CN110546215B - Liquid ink composition, printed matter, and laminated laminate - Google Patents

Abstract

The invention provides a liquid ink composition which is easy to recover volatile solvent in the ink composition and has excellent ink transferability and lamination strength. The liquid ink composition of the present invention is characterized by containing a polyurethane resin (A) and an organic solvent (B), wherein the polyurethane resin (A) uses a polyester polyol and/or a polyether polyol, and an alkanolamine as reaction raw materials, has a weight average molecular weight in the range of 30000-70000, has a urea bond concentration of 0.8mmol/g or less, and has a hydroxyl value of 11.0mgKOH/g or less.

Description

Liquid ink composition, printed matter, and laminated laminate

Technical Field

The present invention relates to a liquid ink composition used in gravure ink and flexo ink for laminating flexible packages. In particular, the present invention relates to a liquid ink composition which facilitates recovery of a volatile solvent in the ink composition and has both excellent ink transferability and excellent lamination strength.

Background

In recent years, efforts have been made to deal with the problem of air pollution caused by substances such as nitrogen oxides, which decrease stratospheric ozone around the earth environment and increase tropospheric ozone on the contrary, forest damage caused by acid rain, which is thought to involve photochemical ozone, and the like, and on the other hand, VOC is a generic term of volatile organic compounds, and has brought about various problems from the viewpoints of influence on the human body and labor hygiene in addition to the problems related to air pollution, global warming, and many other environmental problems.

In the gravure and flexo printing industries, there is a demand for a solution to VOC generation sources from the printing field by using low VOC materials for high-concentration inks, aqueous inks, and the like, and by sealing the printing unit. Further, there is an increasing demand for recycling the solvent contained in the used or waste ink.

Therefore, a solvent recovery and reuse type printing ink composition characterized in that 95% or more of volatile components contains an organic solvent 2 component has been disclosed (for example, see patent document 1).

Further, an organic solvent-based printing ink composition in which an ester-based solvent mainly containing ethyl acetate and an alcohol-based solvent mainly containing n-propanol are used in a specific mass ratio range is disclosed (for example, see patent documents 2 and 3). Further, a solvent recovery and reuse type printing ink composition containing 2 or more solvents selected from hydrocarbon solvents, ketone solvents, ester solvents, alcohol solvents, and glycol solvents is disclosed (for example, see patent document 4). However, these compositions are compositions obtained by simplifying and purifying the solvent composition in order to facilitate solvent recovery, and it is difficult to say that basic characteristics such as ink transferability and lamination strength required for printing ink in printing of these compositions are absolutely sufficient.

Patent document 1: japanese laid-open patent publication No. 2008-019427

Patent document 2: japanese laid-open patent publication No. 2008-266370

Patent document 3: japanese patent laid-open No. 2008-265032

Patent document 4: WO2007/145214 publication

Disclosure of Invention

Problems to be solved by the invention

The invention provides a liquid ink composition which facilitates recovery of a volatile solvent in the ink composition and has excellent ink transferability and lamination strength.

Means for solving the problems

The invention discovers that: the liquid ink composition containing the urethane resin (a) having a specific physical property value and using a specific reaction material and the organic solvent (B) is very effective for solving the problem.

That is, the present invention relates to a liquid ink composition containing a polyurethane resin (a) and an organic solvent (B), wherein the polyurethane resin (a) is obtained by using a polyester polyol and/or a polyether polyol, and an alkanolamine as reaction raw materials, has a weight average molecular weight in the range of 30000 to 70000, has a urea bond concentration of 0.8mmol/g or less, and has a hydroxyl value of 11.0mgKOH/g or less.

Further, the present invention relates to a liquid ink composition, wherein the alkanolamine is an alkanolamine having 2 or more hydroxyl groups.

The present invention also relates to a liquid ink composition, wherein the polyester polyol has a number average molecular weight of 3000 to 7000.

Further, the present invention relates to a liquid ink composition further containing a vinyl chloride-vinyl acetate copolymer resin (C) having a hydroxyl group.

Further, the present invention relates to a liquid ink composition, wherein the hydroxyl value of the vinyl chloride-vinyl acetate copolymer resin (C) having a hydroxyl group is 50 to 200mgKOH/g, and the content ratio of a vinyl chloride component in the copolymer resin is 80 to 95% by mass.

Further, the present invention relates to a liquid ink composition, wherein the amine value of the polyurethane resin (a) is 6.5mgKOH/g or less.

Further, the present invention relates to a liquid ink composition, wherein the organic solvent (B) contains an ester-based solvent (B-1) in an amount of 90 mass% or more based on the total amount of the organic solvent (B), and an alcohol-based solvent (B-2) in an amount of 0.1 mass% or more based on the total amount of the organic solvent (B), the ester-based solvent (B-1) is one or more selected from the group consisting of ethyl acetate, n-propyl acetate, butyl acetate, and propylene glycol monomethyl ether acetate, and the alcohol-based solvent (B-2) is one or more selected from the group consisting of methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, and 2-butanol.

The present invention also relates to a printed matter obtained by printing the liquid ink composition.

The present invention also relates to a laminated laminate having a printed layer formed by printing the liquid ink composition.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, it is possible to provide a liquid ink composition which is easy to recover a volatile solvent in the ink composition and has excellent ink transferability and lamination strength.

Detailed Description

The present invention will be described in detail. In the present invention, the term "liquid ink" refers to both of the following "printing inks" and "liquid ink" refers to: typical liquid inks used in printing methods, such as gravure printing methods using an intaglio plate and flexographic printing methods using a flexographic plate, are low-viscosity (approximately 1000mPa · s or less) inks used for printing methods in which ink is once deposited on a plate and then transferred to paper.

All of the "parts" represent "parts by mass".

The liquid ink composition of the present invention is a liquid ink composition containing a polyurethane resin (A) and an organic solvent (B), wherein the polyurethane resin (A) is obtained by using a polyester polyol and/or a polyether polyol, and an alkanolamine as reaction raw materials, has a weight average molecular weight in the range of 30000 to 70000, has a urea bond concentration of 0.8mmol/g or less, and has a hydroxyl value of 11.0mgKOH/g or less.

The polyurethane resin (a) used in the liquid ink composition of the present invention is required to use an alkanolamine, a polyester polyol and/or a 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 (a) tends to be hardened, and the adhesiveness to the polyester film tends to be low. When the number average molecular weight is more than 7000, the urethane resin film tends to be fragile, and the blocking resistance of the ink film tends to be low. When the amount of the polyester polyol is less than 1 part by mass based on 100 parts by mass of the polyurethane resin (a), the solubility of the polyurethane resin (a) in a ketone, ester, or alcohol solvent is lowered, and thus the adhesion particularly to a high-performance barrier film tends to be lowered. Further, the ink film has low re-solubility in the solvent, and the color tone reproducibility of the printed matter tends to be low. When the amount exceeds 50 parts by mass, the ink coating tends to be excessively soft and blocking resistance tends to be poor.

The number average molecular weight of the polyester polyol is a value measured by a Gel Permeation Chromatography (GPC) method under the following conditions.

A measuring device: high-speed GPC apparatus (HLC-8220 GPC, manufactured by Tosoh corporation)

A chromatographic column: the following columns manufactured by Tosoh corporation were used in series.

"TSKgel G5000" (7.8 mmI.D.. times.30 cm). times.1 roots

"TSKgel G4000" (7.8mm I.D.. times.30 cm). times.1 roots

"TSKgel G3000" (7.8 mmI.D.. times.30 cm). times.1 roots

"TSKgel G2000" (7.8 mmI.D.. times.30 cm). times.1 roots

A detector: RI (differential refractometer)

Temperature of the column: 40 deg.C

Eluent: tetrahydrofuran (THF)

Flow rate: 1.0 mL/min

Sample introduction amount: 100 μ L (tetrahydrofuran solution with a sample concentration of 0.4% by mass)

Standard sample: the standard 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 polyester polyol, for example, a polyol obtained by a known esterification reaction of a compound having 2 or more hydroxyl groups and a polybasic acid can be used.

The compound having 2 or more hydroxyl groups is a compound used as a chain extender, and 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, 1, 4-butanediol, 2-butyl-2-ethyl-1, 3-propanediol, 1, 2-propanediol, 2-methyl-1, 3-propanediol, diols having a branched structure such as 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; aliphatic polyols such as trimethylolpropane, trimethylolethane, pentaerythritol, sucrose, methylene glycol, glycerol, and sorbitol; and aromatic polyols such as bisphenol A, 4 ' -dihydroxybiphenyl, 4 ' -dihydroxydiphenyl ether, 4 ' -dihydroxydiphenyl sulfone, hydrogenated bisphenol A, and hydroquinone, which have a number average molecular weight in the range of 50 to 400. These chain extenders may be used alone, or 2 or more of them may be used in combination.

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, phthalic acid, and anhydrides of these acids. These polybasic acids may be used alone or in combination of 2 or more.

The polyether polyol preferably has a number average molecular weight of 100 to 4000. As the polyether polyol, polyether polyols of polymers or copolymers of ethylene oxide, propylene oxide, tetrahydrofuran, and the like are mentioned in detail later. Specifically, a publicly known polyether polyol such as polyethylene glycol, polypropylene glycol, polytetramethylene glycol and the like can be used, and among them, polyethylene glycol is preferable. When the polyester polyol and/or the polyether polyol are contained within the above range, the adhesion particularly to the base film is greatly improved, and as a result, the blocking resistance and the lamination strength are excellent.

Similarly, when the number average molecular weight of the polyether polyol is less than 100, the coating film of the polyurethane resin (a) tends to be hardened, and the adhesiveness to the polyester film tends to be lowered. When the number average molecular weight is more than 4000, the urethane resin film tends to be fragile, and the blocking resistance of the ink film tends to be lowered. When the amount of the polyester polyol is less than 1 part by mass based on 100 parts by mass of the polyurethane resin (a), the solubility of the polyurethane resin (a) in a ketone, ester, or alcohol solvent is lowered, and thus the adhesiveness particularly to a high-performance barrier film tends to be lowered. Further, the ink film has a tendency to have reduced re-solubility in the solvent, and the printed matter tends to have reduced color tone reproducibility. When the amount exceeds 50 parts by mass, the ink coating tends to be excessively soft and blocking resistance tends to be poor. The number average molecular weight of the polyether polyol is measured by a Gel Permeation Chromatography (GPC) method based on the same conditions as the above polyester polyol.

Examples of the polyether polyol include polyether polyols of polymers or copolymers of oxymethylene, oxyethylene, tetrahydrofuran, and the like.

The polyester polyol and/or polyether polyol is preferably used in a proportion of 1 to 50% by mass relative to the total amount of the polyurethane resin (a).

Examples of the diisocyanate compound used for the polyurethane resin (a) in the liquid ink composition of the present invention include various known aromatic diisocyanates, aliphatic diisocyanates, alicyclic diisocyanates, and the like, which are generally used for the production of polyurethane resins. For example, 1, 5-naphthalene diisocyanate, 4 ' -diphenylmethane diisocyanate, 4 ' -diphenyldimethylmethane diisocyanate, 4 ' -dibenzylisocyanate, dialkyldiphenylmethane diisocyanate, tetraalkyldiphenylmethane diisocyanate, 1, 3-phenylene diisocyanate, 1, 4-phenylene diisocyanate, toluene diisocyanate, butane-1, 4-diisocyanate, hexamethylene diisocyanate, isopropylidene diisocyanate, methylene diisocyanate, 2, 4-trimethylhexamethylene diisocyanate, lysine diisocyanate, cyclohexane-1, 4-diisocyanate, xylylene diisocyanate, isophorone diisocyanate, diol diisocyanate (ジメリ - ルジイソシアネ - ト), and the like, Isophorone diisocyanate (3-isocyanatomethyl-3, 5, 5-trimethylcyclohexyl isocyanate; 5-isocyanato-1- (isocyanomethyl) -1, 3, 3-trimethylcyclohexane;), dicyclohexylmethane-4, 4' -diisocyanate, 1, 3-bis (isocyanatomethyl) cyclohexane, methylcyclohexane diisocyanate, norbornane diisocyanate, m-tetramethylxylylene diisocyanate, 4, 4-diphenylmethane diisocyanate, tolylene diisocyanate, bis-chloromethyl-diphenylmethane-diisocyanate, 2, 6-diisocyanate-benzyl chloride, dimeric diisocyanate obtained by converting the carboxyl group of dimer acid into an isocyanate group, and the like. These diisocyanate compounds may be used alone or in combination of 2 or more.

As the chain extender used for the polyurethane resin (a) in the liquid ink composition of the present invention, amines having a hydroxyl group in the molecule, such as ethylenediamine, propylenediamine, hexamethylenediamine, diethylenetriamine, triethylenetetramine, isophoronediamine, dicyclohexylmethane-4, 4' -diamine, and 2-hydroxyethylethylenediamine, 2-hydroxyethylpropyldiamine, 2-hydroxyethylpropylenediamine, di-2-hydroxyethylethylenediamine, di-2-hydroxyethylpropylenediamine, 2-hydroxypropylethylenediamine, di-2-hydroxypropylethylenediamine, and di-2-hydroxypropylethylenediamine, can be used. These chain extenders may be used alone or in combination of 2 or more.

As the terminal blocking agent for the purpose of stopping the reaction used for the polyurethane resin (a) in the liquid ink composition of the present invention, an alkanolamine is essential. Examples of the alkanolamine include monoethanolamine, diethanolamine, dipropanolamine and the like. When it is desired to introduce a carboxyl group into the polyurethane resin, an amino acid such as glycine or L-alanine may be used as an auxiliary reaction terminator. These terminal chain-capping agents may be used alone or in combination of 2 or more.

Further, if an alkanolamine having 2 or more hydroxyl groups is used, the adhesion and the lamination strength of the ink composition can be further improved. By having 2 or more hydroxyl groups, when a printed matter printed using the liquid ink composition of the present invention is dry-laminated with a laminating adhesive, the reaction points with a curing agent of the laminating adhesive are further increased, as compared with the case where the hydroxyl group is 1, and thus the laminating strength is improved. Examples of the alkanolamine having 2 or more hydroxyl groups include diethanolamine and dipropanolamine.

The urethane resin (a) in the liquid ink composition of the present invention can be prepared, for example, by reacting a polyethylene glycol and a polyol in combination with a diisocyanate compound at an excess ratio of isocyanate groups to obtain an isocyanate group-terminated prepolymer, and dissolving the prepolymer in an appropriate solvent, that is, an ester-based solvent such as ethyl acetate, propyl acetate, or butyl acetate, which is generally used as a solvent for gravure ink; ketone solvents such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; alcohol solvents such as methanol, ethanol, isopropanol, and n-butanol; hydrocarbon solvents such as toluene, xylene, methylcyclohexane, and ethylcyclohexane; or a mixed solvent thereof, with a chain extender and/or a terminal blocking agent, or by a one-shot process in which polyethylene glycol and a polyol, a diisocyanate compound, a chain extender and/or a terminal blocking agent are reacted at once in an appropriate solvent as described above. Among these methods, in order to obtain a uniform polyurethane resin, it is preferable to prepare based on a two-step process. When the polyurethane resin is produced by the two-stage process, the reaction is preferably carried out so that the total (equivalent ratio) of the amino groups of the chain extender and/or the terminal chain terminator is 1/0.9 to 1.3. When the equivalent ratio of the isocyanate group to the amino group is less than 1/1.3, the chain extender and/or the terminal chain-blocking agent remain unreacted, and the polyurethane resin may be yellowed or an odor may be generated after printing.

In recent years, it is more preferable not to use aromatic solvents such as toluene and xylene, and ketone solvents from the viewpoint of working environment.

The weight average molecular weight of the polyurethane resin (A) thus obtained is within a range of 30000 to 70000, more preferably within a range of 35000 to 65000. When the weight average molecular weight of the urethane resin is less than 30000, the viscosity of the obtained ink composition tends to be low in terms of blocking resistance, strength of a printed film, oil resistance and the like, and when it exceeds 70000, the viscosity of the obtained ink composition tends to be high and the gloss of the printed film tends to be low.

The weight average molecular weight (in terms of polystyrene) by GPC (gel permeation chromatography) in the present invention was measured using the HLC8220 system manufactured by tokyo corporation under the following conditions.

Separating the chromatographic column: TSKgelGMH prepared from 4 Tosoh_HR-N. Temperature of the column: at 40 ℃. Moving the layer: and tetrahydrofuran manufactured by Wako pure chemical industries, Ltd. Flow rate: 1.0 ml/min. Sample concentration: 1.0% by weight. Sample introduction amount: 100 microliters. A detector: a differential refractometer.

The viscosity was measured at 25 ℃ with a type B viscometer manufactured by Tokimec corporation.

The urethane resin (A) used in the liquid ink composition of the present invention is required to have a urea bond concentration of 0.8mmol/g or less and a hydroxyl value of 11.0mgKOH/g or less. When the urea bond concentration is higher than 0.8mmol/g, the hardness of the composition increases more than necessary and the flexibility is lost, so that the lamination strength tends to decrease and the fluidity also deteriorates, and therefore the high light transferability of the printed matter tends to decrease due to thickening change of the viscosity of the ink during printing. When the hydroxyl value is more than 11.0mgKOH/g, the water resistance tends to be low, and the lamination strength after retort treatment tends to be low. From the viewpoint of maintaining adhesiveness and lamination strength, the urea bond concentration is more preferably in the range of 0.3 to 0.8mmol/g, and the hydroxyl value is more preferably in the range of 0.5 to 10.0 mgKOH/g.

The relationship between the urea bond concentration can be calculated by the following formula (1).

Urea bond concentration ═ X1000/S formula (1) [ (X1/eq1+ X2/eq2+ … Xi/eqi) - { (W1 × OH1+ W2 × OH2+ … + Wi × OHi)/56100} ] × 1000/S formula (1)

When a plurality of isocyanate compounds and polyols are used, the isocyanate compound 1, the isocyanate compound 2 to the isocyanate compound i, and the polyol 1, the polyol 2 to the polyol i are calculated.

In the formula (1), the symbols are as follows.

X1: mass of isocyanate Compound 1

eq 1: isocyanate equivalent of isocyanate Compound 1

X2: mass of isocyanate Compound 2

eq 2: isocyanate equivalent of isocyanate Compound 2

Xi: mass of isocyanate Compound i

eqi: isocyanate equivalent of isocyanate Compound i

W1: quality of polyol 1

OH 1: hydroxyl number of polyol 1

W2: mass of polyol 2

OH 2: hydroxyl number of polyol 2

And Wi: quality of polyol i

An Ohi: hydroxyl number of polyol i

S: mass of polyurethane resin solid content

Further, the amine value of the polyurethane resin (a) used in the liquid ink composition of the present invention is preferably 6.5mgKOH/g or less. When the amine value is more than 6.5mgKOH/g, the blocking resistance tends to be poor. From the viewpoint of maintaining satisfactory blocking resistance and maintaining plate fogging property, adhesiveness and extrusion lamination strength, the range of 1.0 to 5.0mgKOH/g is more preferable, and the range of 1.0 to 3.5mgKOH/g is even more preferable.

The content of the urethane resin (a) used in the liquid ink composition of the present invention in the ink is 5 mass% or more based on the total mass of the ink, from the viewpoint of sufficient adhesiveness of the ink to a print target, and is preferably 50 mass% or less, and more preferably in the range of 10 to 40 mass% from the viewpoint of an appropriate ink viscosity and the working efficiency in ink production and printing.

As the organic solvent (B) used in the liquid ink composition of the present invention, various organic solvents can be used, and examples thereof include aromatic organic solvents such as toluene and xylene, ketone solvents such as acetone, methyl ethyl ketone and methyl isobutyl ketone, ester solvents such as ethyl acetate, n-propyl acetate, butyl acetate and propylene glycol monomethyl ether acetate, and alcohol solvents such as n-propanol, isopropanol, n-butanol and propylene glycol monomethyl ether, and these can be used alone or in a mixture of 2 or more.

Among the organic solvents (B), from the viewpoint of ease of adjustment of drying properties and solubility of the polyurethane resin based on an appropriate evaporation rate at the time of printing, it is preferable that ester-based solvent (B-1) is contained in an amount of 90 mass% or more of the total amount of the organic solvents (B), and alcohol-based solvent (B-2) is contained in an amount of 0.1 mass% or more of the total amount of the organic solvents (B), the ester-based solvent (B-1) is one or more selected from the group consisting of ethyl acetate, n-propyl acetate, butyl acetate, and propylene glycol monomethyl ether acetate, the alcohol-based solvent (B-2) is one or more selected from the group consisting of ethanol, 1-propanol, 2-propanol, 1-butanol, and 2-butanol, and if the composition is limited to one not containing ketones, the coloring of the waste solvents is small, easy purification and more efficient solvent recovery.

When the ester-based solvent (b-1)/alcohol-based solvent (b-2) is used in combination under the above conditions, the azeotropic point of water is low, and therefore, the water mixed in during printing can be easily removed. Further, the mixed solvent can be recovered in high yield, and the diluted solvent can be easily reused.

For example, isopropyl acetate (IPAC) and n-propyl acetate (NPAC) are by-produced in the purification step after recovery for isopropyl alcohol (IPA) as 2-propanol and n-propyl alcohol (NPA) as 1-propanol, respectively, and therefore, when the ester-based solvent is n-propyl acetate (NPAC), the purification step can be further simplified by selecting n-propyl alcohol (NPA) as the alcohol solvent (b-2).

Further, the liquid ink composition of the present invention may contain a vinyl chloride-vinyl acetate copolymer resin (C).

The vinyl chloride-vinyl acetate copolymer resin (C) preferably has a hydroxyl group, preferably has a hydroxyl value of 50 to 200mgKOH/g, and the content of the vinyl chloride component in the copolymer resin is 80 to 95 mass%. When the vinyl chloride-vinyl acetate copolymer resin (C) is present, the ink film tends to have an increased cohesive force and to have good blocking resistance. By further using the blocking resistance agent in combination, the improvement of blocking resistance becomes better.

The vinyl chloride-vinyl acetate copolymer resin having a hydroxyl group used in the liquid ink composition of the present invention can be obtained by two methods. One is obtained by copolymerizing vinyl chloride monomer, vinyl acetate monomer and vinyl alcohol in an appropriate ratio. Alternatively, the catalyst is obtained by copolymerizing vinyl chloride with vinyl acetate and then saponifying a part of the vinyl acetate. The vinyl chloride-vinyl acetate copolymer resin having a hydroxyl group determines the properties of the resin film and the resin dissolution behavior by the monomer ratio of vinyl chloride, vinyl acetate and vinyl alcohol. That is, vinyl chloride imparts toughness and hardness to the resin film, vinyl acetate imparts adhesiveness and flexibility, and vinyl alcohol imparts good solubility to polar solvents.

When liquid ink is used as laminating ink for flexible packaging, the vinyl chloride-vinyl acetate copolymer resin having a hydroxyl group is present in an appropriate monomer ratio because all of the properties such as adhesiveness, blocking resistance, lamination strength, suitability for retort treatment, and suitability for printing need to be satisfied. That is, the vinyl chloride is preferably 80 to 95 mass% based on the vinyl chloride-vinyl acetate copolymer resin having a hydroxyl group. If the content is less than 80% by mass, the toughness of the resin film is poor, and the blocking resistance is lowered. When the content exceeds 95% by mass, the resin coating film becomes too hard, and the adhesiveness is lowered. The hydroxyl value obtained from vinyl alcohol is preferably 50 to 200 mgKOH/g. When the content is less than 50mgKOH/g, the solubility in a polar solvent is poor, and the printability tends to be poor. When the concentration exceeds 200mgKOH/g, the water resistance is lowered, and the adaptability to the sterilization treatment and the retort treatment of the boiling vessel is poor.

Examples of the resin to be used in combination as needed in the liquid ink composition of the present invention include resins other than the above-mentioned polyurethane resin and vinyl chloride-vinyl acetate copolymer resin, for example, chlorinated polypropylene resin, ethylene-vinyl acetate copolymer resin, vinyl acetate resin, polyamide resin, acrylic resin, polyester resin, alkyd resin, polyvinyl chloride resin, rosin-modified maleic acid resin, ketone resin, cyclized rubber, chlorinated rubber, butyral, petroleum resin, and the like. The resin can be used alone or in combination of 2 or more. The content of the resin for combination is preferably 1 to 50% by mass, and more preferably 2 to 40% by mass, based on the total mass of the ink.

Examples of the coloring pigment used in the liquid ink composition of the present invention include organic and inorganic pigments and dyes used in general inks, paints, recording agents, and the like. Examples of the organic pigment include azo-based, phthalocyanine-based, anthraquinone-based, perylene-based, perillylone (perinone) -based, quinacridone-based, thioindigo-based, dioxazine-based, isoindolinone-based, quinophthalone-based, azomethine-based, diketopyrrolopyrrole-based, isoindoline-based pigments. Copper phthalocyanine is preferably used as the blue ink, and c.i. pigment No Yellow 83 is preferably used as the clear Yellow ink from the viewpoints of cost and light resistance.

Examples of the inorganic pigment include carbon black, titanium oxide, zinc sulfide, barium sulfate, calcium carbonate, chromium oxide, silica, red iron oxide, aluminum, Mica (Mica), and the like. Further, a bright pigment (METASHINE; Japan plate Nitri K.K.) obtained by further coating a base material of a glass flake or a bulk flake with a metal or a metal oxide can be used. In terms of cost and coloring power, titanium oxide is preferably used for the white ink, carbon black is preferably used for the black ink, aluminum is preferably used for the gold or silver ink, and Mica (Mica) is preferably used for the pearl ink. The aluminum is in the form of powder or paste, and is preferably used in the form of paste from the viewpoint of handling and safety, and the form of metal powder suspension or the form of non-metal powder suspension is suitably selected and used from the viewpoint of brightness and concentration.

In order to secure the concentration and coloring power of the ink, the colorant is preferably contained in a sufficient amount, that is, in a ratio of 1 to 50% by mass with respect to the total mass of the ink. Further, the coloring agent may be used alone or in combination of 2 or more.

The present invention may further contain a resin, a filler pigment, a pigment dispersant, a leveling agent, an antifoaming agent, a wax, a plasticizer, an infrared absorber, an ultraviolet absorber, an aromatic agent, a flame retardant, and the like, if necessary.

In order to stably disperse the colored pigment in the organic solvent, the resin alone can be dispersed, but a dispersant may be used in combination for further stable dispersion of the pigment. As the dispersant, anionic, nonionic, cationic, zwitterionic, and other surfactants can be used. Examples thereof include a comb-structured polymer compound obtained by adding a polyester to polyethyleneimine, and an alkylamine derivative of an α -olefin maleic acid polymer. Specific examples thereof include Solsperse series (ZENECA), Ajisper series (monosodium glutamate), and HOOGENOL series (King of flowers). Further, BYK series (BYK-Chemie), EFKA series (EFKA), and the like can be suitably used. The dispersant is preferably contained in the ink in an amount of 0.05% by mass or more based on the total mass of the ink from the viewpoint of storage stability of the ink, and is preferably contained in the ink in an amount of 5% by mass or less from the viewpoint of lamination suitability, and more preferably in an amount within a range of 0.1% by mass to 2% by mass.

The liquid ink composition of the present invention can be produced by dissolving and/or dispersing a resin, a coloring pigment, and the like in an organic solvent. Specifically, a pigment dispersion obtained by dispersing a pigment in an organic solvent with a urethane resin is produced, and if necessary, other compounds are added to the obtained pigment dispersion, whereby an ink can be produced.

The particle size distribution of the pigment in the pigment dispersion can be adjusted by appropriately adjusting the size of the pulverization medium of the dispersing machine, the filling rate of the pulverization medium, the dispersion treatment time, the ejection speed of the pigment dispersion, the viscosity of the pigment dispersion, and the like. As the dispersing machine, for example, a commonly used roll mill, ball mill, pebble mill, attritor, sand mill, or the like can be used.

If the ink contains air bubbles, unintended coarse particles, or the like, the quality of the printed matter is degraded, and therefore, it is preferable to remove the ink by filtration or the like. The filter may be a conventionally known filter.

The viscosity of the ink produced by the above method is preferably 10mPa · s or more from the viewpoint of preventing sedimentation of the pigment and dispersing the pigment appropriately, and is preferably 1000mPa · s or less from the viewpoint of workability at the time of ink production and printing. The viscosity is measured at 25 ℃ with a B-type viscometer manufactured by Tokimec corporation.

The viscosity of the ink can be adjusted by appropriately selecting the kind and amount of the raw material used, for example, a urethane resin, a colorant, an organic solvent, and the like. Further, the viscosity of the ink can be adjusted by adjusting the particle size and particle size distribution of the pigment in the ink.

The color tone of the liquid ink composition of the present invention includes 5 colors of yellow, red, blue, black and white as process basic colors, and 3 colors of red (orange), grass (green) and violet as process control color ranges, depending on the type of pigment used. Further, as the base color, transparent yellow, peony, vermilion, tea, gold, silver, pearl, a nearly transparent medium for color density adjustment (containing a filler pigment as needed), and the like can be prepared. The boiling treatment ink is appropriately selected in consideration of migration property and heat resistance of the pigment. The base ink of each color tone is diluted with a diluting solvent to a viscosity and a density suitable for gravure printing or flexographic printing, and can be supplied to each printing unit individually or in a mixed manner.

The liquid ink composition of the present invention is printed or coated on various film or sheet-like substrates by using the above-described printing method, and is dried and fixed by drying in an oven, whereby a printed material or a coated material can be obtained. Examples of the film or sheet base material include polyolefin resins such AS polyethylene and polypropylene, polyester resins such AS polyethylene terephthalate, polycarbonate and polylactic acid, polystyrene resins such AS polystyrene, AS resins and ABS resins, nylon, polyamide, polyvinyl chloride, polyvinylidene chloride, cellophane, paper, aluminum and the like, and composite materials thereof.

The substrate may be subjected to a treatment of coating the surface with a metal oxide or the like by vapor deposition and/or a treatment of coating the surface with polyvinyl alcohol or the like, and may be further subjected to a surface treatment such as corona treatment.

Further, a laminated laminate using the printing ink of the present invention can be obtained by a known lamination step such as a general extrusion lamination (extrusion lamination) method of laminating a molten polyethylene resin on the printing surface of the printed matter via various anchor coating agents such as an imine based, isocyanate based, polybutadiene based, titanium based, etc., a dry lamination method of laminating a plastic film by applying an adhesive such as a urethane based adhesive on the printing surface, or a direct lamination method of laminating by directly pressing a molten polypropylene on the printing surface.

The liquid ink composition of the present invention can easily separate and recover the ester/alcohol component by recovering the solvent mixture generated in the printing and drying steps and the generated VOC gas as a liquid.

Examples

The present invention is further specifically illustrated by examples. Hereinafter, "part(s)" and "%" are based on mass.

The hydroxyl value is a value calculated by back titration of the remaining acid with a base when the hydroxyl group in the polyurethane resin is acetylated with an excessive amount of an acetylating agent, and expressed as mg of potassium hydroxide (KOH), and is a value based on jis k 0070.

The amine number is a value representing the number of mg of potassium hydroxide (KOH) equivalent to the equivalent of hydrochloric acid necessary for neutralizing the amino group contained in 1g of the polyurethane resin. As a method for measuring this, 30mL of neutral ethanol was added to a sample in which the amount of sample P g was precisely weighed and dissolved, and then the obtained solution was titrated with 0.2mol/L ethanolic hydrochloric acid solution (titer f). The end point was regarded as the point when the color of the solution changed from green to yellow, and the amine value was determined by the following (formula 2) using the titration amount (HmL) at that time.

The sample is the polyurethane resin solution obtained in each synthesis example, and is calculated by 30% in terms of the mass of the solid content.

Amine value (H.times.f.times.0.2X 56.108)/P/0.3 (mgKOH/g) formula (2)

(Synthesis example 1: preparation of polyurethane resin solution X1)

In a1 liter four-necked flask equipped with a stirrer, a thermometer, a serpentine reflux condenser and a nitrogen gas inlet, 228.71 parts of polyester polyol having a number average molecular weight of 3700 obtained from adipic acid and neopentyl glycol and 12.03 parts of polyethylene glycol having a number average molecular weight of 1000 (PEG #1000) were put, and the temperature was raised to 50 ℃ while stirring with introduction of nitrogen gas. Then, 42.98 parts of isophorone diisocyanate was charged and reacted at 90 ℃ until the NCO% remaining isocyanate group became 3.40%. After cooling, 152.77 parts of n-propyl acetate was added to obtain a urethane prepolymer solution having an isocyanate group at the terminal (A1).

Next, 19.44 parts of 1-amino-3-aminomethyl-3, 5, 5-trimethylcyclohexane, 2.48 parts of diethanolamine, 414.00 parts of n-propyl acetate, 143.00 parts of n-propanol, and 436.50 parts of a urethane prepolymer solution (a1) were put into a1 liter four-necked flask equipped with a stirrer, a thermometer, a serpentine reflux condenser and a nitrogen gas inlet, and reacted at 45 ℃ for 4 hours to obtain a polyurethane resin solution (X1) having a solid content of 30%, a weight-average molecular weight of 31600, an amine value of 3.2(mgKOH/g), a urea bond concentration of 0.8mmol/g, and a hydroxyl value of 7.4 (mgKOH/g).

(Synthesis example 2: preparation of polyurethane resin solution X2)

In a1 liter four-necked flask equipped with a stirrer, a thermometer, a serpentine reflux condenser and a nitrogen gas inlet, 725.00 parts of polyester polyol having a number average molecular weight of 3700 obtained from adipic acid and neopentyl glycol and 38.15 parts of polyethylene glycol having a number average molecular weight of 1000 (PEG #1000) were put, and the temperature was raised to 50 ℃ while stirring with introduction of nitrogen gas. Next, 124.01 parts of isophorone diisocyanate was charged and reacted at 90 ℃ until the NCO% as the residual ratio of isocyanate groups became 2.83%. After cooling, 477.70 parts of n-propyl acetate was added to obtain a urethane prepolymer solution having an isocyanate group at the terminal (A2).

Subsequently, 52.77 parts of 1-amino-3-aminomethyl-3, 5, 5-trimethylcyclohexane, 4.85 parts of diethanolamine, 1286 parts of n-propyl acetate, and 441 parts of n-propanol were placed in a 1-liter four-necked flask equipped with a stirrer, a thermometer, a serpentine reflux condenser, and a nitrogen gas inlet tube, 1364.86 parts of a urethane prepolymer solution (A2) was added, and the mixture was reacted at 45 ℃ for 4 hours to obtain a polyurethane resin solution (X2) having a solid content of 30%, a weight average molecular weight of 42500, an amine value of 3.2(mgKOH/g), a urea bond concentration of 0.7mmol/g, and a hydroxyl value of 4.7 (mgKOH/g).

(Synthesis example 3: preparation of polyurethane resin solution X3)

In a1 liter four-necked flask equipped with a stirrer, a thermometer, a serpentine reflux condenser and a nitrogen gas inlet, 228.71 parts of polyester polyol having a number average molecular weight of 3700 obtained from adipic acid and neopentyl glycol and 12.03 parts of polyethylene glycol having a number average molecular weight of 1000 (PEG #1000) were put, and the temperature was raised to 50 ℃ while stirring with introduction of nitrogen gas. Next, 35.32 parts of isophorone diisocyanate was charged and reacted at 90 ℃ until the NCO% remaining isocyanate group became 2.43%. After cooling, 148.65 parts of n-propyl acetate was added to obtain a urethane prepolymer solution having an isocyanate group at the terminal (A3).

Then, 14.23 parts of 1-amino-3-aminomethyl-3, 5, 5-trimethylcyclohexane, 1.50 parts of diethanolamine, 396.00 parts of n-propyl acetate, 136.00 parts of n-propanol, and 424.71 parts of the urethane prepolymer solution (A3) were put into a1 liter four-necked flask equipped with a stirrer, a thermometer, a serpentine reflux condenser, and a nitrogen gas inlet tube, and reacted at 45 ℃ for 4 hours to obtain a polyurethane resin solution (X3) having a solid content of 30%, a weight-average molecular weight of 47000, an amine value of 3.2(mgKOH/g), a urea bond concentration of 0.6mmol/g, and a hydroxyl value of 5.5 (mgKOH/g).

(Synthesis example 4: preparation of polyurethane resin solution X4)

264.2 parts of polyester polyol having a number average molecular weight of 5100 and obtained from adipic acid and 3-methyl-1, 5-pentanediol were put into a 1-liter four-necked flask equipped with a stirrer, a thermometer, a serpentine reflux condenser and a nitrogen introduction tube, and the temperature was raised to 50 ℃ while stirring with introduction of nitrogen. Then, 28.01 parts of isophorone diisocyanate was charged and reacted at 90 ℃ until the residual ratio of isocyanate groups, that is, NCO% became 1.99%. After cooling, 157.34 parts of n-propyl acetate was added to obtain a urethane prepolymer solution having an isocyanate group at the terminal (A4).

Then, 10.96 parts of 1-amino-3-aminomethyl-3, 5, 5-trimethylcyclohexane, 2.36 parts of diethanolamine, 413.00 parts of n-propyl acetate, 143.00 parts of n-propanol, and 449.55 parts of a urethane prepolymer solution (A4) were put into a1 liter four-necked flask equipped with a stirrer, a thermometer, a serpentine reflux condenser and a nitrogen gas inlet tube, and reacted at 45 ℃ for 4 hours to obtain a polyurethane resin solution (X4) having a solid content of 30%, a weight-average molecular weight of 41100, an amine value of 1.5(mgKHO/g), a urea bond concentration of 0.5mmol/g, and a hydroxyl value of 8.2 (mgKOH/g).

(Synthesis example 5: preparation of polyurethane resin solution X5)

264.2 parts of polyester polyol having a number average molecular weight of 5100 and obtained from adipic acid and 3-methyl-1, 5-pentanediol were put into a 1-liter four-necked flask equipped with a stirrer, a thermometer, a serpentine reflux condenser and a nitrogen introduction tube, and the temperature was raised to 50 ℃ while stirring with introduction of nitrogen. Then, 28.01 parts of isophorone diisocyanate was charged and reacted at 90 ℃ until the residual ratio of isocyanate groups, that is, NCO%, reached 1.98%. After cooling, 157.34 parts of n-propyl acetate was added to obtain a urethane prepolymer solution having an isocyanate group at the terminal (A5).

Then, 10.27 parts of 1-amino-3-aminomethyl-3, 5, 5-trimethylcyclohexane, 3.16 parts of diethanolamine, 414.00 parts of n-propyl acetate, 143.00 parts of n-propanol, and 449.55 parts of a urethane prepolymer solution (A5) were put into a1 liter four-necked flask equipped with a stirrer, a thermometer, a serpentine reflux condenser and a nitrogen gas inlet tube, and reacted at 45 ℃ for 4 hours to obtain a polyurethane resin solution (X5) having a solid content of 30%, a weight-average molecular weight of 62800, an amine value of 1.5(mgKOH/g), a urea bond concentration of 0.5mmol/g, and a hydroxyl value of 11.0 (mgKOH/g).

(Synthesis example 6: preparation of polyurethane resin solution X6)

Into a 1-liter four-necked flask equipped with a stirrer, a thermometer, a serpentine reflux condenser and a nitrogen gas inlet, 404.70 parts of polyester polyol having a number-average molecular weight of 5100, which was obtained from adipic acid and 3-methyl-1, 5-pentanediol, were charged, and the temperature was raised to 50 ℃ while stirring with introduction of nitrogen gas. Next, 37.37 parts of isophorone diisocyanate was charged and reacted at 90 ℃ until the NCO% as the residual ratio of isocyanate groups became 1.62%. After cooling, 238.04 parts of n-propyl acetate was added to obtain a urethane prepolymer solution having an isocyanate group at the terminal (A6).

Then, 14.15 parts of 1-amino-3-aminomethyl-3, 5, 5-trimethylcyclohexane, 2.88 parts of diethanolamine, 620.00 parts of n-propyl acetate, 215.00 parts of n-propanol, and 680.11 parts of a urethane prepolymer solution (A6) were put into a1 liter four-necked flask equipped with a stirrer, a thermometer, a serpentine reflux condenser and a nitrogen gas inlet, and reacted at 45 ℃ for 4 hours to obtain a polyurethane resin solution (X6) having a solid content of 30%, a weight-average molecular weight of 31600, an amine value of 2.0(mgKOH/g), a urea bond concentration of 0.3mmol/g, and a hydroxyl value of 6.7 (mgKOH/g).

(Synthesis example 7: preparation of polyurethane resin solution X7)

Into a 1-liter four-necked flask equipped with a stirrer, a thermometer, a serpentine reflux condenser and a nitrogen gas inlet, 264.20 parts of polyester polyol having a number-average molecular weight of 5100, which was obtained from adipic acid and 3-methyl-1, 5-pentanediol, were charged, and the temperature was raised to 50 ℃ while stirring with introduction of nitrogen gas. Then, 28.01 parts of isophorone diisocyanate was charged and reacted at 90 ℃ until the residual ratio of isocyanate groups, that is, NCO% became 1.99%. After cooling, 157.34 parts of n-propyl acetate was added to obtain a urethane prepolymer solution having an isocyanate group at the terminal (B2).

Then, 10.96 parts of 1-amino-3-aminomethyl-3, 5, 5-trimethylcyclohexane, 1.37 parts of monoethanolamine, 411.00 parts of n-propyl acetate, 142.00 parts of n-propanol, and 449.55 parts of a urethane prepolymer solution (B2) were put into a 1-liter four-necked flask equipped with a stirrer, a thermometer, a serpentine reflux condenser, and a nitrogen gas inlet, and reacted at 45 ℃ for 4 hours to obtain a polyurethane resin solution (X7) having a solid content of 30%, a weight-average molecular weight of 48000, an amine value of 1.5(mgKOH/g), a urea bond concentration of 0.5mmol/g, and a hydroxyl value of 4.1 (mgKOH/g).

(Synthesis comparative example 1: preparation of polyurethane resin solution Y1)

In a1 liter four-necked flask equipped with a stirrer, a thermometer, a serpentine reflux condenser and a nitrogen gas inlet, 228.71 parts of polyester polyol having a number average molecular weight of 3700 obtained from adipic acid and neopentyl glycol and 12.03 parts of polyethylene glycol having a number average molecular weight of 1000 (PEG #1000) were put, and the temperature was raised to 50 ℃ while stirring with introduction of nitrogen gas. Next, 46.81 parts of isophorone diisocyanate was charged and reacted at 90 ℃ until the NCO% remaining isocyanate group became 3.60%. After cooling, 154.84 parts of n-propyl acetate was added to obtain a urethane prepolymer solution having an isocyanate group at the terminal (B1).

Subsequently, 20.89 parts of 1-amino-3-aminomethyl-3, 5, 5-trimethylcyclohexane, 2.51 parts of diethanolamine, 426.00 parts of n-propyl acetate, 145.00 parts of n-propanol, and 442.39 parts of a urethane prepolymer solution (B1) were put into a1 liter four-necked flask equipped with a stirrer, a thermometer, a serpentine reflux condenser and a nitrogen gas inlet, and reacted at 45 ℃ for 4 hours to obtain a polyurethane resin solution (Y1) having a solid content of 30%, a weight-average molecular weight of 31800, an amine value of 3.2(mgKOH/g), a urea bond concentration of 0.9mmol/g, and a hydroxyl value of 7.4 (mgKOH/g).

(Synthesis comparative example 2: preparation of polyurethane resin solution Y2)

Into a 1-liter four-necked flask equipped with a stirrer, a thermometer, a serpentine reflux condenser and a nitrogen gas inlet tube, 107.41 parts of polyester polyol having a number average molecular weight of 2000, which is obtained from adipic acid and propylene glycol, and 107.41 parts of polypropylene glycol (PPG #1000) having a number average molecular weight of 1000 were charged, and the temperature was raised to 50 ℃ while stirring with introduction of nitrogen gas. Then, 56.11 parts of toluene diisocyanate was charged and reacted at 90 ℃ until the NCO% as the residual ratio of isocyanate groups became 4.80%. After cooling, 82.5 parts of ethyl acetate was added to obtain a urethane prepolymer solution having an isocyanate group at the terminal (B3).

Then, 27.67 parts of 1-amino-3-aminomethyl-3, 5, 5-trimethylcyclohexane, 1.41 parts of diethanolamine, 327.47 parts of ethyl acetate, 290.00 parts of isopropyl alcohol, and 416.82 parts of a urethane prepolymer solution (B3) were put into a1 liter four-neck flask equipped with a stirrer, a thermometer, a serpentine reflux condenser and a nitrogen gas inlet tube, and reacted at 45 ℃ for 4 hours to obtain a polyurethane resin solution (Y2) having a solid content of 30%, a weight-average molecular weight of 32400, an amine value of 4.5(mgKOH/g), a urea bond concentration of 1.1mmol/g, and a hydroxyl value of 5.0 (mgKOH/g).

(Synthesis comparative example 3: preparation of polyurethane resin solution Y3)

In a1 liter four-necked flask equipped with a stirrer, a thermometer, a serpentine reflux condenser and a nitrogen gas inlet, 228.71 parts of polyester polyol having a number average molecular weight of 3700 obtained from adipic acid and neopentyl glycol and 12.03 parts of polyethylene glycol having a number average molecular weight of 1000 (PEG #1000) were put, and the temperature was raised to 50 ℃ while stirring with introduction of nitrogen gas. Next, 41.46 parts of isophorone diisocyanate was charged and reacted at 90 ℃ until the NCO% remaining isocyanate group became 2.50%. After cooling, 151.96 parts of n-propyl acetate was added to obtain a urethane prepolymer solution having an isocyanate group at the terminal (B4).

Subsequently, 18.57 parts of 1-amino-3-aminomethyl-3, 5, 5-trimethylcyclohexane, 3.99 parts of diethanolamine, 417.00 parts of n-propyl acetate, 142.00 parts of n-propanol, and 434.17 parts of a urethane prepolymer solution (B4) were put into a1 liter four-necked flask equipped with a stirrer, a thermometer, a serpentine reflux condenser and a nitrogen gas inlet tube, and reacted at 45 ℃ for 4 hours to obtain a polyurethane resin solution (Y3) having a solid content of 30%, a weight-average molecular weight of 32500, an amine value of 3.2(mgKOH/g), a urea bond concentration of 0.8mmol/g, and a hydroxyl value of 12.0 (mgKOH/g).

Comparative Synthesis example 4 preparation of polyurethane resin solution Y4

In a1 liter four-necked flask equipped with a stirrer, a thermometer, a serpentine reflux condenser and a nitrogen gas inlet, 228.71 parts of polyester polyol having a number average molecular weight of 3700 obtained from adipic acid and neopentyl glycol and 12.03 parts of polyethylene glycol having a number average molecular weight of 1000 (PEG #1000) were put, and the temperature was raised to 50 ℃ while stirring with introduction of nitrogen gas. Next, 25.51 parts of isophorone diisocyanate was charged and reacted at 90 ℃ until the NCO% as the residual ratio of isocyanate groups became 1.20%. After cooling, 143.37 parts of n-propyl acetate was added to obtain a urethane prepolymer solution having an isocyanate group at the terminal (B4).

Subsequently, 6.35 parts of 1-amino-3-aminomethyl-3, 5, 5-trimethylcyclohexane, 1.07 parts of diethanolamine, 367.00 parts of n-propyl acetate, 128.00 parts of n-propanol, and 409.62 parts of the urethane prepolymer solution (B4) were put into a1 liter four-necked flask equipped with a stirrer, a thermometer, a serpentine reflux condenser and a nitrogen gas inlet tube, and reacted at 45 ℃ for 4 hours to obtain a polyurethane resin solution (Y4) having a solid content of 30%, a weight-average molecular weight of 71000, an amine value of 0.7(mgKOH/g), a urea bond concentration of 0.3mmol/g, and a hydroxyl value of 3.6 (mgKOH/g).

Comparative Synthesis example 5 preparation of polyurethane resin solution Y5

In a1 liter four-necked flask equipped with a stirrer, a thermometer, a serpentine reflux condenser and a nitrogen gas inlet, 228.71 parts of polyester polyol having a number average molecular weight of 3700 obtained from adipic acid and neopentyl glycol and 12.03 parts of polyethylene glycol having a number average molecular weight of 1000 (PEG #1000) were put, and the temperature was raised to 50 ℃ while stirring with introduction of nitrogen gas. Next, 25.51 parts of isophorone diisocyanate was charged and reacted at 90 ℃ until the NCO% as the residual ratio of isocyanate groups became 1.20%. After cooling, 143.37 parts of n-propyl acetate was added to obtain a urethane prepolymer solution having an isocyanate group at the terminal (B5).

Then, 5.35 parts of 1-amino-3-aminomethyl-3, 5, 5-trimethylcyclohexane, 0.30 part of diethanolamine, 364.00 parts of n-propyl acetate, 127.00 parts of n-propanol, and 409.62 parts of a urethane prepolymer solution (B4) were put into a1 liter four-necked flask equipped with a stirrer, a thermometer, a serpentine reflux condenser and a nitrogen gas inlet tube, and reacted at 45 ℃ for 4 hours to obtain a polyurethane resin solution (Y5) having a solid content of 30%, a weight-average molecular weight of 25000, an amine value of 3.7(mgKOH/g), a urea bond concentration of 0.3mmol/g, and a hydroxyl value of 12.9 (mgKOH/g).

(preparation of vinyl chloride-vinyl acetate copolymer resin solution)

A vinyl chloride-vinyl acetate copolymer resin having a hydroxyl group (resin monomer composition in mass% of vinyl chloride/vinyl acetate/vinyl alcohol: 92/3/5, hydroxyl value (mgKOH) ═ 64) was used in combination with a polyurethane resin to prepare a 15% solution using n-propyl acetate, and the solution was used as a vinyl chloride-vinyl acetate resin solution (V1).

(example 1)

10.00 parts of Fastogen Blue FA5375, 30.00 parts of a 15% solution (V1) of n-propyl acetate of a vinyl chloride-vinyl acetate copolymer resin, and 10.00 parts of an n-propyl acetate/n-propanol mixed solvent (weight ratio 90/10) were mixed and stirred, and kneaded by a paint mixer, and then 130.00 parts of a polyurethane resin composition X and 20.00 parts of an n-propyl acetate/n-propanol mixed solvent (weight ratio 90/10) were mixed and stirred, to obtain a Blue ink composition. It was diluted with n-propyl acetate and adjusted to 16 seconds at 25 ℃ in zeiencup #3 (manufactured by clutching company).

The inks of examples 2 to 7 were prepared by the same procedure as in example 1 based on the formulation shown in table 3, the inks of examples 8 to 14 were prepared based on the formulation shown in table 4, and the inks of comparative examples 1, 3 to 5 were prepared based on the formulation shown in table 5. Examples 8 to 14 and comparative example 2 were diluted with ethyl acetate/isopropyl alcohol (50/50 mass ratio) and further with ethyl acetate, and were adjusted to 25 ℃ for 16 seconds in zehn cup #3 (manufactured by clutching company) in the same manner as in example 1. The ratio (mass ratio) of the ester-based solvent to the alcohol-based solvent in the final blue ink is shown in tables 3 to 5.

The obtained liquid blue ink was printed using a gravure printer (manufactured by DIC Engineering) equipped with a laser gravure having a plate depth of 35 μm, and the highlight transferability, the measurement of the lamination strength, and the solvent recovery efficiency of the printed matter were evaluated. The evaluation results are shown in tables 3 to 5. The evaluation was performed according to the following method.

(1) High light transferability

Biaxially oriented polypropylene (OPP) film P2161 (thickness: 20 μm) manufactured by Toyo Boseki Kabushiki Kaisha was printed, and the respective high light transfer properties immediately after the start of printing, 2 hours after idling, and 4 hours after idling were visually evaluated. The evaluation criteria were the following 5 grades.

(evaluation criteria)

5: almost no "whitish" is seen in the gradation portion "

4: slight "whiting" is seen in the gradation portion "

3: the whitening can be seen in the gradual change part "

2: the whitening is obvious in the gradual change part

1: a great deal of whitish is seen in the gradual change part "

(2) Measurement of lamination Strength

The obtained liquid blue ink was printed on the treated surface of a biaxially stretched polyester film (PET film with a thickness of 12 μm E-5100 manufactured by Toyo Seiki Kagaku K.K.) having a corona-treated single surface using a gravure printing machine (manufactured by DIC Engineering Co., Ltd.) equipped with a laser gravure plate having a plate depth of 25 μm.

On the printed product of the biaxially stretched polyester film thus obtained, an aluminum foil and an unstretched polypropylene film (hereinafter referred to as R-CPP: ZK-7550 μm manufactured by Toray synthetic film Co., Ltd.) were laminated by a dry laminating machine (DIC Engineering) using a urethane-based dry laminating adhesive DICdry LX-703VL/KR-90 (DIC) and aged at 40 ℃ for 3 days to obtain a laminate.

The obtained laminate was formed into a 120mm × 120 mm-sized bag, and vinegar, salad oil, and meat sauce were blended in a weight ratio of 1: 1: 1, the resulting simulated food 70g was subjected to filling and sealing. The bag was subjected to a steaming treatment at 135 ℃ for 30 minutes, the contents were taken out, the bag was washed with water, and then the bag was cut into a width of 15mm, and a 180-degree T-peel test was performed at a tensile rate of 300 mm/minute.

The laminate thus produced was a PET substrate (F)/printing ink layer (I)/adhesive layer (Ad 1)/aluminum foil (AL)/adhesive (Ad2)/R-CPP film in this order from the PET film side of the substrate.

A biaxially stretched polyester film (PET film: E-5100, Toyo Seiki Kagaku K.K.) was used, and the thickness was 12 μm.

The larger the value, the higher the intensity.

The evaluation results in tables 3 to 5 are abbreviated as follows.

F Cut: the abbreviation for FILM CUT indicates that the FILM broke before the laminate peeled off in the assay. The higher the lamination strength, the more excellent the film strength.

I/AL: the adhesive layer (Ad1) between the printing ink layer (I) and the aluminum foil (AL) was peeled off in the measured value shown.

F/I: peeling occurred between the PET substrate (F)/the printing ink layer (I) in the measured value shown.

(3) Solvent recovery efficiency

A solvent recovery tester (manufactured by Kureha Engineering) was connected to the exhaust port of a dryer of a gravure printing press (manufactured by DIC Engineering Co., Ltd.) through a pipe. Printing was performed using a gravure plate having a plate depth of 35 μm under the same conditions as in the high light transfer test (1) above, and the pH of the solvent recovered by the recovery device after 4 hours of idle running was measured. For the measurement of pH, 100g of the recovered solvent was put into a separatory funnel to which 100g of water was added, and after shaking for 2 minutes, the water was separated and the pH of the water was measured by a pH meter. The evaluation criteria were set to the following 3-level.

(evaluation criteria)

O: above pH5, less than pH 8.

And (delta): above pH3, less than pH 5.

X: less than pH 3.

[ Table 1]

[ Table 2]

[ Table 3]

[ Table 4]

[ Table 5]

From the above results, it is clear that: the liquid ink composition of the present invention has a small elution of a dissolved component of the pigment in the solvent, and therefore, has excellent recovery efficiency of the volatile solvent, and also has excellent ink transferability and lamination strength.

Industrial applicability

The liquid ink composition of the present invention can be widely used for industrial products such as food packaging materials, sanitary wares, cosmetics, and electronic components by being prepared as gravure ink or flexo ink suitable for solvent recovery and reuse, which facilitates recovery of the solvent used.

Claims (8)

1. A gravure ink for flexible packaging lamination comprising a polyurethane resin A and an organic solvent B, wherein,

the polyurethane resin A takes polyester polyol and/or polyether polyol, diethanol amine and isophorone diisocyanate as reaction raw materials, the weight average molecular weight of the polyurethane resin A is in the range of 30000-70000, the urea bond concentration is less than 0.8mmol/g, and the hydroxyl value is 0.5 mgKOH/g-10.0 mgKOH/g,

the organic solvent B comprises n-propyl acetate or a mixed solvent of ethyl acetate/n-propanol or isopropanol, and the organic solvent B contains an ester solvent in an amount of 90 mass% or more of the total amount of the organic solvent B and an alcohol solvent in an amount of 0.1 mass% or more of the total amount of the organic solvent B.

2. The gravure ink for flexible packaging lamination according to claim 1, wherein the polyester polyol has a number average molecular weight of 3000 to 7000.

3. The gravure ink for flexible packaging lamination according to claim 1 or 2, which further contains a vinyl chloride-vinyl acetate copolymer resin C having a hydroxyl group.

4. The gravure ink for flexible packaging lamination according to claim 3, wherein the hydroxyl value of the vinyl chloride-vinyl acetate copolymer resin C having a hydroxyl group is 50mgKOH/g to 200mgKOH/g, and the content ratio of the vinyl chloride component in the copolymer resin C is 80% by mass to 95% by mass.

5. The gravure ink for flexible packaging lamination according to claim 1 or 2, wherein the amine value of the polyurethane resin a is 6.5mgKOH/g or less.

6. A printed matter obtained by printing the gravure ink for flexible packaging laminate according to any one of claims 1 to 5 on a film.

7. The printed matter according to claim 6, wherein the film is any one selected from the group consisting of a polyolefin-based resin, a polyester-based resin, a polystyrene-based resin, a polyamide, polyvinyl chloride, polyvinylidene chloride, and cellophane.

8. A laminated laminate having a printed layer printed with the gravure ink for flexible packaging lamination according to any one of claims 1 to 5.