JP2022166508A - Ink composition, laminate, and food packaging material - Google Patents

Abstract

To provide an ink composition that can form a printed layer having excellent anti-slip performance and blocking resistance, and is less likely to cause printing trouble, such as the attachment of ink to a guide roll, when used in gravure printing, a laminate including the ink composition, and a food packaging material.SOLUTION: An ink composition contains a binder resin (A), a hydrocarbon wax, a fatty acid amide, and a solvent. The binder resin (A) is at least one selected from the group consisting of a polyurethane resin, a cellulose resin, a polyester resin, and an acrylic resin. The hydrocarbon wax has a penetration of 7 or more. There are also provided: a laminate that includes a plastic substrate, and a printed layer that is disposed on the surface of the plastic substrate and composed of the ink composition; and a food packaging material formed from the laminate.SELECTED DRAWING: None

Description

The present invention relates to ink compositions, laminates, and food packaging materials.

BACKGROUND ART When a packaging material is produced using a base material such as a plastic film, printing with a printing ink such as gravure ink is performed for decoration and surface protection of the base material. Gravure printing is suitable for mass production because it enables high-definition and high-speed printing. However, from the viewpoint of improving the working environment, etc., there is a demand for the development of non-toluene-based solvent inks that do not contain toluene. In addition, there is a demand for an ink capable of printing high-quality images in order to respond to the diversification of packaging materials and the sophistication of packaging technology.

In addition to the printability of the ink itself, the film properties of the printed layer formed by the ink are important as the properties required for the ink such as gravure ink used for printing on film-like substrates. For the purpose of improving the film properties of the formed printed layer, for example, a gravure ink for surface printing containing a binder resin, a hydrocarbon wax, a chlorinated polyolefin, and a fatty acid amide has been proposed (Patent Document 1 ). Also, a gravure printing ink for lamination has been proposed that contains a binder resin, chlorinated polypropylene, polyethylene wax, and fatty acid amide (Patent Document 2). Furthermore, a gravure ink for forming a printed layer between two substrates has been proposed, which contains a binder resin, a chlorinated polyolefin resin, and a fatty acid amide (Patent Document 3).

JP 2019-59923 A Japanese Patent Application Laid-Open No. 2020-70396 JP 2018-184584 A

However, even with the gravure inks and the like proposed in Patent Documents 1 to 3, there are printing defects such as so-called "guide roll removal" in which ink or a coating film of ink that has fallen off adheres to the guide roll of the gravure printing machine. It was not always possible to sufficiently suppress the occurrence. In addition, it cannot be said that the blocking resistance of the formed ink layer is necessarily sufficient, and there is room for further improvement. Furthermore, when food packaging materials such as rice bags manufactured using conventional ink as surface printing ink, for example, are stacked, they are slippery, making it difficult to store and transport large quantities.

The present invention has been made in view of the problems of the prior art, and an object of the present invention is to provide a gravure printing method capable of forming a printing layer having excellent anti-slip properties and anti-blocking properties. To provide an ink composition which hardly causes printing problems such as guide roll pick-up even when used for printing. Another object of the present invention is to provide a laminate and a food packaging material using this ink composition.

That is, according to the present invention, the following ink composition is provided.
[1] containing a binder resin, a hydrocarbon wax, a fatty acid amide, and a solvent, wherein the binder resin is at least one selected from the group consisting of polyurethane resins, cellulose resins, polyester resins, and acrylic resins; An ink composition in which a hydrogen wax has a penetration of 7 or more.
[2] The ink composition according to [1] above, wherein the hydrocarbon wax has an average particle size of 5 μm or less.
[3] Further containing at least one adhesion-assisting resin selected from the group consisting of maleic acid-modified resins, rosin-modified resins, ketone resins, and chlorinated polyolefin resins, the adhesion-assisting resin per 100 parts by mass of the binder resin. The ink composition according to [1] or [2], wherein the content of is 1 to 50 parts by mass.
[4] The ink composition according to any one of [1] to [3], wherein the binder resin is a polyurethane resin and a cellulose resin.
[5] The ink composition according to any one of [1] to [4], further comprising resin beads having an average particle size of 2 μm or less.
[6] The ink composition according to any one of [1] to [5], further containing a chelating agent.
[7] The ink composition according to any one of [1] to [6], further containing a plasticizer.
[8] The ink composition according to any one of [1] to [7], which does not substantially contain toluene.

Further, according to the present invention, the following laminate and food packaging material are provided.
[9] A laminate comprising a plastic substrate and a printed layer formed of the ink composition according to any one of [1] to [8] and disposed on the surface of the plastic substrate. .
[10] A food packaging material formed from the laminate according to [9].

According to the present invention, there is provided an ink composition capable of forming a printed layer having excellent anti-slip properties and anti-blocking properties, and which hardly causes printing problems such as guide roll removal even when used in gravure printing. be able to. Further, according to the present invention, it is possible to provide a laminate and a food packaging material using this ink composition.

<Ink composition>
Embodiments of the present invention will be described below, but the present invention is not limited to the following embodiments. An ink composition (hereinafter also simply referred to as "ink") which is one embodiment of the present invention contains a binder resin, a hydrocarbon wax, a fatty acid amide, and a solvent, and is suitable as a surface printing ink for gravure printing, for example. It is an ink composition. Details of the ink composition of the present embodiment will be described below.

(binder resin)
A binder resin is a component that functions as a binder resin for forming a printed layer (image) formed by ink applied to a substrate. The ink composition of the present embodiment contains at least one binder resin selected from the group consisting of polyurethane resins, cellulose resins, polyester resins, and acrylic resins. The binder resin preferably contains two or more resins. Among them, the binder resin is preferably polyurethane resin and cellulose resin. By using these two resins together, it is possible to further improve the anti-slip properties of the printed layer formed, and to further improve the physical properties of the printed layer (ink film) such as blocking resistance and scratch resistance. can. The content of the binder resin in the ink composition may generally be about 3 to 60% by mass based on the total ink composition, and may be appropriately set according to the application.

Examples of polyurethane resins include polyether polyurethane resins containing structural units derived from polyether polyols, and polyester polyols containing structural units derived from polyester polyols. Among them, it is preferable to use a polyether-based polyurethane resin because it can more effectively suppress plate clogging and plate fogging. In the polyether-based polyurethane resin, the content of structural units derived from polyether polyol is preferably 5 to 80% by mass, more preferably 10 to 60% by mass, and 10 to 50% by mass. is particularly preferred. In the polyester-based polyurethane resin, the content of structural units derived from polyester polyol is preferably 5 to 80% by mass, more preferably 10 to 60% by mass, and 10 to 50% by mass. is particularly preferred.

A polyurethane resin can be produced by a conventionally known method. For example, a polyurethane resin composed of a polyol and a polyisocyanate, or a polyurethane resin obtained by reacting an isocyanate-terminated urethane prepolymer composed of a polyol and a polyisocyanate with a chain extender, and the like are preferable.

Examples of polyols include polyether polyols, polyester polyols, polycaprolactone polyols, polycarbonate polyols, polyolefin polyols, castor oil polyols, hydrogenated castor oil polyols, dimer diols, and hydrogenated dimer diols.

Examples of polyether polyols include polypropylene glycol, polyethylene glycol, polytetramethylene glycol, polytrimethylene glycol and the like. The polyether polyol preferably has a number average molecular weight of 200 to 5,000. The number average molecular weight is a value calculated from the hydroxyl value when terminal hydroxyl groups are used.

Examples of polyester polyols include condensates obtained by an esterification reaction between a dibasic acid and a diol. Dibasic acids include adipic acid, phthalic anhydride, isophthalic acid, terephthalic acid, maleic acid, fumaric acid, succinic acid, oxalic acid, malonic acid, pimelic acid, azelaic acid, sebacic acid, suberic acid, glutaric acid, 1 ,4-cyclohexyldicarboxylic acid, dimer acid, hydrogenated dimer acid and the like. Diols include ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,3-butanediol, 1,6-hexanediol and 1,8-octanediol. , 1,9-nonanediol, neopentyl glycol, 3-methyl-1,5-pentanediol, 2-methyl-1,3-propanediol, 3,3,5-trimethylpentanediol, 2,4-diethyl- 1,5-pentanediol, 1,12-octadecanediol, 1,2-alkanediol, 1,3-alkanediol, 1-monoglyceride, 2-monoglyceride, 1-monoglycerol ether, 2-monoglycerol ether, dimer diol , hydrogenated dimer diol and the like. The polyester polyol preferably has a number average molecular weight of 200 to 5,000.

Examples of polyisocyanates include aromatic diisocyanates, aliphatic diisocyanates, and alicyclic diisocyanates. Examples of aromatic diisocyanates include 4,4'-diphenylmethane diisocyanate (MDI), 4,4'-dibenzylisocyanate, 1,3-phenylene diisocyanate, tolylene diisocyanate, and xylylene diisocyanate. Examples of aliphatic diisocyanates include ethylene diisocyanate, butane-1,4-diisocyanate and hexamethylene diisocyanate. Examples of the alicyclic diisocyanate include isophorone diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, 1,3-bis(isocyanatomethyl)cyclohexane, hydrogenated xylylene diisocyanate, methylcyclohexane diisocyanate, norbornane diisocyanate and the like.

Examples of chain extenders include diamine-based chain extenders and polyfunctional amine-based chain extenders. Examples of diamine-based chain extenders include ethylenediamine, propylenediamine, hexamethylenediamine, pentamethylenediamine, isophoronediamine, dicyclohexylmethane-4,4'-diamine, and p-phenylenediamine.

Cellulose resins include cellulose ester resins such as cellulose acetate propionate and cellulose acetate butyrate; nitrocellulose; hydroxyalkylcellulose; carboxyalkylcellulose; The cellulose ester resin preferably has an alkyl group such as methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, pentyl group and hexyl group. As the cellulose resin, cellulose acetate propionate, cellulose acetate butyrate, and nitrocellulose (nitrocellulose) are preferred, and nitrocellulose (nitrocellulose) is particularly preferred. The weight average molecular weight of the cellulose resin is preferably 5,000 to 200,000, more preferably 10,000 to 50,000.

Nitrocellulose is usually a nitric acid ester obtained by reacting natural cellulose with nitric acid, in which three hydroxyl groups in natural cellulose are substituted with nitric acid groups. The average degree of polymerization of nitrocellulose is preferably 20-200, more preferably 30-150. The nitrogen content of nitrocellulose is usually about 10.5 to 12.5% by mass.

Moreover, it is preferable to use a cellulose ester resin and an acrylic resin in combination, because it is possible to form a printed layer that is excellent in fitting onto the surface of a molded article made of polyester such as a PET bottle. Therefore, an ink composition containing a cellulose ester resin and an acrylic resin as a binder resin is suitable as a reverse printing ink for a shrink film placed on the surface of a PET bottle or the like.

(hydrocarbon wax)
The ink composition contains a hydrocarbon wax having a penetration (hardness) of 7 or more, preferably 10 or more, more preferably 12 or more at 25° C. defined in JIS K 2207. By containing a hydrocarbon wax having a penetration within the above range, the coefficient of friction of the printed layer (ink film) to be formed is increased, and anti-slip properties can be enhanced.

Hydrocarbon waxes include polyethylene wax, Fischer-Tropsch wax, paraffin wax, microstaline wax, polypropylene wax and the like. Among them, polyethylene wax and Fischer-Tropsch wax are preferred. The content of the hydrocarbon wax in the ink composition is preferably 0.05 to 5% by mass, more preferably 0.1 to 3% by mass, more preferably 0.1 to 3% by mass, based on the total ink composition. 15 to 2% by mass is particularly preferred.

Examples of polyethylene wax include high-density polymerized polyethylene, low-density polymerized polyethylene, oxidized polyethylene, acid-modified polyethylene, special monomer-modified polyethylene, and the like. Fischer-Tropsch wax is a wax produced by the Fischer-Tropsch process using carbon monoxide and hydrogen as raw materials, and has a nearly saturated linear molecular structure without branching.

The average particle size of the hydrocarbon wax is preferably 5 μm or less, more preferably 0.5 to 5 μm, particularly preferably 1 to 4.5 μm. By using a hydrocarbon wax having an average particle diameter within the above range, for example, when performing gradation printing, dot dropout such as white voids is less likely to occur, resulting in favorable plate tone transition. Furthermore, sediments are less likely to occur even when stored under conditions such as being subjected to a heat cycle, and ink stability can be enhanced. The average particle size of the hydrocarbon wax is a volume-based cumulative 50% particle size (median size (D50)) measured by a laser diffraction/light scattering method.

(Fatty acid amide)
The ink composition contains fatty acid amides. By containing the fatty acid amide, the blocking resistance of the formed printed layer (ink film) can be improved. As fatty acid amides, those having an aliphatic hydrocarbon group having 10 to 25 carbon atoms and an amide group are preferred. Specific examples of fatty acid amides include lauric acid amide, palmitic acid amide, stearic acid amide, behenic acid amide, hydroxystearic acid amide, oleic acid amide, and erucic acid amide. The content of the fatty acid amide in the ink composition is preferably 0.1 to 2% by mass, more preferably 0.2 to 1.5% by mass, based on the total ink composition. .3 to 0.7% by mass is particularly preferred.

(solvent)
The ink composition contains a solvent such as an organic solvent. Examples of organic solvents include aromatic organic solvents such as toluene and xylene; ketone organic solvents such as methyl ethyl ketone and methyl isobutyl ketone; ester organic solvents such as ethyl acetate, n-propyl acetate, isopropyl acetate and isobutyl acetate; Alcohol organic solvents such as ethanol, n-propanol, isopropanol and n-butanol; glycol ether solvents such as ethylene glycol monopropyl ether and propylene glycol monomethyl ether; and the like can be used.

Among them, an organic solvent (non-toluene organic solvent) that does not substantially contain an aromatic organic solvent such as toluene or xylene is preferable. That is, the ink composition is preferably a non-toluene ink that does not substantially contain toluene from an environmental point of view. As the solvent, it is preferable to use a mixed organic solvent containing an ester-based organic solvent and an alcohol-based organic solvent at a weight ratio of 50:50 to 90:10.

(Adhesion auxiliary resin)
The ink composition preferably further contains at least one adhesion assisting resin selected from the group consisting of maleic acid-modified resins, rosin-modified resins, ketone resins, and chlorinated polyolefin resins. By containing these adhesion-assisting resins, the adhesion of the printed layer formed from the ink composition to various substrates can be improved. Among them, maleic acid-modified resin, rosin-modified resin, and chlorinated polyolefin resin are preferably used as the adhesion-assisting resin.

The content of the adhesion assisting resin in the ink composition is preferably 1 to 50 parts by mass, more preferably 5 to 45 parts by mass, more preferably 7.5 to 40 parts by mass, based on 100 parts by mass of the binder resin. Part by weight is particularly preferred, and 10 to 30 parts by weight is most preferred. By setting the content of the adhesion-assisting resin within the above range, the adhesion of the printed layer to various substrates can be further enhanced.

Examples of the maleic acid-modified resin include styrene-maleic acid resin, polyolefin-maleic acid resin, vinyl chloride-vinyl acetate-maleic acid copolymer resin, and the like. As the rosin-modified resin, it is preferable to use rosin-modified maleic acid resin, rosin ester, rosin phenol, polymerized rosin, and the like. Among them, it is preferable to use a rosin-modified resin having a softening point of 90 to 200° C. as measured by the ring and ball method, since the blocking resistance of the printed layer can be further improved. Also, it is preferable to use the rosin-modified resin together with the polyurethane resin. The content of the maleic acid-modified resin in the ink composition is preferably 1 to 50 parts by mass, more preferably 5 to 35 parts by mass, more preferably 7.5 to 7.5 parts by mass, based on 100 parts by mass of the binder resin. 25 parts by weight is particularly preferred, and 10 to 20 parts by weight is most preferred.

A chlorinated polyolefin resin is a polyolefin resin in which at least part of hydrogen atoms are substituted with chlorine atoms. The weight average molecular weight of the chlorinated polyolefin is preferably from 5,000 to 100,000 because it has good compatibility with the binder resin and good affinity with the hydrocarbon wax. A chlorine content of 25 to 45% by mass in the chlorinated polyolefin resin is preferable because the adhesion of the printed layer to the substrate is further improved. The chlorine content of the chlorinated polyolefin resin is the content of chlorine atoms (% by mass) in the chlorinated polyolefin resin. The content of the chlorinated polyolefin resin in the ink composition is 0.5 to 20 parts by mass with respect to 100 parts by mass of the binder resin, from the viewpoint of the balance between the blocking resistance and the adhesion of the printed layer to the substrate. It is preferably 1.0 to 10 parts by mass, particularly preferably 2.0 to 7.5 parts by mass, and most preferably 3.0 to 5.0 parts by mass. .

As the polyolefin resin constituting the chlorinated polyolefin resin, homopolymers or copolymers of α-olefin unsaturated hydrocarbons such as polypropylene, poly-1-butene and poly-4-methyl-1-pentene are preferable. Polypropylene is more preferred. That is, chlorinated polypropylene is preferable as the chlorinated polyolefin resin. By using chlorinated polypropylene and hydrocarbon wax together, the adhesion of the printed layer to various substrates can be synergistically improved.

(resin beads)
The ink composition preferably further contains resin beads. By containing the resin beads, it is possible to improve the plate tone transition. Also, the average particle size of the resin beads is preferably 0.5 μm or more and 2 μm or less. By containing resin beads having an average particle size within this range, it is possible to improve plate tone transition and further improve ink stability. The average particle size of the resin beads is a volume-based cumulative 50% particle size (median size (D50)) measured by a laser diffraction/light scattering method.

The content of resin beads in the ink composition is generally 0.05 to 0.5% by mass, preferably 0.07 to 0.2% by mass, based on the total ink composition. Examples of resin beads that can be used include acrylic resin beads, urethane resin beads, benzoguanamine resin beads, melamine resin beads, silicone resin beads, and the like.

(pigment)
The ink composition may contain a pigment. A colorless ink composition that does not substantially contain a coloring material such as a pigment may be used.

As pigments, extender pigments, inorganic pigments, organic pigments, and the like can be used. Examples of extender pigments include silica, barium sulfate, kaolin, clay, calcium carbonate and magnesium carbonate. Inorganic pigments include white inorganic pigments such as titanium oxide, zinc oxide, zinc sulfide, barium sulfate, calcium carbonate, chromium oxide, and silica; black inorganic pigments such as carbon black and iron black; aluminum particles, mica, bronze powder, and chromium. Vermilion, yellow lead, cadmium yellow, cadmium red, ultramarine blue, Prussian blue, red iron oxide, yellow iron oxide, zinc oxide, and other inorganic pigments of various colors;

Examples of organic pigments include soluble azo, insoluble azo, azo, phthalocyanine, halogenated phthalocyanine, anthraquinone, anthanthrone, dianthraquinonyl, anthrapyrimidine, perylene, perinone, quinacridone, Examples include thioindigo-based, dioxazine-based, isoindolinone-based, quinophthalone-based, azomethineazo-based, flavanthrone-based, diketopyrrolopyrrole-based, isoindoline-based, and indanthrone-based organic pigments.

The content of the pigment in the ink composition may be set to an amount sufficient to ensure the coloring power and the like of the ink. Specifically, the content of the pigment in the ink composition is usually 1 to 50% by mass based on the total ink composition.

(Additive)
The ink composition can further contain various additives. Additives include pigment derivatives, dispersants, plasticizers, wetting agents, adhesion aids, leveling agents, antifoaming agents, antistatic agents, viscosity modifiers, chelating agents, trapping agents, antiblocking agents, and the aforementioned hydrocarbons. Wax components other than wax, cross-linking agents, silane coupling agents, and the like can be used.

By including a chelating agent in the ink composition, it is possible to further improve adhesion to plastic substrates and the like, and to form a printed layer with improved strength. As the chelating agent, it is preferable to use a titanium chelate. Titanium chelating agents include titanium alkoxides such as tetraisopropyl titanate, tetra-normal-butyl titanate, butyl titanate dimer, tetra(2-ethylhexyl) titanate, tetramethyl titanate, tetrastearyl titanate; triethanolamine titanate, titanium acetylacetate toner; titanium tetraacetylacetonate, tetraisopropoxytitanium, titanium ethylacetoacetate, titanium lactate, octylene glycol titanate, titanium n-butyl phosphate, propanediox titanium bis(ethylacetylacetate), and the like.

The content of the chelating agent in the ink composition is preferably 0.1 to 5% by mass, more preferably 0.5 to 2% by mass, based on the total ink composition. By setting the content of the chelating agent within the above range, the ink stability can be further improved, and the heat resistance, oil resistance, and blocking resistance of the formed printed layer can be further improved.

(Production of ink composition)
The ink composition can be produced by a conventionally known method. For example, it can be produced by dissolving or dispersing a binder resin, hydrocarbon wax, or the like in a solvent. Physical properties such as viscosity of the ink composition can be adjusted by appropriately controlling the size and filling rate of the media used in the dispersing machine, the dispersion treatment time, and the like. The hydrocarbon wax is preferably finely dispersed in the solvent in advance and added during the manufacturing process. As a dispersing machine, a roller mill, ball mill, pebble mill, attritor, sand mill, or the like can be used.

<Laminate>
A laminate, which is one embodiment of the present invention, is a so-called printed material comprising a plastic substrate and a printed layer formed of the ink composition described above and disposed on the surface of the plastic substrate. The laminate of the present embodiment can be produced, for example, by printing an ink composition on a plastic substrate and then removing volatile components to form a printed layer. Examples of the printing method include gravure printing and flexible printing. Especially, it is preferable to print by gravure printing. After diluting the ink composition with a diluting solvent so as to have a viscosity and concentration suitable for gravure printing, the ink composition is supplied to a printing unit of a gravure printing machine and applied onto a plastic film. After that, by drying in an oven or the like to form a printed layer (film) and fixing it, a laminate can be obtained.

A film-like or sheet-like base material can be used as the plastic base material. Examples of plastics constituting the base material include polyolefin resins such as polyethylene and polypropylene; polyester resins such as polyethylene terephthalate, polycarbonate, and polylactic acid; polystyrene resins such as polystyrene, AS resin, and ABS resin; polyamide resins; vinylidene chloride; cellophane; and the like.

The plastic substrate may be corona treated or untreated. Also, the plastic substrate may be stretched or unstretched. Metals or metal oxides such as silica, alumina, and aluminum may be vapor-deposited on the plastic substrate, and the vapor-deposited surface may be coated with a paint such as polyvinyl alcohol.

<Food packaging materials>
A food packaging material, which is one embodiment of the present invention, is formed of the laminate described above. The laminate constituting the food packaging material of the present embodiment is a printed matter in which a printed layer having excellent anti-slip properties and anti-blocking properties formed from the ink composition described above is provided on the surface of a plastic substrate. . For this reason, the food packaging material of the present embodiment is often stacked and stored or transported in large quantities. It is suitable as

EXAMPLES The present invention will be specifically described below based on Examples, but the present invention is not limited to these Examples. "Parts" and "%" in Examples and Comparative Examples are based on mass unless otherwise specified.

<Preparation of each component>
Each component shown below was prepared.
(binder resin)
・Nitrocellulose (nitrocellulose): Product name “DHX30-50”, manufactured by Nobel ・Polyether-based polyurethane resin: Product name “Seikabond A-154”, manufactured by Dainichiseika Kogyo Co., Ltd. ・Polyester-based polyurethane resin: Product name “ Seikabond E-263", manufactured by Dainichiseika Kogyo Co., Ltd. Polyester resin: trade name "Vylon 200", manufactured by Toyobo Acrylic resin: trade name "Dianal BR-106", manufactured by Mitsubishi Rayon Co., Ltd. Cellulose ester resin: cellulose Acetate butyrate, trade name "CAB-381-0.5", manufactured by Eastman Chemical Co.

(Adhesion auxiliary resin)
・Styrene-maleic acid resin: product name “Alastor 700”, manufactured by Arakawa Chemical Industries, Ltd. ・Chlorinated PP: chlorinated polypropylene, product name “Superchron 814HS”, manufactured by Nippon Paper Industries Co., Ltd. ・Rosin derivative: product name “Foral AX” , manufactured by Yamaso Kagaku Co., Ltd.

(hydrocarbon wax)
・Wax A: low-density polyethylene wax, trade name "Hi-Wax 220P", manufactured by Mitsui Chemicals, penetration 13, average particle size 2 μm, 4 μm, 6 μm
・Wax B: Oxidized polyethylene wax, trade name "High Wax 220MP", manufactured by Mitsui Chemicals, Penetration 14, average particle size 2 µm, 6 µm
・Wax C: low-density polyethylene wax, trade name “Hi-Wax 320P”, manufactured by Mitsui Chemicals, penetration 7, average particle size 2 μm
・Wax D: high-density polyethylene wax, trade name "Hi-Wax 400P", manufactured by Mitsui Chemicals, Penetration <1, average particle size 2 µm, 4 µm
・Wax E: Oxidized polyethylene wax, trade name "Hi-Wax 310MP", manufactured by Mitsui Chemicals, Penetration 3, Average particle size 2 µm

(Fatty acid amide)
・ Erucamide: trade name “Neutron S”, manufactured by Nippon Fine Chemical Co., Ltd. ・ Stearic acid amide: trade name “Neutron-2” manufactured by Nippon Fine Chemical Co., Ltd.

(resin beads)
・ Acrylic resin beads A: trade name “MR-1HG”, manufactured by Soken Chemical Co., Ltd., average particle size 1 μm
・Acrylic resin beads B: Trade name “Eposter MA2001” manufactured by Nippon Shokubai Co., Ltd., average particle size 3 μm
・ Acrylic resin beads C: trade name “Techpolymer MBX-5”, manufactured by Sekisui Plastics Co., Ltd., average particle size 5 μm
・Benzoguanamine resin beads: trade name “Eposter MS” manufactured by Nippon Shokubai Co., Ltd., average particle size 2 μm
・ Urethane resin beads: trade name “Dymic Beads UCN-5030D”, manufactured by Dainichiseika Kogyo Co., Ltd., average particle size 3 μm

(pigment)
・Titanium oxide: product name “Titanics JR-701”, manufactured by Tayca ・Copper phthalocyanine blue: product name “ZCA-350EP”, manufactured by Dainichiseika Kogyo Co., Ltd.

(other ingredients)
・Plasticizer A: Product name “Topsizer”, manufactured by Fuji Amido Chemical Co., Ltd. ・Plasticizer B: Product name “ATBC”, manufactured by Asahi Kasei ・Antifoaming agent: Product name “BYK-054”, manufactured by BYK ・Titanium chelate Agent: trade name “Orgatics TC-100”, manufactured by Matsumoto Fine Chemical Co., Ltd. ・Polymer dispersant: trade name “Solsperse”, manufactured by Lubrizol ・Silicon: trade name “KP-357”, manufactured by Shin-Etsu Silicon Co., Ltd. ・Solvent: Ethyl acetate (EAC), normal propyl acetate (NPAC), isopropyl alcohol (IPA), methylcyclohexane (MCH) (EAC/NPAC/IPA/MCH = 50/30/15/5)

<Preparation of ink composition>
(Example 1)
4.4 parts of nitrocellulose, 6.7 parts of polyether-based polyurethane resin, 1.9 parts of styrene-maleic acid resin, 0.2 parts of wax A (2 μm), 0.4 parts of erucamide, acrylic resin beads A0. 1 part, 23.8 parts of titanium oxide, 0.5 parts of chlorinated PP, 0.9 parts of plasticizer A, 1.4 parts of plasticizer B, 0.02 parts of antifoaming agent, 1.2 parts of titanium chelating agent, and 58 parts of solvent .5 parts were mixed and well dispersed using a paint shaker to give an ink composition (Example 1 (white ink)).

(Examples 2 to 17, Comparative Examples 1 to 5)
Ink compositions (Examples 2-10 and 12-16 ( white ink), Comparative Examples 1 to 4 (white ink), Example 11 (blue ink), Example 17 and Comparative Example 5 (colorless ink)).

<Evaluation>
A gravure printing machine equipped with a Helio 175 line/inch gravure engraving plate was used to apply each prepared ink composition to each substrate shown below to produce prints.
・OPP: Biaxially oriented polypropylene (OPP) film with corona discharge treatment on one side, thickness 25 μm
・PET: polyethylene terephthalate (PET) film, thickness 12 μm
OPS: Shrink biaxially oriented polystyrene (OPS) film, thickness 30 μm

(Substrate adhesion)
A cellophane tape (trade name “Cellotape (registered trademark)”, manufactured by Nichiban Co., Ltd., width 18 mm) is attached to the printed surface of the manufactured printed matter, and then an adhesion test is performed, and each base material is peeled off according to the evaluation criteria shown below. The adhesion of the image to the surface was evaluated. Results are shown in Tables 3 and 4.
○: No ink film was removed on the cellophane tape side ×: The ink film was entirely removed on the cellophane tape side

(plate change)
After applying white ink to the OPP film and printing a solid image with a gravure engraving plate of 175 lines, gradation printing was performed with a gravure engraving plate of 10 to 90% gradation with 175 lines and further applying blue ink. As the blue ink, trade name "NB300 739 Indigo" (manufactured by Dainichiseika Kogyo Co., Ltd.) was used. The presence or absence of missing dots in the highlighted portions to which the blue ink was applied was visually checked, and the plate tone transfer was evaluated according to the following evaluation criteria. Results are shown in Tables 3 and 4.
◎: No missing cells at 20% of gradation, missing cells at 10% ○: No missing cells at 30% of gradation, missing cells at 20% ×: Missing cells from 40% of gradation

(Coefficient of friction)
The printed surfaces of the printed matter produced by applying the ink composition (white ink and blue ink) to the OPP film are overlapped, and the static friction coefficient and dynamic friction coefficient are measured by sliding with JIS K7125 (200 g load, 100 mm / min). did. Results are shown in Tables 3 and 4.

(Coefficient of friction (OPS))
The static friction coefficient and the dynamic friction coefficient were measured by overlaying a PET film on the printed surface of a printed matter produced by applying an ink composition (colorless ink) to an OPS film and sliding it under JIS K7125 (200 g load, 100 mm/min). . Table 4 shows the results.

(Blocking resistance)
Printed matter produced by applying an ink composition to an OPP film (Examples 1 to 14, Comparative Examples 1 to 5), printed matter produced by applying an ink composition to a PET film (Example 15, Comparative Example 6), and printed matter (Example 16, Comparative Example 7) produced by applying the ink composition to the OPS film, and the printed surfaces immediately after printing were overlapped.
After being stored for 48 hours in a constant temperature bath at 40° C. under a load of 7 kg/cm ² , the presence or absence of adhesion between the printed surfaces was checked, and the blocking resistance was evaluated according to the evaluation criteria shown below. Table 4 shows the results.
◎: Peelable without resistance ○: There is a slight peeling resistance, but the ink is not removed from the opposite side △: There is peeling resistance ×: There is ink removal

(Ink stability)
Each ink composition was filled in a 300 mL closed container. After 2 weeks of heat cycles at 0° C.×12 hours and 40° C. for 12 hours, the sedimentation state was visually observed and the sedimentation state was confirmed, and the ink stability was evaluated according to the evaluation criteria shown below. Results are shown in Tables 3 and 4.
○: Separation, no sedimentation △: No separation, sedimentation ×: Separation, sedimentation

(guide roll taken)
After printing, the presence or absence of adhesion of ink or ink coating film to the guide roll of the gravure printing machine was visually confirmed, and "guide roll removal" was evaluated according to the evaluation criteria shown below. Results are shown in Tables 3 and 4.
○: No loose guide roll ×: Loose guide roll

(plate jam)
Print at a printing speed of 50 m / min with a gradation plate of 175 lines and 10 to 90% gravure engraving plate, check the amount of ink transfer in the highlight part after printing for 60 minutes from the start of printing, and follow the evaluation criteria shown below. plate clogging” was evaluated. Table 3 shows the results.
○: No change in the amount of ink transfer at the 10% gradation point between the start of printing and 60 minutes after printing △: No change in the amount of ink transfer at the 20% gradation point at the start of printing and after 60 minutes ×: The amount of ink transfer at the 30% gradation point is unchanged at the start of printing and after 60 minutes

(plate fogging)
The degree of contamination of the non-printing portion of the produced printed matter was visually confirmed, and "plate fogging" was evaluated according to the evaluation criteria shown below. Table 3 shows the results.
○: No ink transfer to non-printing area △: Slight ink transfer to non-printing area ×: Ink transfer to non-printing area

The ink composition of the present invention is suitable as a surface printing gravure ink or a back printing gravure ink for printing on plastic substrates (films) constituting various packaging materials such as food packaging materials.

That is, according to the present invention, the following ink composition is provided.
[1] containing a binder resin, a hydrocarbon wax, a fatty acid amide, and a solvent, wherein the binder resin is at least one selected from the group consisting of polyurethane resins, cellulose resins, polyester resins, and acrylic resins; An ink composition in which a hydrogen wax has a penetration of 12 or more.
[2] The ink composition according to [1], wherein the hydrocarbon wax has a penetration of 13 or more.
[3] The ink composition according to [1] or [2], further comprising resin beads other than the hydrocarbon wax, having an average particle size of 2 μm or less.
[4] It contains a binder resin, a hydrocarbon wax, a fatty acid amide, and a solvent, and further contains resin beads having an average particle size of 2 μm or less other than the hydrocarbon wax, and the binder resin is a polyurethane resin or cellulose. An ink composition comprising at least one selected from the group consisting of resins, polyester resins and acrylic resins, wherein the hydrocarbon wax has a penetration of 7 or more.
[5] The above [3] or [4], wherein the resin beads are at least one selected from the group consisting of acrylic resin beads, urethane resin beads, benzoguanamine resin beads, melamine resin beads, and silicone resin beads. ink composition.
[ 6 ] The ink composition according to any one of [1] to [5], wherein the hydrocarbon wax has an average particle size of 5 μm or less.
[ 7 ] Further containing at least one adhesion-assisting resin selected from the group consisting of maleic acid-modified resins, rosin-modified resins, ketone resins, and chlorinated polyolefin resins, the adhesion-assisting resin per 100 parts by mass of the binder resin The ink composition according to any one of [1] to [6], wherein the content of is 1 to 50 parts by mass.
[ 8 ] The ink composition according to any one of [1] to [ 7 ], wherein the binder resin is a polyurethane resin and a cellulose resin .
[9 ] The ink composition according to any one of [1] to [ 8 ], further containing a chelating agent.
[ 10 ] The ink composition according to any one of [1] to [ 9 ], further containing a plasticizer.
[ 11 ] The ink composition according to any one of the above [1] to [ 10 ], which is substantially free of toluene.

Further, according to the present invention, the following laminate and food packaging material are provided.
[ 12 ] A laminate comprising a plastic substrate and a printed layer formed of the ink composition according to any one of [1] to [ 11 ], provided on the surface of the plastic substrate. .
[ 13 ] A food packaging material formed of the laminate according to [ 12 ].

(Examples 2-7, 12-15, Reference Examples 8-11, 16, 17, Comparative Examples 1-5)
Ink compositions (Examples 2 to 7, Reference Examples 8 to 10 and Examples 12 to 15, Reference Example 16 (white ink), Comparative Examples 1 to 4 (white ink), Reference Example 11 (blue ink), Reference Example 17 and Comparative Example 5 (colorless ink)).

(Blocking resistance)
Printed matter produced by applying ink composition to OPP film (Examples 1 to 7, 12 to 14, Reference examples 8 to 11, Comparative examples 1 to 5), printed matter produced by applying ink composition to PET film (Example 15, Comparative Example 6) and printed matter produced by applying the ink composition to an OPS film ( Reference Example 16, Comparative Example 7) were overlapped immediately after printing.
After being stored for 48 hours in a constant temperature bath at 40° C. under a load of 7 kg/cm ² , the presence or absence of adhesion between the printed surfaces was checked, and the blocking resistance was evaluated according to the evaluation criteria shown below. Table 4 shows the results.
◎: Peelable without resistance ○: There is a slight peeling resistance, but the ink is not removed from the opposite side △: There is peeling resistance ×: There is ink removal

Claims (10)

containing a binder resin, a hydrocarbon wax, a fatty acid amide, and a solvent;
The binder resin is at least one selected from the group consisting of polyurethane resins, cellulose resins, polyester resins, and acrylic resins,
The ink composition, wherein the hydrocarbon wax has a penetration of 7 or more. 2. The ink composition according to claim 1, wherein the hydrocarbon wax has an average particle size of 5 [mu]m or less. further containing at least one adhesion-assisting resin selected from the group consisting of maleic acid-modified resins, rosin-modified resins, ketone resins, and chlorinated polyolefin resins;
3. The ink composition according to claim 1, wherein the content of said adhesion assisting resin is 1 to 50 parts by mass with respect to 100 parts by mass of said binder resin. The ink composition according to any one of claims 1 to 3, wherein the binder resin is a polyurethane resin and a cellulose resin. The ink composition according to any one of claims 1 to 4, further comprising resin beads having an average particle size of 2 µm or less. The ink composition according to any one of claims 1 to 5, further comprising a chelating agent. The ink composition according to any one of claims 1 to 6, further comprising a plasticizer. The ink composition according to any one of Claims 1 to 7, which does not substantially contain toluene. A laminate comprising a plastic substrate and a printed layer formed of the ink composition according to any one of Claims 1 to 8 and disposed on the surface of the plastic substrate. A food packaging material formed from the laminate according to claim 9 .