JP7543890B2 - Liquid ink composition, and printed matter and laminate using said liquid ink composition - Google Patents

Description

The present invention relates to a liquid ink composition that can be used as a laminate gravure ink or flexographic ink for flexible packaging, and to a printed matter and a laminate that use the liquid ink composition.

Gravure ink and flexographic ink are widely used to impart beauty and functionality to printed materials. When gravure- or flexographically printed materials are used as packaging materials, particularly food packaging, they are generally laminated. In this case, various printed materials and lamination processes are used depending on the type of contents and the purpose of use.

Traditionally, printing inks using polyurethane resin and vinyl chloride-vinyl acetate copolymer resin (hereafter referred to as "PVC") as binders have been widely used for such laminated products. These resins are a combination of binders that can achieve both excellent dispersibility and high film properties, and are essential ink ingredients for achieving good printability and the various properties required of laminating inks, such as adhesion to substrates, lamination strength, and boiling retort properties.

In recent years, the use of aromatic solvents such as toluene and ketone-based solvents such as methyl ethyl ketone is being restricted due to both the hygienic nature of the printing process and the harmfulness of packaging materials. For example, Patent Document 1 describes a non-tolubricating lamination ink composition for flexible packaging that contains, as essential components, a polypropylene glycol-containing polyurethane resin and a vinyl chloride-vinyl acetate copolymer resin having hydroxyl groups.

Furthermore, legal regulations surrounding food packaging in particular are becoming stricter worldwide, and in recent years, regulations on the ingredients used in packaging and their migration into food are becoming increasingly strict. In addition, the movement away from plastic has accelerated in recent years, and demand for recyclable packaging is increasing. In the future, when developing ink products for packaging, etc., it will be necessary to design inks and packaging components using materials that are guaranteed to be safe for the human body and the environment.

In the midst of this trend, PVC is a concern as a substance that impedes the recycling of packaging due to the following issues. The first issue is related to chemical recycling. Plastic waste discharged as general waste contains various plastics, including chlorine-based resins such as polyvinyl chloride and polyvinylidene chloride. These chlorine-based resins cause corrosion of equipment and piping when hydrogen chloride is released and hydrochloric acid is generated during the thermal decomposition process of recycling. The second issue is related to thermal recycling. In a method of reusing the energy generated when waste is incinerated, if chlorine-based resins are included during incineration, environmental hormones such as dioxins are emitted, which is a problem. Therefore, there is a need to develop an ink that has the physical properties required for lamination inks without using chlorine-based materials such as PVC.

On the other hand, with the recent diversification of packaging substrates, printing inks used for decoration or surface protection are required to have high performance and adaptability to various films. Therefore, it is not easy to improve environmental friendliness by realizing a chlorine-based resin-free binder while also improving adhesion to various substrates, lamination strength, and retort suitability in addition to basic ink properties such as dispersibility, fluidity, and printability.

JP 2005-298618 A

The present invention aims to provide an environmentally friendly liquid ink composition that does not contain chlorine-based resins and that has excellent adhesion to substrates, lamination strength, and retort resistance in addition to basic ink properties such as dispersibility, fluidity, and printability.

As a result of extensive research into solving the above-mentioned problems, the inventors have discovered that combining a specific polyurethane resin with a polyvinyl butyral resin (PVB) in a liquid ink composition is effective in solving the problems.

That is, the present invention relates to a liquid ink composition that contains a polyurethane resin (A) and a polyvinyl butyral resin (B), in which the polyurethane resin (A) is produced using polyester polyol (A-1) and polyether polyol (A-2) as reaction raw materials, and in which the mass ratio of polyester polyol (A-1) is high in the total mass of polyester polyol (A-1) and polyether polyol (A-2).

Furthermore, the present invention relates to a printed matter obtained by printing the liquid ink composition.

Furthermore, the present invention relates to a laminate having a printed layer formed by printing the liquid ink composition.

The present invention provides an environmentally friendly liquid ink composition that does not contain chlorine-based resins and that has excellent adhesion to substrates, lamination strength, and retort resistance in addition to basic ink properties such as dispersibility, fluidity, and printability.

The present invention will now be described in detail.
(Definition of words)
In the present invention, the liquid ink composition refers to a liquid printing 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 ink of the present invention does not contain an active energy curable component, i.e., it is an active energy ray non-reactive liquid ink.
In the following description, all "ink" refers to "printing ink." Furthermore, all "parts" refer to "parts by mass,""total amount of ink" refers to the total amount of ink including all volatile components such as organic solvents, and "total amount of ink solids" refers to the total amount of only non-volatile components, excluding volatile components.

The liquid ink composition of the present invention contains at least a polyurethane resin (A) and a polyvinyl butyral resin (B).

(Polyurethane resin (A))
The polyurethane resin (A) is made of polyester polyol (A-1) and polyether polyol (A-2) as reaction raw materials, and the mass ratio of polyester polyol (A-1) is large in the total mass of the polyester polyol (A-1) and polyether polyol (A-2). That is, in the polyol structure of the polyurethane resin (A), by adjusting the mass ratio of polyester polyol (A-1) so that polyester polyol (A-1) is more, boil resistance, retort resistance, and laminate strength can be improved. In addition, by containing polyether polyol (A-2), the dispersibility and fluidity of the ink can be improved, and the effect of improving adhesion can also be obtained.
Specifically, the mass ratio of the polyester polyol (A-1) to the polyether polyol (A-2) in the polyol structure is preferably in the range of 55:45 to 99:1, more preferably in the range of 60:40 to 98:2, and even more preferably in the range of 70:30 to 97:3.
When the mass ratio of the polyester polyol (A-1) and the polyether polyol (A-2) is within the range of 55:45 to 99:1, an ink having excellent lamination strength, adhesion and ink dispersibility can be obtained.

The polyester polyol (A-1) is preferably a polyester polyol obtained by dehydration condensation or polymerization of a low molecular weight polyol and a polycarboxylic acid or an anhydride thereof. The polyester polyol (A-1) can further increase the laminate strength by increasing the cohesive energy by introducing an ester group.

As the low molecular weight polyol, various known compounds having two or more hydroxyl groups that are generally used in the production of polyester polyols can be used, and one or more of them may be used in combination. Specifically, for example, glycols such as ethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol, 1,4-cyclohexanediol, and 1,4-cyclohexanedimethanol; 2-methyl-1,5-pentanediol, 3-methyl-1,5-pentanediol, 1,2-butanediol, 1,3-butanediol, 2-butyl-2-ethyl-1,3- Glycols with branched structures such as propanediol, 1,2-propanediol, 2-methyl-1,3-propanediol, neopentyl glycol, 2-isopropyl-1,4-butanediol, 2,4-dimethyl-1,5-pentanediol, 2,4-diethyl-1,5-pentanediol, 2-ethyl-1,3-hexanediol, 2-ethyl-1,6-hexanediol, 3,5-heptanediol, and 2-methyl-1,8-octanediol; glycerin, trimethylolpropane, trimethylolethane, pentaerythritol, and sorbitol can be used.

As the polycarboxylic acid or anhydride thereof, various known polycarboxylic acids generally used in the production of polyester polyols can be used, and one or more of them may be used in combination. Specifically, for example, polycarboxylic acids having 6 or less carbon atoms and two or more carboxyl groups, such as oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, fumaric acid, maleic acid, and anhydrides of these acids, aromatic dicarboxylic acids such as phthalic acid, isophthalic acid, terephthalic acid, and anhydrides of these acids, aliphatic dicarboxylic acids such as pimelic acid, suberic acid, azelaic acid, sebacic acid, and dimer acid, tricarboxylic acids such as trimellitic acid and anhydrides thereof, benzenetetracarboxylic acid, benzenepentacarboxylic acid, benzenehexacarboxylic acid, and anhydrides of these acids, etc. can be used.

The polyester polyol (A-1) may be any of various known polyester polyols commonly used in the production of polyurethane resins, such as polyester polyols obtained by ring-opening polymerization of lactones, such as cyclic ester compounds, for example, polycaprolactone, polyvalerolactone, poly(β-methyl-γ-valerolactone), etc., and one or more of these may be used in combination.

The number average molecular weight of the polyester polyol is preferably in the range of 500 to 8,000, more preferably in the range of 800 to 7,000, and even more preferably in the range of 900 to 6,000.
In the present invention, the number average and weight average molecular weights are values measured by gel permeation chromatography (GPC) under the following conditions.

Measurement device: High-speed GPC device ("HLC-8220GPC" manufactured by Tosoh Corporation)
Column: The following columns manufactured by Tosoh Corporation were used, connected in series.
"TSKgel G5000" (7.8mm I.D. x 30cm) x 1 "TSKgel G4000" (7.8mm I.D. x 30cm) x 1 "TSKgel G3000" (7.8mm I.D. x 30cm) x 1 "TSKgel G2000" (7.8mm I.D. x 30cm) x 1 Detector: RI (differential refractometer)
Column temperature: 40°C
Eluent: tetrahydrofuran (THF)
Flow rate: 1.0 mL/min Injection volume: 100 μL (sample concentration 0.4% by mass in tetrahydrofuran solution)
Standard sample: A calibration curve was prepared using the following standard polystyrene.

[Standard polystyrene]
"TSKgel Standard Polystyrene A-500" manufactured by Tosoh Corporation
"TSKgel Standard Polystyrene A-1000" manufactured by Tosoh Corporation
"TSKgel Standard Polystyrene A-2500" manufactured by Tosoh Corporation
"TSKgel Standard Polystyrene A-5000" manufactured by Tosoh Corporation
"TSKgel Standard Polystyrene F-1" manufactured by Tosoh Corporation
"TSKgel Standard Polystyrene F-2" manufactured by Tosoh Corporation
"TSKgel Standard Polystyrene F-4" manufactured by Tosoh Corporation
"TSKgel Standard Polystyrene F-10" manufactured by Tosoh Corporation
"TSKgel Standard Polystyrene F-20" manufactured by Tosoh Corporation
"TSKgel Standard Polystyrene F-40" manufactured by Tosoh Corporation
"TSKgel Standard Polystyrene F-80" manufactured by Tosoh Corporation
"TSKgel Standard Polystyrene F-128" manufactured by Tosoh Corporation
"TSKgel Standard Polystyrene F-288" manufactured by Tosoh Corporation
"TSKgel Standard Polystyrene F-550" manufactured by Tosoh Corporation

As the polyether polyol (A-2), various known polyether polyols generally used in the production of polyurethane resins can be used, and one or more of them may be used in combination. For example, polyether polyols of polymers or copolymers of methylene oxide, ethylene oxide, propylene oxide, tetrahydrofuran, etc. can be mentioned. Specifically, known general-purpose ones such as polyethylene glycol, polypropylene glycol, and polytetramethylene glycol may be used. By containing a polyether polyol, adhesion, particularly on a high-performance barrier film, is significantly improved, resulting in excellent blocking resistance and laminate strength.
The polyether polyol (A-2) preferably has a number average molecular weight of 100 to 3500. If the number average molecular weight of the polyether polyol is less than 100, the film of the polyurethane resin (A) tends to become hard, and the adhesion to the polyester film decreases. If the number average molecular weight is more than 3500, the film of the polyurethane resin tends to become brittle, and the blocking resistance of the ink film decreases.
The polyether polyol is preferably contained in the range of 1 to 40% by mass relative to the polyurethane resin. If the polyether polyol is less than 1 part by mass relative to 100 parts by mass of the polyurethane resin (A), the solubility of the polyurethane resin (A) in ketone, ester, and alcohol-based solvents decreases, and the adhesion to the high-performance barrier film tends to decrease. In addition, the resolubility of the ink film in the solvent decreases, and the tone reproducibility of the printed matter tends to decrease. If the amount exceeds 50 parts by mass, the ink film becomes excessively soft and tends to have poor blocking resistance.

In addition, as a polyol to be used in combination with the polyurethane resin (A) used in the liquid ink composition of the present invention as required, various known polyols generally used in the production of polyurethane resins can be used, and one or more of them may be used in combination. For example, saturated polyols such as 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, dipropylene glycol, glycerin, trimethylolpropane, trimethylolethane, 1,2,6-hexanetriol, 1,2,4-butanetriol, sorbitol, and pentaerythritol can be used. or unsaturated low molecular weight polyols (1); polycarbonate polyols (2) obtained by reacting the low molecular weight polyols with, for example, dimethyl carbonate, diphenyl carbonate, ethylene carbonate, phosgene, etc.; polybutadiene glycols (3); glycols (4) obtained by adding ethylene oxide or propylene oxide to bisphenol A; acrylic polyols (4) obtained by copolymerizing one or more hydroxyethyl groups, hydroxypropyl acrylate, hydroxybutyl acrylate, etc., or their corresponding methacrylic acid derivatives in one molecule with, for example, acrylic acid, methacrylic acid, or an ester thereof.

When the combined polyols described above include polyester polyols and/or polyether polyols, the content of the polyester polyols and/or polyether polyols contained in the combined polyols is also included in the polyester polyol and/or polyether polyol mass in the polyol structure of the polyurethane resin (A), respectively.

The diisocyanate compound used in the polyurethane resin (A) in the liquid ink composition of the present invention includes various known aromatic diisocyanates, aliphatic diisocyanates, alicyclic diisocyanates, etc. that are generally used in the production of polyurethane resins. For example, 1,5-naphthylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 4,4'-diphenyldimethylmethane diisocyanate, 4,4'-dibenzyl isocyanate, dialkyldiphenylmethane diisocyanate, tetraalkyldiphenylmethane diisocyanate, 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate, tolylene diisocyanate, butane-1,4-diisocyanate, hexamethylene diisocyanate, isopropylene diisocyanate, methylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, lysine diisocyanate, cyclohexane-1, ,4-diisocyanate, xylylene diisocyanate, isophorone diisocyanate, dimeryl diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, 1,3-bis(isocyanatemethyl)cyclohexane, methylcyclohexane diisocyanate, norbornane diisocyanate, m-tetramethylxylylene diisocyanate, 4,4-diphenylmethane diisocyanate, tolylene diisocyanate, bis-chloromethyl-diphenylmethane-diisocyanate, 2,6-diisocyanate-benzyl chloride, and dimer diisocyanate in which the carboxyl group of dimer acid is converted to an isocyanate group. These diisocyanate compounds can be used alone or in combination of two or more.

Examples of the chain extender used in the polyurethane resin (A) in the liquid ink composition of the present invention include ethylenediamine, propylenediamine, hexamethylenediamine, diethylenetriamine, triethylenetetramine, isophoronediamine, dicyclohexylmethane-4,4'-diamine, etc., as well as amines having a hydroxyl group in the molecule such as 2-hydroxyethylethylenediamine, 2-hydroxyethylpropyldiamine, 2-hydroxyethylpropylenediamine, di-2-hydroxyethylethylenediamine, di-2-hydroxyethylpropylenediamine, 2-hydroxypropylethylenediamine, di-2-hydroxypropylethylenediamine, di-2-hydroxypropylethylenediamine, etc. These chain extenders may 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 polyurethane resin (A) in the liquid ink composition of the present invention is produced, for example, by reacting polypropylene glycol and a polyol to be used with a diisocyanate compound in a ratio that results in an excess of isocyanate groups to obtain a prepolymer having terminal isocyanate groups, and then reacting the resulting prepolymer with a chain extender and/or a terminal blocking agent in a suitable solvent, i.e., an ester solvent such as ethyl acetate, propyl acetate, or butyl acetate that is commonly used as a solvent for non-toluene gravure inks; a ketone solvent such as acetone, methyl ethyl ketone, or methyl isobutyl ketone; an alcohol solvent such as methanol, ethanol, isopropyl alcohol, or n-butanol; a hydrocarbon solvent such as methylcyclohexane or ethylcyclohexane; or a mixture of these solvents, in a two-stage method, or by reacting polypropylene glycol and a polyol to be used with a diisocyanate compound, a chain extender, and/or a terminal blocking agent at once in a suitable solvent among the above. Of these methods, the two-stage method is preferable for obtaining a uniform polyurethane resin. In addition, when producing a polyurethane resin by a two-stage process, it is preferable to react the chain extender and/or the end blocking agent so that the total amino group (equivalent ratio) is 1/0.9 to 1.3. If the equivalent ratio of the isocyanate group to the amino group is less than 1/1.3, the chain extender and/or the end blocking agent may remain unreacted, causing the polyurethane resin to yellow or emitting an odor after printing.

The weight average molecular weight of the polyurethane resin (A) thus obtained is preferably within the range of 15,000 to 100,000, and more preferably within the range of 15,000 to 80,000. If the weight average molecular weight of the polyurethane resin is less than 15,000, the blocking resistance of the resulting ink composition and the strength and oil resistance of the printed film tend to be reduced, whereas if it exceeds 100,000, the viscosity of the resulting ink composition tends to be high and the gloss of the printed film tends to be reduced.
The content of the polyurethane resin (A) used in the liquid ink composition of the present invention in the ink (solid content of the polyurethane resin (A)) is preferably 4% by mass or more relative to the total mass of the ink from the viewpoint of sufficient adhesion of the ink to the printed material, and 25% by mass or less from the viewpoint of appropriate ink viscosity and work efficiency during ink production and printing, and more preferably in the range of 6 to 15% by mass. Furthermore, the lower limit of the solid content mass ratio in the ink is preferably 5% by mass, more preferably 10% by mass, more preferably 15% by mass, and even more preferably 20% by mass. Furthermore, the upper limit of the solid content weight ratio in the ink is preferably 95% by mass, more preferably 90% by mass, more preferably 80% by mass, and even more preferably 75% by mass.

(Polyvinyl butyral resin (B))
The liquid ink composition of the present invention can improve dispersibility by containing polyvinyl butyral resin (B). In addition, by using it in combination with urethane resin (A), adhesion, lamination strength, and retort resistance can be further improved. Since polyvinyl butyral resin (B) is composed of only carbon atoms, hydrogen atoms, and oxygen atoms, the risk of environmental pollution can be reduced during the life cycle of products such as packages using vinyl butyral resin (B).

The polyvinyl butyral resin (B) is not particularly limited and may be any known resin. In general, a reaction product obtained by acetalizing polyvinyl alcohol with butyraldehyde through a known reaction may be used.
The weight average molecular weight of the polyvinyl butyral resin (B) is preferably 5,000 to 60,000, more preferably 6,000 to 50,000, and even more preferably 7,000 to 40,000. By setting the weight average molecular weight of the polyvinyl butyral resin (B) within the above range, it is possible to obtain an ink having an excellent balance between fluidity and dispersibility.

The glass transition temperature (hereinafter sometimes referred to as Tg) of the polyvinyl butyral resin (B) is preferably in the range of 50°C to 120°C, more preferably in the range of 55°C to 115°C, and even more preferably in the range of 60°C to 110°C. In the present invention, the glass transition temperature is obtained by measurement using a differential scanning calorimeter.

The amount of hydroxyl groups in the polyvinyl butyral resin (B) is preferably in the range of 10 to 30% by mass, and more preferably 15 to 25% by mass. By setting the amount of hydroxyl groups in the polyvinyl butyral resin (B) in the above range, it is possible to obtain an ink having an excellent balance between fluidity and dispersibility.
The amount of acetyl groups in the polyvinyl butyral resin (B) is preferably 8% by mass to 10% by mass or less, and more preferably 5% by mass to 8% by mass. By setting the amount of acetyl groups in the polyvinyl butyral resin (B) within the above range, an ink having an excellent balance between fluidity and dispersibility can be obtained.

The content of polyvinyl butyral resin (B) (solid content of polyvinyl butyral resin (B)) is preferably 0.1 to 5 mass% relative to 100 mass% of the ink, more preferably 0.1 to 4.0 mass%, and most preferably 0.2 to 3.0 mass%. Adding a total of 0.1 mass% or more of polyvinyl butyral resin (B) tends to maintain the adhesion and transferability of the ink film, and setting the total to 5 mass% or less makes it possible to maintain the lamination strength and boil/retort resistance of the ink. In addition, the lower limit of the solid weight ratio in the ink is preferably 0.1 mass%, more preferably 0.2 mass%, and most preferably 0.3 mass%. In addition, the upper limit of the solid weight ratio in the ink is preferably 16 mass%, more preferably 13 mass%, and most preferably 10 mass%.
In order to obtain the effects of the present invention, the total mass of the polyurethane resin (A) and the polyvinyl butyral resin (B) is preferably 80 mass% or more, more preferably 85 mass% or more, even more preferably 90 mass% or more, and still more preferably 95 mass% or more, based on the total mass of the binder resin.

(Other binder resins)
The printing liquid ink of the present invention uses, as the binder resin, a polyurethane resin (A) and a polyvinyl butyral resin (B), and may contain a binder resin that can be used in combination in the technical field of liquid ink. The binder resin that can be used in combination is preferably a resin that does not contain a chlorine-based component from the viewpoint of reducing the environmental load, and examples of the binder resin that can be used in combination include ethylene-vinyl acetate copolymer resin, vinyl acetate resin, polyamide resin, acrylic resin, polyester resin, alkyd resin, rosin-based resin, rosin-modified maleic acid resin, ketone resin, cyclized rubber, petroleum resin, cellulose-based resin, and urethane resin other than polyurethane resin (A). Among these, it is preferable to contain a rosin-modified maleic acid resin, a cellulose-based resin, a polyester resin, or an acrylic resin.
The co-used resin may be used alone or in combination of two or more kinds. The content of the co-used resin is preferably 0.1 to 25% by mass, more preferably 2 to 15% by mass, based on the total mass of the ink.

(Cellulose-based resin)
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. The molecular weight is preferably 5,000 to 200,000, more preferably 10,000 to 50,000, in terms of weight average molecular weight. Also, the glass transition temperature is preferably 120°C to 180°C. When used in combination with the polyurethane resin (A) 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 (soluble cellulose) 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 groups to produce a nitric acid ester.

(Coloring Agent)
The colorant used in the liquid ink composition of the present invention may be either a colored pigment or a white pigment. If these pigments are not added, the composition can be used as an overcoat varnish.
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, chromophthalic yellow, chromophthalic 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 given 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 are C.I. Pigment Black 7 as a black pigment, 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 an indigo pigment, C.I. Pigment Green 7 as a green pigment, and 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. Examples of the pigments include 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, purple pigments include 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, etc., and it is preferable to use at least one or more selected from these groups.

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, 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 carbon black, aluminum particles, mica, bronze powder, chrome vermilion, yellow lead, cadmium yellow, cadmium red, ultramarine, Prussian blue, iron oxide red, yellow iron oxide, iron black, 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 ink composition, 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. In addition, the colorant can be used alone or in combination of two or more kinds.

The present invention may further contain additional resins, extender pigments, pigment dispersants, leveling agents, defoamers, waxes, plasticizers, infrared absorbers, ultraviolet absorbers, fragrances, flame retardants, etc., as necessary.

To stably disperse the pigment in an organic solvent, the resin alone can be used, but a dispersant can also be used in combination to further stably disperse the pigment. As the dispersant, anionic, nonionic, cationic, amphoteric, or other surfactants can be used. For example, comb-structured polymer compounds in which polyester is added to polyethyleneimine, or alkylamine derivatives of α-olefin maleic acid polymers can be used. Specific examples include the Solspers series (ZENECA), Ajisper series (Ajinomoto), and Homogenol series (Kao). In addition, the BYK series (BYK-Chemie), EFKA series (EFKA), and the like can also be used as appropriate. From the viewpoint of storage stability of the ink, the dispersant is preferably contained in the ink at 0.05% by mass or more of the total mass of the ink, and from the viewpoint of lamination suitability, it is more preferable that the dispersant is contained in the ink at 5% by mass or less of the total mass of the ink, and more preferably in the range of 0.1 to 2% by mass.

(Organic Solvent)
As the organic solvent used in the liquid ink composition of the present invention, various organic solvents can be used, for example, aromatic organic solvents such as toluene and xylene, ketone-based solvents such as acetone, methyl ethyl ketone and methyl isobutyl ketone, ester-based solvents such as ethyl acetate, n-propyl acetate, butyl acetate and propylene glycol monomethyl ether acetate, and alcohol-based solvents such as n-propanol, isopropanol, n-butanol and propylene glycol monomethyl ether, which can be used alone or in a mixture of two or more. In recent years, from the viewpoint of the working environment, it is more preferable not to use aromatic solvents such as toluene and xylene or ketone-based solvents.

The liquid ink composition of the present invention may contain water as a volatile component together with the organic solvent. The content of water is preferably less than 10% by mass of the total ink composition. The addition of water makes it possible to control the drying property of the ink, and in particular in gravure printing, the gradation part characterized by a small amount of ink transfer can be beautifully reproduced. Furthermore, it is particularly preferable that the content of water is in the range of 1 to 5% by mass of the total ink composition, since this improves the printability.
In addition, the addition of water can reduce the amount of organic solvent used. Water may be added to the organic solvent in advance to form a water-containing organic solvent, or a specific amount of water may be added separately.
The liquid ink composition of the present invention can be a one-component type that does not use a curing agent such as an isocyanate curing agent, or a two-component type that uses a curing agent, and can provide a liquid ink composition with excellent ink dispersibility and flowability.

The liquid ink composition of the present invention can be produced by dissolving and/or dispersing a resin, a pigment, etc. in an organic solvent. Specifically, a pigment dispersion is produced by dispersing a pigment in an organic solvent using a polyurethane resin, and the resulting pigment dispersion can be mixed with other compounds, etc., as necessary, to produce an 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, such as polyurethane resin, colorant, organic solvent, etc. The viscosity of the ink can also be adjusted by adjusting the particle size and particle size distribution of the pigment in the ink.

The hues of the liquid ink composition of the present invention are five basic process colors, yellow, red, indigo, black, and white, depending on the type of pigment used, and three outside the process gamut colors, red (orange), grass (green), and purple. In addition, transparent yellow, peony, vermilion, brown, gold, silver, pearl, and a nearly transparent medium (containing an extender pigment as necessary) for adjusting color density are prepared as base colors. Inks for boil retort printing are appropriately selected taking into consideration the migration properties and heat resistance of the pigment. The base inks of each hue are diluted with a diluting solvent to a viscosity and concentration suitable for gravure printing or flexographic printing, and are supplied to each printing unit alone or mixed together.

The printed matter obtained by printing the liquid ink composition of the present invention is useful for a wide variety of films, from general-purpose films to various high-performance films. The plastic films that can be used are not particularly limited, and include, for example, polyamide resins such as Ny6, nylon 66, and nylon 46, polyester resins such as polyethylene phthalate (PET), polyethylene naphthalate, polytrimethylene terephthalate, polytrimethylene naphthalate, polybutylene terephthalate, and polybutylene naphthalate, polyhydroxycarboxylic acids such as polylactic acid, biodegradable resins such as aliphatic polyester resins such as poly(ethylene succinate) and poly(butylene succinate), polyolefin resins such as polypropylene (PP), polyethylene, polyimide resins, polyarylate resins, and thermoplastic resins such as mixtures thereof, various high-performance films with inorganic or organic barrier coating materials applied to the surface, and laminates thereof, among which, films made of polyester, polyamide, polyethylene, and polypropylene can be preferably used.
These films may be unstretched or stretched films, and there is no limitation on the manufacturing method. The thickness of the base film is also not particularly limited, but is usually in the range of 1 to 500 μm.
It is also preferable that the printed surface of the film is subjected to a corona discharge treatment, since this can further improve the adhesion to the substrate. Silica, alumina, etc. may also be vapor-deposited on the printed surface.
The printing method can be a printing method using a known plate such as gravure printing or flexographic printing, but gravure printing is particularly preferred. The cylinder used in gravure printing is a known type such as an engraved type or an etching type. The liquid ink composition of the present invention is also useful as a laminate having a printed layer printed thereon.

The present invention will be described more specifically with reference to examples. In the following, "parts" and "%" are all based on mass.
In the present invention, the weight average molecular weight (converted into polystyrene) was measured by gel permeation chromatography (GPC) using an HLC8220 system manufactured by Tosoh Corporation under the following conditions.
Separation column: Four columns of TSKgel GMHHR-N manufactured by Tosoh Corporation were used. Column temperature: 40° C. Mobile phase: Tetrahydrofuran manufactured by Wako Pure Chemical Industries, Ltd. Flow rate: 1.0 ml/min. Sample concentration: 1.0 wt %. Sample injection amount: 100 microliters. Detector: differential refractometer.
The viscosity was measured at 25° C. using a Tokimec B-type viscometer.

(Synthesis Example 1: Polyurethane resin solution P1)
A four-neck flask equipped with a stirrer, a thermometer, a reflux condenser and a nitrogen gas inlet tube was charged with 233.38 parts of neopentyl glycol adipate diol (hydroxyl value: 37.4 mg KOH / g), 190.95 parts of polyethylene glycol (hydroxyl value: 112.2 mg KOH / g) and 89.49 parts of isophorone diisocyanate, and reacted for 10 hours at 90 ° C. under a nitrogen stream to produce a urethane prepolymer with an isocyanate group content of 2.09 mass%, and then 128.15 parts of ethyl acetate were added to the mixture to obtain a uniform solution of the urethane prepolymer. Next, the urethane prepolymer solution was added to a mixture consisting of 23.87 parts of isophorone diamine, 0.30 parts of cyclohexylamine, 750.3 parts of ethyl acetate and 376.6 parts of isopropyl alcohol, and the mixture was stirred and reacted at 45 ° C. for 5 hours to obtain a polyurethane resin solution P1. The resulting polyurethane resin solution P1 had a resin solids concentration of 30.3% by mass, and the Mw of the resin solids was 54,000.

(Synthesis Example 2: Polyurethane resin solution P2)
A four-neck flask equipped with a stirrer, a thermometer, a reflux condenser and a nitrogen gas inlet tube was charged with 233.38 parts of neopentyl glycol adipate diol (hydroxyl value: 37.4 mg KOH / g), 2.36 parts of polyethylene glycol (hydroxyl value: 280.5 mg KOH / g) and 31.58 parts of isophorone diisocyanate, and reacted for 10 hours at 90 ° C. under a nitrogen stream to produce a urethane prepolymer with an isocyanate group content of 1.77% by mass, and then 66.8 parts of ethyl acetate was added to this to obtain a uniform solution of the urethane prepolymer. Next, the urethane prepolymer solution was added to a mixture consisting of 10.59 parts of isophorone diamine, 0.28 parts of cyclohexylamine, 387.6 parts of ethyl acetate and 194.7 parts of isopropyl alcohol, and the mixture was stirred and reacted at 45 ° C. for 5 hours to obtain a polyurethane resin solution P2. The resulting polyurethane resin solution P2 had a resin solids concentration of 30.3% by mass, and the Mw of the resin solids was 58,000.

(Synthesis Example 3: Polyurethane resin solution P3)
A four-neck flask equipped with a stirrer, a thermometer, a reflux condenser and a nitrogen gas inlet tube was charged with 233.38 parts of neopentyl glycol adipate diol (hydroxyl value: 37.4 mg KOH / g), 7.22 parts of polyethylene glycol (hydroxyl value: 280.5 mg KOH / g) and 60.19 parts of isophorone diisocyanate, and reacted for 10 hours at 90 ° C. under a nitrogen stream to produce a urethane prepolymer with an isocyanate group content of 4.80 mass%, and then 75.2 parts of ethyl acetate were added to this to obtain a uniform solution of the urethane prepolymer. Next, the urethane prepolymer solution was added to a mixture consisting of 30.40 parts of isophorone diamine, 0.28 parts of cyclohexylamine, 466.2 parts of ethyl acetate and 232.0 parts of isopropyl alcohol, and the mixture was stirred and reacted at 45 ° C. for 5 hours to obtain a polyurethane resin solution P3. The resulting polyurethane resin solution P3 had a resin solids concentration of 30.4% by mass, and the Mw of the resin solids was 62,000.

(Synthesis Example 4: Polyurethane resin solution P4)
A four-neck flask equipped with a stirrer, a thermometer, a reflux condenser and a nitrogen gas inlet tube was charged with 233.38 parts of neopentyl glycol adipate diol (hydroxyl value: 37.4 mg KOH / g), 41.18 parts of polyethylene glycol (hydroxyl value: 280.5 mg KOH / g) and 60.19 parts of isophorone diisocyanate, and reacted for 10 hours at 90 ° C. under a nitrogen stream to produce a urethane prepolymer with an isocyanate group content of 2.17% by mass, and then 83.7 parts of ethyl acetate were added to the mixture to obtain a uniform solution of the urethane prepolymer. Next, the urethane prepolymer solution was added to a mixture consisting of 15.99 parts of isophorone diamine, 0.32 parts of cyclohexylamine, 489.7 parts of ethyl acetate and 245.7 parts of isopropyl alcohol, and the mixture was stirred and reacted at 45 ° C. for 5 hours to obtain a polyurethane resin solution P4. The resulting polyurethane resin solution P4 had a resin solids concentration of 30.3% by mass, and the Mw of the resin solids was 60,000.

(Comparative Synthesis Example 1: Polyurethane Resin Solution P5)
A four-neck flask equipped with a stirrer, a thermometer, a reflux condenser and a nitrogen gas inlet tube was charged with 240.65 parts of polyethylene glycol (hydroxyl value: 56.1 mgKOH/g) and 40.07 parts of isophorone diisocyanate, and reacted for 10 hours at 90 ° C. under a nitrogen stream to produce a urethane prepolymer with an isocyanate group content of 1.72% by mass, and then 70.2 parts of ethyl acetate was added to the mixture to obtain a uniform solution of the urethane prepolymer. Next, the urethane prepolymer solution was added to a mixture consisting of 10.65 parts of isophorone diamine, 0.22 parts of cyclohexylamine, 406.1 parts of ethyl acetate and 204.1 parts of isopropyl alcohol, and the mixture was stirred and reacted at 45 ° C. for 5 hours to obtain a polyurethane resin solution P5. The obtained polyurethane resin solution P5 had a resin solid concentration of 30.2% by mass and a resin solid Mw of 65,000.

(Comparative Synthesis Example 2: Polyurethane Resin Solution P6)
A four-neck flask equipped with a stirrer, a thermometer, a reflux condenser and a nitrogen gas inlet tube was charged with 240.65 parts of neopentyl glycol adipate diol (hydroxyl value: 36.1 mgKOH/g) and 40.07 parts of isophorone diisocyanate, and reacted under a nitrogen stream at 90°C for 10 hours to produce a urethane prepolymer with an isocyanate group content of 1.72% by mass, and then 70.2 parts of ethyl acetate was added to the mixture to obtain a uniform solution of the urethane prepolymer. Next, the urethane prepolymer solution was added to a mixture consisting of 10.87 parts of isophorone diamine, 0.22 parts of cyclohexylamine, 406.4 parts of ethyl acetate and 204.3 parts of isopropyl alcohol, and the mixture was stirred and reacted at 45°C for 5 hours to obtain a polyurethane resin solution P6. The obtained polyurethane resin solution P6 had a resin solids concentration of 30.1% by mass and a resin solids Mw of 58,000.

(Comparative Synthesis Example 3: Polyurethane resin solution P7)
A four-neck flask equipped with a stirrer, a thermometer, a reflux condenser and a nitrogen gas inlet tube was charged with 120.3 parts of neopentyl glycol adipate diol (hydroxyl value: 56.1 mg KOH / g), 120.3 parts of polyethylene glycol (hydroxyl value: 112.2 mg KOH / g) and 60.09 parts of isophorone diisocyanate, and reacted for 10 hours at 90 ° C. under a nitrogen stream to produce a urethane prepolymer with an isocyanate group content of 2.41 mass%, and then 75.2 parts of ethyl acetate were added to the mixture to obtain a uniform solution of the urethane prepolymer. Next, the urethane prepolymer solution was added to a mixture consisting of 15.73 parts of isophorone diamine, 0.29 parts of cyclohexylamine, 442.1 parts of ethyl acetate and 221.7 parts of isopropyl alcohol, and the mixture was stirred and reacted at 45 ° C. for 5 hours to obtain a polyurethane resin solution P7. The resulting polyurethane resin solution P7 had a resin solids concentration of 30.5% by mass, and the Mw of the resin solids was 62,000.

(Preparation of polyvinyl butyral resin solution B1)
A polyvinyl butyral resin (weight average molecular weight 10,000, hydroxyl group content 15 mass%, glass transition point 60°C, acetyl group content 8 mass%) obtained by reacting polyvinyl alcohol with butylaldehyde was made into a 10% solution in isopropyl alcohol, and this was named polyvinyl butyral resin solution B1.

(Preparation of polyvinyl butyral resin solution B2)
A polyvinyl butyral resin (weight average molecular weight 20,000, hydroxyl group content 20 mass%, glass transition point 70°C, acetyl group content 4 mass%) obtained by reacting polyvinyl alcohol with butylaldehyde was made into a 10% solution in isopropyl alcohol, and this was named polyvinyl butyral resin B2.

(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 having a resin solid content concentration of 20% by mass.

(Preparation of Maleic Acid Resin Solution M)
A maleic acid resin solution M was prepared by mixing "SMA 3000P" manufactured by Tomoe Engineering Co., Ltd. in a mixture of 25% IPA, 25% ethyl acetate, and 50% SMA 3000P to prepare a 50% solids solution, which was then thoroughly stirred.

(Preparation of vinyl chloride/vinyl acetate copolymer resin solution)
A hydroxyl group-containing vinyl chloride-vinyl acetate copolymer resin (resin monomer composition by weight: vinyl chloride/vinyl acetate/vinyl alcohol=92/3/5, hydroxyl value (mg KOH)=64) was made into a 10% solution in ethyl acetate, and this was designated as vinyl chloride-vinyl acetate resin solution V.

Example 1
A mixture of 30 parts of polyurethane resin solution P1 (solid content 30%), 25 parts of polyvinyl butyral resin B1 (solid content 10%), 1 part of maleic acid resin solution M (solid content 50%), 3 parts of cellulose acetate propionate resin solution Ca (solid content 20%), 10 parts of a phthalocyanine blue pigment (FASTGEN Blue LA5380: manufactured by DIC Corporation), and 31 parts of ethyl acetate, totaling 100 parts, was kneaded using a Dynomill (manufactured by Willy & Bachofenon) to prepare a liquid ink of the present invention.

(Examples 2 to 10 and Comparative Examples 1 to 7)
For Examples 2 to 10 and Comparative Examples 1 to 7, liquid inks were produced using the formulations shown in Tables 1 to 3 in the same manner as in Example 1.

The resulting liquid ink was evaluated using the following test methods.

(Color-based fluidity)
The viscosity of the inks described in the Examples and Comparative Examples was measured using a Brookfield viscometer at revolutions of 6 rpm and 60 rpm. The TI value was calculated by dividing the viscosity measured at 6 rpm by the viscosity measured at 60 rpm. If the TI value is less than 3.0, the ink is usable for practical use.
○: TI value is less than 1.5 △: TI value is 1.5 or more but less than 3.0 ×: TI value is 3.0 or more

(viscosity)
The viscosity of the inks described in the Examples and Comparative Examples was measured using a Zahn cup #4 (manufactured by Rigo Co., Ltd.). If the viscosity was 30 seconds or less, the inks were usable for practical use.

(Storage stability)
The inks described in the Examples and Comparative Examples were allowed to stand at 25° C. for one week, and then the degree of separation and precipitation was evaluated.
<Separation> Appearance evaluation: ◯: No separation observed at all.
△: Some separation is observed in the upper layer. As a guideline, the thickness of the separated layer is 5 mm or less.
×: Clear separation is observed in the upper layer. As a guideline, the thickness of the separated layer is 5 mm or more.
<Sedimentation> Gently scrape the bottom of the container storing the ink with a spatula.
A: No precipitation is observed.
△: A small amount of sediment is seen at the bottom. (A small amount of sediment is seen at the tip of the spatula.)
×: A lot of sediment is found at the bottom. (Much of the sediment can be scraped off with a spatula.)

(Hue)
The inks described in the Examples and Comparative Examples were applied to a PET film using a bar coater #4 (RDS Co., Ltd.), and the hue was visually evaluated. The PET film used was E5100 (12 μm) manufactured by Toyobo Co., Ltd., and the standard ink was Finart R507 primary blue (DIC Co., Ltd.).
◯: Has the same hue as the standard ink.
△: The hue is slightly inferior to the standard ink.
×: The hue is significantly inferior to the standard ink.

(Adhesion)
The viscosity of the inks described in the Examples and Comparative Examples was adjusted with ethyl acetate to 16 seconds (25°C) using a Zahn cup #3 (manufactured by Rigo Co., Ltd.), and printed matter made from various films, including OPP, PET, NY, and transparent vapor deposition film, was left for one day using a gravure proofing machine equipped with a gravure plate with a plate depth of 35 μm. After leaving cellophane tape (manufactured by Nichiban, 12 mm width) on the printed surface, the tape was quickly peeled off and the appearance of the printed film was visually judged on the following three-point scale.
The OPP film was P2161 (20 μm) manufactured by Toyobo Co., Ltd., the PET film was E5100 (12 μm) manufactured by Toyobo Co., Ltd., the NY film was ON-RT (15 μm) manufactured by Unitika Ltd., and the transparent vapor deposition film was alumina vapor-deposited transparent PET film IB-PET-PUB (12 μm) manufactured by Dai Nippon Printing Co., Ltd.
A: The printed film did not peel off at all.
Δ: 50-80% of the printed film remained on the film.
x: 50% or less of the printed film remained on the film.

(Boiling resistance)
As in the above evaluation of adhesion, a print was made on the treated surface of a Ny film that had been corona-treated on one side. A linear low-density polyethylene film (LLDPE film: Mitsui Chemicals Tohcello Co., Ltd. TUX-HC, thickness 60 μm) was laminated on the printed Ny film using a urethane-based dry laminating adhesive DIC Dry LX-500/KW-75 (DIC) by a dry laminating machine (DIC Engineering), and aged at 40° C. for 3 days to obtain a laminate. The obtained laminate was made into a pouch with a size of 120 mm x 120 mm, and 70 g of a pseudo food containing vinegar, salad oil, and meat sauce in a weight ratio of 1:1:1 was filled and sealed. The prepared pouch was boiled at 98° C. for 60 minutes, the contents were removed, and the pouch was washed with water. The bag was then cut into a width of 15 mm and subjected to a T-peel test at a pulling speed of 300 mm/min.
The laminate produced was composed of Ny substrate (F)/printing ink layer (I) from the Ny film side of the substrate.
)/adhesive layer (Ad)/LLDPE film. The higher the value, the higher the strength.
The abbreviations for the evaluation results in the table are as follows.
F Cut: Abbreviation for FILM CUT, which indicates that the film breaks before the laminate peels off during measurement. The greater the laminate strength is than the film strength, the higher and more excellent it is.
I/AL: Peeling occurred at the adhesive layer (Ad1) between the printed ink layer (I) and the aluminum foil (AL) at the measured value shown.
F/I: Peeling occurred between the PET substrate (F) and the printed ink layer (I) at the measured value shown.
In addition, the appearance of the resulting pouch after boiling treatment was evaluated.
Good: No delamination or blistering observed.
△: Slight delamination or blistering is observed in some parts of the pouch.
×: Clear delamination or blisters are observed throughout the pouch.

(Retort resistance)
As in the above evaluation of adhesion, printing was performed on the treated surface of a PET film that had been corona-treated on one side. Aluminum foil and a non-oriented polypropylene film (hereinafter, R-CPP: ZK-75 50 μm, manufactured by Toray Synthetic Films Co., Ltd.) were laminated on the printed matter of the biaxially oriented polyester film using a urethane-based dry laminating adhesive DIC Dry LX-703VL/KR-90 (manufactured by DIC Engineering) with a dry laminating machine, and aging was performed at 40 ° C. for 3 days to obtain a laminate. The obtained laminate was made into a pouch of 120 mm × 120 mm in size, and 70 g of a pseudo food containing vinegar, salad oil, and meat sauce in a weight ratio of 1:1:1 was filled and sealed as the contents. The prepared pouch was subjected to steam retort sterilization at 135° C. for 30 minutes, the contents were removed, and the pouch was washed with water. The bag was then cut into a width of 15 mm and subjected to a T-peel test at a pulling speed of 300 mm/min.
The laminate thus prepared was composed of a PET substrate (F)/printing ink layer (I) from the PET film side of the substrate.
)/adhesive layer (Ad1)/aluminum foil (AL)/adhesive (Ad2)/R-CPP film. A biaxially oriented polyester film (PET film: E-5100, 12 μm thick, manufactured by Toyobo Co., Ltd.) was used. The higher the value, the higher the strength.
The abbreviations for the evaluation results in the table are as follows.
F Cut: Abbreviation for FILM CUT, which indicates that the film breaks before the laminate peels off during measurement. The greater the laminate strength is than the film strength, the higher and more excellent it is.
I/AL: Peeling occurred at the adhesive layer (Ad1) between the printing ink layer (I) and the aluminum foil (AL) at the measured value shown.
F/I: Peeling occurred between the PET substrate (F) and the printed ink layer (I) at the measured value shown.
In addition, the appearance of the resulting pouch after retort treatment was evaluated.
Good: No delamination or blistering observed.
△: Slight delamination or blistering is observed in some parts of the pouch.
×: Clear delamination or blisters are observed throughout the pouch.

The results are shown in the table below. Note that the viscosity, hue, and storage stability of Comparative Examples 4 and 5 were outside the practical range, and the tape adhesion, boil resistance, and retort resistance could not be evaluated.

FASTGEN Blue LA5380:B15:3
SYMULER RED 4580:R146
SYMULER FAST RED 4136F:R213
SYMULER FAST YELLOW 4619:Y83
FASTOGEN SUPER VIOLET RSP:V23

As can be seen from the table, Examples 1 to 15 achieved excellent results in all evaluations of fluidity, storage stability, adhesion, boiling resistance and retort resistance, and it was found that inks with an excellent balance of various performance properties could be obtained without using chlorine-based resins.
On the other hand, Comparative Examples 1 to 3 using polyurethane resins P5 to P7 resulted in inferior laminate strength and dispersibility. Comparative Examples 1 and 2 and Comparative Examples 6 and 7 show that the laminate strength and dispersibility are significantly decreased when polyurethane resins P5 to P7 are combined with polyvinyl butyral resin, but the Examples show that excellent effects can be obtained by combining specific polyurethane resins (P1 to P4) with polyvinyl butyral resin.

Claims (11)

The composition contains a polyurethane resin (A), a polyvinyl butyral resin (B), and an organic solvent (E),
the polyurethane resin (A) is produced using polyester polyol (A-1) and polyether polyol (A-2) as reaction raw materials, the mass ratio of the polyester polyol (A-1) is large in the total mass of the polyester polyol (A-1) and the polyether polyol (A-2),
Does not contain vinyl chloride copolymer resin.
A liquid ink composition, wherein the organic solvent does not contain a ketone solvent.
However, the polyurethane resin (A) does not include those using a hydroxyldialkylamine compound having one hydroxyl group in the molecule as a reaction raw material.
The polyurethane resin (A) does not include a polyurethane resin having an acid value of 15 to 70 mgKOH/g and a hydroxyl value of 1 to 35 mgKOH/g. The liquid ink composition according to claim 1, wherein the polyether polyol (A-2) is polyethylene glycol and/or polypropylene glycol. The liquid ink composition according to claim 1 or 2, wherein the polyester polyol (A-1) has a number average molecular weight of 500 to 8000. The liquid ink composition according to any one of claims 1 to 3, wherein the polyether polyol (A-2) has a number average molecular weight of 100 to 3,500. The liquid ink composition according to any one of claims 1 to 4, wherein the mass ratio of the polyester polyol (A-1) and the polyether polyol (A-2) is in the range of 55:45 to 99:1. The liquid ink composition according to any one of claims 1 to 5, wherein the polyvinyl butyral resin (B) has a number average molecular weight of 5,000 to 60,000, a glass transition point of 50 to 120°C, and a hydroxyl group content of 10 to 30% by mass. The liquid ink composition according to any one of claims 1 to 6, containing 0.1 to 5.0% by mass of the polyvinyl butyral resin (B) relative to 100% by mass of the liquid ink composition. The liquid ink composition according to any one of claims 1 to 7 further contains at least one resin selected from maleic acid resin, cellulose resin, polyester resin, acrylic resin, and polyamide resin. The liquid ink composition according to any one of claims 1 to 8 further contains a colorant (D). A printed matter obtained by printing the liquid ink composition according to any one of claims 1 to 9 . A laminate having a printed layer formed by printing the liquid ink composition according to any one of claims 1 to 9 .