Aqueous white ink composition, laminate, and plastic labels

Abstract

To provide: an aqueous white ink composition capable of forming a printed layer with excellent resistance to lubricants for belt conveyors; a laminate having the printed layer; and labels, including food and beverage labels, obtained using the laminate.SOLUTION: An aqueous white ink composition comprises an aqueous binder resin, a water-repellent silicone, and titanium oxide. When the aqueous white ink composition is printed on a printing target by flexographic printing with a dry coating weight of 2 g / m2, the water contact angle on the surface of the resulting dried coating film is 90° or more.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a water-based white ink composition, a laminate, a label, and a label for food and beverages. [Background technology]

[0002] Plastic containers, metal containers, paper containers, etc. are used as packaging containers for beverages, foods such as prepared dishes and bento boxes, daily necessities such as cosmetics, etc. Plastic labels are often attached to these packaging containers. As plastic labels, roll labels that are wrapped around plastic containers and secured with adhesives, and heat-shrinkable films that can follow the shape of the packaging container by applying heat, etc. are used. Usually, on the back side (the side that contacts the packaging container) of these labels, a printed layer (hereinafter also referred to as a "color printed layer") formed using an ink composition containing a color pigment is provided for the purpose of imparting design, functionality, etc. Furthermore, a printed layer formed using a white ink composition may be laminated on the color printed layer for the purpose of protecting the color printed layer and imparting hiding properties.

[0003] Conventionally, organic solvent-based white ink compositions have been used as the white ink composition. However, in recent years, awareness of reducing environmental load and improving the working environment has increased, and there is a demand to switch from organic solvent-based white ink compositions to aqueous white ink compositions. On the other hand, many problems have been identified with the aqueous white ink composition.

[0004] For example, when a plastic label is attached to a packaging container for food and beverages (hereinafter also referred to as a "bottle"), the printed layer of the plastic label is required to be resistant to the belt conveyor lubricant used when the bottle is transported on a filling line. Specifically, when a plastic label is attached to a bottle having a belt conveyor lubricant adhering to its surface after transportation, or when a bottle with a plastic label attached is transported on a belt conveyor, the printed layer is required to be resistant to the belt conveyor lubricant.

[0005] The belt conveyor lubricant is an aqueous solution containing a surfactant. For example, Patent Document 1 discloses a lubricant composition for a bottle conveyor that contains a specific chelate compound, a nonionic surfactant, and water. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2007-197580 A Summary of the Invention [Problem to be solved by the invention]

[0007] Plastic labels having a printing layer formed using a conventional water-based white ink composition do not have sufficient resistance to belt conveyor lubricants. The present invention aims to provide an aqueous white ink composition capable of forming a printed layer having excellent resistance to belt conveyor lubricants, a laminate having said printed layer, and a label and a label for food and beverages obtained using said laminate. [Means for solving the problem]

[0008] The present invention has the following aspects. [1] A water-based white ink composition containing a water-based binder resin, a water-repellent silicone, and titanium oxide, the water-based white ink composition being applied to a printing object by flexographic printing in a coating amount of 2 g / m after drying. 2 The water-based white ink composition has a surface water contact angle of 90° or more when the ink is dried and formed by printing so as to form a coating film having a surface water contact angle of 90° or more. [2] The water-based white ink composition according to [1], wherein the content of the water-repellent silicone is 0.1 mass% or more relative to the total mass of the non-volatile matters of the water-based white ink composition. [3] The water-based white ink composition according to [1] above, wherein the water contact angle of the surface of the dried coating film is 90 to 110°. [4] The water-based white ink composition according to [3] above, wherein the content of the water-repellent silicone is 0.1 to 1.8 mass % relative to the total mass of the non-volatile matters of the water-based white ink composition. [5] The water-based white ink composition according to any one of [1] to [4] above, for use together with a curing agent. [6] The water-based white ink composition according to any one of the above [1] to [5], wherein the water-based binder resin contains an acrylic resin emulsion having a glass transition temperature of -20 to 100°C. [7] The water-based white ink composition according to any one of [1] to [6] above, wherein the water-based binder resin comprises an acrylic resin emulsion and a water-soluble acrylic resin. [8] The water-based white ink composition according to [7] above, wherein a blending ratio of the acrylic resin emulsion to the water-soluble acrylic resin is, in terms of mass ratio, acrylic resin emulsion:water-soluble acrylic resin=80:20 to 99:1. [9] A laminate comprising a plastic film and a printed layer formed on one surface of the plastic film using the water-based white ink composition according to any one of [1] to [8] above.

[10] A laminate comprising a plastic film, a first printed layer formed on one side of the plastic film using an aqueous ink composition containing a color pigment, and a second printed layer formed on the side of the first printed layer opposite the plastic film using any one of the aqueous white ink compositions [1] to [8].

[11] A label obtained by using the laminate according to [9].

[12] A label obtained by using the laminate according to

[10] .

[13] The laminate of [9] above, wherein the water-based white ink composition is an ink for food and beverage labels having excellent resistance to belt conveyor lubricants, and the laminate is for food and beverage labels obtained using the ink.

[14] The laminate of

[10] , wherein the water-based white ink composition is an ink for food and beverage labels having excellent resistance to belt conveyor lubricants, and the laminate is for food and beverage labels obtained using the ink.

[15] A label for food and beverages, obtained using the laminate according to

[13] .

[16] A label for food and beverages, obtained using the laminate according to

[14] . Effect of the Invention

[0009] According to the present invention, there can be provided an aqueous white ink composition capable of forming a printed layer having excellent resistance to belt conveyor lubricants, a laminate having said printed layer, and a label and a label for food and beverages obtained using said laminate. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a cross-sectional view illustrating a schematic example of a laminate of the present invention. [Diagram 2] FIG. 1 is a cross-sectional view illustrating a schematic example of a laminate of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] 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 aqueous white ink composition means that the composition contains water as a medium. "Water-based acrylic resin" is a general term for "water-soluble acrylic resin" and "water-dispersible acrylic resin (acrylic resin emulsion, acrylic resin dispersion)." The same applies to "water-based acrylic urethane resin," "water-based urethane resin," etc. "Non-volatile content" refers to the components contained in the water-based white ink composition excluding volatile media such as water and organic solvents, and is the component that will ultimately form the printed layer, and is specifically measured in accordance with JIS K 5601-1-2:2008. In this specification, "(meth)acrylate" is a general term for "acrylate" and "methacrylate". "(meth)acrylic acid" is a general term for "acrylic acid" and "methacrylic acid". "(meth)acryloyloxy group" is a general term for "acryloyloxy group" and "methacryloyloxy group". The weight average molecular weight of the aqueous binder resin is a weight average molecular weight converted into a standard polystyrene molecular weight and is measured by gel permeation chromatography (GPC). The glass transition temperature of the aqueous binder resin is measured in accordance with JIS K 7121:2012 as follows: A differential scanning calorimeter is used to measure the glass transition temperature from the intersection point between the baseline and the tangent of the endothermic curve in a curve (DSC curve) obtained by heating 10 mg of the aqueous binder resin from -100°C to 160°C at a temperature of 20°C / min. The acid value of the aqueous binder resin is 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 is measured in accordance with JIS K 5601-2-1:1999.

[0012] [Water-based white ink composition] The water-based white ink composition according to one embodiment of the present invention contains the water-based binder resin (A), water-repellent silicone (B), and titanium oxide (C) shown below. The water-based white ink composition may further contain components (optional components) other than the water-based binder resin (A), the water-repellent silicone (B), and the titanium oxide (C) as necessary, as long as the effects of the present invention are not impaired. For example, the water-based white ink composition typically further contains an aqueous medium (D).

[0013] <Water contact angle> The water-based white ink composition of the present embodiment is applied to a printing object by flexographic printing in a coating amount of 2 g / m after drying. 2 The surface of the dried coating film formed by printing so as to have a water contact angle of 90° or more.

[0014] The water contact angle of the surface of the dried coating film can be measured in accordance with JIS R 3257:1999. The formation of the dried coating film can be carried out, for example, as follows. The aqueous white ink composition is printed by flexographic printing on a substrate such as a plastic film, which is the printing target. In this case, when the coating amount after drying is 2 g / m 2 Printing is performed so that the ratio of the mass of the dry coating film to the area of ​​the printed surface of the printed object is (mass of the dry coating film / area of ​​the printed surface of the printed object). The mass of the dry coating film can be calculated from "mass of the substrate with the dry coating film after printing-mass of the substrate before printing". The mass of the dry coating film can also be calculated from "mass of the substrate with the dry coating film after printing-mass after removing the dry coating film from the substrate with the dry coating film after printing". As a method for removing the dry coating film from the substrate with the dry coating film after printing, a method of washing and wiping the dry coating film with an organic solvent such as isopropanol or methyl ethyl ketone can be mentioned. The substrate is, for example, a plastic film, and the plastic film described later can be used. The printed surface of the substrate is preferably smooth. The drying conditions are not particularly limited as long as the volatile content contained in the aqueous white ink composition can be removed, and examples of the drying methods include drying by leaving the substrate in a drying oven and drying with hot air from a dryer.

[0015] The water contact angle of the surface of the dried coating film is 90° or more, preferably 92° or more, more preferably 93° or more, and even more preferably 95° or more. The water contact angle of the surface of the dried coating film is preferably 110° or less, more preferably 107° or less, and even more preferably 105° or less. The above upper limit value and the above lower limit value of the water contact angle can be combined arbitrarily. When the water contact angle of the surface of the dried coating is equal to or greater than the lower limit, the resistance of the printed layer (hereinafter also referred to as "printed layer (W)") formed from the aqueous white ink composition of this embodiment to the lubricant for the belt conveyor is improved. That is, when the water contact angle of the surface of the dried coating is less than the lower limit, the resistance of the printed layer (W) to the lubricant for the belt conveyor is reduced. When the water contact angle of the surface of the dried coating is equal to or less than the upper limit, the lamination property is improved when the aqueous white ink composition of this embodiment or another ink composition or varnish composition is overcoated on the printed layer (W) to further laminate the printed layer. Here, "lamination property" means the performance of the printed layer further printed on the printed layer (W) being transferred onto the printed layer (W) without being repelled. Examples of the printed layer further printed on the printed layer (W) include a printed layer formed from the aqueous white ink composition of this embodiment or another ink composition, and a printed layer (varnish layer) formed from a varnish composition. In the following specification, "adjacent layer" means a layer further printed on the printed layer (W) of this embodiment. The water contact angle of the surface of the dried coating film can be adjusted by adjusting the composition of the water-based white ink composition, particularly by adjusting the type and content of the water-repellent silicone (B).

[0016] <Water-based binder resin (A)> Examples of the aqueous binder resin (A) include aqueous acrylic resin, aqueous acrylic urethane resin, aqueous urethane resin, aqueous polyester resin, aqueous polyamide resin, aqueous chloride-vinyl acetate copolymer resin, aqueous cellulose resin, aqueous epoxy resin, and aqueous olefin resin. From the viewpoint of further improving the adhesion of the printed layer (W) to the plastic film described later, aqueous acrylic resin, aqueous acrylic urethane resin, and aqueous urethane resin are preferred, aqueous acrylic resin and aqueous acrylic urethane resin are more preferred, acrylic resin emulsion, water-soluble acrylic resin, and acrylic urethane resin emulsion are even more preferred, and acrylic resin emulsion and water-soluble acrylic resin are particularly preferred. From the viewpoint of particularly excellent adhesion of the printed layer (W) to the OPP film when the printed layer (W) is formed on a biaxially oriented polypropylene (OPP) film (hereinafter also referred to as "OPP film"), the aqueous binder resin (A) preferably contains an acrylic resin emulsion. From the viewpoint of increasing the dispersibility of titanium oxide (C) in the aqueous white ink composition, the aqueous binder resin (A) preferably contains a water-soluble acrylic resin. The aqueous binder resin (A) more preferably contains an acrylic resin emulsion and a water-soluble acrylic resin. These aqueous binder resins (A) may be used alone or in combination of two or more.

[0017] (Water-based acrylic resin) A water-based acrylic resin is a resin that contains (meth)acrylate units. Examples of the aqueous acrylic resin include homopolymers of (meth)acrylates, copolymers of two or more kinds of (meth)acrylates, and copolymers of (meth)acrylates and monomers other than (meth)acrylates. The proportion of the (meth)acrylate unit to the total mass of all monomer units constituting the aqueous acrylic resin is preferably from 10 to 100% by mass, and more preferably from 20 to 100% by mass.

[0018] Examples of the (meth)acrylate 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. These (meth)acrylates may be used alone or in combination of two or more.

[0019] Examples of monomers other than (meth)acrylates 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; unsaturated carboxylic acids such as (meth)acrylic acid, itaconic acid, maleic acid, and fumaric acid; 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.

[0020] The weight-average molecular weight of the aqueous acrylic resin is preferably 1,000 to 1,150,000, more preferably 5,000 to 500,000, and from the viewpoint of achieving a particularly excellent balance of the solvent resistance, water resistance, blocking resistance, and adhesion to plastic films of the printed layer (W), is even more preferably 6,000 to 390,000. When the weight-average molecular weight of the aqueous acrylic resin is equal to or greater than the above lower limit, the solvent resistance and blocking resistance of the printed layer (W) are improved, and when it is equal to or less than the above upper limit, the adhesion of the printed layer (W) to plastic films is improved. In particular, the weight average molecular weight of the acrylic resin emulsion is preferably 5,000 to 1,150,000, more preferably 10,000 to 500,000, and from the viewpoint of achieving a particularly excellent balance of the solvent resistance, water resistance, blocking resistance, and adhesion to plastic films of the printed layer (W), it is even more preferably 20,000 to 390,000. The weight average molecular weight of the water-soluble acrylic resin is preferably 1,000 to 500,000, more preferably 3,000 to 200,000, and from the viewpoint of achieving a particularly excellent balance of pigment dispersibility, ink fluidity, ink resolubility, blocking resistance of the printing layer (W), and adhesion to plastic films, it is even more preferably 5,000 to 100,000.

[0021] The glass transition temperature of the aqueous acrylic resin is preferably −20 to 140° C., more preferably −10 to 100° C., and even more preferably −5 to 70° C., and from the viewpoint of achieving a particularly excellent balance between the blocking resistance of the printed layer (W) and its adhesion to plastic films, is particularly preferably 0 to 40° C. When the glass transition temperature of the aqueous acrylic resin is equal to or higher than the above lower limit, the blocking resistance of the printed layer (W) is improved, and when it is equal to or lower than the above upper limit, the adhesion of the printed layer (W) to plastic films is improved. In particular, the glass transition temperature of the acrylic resin emulsion is preferably -20 to 100°C, more preferably -15 to 90°C, even more preferably -10 to 80°C, particularly preferably 0 to 70°C, and most preferably 5 to 60°C from the viewpoint of achieving a particularly excellent balance between the blocking resistance of the printing layer (W) and its adhesion to the plastic film. The glass transition temperature of the water-soluble acrylic resin is preferably 0 to 140°C, more preferably 10 to 130°C, and even more preferably 20 to 120°C. From the viewpoint of achieving a particularly excellent balance between the blocking resistance of the printing layer (W) and the adhesion to the plastic film, a glass transition temperature of 50 to 110°C is particularly preferred.

[0022] The aqueous acrylic resin preferably has an acid value, preferably 1 to 300 mgKOH / g, more preferably 5 to 280 mgKOH / g, and even more preferably 10 to 250 mgKOH / g from the viewpoint of particularly excellent balance between adhesion of the printed layer (W) to the plastic film and ink stability when a curing agent is added. When the aqueous acrylic resin has an acid value, good water solubility is obtained. In addition, when a curing agent (E) described later is used in combination, a robust printed layer (W) can be obtained by crosslinking with the curing agent. In particular, the acid value of the acrylic resin emulsion is preferably 1 to 200 mgKOH / g, more preferably 5 to 150 mgKOH / g, and even more preferably 10 to 100 mgKOH / g from the viewpoint of achieving a particularly excellent balance between the adhesion of the printing layer (W) to the plastic film and the ink stability when a curing agent is added. The acid value of the water-soluble acrylic resin is preferably 10 to 300 mgKOH / g, more preferably 50 to 280 mgKOH / g, and even more preferably 80 to 260 mgKOH / g. From the viewpoint of achieving a particularly excellent balance between the adhesion of the printing layer (W) to the plastic film and the ink stability when a curing agent is added, the acid value is particularly preferably 100 to 250 mgKOH / g.

[0023] The aqueous acrylic resin can be obtained by polymerizing a monomer component containing a (meth)acrylate and, if necessary, a monomer other than the (meth)acrylate. The polymerization method is not particularly limited, but examples thereof include a method in which a monomer component is polymerized in the presence of a known radical polymerization initiator by a solution polymerization method, a bulk polymerization method, an emulsion polymerization method, or the like. The water-based acrylic resin may be self-crosslinking.

[0024] As the aqueous acrylic resin, commercially available products may be used. Examples of commercially available products include those under the trade names "Hi-Loss-X TE-1048", "Hi-Loss-X NE-2186", "Hi-Loss-X KE-1062", "Hi-Loss-X QE-1042", "Hi-Loss-X X-436", "Hi-Loss-X KE-1060", "Hi-Loss-X HE-2342", "Hi-Loss-X HE-1335", "Hi-Loss-X RE-1075", "Hi-Loss-X PE-1304", "Hi-Loss-X KE-2536", "Hi-Loss-X J-140A", "Hi-Loss-X TE-1102", "Hi-Loss-X RE-218", "Hi-Loss-X NE-2009", "Hi-Loss-X JE-1056", "Hi-Loss-X KE-1148", "Hi-Loss-X M-141", "Hi-Loss-X ME-2039", and "Hi-Loss-X UE-1051", "Hi-Los-X PE-1126", "Hi-Los-X JE-1113", "Hi-Los-X PL-1231", "Hi-Los-X BL-2300", "Hi-Los-X NL-1253", "Hi-Los-X X-228L", "Hi-Los-X M-30", "Hi-Los-X UL-1191", "Hi-Los-X YL-1098", "Hi-Los-X QL-1358", "Hi-Los-X YL-1825", "Hi-Los-X X-345", "Hi-Los-X GL-2439", "Hi-Los-X VL-1147", "Hi-Los-X X-321L", "Hi-Los-X AW-36H", "Hi-Los-X NL-1189"; trade names manufactured by AICA Corporation: "Ultrasol A-25", "Ultrasol A-35", "Ultrasol A-40", "Ultrasol A-50", "Ultrasol A-60", "Ultrasol A-70", "Ultrasol A-80", "Ultrasol A-90", "Ultrasol A-100", "Ultrasol A-120", "Ultrasol A-130", "Ultrasol A-200", "Ultrasol A-35", "Ultrasol A-40", "Ultrasol A-50", "Ultrasol A-130", "Ultrasol A-140", "Ultrasol A-150", "Ultrasol A-160", "Ultrasol A-170", "Ultrasol A-180", "Ultrasol A-190", "Ultrasol A-200", "Ultrasol A C-63", "Ultrasol C-70", "Ultrasol D-32", "Ultrasol D-40", "Ultrasol GP-300", "Ultrasol UL-1097";BASF Japan Ltd.'s product names are "Johncryl PDX-7357", "Johncryl PDX-7182", "Johncryl PDX-7326", "Johncryl PDX-7616A", "Johncryl PDX-7732", "Johncryl PDX-7741", "Johncryl PDX-7787", "Johncryl PDX-7356", "Johncryl PDX-7734", "Johncryl PDX-7777", "Johncryl PDX-7615", "Johncryl PDX-7775", "Johncryl PDX-7692", "Johncryl PDX-7630A", "Johncryl PDX-7158", "Johncryl 352D", "Johncryl PDX-7199", "Johncryl PDX-7358", "Johncryl PDX-7667", "Johncryl PDX-7700", and "Johncryl PDX-76 96", "Johncryl PDX-7780", "Johncryl PDX-7177", "Johncryl PDX-7164", "Johncryl PDX-7430", "Johncryl 67", "Johncryl 678", "Johncryl 611", "Johncryl 693", "Johncryl 682", "Johncryl 690", "Johncryl 819", "Johncryl JDX-C3000A", "Johncryl JDX-C3080", "Johncryl 52J", "Johncryl PDX-6157", "Johncryl 60J", "Johncryl 70J", "Johncryl JDX-6180", "Johncryl HPD-196", "Johncryl HPD-96J", "Johncryl PDX-6137A", "Johncryl 6610", "Johncryl JDX-6500", "Johncryl PDX-6102B" and others.; These aqueous acrylic resins may be used alone or in combination of two or more.

[0025] (Water-based acrylic urethane resin) Examples of the aqueous acrylic urethane resin include a reaction product of a polyisocyanate compound, a polyol compound, and a hydroxy group-containing (meth)acrylate, or a reaction product of a polyisocyanate compound and a hydroxy group-containing (meth)acrylate.

[0026] Examples of the polyisocyanate compound include aliphatic, alicyclic, aromatic, etc. Specific examples of the polyisocyanate compound include aliphatic diisocyanates such as trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, pentamethylene diisocyanate, 1,2-propylene diisocyanate, 1,2-butylene diisocyanate, 2,3-butylene diisocyanate, 1,3-butylene diisocyanate, 2,4,4- or 2,2,4-trimethylhexamethylene diisocyanate, and 2,6-diisocyanate methyl caproate; Diphenylmethane diisocyanate, isophorone diisocyanate, norbornene diisocyanate, 1,3-cyclopentane diisocyanate, 1,4-cyclohexane diisocyanate, 1,3-cyclohexane diisocyanate, 3-isocyanate methyl-3,5,5-trimethylcyclohexyl isocyanate (isophorone diisocyanate), 4,4'-methylenebis(cyclohexyl isocyanate), methyl-2,4-cyclohexane diisocyanate, methyl-2,6-cyclohexyl Alicyclic diisocyanates such as 1,4-bis(isocyanatemethyl)cyclohexane, 1,3-bis(isocyanatemethyl)cyclohexane; m-phenylene diisocyanate, p-phenylene diisocyanate, 4,4'-diphenyl diisocyanate, 1,5-naphthalene diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,4- or 2,6-tolylene diisocyanate, 4,4'-toluidine diisocyanate, dianisidine diisocyanate, 4, Examples of the diisocyanates include aromatic diisocyanates such as 4'-diphenyl ether diisocyanate; polyisocyanate compounds obtained by polymerizing the above diisocyanates and having an allophanate structure, a nurate structure, a biuret structure, or the like; triisocyanates such as 1,3,5-triisocyanate benzene, 2,4,6-triisocyanate toluene, and 1,3,5-triisocyanate hexane; and polyisocyanates such as 4,4'-diphenyl dimethyl methane-2,2'-5,5'-tetraisocyanate. These polyisocyanate compounds may be used alone or in combination of two or more.

[0027] Examples of the polyol compound include polyether polyols obtained by polymerizing oxirane compounds such as ethylene oxide, propylene oxide, butylene oxide, and tetrahydrofuran using low molecular weight polyols such as ethylene glycol, propylene glycol, trimethylolpropane, and glycerin as an initiator; ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, 1,2-propanediol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, pentanediol, 3-methyl-1,5-pentanediol, octanediol, 1,9-nonanediol, 1,8-nonanediol, 1,4-cyclohexanediol, 1,4 polyester polyols obtained by dehydration condensation of saturated or unsaturated glycols, such as cyclohexanedimethanol, bisphenol A, and hydrogenated bisphenol A, with dibasic acids, such as adipic acid, maleic acid, fumaric acid, phthalic anhydride, isophthalic acid, terephthalic acid, succinic acid, oxalic acid, malonic acid, glutaric acid, pimelic acid, azelaic acid, sebacic acid, and suberic acid, or with the corresponding acid anhydrides or dimer acids; polyolefin polyols, such as polyethylene polyols and polypropylene polyols; polyether ester polyols obtained by reacting the above dibasic acids or their dialkyl esters with the above polyether polyols; and polycarbonate polyols obtained by reacting the above glycols with methyl carbonate, diphenyl carbonate, ethylene carbonate, phosgene, or the like. These polyol compounds may be used alone or in combination of two or more.

[0028] Examples of the hydroxyl group-containing (meth)acrylate include the hydroxyalkyl (meth)acrylates exemplified above in the explanation of the water-based acrylic resin. Furthermore, as the aqueous acrylic urethane resin, for example, a core-shell type resin having an acrylic resin in the core portion and a urethane resin in the shell portion may be used.

[0029] The weight average molecular weight of the aqueous acrylic urethane resin is preferably 5000 to 120000, more preferably 10000 to 100000, and from the viewpoint of achieving a particularly excellent balance of the solvent resistance, water resistance, blocking resistance, and adhesion to plastic films of the printed layer (W), is even more preferably 10000 to 80000. When the weight average molecular weight of the aqueous acrylic urethane resin is equal to or more than the above lower limit, the solvent resistance and blocking resistance of the printed layer (W) are improved, and when it is equal to or less than the above upper limit, the adhesion of the printed layer (W) to plastic films is improved.

[0030] The glass transition temperature of the aqueous acrylic urethane resin is preferably −30 to 100° C., more preferably −30 to 90° C., and from the viewpoint of achieving a particularly excellent balance between the blocking resistance of the printed layer (W) and its adhesion to plastic films, further preferably −20 to 90° C. When the glass transition temperature of the aqueous acrylic urethane resin is equal to or higher than the above lower limit, the blocking resistance of the printed layer (W) is improved, and when the glass transition temperature is equal to or lower than the above upper limit, the adhesion of the printed layer (W) to plastic films is improved.

[0031] The aqueous acrylic urethane resin preferably has an acid value, preferably 1 to 100 mgKOH / g, and more preferably 1 to 60 mgKOH / g, from the viewpoint of particularly excellent balance between adhesion of the printed layer (W) to the plastic film and ink stability when a curing agent is added. When the aqueous acrylic urethane resin has an acid value, good water solubility is obtained. In addition, when a curing agent (E) described later is used in combination, a robust printed layer (W) can be obtained by crosslinking with the curing agent.

[0032] The aqueous acrylic urethane resin can be obtained by reacting a polyisocyanate compound, a polyol compound, and a hydroxyl group-containing (meth)acrylate, or a polyisocyanate compound and a hydroxyl group-containing (meth)acrylate, by a known method.

[0033] The aqueous acrylic urethane resin may be a commercially available product, such as those available from Taisei Fine Chemical Co., Ltd. under the trade names "WEM-200U," "WEM-505C," and "WEM-3000." The aqueous acrylic urethane resin may be used alone or in combination of two or more kinds.

[0034] (Water-based urethane resin) The aqueous urethane resin may be, for example, a reaction product of a polyisocyanate compound and a polyol compound. The polyisocyanate compound is an organic compound having at least two isocyanate groups in one molecule. The polyol compound is an organic compound having at least two hydroxyl groups in one molecule. Examples of the polyisocyanate compound include the polyisocyanate compounds exemplified above in the description of the aqueous acrylic urethane resin. Examples of the polyol compound include the polyol compounds exemplified above in the description of the aqueous acrylic urethane resin.

[0035] The weight average molecular weight of the aqueous urethane resin is preferably 3000 to 100000, more preferably 7000 to 90000, and from the viewpoint of achieving a particularly excellent balance between the blocking resistance of the printed layer (W) and its adhesion to the plastic film, further preferably 20000 to 80000. When the weight average molecular weight of the aqueous urethane resin is equal to or more than the above lower limit, the blocking resistance of the printed layer (W) is improved, and when it is equal to or less than the above upper limit, the adhesion of the printed layer (W) to the plastic film is improved.

[0036] The glass transition temperature of the aqueous urethane resin is preferably −10 to 130° C., more preferably 20 to 120° C., and from the viewpoint of achieving a particularly excellent balance between the blocking resistance of the printed layer (W) and its adhesion to the plastic film, further preferably 40 to 100° C. When the glass transition temperature of the aqueous urethane resin is equal to or higher than the above lower limit, the blocking resistance of the printed layer (W) is improved, and when it is equal to or lower than the above upper limit, the adhesion of the printed layer (W) to the plastic film is improved.

[0037] The aqueous urethane resin preferably has an acid value, preferably 1 to 60 mgKOH / g, and more preferably 1 to 50 mgKOH / g, from the viewpoint of particularly excellent balance of adhesion of the printed layer (W) to the plastic film, crosslinking density with the curing agent, and ink stability when the curing agent is added. When the aqueous urethane resin has an acid value, good water solubility is obtained. In addition, when the curing agent (E) described later is used in combination, a robust printed layer (W) can be obtained by crosslinking with the curing agent.

[0038] The aqueous urethane resin can be obtained, for example, by reacting a polyisocyanate compound with a polyol compound by a known method. Alternatively, a silanol group may be introduced into the reaction product of a polyisocyanate compound and a polyol compound by reacting the reaction product with a hydrolyzable silicon group-containing compound. In this specification, the aqueous urethane resin into which a silanol group has been introduced is also referred to as a "silanol group-containing aqueous urethane resin." The hydrolyzable silicon group-containing compound is a compound that contains a hydrolyzable silicon group, and preferably contains an active hydrogen group in addition to the hydrolyzable silicon group. The hydrolyzable silicon group includes a group in which a hydrolyzable group generated when hydrolyzed in the presence or absence of a silanol condensation catalyst is bonded to a silicon atom.The hydrolyzable group includes, for example, a hydrogen atom, a halogen atom, an alkoxy group, an acyloxy group, a ketoximate group, an amino group, an amide group, an aminooxy group, a mercapto group, an alkenyloxy group, etc.Usually, one to three hydrolyzable groups are bonded to one silicon atom. Examples of the active hydrogen group include an amino group, a hydroxyl group, and a mercapto group.

[0039] As the aqueous urethane resin, commercially available products may be used, such as "HYDRAN WLS-210" manufactured by DIC Corporation, "NEOSTICKER 400" and "NEOSTICKER 200" manufactured by NICCA Chemical Co., Ltd., "SUPERFLEX 500M" manufactured by Daiichi Kogyo Seiyaku Co., Ltd., and "TAKELACK WS-5000", "TAKELACK W-6010", "TAKELACK WS-5100", "TAKELACK WS-4000", and "TAKELACK W-635" manufactured by Mitsui Chemicals, Inc. The aqueous urethane resin may be used alone or in combination of two or more kinds.

[0040] <Water-repellent silicone (B)> The water-repellent silicone (B) is used to improve the resistance of the resulting printed layer (W) to lubricants for belt conveyors. The water-repellent silicone (B) is a compound having a siloxane bond.

[0041] Examples of the water-repellent silicone (B) include polyorganosiloxanes such as polydimethylsiloxane. The polyorganosiloxane may be partially modified with an organic group or may not be modified, but modification with an organic group is preferable because it increases the water repellency of the resulting printing layer (W). It is also preferable because it increases the solubility and dispersibility in the aqueous medium (D). The polyorganosiloxane may be reactive or non-reactive, but it is preferable that it is reactive when used in combination with the curing agent (E) described below. In this specification, polyorganosiloxanes partially modified with organic groups are also referred to as "modified polyorganosiloxanes".

[0042] The modified polyorganosiloxane may be, for example, a polyorganosiloxane in which at least one or more methyl groups in polydimethylsiloxane are substituted with a monovalent group other than an alkyl group (hereinafter also referred to as an "organic group"). In this embodiment, at least one or more terminal methyl groups and side chain methyl groups may be substituted with an organic group, at least one or more terminal methyl groups may be substituted with an organic group and the side chain methyl group may not be substituted with an organic group, or at least one or more side chain methyl groups may be substituted with an organic group and the terminal methyl group may not be substituted with an organic group. Among them, it is preferable that at least one or more side chain methyl groups are substituted with an organic group and the terminal methyl group is not substituted with an organic group.

[0043] Examples of the organic group include an organic group having an ether group, an organic group having an amino group, an organic group having an epoxy group (including a cyclic epoxy group), an organic group having an ester group, an organic group having an aryl group such as a phenyl group, an organic group having a hydroxyl group, an organic group having a mercapto group, an organic group having a carboxy group, an organic group having a (meth)acryloyloxy group, an organic group having an alkoxy group, and an organic group having an amide group. The organic group contained in the water-repellent silicone (B) may be of one type or of two or more types.

[0044] That is, examples of the modified polyorganosiloxane include polyether-modified polyorganosiloxane, amino-modified polyorganosiloxane, epoxy-modified polyorganosiloxane, polyester-modified polyorganosiloxane, polyetherester-modified polyorganosiloxane, aryl-modified polyorganosiloxane, hydroxyl-modified polyorganosiloxane, mercapto-modified polyorganosiloxane, carboxy-modified polyorganosiloxane, (meth)acryloyloxy-modified polyorganosiloxane, alkoxy-modified polyorganosiloxane, amide-modified polyorganosiloxane, etc. Among these, amino-modified polyorganosiloxane is preferred from the viewpoint of increasing the water repellency of the printing layer (W). These water-repellent silicones (B) may be used alone or in combination of two or more.

[0045] As the water-repellent silicone (B), commercially available products may be used. Examples of commercially available products include those manufactured by BYK under the trade names "BYK302", "BYK-307", "BYK313", "BYK322", "BYK323", "BYK325N", "BYK326", "BYK327", "BYK330", "BYK331", "BYK-333", "BYK342", "BYK-345", "BYK-346", "BYK347", "BYK-348", "BYK349", "BYK-375", "BYK377", "BYK378", "BYK3450", "BYK3451", "BYK3455", "BYK3456", "BYK3760", "BYK3550", "BYK SILCLEAN 3700", "BYK SILCLEAN 3701", and "BYK SILCLEAN 3720"; trade names of Shin-Etsu Chemical Co., Ltd.: "KF-351A", "KF-352A", "KF-353", "KF-354L", "KF-355A", "KF-615A", "KF-945", "KF-640", "KF-642", "KF-643", "KF-6020", "X-22-4515", "KF-868", "KF-865", "KF-864", "KF-859", "KF-393", "KF-860", "KF-880", "KF-8004", "KF-8002", "KF-8005", "KF-867", "KF-869", "KF-861", "X-22-343", "KF-101", "KF-1001", "X-22-2000", "X-22-38" 20W”, “X-22-3939A”, “KP-124”, “KP-109”, “KP-110”, “KP-121”, “KP-118”, “KP-341”, “KP-1” 12'', ``KP-125'', ``KP-101'', ``KP-106'', ``KP-126'', ``KP-360A'', ``KP-361'', ``KP-390'', ``KP-391'' , "KP-392", "PAM-E", "KF-8010", "X-22-161A", "X-22-161B", "KF-8012", "KF-8008", "POLO N-MF-14”, “POLON-MF-14E”, “POLON-MF-51”, “POLON-MF-14EC”, “POLON-MF-63”, “KM-9771”;Product names manufactured by Dow Toray Industries, Inc. "DOWSIL 501W Additive", "DOWSIL FZ-2104 Fluid", "DOWSIL FZ-2110", "DOWSIL FZ-2123", "DOWSIL FZ-2164", "DOWSIL FZ-2191", "DOWSIL FZ-5609 Fluid", "DOWSIL "DOWSIL L-7001", "DOWSIL L-7002", "DOWSIL L-7604", "DOWSIL OFX-0309 Fluid", "DOWSIL OFX-5221 Fluid", "DOWSIL SF-8410 Fluid", "DOWSIL OFX-0193 Fluid", "DOWSIL SH-3746 Fluid", "DOWSIL SH-3771 "DOWSIL SH-8400 Fluid", "DOWSIL SH-8700 Fluid", "DOWSIL Y-7006", "DOWSIL FZ-2203", "DOWSIL FZ-2215", "DOWSIL FZ-2222", "DOWSIL BY16-205", "DOWSIL BY16-213", "DOWSIL BY16-849 Fluid", "DOWSIL BY16-853U", "DOWSIL BY16-871", "DOWSIL BY16-872", "DOWSIL BY16-879B", "DOWSIL BY16-892", "DOWSIL FZ-3705", "DOWSIL FZ-3710 Fluid", "DOWSIL FZ-3785", "DOWSIL SF-8417 Fluid"; and the trade name "Tegoglide 482" manufactured by EVONIK.

[0046] The water-repellent silicone (B) may be in the form of a solid, an oil, an emulsion, or a dispersion. The water-repellent silicone (B) may be copolymerized with an acrylic resin skeleton, in which case compatibility with the aqueous binder resin (A) is enhanced when the aqueous binder resin (A) contains an aqueous acrylic resin.

[0047] <Titanium oxide (C)> Titanium oxide (C) is not particularly limited, but titanium oxide having a rutile crystal structure is preferred. Titanium oxide is preferably surface-treated with at least one of silica and alumina. That is, it is preferred that the surface has a treatment layer formed by surface treatment with at least one of silica and alumina. By having the treatment layer, printability is improved. Titanium oxide (C) may be treated with other metals or oxides. Examples of other metals include simple metals such as Si, Al, Zn, and Zr; and oxides of Al, Zn, and the like. The term "treated" for titanium oxide (C) refers to a state in which the surfaces of titanium oxide particles are coated.

[0048] The oil absorption of the titanium oxide (C) is preferably from 10 to 40 mL / 100 g, and more preferably from 15 to 30 mL / 100 g. The oil absorption of titanium oxide (C) is determined in accordance with JIS K 5101-13-1:2004.

[0049] The average particle size of the titanium oxide (C) is preferably from 0.15 to 0.35 μm, more preferably from 0.20 to 0.30 μm. The average particle size of titanium dioxide (C) is determined by directly measuring the size of primary particles from images observed under a transmission electron microscope (TEM). Specifically, the particle size of each of 100 randomly selected primary particles is measured, and the average particle size of titanium dioxide (C) is calculated.

[0050] Titanium oxide (C) may be a commercially available product. Examples of commercially available products include those manufactured by Ishihara Sangyo Kaisha Ltd. under the trade names "CR-50", "CR-50-2", "CR-57", "CR-Super70", "CR-80", "CR-90", "CR-90-2", "CR-93", "CR-95", "CR-953", "CR-97", "UT771", "CR-60", "CR-60-2", "CR-63", "CR-67", "CR-58", "CR-58-2", "CR-85", "R-820", "R-830", "R-930", "R-980", "R-550", "R-630", "R-680", "R-780", "R-780-2", and "R-850". Examples of such products include "A-100", "A-220", and "W-10"; product names manufactured by Teika Corporation: "JR-301", "JR-403", "JR-405", "JR-600A", "JR-605", "JR-600E", "JR-603", "JR-805", "JR-806", "JR-701", "JRNC", "JR-800", "JA-1", "JA-C", "JA-3", "JA-4", and "JA-5"; and product names manufactured by Sakai Chemical Industry Co., Ltd.: "A-190", "R-25", "R-21", "R-32", "R-33", "R-7E", "R-62N", "R-78", "R-42", and "R-45M". These titanium oxides (C) may be used alone or in combination of two or more.

[0051] <Optional ingredients> Examples of the optional components include an aqueous medium (D) and additives.

[0052] (Aqueous medium (D)) Examples of the aqueous medium (D) include water and a mixed solvent of water and an organic solvent. The organic solvent in the mixed solvent is not particularly limited as long as it is soluble in water, and examples thereof include alcohol-based solvents such as methanol, ethanol, propanol, n-butanol, i-butanol, etc.; ketone-based solvents such as acetone, etc.; glycol ether-based solvents such as propylene glycol monomethyl ether, etc. These organic solvents may be used alone or in combination of two or more.

[0053] The content of water relative to the total mass of the aqueous medium (D) is preferably from 60 to 100 mass %, more preferably from 70 to 100 mass %, and even more preferably from 80 to 100 mass %.

[0054] (Additives) Examples of the additives include waxes, thickeners, anti-settling agents, UV absorbers, antioxidants, leveling agents, viscoelasticity modifiers, antifoaming agents, lubricants, dispersants, stabilizers, and pH adjusters. These additives may be used alone or in combination of two or more. It is preferable that the water-based white ink composition does not substantially contain any colorant such as a pigment other than titanium oxide (B). Here, the term "substantially free" means that, except for colorants that are unintentionally contained, no colorants are intentionally blended.

[0055] Examples of waxes include polyolefin waxes (polyethylene wax, polypropylene wax, etc.), polytetrafluoroethylene wax, Fischer-Tropsch wax, amide wax, microcrystalline wax, montan wax, carnauba wax, paraffin wax, beeswax, etc. Among these, polyolefin waxes are preferred, and polyethylene wax is more preferred.

[0056] Commercially available polyethylene waxes include those manufactured by Mitsui Chemicals under the trade names "CHEMIPERL W100", "CHEMIPERL W200", "CHEMIPERL W300", "CHEMIPERL W308", "CHEMIPERL W400", "CHEMIPERL W401", "CHEMIPERL W500", "CHEMIPERL W640", "CHEMIPERL W700", and "CHEMIPERL W800"; and those manufactured by BYK under the trade names "CERAFLOUR925", "CERAFLOUR925N", "CERAFLOUR927N", and "CERAFLOUR929". "CERAFLOUR929N", "CERAFLOUR950", "CERAFLOUR960", "CERAFLOUR961", "CERAFLOUR988", "CERAFLOUR991", "CERAFLOUR1000", "AQUACER531", "AQUACER537", "AQUACER552", "AQUACER840", "AQUACER1547", "AQUAMAT208"; and "John Kryllwax 4", a product name manufactured by BASF Japan. These waxes may be used alone or in combination of two or more kinds.

[0057] The thickener is used to adjust the viscosity of the water-based white ink composition. Examples of the thickener include urethane-based thickeners, polyacrylic-based thickeners, polyamide-based thickeners, cellulose-based thickeners, clay minerals such as bentonite, etc. Among these, urethane-based thickeners are more preferred. The urethane-based thickener is a so-called association type thickener, and effectively exhibits a thickening effect by association of urethane bonds with each other in the aqueous medium (D). Examples of the urethane-based thickener (urethane association type thickener) include compounds having urethane bonds and polyether chains in the molecule and having hydrophobic groups at the ends. Examples of commercially available urethane thickeners include those manufactured by San Nopco Ltd. under the trade names "SN Thickener 612," "SN Thickener 621N," "SN Thickener 625N," "SN Thickener 627N," and "SN Thickener 660T." These thickeners may be used alone or in combination of two or more kinds.

[0058] The defoaming agent is used to defoam the water-based white ink composition. The antifoaming agent includes a mixture of silicone and hydrophobic particulates. Commercially available mixtures of silicone and hydrophobic microparticles include those manufactured by BYK under the trade names "BYK-011", "BYK-012", "BYK-014", "BYK-015", "BYK-017", "BYK-018", "BYK-019", "BYK-021", "BYK-022", "BYK-023", "BYK-024", "BYK-025", "BYK-028", "BYK-038", "BYK-039", "BYK-044", "BYK-093", "BYK-095", "BYK-096", "BYK-097", "BYK-098", "BYK-099", "BYK-1000", "BYK-1010", "BYK-1020", "BYK-1030", "BYK-1040", "BYK-1050", "BYK-1060", "BYK-1070", "BYK-1080", "BYK-1090", "BYK-1100", "BYK-111", "BYK-112", "BYK-114", "BYK-115", "BYK-117", "BYK-118", "BYK-119", "BYK-121", "BYK-122", "BYK-123", "BYK-124", "BYK-125", "BYK-128", "BYK-123", "BYK-125", "BYK-126", "BYK-127", "BYK-128", "BYK-129", "BYK-130", "BYK-131", "BYK-132", "BYK-133", "BYK-134", "BYK-135", "BYK-136", BYK-094", "BYK-1610", "BYK-1611", "BYK-1615", "BYK-1617", "BYK-1640", "BYK-1650", "BYK-1710", "BYK-1711", "BYK-1 719'', ``BYK-1723'', ``BYK-1724'', ``BYK-1730'', ``BYK-1740'', ``BYK-1770'', ``BYK-1780'', ``BYK-1781'', ``BYK-1785'', ``BYK-1786'' , "BYK-1798"; San Nopco product names: "SN Deformer 121N", "SN Deformer 1311", "SN Deformer 1312", "SN Deformer 1313", "SN Deformer 1314", "SN Deformer 1315", "SN Deformer 1316", "SN Deformer 154", "SN Deformer 154S", "SN Deformer 180", "SN Deformer 265", "SN Deformer 317", "SN Deformer Examples of these include "SN Deformer 380", "SN Deformer 381", "SN Deformer 391", "SN Deformer 393", "SN Deformer 395", "SN Deformer 399", "SN Deformer 5016", "SN Deformer 5016", "Nopco DF-122-NS", "Noptum 3590", "Noptum 6030PC", "Noptum 777-F", "Noptum 8000PC", "Noptum 8034-F", and "Noptum 8034-LF". These antifoaming agents may be used alone or in combination of two or more.

[0059] The dispersant is used to enhance the dispersibility of the titanium oxide (C) in the water-based white ink composition. The dispersant may be a copolymer having an affinity for the pigment. Commercially available dispersants include those manufactured by BYK under the trade names "ANTI-TERRA-250", "DISPERBYK-102", "DISPERBYK-180", "DISPERBYK-184", "DISPERBYK-185", "DISPERBYK-187", "DISPERBYK-190", "DISPERBYK-191", "DISPERBYK-192", "DISPERBYK-193", "DISPERBYK-194N", "DISPERBYK-199", "DISPERBYK-2010", "DISPERBYK-2012", "DISPERBYK-2013", "DISPERBYK-2015", "DISPERBYK-2019", "DISPERBYK-2055", "DISPERBYK-2060", and "DISPERBYK-2070". 061", "DISPERBYK-2081", "DISPERBYK-2096", "BYK-154"; and trade names manufactured by Lubrizol include "Solsperse 20000", "Solsperse 40000", "Solsperse 43000", "Solsperse 27000", "Solsperse 40000", "Solsperse 41000", "Solsperse 43000", "Solsperse 44000", "Solsperse 45000", "Solsperse 46000", "Solsperse 47000", "Solsperse 53095", "Solsperse 64000", "Solsperse 65000", "Solsperse 66000", "Solsperse W100", "Solsperse W200", "Solsperse W320", "Solsperse WV400", and "Solsperse J400". These dispersants may be used alone or in combination of two or more kinds.

[0060] Examples of the pH adjuster include aqueous ammonia, sodium hydroxide, potassium hydroxide, and various amines. These pH adjusters may be used alone or in combination of two or more.

[0061] <Content of each ingredient> The content of the aqueous binder resin (A) is preferably 5 to 40% by mass, more preferably 7 to 35% by mass, based on the total mass of the aqueous white ink composition, and from the viewpoint of particularly excellent balance of adhesion of the printed layer (W) to the plastic film, pigment dispersibility, ink fluidity, ink storage stability, printability, scratch resistance, abrasion resistance, water abrasion resistance, and hiding power (transmission density), it is further preferably 9 to 30% by mass. When the content of the aqueous binder resin (A) is equal to or greater than the above lower limit, the adhesion of the printed layer (W) to the plastic film, pigment dispersibility, ink fluidity, ink storage stability, printability, scratch resistance, abrasion resistance, and water abrasion resistance of the printed layer (W) are improved. When the content of the aqueous binder resin (A) is equal to or less than the above upper limit, the transmission density of the printed layer (W) is high, and hiding power is improved. The content of the aqueous binder resin (A) is preferably 7 to 80% by mass, more preferably 10 to 70% by mass, and even more preferably 12 to 60% by mass, based on the total mass of the non-volatile content of the aqueous white ink composition. From the viewpoint of particularly excellent balance of adhesion of the printed layer (W) to the plastic film, pigment dispersibility, ink storage stability, printability, scratch resistance, abrasion resistance, water abrasion resistance, and hiding power (transmission density), 15 to 50% by mass is particularly preferred. When the content of the aqueous binder resin (A) is equal to or greater than the above lower limit, the adhesion of the printed layer (W) to the plastic film, pigment dispersibility, ink fluidity, ink storage stability, printability, scratch resistance, abrasion resistance, and water abrasion resistance of the printed layer (W) are improved. When the content of the aqueous binder resin (A) is equal to or less than the above upper limit, the transmission density of the printed layer (W) is high, and hiding power is improved.

[0062] When the aqueous binder resin (A) contains an acrylic resin emulsion and a water-soluble acrylic resin, the blending ratio thereof, by mass ratio, is preferably acrylic resin emulsion:water-soluble acrylic resin=75:25 to 99:1, more preferably 80:20 to 99:1, even more preferably 80:20 to 98:2, particularly preferably 80:20 to 97:3, and is most preferably 85:15 to 95:5 from the viewpoint of achieving a particularly excellent balance of pigment dispersibility, ink fluidity, ink storage stability, resolubility, printability, water resistance, abrasion resistance, water-abrasion resistance of the printing layer (W), and adhesion to plastic films. When the blending ratio of the acrylic resin emulsion and the water-soluble acrylic resin is within the above range, the printed layer (W) has an excellent balance of adhesion to the plastic film, dispersibility of the titanium oxide (C) in the water-based white ink composition, ink fluidity, storage stability, resolubility, printability of the ink, and water resistance, abrasion resistance, and water-abrasion resistance of the printed layer (W).

[0063] The content of the water-repellent silicone (B) is preferably 0.04% by mass or more, more preferably 0.08% by mass or more, and even more preferably 0.15% by mass or more, based on the total mass of the water-based white ink composition. In order to improve the resistance of the printed layer (W) to belt conveyor lubricants, and the blocking resistance, abrasion resistance, water resistance, and heat resistance of the printed layer (W), it is particularly preferable that it is 0.2% by mass or more. The content of the water-repellent silicone (B) is preferably 2% by mass or less, more preferably 1% by mass or less, and even more preferably 0.8% by mass or less, based on the total mass of the water-based white ink composition. In order to improve the lamination property when further printing is performed on the printed layer (W) and to prevent craters when printing on a plastic film, it is particularly preferable that it is 0.5% by mass or less. The above upper limit value and the above lower limit value of the content of the water-repellent silicone (B) can be arbitrarily combined. The content of the water-repellent silicone (B) is preferably 0.05% by mass or more, more preferably 0.1% by mass or more, and even more preferably 0.2% by mass or more, based on the total mass of the non-volatile content of the water-based white ink composition. In order to improve the resistance of the printed layer (W) to belt conveyor lubricants, and the blocking resistance, abrasion resistance, water resistance, and heat resistance of the printed layer (W), it is particularly preferable that it is 0.3% by mass or more. The content of the water-repellent silicone (B) is preferably 5% by mass or less, more preferably 3% by mass or less, even more preferably 2% by mass or less, even more preferably 1.8% by mass or less, and especially preferably 1% by mass or less, based on the total mass of the non-volatile content of the water-based white ink composition. In order to improve the lamination property when further printing is performed on the printed layer (W) and to prevent craters when printing on a plastic film, it is most preferable that it is 0.5% by mass or less. The above upper limit value and the above lower limit value of the content of the water-repellent silicone (B) can be arbitrarily combined. When the content of the water-repellent silicone (B) is equal to or greater than the lower limit, the resistance of the printed layer (W) to belt conveyor lubricants, and the blocking resistance, abrasion resistance, water resistance, and heat resistance of the printed layer (W) are improved. When the content of the water-repellent silicone (B) is equal to or less than the upper limit, lamination properties are improved when further printing is performed on the printed layer (W), and craters are less likely to be formed when printing on a plastic film.

[0064] The mass ratio of the aqueous binder (A) to the mass of the water-repellent silicone (B) (hereinafter also referred to as the "(A) / (B) ratio") is preferably 5 to 300, more preferably 10 to 200, and even more preferably 20 to 150, and is particularly preferably 50 to 100 from the viewpoints of improving the resistance of the printed layer (W) to belt conveyor lubricants, the blocking resistance, abrasion resistance, water resistance, heat resistance, and adhesion to plastic films of the printed layer (W), and lamination properties when further printing is performed on the printed layer (W), and preventing craters when printing on a plastic film. When the (A) / (B) ratio is equal to or greater than the lower limit, lamination is improved when further printing is performed on the printed layer (W), and craters are less likely to form when printed on a plastic film.When the (A) / (B) ratio is equal to or less than the upper limit, the resistance of the printed layer (W) to belt conveyor lubricants, and the blocking resistance, abrasion resistance, water resistance, and heat resistance of the printed layer (W) are improved.

[0065] The content of titanium oxide (C) is preferably 20% by mass or more, more preferably 25% by mass or more, and even more preferably 30% by mass or more, based on the total mass of the aqueous white ink composition, and is particularly preferably 35% by mass or more in terms of high transmission density and improved hiding power of the printed layer (W). The content of titanium oxide (C) is preferably 60% by mass or less, more preferably 55% by mass or less, and even more preferably 50% by mass or less, based on the total mass of the aqueous white ink composition, and is particularly preferably 45% by mass or less in terms of improved ink fluidity, ink stability, printability, scratch resistance, and abrasion resistance of the printed layer (W). The upper limit value and the lower limit value of the content of titanium oxide (C) can be arbitrarily combined. The content of titanium oxide (C) is preferably 30% by mass or more, more preferably 35% by mass or more, and even more preferably 40% by mass or more, and particularly preferably 50% by mass or more, from the viewpoint of high transmission density and improved hiding power of the printed layer (W). The content of titanium oxide (C) is preferably 90% by mass or less, more preferably 85% by mass or less, even more preferably 80% by mass or less, and particularly preferably 75% by mass or less, and most preferably 70% by mass or less, from the viewpoint of improved ink fluidity, ink stability, printability, scratch resistance, and abrasion resistance of the printed layer (W). The above upper limit value and the above lower limit value of the content of titanium oxide (C) can be arbitrarily combined. When the content of titanium oxide (C) is equal to or greater than the lower limit, a printed matter having a high transmission density and good hiding power can be obtained in the printed layer (W).When the content of titanium oxide (C) is equal to or less than the upper limit, a water-based white ink composition having good ink fluidity, ink stability, printability, scratch resistance, and abrasion resistance of the printed layer (W) can be obtained.

[0066] The content of the aqueous medium (D) is preferably 20 to 60 mass %, more preferably 25 to 55 mass %, and even more preferably 30 to 50 mass %, based on the total mass of the aqueous white ink composition. When the content of the aqueous medium (D) is equal to or more than the lower limit, the fluidity of the aqueous white ink composition is good, and when it is equal to or less than the upper limit, the drying property of the coating film of the aqueous white ink composition, i.e., the printed layer (W), is good. The content of the organic solvent is preferably 0 to 5% by mass, more preferably 0 to 4% by mass, and even more preferably 0 to 3% by mass, based on the total mass of the aqueous white ink composition. If the content of the organic solvent exceeds 5% by mass, the ink tends to dry too quickly during flexographic printing, resulting in printing defects such as plate tangles.

[0067] The content of optional components other than the aqueous medium (D) is not particularly limited as long as it is within a range that does not impair the effects of the present invention. For example, the content is preferably 0 to 10 mass %, and more preferably 0 to 5 mass %, relative to the total mass of the aqueous white ink composition. The content of optional components other than the aqueous medium (D) is preferably from 0 to 15 mass %, more preferably from 0 to 10 mass %, based on the total mass of the non-volatile components of the aqueous white ink composition.

[0068] When the water-based white ink composition contains a wax as an optional component, the content of the wax is preferably 0.1 to 10 mass %, more preferably 0.2 to 5 mass %, and even more preferably 0.3 to 3 mass %, relative to the total mass of the water-based white ink composition. When the water-based white ink composition contains a wax as an optional component, the content of the wax is preferably 0.2 to 20 mass%, more preferably 0.4 to 10 mass%, and even more preferably 0.6 to 6 mass%, relative to the total mass of the non-volatile matters in the water-based white ink composition.

[0069] When the water-based white ink composition contains a thickener as an optional component, the content of the thickener is preferably 0.01 to 4 mass%, more preferably 0.03 to 2 mass%, and even more preferably 0.08 to 1 mass%, relative to the total mass of the water-based white ink composition. When the water-based white ink composition contains a thickener as an optional component, the content of the thickener is preferably 0.02 to 7 mass%, more preferably 0.05 to 4 mass%, and even more preferably 0.1 to 2 mass%, relative to the total mass of the non-volatile matters in the water-based white ink composition. When the content of the thickener is equal to or more than the above lower limit, the effect of the thickener is fully exerted and the viscosity of the water-based white ink composition can be easily adjusted to a desired value, whereas when the content is equal to or less than the above upper limit, the physical properties of the water-based white ink composition can be well maintained.

[0070] When the water-based white ink composition contains an antifoaming agent as an optional component, the content of the antifoaming agent is preferably 0.01 to 2 mass %, more preferably 0.05 to 1 mass %, and even more preferably 0.1 to 0.8 mass %, relative to the total mass of the water-based white ink composition. When the water-based white ink composition contains an antifoaming agent as an optional component, the content of the antifoaming agent is preferably 0.02 to 4 mass%, more preferably 0.05 to 2 mass%, and even more preferably 0.1 to 1 mass%, relative to the total mass of the non-volatile matters in the water-based white ink composition.

[0071] When the water-based white ink composition contains a dispersant as an optional component, the content of the dispersant is preferably 0.1 to 10 mass% relative to the total mass of the water-based white ink composition, more preferably 0.2 to 5 mass%, and from the viewpoint of improving pigment dispersibility, ink storage stability, ink fluidity, and water resistance of the printing layer (W), still more preferably 0.5 to 3 mass%. When the water-based white ink composition contains a dispersant as an optional component, the content of the dispersant is preferably 0.2 to 15 mass% relative to the total mass of the non-volatile components of the water-based white ink composition, more preferably 0.3 to 7 mass%, and from the viewpoint of improving pigment dispersibility, ink storage stability, ink fluidity, and water resistance of the printing layer (W), still more preferably 0.7 to 5 mass%.

[0072] When the water-based white ink composition contains a pH adjuster as an optional component, the content of the pH adjuster is preferably 0.01 to 5 mass %, more preferably 0.02 to 3 mass %, and even more preferably 0.05 to 2 mass %, relative to the total mass of the water-based white ink composition.

[0073] <Method for producing water-based white ink composition> The water-based white ink composition of this embodiment can be obtained, for example, by mixing a water-based binder resin (A), a water-repellent silicone (B), titanium oxide (C), and, as necessary, one or more optional components, so that each component has a desired content. The method for mixing the components is not particularly limited, and the components can be mixed by various methods.

[0074] <Applications of water-based white ink composition> The aqueous white ink composition of the present embodiment is suitable as a white ink for printing on the surface of a substrate such as a plastic film, or on the surface of a color ink layer formed on the surface of a substrate, by gravure printing or flexographic printing. In particular, it is suitable as a white ink for printing on the surface of a substrate, or on the surface of a color ink layer formed on the surface of a substrate, by flexographic printing. That is, the aqueous white ink composition of the present embodiment is suitable for flexographic printing. The water-based white ink composition of the present embodiment is also suitable as a white ink for use on labels, particularly labels for food and beverage products that require a lubricant for belt conveyors. The water-based white ink composition of this embodiment is preferably used together with a curing agent (E) described below.

[0075] <Action and effect> As described above, the water-based white ink composition of the present embodiment has a coating weight of 2 g / m after drying by flexographic printing. 2 The water contact angle of the dry coating film formed by printing so as to be as above is 90° or more. A water contact angle of 90° or more means that the dry coating film has excellent water repellency. It is considered that the excellent water repellency of the dry coating film (printed layer (W)) improves the resistance to an aqueous solution containing a surfactant, specifically, a lubricant for a belt conveyor.

[0076] In addition, when blending a pigment into a varnish composition that does not substantially contain a colorant such as a pigment, it is necessary to take into consideration the dispersibility of the pigment. Therefore, the water-based white ink composition of the present embodiment is completely different from a varnish composition.

[0077] <Hardening agent (E)> The hardener (E) is used to further improve the resistance of the printed layer (W) to belt conveyor lubricants and adhesion to plastic films. In addition, the use of the hardener (E) improves the water resistance of the printed layer (W).

[0078] As the curing agent (E), known ones can be used, such as isocyanate-based curing agents, blocked isocyanate-based curing agents, carbodiimide-based curing agents, oxazoline-based curing agents, epoxy-based curing agents, aziridine-based curing agents, etc. Among these, from the viewpoint of further improving the scratch resistance of the printing layer (W), isocyanate-based curing agents, epoxy-based curing agents, and aziridine-based curing agents are preferred. These curing agents (E) may be used alone or in combination of two or more.

[0079] Specific examples of the isocyanate-based curing agent include the polyisocyanate compounds exemplified above in the explanation of the aqueous acrylic urethane resin. Commercially available isocyanate-based curing agents include those manufactured by Mitsui Chemicals, Inc. under the product names "Takenate WD-720," "Takenate WD-725," "Takenate WD-726," "Takenate WD-730," "Takenate WD-220," "Takenate XWD-HS7," and "Takenate XWD-HS30"; those manufactured by Nippon Polyurethane Industry Co., Ltd. under the product names "Aquanate 100," "Aquanate 110," "Aquanate 200," and "Aquanate 210"; those manufactured by Asahi Kasei Corporation under the product names "Duranate WB40-100," "Duranate WB40-80D," "Duranate WT20-100," "Duranate WT30-100," "Duranate WL70-100," "Duranate WR80-70P," and "Duranate WE50-100"; and those manufactured by Bayer MaterialScience under the product names "Bayhydur 3100", "Bayhydur 302", "Bayhydur 304", "Bayhydur 305", "Bayhydur XP2451 / 1", "Bayhydur XP2487 / 1", "Bayhydur XP2547", "Bayhydur XP2655", "Bayhydur XP2700"; and BASF products under the names "Basonat HW100", "Basonat HA100", and "Basonat HW1180PC". The isocyanate-based curing agent may be used alone or in combination of two or more kinds.

[0080] Specific examples of blocked isocyanate curing agents include those blocked with a blocking agent of an isocyanate curing agent (e.g., an alcohol-based compound, a phenol-based compound, an oxime-based compound, a lactam-based compound, a pyrazole-based compound, an active methylene compound, etc.). These blocked isocyanate curing agents may be used alone or in combination of two or more.

[0081] A carbodiimide-based curing agent is a compound containing two or more carbodiimide groups in one molecule. Specific examples of carbodiimide-based curing agents include poly(4,4'-diphenylmethanecarbodiimide), poly(dicyclohexylmethanecarbodiimide), and poly(diisopropylcarbodiimide). Commercially available carbodiimide-based curing agents include the "Carbodilite" series manufactured by Nisshinbo Chemical Inc. These carbodiimide-based curing agents may be used alone or in combination of two or more kinds.

[0082] An oxazoline-based curing agent is a compound containing two or more oxazoline groups in one molecule. Specific examples of oxazoline-based curing agents include polyvalent oxazolines such as 2,2'-bis-(2-oxazoline), 2,2'-methylene-bis-(2-oxazoline), and 2,2'-(1,4-phenylene)-bis(2-oxazoline), and polymers or copolymers having oxazoline-group-containing monomer units such as 2-vinyl-2-oxazoline, 2-vinyl-5-methyl-2-oxazoline, and 2-isopropenyl-5-ethyl-2-oxazoline. The oxazoline-group-containing monomers may be used alone or in combination of two or more kinds. In addition, the oxazoline-group-containing monomer may be a copolymer of another monomer copolymerizable with the monomer. Commercially available oxazoline-based curing agents include the "Epocross" series manufactured by Nippon Shokubai Co., Ltd. These oxazoline-based curing agents may be used alone or in combination of two or more kinds.

[0083] An epoxy-based curing agent is a compound containing two or more epoxy groups in one molecule. Specific examples of epoxy-based curing agents include bisphenol A type epoxy compounds, bisphenol F type epoxy compounds, triglycidyl aminophenol, biphenyl diglycidyl ether, triglycidyl isocyanurate, polyglycidyl (meth)acrylate, and copolymers of glycidyl (meth)acrylate and vinyl monomers copolymerizable therewith. Commercially available epoxy-based curing agents include the "jER" series manufactured by Mitsubishi Chemical Corporation and the "Denacol EX" series manufactured by Nagase ChemteX Corporation. These epoxy-based curing agents may be used alone or in combination of two or more.

[0084] Aziridine-based curing agents are compounds that contain two or more aziridine groups in one molecule. Specific examples of aziridine-based curing agents include 2,2-bishydroxymethylbutanol-tris[3-(1-aziridinyl)propionate] and 4,4'-bis(ethyleneiminocarbonylamino)diphenylmethane. Commercially available aziridine-based curing agents include the "ChemiTite" series manufactured by Nippon Shokubai Co., Ltd. These aziridine-based curing agents may be used alone or in combination of two or more kinds.

[0085] When the water-based white ink composition and the curing agent (E) are used in combination, it is preferable to mix them so that the non-volatile content of the curing agent (E) is 0.1 to 10 parts by mass, more preferably 0.3 to 7 parts by mass, and even more preferably 0.5 to 5 parts by mass, per 100 parts by mass of the non-volatile content of the water-based white ink composition. When the ratio of the curing agent (E) is equal to or higher than the lower limit, the curing reaction proceeds sufficiently, and when the ratio is equal to or lower than the upper limit, the water resistance of the printing layer (W) is further improved.

[0086] [kit] A kit according to one embodiment of the present invention independently contains the water-based white ink composition of the present invention and the curing agent (E) described above. Here, "independently" means that the water-based white ink composition and the curing agent (E) are present in a state where they are not in contact with each other. For example, the kit includes a first container containing the water-based white ink composition and a second container containing the curing agent (E).

[0087] The second container may contain components other than the curing agent (E) (other components). Examples of other components include solvents and stabilizers. The solvent may be the aqueous medium (D) exemplified above in the description of the aqueous white ink composition.

[0088] When the kit is used, the water-based white ink composition and the curing agent (E) are mixed together. The mixing ratio when mixing the water-based white ink composition and the curing agent (E) is as described above.

[0089] [Laminate] An example of a laminate according to an embodiment of the present invention is shown in Figures 1 and 2. Note that the dimensional ratios in Figures 1 and 2 are different from the actual ones 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 printed layer 12 provided on one surface of the plastic film 11. The laminate 20 in Figure 2 is a printed matter comprising a base material, a plastic film 21, a first printed layer 22 provided on one side of the plastic film 21, and a second printed layer 23 provided on the side of the first printed layer opposite the plastic film. When the laminate is attached to a packaging container as a plastic label, it is preferable that the plastic films 11 and 21 are attached on the outer side of the printed layer 12 and the second printed layer 23, that is, the printed layer 12 and the second printed layer 23 are attached on the inner side (the side in contact with the packaging container). In addition, another printed layer may be provided on the surfaces of the plastic films 11 and 21 by printing a composition containing a matting agent such as a varnish composition or an extender pigment. Here, the surface of the plastic film 11 means the surface opposite to the surface of the plastic film 11 on which the printed layer 12 is provided. The surface of the plastic film 21 means the surface opposite to the surface of the plastic film 21 on which the first printed layer 22 is provided. In addition, the surface of the plastic film 11 on which the printed layer 12 is provided is referred to as the back surface of the plastic film 11, and the surface of the plastic film 21 on which the first printed layer 22 is provided is referred to as the back surface of the plastic film 21.

[0090] <Plastic film> The type of the plastic film 11, 21 can be appropriately selected according to the type of the laminate 10, 20, etc., and is not particularly limited. For example, when the laminate 10, 20 is used as a heat-shrinkable label (shrink label), the plastic film 11, 21 is preferably a heat-shrinkable film (shrink film). When the laminate 10, 20 is used as a roll label, the plastic film 11, 21 is preferably a polyethylene terephthalate (PET) film or a biaxially stretched PP film (OPP film). When the laminate 10, 20 is used as a stretch label, the plastic film 11, 21 is preferably a stretch film. Among these, the plastic film 11, 21 is preferably a heat-shrinkable film, a polyethylene terephthalate (PET) film, or a biaxially stretched PP film.

[0091] Examples of the plastic films 11 and 21 include polyester films such as polyethylene terephthalate (PET), amorphous polyethylene terephthalate (A-PET), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), and polylactic acid; polyolefin films such as low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), high-density polyethylene (HDPE), and polypropylene (PP); cellulose films such as cellophane; polystyrene (PS) films; ethylene-vinyl acetate copolymer resin films; ethylene-vinyl alcohol copolymer resin films; polyamide (Ny) films; polycarbonate films; polyimide films; and polyvinyl chloride films. These films can be appropriately selected depending on the application. For example, when the laminates 10 and 20 are used as heat-shrinkable labels (shrink labels), the plastic films 11 and 21 are preferably uniaxially shrinkable polystyrene films, uniaxially shrinkable PET films, uniaxially shrinkable polyolefin films, and uniaxially shrinkable polyvinyl chloride films. Both stretched and unstretched plastic films, such as biaxially stretched PP film and unstretched PP film, can be used as the plastic films 11 and 21. The surfaces of the plastic films 11 and 21 may be subjected to surface treatment such as corona discharge treatment, plasma treatment, flame treatment, and solvent treatment.

[0092] The plastic films 11 and 21 may have a single layer structure or a laminate structure. That is, the plastic films 11 and 21 may be single layer films or laminate films. When the plastic films 11 and 21 are laminate films, they may be configured by laminating two or more films of the same type, or may be configured by laminating two or more films of different types. Examples of preferred film combinations include a combination in which a polyester film is on the front side of the plastic films 11 and 21 and a polystyrene film or a polyolefin film is on the back side of the plastic films 11 and 21, a cyclic polyolefin film is on the front side of the plastic films 11 and 21, and a polyethylene film or a polypropylene film is on the back side of the plastic films 11 and 21, and the like.

[0093] The thickness of the plastic films 11, 21 is preferably from 5 to 100 μm, more preferably from 12 to 60 μm, and even more preferably from 12 to 50 μm.

[0094] <Printed layer, second printed layer> In the laminate 10, the printed layer 12 is provided on one surface of the plastic film 11. In the laminate 20, the second printed layer 23 is provided on the opposite surface of the plastic film 21 to the first printed layer 22 provided on one surface of the plastic film 21. The printed layer 12 and the second printed layer 23 are printed layers (W) formed using the water-based white ink composition or kit of the present embodiment described above. In the present invention, the printed layer 12, which is the printed layer (W) formed using the water-based white ink composition or kit, is also referred to as the "printed coating (W)" and the second printed layer 23 is also referred to as the "second printed coating (W)". The thickness of the printed layer 12 and the second printed layer 23 is preferably 0.2 to 3.0 μm, more preferably 0.3 to 2.0 μm, and further preferably 0.3 to 1.5 μm.

[0095] <First printing layer> In the laminate 20 , a first printed layer 22 is provided on one surface of a plastic film 21 . The first printed layer 22 is a printed layer (C) (hereinafter also referred to as "color printed layer (C)" or "printed coating film (C)") formed using an ink composition for the purpose of imparting design, functionality, etc. to the laminate 20. The first printed layer 22 may have a single-layer structure or a laminated structure. The total thickness of the first printed layer 22 is preferably from 0.2 to 15 μm, more preferably from 0.3 to 10 μm, and even more preferably from 0.3 to 8 μm.

[0096] The ink composition used to form the first printed layer 22 contains a color pigment. The ink composition is preferably an aqueous ink composition. The aqueous ink composition is not particularly limited, and any known composition can be used. For example, the aqueous ink composition may include a composition containing an aqueous binder resin, an aqueous medium, a color pigment, and other components as necessary. Examples of the aqueous binder resin include the aqueous binder resin (A) exemplified above in the description of the aqueous white ink composition of the present invention. Examples of the aqueous medium include the aqueous medium (D) exemplified above in the description of the aqueous white ink composition of the present invention. Examples of color pigments include organic pigments such as azo pigments (monoazo, condensed azo, etc.), threne pigments (anthraquinone, perinone, perylene, thioindigo, etc.), phthalocyanine pigments (phthalocyanine blue, phthalocyanine green, etc.), quinacridone pigments, dioxazine pigments, isoindolinone pigments, pyrrolopyrrole pigments, aniline black, and organic fluorescent pigments; and inorganic pigments such as natural products (clay, etc.), ferrocyanides (princess blue, etc.), sulfides (zinc sulfide, etc.), sulfates, oxides (chromium oxide, zinc oxide, iron oxide, etc.), hydroxides (aluminum hydroxide, etc.), silicates (ultramarine, etc.), carbonates, carbon (carbon black, graphite, etc.), metal powders (aluminum powder, bronze powder, zinc powder, etc.), and calcined pigments. Examples of color pigments include the above-mentioned titanium oxide (C). Examples of other components include waxes, dispersants, antifoaming agents, lubricants, pH adjusters, and thickeners.

[0097] <Method of manufacturing laminate> The method for producing the laminate 10 in FIG. 1 includes a step of forming a printed layer 12 on one surface of a plastic film 11 using the water-based white ink composition or kit of this embodiment. The manufacturing method of the laminate 20 in Figure 2 includes a step (1) of forming a first printed layer 22 on one side of a plastic film 21 using an ink composition, and a step (2) of forming a second printed layer 23 on the side of the first printed layer 22 opposite the plastic film 21 using the water-based white ink composition or kit of this embodiment.

[0098] In the method for producing the laminate 10 in FIG. 1, for example, the water-based white ink composition of the present embodiment is applied onto one surface of a plastic film 11 and dried to form a printed layer 12. When forming the printed layer 12 using the kit of this embodiment, the aqueous white ink composition and the curing agent (E) included in the kit are mixed to prepare a mixture (M), and the resulting mixture (M) is applied onto one surface of the plastic film 11 and dried to form the printed layer 12. The mixing ratio of the aqueous white ink composition and the curing agent (E) when mixing them is as described above. In addition, the water-based white ink composition or mixture (M) may be applied to one side of the plastic film 11, dried to form the printed layer 12, and then further water-based white ink composition or mixture (M) may be applied (recoated).

[0099] The method for applying the aqueous white ink composition or mixture is not particularly limited, and any known application method can be used, 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, curtain coating method, etc. Among these, flexographic printing is preferred because of its high quality and productivity.

[0100] The drying method is not particularly limited as long as it can remove the aqueous medium (D) contained in the aqueous white ink composition or mixture coated on one side of the plastic film 11, and examples of the drying method include reduced pressure drying, pressure drying, heat drying, and air drying. The heating temperature is preferably from 30 to 150°C, and more preferably from 40 to 120°C.

[0101] The method for producing the laminate 20 in FIG. 2 includes the above-mentioned steps (1) and (2) in this order. In step (1), for example, an ink composition is applied onto one surface of a plastic film 21 and dried to form a first printed layer 22. In step (2), for example, the water-based white ink composition of this embodiment is applied onto the surface of the first printed layer 22 opposite the plastic film 21 and dried to form a second printed layer 23. As in the method for producing the laminate 10, the kit of this embodiment may be used instead of the water-based white ink composition. The step (1) may be carried out once or twice or more, that is, the ink composition may be applied in multiple layers. The step (2) may be performed once or twice or more. That is, the water-based white ink composition or mixture (M) may be applied in multiple coats. As the coating method and drying method in steps (1) and (2), the same methods as those used in the production method of the laminate 10 can be applied.

[0102] <Application> The laminates 10 and 20 can be used as various labels such as plastic labels attached to packaging containers for beverages, foods such as prepared dishes and bento boxes, daily necessities such as cosmetics, etc. Among them, they are particularly suitable as labels for food and beverages. In particular, when the plastic films 11, 21 constituting the laminates 10, 20 are heat-shrinkable films, they are suitable as shrink labels.

[0103] <Action and effect> The laminate of the present embodiment described above has a printed layer (W) formed on one side of a plastic film using the water-based white ink composition or kit of the present invention described above, and therefore has excellent resistance to belt conveyor lubricants.

[0104] <Other embodiments> The laminate is not limited to the above-described embodiment. For example, in the case of the laminate 10 shown in Fig. 1, the printed layer 12 is provided over the entirety of one surface of the plastic film 11, but the printed layer 12 may also be provided over a portion of one surface of the plastic film 11. In this case, it is preferable that another printed layer is provided in the area of ​​one surface of the plastic film 11 where the printed layer 12 is not provided. Examples of the other printed layer include a layer formed from a varnish composition. Similarly, in the case of the laminate 20 shown in Fig. 2, the second printed layer 23 is provided on the entire one surface of the first printed layer 22, but the second printed layer 23 may be provided on a portion of one surface of the first printed layer 22. In this case, it is preferable that another printed layer is provided in the area on one surface of the first printed layer 22 where the second printed layer 23 is not provided. Examples of the other printed layer include a layer formed from a varnish composition.

[0105] 1, another printed layer may be provided on the surface of the printed layer 12 opposite to the plastic film 11. The other printed layer may be, for example, a layer formed from a varnish composition. Similarly, in the case of the laminate 20 shown in Fig. 2, another printed layer may be provided on the surface of the second printed layer 23 opposite to the first printed layer 22. The other printed layer may be, for example, a layer formed from a varnish composition.

[0106] [Labels, food and beverage labels] A label according to one embodiment of the present invention is obtained by using the laminate according to the present embodiment described above. A label for food and beverage according to one embodiment of the present invention is obtained by using the laminate according to this embodiment described above. As described above, the laminate of the present embodiment has a printed layer (W) formed on one side of a plastic film using the water-based white ink composition or kit of the present invention, and therefore has excellent resistance to belt conveyor lubricants. Therefore, the label and food and beverage label of the present embodiment obtained using the laminate having excellent resistance to belt conveyor lubricants also have excellent resistance to belt conveyor lubricants. EXAMPLES

[0107] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples as long as it does not depart from the gist of the present invention. In the following, "NV" stands for non-volatile content. It should be noted that Examples 5 to 7 and 11 to 13 are reference examples.

[0108] [Raw materials used] As the aqueous binder resin (A), the compound shown below was used. A-1: Acrylic resin emulsion (weight average molecular weight 291,000, glass transition temperature 9°C, minimum film formation temperature <5°C, acid value 38 mgKOH / g, non-volatile content 38.5% by mass). A-2: Acrylic resin emulsion (weight average molecular weight 215,000, glass transition temperature 25°C, acid value 78 mgKOH / g, non-volatile content 45.5% by mass). A-3: Acrylic resin emulsion (weight average molecular weight 218,000, glass transition temperature 14°C, acid value 52 mg KOH / g, non-volatile content 49% by mass). A-4: Acrylic resin emulsion (weight average molecular weight 71,000, glass transition temperature 75°C, acid value 82 mg KOH / g, non-volatile content 45% by mass). A-5: Water-soluble acrylic resin (manufactured by BASF Japan Ltd., product name "Joncryl 196", weight average molecular weight 9,200, glass transition temperature 85°C, acid value 200 mg KOH / g, non-volatile content 36% by mass). A-6: Acrylic urethane resin emulsion (manufactured by Taisei Fine Chemical Co., Ltd., product name "WEM-200U", glass transition temperature 27°C, acid value 16 mgKOH / g, non-volatile content 38% by mass). A-7: Urethane resin dispersion (Mitsui Chemicals, Inc., product name "WS-5000", non-volatile content 30% by mass).

[0109] As the water-repellent silicone (B), the compound shown below was used. B-1: Silicone modified copolymer (manufactured by EVONIK, product name "Tegoglide 482", non-volatile content 65% by mass). B-2: Amino-modified polydimethylsiloxane (manufactured by Shin-Etsu Chemical Co., Ltd., product name "KF-868", non-volatile content 100% by mass).

[0110] As titanium oxide (C), the compound shown below was used. C-1: Titanium oxide having a rutile crystal structure (manufactured by Ishihara Sangyo Kaisha, Ltd., product name "CR-90", oil absorption capacity 21 mL / 100 g, average particle size 0.25 μm, non-volatile content 100% by mass).

[0111] As optional components, the compounds shown below were used. Wax: Polyethylene wax (manufactured by Mitsui Chemicals, Inc., product name "Chemipearl W400", volume average particle size 4 μm, non-volatile content 40 mass%, hardness by needle penetration method 3, softening point by ring and ball method 110°C) Dispersant: A copolymer with affinity for pigments (manufactured by BYK, product name "DISPERBYK-190", non-volatile content 40% by mass). -pH adjuster: ammonia water. Antifoaming agent: A mixture of silicone and hydrophobic microparticles (manufactured by BYK, product name "BYK-094", non-volatile content 96% by mass). ·Thickener: Urethane associative thickener (manufactured by San Nopco Ltd., product name "SN Thickener 612", non-volatile content 40% by mass). ·D-1: Water.

[0112] As the curing agent (E), the following compound was used. E-1: Carbodiimide curing agent (manufactured by Nisshinbo Chemical Inc., product name "Carbodilite E-02", non-volatile content 40% by mass). E-2: Oxazoline-based curing agent (manufactured by Nippon Shokubai Co., Ltd., product name "Epocross WS-500", non-volatile content 39% by mass). E-3: Epoxy curing agent (manufactured by Nagase ChemteX, product name "Denacol EX-612", non-volatile content 99% by mass). E-4: Aziridine-based curing agent (manufactured by Nippon Shokubai, product name "Chemitite PZ-33", non-volatile content 99% by mass). E-5: Isocyanate-based curing agent (manufactured by Asahi Kasei, product name "Duranate WT30-100", non-volatile content 100% by mass).

[0113] [Evaluation method] <Evaluation of dispersibility> The water-based white ink compositions obtained in Examples 1 to 32 and Comparative Examples 1 to 7 were filled into a container and allowed to stand at 40°C for 30 days. Then, the presence or absence of precipitation of titanium oxide (C) was visually confirmed, and the dispersibility was evaluated according to the following evaluation criteria. ◯: No precipitation of titanium oxide (C) at all. △: Titanium oxide (C) settles slightly and soft caking is observed, but returns to normal when the container is shaken. ×: Titanium oxide (C) precipitated and hard caking was observed, and the mixture could not be restored by simply shaking the container.

[0114] <Measurement of water contact angle> Using the laminates (I) and laminates (II) obtained in Examples 1 to 32 and Comparative Examples 1 to 7, the water contact angle of the surface of the dried coating film (printed layer (W)) of the water-based white ink composition obtained in each example was measured in accordance with JIS R 3257:1999. A1: Water contact angle is less than 80°. A2: Water contact angle is 80° or more and less than 90°. A3: Water contact angle is greater than or equal to 90° and less than 95°. A4: Water contact angle is greater than 95° and less than 100°. A5: Water contact angle is between 100° and 110°. A6: Water contact angle is over 110°.

[0115] <Evaluation of resistance to belt conveyor lubricants (lubricant resistance)> 10 parts by mass of cetyltrimethylammonium bromide and 10 parts by mass of coconut alkyl dimethyl benzyl ammonium chloride as cationic surfactants, 10 parts by mass of LP-TEA (triethanolamine lauryl phosphate) as alkyl phosphate salt, 2 parts by mass of polyoxyethylene (10 moles) lauryl ether, and 68 parts by mass of water were placed in a dissolving tank and stirred to dissolve, to prepare a uniform lubricant for belt conveyors. An aqueous solution of this lubricant diluted 250 times with water was dropped onto the printed layer (W) of the laminates (I) and laminates (II) obtained in Examples 1 to 32 and Comparative Examples 1 to 7, and wiped off after one day, and the change in the appearance of the surface of the printed layer (W) was observed. Evaluation was performed according to the following criteria. ◎, ◯, or △ indicates practical use. ⊚: There is no change in the appearance of the printed layer (W). ◯: Thin drip marks remain on the printed layer (W). △: Drop marks are clearly visible on the printed layer (W). ×: Falling off of the printed layer (W) was observed.

[0116] <Evaluation of lamination> The same water-based white ink composition used for forming the second printed layer was applied to the surface opposite to the first printed layer of the second printed layer (printed layer (W)) of the laminates (II) obtained in Examples 1 to 32 and Comparative Examples 1 to 7 in such a manner that the coating amount after drying was 2.0 g / m 2 The coating was applied using a flexo hand proofer as an applicator so that the thickness of the coating was 100 μm or more. The coating was then dried for 1 minute with hot air from a dryer to form a third printed layer (printed layer (W)). The third printed layer (printed layer (W)) was visually inspected, and the lamination property was evaluated according to the following evaluation criteria. ◯: The ratio of the area of ​​the third printed layer to the area of ​​the second printed layer is 100%. Δ: The ratio of the area of ​​the third printed layer to the area of ​​the second printed layer is 80% or more. ×: The ratio of the area of ​​the third printed layer to the area of ​​the second printed layer is less than 80%.

[0117] <Evaluation of Adhesion> (Adhesion to PET film) An 18 mm wide cellophane tape (manufactured by Nichiban Co., Ltd.) was attached to the surface of the printed layer (W) of the laminates (I) and laminates (II) obtained in Examples 1 to 32 and Comparative Examples 1 to 7 and pressed with a finger. The cellophane tape was then quickly peeled off and the condition of the printed layer (W) remaining on the plastic film was visually confirmed. The adhesion of the printed layer (W) to the PET film was evaluated using the following evaluation criteria. The laminate (II) is a laminate of a plastic film / first printed layer / second printed layer (printed layer (W)). However, the first printed layer formed by flexographic printing is transferred to the plastic film in a dot pattern and spreads wet, so it does not cover the top of the plastic film without any gaps and there are gaps. Therefore, when the second printed layer (printed layer (W)) is printed on top of it, the second printed layer (printed layer (W)) is formed directly on the plastic film in the gaps of the first printed layer. In the above evaluation of adhesion using the laminate (II), an ink with good adhesion to the plastic film is used to form the first printed layer, so it can be determined that the adhesion of the second printed layer (printed layer (W)) to the plastic film is poor when the adhesion is poor. ⊚: The printed layer (W) was not peeled off at all. ◯: The ratio of the area of ​​the peeled printing layer (W) to the adhesive area of ​​the cellophane tape (peeling ratio) is more than 0% and less than 10%. Δ: The ratio of the area of ​​the peeled printed layer (W) to the adhesive area of ​​the cellophane tape (peeling ratio) is 10% or more and less than 30%. ×: The ratio of the area of ​​the peeled printed layer (W) to the adhesive area of ​​the cellophane tape (peeling ratio) is 30% or more.

[0118] (Adhesion to OPP film and PS film) Laminates (I) and (II) were prepared in the same manner as in Examples 1 to 32 and Comparative Examples 1 to 7, except that an OPP film (manufactured by Toyobo Co., Ltd., product name "Pylen P2161", thickness 30 μm) or a uniaxially shrinkable PS film (manufactured by Takiron C.I. Co., Ltd., product name "Bonset EPS45TD", thickness 40 μm) was used instead of the uniaxially shrinkable PET film. For the obtained laminate (I) and laminate (II), the adhesion of the printed layer (W) to the OPP film and the PS film was evaluated in the same manner as in the evaluation of the adhesion to the PET film.

[0119] [Examples 1 to 32, Comparative Examples 1 to 7] <Preparation of Water-Based White Ink Composition> According to the formulations shown in Tables 1 to 6, the aqueous binder resin (A), the water-repellent silicone (B), the titanium oxide (C), and optional components were mixed to obtain an aqueous white ink composition. The dispersibility of the resulting water-based white ink composition was evaluated, and the results are shown in Tables 1 to 6. Additionally, a blank cell in the table indicates that the component was not blended (amount blended: 0 parts by mass). NV in the table indicates the content of non-volatile matter relative to the total mass of each component. Tables 1 to 6 show the content of each component in the water-based white ink composition relative to the total mass of the non-volatile content of the water-based white ink composition.

[0120] For Examples 21 to 25, the mixture (M) was prepared by mixing 100 parts by mass of the obtained water-based white ink composition with the type and amount of the curing agent (E) shown in Table 4. In the case of Example 21, the ratio of the curing agent (E) to 100 parts by mass of the nonvolatile content of the water-based white ink composition was 3.1 parts by mass. In the case of Example 22, the ratio of the curing agent (E) to 100 parts by mass of the nonvolatile content of the water-based white ink composition was 3.0 parts by mass. In the case of Example 23, the ratio of the curing agent (E) to 100 parts by mass of the nonvolatile content of the water-based white ink composition was 3.1 parts by mass. In the case of Example 24, the ratio of the curing agent (E) to 100 parts by mass of the nonvolatile content of the water-based white ink composition was 3.1 parts by mass. In the case of Example 25, the ratio of the curing agent (E) to 100 parts by mass of the nonvolatile content of the water-based white ink composition was 3.4 parts by mass.

[0121] <Preparation of Laminate> (Preparation of Laminate (I)) As the plastic film, a uniaxially shrinkable PET film (manufactured by Toyobo Co., Ltd., product name "Toyobo Space Clean S7053", thickness 40 μm) was used. Cell volume 10.0cm 3 / m 2 The water-based white ink composition or mixture (M) of Examples 1 to 31 and Comparative Examples 1 to 7 was applied to one side of the plastic film using a flexographic hand proofer equipped with an anilox roll of 1.0 g / m2 as an applicator, so that the coating amount of the dried coating film was 2.0 g / m2. 2 The coating was then applied so that the resultant was: Next, the coating was dried for 1 minute with hot air from a dryer to form a printed layer (W), thereby obtaining a laminate (I) (printed matter) in which the printed layer (W) was laminated on the plastic film. The obtained laminate (I) was used to measure the water contact angle and to evaluate the resistance and adhesion to a belt conveyor lubricant. The results are shown in Tables 1 to 6.

[0122] (Preparation of Laminate (II)) As the plastic film, a uniaxially shrinkable PET film (manufactured by Toyobo Co., Ltd., product name "Toyobo Space Clean S7053", thickness 40 μm) was used. Cell volume 10.0cm 3 / m 2 A flexo hand proofer equipped with an anilox roll was used as an applicator to apply a urethane-based color ink (manufactured by Dainichi Seikagaku Kogyo Co., Ltd., product name "Hydrick FCF Series") to one side of the plastic film, with a coating weight of 1.0 g / m2 after drying. 2 The coating was then dried for 1 minute with hot air from a dryer to form a first printed layer (color printed layer (C)). Using the applicator, the water-based white ink composition or mixture (M) of Examples 1 to 31 and Comparative Examples 1 to 7 was applied to the side of the first printed layer opposite the plastic film so that the coating amount of the dried coating film was 2.0 g / m 2 The mixture was then dried for 1 minute with hot air from a dryer to form a second printed layer (printed layer (W)), thereby obtaining a laminate (II) (printed matter) in which the first printed layer (color printed layer (C)) and the second printed layer (printed layer (W)) were laminated in this order on the plastic film. In Example 32, a laminate (II) (printed matter) was obtained in the same manner, except that an acrylic color ink (manufactured by Dainichiseika Color & Chemicals Mfg. Co., Ltd., product name "Hydrick FCG Series") was used instead of the urethane color ink. The obtained laminate (II) was used to measure the water contact angle, and the resistance to a belt conveyor lubricant, lamination property, and adhesion were evaluated. The results are shown in Tables 1 to 6.

[0123] [Table 1]

[0124] [Table 2]

[0125] [Table 3]

[0126] [Table 4]

[0127] [Table 5]

[0128] [Table 6]

[0129] In the table, "Acrylic resin Em: water-soluble acrylic resin" is the mass ratio of the acrylic resin emulsion to the water-soluble acrylic resin in the water-soluble white ink composition. As is clear from the results of Tables 1 to 5, the printing layer (W) formed by the water-based white ink composition or mixture (M) obtained in each example was found to have excellent resistance to belt conveyor lubricants. In addition, according to Examples 26 to 31, it was found that the water contact angle increases and the resistance to belt conveyor lubricants improves as the content of water-repellent silicone (B) increases. On the other hand, it was found that the lamination property tends to decrease as the content of water-repellent silicone (B) increases.

[0130] On the other hand, as is clear from the results in Table 6, the printed layer (W) formed using the water-based white ink compositions obtained in Comparative Examples 1 to 6, which did not contain the water-repellent silicone (B), had a water contact angle of less than 90°, indicating that the printed layer (W) had poor resistance to belt conveyor lubricants. The printed layer (W) formed using the water-based white ink composition obtained in Comparative Example 7, which had a low content of water-repellent silicone (B), had a water contact angle of less than 90°, and was found to have poor resistance to belt conveyor lubricants. [Explanation of symbols]

[0131] 10 Laminate 11 Plastic Film 12 Printing layer (Printing layer (W)) 20 Laminate 21 Plastic Film 22 First printing layer (color printing layer (C)) 23 Second printing layer (printing layer (W))

Claims

1. An aqueous white ink composition for use on plastic labels of packaging containers for food and beverages, the composition comprising an aqueous binder resin, a water-repellent silicone, and titanium oxide, the aqueous binder resin comprises one or more selected from a water-soluble acrylic resin, an aqueous acrylic urethane resin, and an aqueous urethane resin; The aqueous white ink composition was applied to a printing object by flexographic printing in a coating amount of 2 g / m after drying. ２ The water-based white ink composition has a surface with a water contact angle of 90° or more when printed so that the surface of the dried coating film formed by printing is as follows:

2. 2. The water-based white ink composition according to claim 1, wherein the content of the water-repellent silicone is 0.1 mass % or more relative to the total mass of non-volatile components of the water-based white ink composition.

3. 2. The water-based white ink composition according to claim 1, wherein the surface of the dried coating film has a water contact angle of 90 to 110°.

4. 4. The water-based white ink composition according to claim 3, wherein the content of the water-repellent silicone is 0.1 to 1.8 mass % relative to the total mass of the non-volatile components of the water-based white ink composition.

5. The water-based white ink composition according to claim 1 for use with a curing agent.

6. A plastic film, a printed layer formed on one surface of the plastic film using the water-based white ink composition according to any one of claims 1 to 5; A laminate having

7. A plastic film, a first printed layer formed on one surface of the plastic film using an aqueous ink composition containing a color pigment; a second printed layer formed using the water-based white ink composition according to any one of claims 1 to 5 on the surface of the first printed layer opposite to the plastic film; A laminate having

8. A plastic label obtained using the laminate according to claim 6.

9. A plastic label obtained using the laminate according to claim 7.

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