Liquid printing inks and printed materials

Abstract

To provide a liquid print ink that is particularly suitable for an assembly packaging film, exhibits improved adhesion and blocking resistance with respect to a heat-shrinkable film used for the assembly packaging film, the liquid print ink employing biomass material for improvements.SOLUTION: A liquid print ink uses a chlorinated polyolefin resin as a main binder resin and contains an organic solvent. Phospholipids are contained by 5-20 mass% relative to the total solid content of ink.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a liquid printing ink that can be used as a gravure ink or flexographic ink for flexible packaging. [Background technology]

[0002] The method of accumulating products such as canned beverages, plastic bottled beverages, and paper carton beverages using heat-shrinkable film (accumulating packaging film), which is inexpensive and easy to dispose of, instead of conventional cardboard, has been widely adopted, and is now used to accumulating not only beverages but also a variety of individually packaged items. Such accumulating packaging film is printed with liquid printing inks such as gravure ink and flexographic ink in order to impart visibility, beauty, and functionality to the items.

[0003] Printing on cumulative packaging films is usually done on the inside of the film to prevent loss of visibility during distribution. However, to preserve the advantages of low cost and easy disposal, the printed surface is usually not protected, and the printed surface is packaged in direct contact with the articles being packaged. Furthermore, cumulative packaging films are heat-shrinkable films, which shrink when heated to allow articles to be packaged. Therefore, sometimes the printing ink printed on the cumulative packaging film transfers to the articles during heating, film shrinkage, or distribution.

[0004] Furthermore, in recent years, there has been a demand for biomass packaging materials, and the printing inks used on packaging materials are also being required to use biomass materials rather than 100% petroleum-derived materials. There is a growing movement to use biomass materials to improve poor adhesion to film, which causes color transfer, insufficient blocking properties, and even printability itself.

[0005] Heat-shrinkable films used in integrated packaging films are made of polyolefin resins such as polyethylene resins and polypropylene resins, ester resins, polystyrene resins, etc. Liquid printing inks using chlorinated polyolefin resins are known as inks that have particularly excellent adhesion to polyolefin resin films (see, for example, Patent Documents 1 and 2). However, even with these inks, sufficient adhesion sometimes cannot be obtained. Furthermore, these inks do not take into account the possibility of using biomass raw materials for improvement. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] See JP 2009-073936 A [Patent Document 2] See JP 2019-38897 Summary of the Invention [Problem to be solved by the invention]

[0007] The problem to be solved by the present invention is to provide a liquid printing ink that is particularly suitable for integrated packaging films, that has excellent adhesion to heat-shrinkable films used in integrated packaging films, and that has improved blocking resistance, and that is improved using biomass raw materials. [Means for solving the problem]

[0008] As a result of intensive research by the present inventors to solve the above-mentioned problems, the present invention has been completed based on the discovery that the above-mentioned problems can be solved by a liquid printing ink containing a chlorinated polyolefin resin as a main binder resin and an organic solvent, and containing a specific amount of phospholipid relative to the total solid content of the ink.

[0009] That is, the present invention relates to a liquid printing ink containing a chlorinated polyolefin resin as a main binder resin and an organic solvent, characterized in that it contains 5 to 20 mass % of a phospholipid based on the total solid content of the ink.

[0010] The present invention also relates to a liquid printing ink in which the phospholipid is lecithin.

[0011] The present invention also relates to a printed matter obtained by printing with the liquid printing ink.

[0012] The present invention also relates to an integrated packaging film printed with the liquid printing ink. [Effects of the Invention]

[0013] The liquid printing ink of the present invention has excellent adhesion and blocking resistance, particularly to heat-shrinkable films such as polyolefin resin films. Stacked packaging films printed with the liquid printing ink of the present invention can be distributed without color transfer to stacked articles.

[0014] Furthermore, phospholipids are natural raw materials, and can contribute to the movement to improve them using biomass raw materials. DETAILED DESCRIPTION OF THE INVENTION

[0015] (Definition of words) In the present invention, the liquid printing ink refers to a liquid ink, such as gravure ink or flexographic ink, that is applied to a printing method using a printing plate, and is preferably gravure ink or flexographic ink. The liquid printing ink of the present invention does not contain any active energy curable component, i.e., is an active energy ray non-reactive liquid ink. In the present invention, all "parts" refer to "parts by mass," "total amount of coating agent" refers to the total amount of ink including all volatile components such as organic solvents, and "total amount of solids in coating agent" refers to the total amount of only non-volatile components, excluding volatile components.

[0016] (binder resin) The binder resin used in the present invention is a chlorinated vinyl resin, and in particular, a chlorinated polyolefin resin is used as the main binder resin.

[0017] (vinyl resin) In the chlorinated vinyl resin, the vinyl resin may be a homopolymer or copolymer of a compound having a vinyl group, and typical homopolymers or copolymers include homopolymers or copolymers using vinyl chloride or vinyl acetate. Examples of vinyl chloride resins include polyvinyl chloride, chlorinated polyvinyl chloride, polyvinylidene chloride, chlorinated polyethylene, vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl isobutyl ether copolymer, vinyl chloride-ethylene copolymer, vinyl chloride-propylene copolymer, vinyl chloride-styrene copolymer, vinyl chloride-isobutylene copolymer, vinyl chloride-vinylidene chloride copolymer, vinyl chloride-styrene-maleic anhydride terpolymer, vinyl chloride-styrene-acrylonitrile copolymer, vinyl chloride-butadiene copolymer, vinyl chloride-isoprene copolymer, and vinyl chloride-chlorinated propylene copolymer. Examples of vinyl chloride resins include vinyl chloride-vinylidene chloride-vinyl acetate terpolymers, vinyl chloride-maleic acid ester copolymers, vinyl chloride-methacrylic acid ester copolymers, vinyl chloride-acrylonitrile copolymers, and vinyl chloride-various vinyl ether copolymers, as well as blends thereof and other chlorine-free synthetic resins such as acrylonitrile-styrene copolymers, acrylonitrile-butadiene-styrene copolymers, ethylene-vinyl acetate copolymers, ethylene-ethyl (meth)acrylate copolymers, blends with polyesters, block copolymers, graft copolymers, etc. These vinyl chloride resins may be a mixture of two or more types, or may be a mixture with other synthetic resins.

[0018] Vinyl acetate resins are vinyl acetate polymers, which are homopolymers of vinyl acetate monomers, or copolymers of vinyl acetate monomers with polymerizable unsaturated monomers. Examples of unsaturated monomers include long-chain (meth)acrylic monomers, such as alkyl (meth)acrylate monomers (e.g., n-butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, lauryl (meth)acrylate, tridecyl (meth)acrylate, and stearyl (meth)acrylate; hydroxyl group-containing (meth)acrylic monomers, such as 2-hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, 1,4-butanediol mono(meth)acrylate, and (poly)ethylene glycol mono(meth)acrylate; carboxyl group-containing monomers, such as (meth)acrylic acid, maleic acid, and maleic anhydride; vinyl monomers, such as styrene, acrylonitrile, and vinyl chloride; and ethylene. These may be used alone or in combination of two or more. Among these, vinyl acetate polymers and vinyl acetate-ethylene copolymers are preferred.

[0019] The weight average molecular weight of the vinyl resin is preferably 5,000 to 100,000, more preferably 10,000 to 70,000.

[0020] The amount of the vinyl resin added is 1.0 to 70.0% by mass, preferably 5.0 to 50.0% by mass, based on the ink solid content.

[0021] (chlorinated vinyl resin) The chlorinated vinyl resin used in the present invention is a vinyl resin obtained by chlorinating the above-mentioned vinyl resin (also referred to as a chlorinated vinyl resin). Chlorination of vinyl resins can be carried out by known methods, such as a method in which a vinyl resin is dispersed or dissolved in a medium such as water, carbon tetrachloride, or chloroform, and chlorine gas is blown into the dispersion at a temperature of 50 to 120°C under pressurized or normal pressure in the presence of a catalyst or under ultraviolet irradiation. Examples of chlorinated vinyl resins include chlorinated polyolefin resins obtained by chlorinating polyolefin resins, such as chlorinated polypropylene resins obtained by chlorinating polypropylene resins, chlorinated propylene-α-olefin copolymers obtained by chlorinating propylene-α-olefin copolymers, chlorinated ethylene vinyl alcohol (EVA) resins obtained by chlorinating ethylene vinyl alcohol (EVA), and chlorinated ethylene-vinyl acetate copolymers obtained by chlorinating ethylene-vinyl acetate copolymers. Among these, chlorinated polyolefin resins and chlorinated ethylene-vinyl acetate copolymers are preferred. In the case of a chlorinated polyolefin resin, the weight average molecular weight is preferably 5,000 to 100,000, more preferably 5,000 to 70,000, and even more preferably 7,000 to 50,000. The chlorine content, which indicates the mass percentage of chlorine atoms contained in 100 mass% of the resin, is often within the range of 15 to 45 mass%. The chlorinated vinyl resin is contained in the ink solid content in an amount of 1.0 to 70 mass %, preferably 5 to 50 mass %.

[0022] Commercially available chlorinated vinyl resins may be used, and known examples include chlorinated polyolefin resins, chlorinated ethylene vinyl alcohol (EVA), and chlorinated ethylene-vinyl acetate copolymers, such as the Superchlor series from Nippon Paper Industries Co., Ltd.

[0023] In particular, in the present invention, it is preferable to use a chlorinated polyolefin resin as a main binder in combination with a vinyl resin or other chlorinated vinyl resin. The ratio of the combined use is not particularly limited, but preferably the ratio of chlorinated polyolefin resin to vinyl resin or other chlorinated vinyl resin is in the range of 5:1 to 1:5, more preferably 3:1 to 1:3, and most preferably 2:1 to 1:2. Here, the vinyl resin or other chlorinated vinyl resin is particularly preferably a vinyl resin that is a vinyl acetate-ethylene copolymer or a vinyl chloride-vinyl isobutyl ether copolymer, and the other chlorinated vinyl resin is preferably a chlorinated ethylene-vinyl acetate copolymer. When used in combination, the sum of the chlorinated polyolefin resin and the vinyl resin or other chlorinated vinyl resin is preferably contained in the ink solids at 2.0 to 70.0 mass %, more preferably 10.0 to 50.0 mass %.

[0024] In the present invention, there are no particular limitations on the binder resin other than the use of the chlorinated polyolefin resin or vinyl resin as the main binder resin, and known binder resins can also be used in combination, such as rosin resins, nitrocellulose, cellulose resins such as cellulose acetate propionate (CAP) and cellulose acetate butyronate (CAB), polyurethane resins, polyamide resins, acrylic resins, polyester resins, alkyd resins, ketone resins, cyclized rubber, chlorinated rubber, butyral, and petroleum resins.

[0025] (rosin-based resin) The rosin-based resin used in the present invention can be any rosin and / or rosin derivative commonly used in printing inks, without any particular limitation. Specifically, rosin or rosin derivatives include rosins or carboxyl group-containing derivatives thereof. Examples of rosins include gum rosin, wood rosin, tall oil rosin, disproportionated rosin, hydrogenated rosin, and polymers thereof. Examples of rosin derivatives include carboxyl group-containing derivatives such as rosin derivatives to which unsaturated carboxylic acids such as maleic acid, itaconic acid, and crotonic acid have been added. The amount of rosin resin added is preferably 0.1 to 20.0% by mass, more preferably 0.2 to 15.0% by mass, based on the ink solid content.

[0026] In the present invention, it is particularly preferable to use a rosin-modified maleic acid resin, which is a maleic acid derivative of rosin. The rosin-modified maleic acid resin used in the present invention is not particularly limited, and any known rosin-modified maleic acid resin can be used. The rosin-modified maleic acid resin preferably has an acid value of 25 mg KOH / g or more and 320 mg KOH / g or less, and particularly preferably has an acid value of 100 mg KOH / g or more and 320 mg KOH / g or less. The amount of the rosin-modified maleic acid resin added is preferably 0.1 to 20.0 mass % relative to the ink solid content, and more preferably 0.2 to 15.0 mass %.

[0027] Examples of commercially available rosin-based resins include Marquid Nos. 1, 2, 5, 6, 8, 31, 32, 33, 34, and 3002 manufactured by Arakawa Chemical Industries, Ltd., and Harimac R-80, T-80, R-100, M-453, M-130A, 135GN, 145P, and R-120AH, and Haritac 4851, 4821, 4740, and 28JA manufactured by Harima Chemicals Co., Ltd. These rosin-based resins can also be used as biomass raw materials.

[0028] (cellulose resin) Examples of cellulose-based resins include cellulose acetate propionate, cellulose acetate butyrate, and other cellulose ester resins, nitrocellulose (also known as soluble cellulose), hydroxyalkyl cellulose, and carboxyalkyl cellulose. The cellulose ester resin preferably has an alkyl group, and examples of the alkyl group include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a pentyl group, and a hexyl group, and the alkyl group may further have a substituent. Of the above, cellulose acetate propionate, cellulose acetate butyrate, and nitrocellulose are preferred as cellulose-based resins. Nitrocellulose is particularly preferred. The weight-average molecular weight of the cellulose-based resin is preferably 5,000 to 200,000, more preferably 10,000 to 50,000. The glass transition temperature of the cellulose-based resin is preferably 120°C to 180°C. When used in combination with the polyurethane resin (A) of the present invention, improvements in blocking resistance, scratch resistance, and other physical properties of the ink film can be expected. Nitrocellulose (nitrocellulose) is preferably obtained as a nitric acid ester by reacting natural cellulose with nitric acid to replace three hydroxyl groups in the six-membered ring of the anhydroglucopyranose group in the natural cellulose with nitric acid groups.

[0029] The use of nitrocellulose (nitrocellulose) provides high dispersibility in pigments, and is therefore suitable for use as a coating agent for surface printing, as it can improve the strength of the printing ink film. The nitrocellulose (nitrocellulose) preferably has a nitrogen content of 10 to 13% by mass and an average degree of polymerization of 30 to 500, and more preferably has a nitrogen content of 10 to 13% by mass and an average degree of polymerization of 45 to 290.

[0030] The amount of nitrocellulose (nitrocellulose) added is 0.1 to 5.0% by mass, preferably 0.5 to 2.0% by mass, based on the ink solid content. Nitrocellulose can also be used as a biomass feedstock.

[0031] (Polyurethane resin) The polyurethane resin is not particularly limited as long as it is a polyurethane resin obtained by reacting a polyol with a polyisocyanate. Examples of polyols that can be used include various known polyols that are commonly used in the production of polyurethane resins, and one or more of these may be used in combination. Examples of suitable polyols include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 2-methyl-1,3-propanediol, 2-ethyl-2-butyl-1,3-propanediol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol, pentanediol, 3-methyl-1,5-pentanediol, hexanediol, octanediol, 1,4-butynediol, 1,4-butylenediol, diethylene glycol, triethylene glycol, and dipropylene glycol. Saturated or unsaturated low molecular weight polyols (1) such as ethylene glycol, glycerin, trimethylolpropane, trimethylolethane, 1,2,6-hexanetriol, 1,2,4-butanetriol, sorbitol, and pentaerythritol; these low molecular weight polyols (1) and sebacic acid, adipic acid, phthalic acid, isophthalic acid, terephthalic acid, maleic acid, fumaric acid, succinic acid, oxalic acid, malonic acid, glutaric acid, pimelic acid, suberic acid, azelaic acid, and trimellitic acid. polyester polyols (2) obtained by dehydration condensation or polymerization of polycarboxylic acids such as methyl acrylate, pyromellitic acid, or their anhydrides; polyester polyols (3) obtained by ring-opening polymerization of cyclic ester compounds, for example, lactones such as polycaprolactone, polyvalerolactone, and poly(β-methyl-γ-valerolactone); polycarbonate polyols (4) obtained by reacting the low-molecular-weight polyols (1) or the like with, for example, dimethyl carbonate, diphenyl carbonate, ethylene carbonate, phosgene, or the like; polybutadiene glycols (5); glycols (6) obtained by adding ethylene oxide or propylene oxide to bisphenol A; and acrylic polyols (7) obtained by copolymerizing, in one molecule, one or more hydroxyethyl groups, hydroxypropyl acrylate, hydroxybutyl acrylate, or the like, or the corresponding methacrylic acid derivatives, with, for example, acrylic acid, methacrylic acid, or an ester thereof.

[0032] Examples of polyisocyanates include various known aromatic diisocyanates, aliphatic diisocyanates, and alicyclic diisocyanates that are generally used in the production of polyurethane resins. For example, 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate, 1-methyl-2,4-phenylene diisocyanate, 1-methyl-2,6-phenylene diisocyanate, 1-methyl-2,5-phenylene diisocyanate, 1-methyl-2,6-phenylene diisocyanate, 1-methyl-3,5-phenylene diisocyanate, 1-ethyl-2,4-phenylene diisocyanate, 1-isopropyl-2,4-phenylene diisocyanate, 1,3-dimethyl-2,4-phenylene diisocyanate, 1,3-dimethyl-4,6-phenylene diisocyanate, 1,4-dimethyl-2,5-phenylene diisocyanate, diethylbenzene diisocyanate, diisopropylbenzene diisocyanate, 1-methyl-3,5-diethylbenzene Aromatic polyisocyanates such as zenediisocyanate, 3-methyl-1,5-diethylbenzene-2,4-diisocyanate, 1,3,5-triethylbenzene-2,4-diisocyanate, naphthalene-1,4-diisocyanate, naphthalene-1,5-diisocyanate, 1-methyl-naphthalene-1,5-diisocyanate, naphthalene-2,6-diisocyanate, naphthalene-2,7-diisocyanate, 1,1-dinaphthyl-2,2'-diisocyanate, biphenyl-2,4'-diisocyanate, biphenyl-4,4'-diisocyanate, 3-3'-dimethylbiphenyl-4,4'-diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,2'-diphenylmethane diisocyanate, and diphenylmethane-2,4-diisocyanate;Aliphatic or alicyclic polyisocyanates such as tetramethylene diisocyanate, hexamethylene diisocyanate, dodecamethylene diisocyanate, trimethylhexamethylene diisocyanate, 1,3-cyclopentylene diisocyanate, 1,3-cyclohexylene diisocyanate, 1,4-cyclohexylene diisocyanate, 1,3-di(isocyanatomethyl)cyclohexane, 1,4-di(isocyanatomethyl)cyclohexane, lysine diisocyanate, isophorone diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, 2,4'-dicyclohexylmethane diisocyanate, 2,2'-dicyclohexylmethane diisocyanate, and 3,3'-dimethyl-4,4'-dicyclohexylmethane diisocyanate can be used. These polyisocyanates can be used alone or in combination of two or more. Among these, these diisocyanate compounds can be used alone or in combination of two or more.

[0033] Chain extenders can also be used. Examples of chain extenders include ethylenediamine, propylenediamine, hexamethylenediamine, diethylenetriamine, triethylenetetramine, isophoronediamine, and dicyclohexylmethane-4,4'-diamine, as well as amines having a hydroxyl group in the molecule, such as 2-hydroxyethylethylenediamine, 2-hydroxyethylpropyldiamine, 2-hydroxyethylpropylenediamine, di-2-hydroxyethylethylenediamine, di-2-hydroxyethylenediamine, di-2-hydroxyethylpropylenediamine, 2-hydroxypropylethylenediamine, di-2-hydroxypropylethylenediamine, and di-2-hydroxypropylethylenediamine. These chain extenders can be used alone or in combination of two or more.

[0034] Monovalent active hydrogen compounds can also be used as end-capping agents for the purpose of terminating the reaction. Examples of such compounds include dialkylamines such as di-n-butylamine and alcohols such as ethanol and isopropyl alcohol. Furthermore, when it is particularly desired to introduce carboxyl groups into the polyurethane resin, amino acids such as glycine and L-alanine can be used as reaction terminators. These end-capping agents can be used alone or in combination. The weight average molecular weight of the polyurethane resin is preferably 10,000 to 100,000, and more preferably in the range of 15,000 to 80,000. The amount of polyurethane resin added is preferably 0.1 to 5.0% by mass, more preferably 0.5 to 2.0% by mass, based on the ink solid content.

[0035] (Polyamide resin) The polyamide resin is, for example, a thermoplastic polyamide soluble in an organic solvent, obtainable by polycondensation of a polybasic acid and a polyamine. In particular, a polyamide resin containing a reaction product of an acid component containing a polymerized fatty acid and / or a dimer acid with an aliphatic and / or aromatic polyamine is preferred, and one containing a portion of primary and secondary monoamines is even more preferred. Polybasic acids used as raw materials for polyamide resins include, but are not limited to, adipic acid, sebacic acid, azelaic acid, phthalic anhydride, isophthalic acid, suberic acid, glutaric acid, fumaric acid, pimelic acid, oxalic acid, malonic acid, succinic acid, maleic acid, terephthalic acid, 1,4-cyclohexyldicarboxylic acid, trimellitic acid, dimer acid, hydrogenated dimer acid, and polymerized fatty acid. Among these, polyamide resins containing a structure derived from dimer acid or polymerized fatty acid as the main component (50% by weight or more in the polyamide resin) are preferred. Here, polymerized fatty acid is obtained by, for example, the cyclization reaction of unsaturated fatty acid, and includes monobasic fatty acid, dimerized polymerized fatty acid (dimer acid), trimerized polymerized fatty acid, and the like. Fatty acids constituting dimer acid or polymerized fatty acid include those derived from natural oils such as soybean oil, palm oil, and rice bran oil, with those derived from oleic acid and linoleic acid being preferred. The polybasic acid may be used in combination with a monocarboxylic acid, such as acetic acid, propionic acid, lauric acid, palmitic acid, benzoic acid, or cyclohexanecarboxylic acid.

[0036] Examples of polyamines include polyamines and primary or secondary monoamines. Examples of polyamines used in polyamide resins include aliphatic diamines such as ethylenediamine, propylenediamine, hexamethylenediamine, and methylaminopropylamine, and aliphatic polyamines such as diethylenetriamine and triethylenetetramine. Examples of alicyclic polyamines include cyclohexylenediamine and isophoronediamine. Examples of aromatic aliphatic polyamines include xylylenediamine, and examples of aromatic polyamines include phenylenediamine and diaminodiphenylmethane. Examples of primary and secondary monoamines include n-butylamine, octylamine, diethylamine, monoethanolamine, monopropanolamine, diethanolamine, and dipropanolamine. The amount of polyamide resin added is 0.1 to 5.0% by mass, preferably 0.5 to 2.0% by mass, based on the ink solid content.

[0037] (acrylic resin) The acrylic resin is not particularly limited as long as it is a copolymer of polymerizable monomers whose main component is a (meth)acrylic acid ester. Examples of polymerizable monomers include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, iso-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, iso-octyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, iso-nonyl (meth)acrylate, cyclohexyl (meth)acrylate, benzyl (meth)acrylate, methoxyethyl (meth)acrylate, ethoxyethyl (meth)acrylate, and phenoxyethyl (meth)acrylate. The polymerization method is also not particularly limited, and those obtained by known methods such as bulk polymerization, solution polymerization, emulsion polymerization, and suspension polymerization can be used. The weight average molecular weight of the acrylic resin is preferably 5,000 to 200,000, and more preferably in the range of 10,000 to 100,000. The amount of acrylic resin added is 0.1 to 5.0% by mass, preferably 0.5 to 2.0% by mass, based on the ink solid content.

[0038] (polyester resin) The polyester resin is not particularly limited as long as it is a polyester resin obtained by reacting an alcohol with a carboxylic acid using a known esterification polymerization reaction. Examples of alcohols include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 2-methyl-1,3-propanediol, 2-ethyl-2-butyl-1,3propanediol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol, 1,5-pentanediol, 1,2-pentanediol, 3-methyl-1,5-pentanediol, hexanediol, octanediol, 1,4-butynediol, 1,4-butylenediol, diethylene glycol, triethylene glycol, dipropylene glycol, glycerin, trimethylolpropane, trimethylolethane, 1,2,6-hexanetriol, 1,2,4-butanetriol, sorbitol, pentaerythritol, 1,4-cyclohexanediol, 1,2-cyclohexanediol, 1,4-cyclohexanedimethanol, 1,2-cyclohexanedimethanol, spiroglycol, and isosorbide. These may be used alone or in combination of two or more. Among these, polyfunctional alcohols are preferred. Examples of carboxylic acids include formic acid, acetic acid, propionic acid, butanoic acid, pentanoic acid, hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, decanoic acid, oleic acid, linoleic acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, phthalic acid, and 1,4-cyclohexanedicarboxylic acid. These may be used alone or in combination of two or more. Among these, polyfunctional carboxylic acids are preferred. The weight average molecular weight of the polyester resin is preferably 500 to 6000, more preferably 1400 to 5500. The amount of polyester resin added is 0.1 to 5.0% by mass, preferably 0.5 to 2.0% by mass, based on the ink solid content.

[0039] (hardening agent) A curing agent may be used in combination with the binder resin. The curing agent may be any of those commonly used in organic solvent-based gravure inks, but the most commonly used are isocyanate-based curing agents. The amount of the isocyanate compound added is 0.3 to 10.0% by mass, preferably 1.0 to 7.0% by mass, based on the ink solids, from the viewpoint of curing efficiency.

[0040] The total content of the binder resins is 2.0 to 50% by mass, preferably 10 to 50% by mass, based on the ink solid content.

[0041] (phospholipids) The present invention is characterized in that the ink contains 5 to 20% by mass of phospholipids relative to the total solid content of the ink. Examples of phospholipids include lecithin, phosphorylated mono- and diglycerides, polydimethylsiloxane, and triglycerides, with lecithin being preferred as it is readily available.

[0042] The addition of phospholipids improves adhesion to plastic films and blocking resistance, especially for biaxially oriented polypropylene films that have not undergone surface treatment such as corona treatment. Although this is only a guess, it is thought that phospholipids have a release effect, which improves the balance of the release action at the interface between the ink and the plastic film, resulting in improved adhesion to the film and blocking resistance. Phospholipids can also be used as a biomass feedstock.

[0043] Phospholipids are effective when contained in an amount of 5 to 20% by mass of the total solid content of the ink. If the amount exceeds 20% by mass, printability may be reduced. In particular, the amount added is 5 to 19% by mass, preferably 7 to 15% by mass, of the ink solid content.

[0044] (organic solvent) The organic solvent used in the liquid printing ink of the present invention is not particularly limited, and examples thereof include aromatic hydrocarbon organic solvents such as toluene, xylene, Solvesso #100, Solvesso #150, etc.; aliphatic hydrocarbon organic solvents such as hexane, methylcyclohexane, heptane, octane, decane, etc.; and various ester organic solvents such as methyl acetate, ethyl acetate, isopropyl acetate, normal propyl acetate, butyl acetate, amyl acetate, ethyl formate, butyl propionate, etc. Examples of water-miscible organic solvents include alcohols such as methanol, ethanol, propanol, butanol, and isopropyl alcohol, ketones such as acetone, methyl ethyl ketone, and cyclohexanone, and glycol ethers such as ethylene glycol (mono- and di-)methyl ether, ethylene glycol (mono- and di-)ethyl ether, ethylene glycol monopropyl ether, ethylene glycol monoisopropyl ether, monobutyl ether, diethylene glycol (mono- and di-)methyl ether, diethylene glycol (mono- and di-)ethyl ether, diethylene glycol monoisopropyl ether, diethylene glycol monobutyl ether, triethylene glycol (mono- and di-)methyl ether, propylene glycol (mono- and di-)methyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, and dipropylene glycol (mono- and di-)methyl ether. These can be used alone or in combination of two or more.

[0045] From the viewpoints of both work hygiene during printing and the harmfulness of packaging materials, it is more preferable to use ethyl acetate, propyl acetate, isopropanol, normal propanol, etc., and not to use aromatic solvents such as toluene or ketone solvents such as methyl ethyl ketone.

[0046] Among these, a mixture of isopropyl alcohol, ethyl acetate, and methoxypropanol is more preferable from the viewpoint of solubility in polyurethane resin. Also, glycol ethers can be added as long as they are less than 10% by mass of the ink solids to adjust the drying properties.

[0047] (coloring agent) The liquid printing ink of the present invention can be used as a varnish for adjusting the density of ink that does not contain a colorant or as an overprint varnish, or as an ink containing a colorant that is used in design printing, etc., for the purpose of imparting cosmetic properties, etc., including a colorant. The colorant is preferably a pigment, and examples thereof include inorganic pigments and organic pigments used in general inks, paints, recording agents, etc. Examples of organic pigments include soluble azo pigments, insoluble azo pigments, azo pigments, phthalocyanine pigments, halogenated phthalocyanine pigments, anthraquinone pigments, anthanthrone pigments, dianthraquinonyl pigments, anthrapyrimidine pigments, perylene pigments, perinone pigments, quinacridone pigments, thioindigo pigments, dioxazine pigments, isoindolinone pigments, quinophthalone pigments, azomethine azo pigments, flavanthrone pigments, diketopyrrolopyrrole pigments, isoindoline pigments, indanthrone pigments, and carbon black pigments. Other examples include carmine 6B, lake red C, permanent red 2B, disazo yellow, pyrazolone orange, carmine FB, cromophtal yellow, cromophtal red, phthalocyanine blue, phthalocyanine green, dioxazine violet, quinacridone magenta, quinacridone red, indanthrone blue, pyrimidine yellow, thioindigo bordeaux, thioindigo magenta, perylene red, perinone orange, isoindolinone yellow, aniline black, diketopyrrolopyrrole red, and daylight fluorescent pigments. Both non-acid-treated and acid-treated pigments can be used. Specific examples of preferred organic pigments are listed below.

[0048] Examples of black pigments include CI Pigment Black 1, CI Pigment Black 6, CI Pigment Black 7, CI Pigment Black 9, and CI Pigment Black 20.

[0049] Examples of indigo pigments include CI Pigment Blue 15, CI Pigment Blue 15:1, CI Pigment Blue 15:2, CI Pigment Blue 15:3, CI Pigment Blue 15:4, CI Pigment Blue 15:5, CI Pigment Blue 15:6, CI Pigment Blue 16, CI Pigment Blue 17:1, CI Pigment Blue 22, CI Pigment Blue 24:1, CI Pigment Blue 25, CI Pigment Blue 26, CI Pigment Blue 60, CI Pigment Blue 61, CI Pigment Blue 62, CI Pigment Blue 63, CI Pigment Blue 64, CI Pigment Blue 75, CI Pigment Blue 79, and CI Pigment Blue 80.

[0050] Examples of green pigments include CI Pigment Green 1, CI Pigment Green 4, CI Pigment Green 7, CI Pigment Green 8, CI Pigment Green 10, and CI Pigment Green 36.

[0051] Examples of red pigments include CI Pigment Red 1, CI Pigment Red 2, CI Pigment Red 3, CI Pigment Red 4, CI Pigment Red 5, CI Pigment Red 6, CI Pigment Red 7, CI Pigment Red 8, CI Pigment Red 9, CI Pigment Red 10, CI Pigment Red 11, CI Pigment Red 12, CI Pigment Red 15, CI Pigment Red 16, CI Pigment Red 17, CI Pigment Red 18, CI Pigment Red 19, CI Pigment Red 20, CI Pigment Red 21, CI Pigment Red 22, CI Pigment Red 23, CI Pigment Red 24, CI Pigment Red 25, CI Pigment Red 26, CI Pigment Red 27, CI Pigment Red 28, CI Pigment Red 29, CI Pigment Red 30, CI Pigment Red 31, CI Pigment Red 32, CI Pigment Red 33, CI Pigment Red 34, CI Pigment Red 35, CI Pigment Red 36, CI Pigment Red 37, CI Pigment Red 38, CI Pigment Red 39, CI Pigment Red 40, CI Pigment Red 41, CI Pigment Red 42, CI Pigment Red 43, CI Pigment Red 44, CI Pigment Red 45, CI Pigment Red 46, CI Pigment Red 47, CI Pigment Red 48, CI Pigment Red 49, CI Pigment Red 50, CI Pigment Red 51, CI Pigment Red 52, CI Pigment Red 53, CI Pig Red 19, CI Pigment Red 20, CI Pigment Red 21, CI Pigment Red 22, CI Pigment Red 23, CI Pigment Red 31, CI Pigment Red 32, CI Pigment Red 38, CI Pigment Red 41, CI Pigment Red 43, CI Pigment Red 46, CI Pigment Red 48, CI Pigment Red 48:1, CI Pigment Red 48:2, CI Pigment Red 48:3, CI Pigment Red 48:4, CI Pigment Red 48:5, CI Pigment Red 48:6, CI Pigment Red 49, CI Pigment Red 49:1, CI Pigment Red 49:2, CI Pigment Red 49:3, CI Pigment Red 52, CI Pigment Red 52:1, CI Pigment Red 52:2, CI Pigment Red 53, CI Pigment Red 53:1, CI Pigment Red 53:2, CI Pigment Red 53:3, CI Pigment Red 54, CI Pigment Red 57, CI Pigment Red 57: 1, CI Pigment Red 58, CI Pigment Red 58:1, CI Pigment Red 58:2, CI Pigment Red 58:3, CI Pigment Red 58:4, CI Pigment Red 60:1, CI Pigment Red 63, CI Pigment Red 63:1, CI Pigment Red 63:2, CI Pigment Red 63:3, CI Pigment Red 64:1, CI Pigment Red 68, CI Pigment Red 68, CI Pigment Red 81:1, CI Pigment Red 83, C.I. Pigment Red 88, CI Pigment Red 89, CI Pigment Red 95, CI Pigment Red 112, CI Pigment Red 114, CI Pigment Red 119, CI Pigment Red 122, CI Pigment Red 123, CI Pigment Red 136, CI Pigment Red 144, CI Pigment Red 146, CI Pigment Red 147, CI Pigment Red 149, CI Pigment Red 150, CI Pigment Red 164, CI Pigment Red Red 166, CI Pigment Red 168, CI Pigment Red 169, CI Pigment Red 170, CI Pigment Red 171, CI Pigment Red 172, CI Pigment Red 175, CI Pigment Red 176, CI Pigment Red 177, CI Pigment Red 178, CI Pigment Red 179, CI Pigment Red 180, CI Pigment Red 181, CI Pigment Red 182, CI Pigment Red 183, CI Pigment Red 184, CI Pigment Red 185, CI Pigment Red 187, CI Pigment Red 188, CI Pigment Red 190, CI Pigment Red 192, CI Pigment Red 193, CI Pigment Red 194, CI Pigment Red 200, CI Pigment Red 202, CI Pigment Red 206, CI Pigment Red 207, CI Pigment Red 208, CI Pigment Red 209, CI Pigment Red 210, CI Pigment Red 211, CI Pigment Red Red 213, CI Pigment Red 214, CI Pigment Red 216, CI Pigment Red 215, CI Pigment Red 216, CI Pigment Red 220, CI Pigment Red 221, CI Pigment Red 223, CI Pigment Red 224, CI Pigment Red 226, CI Pigment Red 237, CI Pigment Red 238, CI Pigment Red 239, CI Pigment Red 240, CI Pigment Red 242, CI Pigment Red 245, CIPigment Red 247, CI Pigment Red 248, CI Pigment Red 251, CI Pigment Red 253, CI Pigment Red 254, CI Pigment Red 255, CI Pigment Red 256, CI Pigment Red 257, CI Pigment Red 258, CI Pigment Red 260, CI Pigment Red 262, CI Pigment Red 263, CI Pigment Red 264, CI Pigment Red 266, CI Pigment Red 268, CI Pigment Red 269, CI Pigment Red 270, CI Pigment Red 271, CI Pigment Red 272, CI Pigment Red 279, etc.

[0052] Examples of purple pigments include CI Pigment Violet 1, CI Pigment Violet 2, CI Pigment Violet 3, CI Pigment Violet 3:1, CI Pigment Violet 3:3, CI Pigment Violet 5:1, CI Pigment Violet 13, CI Pigment Violet 19 (γ type, β type), CI Pigment Violet 23, CI Pigment Violet 25, CI Pigment Violet 27, CI Pigment Violet 29, CI Pigment Violet 31, CI Pigment Violet 32, CI Pigment Violet 36, CI Pigment Violet 37, CI Pigment Violet 38, CI Pigment Violet 42, and CI Pigment Violet 50.

[0053] Examples of yellow pigments include CI Pigment Yellow 1, CI Pigment Yellow 3, CI Pigment Yellow 12, CI Pigment Yellow 13, CI Pigment Yellow 14, Pigment Yellow 17, CI Pigment Yellow 24, CI Pigment Yellow 42, CI Pigment Yellow 55, CI Pigment Yellow 62, CI Pigment Yellow 65, CI Pigment Yellow 74, CI Pigment Yellow 83, CI Pigment Yellow 86, CI Pigment Yellow 93, CI Pigment Yellow 94, CI Pigment Yellow 95, CI Pigment Yellow 109, CI Pigment Yellow 110, CI Pigment Yellow 117, CI Pigment Yellow 119, CI Pigment Yellow 120, CI Pigment Yellow 121, CI Pigment Yellow 122, CI Pigment Yellow 123, CI Pigment Yellow 124, CI Pigment Yellow 125, CI Pigment Yellow 126, CI Pigment Yellow 127, CI Pigment Yellow 128, CI Pigment Yellow 129, CI Pigment Yellow 130, CI Pigment Yellow 131, CI Pigment Yellow 132, CI Pigment Yellow 133, CI Pigment Yellow 134, CI Pigment Yellow 135, CI Pigment Yellow 136, CI Pigment Yellow 137, CI Pigment Yellow 138, CI Pigment Yellow 139, CI Pigment Yellow 140, CI Pigment Yellow 141, CI Pigment Yellow 142, CI Pigment Yellow 143, CI Pigment Yellow 144, CI Pigment Yellow 145, CI Pigment Yellow 14 Yellow 120, Pigment Yellow 125, CI Pigment Yellow 128, CI Pigment Yellow 129, CI Pigment Yellow 137, CI Pigment Yellow 138, CI Pigment Yellow 139, CI Pigment Yellow 147, CI Pigment Yellow 148, CI Pigment Yellow 150, CI Pigment Yellow 151, CI Pigment Yellow 153, CI Pigment Yellow 154, CI Pigment Yellow 155, CI Pigment Yellow 166, CI Pigment Yellow 168, CI Pigment Yellow 174, CI Pigment Yellow 180, CI Pigment Yellow 185 and CI Pigment Yellow 213.

[0054] Examples of orange pigments include CI Pigment Orange 5, CI Pigment Orange 13, CI Pigment Orange 16, CI Pigment Orange 34, CI Pigment Orange 36, CI Pigment Orange 37, CI Pigment Orange 38, CI Pigment Orange 43, CI Pigment Orange 51, CI Pigment Orange 55, CI Pigment Orange 59, CI Pigment Orange 61, CI Pigment Orange 64, CI Pigment Orange 71, and CI Pigment Orange 74.

[0055] Examples of brown pigments include CI Pigment Brown 23, CI Pigment Brown 25, and CI Pigment Brown 26.

[0056] Among them, preferred pigments include CI Pigment Black 7 as a black pigment, Indigo pigments include CI Pigment Blue 15, CI Pigment Blue 15:1, CI Pigment Blue 15:2, CI Pigment Blue 15:3, CI Pigment Blue 15:4, CI Pigment Blue 15:6, CI Pigment Green 7 as a green pigment, Red pigments include CI Pigment Red 57:1, CI Pigment Red 48:1, CI Pigment Red 48:2, CI Pigment Red 48:3, CI Pigment Red 146, CI Pigment Red 242, CI Pigment Red 185, CI Pigment Red 122, CI Pigment Red 178, CI Pigment Red 149, CI Pigment Red 144, CI Pigment Red 166, Purple pigments include CI Pigment Violet 23 and CI Pigment Violet 37. Yellow pigments include CI Pigment Yellow 83, CI Pigment Yellow 14, CI Pigment Yellow 180, CI Pigment Yellow 139, Orange pigments include CI Pigment Orange 38, CI Pigment Orange 13, CI Pigment Orange 34, CI Pigment Orange 64, It is preferable to use at least one or two or more selected from this group.

[0057] Examples of inorganic pigments include white inorganic pigments such as titanium oxide, zinc oxide, zinc sulfide, barium sulfate, calcium carbonate, chromium oxide, silica, lithopone, antimony white, and gypsum. Among inorganic pigments, titanium oxide is particularly preferred. Titanium oxide exhibits a white color and is preferred in terms of coloring power, hiding power, chemical resistance, and weather resistance. From the viewpoint of printing performance, titanium oxide that has been treated with silica and / or alumina is preferred.

[0058] Examples of inorganic pigments other than white include aluminum particles, mica, bronze powder, chrome vermilion, yellow lead, cadmium yellow, cadmium red, ultramarine, Prussian blue, red iron oxide, yellow iron oxide, iron black, and zircon. Aluminum is in powder or paste form, but it is preferably used in paste form from the standpoints of handleability and safety, and whether leafing or non-leafing aluminum is used is selected appropriately from the standpoints of brightness and concentration.

[0059] The pigment is preferably contained in an amount sufficient to ensure the concentration and coloring strength of the liquid printing ink, i.e., 1 to 60% by mass of the total mass of the ink, or 10 to 90% by mass in terms of the weight ratio of solids in the ink. These pigments can be used alone or in combination of two or more.

[0060] The liquid printing ink of the present invention may further contain, if necessary, an extender pigment, a leveling agent, an antifoaming agent, a plasticizer, an infrared absorbing agent, an ultraviolet absorbing agent, an aromatic agent, a flame retardant, and the like. For example, if an appropriate amount of silica is added as the extender pigment, the abrasion resistance tends to be further improved.

[0061] The liquid printing ink of the present invention can be produced by dissolving and / or dispersing a binder resin, a pigment, etc. in an organic solvent. Specifically, the ink can be produced by dispersing a pigment in an organic solvent with a binder resin to produce a pigment dispersion, and then blending other compounds, etc., as necessary, with the resulting pigment dispersion.

[0062] The particle size distribution of the pigment in the pigment dispersion can be adjusted by appropriately adjusting the size of the grinding media of the disperser, the packing ratio of the grinding media, the dispersion treatment time, the discharge speed of the pigment dispersion, the viscosity of the pigment dispersion, etc. As the disperser, a commonly used one, for example, a roller mill, a ball mill, a pebble mill, an attritor, a sand mill, etc. can be used. If the ink contains air bubbles or unexpectedly large particles, these will degrade the quality of the printed matter, so it is preferable to remove them by filtration, etc. Any conventional filter can be used.

[0063] The viscosity of the ink produced by the above method is preferably in the range of 10 mPa·s or more to prevent pigment sedimentation and ensure adequate dispersion, and 1000 mPa·s or less to ensure efficient operation during ink production and printing. The above viscosity was measured at 25°C using a Tokimec B-type viscometer. The viscosity of the ink can be adjusted by appropriately selecting the types and amounts of raw materials used, binder resins, pigments, organic solvents, etc. The viscosity of the ink can also be adjusted by adjusting the particle size and particle size distribution of the pigments in the ink.

[0064] (Printed matter and laminates) A printed material can be obtained by printing the liquid printing ink of the present invention onto any substrate. The substrate used in the present invention is not particularly limited, and may be a paper or plastic substrate commonly used in gravure or flexographic printing, or a flexible packaging substrate used in food packaging. Examples of paper include fine paper used in printing packaging materials for cosmetics, beverages, pharmaceuticals, toys, and equipment, as well as kraft paper, pure white roll paper, glassine paper, parchment paper, Manila cardboard, white cardboard, coated paper, art paper, construction paper, tissue paper, cardboard, polyethylene-coated paper, and various synthetic papers.

[0065] Examples of film substrates include films and laminates made of polyamide resins such as nylon 6, nylon 66, and nylon 46; polyester resins such as polyethylene terephthalate (PET), polyethylene naphthalate, polytrimethylene terephthalate, polytrimethylene naphthalate, polybutylene terephthalate, and polybutylene naphthalate; biodegradable resins such as polyhydroxycarboxylic acids such as polylactic acid; aliphatic polyester resins such as poly(ethylene succinate) and poly(butylene succinate); thermoplastic resins such as polyolefin resins such as polypropylene and polyethylene, polyimide resins, polyarylate resins, and mixtures thereof. Among these, films made of polyethylene terephthalate (PET), polyester, polyamide, polyethylene, and polypropylene are particularly preferred. These substrate films may be unstretched or stretched, and their manufacturing method is not limited. The thickness of the substrate film is also not particularly limited, but is typically within the range of 1 to 500 μm. The printing surface of the substrate film is preferably subjected to a corona discharge treatment, and may be vapor-deposited with aluminum, silica, alumina, or the like.

[0066] It is also preferable to use a film made of a material containing biomass-derived components as the film substrate. Biomass films are commercially available from various companies, and for example, sheets such as those listed in the list of biomass-certified products listed by the Japan Organics Recycling Association can be used.

[0067] Specifically, well-known films are made from biomass-derived ethylene glycol. Biomass-derived ethylene glycol is made from ethanol (biomass ethanol) produced from biomass as a raw material. For example, biomass-derived ethylene glycol can be obtained by converting biomass ethanol into ethylene oxide by a conventionally known method to produce ethylene glycol. Alternatively, commercially available biomass ethylene glycol may be used; for example, biomass ethylene glycol commercially available from India Glycoal Limited can be suitably used.

[0068] Alternatively, products made from biomass materials are also available, classified by their biomass plastic content as specified by ISO 16620 or ASTM D6866. Radioactive carbon-14C exists in the atmosphere at a rate of 1 in 1012 particles, and this rate remains the same for atmospheric carbon dioxide, so this rate remains the same even in plants that fix this carbon dioxide through photosynthesis. Therefore, the carbon in plant-derived resins contains radioactive carbon-14C. In contrast, the carbon in fossil fuel-derived resins contains almost no radioactive carbon-14C. Therefore, by measuring the concentration of radioactive carbon-14C in the resin using an accelerator mass spectrometer, the plant-derived resin content, or biomass plastic content, can be determined. Examples of plant-derived low-density polyethylene that is a biomass plastic having a biomass plastic content of 80% or more, preferably 90% or more as specified by ISO 16620 or ASTM D6866 include products manufactured by Braskem under the trade names "SBC818," "SPB608," "SBF0323HC," "STN7006," "SEB853," and "SPB681," and films using these as raw materials can be suitably used.

[0069] For example, as an alternative to conventional polyethylene terephthalate films made from petroleum-based raw materials, films containing biomass polyesters and biomass polyethylene terephthalates, which have biomass-derived ethylene glycol as the diol unit and fossil fuel-derived dicarboxylic acids as the dicarboxylic acid units, are known. The dicarboxylic acid units of the biomass polyester are derived from fossil fuels, and aromatic dicarboxylic acids, aliphatic dicarboxylic acids, and derivatives thereof can be used without limitation. Furthermore, the copolymer polyester may be one in which, in addition to the above diol component and dicarboxylic acid component, a copolymerization component is added as a third component, such as a bifunctional oxycarboxylic acid, or at least one polyfunctional compound selected from the group consisting of a trifunctional or higher functional polyhydric alcohol, a trifunctional or higher functional polycarboxylic acid and / or anhydride thereof, and a trifunctional or higher functional oxycarboxylic acid, in order to form a crosslinked structure.

[0070] Furthermore, for example, as an alternative to conventional polyolefin films using petroleum-based raw materials, biomass polyolefin films such as biomass polyethylene films and biomass polyethylene-polypropylene films containing polyethylene resins made from biomass-derived ethylene glycol are also known. The polyethylene resin is not particularly limited except that ethylene glycol derived from biomass is used as part of the raw material, and examples thereof include ethylene homopolymers and copolymers of ethylene and α-olefins with ethylene as the main component (ethylene-α-olefin copolymers containing 90% by mass or more of ethylene units), and these can be used alone or in combination of two or more. The α-olefin constituting the copolymer of ethylene and α-olefin is not particularly limited, and examples thereof include α-olefins having 4 to 8 carbon atoms such as 1-butene, 4-methyl-1-pentene, 1-hexene, and 1-octene. Known polyethylene resins such as low-density polyethylene resin, medium-density polyethylene resin, and linear low-density polyethylene resin can be used. Among these, from the viewpoint of making it even more difficult for damage such as holes or tears to occur even when films rub against each other, linear low-density polyethylene resin (LLDPE) (a copolymer of ethylene and 1-hexene or a copolymer of ethylene and 1-octene) is preferred, and linear low-density polyethylene resin having a density of 0.910 to 0.925 g / cm is more preferred.

[0071] Films and sheets containing starch, a biomass material, or polylactic acid are also known. These can be selected and used appropriately depending on the application.

[0072] The biomass film may be a laminate of multiple biomass films, or a laminate of a conventional petroleum-based film and a biomass film. These biomass films may be unstretched or stretched, and their manufacturing method is not limited. The thickness of the base film is also not particularly limited, but is usually within the range of 1 to 500 μm. The printing surface of the substrate film is preferably subjected to a corona discharge treatment, and may be vapor-deposited with aluminum, silica, alumina, or the like.

[0073] (Integrated packaging film) The liquid printing ink of the present invention is particularly suitable as a printing ink for heat-shrinkable films used as integrated packaging films. Examples of resins used in heat-shrinkable films include one or a mixture of two or more selected from polyester resins such as polyethylene terephthalate resins and polylactic acid resins, polyolefin resins such as polyethylene resins and polypropylene resins, and thermoplastic resins such as polystyrene resins, polyvinyl chloride resins, and polyamide resins. Of these, resin films such as polyester resins, polyolefin resins, and polystyrene resins are often used from the viewpoint of shrink properties, etc. The liquid printing ink of the present invention has particularly good adhesion to polyolefin resins, so polyolefin resin films are preferred, and polyethylene resins and polypropylene resins are particularly preferred. In addition, biomass polyester resin films such as biomass polyethylene terephthalate resin films using the aforementioned biomass polyethylene terephthalate resins, etc., and biomass polyolefin resin films such as biomass polyethylene resin films using the aforementioned biomass polyethylene resins, etc., may also be used and are preferred. The heat-shrinkable film may be a single-layer film or a multi-layer film having a plurality of layers. In the case of a multi-layer film, the back surface may have a heat-sealable layer.

[0074] The thickness of the heat-shrinkable film is not particularly limited, but is preferably 5 to 120 μm, more preferably 7 to 100 μm, and particularly preferably 10 to 80 μm, from the viewpoints of strength, rigidity, shrink properties, economy, etc. The heat-shrinkable film is preferably transparent (colorless and transparent or colored and transparent), more preferably colorless and transparent, so that the printed layer of the liquid printing ink of the present invention can be seen through it.

[0075] In order to exhibit good heat shrinkability, the heat-shrinkable film is preferably stretched in at least one direction (uniaxial stretching), and particularly preferably biaxially stretched. The stretching temperature varies depending on the type of resin constituting the film, but is, for example, 60 to 130°C. The stretching ratio is preferably about 2 to 8 times in the main stretching direction in the case of a uniaxially stretched film, and about 2 to 8 times in both one direction and the other direction perpendicular to the one direction in the case of a biaxially stretched film. The stretching method that can be used includes a roll method, a tenter method, a tube method, and the like.

[0076] The heat shrinkage percentage of the heat-shrinkable film is 20% or more in the main stretching direction for a uniaxially stretched film, and 20% or more in both directions (one direction and the other direction) for a biaxially stretched film, preferably 30 to 80%, and particularly preferably 40 to 80% (heat treatment conditions: immersion in 90°C warm water for 10 seconds).For a uniaxially stretched film, the heat shrinkage percentage in the direction perpendicular to the main stretching direction is preferably -3 to 15%, more preferably -1 to 10%, and particularly preferably -1 to 5% (heat treatment conditions: same as above).

[0077] If necessary, an ink-receptive layer may be provided on the heat-shrinkable film to facilitate printing. As described above, the liquid printing ink of the present invention can improve adhesion and blocking resistance even on biaxially oriented polypropylene film that has not been subjected to corona discharge treatment, thereby making it possible to maximize the effects of the present invention. [Example]

[0078] The present invention will be explained in more detail with reference to examples. Hereinafter, "parts" and "%" are all based on mass. All parts other than the organic solvent indicate the amount of solids.

[0079] Example 1 A black liquid printing ink was prepared by kneading 7 parts of a commercially available chlorinated polypropylene resin with a solids content of 30% containing toluene as the chlorinated polyolefin resin, 5 parts of a vinyl chloride resin, 10 parts of carbon black (manufactured by Orionen Ginniad Carbons Co., Ltd.), 2 parts of NEOCITE F-896 (manufactured by Konan Kasei Co., Ltd.) as a rosin-modified maleic acid resin, 3 parts of polyethylene wax (manufactured by Gifu Ceramics Co., Ltd.), 2.5 parts of soybean oil-derived J-lecithin CL (CAS No. 8002-43-5, manufactured by J-Oil Mills Co., Ltd.) as a phospholipid, and 47 parts of toluene, 15 parts of ethyl acetate, 5 parts of isopropyl alcohol, and 5 parts of methyl ethyl ketone as organic solvents, for a total of 101.5 parts.

[0080] [Examples 2 and 3, Comparative Examples 1 and 2] Black liquid printing inks were prepared in the same manner as in Example 1 according to the formulations shown in Table 1.

[0081] [Manufacturing method for film prints Part 1] The inks listed in Table 1 were applied to substrate 1: biaxially oriented polypropylene film (thickness 15 μm) that had not been subjected to corona discharge treatment, using bar coater #10, and left for 24 hours to produce printed materials for Examples 1 to 3 and Comparative Examples 1 and 2.

[0082] [Manufacturing method for film prints, part 2] The inks listed in Table 1 were applied to substrate 2: Kohjin Bio Polyset (a biomass shrink film manufactured by Kohjin Film & Chemicals, 15 μm thick) using bar coater #10 and left for 24 hours to produce printed materials for Examples 1 to 3 and Comparative Examples 1 and 2.

[0083] [Adhesion] After cellophane tape (manufactured by Nichiban Co., Ltd.) was applied to the printed surface of the resulting print, the tape was quickly peeled off, and the condition of the printed surface was visually evaluated. (Evaluation criteria) 5: The printed film does not peel off at all from the film. 4: Less than 25% of the area of ​​the printed film peels off from the film. 3: The area ratio of the printed film is 25% or more but less than 50%. 2: The area ratio of the printed film is 50% or more but less than 75%. 1: 75% or more of the printed surface area is peeled off from the film.

[0084] [Kneading resistance] The ink surfaces of the printed materials were rubbed back and forth five times, and the state of ink absorption was visually evaluated. (Evaluation criteria) 5: The printed film does not peel off at all from the film. 4: Less than 25% of the area of ​​the printed film peels off from the film. 3: The area ratio of the printed film is 25% or more but less than 50%. 2: The area ratio of the printed film is 50% or more but less than 75%. 1: 75% or more of the printed surface area peels off from the film.

[0085] [Scratch resistance] The ink surface of the printed matter was rubbed with a fingernail 20 times, and the state of ink absorption was visually evaluated. (Evaluation criteria) 5: The printed film does not peel off at all from the film. 4: Less than 25% of the area of ​​the printed film peels off from the film. 3: The area ratio of the printed film is 25% or more but less than 50%. 2: The area ratio of the printed film is 50% or more but less than 75%. 1: 75% or more of the printed surface area peels off from the film.

[0086] [Blocking resistance] The ink surfaces of the printed materials were placed together and left for one day in a blocking tester under conditions of pressure: 0.5 MPa, temperature: 40°C, and humidity: 80%, and after the test, the peeling properties and condition of the surfaces were evaluated. (Evaluation criteria) 5: When peeling the printed surfaces apart, they peel off without resistance and there are no particular problems with the surface. 4: There is some resistance when peeling the printed surfaces apart, but there are no particular problems with the surface. 3: When peeling the printed surfaces apart, there is resistance and it can be seen that the surfaces are slightly stuck together. 2: When peeling the printed surfaces apart, there is a lot of resistance and it is clear that the surfaces are stuck together. 1: When peeling the printed surfaces apart, they stick together and do not come off.

[0087] The formulations of each black liquid printing ink and the evaluation results are shown in Table 1. The blank spaces in the table indicate that no compound was used.

[0088] [Table 1]

[0089] From the above results, it was found that the liquid printing ink of the present invention had excellent adhesion, crumpling resistance, scratch resistance and blocking resistance to heat-shrinkable films such as polyolefin resin films.

Claims

1. A liquid printing ink containing a chlorinated polyolefin resin as a main binder resin and an organic solvent, the ink containing lecithin in an amount of 5 to 20% by mass based on the total solid content of the ink, A liquid printing ink characterized by satisfying the following: (1) Contains a colorant. (2) The ink contains 0.2 to 15.0% by mass of rosin-modified maleic acid resin based on the ink solids. (3) The ink contains a vinyl-based resin or a vinyl chloride-vinyl acetate copolymer, which is another chlorinated vinyl-based resin, and the mass ratio of the chlorinated polyolefin resin to the vinyl chloride-vinyl acetate copolymer is in the range of 2:1 to 1:2, and the sum of the chlorinated polyolefin resin and the vinyl chloride-vinyl acetate copolymer is 10.0 to 50.0 mass% of the ink solids.

2. 2. A liquid printing ink according to claim 1, which contains polyethylene wax.

3. A printed matter obtained by printing with the liquid printing ink according to claim 1 or 2.

4. 3. A film for integrated packaging printed with the liquid printing ink according to claim 1 or 2.

5. 3. An integrated packaging film obtained by printing the liquid printing ink according to claim 1 or 2 on a biomass film.

Images