JP2019006909A - Liquid ink composition - Google Patents

Abstract

To provide a liquid ink composition that has excellent viscosity stability in both one-liquid type that does not use a curing agent and a two-liquid type that uses a curing agent, while maintaining basic performances such as blur test, plate fogging test, printability such as density stability, laminate strength, retort resistance, in gravure printing or flexographic printing.SOLUTION: A liquid ink composition contains a binder resin (A), an organic solvent (B), and a hydroxy carboxylic acid (C).SELECTED DRAWING: None

Description

  The present invention relates to both a one-component liquid ink composition that does not use a curing agent and a two-component liquid ink composition that uses a curing agent in gravure printing or flexographic printing.

The liquid ink for laminating mainly used for the production of soft packaging materials mainly uses urethane resin or urethane urea resin as a main component as a resin binder. Further, in recent years, the use of aromatic solvents such as toluene and ketone solvents such as methyl ethyl ketone is being restricted in view of both work hygiene during printing and the harmfulness of packaging materials. From the viewpoint of printability, this toluene-free liquid ink is aromatic as a solvent, instead of a ketone solvent, an acetic acid ester such as ethyl acetate or propyl acetate, an alcohol solvent such as isopropyl alcohol or normal propyl alcohol, or These mixed solvents tend to be used.
However, even liquid inks that do not use such aromatic solvents and ketone solvents cannot avoid the release of volatile organic chemicals (VOC) into the atmosphere. Therefore, it is useful to use water together with an organic solvent in order to reduce the VOC emission amount, and the combined use of water is also useful for improving the transferability of the ink. Add isocyanate curing agent to improve physical properties (
There are two liquid types), but the viscosity stability tends to be inferior. Especially when water enters, it tends to get worse.

For example, a binder for printing ink is disclosed that contains styrene maleic anhydride as a stabilizer in a polyurethane resin solution and is excellent in stability over time (for example, see Patent Document 1). However, when styrene-maleic anhydride is added, the viscosity stability is good in the two-component type in which the curing agent is added, but in the case of the one-component type in which the curing agent is not added, the viscosity stability is not sufficient. . It is desired that the viscosity stability is sufficiently good in both cases of the one-component type and the two-component type.
Further, Patent Document 2 discloses a gravure ink containing a glycol ether organic solvent and water, but this cannot be said to have sufficient viscosity stability particularly when two liquids are used.

JP, 2014-005318, A Japanese Patent No. 6090521

  The subject of the present invention is that gravure printing or flexographic printing does not use a curing agent while maintaining basic performance such as printability such as crease test, plate fog test, density stability, laminate strength, and retort resistance. An object of the present invention is to provide a liquid ink composition which is excellent in viscosity stability in both the one-component type and the two-component type using a curing agent. Another object of the present invention is to provide a printed material obtained by printing the liquid ink composition, and a laminate having a printed layer obtained by printing the liquid ink composition.

  In the present invention, by adding a viscosity stabilizer to a binder resin and an organic solvent, in gravure printing or flexographic printing, printability such as a blurring test, plate fogging test, density stability, laminate strength, retort resistance, etc. The present invention has been completed by providing a liquid ink composition that is excellent in viscosity stability in both a one-component type that does not use a curing agent and a two-component type that uses a curing agent while maintaining the basic performance of the present invention. .

  That is, the present invention firstly relates to a liquid ink composition comprising a binder resin (A), an organic solvent (B), and a hydroxycarboxylic acid (C).

  The present invention also relates to a liquid ink composition in which the binder resin (A) is a polyurethane resin and / or a polyurethane polyurea resin.

  The present invention also relates to a liquid ink composition containing less than 10% by weight of water in the liquid ink composition.

  The present invention also relates to a liquid ink composition in which the binder resin (A) further contains a vinyl chloride-vinyl acetate copolymer resin.

  The present invention further relates to a liquid ink composition containing a colorant (D).

  The present invention also relates to a liquid ink composition in which the polyurethane resin and / or polyurethane urea resin has an amino group.

  The present invention also relates to a liquid ink composition having an amine value in terms of solid content of the polyurethane resin and / or polyurethane urea resin of 10.0 mgKOH / g or less.

  The present invention also relates to a liquid ink composition in which the organic solvent (B) does not contain an aromatic organic solvent and / or a ketone solvent.

  Moreover, this invention relates to the printed matter formed by printing this liquid ink composition.

  Moreover, this invention relates to the laminated body which has a printing layer formed by printing this liquid ink composition.

  According to the present invention, in gravure printing or flexographic printing, one liquid which does not use a curing agent while maintaining basic properties such as printability such as a blurring test, plate fogging test, density stability, laminate strength, and retort resistance. A liquid ink composition excellent in viscosity stability can be obtained in both the type and the two-component type using a curing agent.

  The present invention provides a liquid ink composition comprising a binder resin (A), an organic solvent (B), and a hydroxycarboxylic acid (C).

Examples of the binder resin (A) used in combination with the liquid ink composition of the present invention as necessary include, for example, the polyurethane resin, polyurethane urea resin, chlorinated polypropylene resin, ethylene-vinyl acetate copolymer resin, vinyl acetate. Examples thereof include resins, polyamide resins, acrylic resins, polyester resins, alkyd resins, polyvinyl chloride resins, rosin resins, rosin-modified maleic acid resins, ketone resins, cyclized rubbers, chlorinated rubbers, butyral, and petroleum resins. The combined resins can be used alone or in admixture of two or more. Content of combined use resin is the range of 1-50 mass% in conversion of solid content with respect to the total mass of an ink composition, More preferably, it is 2-40 mass%. Of these, polyurethane resins and polyurethane polyurea resins are preferred, and each may be used alone or in combination of two.
The content of the polyurethane resin and / or polyurethane polyurea resin in the liquid ink composition of the present invention is, for example, in the case of gravure printing, with respect to the total mass of the ink from the viewpoint of sufficient adhesion of the gravure ink to the printing medium. In terms of solid content, it is preferably 5% by mass or more, and preferably 25% by mass or less from the viewpoint of moderate ink viscosity and work efficiency during ink production and printing. In the case of flexographic printing, the solid content is based on the total mass of flexo ink. It is preferably 5% by mass or more and 30% by mass or less in terms of conversion.

  The number average molecular weight of the polyurethane resin and the polyurethane polyurea resin used in the liquid ink composition of the present invention is preferably in the range of 15,000 to 100,000. When the number average molecular weight of the polyurethane resin or polyurethane polyurea resin is less than 15,000, the resulting ink tends to have low blocking resistance, laminate strength, chemical resistance and the like. , The viscosity of the obtained ink is increased, and a predetermined printing density tends to be not obtained.

  The polyurethane resin and / or polyurethane urea resin used in the liquid ink composition of the present invention preferably uses polyester polyol and / or polyether polyol as a reaction raw material. The number average molecular weight of the polyester polyol is preferably 3000 to 7000.

  When the number average molecular weight of the polyester polyol is less than 3000, the film of the polyurethane resin and / or polyurethane urea resin tends to be hard, and the adhesion to the polyester film tends to be lowered. When the number average molecular weight is larger than 7000, the polyurethane resin film tends to be brittle, and the blocking resistance of the ink film tends to be lowered. On the other hand, the polyether polyol is preferably 1 to 50 parts by mass with respect to 100 parts by mass of the polyurethane resin, and if the polyether polyol is less than 1 part by mass, the polyurethane resin is added to the ketone, ester or alcohol solvent. In addition to the decrease in solubility, the adhesion particularly on the high-functional barrier film tends to decrease. Further, the re-solubility of the ink film in the solvent is lowered, and the tone reproducibility of the printed matter tends to be lowered. On the other hand, if it exceeds 50 parts by mass, the ink film tends to be excessively soft and the anti-blocking tendency tends to be poor.

  In addition, the number average molecular weight of the said polyester polyol shows the value measured on condition of the following by gel permeation chromatography (GPC) method.

Measuring device: High-speed GPC device (“HLC-8220GPC” manufactured by Tosoh Corporation)
Column: The following columns manufactured by Tosoh Corporation were connected in series.
"TSKgel G5000" (7.8 mm ID x 30 cm) x 1 "TSKgel G4000" (7.8 mm ID x 30 cm) x 1 "TSKgel G3000" (7.8 mm ID x 30 cm) x 1 “TSKgel G2000” (7.8 mm ID × 30 cm) × 1 detector: RI (differential refractometer)
Column temperature: 40 ° C
Eluent: Tetrahydrofuran (THF)
Flow rate: 1.0 mL / min Injection amount: 100 μL (tetrahydrofuran solution with a sample concentration of 0.4 mass%)
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 said polyester polyol, what is obtained by a well-known esterification reaction with the compound and polybasic acid which have 2 or more of hydroxyl groups can be used, for example.
The compound having two or more hydroxyl groups is used as a chain extender. For example, ethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6 -Glycols such as hexanediol, diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol; 2-methyl-1,5-pentanediol 3-methyl-1,5-pentanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2-butyl-2-ethyl-1,3-propanediol, 1, 2-propanediol, 2-methyl-1,3- Lopandiol, neopentyl glycol, 2-isopropyl-1,4-butanediol, 2,4-dimethyl-1,5-pentanediol 2,4-diethyl-1,5-pentanediol, 2-ethyl-1,3- Glycols having a branched structure such as hexanediol, 2-ethyl-1,6-hexanediol, 3,5-heptanediol, 2-methyl-1,8-octanediol; trimethylolpropane, trimethylolethane, pentaerythritol, Aliphatic polyols such as saccharose, methylene glycol, glycerin, sorbitol; bisphenol A, 4,4′-dihydroxydiphenyl, 4,4′-dihydroxydiphenyl ether, 4,4′-dihydroxydiphenyl sulfone, hydrogenated bisphenol A, hydroquinone, etc. Good The number average molecular weight of such families polyol compounds can be used in the range of 50 to 400. These chain extenders may be used alone or in combination of two or more.
Examples of the polybasic acid include succinic acid, adipic acid, azelaic acid, sebacic acid, dodecanedicarboxylic acid, maleic anhydride, fumaric acid, 1,3-cyclopentanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, phthalate Acids, anhydrides of these acids, and the like can be used. These polybasic acids may be used alone or in combination of two or more.

  The polyether polyol preferably has a number average molecular weight of 100 to 4000. Although details will be described later, examples of the polyether polyol include polyether polyols of polymers or copolymers such as ethylene oxide, propylene oxide, and tetrahydrofuran. Specifically, known general-purpose materials such as polyethylene glycol, polypropylene glycol, and polytetramethylene glycol may be used, and polyethylene glycol is preferable. By containing the polyester polyol and / or polyether polyol in the above range, the adhesion particularly on the base film is greatly improved, and as a result, the blocking resistance and the laminate strength are improved.

  Similarly, if the number average molecular weight of the polyether polyol is less than 100, the polyurethane resin film tends to be hard, and the adhesion to the polyester film tends to decrease. When the number average molecular weight is greater than 4000, the polyurethane resin film tends to be brittle, and the blocking resistance of the ink film tends to be lowered. In addition, the number average molecular weight of polyether polyol was measured on the same conditions by the gel permeation chromatography (GPC) method similarly to the said polyester polyol.

  Examples of the diisocyanate compound used in the polyurethane resin in the liquid ink composition of the present invention include various known aromatic diisocyanates, aliphatic diisocyanates, and alicyclic diisocyanates 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, Melyl diisocyanate, isophorone diisocyanate (3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate; 5-isocyanato-1- (isocyanomethyl) -1,3,3-trimethylcyclohexane;), 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- Dimerisocyanate obtained by converting the carboxyl group of diisocyanate, 2,6-diisocyanate-benzyl chloride or dimer acid into an isocyanate group Anate. These diisocyanate compounds can be used alone or in admixture of two or more.

  Examples of the chain extender used in the polyurethane resin in the liquid ink composition of the present invention include ethylenediamine, propylenediamine, hexamethylenediamine, diethylenetriamine, triethylenetetramine, isophoronediamine, dicyclohexylmethane-4,4′-diamine and the like. 2-hydroxyethylethylenediamine, 2-hydroxyethylpropyldiamine, 2-hydroxyethylpropylenediamine, di-2-hydroxyethylethylenediamine, di-2-hydroxyethylenediamine, di-2-hydroxyethylpropylenediamine, 2-hydroxypropyl Also used are amines having a hydroxyl group in the molecule, such as ethylenediamine, di-2-hydroxypropylethylenediamine, and di-2-hydroxypropylethylenediamine. It can be. These chain extenders can be used alone or in admixture of two or more.

  Furthermore, the amine value of the polyurethane resin and / or polyurethane urea resin used in the liquid ink composition of the present invention is preferably 10.0 mgKOH / g or less. If the amine value exceeds 10.0 mg KOH / g, the anti-blocking property tends to be inferior, and the two-component stability after the addition of the curing agent is lowered. The range of 1.0 to 5.0 mgKOH / g is more preferable from the viewpoint of maintaining the plate fogging property, adhesiveness and extrusion laminate strength while maintaining good blocking resistance and two-component stability, and more preferably 1.0. It is in the range of ˜3.5 mg KOH / g.

As the organic solvent (B) 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, ketones such as acetone, methyl ethyl ketone, and methyl isobutyl ketone. Solvent solvents, ester solvents such as ethyl acetate, n-propyl acetate, butyl acetate, propylene glycol monomethyl ether acetate, alcohol solvents such as n-propanol, innopropanol, n-butanol, propylene glycol monomethyl ether, and the like. Can be used alone or in a mixture of two or more.
In recent years, it is more preferable not to use an aromatic solvent or a ketone solvent such as toluene or xylene from the viewpoint of the working environment.

Further, in the liquid ink composition of the present invention, the hydroxycarboxylic acid (C) is essential. The composition of the binder resin (A), the organic solvent (B), and the hydroxycarboxylic acid (C) is excellent in viscosity stability in both the one-component type that does not use a curing agent and the two-component type that uses a curing agent. Liquid ink is obtained.
Examples of the hydroxycarboxylic acid (C) include 2-hydroxybutanedioic acid (malic acid), (2R, 3S, 4R, 5R) -2,3,4,5,6-pentahydroxyhexanoic acid (gluconic acid), Examples include 2-hydroxypropanoic acid (lactic acid), 2-hydroxypropane-1,2,3-tricarboxylic acid (citric acid), and 2-hydroxyethanoic acid (glycolic acid).
The amount of the hydroxycarboxylic acid (C) added is preferably 0.001 to 1.0 mass%, more preferably 0.01 to 0.5 mass% of the total amount of the liquid ink composition. When the amount is less than 0.001% by mass, the effect of viscosity stability is not observed. When the amount exceeds 1.0% by mass, the viscosity of the ink itself and the stability of the two-component storage deteriorate due to a decrease in viscosity over time. There is a tendency that the printing quality is lowered and the retort resistance is lowered.

In the liquid ink composition of the present invention, water can be contained in the ink composition together with an organic solvent as a volatile component at a content of less than 10% by mass. Furthermore, the range of 1 to 5% by mass is particularly preferable because printability is improved.
In this case, the water may be added to an organic solvent to form a water-containing organic solvent, or a specific amount of water may be added separately.

Furthermore, a resin having a urea bond, such as a polyurethane polyurea resin, is effective for obtaining heat resistance in the ink film. And, since the urea bonds are linked by hydrogen bonds, the viscosity of the ink is increased, and the printability tends to deteriorate. In order to prevent such a phenomenon, it is preferable to contain water in the ink composition at a content of less than 10% by mass in order to reduce the viscosity of the resin bonded with urea bonds and hydrogen bonds. Moreover, it is also possible to reduce the used organic solvent component by addition of such water.
Furthermore, there is also a function of controlling the drying property of the ink by adding water. In particular, in the case of gravure printing, it is possible to clearly reproduce a gradation portion having a low ink transfer amount, which is a feature of the ink.

Furthermore, a vinyl chloride-vinyl acetate copolymer resin can be added to the liquid ink composition of the present invention.
The vinyl chloride vinyl acetate copolymer resin used in the liquid ink composition of the present invention is obtained, for example, by copolymerizing vinyl chloride and vinyl acetate, and the resin may have a hydroxyl group. Such vinyl chloride vinyl acetate copolymer resin having a hydroxyl group is obtained by copolymerizing vinyl chloride and vinyl acetate resin and then introducing a hydroxyl group by partially hydrolyzing, or at the time of polymerization, vinyl chloride or vinyl acetate. It can be obtained by introducing a hydroxyl group by adding and copolymerizing a component having a hydroxyl group other than the above, for example, 2-hydroxyethyl methacrylate. A commercially available product may be used as the vinyl chloride / vinyl acetate copolymer resin having a hydroxyl group.
In the vinyl chloride vinyl acetate copolymer resin having a hydroxyl group, the properties of the resin film and the resin dissolution behavior are determined by the content ratio of the hydroxyl group-containing structure such as vinyl chloride skeleton, vinyl acetate skeleton, and vinyl alcohol skeleton. That is, vinyl chloride imparts toughness and hardness of the resin coating, vinyl acetate imparts adhesiveness and flexibility, and hydroxyl groups such as vinyl alcohol impart good solubility in polar solvents. In addition, it is preferable to contain 0.1-5.0 mass% in conversion of solid content in all the resin components.

  Examples of the colorant used in the liquid ink composition of the invention include organic and inorganic pigments and dyes used in general inks, paints, and recording agents. Organic pigments include azo, phthalocyanine, anthraquinone, perylene, perinone, quinacridone, thioindigo, dioxazine, isoindolinone, quinophthalone, azomethine azo, dictopyrrolopyrrole, isoindoline, etc. Pigments. Indigo ink is copper phthalocyanine, and transparent yellow ink is C.I. I. Pigment No Yellow 83 is preferably used.

  For example, pigment C.I. I. Black7, Y12, Y13, Y14, Y17, Y83, Y74, Y-154, Y180, R57: 1, R122, R48: 1, R48: 2, R48: 3, R53: 1, R146, R-150 R-166, R170, R184, R185, V19, V23, V32, O13, O16, O34, G7, G36, B15: 3, B15: 4, W6 and the like.

  Examples of the inorganic pigment include carbon black, titanium oxide, zinc oxide, zinc sulfide, barium sulfate, calcium carbonate, chromium oxide, silica, bengara, aluminum, mica (mica), and the like. From the viewpoints of cost and coloring power, it is preferable to use titanium oxide for white ink, carbon black for black ink, aluminum for silver ink, and mica for pearl ink. Aluminum is in the form of powder or paste, but is preferably used in the form of paste from the viewpoint of handling and safety, and whether to use leafing or non-leafing is appropriately selected from the viewpoint of brightness and concentration. It is preferable that the colorant is contained in an amount sufficient to ensure the density and coloring power of the ink, that is, in a proportion of 1 to 50% by mass with respect to the total mass of the ink. Moreover, a coloring agent can be used individually or in combination of 2 or more types.

  These organic pigments and inorganic pigments also have the effect of improving the drying properties and printing characteristics of the ink by the addition of the moisture described above.

(Normal production method)
The liquid ink composition of the present invention can be produced by, for example, adding a colorant, an extender pigment, a solvent, a hydroxycarboxylic acid, and, if necessary, an antistatic agent, an antiblocking agent, a plasticizer to a polyurethane resin. In addition, surfactants for improving ink flowability and dispersibility, or resins compatible with polyurethane resins are used in a range where thickening and gelation do not occur over time, ball mills, attritors, sand mills, etc. By kneading using a normal printing ink production apparatus. In particular, the addition of an antistatic agent is effective in suppressing static electricity troubles during printing, called whiskers and lightning stripes, which are likely to occur when using ester solvents and ketone solvents.

  The present invention also provides a printed material obtained by printing the above-described liquid ink composition, and a laminate laminate having a printed layer formed by printing the liquid ink composition.

Hereinafter, the present invention will be specifically described with reference to examples. In the examples, “part” represents mass part, and “%” represents mass%.
In addition, the measurement of the weight average molecular weight (polystyrene conversion) of the polyurethane resin by GPC (gel permeation chromatography) in the present invention was performed under the following conditions using an HLC8220 system manufactured by Tosoh Corporation.
Separation column: 4 TSKgelGMH _HR- N manufactured by Tosoh Corporation are used. Column temperature: 40 ° C. Moving layer: Tetrahydrofuran manufactured by Wako Pure Chemical Industries, Ltd. Flow rate: 1.0 ml / min. Sample concentration: 0.4% by mass. Sample injection volume: 100 microliters. Detector: differential refractometer.
The amine value indicates the number of mg of potassium hydroxide (KOH) equivalent to the equivalent amount of hydrochloric acid required to neutralize the amino group contained in 1 g of polyurethane resin. As the measurement method, 30 mL of neutral ethanol was added to and dissolved in a sample accurately weighed P grams, and the resulting solution was titrated with a 0.2 mol / L ethanolic hydrochloric acid solution (titer f). . The time when the color of the solution changed from green to yellow was regarded as the end point, and the amine value was determined by the following (formula 2) using the titration amount (HmL) at this time.
In addition, the said sample refers to the polyurethane resin solution obtained by each synthesis example, and calculates it by solid content mass conversion 30%.
Amine number = (H × f × 0.2 × 56.108) /P/0.3 [mg KOH / g]

(Preparation of polyurethane resin solution P)
Number average molecular weight obtained from adipic acid and 3-methyl-1,5-pentanediol in a 1 liter four-necked flask equipped with a stirrer, thermometer, Dimroth type reflux condenser, and nitrogen gas inlet tube 264.20 parts of 5100 polyester polyol was charged, nitrogen gas was passed, and the temperature was raised to 50 ° C. while stirring. Subsequently, 28.01 parts of isophorone diisocyanate was added, and the reaction was continued at 90 ° C. until the NCO%, which is the residual ratio of isocyanate groups, reached 1.99%. After cooling, 157.34 parts of n-propyl acetate was added to obtain a urethane prepolymer solution (B2) having an isocyanate group at the terminal.
Subsequently, 1-amino-3-aminomethyl-3,5,5-trimethylcyclohexane was added to a 1 liter four-necked flask equipped with a stirrer, a thermometer, a Dimroth reflux condenser, and a nitrogen gas introduction tube. 10.96 parts, 1.37 parts of monoethanolamine, 411.00 parts of n-propyl acetate, 142.00 parts of n-propyl alcohol, and 449.55 parts of urethane prepolymer solution (B2) are added, and the mixture is heated at 45 ° C. for 4 hours. The reaction was performed to obtain a polyurethane resin solution (P) having a solid content of 30%, a weight average molecular weight of 48,000, and an amine value of 1.5 (mgKOH / g).

(Preparation of vinyl chloride vinyl acetate copolymer resin solution V)
Vinyl chloride vinyl acetate copolymer resin having a hydroxyl group used in combination with a polyurethane resin (resin monomer composition is mass% vinyl chloride / vinyl acetate / vinyl alcohol = 92/3/5, hydroxyl value (mgKOH) = 64) is acetic acid. A 15% solution was made with n-propyl, and this was made into a vinyl chloride resin solution (V).

Example 1
25 parts of polyurethane resin solution P (solid content 30%), 10 parts of vinyl chloride resin solution V (15% solid content), 45 parts of JR-780 manufactured by Titanium Oxide Pigment Co., Ltd., 10 parts of isopropyl alcohol, ethyl acetate A mixture of 27 parts was kneaded using a dyno mill (manufactured by Willy et Baccophenon), and 3 parts of water and α-hydroxysuccinic acid (malic acid) were further added to the obtained white kneaded meat base ink (W). Of isopropyl alcohol: ethyl acetate = 1: 1 (solid content 5%) was added to prepare a liquid white ink of the present invention.

(Examples 2-7, Comparative Examples 1-7)
About Examples 2-7, after producing white ground meat base ink (W) in the same procedure as Example 1, 3 parts of water and propyl alcohol of various hydroxycarboxylic acids: ethyl acetate = 1: 1 part of a mixed solution (solid content: 5%) was added to prepare a liquid white ink.
For Comparative Examples 1 to 5, other acid compounds were added, and for Comparative Example 6 styrene maleic acid resin was added with 1 part of a mixed solution of sopropyl alcohol: ethyl acetate = 1: 1 (solid content 5%), Liquid white inks were respectively prepared.
In Comparative Example 7, the acid compound and water were not added, and 4 parts of a mixed solution of isopropyl alcohol: ethyl acetate = 1: 1 was added to adjust the total amount to 100 parts.

  The following evaluation was implemented about the liquid white ink of Examples 1-7 obtained above and Comparative Examples 1-7.

(Viscosity measurement)
Liquid white ink was used by Zaan Cup No. 4 was used to measure the viscosity at a liquid temperature of 25 ° C. immediately after ink production.

(Viscosity stability)
Each liquid white ink was collected in a glass bottle and stored at 50 ° C. for 28 days. Thereafter, the viscosity was measured at 25 ° C., and the change in the viscosity before storage with one liquid was evaluated. The evaluation criteria were as follows.
(Evaluation)
○: No viscosity change Viscosity change is less than 2 seconds Δ: Viscosity change is small Viscosity difference is 2 seconds or more and less than 5 seconds X: Viscosity change is very large Viscosity difference is 5 seconds or more

(2 liquid stability)
Liquid white ink was collected in a glass bottle, and CVL NO. After adding 4% by weight of 10 hardener (isocyanate curing agent: manufactured by DIC) and storing at 25 ° C. for 1 day, the viscosity was measured and the change in viscosity from before storage was evaluated. The evaluation criteria were as follows.
(Evaluation)
○: No viscosity change Viscosity change is less than 2 seconds Δ: Viscosity change is small Viscosity difference is 2 seconds or more and less than 5 seconds X: Viscosity change is large Viscosity difference is 5 seconds or more

(Printability test: Scratch test)
Liquid white ink was diluted with a mixed organic solvent in the same ratio used for ink preparation, and diluted with Zaan Cup No. 3 manufactured by Kogaisha Co., Ltd. for 16 seconds. Using a gravure printing machine (manufactured by DIC Engineering Co., Ltd.) to which a gravure plate having a plate depth of 3 μm is attached, biaxially stretched polyester film (Toyobo Co., Ltd., E-5100 thickness) The printing was performed on the treated surface having a thickness of 12 μm. And the transfer degree (scratch degree) of the ink to the printing part of printed matter was evaluated. In the blur test, evaluation was performed at a printing speed of 300 m / min at a circumference of 600 mmφ of the gravure plate. For the purpose of investigating the change over time, each of the ink immediately after production and the ink stored at 50 ° C. for 28 days were tested. The evaluation criteria were as follows.
(Evaluation)
○: No blurring △: Scratch generation a little ×: Scratching occurs frequently

(Printability test: Plate fog test)
Of the printed matter when printed under the above-described blur test conditions, the degree of stain (plate fog) of the non-printed area was evaluated. For the purpose of investigating the change over time, each of the ink immediately after production and the ink stored at 50 ° C. for 28 days were tested. The evaluation criteria were as follows.
(Evaluation)
○: No print stains △: Print stains can be confirmed slightly ×: Print stains are severe

(concentration)
Using printed matter when printed under the above-mentioned blur test conditions, the reflection density of each printed matter was compared with a reflection densitometer X-RITE530. For the purpose of investigating the change over time, each of the ink immediately after production and the ink stored at 50 ° C. for 28 days were tested. The evaluation criteria were as follows.
(Evaluation)
○: Reflection density value is 2.0 or more Δ: Reflection density value is 1.5 or more and less than 2.0 ×: Reflection density value is less than 1.5

(Lamination strength)
A urethane-based adhesive is used for the printed matter, and an unstretched polypropylene film (ZK93KM 70 μm, manufactured by Toray Synthetic Film Co., Ltd.) by a dry laminating machine (manufactured by DIC Engineering) with a dry laminate adhesive Dick Dry LX-703VL / KR-90 (manufactured by DIC). ) And the peel strength was measured after aging at 40 ° C. for 5 days. For the purpose of investigating the change over time, each of the ink immediately after production and the ink stored at 50 ° C. for 28 days were tested. The evaluation criteria were as follows.
○: The laminate strength is 500 (g / 15 mm) or more, and the strength is sufficient.
(Triangle | delta): Laminate intensity | strength is 300 or more and less than 500 (g / 15mm), and intensity | strength is slightly insufficient.
X: The laminate strength is less than 300 (g / 15 mm) and the strength is insufficient.

(Retort resistance)
After the above-mentioned printed matter was dry laminated, the laminate was made into a bag, and a water / salad oil mixture was added as the contents. After sealing, the laminate was heated at 125 ° C. for 30 minutes, and then visually checked for the presence or absence of lami floating. For the purpose of investigating the change over time, each of the ink immediately after production and the ink stored at 50 ° C. for 28 days were tested. The determination criteria were as follows.
○: There is no Lami float.
(Triangle | delta): Only a part was delaminated or the blister produced slightly.
X: Full surface delamination occurred.

  From the above results, the liquid ink composition of the present invention does not use a curing agent while maintaining basic properties such as printability such as a blurring test, plate fogging test, density stability, laminate strength, and retort resistance 1 Both the liquid type and the two-liquid type using a curing agent are excellent in viscosity stability.

  The liquid ink composition of the present invention is a low-toluene type low-viscosity liquid ink that is environmentally and hygienic in gravure printing or flexographic printing, and is intended for industrial products such as food packaging, sanitary, cosmetics, and electronic parts. Can be widely deployed in flexible packaging applications.

Claims (10)

A liquid ink composition comprising a binder resin (A), an organic solvent (B), and a hydroxycarboxylic acid (C). The liquid ink composition according to claim 1, wherein the binder resin (A) is a polyurethane resin and / or a polyurethane polyurea resin. The liquid ink composition of Claim 1 or 2 which contains less than 10 mass% of water in a liquid ink composition. The liquid ink composition according to any one of claims 1 to 3, wherein the binder resin (A) further contains a vinyl chloride-vinyl acetate copolymer resin. Furthermore, the liquid ink composition as described in any one of Claims 1-4 containing a coloring agent (D). The liquid ink composition according to claim 1, wherein the polyurethane resin and / or polyurethane urea resin has an amino group. The liquid ink composition according to any one of claims 1 to 6, wherein an amine value in terms of solid content of the polyurethane resin and / or polyurethane urea resin is 10.0 mgKOH / g or less. The liquid ink composition according to any one of claims 1 to 7, wherein the organic solvent (B) does not contain an aromatic organic solvent and / or a ketone solvent. The printed matter formed by printing the liquid ink composition as described in any one of Claims 1-8. A laminate laminate having a printed layer formed by printing the liquid ink composition according to any one of claims 1 to 8.