value of the water-soluble acrylic resin (A2) is preferably 150 to 300 mgKOH / g, and more preferably 180 to 260 mgKOH / g. When it is within the above range, the dispersion stability of the extender pigment is improved, the leveling during transfer is improved, and the mottling resistance is good. The weight average molecular weight of the water-soluble acrylic resin (A2) is preferably 1500 to 60000, and more preferably 4000 to 30000. When it is within the above range, the dispersion stability of the extender pigment is improved, the leveling during transfer is improved, and the mottling resistance is good. As the water-soluble acrylic resin (A2), for example, Acrys TYS-85, TYS-3000, LH52 manufactured by Gifu Celac Co., Ltd., Johncryl 60J, 70J, HPD-196, HPD-96J manufactured by BASF Co., Ltd. etc. can be used.

[0046] The mass ratio (A1 / A2) of the aqueous acrylic emulsion (A1) and the water-soluble acrylic resin (A2) in the aqueous acrylic resin (A) is preferably 95 / 5 to 50 / 50, and preferably 90 / 10 to 60 / 40. Being in the above range makes the adhesion and abrasion resistance good.

[0047] (Aqueous urethane resin (B)) The aqueous urethane resin (B) is a general term for an aqueous urethane emulsion (B1) and a water-soluble urethane resin (B2) without limitation as long as it is an aqueous resin containing a urethane bond. Also, an embodiment further containing a urea bond is also preferable for the aqueous urethane resin (B).

[0048] In the present invention, the aqueous urethane resin (B) includes a urethane acrylic resin containing both an acrylic resin part and a urethane resin part. Also, an embodiment having a urea bond is also preferable.

[0049] As the aqueous urethane resin (B), a form which is a urethane resin synthesized from a polyol, a polyhydroxy acid and a polyisocyanate, or a urethane urea resin which is an embodiment of an aqueous urethane resin, a form which is a urethane resin chain-extended with a polyamine and a urethane prepolymer having an isocyanate group at the terminal synthesized from a polyol, a polyhydroxy acid and a polyisocyanate is preferable. In the production of the water-soluble urethane resin (B2), when reacting a polyol and a polyisocyanate, it is preferable to introduce acidic groups such as carboxyl groups and sulfone groups into the resin and neutralize with a basic compound to make it water-soluble. From the viewpoint of water resistance, the carboxyl group is preferable as the acidic group.

[0050] (Polyol) Examples of the above polyol include, but are not limited to, polyester polyol, polyether polyol, polylactone polyol, polycarbonate polyol, polyolefin polyol, dimer diol, hydrogenated dimer diol, etc. These polyols may be used alone or in combination of two or more. The aqueous urethane resin preferably contains a structural unit composed of at least one polyol selected from polyester polyol, polyether polyol, and polycarbonate polyol. More preferably, the polyol is polyester polyol, polyether polyol, or polycarbonate polyol. The number average molecular weight of the polyol is preferably 500 to 5000.

[0051] (Polyether polyol) Examples of the above polyether polyol include polyethylene glycol, polypropylene glycol, polytrimethylene glycol, polytetramethylene glycol, and copolymers thereof. The aqueous urethane resin preferably contains a structural unit composed of polyether polyol. In one embodiment, the aqueous urethane resin (B) preferably contains a structural unit derived from polyethylene glycol, and preferably contains 0.1 to 25% by mass, more preferably 2 to 15% by mass, and still more preferably 2 to 10% by mass of the structural unit derived from polyethylene glycol in the total mass of the aqueous urethane resin.

[0052] (Polyester polyol) As the above polyester polyol, a form having a structural unit derived from a polyester polyol which is a condensate of a dibasic acid and a diol containing a branched diol is preferable. As the dibasic acid, sebacic acid, adipic acid, succinic acid and the like can be preferably used, and as the branched diol, those in which at least one of the hydrogens on the carbon of the alkylene glycol has a substituent are meant. Specifically, at least one selected from propylene glycol, 3-methyl-1,5-pentanediol, neopentyl glycol, 2-butyl-2-ethyl-1,3-propanediol, 2-methyl-1,3-propanediol is preferably contained in an amount of 50% by mass or more, more preferably 60% by mass or more in the total mass of the diol. The embodiments of the polyester polyol are not limited to these.

[0053] (Polycarbonate polyol) The above polycarbonate polyol is not limited by the production method and the diol species constituting the polycarbonate polyol, but preferably includes a polycondensate obtained by a transesterification reaction between a diol composed of an alkylene glycol and a carbonate compound. The polycarbonate polyol is preferably an alicyclic and / or aliphatic polycarbonate diol.

[0054] Examples of the diol include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 2-methyl-1,3-propanediol, neopentyl glycol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, 1,8-octanediol, 1,9-nonanediol, 2-methyl-1,8-octanediol, 1,10-decanediol, 2-butyl-2-ethyl-1,3-propanediol, 1,4-butynediol, 2,2,4-trimethyl-1,3-pentanediol, 1,4-cyclohexanedimethanol, diethylene glycol, polypropylene glycol, dipropylene glycol, etc. These can be used alone or in admixture of two or more. It is preferable that the polycarbonate polyol is 3-methyl-1,5-pentanediol or a diol structure having a branched structure such as others. The carbonate compound is not particularly limited, and examples thereof include dialkyl carbonate, diaryl carbonate, or alkylene carbonate. Specific examples of the carbonate compound include dialkyl carbonates such as dimethyl carbonate, diethyl carbonate, and dibutyl carbonate, diaryl carbonates such as diphenyl carbonate, and alkylene carbonates such as ethylene carbonate.

[0055] (Polyisocyanate) Examples of the polyisocyanate preferably include aromatic diisocyanate, aliphatic diisocyanate, alicyclic diisocyanate, etc. These may form a trimer to have an isocyanurate ring structure. Examples of the aromatic diisocyanate include 1,5-naphthylene diisocyanate, 4,4'-diphenylmethane diisocyanate (MDI), 4,4'-diphenyldimethylmethane diisocyanate, 4,4'-dibenzyl isocyanate, dialkyldiphenylmethane diisocyanate, tetraalkyldiphenylmethane diisocyanate, 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate, tolylene diisocyanate, etc. Examples of aliphatic diisocyanates include butane-1,4-diisocyanate, hexamethylene diisocyanate, isopropylene diisocyanate, methylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, lysine diisocyanate, etc. Examples of alicyclic diisocyanates include cyclohexane-1,4-diisocyanate, xylylene diisocyanate, isophorone diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, 1,3-bis(isocyanatomethyl)cyclohexane, methylcyclohexane diisocyanate, norbornane diisocyanate, m-tetramethylxylylene diisocyanate, hydrogenated 4,4-diphenylmethane diisocyanate, dimer diisocyanate obtained by converting the carboxyl group of dimer acid into an isocyanate group, etc. Among them, preferably at least one selected from tolylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, bis(isocyanatomethyl)cyclohexane, hexamethylene diisocyanate, and a trimer of hexamethylene diisocyanate. These polyisocyanates can be used alone or in combination of two or more.

[0056] (Polyhydroxy acid) The above polyhydroxy acid is not limited to the following, but polyols containing carboxyl can be used. For example, dimethylolalkanoic acids such as 2,2-dimethylolpropionic acid, 2,2-dimethylolbutyric acid, 2,2-dimethylolvaleric acid, etc. are preferably mentioned. These can be used alone or in combination of two or more. The polyhydroxy acid is used in the production process of the aqueous urethane resin, and its carboxyl group is introduced into the obtained urethane resin to have an acid value. The unreacted carboxyl group is neutralized and made aqueous.

[0057] (Polyamine) Examples of compounds that can be used as the above polyamine include various known amines. For example, 2-hydroxyethylethylenediamine, 2-hydroxyethylpropylenediamine, di-2-hydroxyethylethylenediamine, di-2-hydroxyethylpropylenediamine, 2-hydroxypropyl ethylenediamine, di-2-hydroxypropyl ethylenediamine, ethylenediamine, propylenediamine, hexamethylenediamine, isophoronediamine, dicyclohexylmethane-4,4'-diamine, and dimer diamine obtained by converting the carboxyl group of dimer acid to an amino group are preferably mentioned. These can be used alone or in combination of two or more.

[0058] (Reaction terminator) A reaction terminator can also be used in combination with the above polyamine. Examples of such reaction terminators include dialkylamines such as di-n-dibutylamine, monoethanolamine, diethanolamine, 2-amino-2-methyl-1-propanol, tris(hydroxymethyl)aminomethane, 2-amino-2-ethyl-1,3-propanediol, amines having a hydroxyl group such as N-di-2-hydroxyethylethylenediamine, N-di-2-hydroxyethylpropylenediamine, N-di-2-hydroxypropyl ethylenediamine, and further monoamine-type amino acids such as glycine, alanine, glutamic acid, taurine, aspartic acid, aminobutyric acid, valine, aminocaproic acid, aminobenzoic acid, aminoisophthalic acid, and sulfamic acid.

[0059] (Neutralizing agent) For the water dispersion of the aqueous urethane resin (B), it is preferable to neutralize the carboxyl group in the resin with a basic compound.

[0060] (Basic compound) Examples of the basic compound include ammonia; organic amines such as monoethylamine, diethylamine, trimethylamine, triethylamine, triisopropylamine, tributylamine, triethanolamine, methyldiethanolamine, monoethanolamine, dimethylethanolamine, diethylethanolamine, morpholine, N-methylmorpholine, 2-amino-2-ethyl-1-propanol; and inorganic alkalis such as sodium hydroxide and potassium hydroxide. One or more of them may be used in combination. However, in order to improve the water resistance of the film after drying, those with high volatility that are water-soluble and easily dissociated by heat are preferred, and ammonia, trimethylamine, and triethylamine are particularly preferred. Moreover, the acid value of the aqueous urethane resin (B) is preferably 5 to 100 mgKOH / g, and more preferably 10 to 60 mgKOH / g. These acid values are neutralized with the above basic compound to be made aqueous.

[0061] When the aqueous urethane resin (B) is a urethane acrylate resin, the acrylic resin part and the urethane resin part may be an alternating copolymer, or a so-called graft polymer in which the main chain is a urethane resin part and the side chain is an acrylic resin part or the main chain is an acrylic resin part and the side chain is a urethane resin part. In the aqueous urethane emulsion resin (B1), it may have a core / shell type in which the core part is an acrylic resin part and the shell part is a urethane resin part, or a sea-island structure in which the sea part is an acrylic resin part and the island part is a urethane resin part.

[0062] The average particle size of the aqueous urethane emulsion (B1) preferably ranges from 20 nm to 400 nm, and more preferably from 30 nm to 200 nm.

[0063] Specific examples of the aqueous urethane emulsion (B1) include Takelac W-5030, W-5661, W-6010, W-6020, W-6061, W-6355, W-605, WPB-341(30), WS-4022 (manufactured by Mitsui Chemicals, Inc.), WEM-200U, WEM-3000, WEM-505C (manufactured by Daiso Fine Chemical Co., Ltd.), Aquabrid 46777, 3756, UX-100, UX-110, AST531, AST49 (manufactured by Daicel Miraiz Co., Ltd.), and the like.

[0064] The aqueous urethane resin (B2) is appropriately manufactured by a known method. For example, the acetone method using an organic solvent that is inert to isocyanate and hydrophilic, the solvent-free synthesis method that does not use any solvent, and the like can be mentioned. For example, the method described in JP-A-2013-234214 can be appropriately used.

[0065] (Aqueous polyester resin (C)) The aqueous polyester resin (C) preferably has a form of a polyester resin synthesized by a polycondensation reaction (esterification reaction) of a polybasic acid and / or its anhydride and a polyhydric alcohol. This reaction may be carried out either under normal pressure or under reduced pressure, and the molecular weight can be adjusted by the charging ratio (excess ratio: the equivalent ratio of hydroxyl groups to acid groups) of the polybasic acid and / or its anhydride and the polyhydric alcohol. As a method for making it water-soluble, during the reaction of the above polybasic acid and / or its anhydride and the polyhydric alcohol, introduction of carboxyl groups by copolymerization with acrylic acid and methacrylic acid, introduction of sulfonic acid groups by metal salts such as sulfoterephthalic acid, 5-sulfophthalic acid, 4-sulfophthalic acid, 4-sulfonaphthalene-2,7-dicarboxylic acid-5[4-sulfophenoxy]isophthalic acid and ester-forming derivatives thereof, etc. can be exemplified. Examples of the metal salts include salts of Li, Na, K, Mg, Ca, Cu, Fe, etc. Particularly preferred are 5-sodium sulfophthalic acid and dimethyl-5-sodium sulfophthalic acid.

[0066] (Polybasic acid and / or its anhydride) As the polybasic acid and / or its anhydride that can be used in the synthesis of the aqueous polyester resin (C), dibasic acid and / or its anhydride is preferably used. Specifically, aromatic dibasic acids and their anhydrides such as terephthalic acid, isophthalic acid, phthalic anhydride, etc., alicyclic dibasic acids such as tetrahydrophthalic anhydride, hexahydrophthalic anhydride, 1,4-cyclohexanedicarboxylic acid, and their anhydrides, aliphatic dibasic acids such as (anhydrous) succinic acid, fumaric acid, (anhydrous) maleic acid, adipic acid, sebacic acid, azelaic acid, dimer acid, and their anhydrides can be mentioned. These can be appropriately selected and used from among them in consideration of the surface tension and surface free energy, flexibility, and adhesion of the obtained coating film.

[0067] (Polyhydric alcohol) In addition, examples of the above polyhydric alcohol include ethylene glycol, diethylene glycol, 1,4-butanediol, neopentyl glycol, trimethylolpropane, octanediol, 2-n-butyl-2-ethyl-1,3-propanediol, 2,2-diethyl-1,3-propanediol, 2,2,4-trimethyl-1,3-pentanediol, 2-ethyl-1,3-hexanediol, etc. These can be appropriately selected and used from among them in consideration of the surface tension and surface free energy, flexibility, and adhesion of the obtained coating film.

[0068] The above aqueous polyester resin (C) is preferably used in the preparation of the aqueous primer composition of the present invention in the form of a solution dissolved in a solvent. As this solvent, those that can dilute the polyester resin and are water and / or hydrophilic organic solvents can be preferably used. For example, alcohols such as methanol, ethanol, propanol, and butanol; glycol ethers such as ethylene glycol (mono, di) methyl ether, ethylene glycol (mono, di) ethyl ether, ethylene glycol monobutyl ether, diethylene glycol (mono, di) methyl ether, diethylene glycol (mono, di) ethyl ether, diethylene glycol monoisopropyl ether, diethylene glycol monobutyl ether, triethylene glycol (mono, di) methyl ether, propylene glycol (mono, di) methyl ether, and dipropylene glycol (mono, di) methyl ether, etc. can be mentioned.

[0069] The acid value of the aqueous polyester resin (C) is preferably 80 KOHmg / g or less, more preferably 60 KOHmg / g or less, and even more preferably 40 KOHmg / g or less. By being within the above range, the hydrolysis of the polyester is suppressed, and the molecular weight can be maintained high, so that the cohesion of the coating film is improved, and the abrasion resistance becomes good. Since the acid value can be variously changed according to the types of polyester polyol and tetracarboxylic dianhydride used, those skilled in the art can easily select the types of polyester polyol and tetracarboxylic dianhydride to be within the above preferred range.

[0070] The range of the weight average molecular weight of the above aqueous polyester resin (C) is preferably about 3000 to 40000, and more preferably 10000 to 30000. When the weight average molecular weight is 3000 or more, the abrasion resistance of the coating film is good, and when the weight average molecular weight is 40000 or less, the fluidity is good and the printing suitability is improved.

[0071] Specific examples of the aqueous polyester resin (C) include Plascoat Z-446, Z-561, Z-565, Z-880, Z-3310, RZ-105, RZ-570, Z-730, Z-760 (manufactured by Gohsei Chemical Co., Ltd.), Aron Melt PES-2155A30, 2255A30, 2500A30, 2655A30, 2405A30, 2353A25 (manufactured by Toagosei Co., Ltd.), and the like.

[0072] The glass transition temperature (Tg) of the above binder resin is preferably -20 to 100 °C. This is because the abrasion resistance and flexural resistance are improved. More preferably, it is -10 to 90 °C, and even more preferably 0 to 80 °C. Here, the glass transition temperature (Tg) refers to the value measured based on JIS K0129. The measured value by differential scanning calorimetry (DSC) can be adopted, and the measuring instrument can be DSC8231 manufactured by Rigaku Corporation.

[0073] <Extender pigment> The aqueous primer composition of the present invention contains an extender pigment. By containing an extender pigment, it becomes possible to adjust the rheology to a viscosity range suitable for flexo and gravure printing, and it also becomes possible to adjust the surface tension of the aqueous primer composition and the surface free energy of the primer layer formed from the aqueous primer composition. Examples of the extender pigment used in the present invention include silica, calcium carbonate, barium sulfate, talc, magnesium carbonate, barium carbonate, calcium sulfate, kaolin, mica, muscovite, calcium silicate, aluminum silicate, etc. Among them, from the viewpoint of rheology control such as viscosity, at least one selected from the group consisting of silica, calcium carbonate, barium sulfate, and talc is preferable, and silica is particularly preferable. This is because silica has silanol groups on its surface, so the surface free energy is high, and the surface free energy of the primer layer itself becomes high. The extender pigment may be used alone or in combination of two or more.

[0074] When using silica as an extender pigment, silica in which the silanol groups on the silica surface are modified and hydrophobized with an organosilicon compound (hydrophobic silica) may be used. The DBA value indicating the degree of hydrophobization of the hydrophobic silica is preferably from 5 to 200, more preferably from 20 to 175. Being within this range promotes the interaction with the dispersion resin, facilitates rheology adjustment, and also facilitates adjustment to lower the surface tension. Note that the lower the DBA value, the more the silanol groups are modified with the organosilicon compound, meaning a higher degree of hydrophobization.

[0075] The content of the extender pigment in the aqueous primer composition is preferably in the range of 1 to 15% by mass, more preferably 2 to 12% by mass, and even more preferably 3 to 10% by mass. When it is 1% by mass or more, it becomes possible to reduce the gloss value (impart a matte feeling), and the surface free energy of the primer layer becomes high. Further, since the extender pigment is exposed on the surface, the build-up and leveling of the active energy ray-curable composition are good due to the unevenness. When it is 15% by mass or less, the fluidity and the smoothness of the surface are improved, and the abrasion resistance becomes good. Further, when it is within the above range, the transfer, build-up, and leveling of the aqueous primer composition on the paper substrate and / or the ink layer, and the transfer, build-up, and leveling of the active energy curable composition on the primer layer can be made compatible, so that the substrate adhesion and the interlayer adhesion as a laminate are improved and the abrasion resistance becomes good.

[0076] The average particle diameter of the extender pigment is preferably in the range of 1 to 10 μm, more preferably 2 to 8 μm, and even more preferably 2 to 5 μm. When the average particle diameter is 1 μm or more, the leveling property of the active energy ray-curable composition on the aqueous primer is improved, and when it is 10 μm or less, the abrasion resistance is good and a good matte feeling is obtained. Further, extender pigments having different average particle diameters may be used in combination for the purpose of adjusting the flow characteristics and controlling the size of the surface unevenness. Note that the above average particle diameter refers to the volume average particle diameter measured by the laser diffraction method, and can be measured using, for example, Microtrac Bell's T330EXII.

[0077] When silica is used as the extender pigment, the average particle size is preferably in the range of 1 to 10 μm, more preferably 2 to 8 μm, and even more preferably 2 to 5 μm.

[0078] The specific surface area m 2 / g of the above extender pigment by the BET method is preferably 50 to 500 m 2 / g, more preferably 100 to 400 m 2 / g, and even more preferably 100 to 350 m 2 / g. A matting effect is good when it is 50 m 2 / g or more, and the fluidity of the primer composition can be maintained when it is 500 m 2 / g or less, resulting in good leveling.

[0079] When silica is used as the extender pigment, the specific surface area m 2 / g by the BET method is preferably 50 to 500 m 2 / g, more preferably 100 to 400 m 2 / g, and even more preferably 100 to 350 m 2 / g.

[0080] Specific examples of silica include Mizukasil P-705, P-707, P-709, P-78A, P-78D, P-78F, P-73, P-50 (manufactured by Mizusawa Chemical Industry Co., Ltd.), Nipsil E-74P, E75, E-743, E-150J, E-1030, E-200, E-170, E-220, E-200A, E-1009, E-220A, E-1011, N-300A, K-500, HD-2, L-250, G-300 (manufactured by Tosoh Silica Corporation), Silicia 250, 250N, 256, 256N, 310P, 320, 350, 370, 380, 420, 430, 440, 450, 436, 446, 456, 530, 550, C-1504, C-1510, Silohobic 100, 200, 702, 704, 4004, 507, 505, 603 (manufactured by Fuji Silysia Chemical Ltd.), etc.

[0081] <Aqueous solvent> The present invention includes an aqueous solvent. As the aqueous solvent, water and / or a hydrophilic organic solvent are preferred. The aqueous solvent is preferably contained in an amount of 30 to 85% by mass, more preferably 40 to 80% by mass, and particularly preferably 50 to 75% by mass based on the total mass of the aqueous primer composition.

[0082] <hydrophilic organic solvent> The present invention preferably includes a hydrophilic organic solvent. The hydrophilic organic solvent is not particularly limited as long as it is soluble in water, and may be used alone or in combination of two or more. The hydrophilic organic solvent refers to those having a hydrophilic group such as an ether group or a hydroxyl group. The boiling point of the hydrophilic organic solvent is preferably 60 to 100°C, more preferably 70 to 90°C. By including a hydrophilic organic solvent having a boiling point of 60°C or higher, the surface tension is reduced, so the leveling of the aqueous primer composition in the paper substrate and the ink layer is improved. When the boiling point is 100°C or lower, there is almost no residual hydrophilic organic solvent in the coating film due to the drying process, so the surface free energy of the primer layer itself is not lowered. Therefore, the build-up and leveling of the active energy ray-curable composition are improved, and a good matte feeling can be obtained.

[0083] As the hydrophilic organic solvent, it is preferable to use an alcohol-based organic solvent or an ether-based organic solvent. Examples of the alcohol-based organic solvent include methanol, ethanol, isopropyl alcohol, 2-butanol, diacetone alcohol, allyl alcohol, 2-methyl-2-propanol, etc. Among them, it is preferable to use ethanol, methanol, isopropyl alcohol, and 2-butanol. Examples of the ether-based organic solvent include n-propyl ether, ethylene glycol dimethyl ether, etc. Among them, it is preferable to use n-propyl ether.

[0084] The hydrophilic organic solvent is preferably contained in an amount of 1 to 15% by mass, more preferably 2 to 10% by mass, based on the total mass of the aqueous primer composition. This is because the leveling of the aqueous primer composition on the paper substrate and / or the ink layer is improved due to the decrease in surface tension. In addition, since almost no residual solvent remains in the coating film after sufficient drying of the hydrophilic organic solvent, the surface free energy of the primer layer itself is not lowered, the build-up and leveling of the active energy ray-curable composition are improved, and a good matte feeling is obtained.

[0085] (Hardener) In the present invention, a polyisocyanate type hardener can be appropriately blended as needed within a range that does not inhibit the object of the present invention.

[0086] (Additive) In the present invention, additives such as a surface conditioner, a leveling agent, a wetting and penetrating agent, a thickener, an anti-skinning agent, an ultraviolet absorber, an antioxidant, a crosslinking agent, a preservative, a fungicide, a viscosity modifier, and a pH modifier can be appropriately blended as needed within a range that does not inhibit the object of the present invention.

[0087] (Surface conditioner) In addition, in order to make the surface tension of the aqueous primer composition of the present invention fall within a preferable range, a surface conditioner can be blended within a range that does not inhibit the object of the present invention. Specific examples of the surface conditioner include anionic surface conditioners such as dialkyl sulfosuccinates, alkylnaphthalene sulfonates, and fatty acid salts; nonionic surface conditioners such as polyoxyethylene alkyl ethers, polyoxyethylene alkyl allyl ethers, acetylene glycols, polyoxyethylene-polyoxypropylene block copolymers, acetylene glycols, and ethylene oxide-added acetylene glycols; cationic surface conditioners such as alkylamine salts and quaternary ammonium salts; silicone-based surface conditioners; and fluorine-based surface conditioners. Among them, nonionic surface conditioners such as acetylene glycols and ethylene oxide-added acetylene glycols are preferable. The HLB (Hydrophile-Lipophile Balance) value of the surface conditioner is not particularly limited as long as the aqueous primer composition has a desired surface tension, but is preferably 2 to 15, more preferably 3 to 10, and even more preferably 4 to 9. The surface conditioner may be used alone or in combination of two or more.

[0088] In addition, the content of the surface conditioner contained in the aqueous primer of the present invention is appropriately selected according to the purpose of use, but generally, it is preferably 0.01 to 10% by mass, and more preferably 0.5 to 8% by mass, based on the total mass of the aqueous primer composition. By adjusting the addition amount of the surface conditioner as needed within the above range, the surface tension of the aqueous primer composition can be adjusted.

[0089] (Leveling agent) In the above aqueous primer layer, a leveling agent can be blended for the purpose of adjusting surface characteristics (such as surface free energy) and improving coatability. For example, known leveling agents such as fluorine-based, acrylic-based, siloxane-based, and their adducts or mixtures can be used. The blending amount is appropriately determined according to, for example, the adjustment of surface characteristics and coatability.

[0090] (Viscosity of the primer composition) In the present invention, the viscosity of the aqueous primer composition is preferably 50 to 2500 mPa·s, more preferably 100 to 1500 mPa·s. When it is 50 Pa·s or more, the transferability of the aqueous primer composition to the paper substrate becomes good, and when it is 2500 Pa·s or less, the leveling property after sticking becomes good. Also, the viscosity referred to here is the measured value by the method described in JIS K5600-2. For example, it can be measured at a shear rate of 100 per second in a 25°C environment using a cone-plate viscometer with a cone having a cone diameter of 35 mm and a cone angle of 1°.

[0091] In the present invention, in order to make the viscosity of the aqueous primer within a preferable range, the content of the extender pigment in the aqueous primer is preferably in the range of 1 to 15% by mass, more preferably 2 to 10% by mass, and even more preferably 3 to 8% by mass. The content of the hydrophilic organic solvent in the aqueous primer is preferably contained in an amount of 1 to 15% by mass, still more preferably contained in an amount of 2 to 10% by mass. The ratio of the binder resin in the aqueous primer is 10 to 50% by mass, more preferably 20 to 40% by mass.

[0092] (Thickener) In order to make the viscosity of the above aqueous primer composition within a preferable range, a thickener can be contained within the range where the effects of the present invention are exhibited. By containing a thickener in the primer composition, it can be easily adjusted to a viscosity according to the coating method. Examples of such thickeners include urethane-based thickeners and polyethylene oxide-based thickeners. Specific examples of urethane-based thickeners include Adeka Noalcol UH-756VF, UH-752, UH-472 manufactured by Adeka Corporation, Disparon AQ-580, AQ-600, AQ-607 manufactured by Kusumoto Chemical Co., Ltd., BYK-420 manufactured by BYK Co., etc. Specific examples of polyethylene oxide-based thickeners include PEO-1, PEO-2, PEO-3 manufactured by Sumitomo Seika Chemicals Co., Ltd., Polyox N-80, N-750 manufactured by Union Carbide Corporation, etc. These may be used alone or in combination of two or more.

[0093] The content of the thickener is preferably 0.1 to 10.0% by mass, more preferably 0.3 to 8.0% by mass, and particularly preferably 0.5 to 5.0% by mass in the total mass of the aqueous primer composition. When the content of the thickener is 0.1% by mass or more, the viscosity of the primer composition does not become too low, the extender pigment in the system is less likely to settle, and the storage stability is improved. Also, when the content of the thickener is 10.0% by mass or less, the viscosity of the primer composition does not become too high, and unevenness in thickness due to coating unevenness or poor leveling is less likely to occur. When a water-soluble thickener is used, the content of the thickener refers to the content in terms of solid content in the thickener.

[0094] <Manufacture of Aqueous Primer> As a method for manufacturing the aqueous primer of the present invention, there are a method of mixing a binder resin, an extender pigment, an aqueous solvent, and further, if necessary, a pigment, a curing agent, additives, etc. in necessary amounts and stirring well with a stirrer or the like, or a method of dispersing using a sand mill or the like.

[0095] <Active Energy Ray Curing Layer> The active energy ray curing layer of the present invention is formed by printing an active energy ray curable composition on the primer layer and then irradiating with active energy rays. The 60-degree specular glossiness of the active energy ray curing layer is preferably 40 or less, and it has excellent matting properties. More preferably, it is 18 or less, and still more preferably 11 or less. The gloss value is measured using a Microtrigloss made by BYK at an incident angle of 60°.

[0096] <Active Energy Ray Curable Composition> The active energy ray composition of the present invention is not particularly limited as long as it contains a compound that cures by active energy rays. However, from the viewpoints of abrasion resistance and matting properties, it preferably contains resin fine particles. Also, as a preferable composition of the active energy ray curable composition, those containing a polyfunctional urethane acrylate, a monofunctional ethylenically unsaturated monomer, a bifunctional ethylenically unsaturated monomer, resin fine particles, and a photopolymerization initiator can be exemplified.

[0097] <Manufacture of Active Energy Ray Curable Composition> As a method for producing an active energy ray-curable composition, it can be produced by stirring a polyfunctional urethane acrylate, a monofunctional ethylenically unsaturated monomer, a difunctional ethylenically unsaturated monomer, resin fine particles, and a photopolymerization initiator with a stirrer with blades (disper) for about 30 minutes to 3 hours. When it is difficult to mix and the viscosity and the like tend to be non-uniform, a roller mill, a ball mill, a pebble mill, an attritor, a sand mill, etc. may be used.

[0098] <Resin fine particles> In the present invention, the resin fine particles bear the functions of abrasion resistance and matting properties. As the resin fine particles, the average particle diameter is preferably 1 to 10 μm, more preferably 1.5 to 8 μm, still more preferably 2 to 6 μm, and particularly preferably 2 to 3 μm. The average particle diameter referred to here means the volume average particle diameter by the laser diffraction method, and can be measured using, for example, T330EXII manufactured by Microtrac Bell Co., Ltd. The resin fine particles are preferably contained in an amount of 5 to 40% by mass, more preferably 10 to 35% by mass, and still more preferably 20 to 30% by mass in the total mass of the active energy ray-curable composition.

[0099] Preferable specific examples of the resin fine particles include, for example, urethane resin fine particles, silicone resin fine particles, melamine resin fine particles, melamine-benzoguanamine resin fine particles, acrylic resin fine particles (for example, polymethyl methacrylate resin fine particles), acrylic-styrene copolymer resin fine particles, polycarbonate resin fine particles, polyethylene resin fine particles, polystyrene resin fine particles, benzoguanamine resin fine particles, and the like. These may be used alone or in combination of two or more. Among them, urethane resin fine particles are more preferable. The above resin fine particles may be used in combination of two or more as necessary.

[0100] Specific examples of urethane resin fine particles include, for example, crosslinked urethane beads such as Art Pearl C-1000 transparent, Art Pearl C-600 transparent, Art Pearl C-400 transparent, Art Pearl C-800, Art Pearl MM-120T, Art Pearl JB-800T, Art Pearl JB-600T, Art Pearl P-800T, Art Pearl P-400T (manufactured by Negami Kogyo Co., Ltd.).

[0101] Specific examples of silicone resin fine particles include KMP-594, KMP-597, KMP-598, KMP-600, KMP-601, KMP-602 (manufactured by Shin-Etsu Chemical Co., Ltd.), Trefil E-506S, EP-9215 (manufactured by Toray Dow Corning Co., Ltd.), etc.

[0102] Specific examples of melamine resin fine particles include Epotar SS, Epotar S, Epotar FS, Epotar S6, Epotar S12 (manufactured by Nippon Shokubai Co., Ltd.), etc. Specific examples of melamine-benzoguanamine resin fine particles include Epotar M30 (manufactured by Nippon Shokubai Co., Ltd.).

[0103] Specific examples of acrylic resin fine particles include Epotar MA1002, Epotar MA1004, Epotar MA1006, Epotar MA1010 (manufactured by Nippon Shokubai Co., Ltd.), Toughick FH-S005, Toughick FH-S008, Toughick FH-S010, Toughick FH-S015, Toughick FH-S020 (manufactured by Toyobo Co., Ltd.), Chemisnow M X-80H3wT, MX-150, MX-180TA, MX-300, MX-500, MX-1000, MX-1500H, MX-2000, MX-3000 (manufactured by Soken Chemical & Engineering Co., Ltd.), etc.

[0104] Specific examples of acrylic-styrene copolymer resin fine particles include Epotar MA2003 (manufactured by Nippon Shokubai Co., Ltd.), FS-102, FS-201, FS-301, MG-451, MG-351 (manufactured by Nippon Paint Industrial Coatings Co., Ltd.), etc.

[0105] Specific examples of the polycarbonate resin fine particles include the fine particles described in JP-A-2014-125495, the fine particles obtained by the production method described in JP-A-2011-26471, and the fine particles obtained by the method described in JP-A-2001-213970, etc.

[0106] Specific examples of the polyethylene resin fine particles include Miporon XM-220, XM221U (manufactured by Mitsui Chemicals, Inc.), Flow Beads LE-1080 (manufactured by Sumitomo Seika Chemicals Co., Ltd.), etc.

[0107] Specific examples of the polystyrene-based fine particles include Chemisnow SX-130H, SX-350H, SX-500H (manufactured by Soken Chemical & Engineering Co., Ltd.), etc.

[0108] Specific examples of the benzoguanamine resin fine particles include Epotar MS, Epotar M05, Epotar L15 (manufactured by Nippon Shokubai Co., Ltd.), etc.

[0109] <Paper substrate> The paper substrate used in the present invention is not particularly limited, and ordinary paper, cardboard, etc. are preferable. Although there is no particular specification for the film thickness, those having a thickness of 0.2 mm to 1.0 mm can be preferably used, and the printing surface may be corona-treated. Further, for the purpose of imparting design properties, the surface of the paper substrate may be vapor-deposited with a metal such as aluminum, and further surface treatment such as corona treatment may be performed. For example, coated paper, Mary coated paper, etc. are preferably mentioned.

[0110] <Printing ink composition> The above printing ink composition may be, for example, a known offset ink composition, an ultraviolet curable offset ink, a gravure ink composition, a flexo ink composition, an ultraviolet curable flexo ink composition, or other ink compositions, and any printing ink composition may be used. Among them, offset ink compositions and ultraviolet curable offset inks are suitable because they have a wide color gamut and it is easy to increase the printing density, so that a printing ink layer with high color reproducibility and designability can be formed. The printing ink composition may be an organic solvent-based, solvent-free, or aqueous composition.

[0111] <Printing of the printing ink layer> As a printing method of the printing ink composition, a known method can be used. For example, an offset printing method, a flexo printing method, a gravure printing method, a screen printing method, etc. may be mentioned, and the offset printing method is preferred. The thickness of the ink layer is preferably 0.1 to 15 μm, and more preferably 0.5 to 12 μm. Also, the above printing ink compositions may be combined to form an ink layer, and the printing layer can be formed by drying or ultraviolet curing after printing.

[0112] <Printing of the aqueous primer layer> In the present invention, it is preferable to form a primer layer using the aqueous primer of the present invention on the substrate by printing. As a printing method for printing the aqueous primer on the substrate, a known method can be used, and flexo printing and gravure printing are preferred.

[0113] <Manufacture of the laminate> The method for manufacturing the laminate of the present invention can be exemplified by a method in which an aqueous primer composition is formed into a primer layer on a paper substrate by flexographic or gravure printing, and further, after printing an active energy ray-curable composition on the primer layer, the active energy ray-curable layer is formed by irradiating the active energy ray. Further, after forming a printing layer composed of a printing ink composition on a paper substrate by a known printing method, an aqueous primer composition is formed into a primer layer by flexographic or gravure printing, and further, after printing an active energy ray-curable composition on the primer layer, the active energy ray-curable layer is formed by irradiating the active energy ray.

[0114] In addition, the printing and coating method of the active energy ray-curable composition is not particularly limited, and examples thereof include wet coating methods such as spray, shower, dipping, flow coating, gravure printing, flexographic printing, roll, spin, dispenser, inkjet printing, screen printing, etc. Among them, gravure printing and flexographic printing are preferred.

[0115] Examples of the active energy ray include ultraviolet rays such as far ultraviolet rays, ultraviolet rays, and near ultraviolet rays. On the other hand, it is also possible to use an electron beam or a proton beam. In this case, it can be cured without using a photoinitiator, but the effect of ultraviolet irradiation is preferred in terms of curing speed, availability of irradiation equipment, price, etc.

[0116] As a method of curing by ultraviolet irradiation, a high-pressure mercury lamp, an ultra-high-pressure mercury lamp, a carbon arc lamp, a metal halide lamp, a xenon lamp, a chemical lamp, an electrodeless discharge lamp, an LED, etc. that emit light in the wavelength range of 150 to 450 nm are used, and the integrated light amount is 30 to 5000 mJ / cm 2 , preferably 100 to 1000 mJ / cm 2 It may be irradiated. After ultraviolet irradiation, heating can be performed as necessary to complete the curing.

Example

[0117] Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited to the following examples. In the present invention, unless otherwise specified, "parts" represents "parts by mass" and "%" represents "% by mass".

[0118] (Surface tension) The surface tension refers to the surface tension measured by the Wilhelmy method, and was measured by, for example, a high-precision surface tensiometer DY-700 (manufactured by Kyowa Interface Science Co., Ltd.). The liquid temperature during measurement was 25°C.

[0119] (Surface free energy) The surface free energy was measured using a fully automatic contact angle meter DM-701 manufactured by Kyowa Interface Science Co., Ltd. 1 μL of water (pure water) was dropped onto the primer layer surface, and the contact angle after 30 seconds was measured. Further, 1 μL of n-hexadecane was dropped onto the primer layer surface and measured after 30 seconds. The value was calculated by the Kaelble-Uy method using the obtained contact angle of water and the contact angle of n-hexadecane.

[0120] (Average particle diameter) The average particle diameter refers to the volume average particle diameter measured by the laser diffraction method, and was measured using a Microtrac·Bell T330EXII.

[0121] (Viscosity) The viscosity was measured by the method described in JIS K5600-2, using a cone plate viscometer with a cone having a cone diameter of 35 mm and a cone angle of 1°, and was measured at a shear rate of 100 per second in a 25°C environment.

[0122] (Glass transition temperature) The glass transition temperature (Tg) was determined according to the method described in JIS K0129. Specifically, it was determined by DSC (differential scanning calorimetry). The measuring instrument used was DSC8231 manufactured by Rigaku Corporation. The measuring temperature range was -70 to 150°C, the heating rate was 10°C / min, and the midpoint between the end temperature and the endothermic start temperature based on the glass transition in the DSC curve was taken as the glass transition temperature.

[0123] (Production Example 1: Preparation of Active Energy Ray-Curable Composition U1) 12 parts of urethane acrylate (Beam Set 550B, manufactured by Arakawa Chemical Industries, Ltd.), 47 parts of 4-HBA (4-hydroxybutyl acrylate, manufactured by Osaka Organic Chemical Industry Co., Ltd.), 25 parts of ART-PEARL MM120T (urethane-based fine particles, average particle diameter 2 μm, glass transition temperature (Tg) 22 °C, manufactured by Negami Kogyo Co., Ltd.), 4 parts of Omnirad TPO (2,4,6-trimethylbenzoyldiphenylphosphine oxide, manufactured by IGM), which is a photopolymerization initiator, and 12 parts of a silicone-based defoaming agent as an additive were mixed and stirred with a blade stirrer for 90 minutes to obtain an active energy ray-curable composition U1.

[0124] (Production Example 2: Preparation of Active Energy Ray-Curable Composition U2) 10 parts of urethane acrylate (Beam Set 550B, manufactured by Arakawa Chemical Industries, Ltd.), 39 parts of 4-HBA (4-hydroxybutyl acrylate, manufactured by Osaka Organic Chemical Industry Co., Ltd.), 35 parts of ART-PEARL MM120T (urethane-based fine particles, average particle diameter 2 μm, glass transition temperature (Tg) 22 °C, manufactured by Negami Kogyo Co., Ltd.), 4 parts of Omnirad TPO (2,4,6-trimethylbenzoyldiphenylphosphine oxide, manufactured by IGM), which is a photopolymerization initiator, and 12 parts of a silicone-based defoaming agent as an additive were mixed and stirred with a blade stirrer for 90 minutes to obtain an active energy ray-curable composition U2.

[0125] (Production Example 3: Preparation of Active Energy Ray-Curable Composition U3) 21 parts of urethane acrylate (Beam Set 550B, manufactured by Arakawa Chemical Industries, Ltd.), 57 parts of 4-HBA (4-hydroxybutyl acrylate, manufactured by Osaka Organic Chemical Industry Co., Ltd.), 6 parts of ART-PEARL MM120T (urethane-based fine particles, average particle diameter 2 μm, glass transition temperature (Tg) 22 °C, manufactured by Negami Kogyo Co., Ltd.), 4 parts of Omnirad TPO (2,4,6-trimethylbenzoyldiphenylphosphine oxide, manufactured by IGM), which is a photopolymerization initiator, and 12 parts of a silicone-based defoaming agent as an additive were mixed and stirred with a blade stirrer for 90 minutes to obtain an active energy ray-curable composition U3.

[0126] (Example 1: Preparation of Aqueous Primer Composition S1) 80 parts of an aqueous acrylic emulsion (A1) (styrene-acrylic emulsion 1, Tg 25°C, solid content 40%), 5 parts of silica-1 (average particle size 3 μm, oil absorption 260 ml / 100 g), 5 parts of ethanol, 8 parts of water, 2 parts of a dispersant (BYK193) as an additive, and 2 parts of a surface conditioner (tegoformex 810; silicone-based) were mixed and stirred with a blade stirrer for 20 minutes to obtain an aqueous primer composition S1.

[0127] (Examples 2 - 20, Comparative Examples 1 - 2: Preparation of Aqueous Primer Compositions S2 - S20, T1 - T2) Except for changing the raw materials and formulations described in Tables 1 and 2, aqueous primers S2 - S20 and T1 - T2 were obtained in the same manner as in Example 1. In the tables, numerical values without unit markings represent parts, and blanks indicate no blending. The abbreviations in the tables are as follows, and the solvent for the binder resin is water. Water-soluble acrylic resin (A2): Tg 19°C, solid content 25% Aqueous urethane resin (B1): Tg 25°C, solid content 30% Polyester resin (C): Tg 20°C, solid content 25% Styrene-butadiene resin: Tg 26°C, solid content 43% Silica-2: Average particle size 0.5 μm Silica-3: Average particle size 6 μm, oil absorption 250 ml / 100 g Silica-4: Average particle size 12 μm, oil absorption 240 ml / 100 g Silica-5: Average particle size 3.9 μm, oil absorption 230 ml / 100 g, DBA value 50 Calcium carbonate: Average particle size 3 μm, oil absorption 20 ml / 100 g Precipitated barium sulfate: Average particle size 3 μm Clay: Average particle size 3 μm, oil absorption 51 ml / 100 g Methanol: Boiling point 64.7°C Isopropyl alcohol: Boiling point 82.3°C 2-Butanol: Boiling point 100°C

[0128]

Table 1

[0129]

Table 2

[0130] (Example 21: Production of laminate T1) First, on an Aurora Coat (coated paper, high gloss type, paper thickness 81 μm, manufactured by Nippon Paper Industries Co., Ltd.), which is a paper substrate, on the head side half in the printing direction of the paper substrate, "FD Carton X Ink M (manufactured by Toyo Ink Co., Ltd., containing a polyfunctional (meth)acrylic monomer with 3 or more functional groups)", which is a UV-curable offset ink, was printed so that the ink density was 1.75 (measuring instrument: X-Rite eXact (manufactured by X-Rite Inc.), conditions: illuminant D50, standard observer 2°, density status E, no filter), and cured with a UV lamp. As a result, a portion of only the paper substrate without an ink layer and a printed matter of the portion with an ink layer can be produced. Note that the printing speed of the above printing was 8000 sheets / hour, the types of UV lamps were 2 air-cooled metal halide lamps and 1 high-pressure mercury lamp, and the intensity of the UV lamps was 160 W / cm for all 3 lamps above (integrated light quantity 450 mJ / cm 2 ). Then, next, the aqueous primer S1 of Example 1 above was coated on the printed matter of FD Carton X Ink M obtained above using the flexo coating unit of a sheet-fed printing press "Lithrone 26 (manufactured by Komori Corporation)", and dried by a far-infrared and hot air dryer. As the anilox roll of the above coating unit, one with an engraved pattern of trihelical, line number of 80 line / inch, and cell volume of 15 ml / m 2 was used. Next, the active energy ray curable composition U1 obtained in Production Example 1 was applied onto the printed matter obtained above in the same manner as the aqueous primer composition, using a flexographic coating unit of a sheet-fed printing press "Lithrone 26 (manufactured by Komori Corporation)" and cured with a UV lamp to obtain a laminate T1. Note that the anilox roll of the coating unit had a trihelical engraved pattern, a line count of 90 lines / inch, and a cell volume of 25 ml / m. 2 During flexo coating, the printing speed was 8000 sheets / hour, and the temperature of the S1 liquid was controlled to 25°C. The type, number, and intensity of the UV lamps were the same as those used for the curing conditions of FD Karton X Ink M described above.

[0131] (Examples 22 to 42 and Comparative Examples 3 to 4: Preparation of Laminates L2 to L22 and M1 to 2) By a method similar to that of Example 21, laminates L2 to L22 and M1 to 2 were obtained using the aqueous primers S2 to S20 obtained in Examples 2 to 20 and the active energy ray curable compositions U2 and U3 obtained in Production Examples 2 and 3 under the composition conditions shown in Tables 3 and 4.

[0132] [Table 3]

[0133] [Table 4]

[0134] (evaluation) The following evaluations were carried out using the laminates for packaging materials having the aqueous primer compositions and the active energy ray-curable compositions obtained in the above Examples and Comparative Examples, and the evaluation results are shown in Tables 3 and 4.

[0135] <Anti-mottling> For the laminates obtained in the examples and comparative examples, the gloss values on the aqueous primer / active energy ray-curable layer on the ink layer of FD Carton X Ink M and on the aqueous primer / active energy ray-curable layer directly laminated on the paper substrate where the ink layer of FD Carton X Ink M was not printed were measured at 50 random locations each, and the relative standard deviation of the gloss value (the ratio of the variation to the average value of the gloss value) was evaluated. The larger the relative standard deviation, the higher the gloss unevenness and the poorer the printing appearance (mottling). The gloss value was measured at an incident angle of 60° using a Micro-TRIGLOSS manufactured by BYK. The evaluation criteria are as follows. 5 (excellent): less than 2% 4 (good): 2% or more and less than 3% 3 (fair): 3% or more and less than 5% 2 (poor): 5% or more and less than 10% 1 (inferior): 10% or more Note that the practically usable evaluations are 3, 4, and 5.

[0136] <Matte property> For the laminates obtained in the examples and comparative examples, the gloss value on the aqueous primer / active energy ray-curable layer directly laminated on the paper substrate where the ink layer of FD Carton X Ink M was not printed was measured. The gloss value was measured at an incident angle of 60° using a Micro-TRIGLOSS manufactured by BYK. The evaluation criteria are as follows. 5 (excellent): 11 or less 4 (good): greater than 11 and 18 or less in gloss value 3 (fair): greater than 18 and 40 or less in gloss value 2 (poor): greater than 40 and 50 or less in gloss value 1 (inferior): greater than 50 in gloss value Note that the practically usable evaluations are 3, 4, and 5.

[0137] <Scratch resistance> For the laminates obtained in the examples and comparative examples, set them on a Sutherland Rub Tester (manufactured by Toyo Seiki Seisakusho Co., Ltd.) so that the cured layers of the aqueous primer / active energy ray-curable layer on the ink layer of FD Carton X Ink M are in contact with each other. After applying a load of 2 pounds and reciprocating a predetermined number of times, the abrasion resistance was evaluated by visually checking whether the cured layer peeled off and the base layer was visible. The evaluation criteria are as follows. 5 (excellent): Even after 10,000 reciprocations, the cured layer did not peel off and the base layer was not visible. 4 (good): After 10,000 reciprocations, the cured layer peeled off and the base layer was visible, but after 9,000 reciprocations the base layer was not visible. 3 (fair): After 9,000 reciprocations, the cured layer peeled off and the base layer was visible, but after 8,000 reciprocations the base layer was not visible. 2 (poor): After 8,000 reciprocations, the cured layer peeled off and the base layer was visible, but after 7,000 reciprocations the base layer was not visible. 1 (inferior): Even after 7,000 reciprocations, the cured layer peeled off and the base layer was visible. Note that the practically usable evaluations are 3, 4, and 5.

[0138] According to the present invention, it has become possible to provide an aqueous primer composition excellent in mottling resistance (gloss unevenness) when an active energy ray-curable composition is applied on a primer layer, and a laminate for packaging materials excellent in cosmetic appearance (matting property) and abrasion resistance.

[0139] Comparative Examples 1 and 2 that do not contain extender pigments resulted in inferior mottling resistance and matting property.

Claims

1. An aqueous primer composition for forming a primer layer of a laminate for packaging materials, which sequentially has a paper substrate, a primer layer, and an active energy ray-curable layer, The aqueous primer composition contains a binder resin, an extender pigment, and an aqueous solvent.

2. The aqueous primer composition according to claim 1, having a surface tension of 24 to 38 mN / m.

3. The aqueous primer composition according to claim 1 or 2, wherein the surface free energy of the primer layer is 24 to 40 dyne / cm.

4. The aqueous primer composition according to claim 1 or 2, wherein the aqueous solvent contains a hydrophilic organic solvent.

5. The aqueous primer composition according to claim 1 or 2, having a viscosity of 50 to 2500 mPa·s.

6. The aqueous primer composition according to claim 1 or 2, wherein the binder resin contains at least one selected from the group consisting of an aqueous acrylic resin (A), an aqueous urethane resin (B), and an aqueous polyester resin (C).

7. The aqueous primer composition according to claim 1 or 2, wherein the extender pigment contains at least one selected from the group consisting of silica, calcium carbonate, barium sulfate, and talc.

8. The aqueous primer composition according to claim 1 or 2, wherein the average particle diameter of the extender pigment is 1 to 10 μm.

9. The aqueous primer composition according to claim 4, wherein the boiling point of the hydrophilic organic solvent is 70 to 90°C.

10. The aqueous primer composition according to claim 1 or 2, which is for flexographic or gravure printing.

11. A laminate for packaging materials, which sequentially has a paper substrate, a primer layer formed from the aqueous primer composition according to claim 1 or 2, and an active energy ray-curable layer, The laminate for packaging materials, wherein the active energy ray-curable layer contains resin fine particles.

12. The laminate for packaging materials according to claim 11, further having an offset printing layer.

13. The laminate for packaging materials according to claim 11, wherein the 60-degree specular glossiness of the active energy ray-curable layer is 40 or less.

14. A method for manufacturing a laminate for packaging materials, which sequentially has a paper substrate, a primer layer, and an active energy ray-curable layer, A method for manufacturing a laminate for packaging materials, comprising the steps of: forming the primer layer by flexographic or gravure printing an aqueous primer composition containing a binder resin, an extender pigment, and an aqueous solvent on a paper substrate; and forming the active energy ray-cured layer by irradiating active energy rays after printing an active energy ray-curable composition on the primer layer.

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