JP7713360B2 - Liquid printing inks, printed matter - Google Patents

Description

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

Liquid printing inks such as gravure inks and flexo inks are widely used to impart beauty and functionality to printed flexible packaging films. Traditionally, these liquid printing inks have been used in both cases, where the printed matter is laminated with various films using an adhesive and then used as a packaging material, and where the printed matter printed on film is used as is. However, in response to recent efforts to conserve resources and simplify packaging formats, there is an increasing demand to use gravure and flexo printed matter as packaging material, with the aim of reducing the amount of film derived from petroleum resources used and simplifying post-processing. In response to this, there is an increasing demand for the printing ink layer itself to have high printing properties such as scratch resistance, adhesion, abrasion resistance, blocking resistance, and slippage.

Moreover, in recent years, there has been a demand for biomass packaging materials, and printing inks used on packaging materials are also being required to use biomass materials rather than 100% petroleum-derived materials. There is also a growing movement to improve the printing properties themselves by using biomass materials.

As a method for improving print properties required for the printing ink layer itself, such as scratch resistance, adhesion, abrasion resistance, blocking resistance, and slippage, a method of adding a small amount of wax, such as a hydrocarbon wax or a fatty acid amide wax, is known. For example, Patent Document 1 discloses a gravure ink that contains a binder resin (A) and a hydrocarbon wax (B), in which (1) the hardness (penetration) of the hydrocarbon wax (B) at 25° C. as specified in Japanese Industrial Standard JIS K 2207 is 0.5 to 12, and (2) the hydrocarbon wax (B) is contained in an amount of 0.1 to 2.5 mass % relative to 100 mass % of the gravure ink.
However, the hydrocarbon waxes and fatty acid amide waxes disclosed therein are not biomass raw materials.

See JP 2018-53014 A

The problem that this invention aims to solve is to provide a liquid printing ink that has high printing properties in the printing ink layer itself, such as scratch resistance, adhesion, abrasion resistance, blocking resistance, and slippage, and is improved with biomass raw materials.

As a result of intensive research by the inventors to solve the above problems, the present invention has been completed based on the discovery that the above problems can be solved by using a liquid printing ink for printing on paper or plastic substrates that contains specific amounts of a binder resin (A) and a specific wax (B).

That is, the present invention provides a liquid printing ink for printing on a paper substrate or a plastic substrate, the liquid printing ink comprising a binder resin (A) and a wax (B) and satisfying the following (1) and (2):
(1) The wax (B) contains rice bran wax (B1) and carnauba wax (B2).
(2) The total amount of rice bran wax (B1) and carnauba wax (B2) is 0.5 to 10.0 mass% based on the total solids content of the ink.

The present invention also provides a liquid printing ink for surface printing.

The present invention also provides a liquid printing ink that further contains an olefin wax (B3).

The present invention also provides a liquid printing ink in which the mass ratio (B1)/(B2) of rice bran wax (B1) to carnauba wax (B2) is within the range of (B1)/(B2) = 1/10 to 2/1.

The present invention also provides a liquid printing ink to which glycerin acetate fatty acid ester is added in an amount of 0.8 to 12.0 mass % based on the total solids content of the ink.

The present invention also provides a liquid printing ink in which the binder resin (A) is an acrylic resin (A1), a polyurethane resin (A2), a cellulose resin (A3), a chlorinated vinyl resin (A4), or a rosin resin (A5).

The present invention also provides a printed matter printed with the liquid printing ink on a paper substrate or a plastic substrate.

The present invention also provides an integrated packaging film printed with the liquid printing ink on a heat-shrinkable plastic substrate.

The present invention also provides a printed matter printed with the liquid printing ink on a plastic substrate containing biomass raw materials.

The present invention also provides an integrated packaging film printed with the liquid printing ink on a heat-shrinkable biomass plastic substrate.

The liquid printing ink of the present invention has high printing properties such as scratch resistance, adhesion, abrasion resistance, blocking resistance, and slippage in the printed ink layer itself, which are improved by using biomass raw materials.

(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 an 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.
In the present invention, the surface printing ink refers to an ink used for printed matter that is distributed with the printed surface exposed after printing on a paper or film substrate. Such surface printing inks are often used for shrink films, integrated packaging films, and bread packaging films, which are specific applications of the present invention. On the other hand, reverse printing ink is also called lamination ink, and refers to an ink used for printed matter that is distributed with the printed surface covered with paper or film after printing on a paper or film substrate, and the printed surface is not directly exposed. Since there is no possibility of direct contact with food, it is often used as an ink for retort packaging, etc.

First, the liquid printing ink of the present invention is a liquid printing ink for printing on a paper substrate or a plastic substrate, which contains a binder resin (A) and a wax (B) and is characterized in that it satisfies the following (1) and (2):
(1) The wax (B) contains rice bran wax (B1) and carnauba wax (B2).
(2) The total amount of rice bran wax (B1) and carnauba wax (B2) is 0.5 to 10.0 mass% based on the total solids content of the ink.

(Binder Resin (A))
The binder resin (A) used in the present invention is not particularly limited as long as it is a binder resin used in liquid inks that are applied to printing methods using printing plates, such as ordinary gravure inks or flexographic inks. However, it is preferable to use, as the main binder resin, an acrylic resin (A1), a polyurethane resin (A2), a cellulose resin (A3), a chlorinated vinyl resin (A4), or a rosin resin (A5), among others, because they have excellent scratch resistance, adhesion, abrasion resistance, blocking resistance, slippage, etc., with respect to paper substrates or plastic substrates, which is the subject of the present invention.

(Acrylic resin (A1))
The acrylic resin is not particularly limited as long as it is a copolymer of a polymerizable monomer having a (meth)acrylic acid ester as a main component. Examples of the polymerizable monomer 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 not particularly limited, and those obtained by known bulk polymerization, solution polymerization, emulsion polymerization, suspension polymerization, and the like can be used.
The weight average molecular weight of the acrylic resin is preferably in the range of 5,000 to 200,000, and more preferably in the range of 10,000 to 100,000.
The amount of the acrylic resin added is 1.0 to 70.0% by mass, preferably 5.0 to 50.0% by mass, based on the ink solids.

(Polyurethane resin (A2))
The polyurethane resin is not particularly limited as long as it is a polyurethane resin obtained by reacting a polyol with a polyisocyanate. As the polyol, for example, various known polyols generally used in the production of polyurethane resins can be used, and one or more kinds may be used in combination. For example, 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, dipropionate, etc. 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 polyvalent carboxylic acids such as pyromellitic acid or their anhydrides; polyester polyols (3) obtained by ring-opening polymerization of cyclic ester compounds, for example lactones such as polycaprolactone, polyvalerolactone, 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.

Examples of polyisocyanates include various known aromatic diisocyanates, aliphatic diisocyanates, and alicyclic diisocyanates that are commonly 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, etc. anate, 1,4-dimethyl-2,5-phenylene diisocyanate, diethylbenzene diisocyanate, diisopropylbenzene diisocyanate, 1-methyl-3,5-diethylbenzene diisocyanate, 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, Aromatic polyisocyanates such as 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; tetramethylene diisocyanate, hexamethylene diisocyanate, dodecamethylene diisocyanate, trimethylhexamethylene diisocyanate, and 1,3-cyclopentylene diisocyanate. , 1,3-cyclohexylene diisocyanate, 1,4-cyclohexylene diisocyanate, 1,3-di(isocyanatemethyl)cyclohexane, 1,4-di(isocyanatemethyl)cyclohexane, lysine diisocyanate, isophorone diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, 2,4'-dicyclohexylmethane diisocyanate, 2,2'-dicyclohexylmethane diisocyanate, 3,3'-dimethyl-4,4'-dicyclohexylmethane diisocyanate, and other aliphatic or alicyclic polyisocyanates can be used. These polyisocyanates may be used alone or in combination of two or more. Among these, these diisocyanate compounds can be used alone or in a mixture of two or more.

Chain extenders can also be used. Examples of chain extenders include ethylenediamine, propylenediamine, hexamethylenediamine, diethylenetriamine, triethylenetetramine, isophoronediamine, dicyclohexylmethane-4,4'-diamine, and the like. In addition, 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, can also be used. These chain extenders can be used alone or in combination of two or more.

Furthermore, a monovalent active hydrogen compound can be used as a terminal blocking agent for the purpose of stopping 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 a carboxyl group into the polyurethane resin, amino acids such as glycine and L-alanine can be used as a reaction stopping agent. These terminal blocking agents can be used alone or in combination of two or more.
The weight average molecular weight of the polyurethane resin is preferably in the range of 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 1.0 to 60.0% by mass, and more preferably 5.0 to 40.0% by mass, based on the ink solids.

(Cellulose-based resin (A3))
Examples of cellulose resins include cellulose acetate propionate, cellulose acetate butyrate and other cellulose ester resins, nitrocellulose (also called soluble cellulose), hydroxyalkylcellulose, and carboxyalkylcellulose. 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, the cellulose-based resin is preferably cellulose acetate propionate, cellulose acetate butyrate, or nitrocellulose. Particularly preferred are cellulose acetate propionate and cellulose acetate butyrate. The molecular weight is preferably 5,000 to 200,000 in weight average molecular weight, more preferably 10,000 to 50,000. Also, the glass transition temperature is preferably 120°C to 180°C. When used in combination with the polyurethane resin (A2) of the present invention, it is expected that the blocking resistance, scratch resistance, and other physical properties of the ink film will be improved.
Nitrocellulose (nitrocellulose) is preferably obtained by reacting natural cellulose with nitric acid to replace three hydroxyl groups in the six-membered ring of the anhydrous glucopyranose group in the natural cellulose with nitric acid to produce a nitric acid ester.

The use of nitrocellulose (nitrocellulose) provides high dispersibility in pigments, and is therefore particularly suitable for use as a coating agent for surface printing, as it can improve the strength of the printing ink coating. 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.

The amount of cellulose acetate propionate or cellulose acetate butyrate added is 1.0 to 40.0% by mass, preferably 3.0 to 20.0% by mass, based on the ink solids.
On the other hand, nitrocellulose can also be used as a biomass feedstock.

(Chlorinated vinyl resin (A4))
In the chlorinated vinyl resin, the vinyl resin may be a homopolymer or copolymer of a compound having a vinyl group, and representative 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, vinyl chloride-various vinyl ether copolymers, and blends thereof, as well as 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.
Among these, vinyl chloride-vinyl acetate copolymer is particularly preferred.

The vinyl chloride-vinyl acetate copolymer is not particularly limited and any known copolymer can be used, but among them, a vinyl chloride-vinyl acetate copolymer having a hydroxyl group is preferable, and a vinyl chloride-vinyl acetate copolymer having a hydroxyl group with a hydroxyl value of 50 to 200 mg KOH/g and a content ratio of the vinyl chloride component in the copolymer of 80 to 95% by weight is even more preferable.

The vinyl chloride-vinyl acetate copolymer having hydroxyl groups used in the present invention can be obtained by two methods. One is obtained by copolymerizing vinyl chloride monomer, vinyl acetate monomer, and vinyl alcohol in an appropriate ratio. The other is obtained by copolymerizing vinyl chloride and vinyl acetate, and then partially saponifying the vinyl acetate. The properties of the resin coating and the resin dissolution behavior of the vinyl chloride-vinyl acetate copolymer having hydroxyl groups are determined by the monomer ratio of vinyl chloride, vinyl acetate, and vinyl alcohol. That is, vinyl chloride imparts strength and hardness to the resin coating, vinyl acetate imparts adhesion and flexibility, and vinyl alcohol imparts good solubility in polar solvents.

As for the monomer ratio of the vinyl chloride-vinyl acetate copolymer having hydroxyl groups, for example, 80 to 95 parts by weight of vinyl chloride per 100 parts by weight of the vinyl chloride-vinyl acetate copolymer having hydroxyl groups is more preferable since it balances blocking resistance and adhesion. If it is 80 parts by weight or more, the toughness of the resin coating can be maintained and blocking resistance can be ensured. If it is 95 parts by weight or less, the resin coating does not become too hard and adhesion is less likely to decrease. In addition, the hydroxyl value obtained from vinyl alcohol is preferably 50 to 200 mgKOH/g. If it is 50 mgKOH/g or more, the solubility in polar solvents is good and the printability is easily stabilized. If it is 200 mgKOH/g or less, the lamination suitability can be maintained well.

The vinyl acetate resin is a vinyl acetate polymer, which is a homopolymer of vinyl acetate monomer, or a copolymer of vinyl acetate monomer and a polymerizable unsaturated monomer. Examples of unsaturated monomers include long-chain (meth)acrylic monomers such as alkyl (meth)acrylate monomers, such as 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.

The molecular weight of the vinyl resin is preferably a weight average molecular weight of 5,000 to 100,000, and more preferably 10,000 to 70,000.

The amount of vinyl resin added is 1.0 to 70.0% by mass, preferably 5.0 to 50.0% by mass, based on the ink solids.

Furthermore, as the chlorinated vinyl resin used in the present invention, a vinyl resin obtained by chlorinating the above-mentioned vinyl resin (also called a chlorinated vinyl resin) may be used.
The chlorination of vinyl resins can be carried out by known methods, for example, a method in which a vinyl resin is dispersed or dissolved in a medium such as water or 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 irradiation of ultraviolet light.
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 the like, and chlorinated ethylene-vinyl acetate copolymers obtained by chlorinating ethylene-vinyl acetate copolymers.
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 further preferably 7,000 to 50,000. The chlorine content, which indicates the mass percentage of chlorine atoms in 100 mass% of the resin, is often in the range of 15 to 45 mass%.
The chlorinated vinyl resin is contained in the ink solids in an amount of 1.0 to 70% by mass, preferably 5 to 50% by mass.

Commercially available chlorinated vinyl resins may be used, including chlorinated polyolefin resins, chlorinated ethylene vinyl alcohol (EVA), and chlorinated ethylene-vinyl acetate copolymers, such as the Superchlorine series from Nippon Paper Industries Co., Ltd.

(Rosin-based resin (A5))
The rosin-based resin used in the present invention can be any rosin and/or rosin derivative that is widely used for printing inks, without any particular limitations. Specifically, rosin or rosin derivatives are rosins or carboxyl group-containing derivatives thereof. Rosins include gum rosin, wood rosin, tall oil rosin, disproportionated rosin, hydrogenated rosin, and polymers thereof. 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 the rosin resin added is preferably 0.1 to 20.0% by mass, and more preferably 0.2 to 15.0% by mass, based on the ink solids.

In the present invention, it is preferable to use a rosin-modified maleic acid resin, which is a maleic acid derivative of rosin, in combination. 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 mgKOH/g or more and 320 mgKOH/g or less, and more preferably has an acid value of 100 mgKOH/g or more and 320 mgKOH/g or less.
The amount of the rosin-modified maleic acid resin added is preferably 0.1 to 20.0% by mass, more preferably 0.2 to 15.0% by mass, based on the ink solids content.

Examples of commercially available rosin-based resins include Malquid No. 1, 2, 5, 6, 8, 31, 32, 33, 34, and 3002 manufactured by Arakawa Chemical Industries, Ltd., and Harimamac R-80, T-80, R-100, M-453, M-130A, 135GN, 145P, R-120AH, Haritac 4851, 4821, 4740, and 28JA manufactured by Harima Chemical Industries, Ltd.
These rosin-based resins can also be used as biomass raw materials.
Specific examples of rosin-modified fumaric acid resins include Arochem 475 (trade name) manufactured by Nippon Shokubai Co., Ltd.

(Polyamide resin)
In the liquid printing ink of the present invention, a polyamide resin may be used as the binder resin. The polyamide resin may be, for example, a thermoplastic polyamide soluble in an organic solvent, which can be obtained 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 and an aliphatic and/or aromatic polyamine is preferable, and further, a polyamide resin containing a portion of primary and secondary monoamines is preferable.
Examples of 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 mass or more in the polyamide resin) are preferred. Here, polymerized fatty acid is obtained by cyclization reaction of unsaturated fatty acid, and includes monobasic fatty acid, dimerized polymerized fatty acid (dimer acid), trimerized polymerized fatty acid, and the like. In addition, 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, and those obtained from oleic acid and linoleic acid are 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 cyclohexane carboxylic acid.

Examples of the polyamine include polyamines, primary and secondary monoamines, etc. Examples of the polyamines used in the polyamide resin include aliphatic diamines such as ethylenediamine, propylenediamine, hexamethylenediamine, and methylaminopropylamine, and aliphatic polyamines such as diethylenetriamine and triethylenetetramine, and examples of the alicyclic polyamines include cyclohexylenediamine and isophoronediamine. Examples of the aromatic aliphatic polyamines include xylylenediamine, and examples of the aromatic polyamines include phenylenediamine and diaminodiphenylmethane. Examples of the primary and secondary monoamines include n-butylamine, octylamine, diethylamine, monoethanolamine, monopropanolamine, diethanolamine, and dipropanolamine.
The amount of polyamide resin added is 0.1 to 15.0% by mass, preferably 0.5 to 3.0% by mass, based on the ink solids.

Wax (B)
In the liquid printing ink of the present invention, the wax (B) essentially contains the following (1) and (2):
(1) The wax (B) contains rice bran wax (B1) and carnauba wax (B2).
(2) The total amount of rice bran wax (B1) and carnauba wax (B2) is 0.5 to 10.0 mass% based on the total solids content of the ink.
The rice bran wax is not particularly limited as long as it is a wax derived from rice bran, which is a light brown powder made from the outer husk and germ of rice that is produced when brown rice is polished.
The carnauba wax includes natural carnauba wax collected from the leaves of the carnauba palm of the palm family, as well as refined products and derivatives thereof, and also includes those modified with additives, etc. According to a preferred embodiment, the carnauba wax has a melting point of 80° C. or higher and 90° C. or lower, an acid value of 10 mg KOH/g or lower, and a saponification value of 78 mg KOH/g or higher and 88 mg KOH/g or lower.
Both rice bran wax and carnauba wax can be used as biomass raw materials.
The total amount of rice bran wax (B1) and carnauba wax (B2) must be 0.5 to 10.0 mass % based on the total solids content of the ink.
When the total amount of the rice bran wax (B1) and the carnauba wax (B2) is 0.5% by mass or more, scratch resistance, cellophane tape adhesion, abrasion resistance, and blocking properties can all be achieved.
When the total amount of the rice bran wax (B1) and the carnauba wax (B2) is 10% by mass or less, the plate fogging resistance and tone reproducibility tend to be maintained.

In addition to the rice bran wax and carnauba wax, olefin waxes such as polyethylene wax and polypropylene wax, and hydrocarbon waxes such as Fischer-Tropsch wax, paraffin wax and microcrystalline wax may be used in appropriate amounts in combination as necessary.
Among these, olefin waxes such as polyethylene wax and polypropylene wax are preferred.
The amount of the olefin wax added is preferably within a range of 0.5 to 5.0% by mass based on the total solid content of the ink.

(Glycerol acetate fatty acid ester)
Furthermore, it is preferable to add glycerin acetate fatty acid ester to the liquid printing ink of the present invention. Glycerin acetate fatty acid ester is a plasticizer with a high biomass content that is made mainly from vegetable oil and is effective in preventing ink cracking during thermal shrinkage, and is therefore particularly preferable for liquid printing inks used for shrink films for integrated packaging, for example.
The glycerin acetate fatty acid ester is preferably added in an amount of 0.8 to 12.0% by mass based on the total solid content of the ink.
When the content is 0.8% by mass or more relative to the total solids content of the ink, ink cracking due to thermal shrinkage caused by heating after printing tends to be prevented, and when the content is 12% by mass or less, the tendency for blocking properties to decrease can be suppressed.
An example of the glycerin acetate fatty acid ester is "BIOCIZER (trade name) (main component: glycerin diacetomonolaurate)" manufactured by Riken Vitamin Co., Ltd. BIOCIZER uses fatty acids derived from palm kernel oil. The term "main component" means that it contains 50% by mass or more.

(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-based 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 various organic solvents such as 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, di) methyl ether, ethylene glycol (mono, di) ethyl ether, ethylene glycol monopropyl ether, ethylene glycol monoisopropyl ether, monobutyl ether, diethylene glycol (mono, di) methyl ether, diethylene glycol (mono, di) ethyl ether, diethylene glycol monoisopropyl ether, diethylene glycol monobutyl ether, triethylene glycol (mono, di) methyl ether, propylene glycol (mono, di) methyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, and dipropylene glycol (mono, di) methyl ether. These can be used alone or in combination of two or more.

In addition, from the standpoint 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 use aromatic solvents such as toluene or ketone-based solvents such as methyl ethyl ketone.

Among them, from the viewpoint of solubility in each binder resin, a mixture of isopropyl alcohol, ethyl acetate, and normal propyl acetate is more preferable. In addition, glycol ethers can be added in an amount of less than 10% by mass of the ink solid content for drying adjustment.

(Coloring Agent)
The liquid printing ink of the present invention can be used as a varnish for adjusting the concentration of ink that does not contain a colorant and as an overprint varnish, or it can be used as an ink containing a colorant for use in design printing, etc., for the purpose of imparting cosmetic properties, etc., by including a colorant.
The colorant is preferably a pigment, and examples of the pigment include inorganic pigments and organic pigments used in general inks, paints, and recording agents, etc. Examples of organic pigments include soluble azo-based, insoluble azo-based, azo-based, phthalocyanine-based, halogenated phthalocyanine-based, anthraquinone-based, anthanthrone-based, dianthraquinonyl-based, anthrapyrimidine-based, perylene-based, perinone-based, quinacridone-based, thioindigo-based, dioxazine-based, isoindolinone-based, quinophthalone-based, azomethine azo-based, flavanthrone-based, diketopyrrolopyrrole-based, isoindoline-based, indanthrone-based, and carbon black-based pigments. In addition, examples of the pigments include carmine 6B, lake red C, permanent red 2B, disazo yellow, pyrazolone orange, carmine FB, chromophthal yellow, chromophthal 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. In addition, both non-acid-treated pigments and acid-treated pigments can be used. Specific examples of preferred organic pigments are listed below.

Examples of black pigments include C.I. Pigment Black 1, C.I. Pigment Black 6, C.I. Pigment Black 7, C.I. Pigment Black 9, and C.I. Pigment Black 20.

Examples of indigo pigments include C.I. Pigment Blue 15, C.I. Pigment Blue 15:1, C.I. Pigment Blue 15:2, C.I. Pigment Blue 15:3, C.I. Pigment Blue 15:4, C.I. Pigment Blue 15:5, C.I. Pigment Blue 15:6, C.I. Pigment Blue 16, C.I. Pigment Blue 17:1, C.I. Pigment Blue 22, C.I. Pigment Blue 24:1, C.I. Pigment Blue 25, C.I. Pigment Blue 26, C.I. Pigment Blue 60, C.I. Pigment Blue 61, C.I. Pigment Blue 62, C.I. Pigment Blue 63, C.I. Pigment Blue 64, C.I. Pigment Blue 75, C.I. Pigment Blue 79, C.I. Pigment Blue 80, etc.

Examples of green pigments include C.I. Pigment Green 1, C.I. Pigment Green 4, C.I. Pigment Green 7, C.I. Pigment Green 8, C.I. Pigment Green 10, and C.I. Pigment Green 36.

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

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

Examples of yellow pigments include C.I. Pigment Yellow 1, C.I. Pigment Yellow 3, C.I. Pigment Yellow 12, C.I. Pigment Yellow 13, C.I. Pigment Yellow 14, Pigment Yellow 17, C.I. Pigment Yellow 24, C.I. Pigment Yellow 42, C.I. Pigment Yellow 55, C.I. Pigment Yellow 62, C.I. Pigment Yellow 65, C.I. Pigment Yellow 74, C.I. Pigment Yellow 83, C.I. Pigment Yellow 86, C.I. Pigment Yellow 93, C.I. Pigment Yellow 94, C.I. Pigment Yellow 95, C.I. Pigment Yellow 109, C.I. Pigment Yellow 110, C.I. Pigment Yellow 117, C.I. Pigment Yellow 120, Pigment Yellow 125, C.I. Pigment Yellow 128, C.I. Pigment Yellow 129, C.I. Pigment Yellow 137, C.I. Pigment, Yellow 138, C.I. Pigment Yellow 139, C.I. Pigment Yellow 147, C.I. Pigment Yellow 148, C.I. Pigment Yellow 150, C.I. Pigment Yellow 151, C.I. Pigment Yellow 153, C.I. Pigment Yellow 154, C.I. Pigment Yellow 155, C.I. Pigment Yellow 166, C.I. Pigment Yellow 168, C.I. Examples of the pigments include C.I. Pigment Yellow 174, C.I. Pigment Yellow 180, C.I. Pigment Yellow 185, and C.I. Pigment Yellow 213.

Examples of orange pigments include C.I. Pigment Orange 5, C.I. Pigment Orange 13, C.I. Pigment Orange 16, C.I. Pigment Orange 34, C.I. Pigment Orange 36, C.I. Pigment Orange 37, C.I. Pigment Orange 38, C.I. Pigment Orange 43, C.I. Pigment Orange 51, C.I. Pigment Range 55, C.I. Pigment Orange 59, C.I. Pigment Orange 61, C.I. Pigment Orange 64, C.I. Pigment Orange 71, and C.I. Pigment Orange 74.

Examples of brown pigments include C.I. Pigment Brown 23, C.I. Pigment Brown 25, and C.I. Pigment Brown 26.

Among them, preferred pigments include C.I. Pigment Black 7 as a black pigment,
As indigo pigments, C.I. Pigment Blue 15, C.I. Pigment Blue 15:1, C.I. Pigment Blue 15:2, C.I. Pigment Blue 15:3, C.I. Pigment Blue 15:4, C.I. Pigment Blue 15:6,
As a green pigment, C.I. Pigment Green 7,
Red pigments include C.I. Pigment Red 57:1, C.I. Pigment Red 48:1, C.I. Pigment Red 48:2, C.I. Pigment Red 48:3, C.I. Pigment Red 146, C.I. Pigment Red 242, C.I. Pigment Red 185, C.I. Pigment Red 122, C.I. Pigment Red 178, C.I. Pigment Red 149, C.I. Pigment Red 144, C.I. Pigment Red 166,
As purple pigments, C.I. Pigment Violet 23, C.I. Pigment Violet 37,
Yellow pigments include C.I. Pigment Yellow 83, C.I. Pigment Yellow 14, C.I. Pigment Yellow 180, C.I. Pigment Yellow 139,
Orange pigments include C.I. Pigment Orange 38, C.I. Pigment Orange 13, C.I. Pigment Orange 34, C.I. Pigment Orange 64,
It is preferable to use at least one or two or more selected from these groups.

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, the use of 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, and from the standpoint of printing performance, the titanium oxide is preferably treated with silica and/or alumina.

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, and zircon. Aluminum is in powder or paste form, but it is preferable to use it in paste form from the standpoint of ease of handling and safety, and whether leafing or non-leafing is used is selected appropriately from the standpoint of brightness and concentration.

The pigment is preferably contained in an amount sufficient to ensure the concentration and coloring power 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 kinds.

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

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, a pigment dispersion is produced in which a pigment is dispersed in an organic solvent using a binder resin, and the resulting pigment dispersion can be mixed with other compounds, etc., as necessary, to produce the ink.

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 dispersing machine, the packing rate of the grinding media, the dispersion treatment time, the discharge speed of the pigment dispersion, the viscosity of the pigment dispersion, etc. As the dispersing machine, for example, a commonly used roller mill, ball mill, pebble mill, attritor, sand mill, etc. can be used.
When air bubbles or unexpectedly large particles are contained in the ink, they degrade the quality of the printed matter, so it is preferable to remove them by filtration, etc. As the filter, a conventionally known filter can be used.

The viscosity of the ink produced by the above method is preferably in the range of 10 mPa·s or more from the viewpoint of preventing sedimentation of the pigment and adequately dispersing it, and 1000 mPa·s or less from the viewpoint of workability during ink production and printing. The above viscosity is measured at 25° C. using a B-type viscometer manufactured by Tokimec Co., Ltd.
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.

(Printed matter and laminates)
The liquid printing ink of the present invention is printed on any substrate to obtain a printed matter. The substrate used in the present invention is not particularly limited, and may be a paper or plastic substrate normally used in the gravure/flexographic printing field, or a soft packaging substrate used in the food packaging field. For example, the paper may be a wood-free paper used for printing on packaging materials and packages for cosmetics, beverages, medicines, toys, equipment, etc., kraft paper, pure white roll paper, glassine paper, parchment paper, Manila cardboard, white cardboard, coated paper, art paper, imitation paper, thin paper, thick paper, polyethylene coated paper, and various synthetic papers.

Examples of the film substrate include polyamide resins such as nylon 6, nylon 66, and nylon 46; polyester resins such as polyethylene terephthalate (hereinafter sometimes referred to as 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); polyolefin resins such as polypropylene and polyethylene, polyimide resins, polyarylate resins, and mixtures thereof; and films and laminates thereof made of thermoplastic resins, among which films made of polyethylene terephthalate (PET), polyester, polyamide, polyethylene, and polypropylene can be preferably used. These substrate films may be unstretched or stretched films, and the manufacturing method is not limited. The thickness of the substrate film is also not particularly limited, but it is usually sufficient to be in the range of 1 to 500 μm.
The printing surface of the substrate film is preferably subjected to a corona discharge treatment, and aluminum, silica, alumina, etc. may be vapor-deposited thereon.
Furthermore, if these substrates are plastic substrates containing biomass raw materials, the biomass conversion ratio can be further increased due to the synergistic effect with each of the biomass raw materials such as rice bran wax, carnauba wax, cellulose fiber resin, rosin-modified fumaric acid resin, and glycerin acetate fatty acid ester.

(Integrated packaging film)
The liquid printing ink of the present invention may be used as a printing ink for heat shrinkable films used as integrated packaging films.
Examples of resins used in the heat shrinkable film 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. Among these, resin films of polyester resins, polyolefin resins, polystyrene resins, etc. are often used from the viewpoint of shrink properties, etc. The liquid printing ink of the present invention has good adhesion to polyolefin resins in particular, so polyolefin resin films are preferred, and polyethylene resins and polypropylene resins are particularly preferred.
The heat shrinkable film may be a single layer film or a multilayer film having a plurality of layers. In the case of a multilayer film, the multilayer film may have a heat seal layer as a layer constituting the back surface.

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

In order to exhibit good heat shrinkability, the heat shrinkable film is preferably stretched in at least one direction (uniaxial stretching), and is 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 for uniaxially stretched films, and in both one direction and the other direction perpendicular to the one direction for biaxially stretched films. The stretching method that can be used is a roll method, a tenter method, a tube method, etc.

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

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 enabling the effects of the present invention to be maximized.

The present invention will be explained in more detail with reference to examples. In the following, "parts" and "%" are all based on mass. In addition, all parts other than the organic solvent indicate the solid content.

(Acrylic resin)
The acrylic resin used was "Product name: Acrydic WCL-1419, weight average molecular weight: 35,000" manufactured by DIC Corporation.

(Polyurethane resin)
As the polyurethane resin, "Product name: Burnock ECL-341, weight average molecular weight 85,000" manufactured by DIC Corporation was used.

(Preparation of Cellulose Acetate Propionate Resin Solution Ca)
80 parts of a mixture of isopropyl alcohol/ethyl acetate/normal propyl acetate/methylcyclohexane (weight ratio of 25/25/13/10) was added to 20 parts of cellulose acetate propionate CAP482-0.5 (manufactured by Eastman Chemical Co.) and thoroughly mixed to prepare a cellulose ester resin solution Ca.

(Preparation of vinyl chloride-vinyl acetate copolymer resin solution Ev)
A vinyl chloride-vinyl acetate copolymer resin having a hydroxyl group (resin monomer composition, in mass %, vinyl chloride/vinyl acetate/vinyl alcohol=92/3/5, hydroxyl value (mg KOH)=64) was made into a 25% solution in ethyl acetate, and this was named vinyl chloride-vinyl acetate copolymer resin solution Ev.

(rosin modified fumaric acid resin)
As the rosin-modified fumaric acid resin, "Product name: Malquid No. 31, weight average molecular weight: 1200" manufactured by Arakawa Chemical Industries Co., Ltd. was used.

Example 1
A white liquid printing ink was prepared by adding 48 parts of a mixed organic solvent having a mass ratio of isopropyl alcohol: ethyl acetate: normal propyl acetate: 4:2:1 to a total of 100.01 parts of solids, which were 15.26 parts of an acrylic resin manufactured by DIC Corporation (product name: ACRYDIC WCL-1419, weight average molecular weight: 35,000), 5.09 parts of the solid content of the cellulose acetate propionate resin solution Ca, 68.49 parts of titanium oxide JR-780 (manufactured by Teika Co., Ltd.), 3.86 parts of glycerin acetate fatty acid ester as a plasticizer, 1.4 parts of polyethylene wax 1 (average particle size: 7 μ), 3.0 parts of ester wax derived from rice bran, 2.53 parts of carbamate wax compound, and 0.37 parts of spherical polyethylene wax 2 (average particle size: 10 μm) as a slipping agent.

[Examples 2 to 18 and Comparative Examples 1 to 16]
According to the formulations shown in Tables 1 to 8, each liquid printing ink was prepared in the same manner as in Example 1.
In addition, the indigo inks of Examples 12 to 18 and Comparative Examples 11 to 16 were indigo liquid printing inks using FASTGEN Blue LA5380: C.I. Pigment Blue 15, a phthalocyanine blue pigment (manufactured by DIC Corporation) instead of the titanium oxide JR-780.

(Production of printed matter)
Each of the liquid printing inks prepared above was applied to a biaxially oriented polystyrene sheet film that had not been subjected to corona discharge treatment, or a hybrid styrene sheet film, or a polyethylene terephthalate film (all 40 μm thick) using a bar coater #10, and the resulting film was left for 24 hours to produce a printed matter.

[Adhesion]
For each of the prints, cellophane tape (manufactured by Nichiban Co., Ltd.) was applied to the printed surface, and the tape was quickly peeled off, and the condition of the printed surface was visually evaluated.
(Evaluation Criteria)
7: The printed film does not peel off at all from the film.
6: Less than 5% of the area of the printed film peeled off from the film.
5: Less than 15% of the area of the printed film peeled off from the film.
4: Less than 30% of the area of the printed film peeled off from the film.
3: 30% or more and less than 50% of the area of the printed film peels off from the film.
2: 50% or more and less than 75% of the area of the printed film peels off from the film.
1: 75% or more of the area of the printed surface is peeled off from the film.

[Scratch resistance]
The printed surface of each of the printed materials was rubbed back and forth with a fingernail 20 times, and the state of ink absorption was visually evaluated.
(Evaluation Criteria)
7: The printed film does not peel off at all from the film.
6: Less than 5% of the area of the printed film peeled off from the film.
5: Less than 15% of the area of the printed film peeled off from the film.
4: Less than 30% of the area of the printed film peeled off from the film.
3: 30% or more and less than 50% of the area of the printed film peels off from the film.
2: 50% or more and less than 75% of the area of the printed film peels off from the film.
1: 75% or more of the area of the printed surface is peeled off from the film.

[Abrasion resistance]
The printed surface of each of the printed materials was rubbed with black fine paper using a commercially available Gakushin type rub fastness tester under conditions of 100 reciprocating strokes at a load of 500 g.
(Evaluation Criteria)
7: No color was transferred to the rubbed black wood-free paper.
6: The color is very light on the rubbed black wood-free paper, with a rating between "7" and "5".
5: The rubbed black wood-free paper was slightly stained, with a rating between "6" and "4".
4: The rubbed black wood-free paper was slightly colored, but within the practical range.
3: Moderate coloring of rubbed black wood-free paper, between "4" and "2".
2: Moderate coloring of rubbed black wood-free paper, between "3" and "1".
1: The color is darkly transferred to rubbed black wood-free paper.

[Blocking resistance]
The printed surfaces of each of the printed materials were placed together and left for one day in a blocking tester under conditions of a pressure of 0.5 MPa, a temperature of 50° C. and a humidity of 80%, after which the peeling properties and condition of the surfaces were evaluated.
(Evaluation Criteria)
7: When the printed surfaces were peeled off from each other, they peeled off without resistance, and there were no particular problems with the surfaces.
6: There is some resistance when peeling the printed surfaces apart, but the surface has no particular problems.
5: When peeling the printed surfaces apart, there is some resistance and it can be seen that the surfaces are slightly stuck together.
4: When peeling the printed surfaces apart, there is resistance and it can be seen that the surfaces are slightly stuck together.
3: When peeling the printed surfaces apart, there is resistance and you can see that the surfaces are stuck together.
2: When peeling the printed surfaces apart, there is considerable resistance and it is clear that the surfaces are firmly stuck together.
1: When trying to peel the printed surfaces apart, they stick together and do not come off.

[Slipperiness]
For each of the printed matters, a film 65 mm wide and 65 mm long was prepared as a test piece, and the dynamic friction coefficient between the printed surface and polyethylene terephthalate (Toyobo E5101 100 μm) was measured using a commercially available friction tester at a load of 200 g, a speed of 300 mm/min, and a running distance of 50 mm.
(Evaluation Criteria)
7: Dynamic friction coefficient 0 to less than 0.2 6: Dynamic friction coefficient 0.2 or more and less than 0.3 5: Dynamic friction coefficient 0.3 or more and less than 0.4 4: Dynamic friction coefficient 0.4 or more and less than 0.5 3: Dynamic friction coefficient 0.5 or more and less than 0.6 2: Dynamic friction coefficient 0.6 or more and less than 0.8 1: Dynamic friction coefficient 0.8 or more

[Plate fogging]
The viscosity of each of the liquid printing inks prepared above was adjusted to 16 seconds (25°C) using a Zahn cup #3 (manufactured by Rigo Co., Ltd.) with a mixed organic solvent of ethyl acetate/isopropyl alcohol = 50/50, and printing was performed on a biaxially stretched polystyrene sheet film, hybrid styrene sheet film, or polyethylene terephthalate film (all 40 μm thick) that had not been subjected to corona discharge treatment using an MD type gravure printing machine (manufactured by Fuji Machine Co., Ltd.) equipped with a laser gravure plate having a plate depth of 30 μm. The degree of dirt (plate fogging degree) of the non-printed highlight parts when printing at a printing speed of 200 m/min with a circumference of the gravure plate of 600 mmΦ was visually evaluated.
(Evaluation Criteria)
7: No stains at all on non-printed areas.
6: The stains on the non-printed areas account for less than 5% of the total area.
5: The stains on the non-printed areas account for 5% or more and less than 15% of the total area.
4: The stains on the non-printed parts account for 15% or more and less than 25% of the total area.
3: The stains on the non-printed parts account for 25% or more and less than 35% of the total area.
2: The stains on the non-printed parts account for 35% or more and less than 50% of the total area.
1: The stains on the non-printed areas account for 50% or more of the total area.

[Tone reproducibility]
The tone reproducibility was evaluated by dot gain, which was determined by comparing the area of the cell openings in the 50% dot area of the gravure plate and the area of the 50% dot area of the printed matter when 4,000 m was printed using a gravure plate with a circumference of 600 mmΦ and a speed of 200 m/min.
In gravure printing, if the dots are larger than the area of the actual cell openings, the reproduction of color tones and other aspects will be poor, so it is desirable for the dots on the print to be close to the area of the cell openings.
(Evaluation Criteria)
7: The area of the printed dots is in the range of 100% to 105% compared to the area of the cell openings.
6: The area of the printed dots is in the range of 106% to 110% compared to the area of the cell openings.
5: The area of the printed dots is in the range of 111% to 120% compared to the area of the cell openings.
4: The area of the printed dots is in the range of 121% to 130% compared to the area of the cell openings.
3: The area of the printed dots is in the range of 131% to 140% compared to the area of the cell openings.
2: The area of the printed dots is in the range of 141% to 160% compared to the area of the cell openings.
1: The area of the dots in the print is 161% or more compared to the area of the cell openings.

The formulations of each white or indigo liquid printing ink and the evaluation results are shown in Tables 1 to 8. The solid content is shown except for the organic solvent.
In the table, blank spaces indicate that no additive was added. The substrate OPS indicates a biaxially oriented polystyrene sheet film, and PET indicates a polyethylene terephthalate film.

Claims (10)

A liquid printing ink for printing on a paper substrate or a plastic substrate, comprising a binder resin (A) and a wax (B), and satisfying the following requirements (1) to (4) :
(1) The wax (B) contains rice bran wax (B1) and carnauba wax (B2).
(2) The total amount of rice bran wax (B1) and carnauba wax (B2) is 0.5 to 10.0 mass% based on the total solids content of the ink.
(3) The binder resin (A) is any one of (3-1) to (3-3).
(3-1) Contains an acrylic resin (A1) and a cellulose resin (A3).
(3-2) Contains a polyurethane resin (A2) and a cellulose-based resin (A3).
(3-3) Contains a polyurethane resin (A2), a cellulose-based resin (A3), a chlorinated vinyl-based resin (A4), and a rosin-based resin (A5).
(4) The ink contains a pigment in an amount of 10 to 90 mass % in terms of solid weight ratio. The liquid printing ink according to claim 1, which is for surface printing. The liquid printing ink according to claim 1 or 2, further comprising an olefin wax (B3). A liquid printing ink according to any one of claims 1 to 3, in which the mass ratio (B1)/(B2) of the rice bran wax (B1) to the carnauba wax (B2) is in the range of (B1)/(B2) = 1/10 to 2/1. The liquid printing ink according to any one of claims 1 to 4 further comprises 0.8 to 12.0 mass% of glycerin acetate fatty acid ester based on the total solid content of the ink. The liquid printing ink according to any one of claims 1 to 5, wherein the (3) binder resin (A) is any one of (3-1') to (3-3').
(3-1') Contains acrylic resin and cellulose acetate propionate
(3-2') Contains polyurethane resin and cellulose propionate.
(3-3') Contains polyurethane resin, cellulose propionate, vinyl chloride-vinyl acetate copolymer, and rosin-modified fumaric acid resin. A printed matter printed on a paper substrate or a plastic substrate with the liquid printing ink according to any one of claims 1 to 6. An integrated packaging film printed on a heat-shrinkable plastic substrate with the liquid printing ink described in any one of claims 1 to 6. A printed matter printed on a plastic substrate containing biomass raw materials with the liquid printing ink according to any one of claims 1 to 6. An integrated packaging film printed on a heat-shrinkable biomass plastic substrate with the liquid printing ink described in any one of claims 1 to 6.