JP7697178B2 - Method for producing ink composition for gravure printing - Google Patents

Description

The present invention relates to a method for producing an ink composition for gravure printing.

As described in Patent Document 1, it is known that urethane prepolymer is chain-elongated and the reaction is terminated, and then acetone is directly added to the resulting polyurethane resin solution to react a ketone compound with the amino group at the end of the polyurethane resin, thereby carrying out ketiminization. The ketiminized polyurethane resin obtained by such a synthesis method for ketiminized polyurethane resin is said to have reduced odor and excellent viscosity stability.
The ketiminated polyurethane resin obtained by this synthesis method has a reduced irritating odor due to acetone, but the low molecular weight chain extenders and reaction terminators present in the resin composition are also ketiminated.
As a result, a different odor is generated due to the ketimine-containing low-molecular-weight chain extender and reaction terminator, and ultimately, the odor of the resin composition as a whole cannot be sufficiently suppressed.
Furthermore, suppressing the molecular weight reduction of polyurethane during storage improves viscosity stability, but residual ketimine-formed low molecular weight chain extenders and reaction terminators that cannot be completely removed cause a problem of reduced stability over time of ink compositions, paints, etc.
In addition, in polyurethane resins obtained by conventionally known production methods, the smaller the molecular weight, the more non-uniform the reaction is, resulting in the presence of unreacted low molecular weight chain extenders. As a result, printing ink compositions and printed matter using polyurethane resins have an amine odor, and when such polyurethane resins are used and a pigment is further dispersed, the dispersibility tends to decrease.

In addition, as described in Patent Documents 2 and 3, it is known that a ketimine compound obtained from a diamine and a ketone is reacted with a urethane prepolymer in an aqueous solvent to obtain a polyurethane polyurea resin powder for slush molding or the like.
In particular, Patent Document 2 describes chain extension of a urethane prepolymer with a di-condensate of a ketone in the presence of water and a dispersion stabilizer.

JP 2017-2184 A JP 2012-251010 A JP 2011-208128 A

The problem that the present invention aims to solve is to provide a method for producing an ink composition for gravure printing that improves the stability over time of the ink composition and at the same time prevents the ink composition itself and the printed area from retaining an odor after printing.

The present inventors have discovered that the above problems can be solved by employing a specific method for producing an ink composition for gravure printing.
That is, the present invention provides
1. A method for producing an ink composition for gravure printing, comprising the following steps A to E:
A. A process for synthesizing a urethane prepolymer from an organic diisocyanate compound and a polymeric diol compound;
B. A step of mixing a urethane prepolymer with an organic solvent to obtain a urethane prepolymer solution;
C. A step of adding and mixing a compound in which an amino group of a polyamine compound is ketiminated with a ketone compound;
D. A process of adding water under the following conditions, followed by chain extension and/or reaction termination to obtain a polyurethane polyurea resin solution for gravure printing;
Condition: Within the range in which the polyurethane polyurea resin for gravure printing obtained by the method for producing the polyurethane polyurea resin for gravure printing does not precipitate
E. Step of adding a colorant to the polyurethane polyurea resin solution for gravure printing 2. The method for producing an ink composition for gravure printing according to 1, wherein the organic diisocyanate compound and the polymer diol are used in a ratio such that the equivalent ratio of isocyanate groups to hydroxyl groups (isocyanate index) is NCO groups/OH groups=1.2 to 3.0.
3. The method for producing an ink composition for gravure printing according to 1 or 2, wherein the organic solvent is a mixed solvent of an ester-based organic solvent and an alcohol-based organic solvent, or an ester-based organic solvent.
4. The method for producing an ink composition for gravure printing according to any one of 1 to 3, wherein the ketiminated compound is a compound in which an amino group of a polyamine compound is ketiminated with one or more ketone compounds selected from acetone, diethyl ketone, methyl ethyl ketone and diacetone alcohol.

According to the present invention, it is possible to obtain an ink composition for gravure printing that has excellent stability over time when made into an ink composition, does not generate odors specific to amines and ketimines, and the resulting printed matter does not have the odors specific to amines and ketimines.

The method for producing the ink composition for gravure printing of the present invention will be described below.
A method for producing an ink composition for gravure printing, comprising the following steps A to E:
A. A process for synthesizing a urethane prepolymer from an organic diisocyanate compound and a polymeric diol compound;
B. A step of mixing a urethane prepolymer with an organic solvent to obtain a urethane prepolymer solution;
C. A step of mixing a urethane prepolymer solution with a compound in which an amino group of a polyamine compound is ketiminated with a ketone compound;
D. A process of adding water under the following conditions, followed by chain extension and/or reaction termination to obtain a polyurethane polyurea resin solution for gravure printing;
Condition: Within the range in which the polyurethane polyurea resin for gravure printing obtained by the method for producing the polyurethane polyurea resin for gravure printing does not precipitate
E. Adding a colorant to the polyurethane polyurea resin solution for gravure printing;

<A. Step of synthesizing urethane prepolymer from organic diisocyanate compound and polymeric diol compound>
The process for synthesizing the urethane prepolymer comprises a process for reacting the following organic diisocyanate compound with a polymeric diol compound.
(Organic diisocyanate compounds)
Examples of the organic diisocyanate compound include aromatic diisocyanate compounds such as 1,3- and/or 1,4-phenylene diisocyanate, 4,4-diisocyanatobiphenyl, 3,3-dimethyl-4,4-diisocyanatobiphenyl, and tolylene diisocyanate, dicyclohexylmethane 4,4'-diisocyanate, 1,4-cyclohexane diisocyanate, cyclohexylene diisocyanate, dicyclohexylmethane-4,4-diisocyanate (hydrogenated MDI), methylcyclohexylene diisocyanate (hydrogenated TDI), and isophorone diisocyanate. Examples of the organic diisocyanate compounds include alicyclic diisocyanate compounds such as hexamethylene diisocyanate (HDI), ethylene diisocyanate, tetramethylene diisocyanate, dodecamethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, and aliphatic diisocyanate compounds such as m- and/or p-xylylene diisocyanate (XDI) and α,α,α',α'-tetramethylxylylene diisocyanate. These organic diisocyanate compounds can be used alone or in combination of two or more. Among these, alicyclic diisocyanates, aliphatic diisocyanates, and araliphatic diisocyanates are more preferred.

(Polymer diol compound)
Examples of the polymer diol compound include polyester diols obtained by a condensation reaction of one or more dibasic acids such as adipic acid, sebacic acid, phthalic anhydride, etc. with one or more glycols such as ethylene glycol, propylene glycol, 1,4-butanediol, neopentyl glycol, 3-methyl-1,5-pentanediol, etc., polyester diol compounds such as polycaprolactone diols, and further polyalkylene glycols such as polyethylene glycol, polypropylene glycol, and polyether diol compounds such as alkylene oxide adducts of bisphenol A with ethylene oxide, propylene oxide, etc. These polymer diol compounds can be used alone or in combination of two or more. Among these, 3-methyl-1,5-pentylene adipate diol having a number average molecular weight of 1,000 to 8,000 obtained by condensation reaction of adipic acid and 3-methyl-1,5-pentanediol is preferred, and 3-methyl-1,5-pentylene adipate diol having a number average molecular weight of 1,000 to 4,000 is more preferred.

(Bio-polyester diol compound)
When environmental considerations are taken into account, a biopolyester polyol is used as the polymer diol compound.
The biopolyester diol compound is preferably a biopolyester polyol compound obtained by reacting a short-chain diol component having 2 to 4 carbon atoms with a carboxylic acid component. It is more preferable that at least one of the short-chain diol component and the carboxylic acid component is derived from a plant, or that both are derived from a plant.

The plant-derived short-chain diol component having 2 to 4 carbon atoms is not particularly limited. As an example, the short-chain diol component may be 1,3-propanediol, 1,4-butanediol, ethylene glycol, etc., which are obtained from plant raw materials by the following method. These may be used in combination.

1,3-propanediol can be produced from glycerol via 3-hydroxypropylaldehyde (HPA) by a fermentation method in which glucose is obtained by decomposing plant resources (such as corn, etc.). 1,3-propanediol compounds produced by biomethods such as the above-mentioned fermentation method are safer than 1,3-propanediol compounds produced by the EO production method, because useful by-products such as lactic acid can be obtained, and the production costs can be kept low. 1,4-butanediol can be produced by producing glycol from plant resources, fermenting it, obtaining succinic acid, and hydrogenating it. Ethylene glycol can also be produced from bioethanol obtained by a conventional method via ethylene.

The plant-derived carboxylic acid component is not particularly limited. Examples of the carboxylic acid component include sebacic acid, succinic acid, lactic acid, glutaric acid, and dimer acid. These may be used in combination.
Among these, the carboxylic acid component preferably contains at least one selected from the group consisting of sebacic acid, succinic acid, and dimer acid. In addition, 0.05 to 0.5 parts by mass of malic acid may be contained per 100 parts by mass of sebacic acid.

From an environmental perspective, the biomass polyurethane prepolymer obtained from these plant-derived components preferably accounts for 10% by mass or more, and more preferably 40% by mass or more, calculated as solid content, of the total polyurethane prepolymer obtained.

(Other diol compounds)
In addition to the above-mentioned high molecular weight diol compounds, alkanediols such as 1,4-pentanediol, 2,5-hexanediol, and 3-methyl-1,5-pentanediol, and low molecular weight diol compounds such as ethylene glycol, propylene glycol, 1,4-butanediol, and 1,3-butanediol can be used alone or in combination of two or more kinds.

When the organic diisocyanate compound and the polymer diol compound are reacted, the use ratio of each is preferably 1.2:1 to 3.0:1, more preferably 1.3:1 to 2.0:1, in terms of the equivalent ratio of isocyanate group:hydroxyl group (isocyanate index).
If the isocyanate index is less than 1.2, the polyurethane polyurea resin tends to be flexible, and there is a possibility that the blocking resistance and the like will be low when the ink composition is printed. In this case, it may be necessary to use the ink composition in combination with another hard resin.

(Reaction of organic diisocyanate compound with polymeric diol compound)
A catalyst can be used in the reaction between the organic diisocyanate compound and the polymeric diol compound.
Among these, it is preferable to use an organometallic compound. Examples of such an organometallic compound include titanium compounds such as dibutyltitanium dichloride, tetrabutyltitanium, and butoxytitanium trichloride, dibutyltin sulfide, tributyltin sulfide, tributyltin oxide, dibutyltin dichloride, dibutyltin oxide, dibutyltin dibromide, dibutyltin dimaleate, dibutyltin dilaurate, dibutyltin diacetate, dioctyltin dilaurate, and tributyltin. Examples of suitable lead compounds include tin compounds such as lead acetate, tributyltin chloride, triethyltin ethoxide, tributyltin ethoxide, dioctyltin oxide, tributyltin trichloroacetate, and tin 2-ethylhexanoate, lead compounds such as lead oleate, lead 2-ethylhexanoate, lead benzoate, and lead naphthenate, and further compounds such as iron 2-ethylhexanoate, iron acetylacetonate, cobalt benzoate, cobalt 2-ethylhexanoate, zinc naphthenate, zinc 2-ethylhexanoate, and zirconium naphthenate. Among these, titanium compounds such as tetrabutyl titanate are preferred.
Also, tertiary amine compounds can be used, such as triethylamine, triethylenediamine, 1,4-diazabicyclo(2,2,2)octane, and 1,8-diazabicyclo(5,4,0)-undecene-7 (DBU).

<B. Step of stirring and mixing the urethane prepolymer and the organic solvent to obtain a urethane prepolymer solution>
(Organic solvent)
The organic solvent used in this step is not particularly limited, but from the viewpoint of environmental consideration, it is preferable that it does not contain an aromatic hydrocarbon-based organic solvent. Examples of such solvents include alcohol-based organic solvents such as methanol, ethanol, n-propanol, isopropanol, and butanol; ketone-based organic solvents such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; ester-based organic solvents such as methyl acetate, ethyl acetate, propyl acetate, and butyl acetate; aliphatic hydrocarbon-based organic solvents such as n-hexane, n-heptane, and n-octane; and alicyclic hydrocarbon-based organic solvents such as cyclohexane, methylcyclohexane, ethylcyclohexane, cycloheptane, and cyclooctane. At least one of the solvents may be used, and two or more of them may be used in combination, taking into consideration the solubility and drying properties of the binder resin. However, from the viewpoint of further environmental consideration, it is preferable to suppress the use of ketone-based organic solvents among the solvents. More preferred solvents are mixed solvents of ester-based solvents and alcohol-based solvents or ester-based organic solvents. When using a mixed solvent of an ester-based solvent and an alcohol-based solvent, a mixed ester-based solvent obtained by mixing ethyl acetate and propyl acetate in a ratio of ethyl acetate:propyl acetate=1 to 4:1 on a mass basis, and a solvent obtained by mixing isopropyl alcohol in a ratio of mixed ester-based solvent:isopropyl alcohol=1 to 5:1 are more preferred.

(mixture)
Using a known stirring device, the organic solvent is added to and mixed with the urethane prepolymer under any stirring conditions to obtain a urethane prepolymer solution.

<C. Step of stirring and mixing the urethane prepolymer solution and the compound obtained by ketiminizing the amino group of the polyamine compound with a ketone compound>
(Polyamine Compound)
As the polyamine compound, known polyamine compounds used in polyurethane polyurea resins as binders for ink compositions can be used. For example, among polyamine compounds, aliphatic diamines such as ethylenediamine, propylenediamine, tetramethylenediamine, and hexamethylenediamine, alicyclic diamines such as isophoronediamine and 4,4'-dicyclohexylmethanediamine, aromatic diamines such as toluylenediamine, aromatic aliphatic diamines such as xylylenediamine, and diamines having a hydroxyl group such as N-(2-hydroxyethyl)ethylenediamine (aminoethylethanolamine), N-(2-hydroxyethyl)propylenediamine, and N,N'-di(2-hydroxyethyl)ethylenediamine can be mentioned.
Furthermore, polyamine compounds such as diethylenetriamine and triethylenetetramine can be used in combination within the range in which the polyurethane polyurea resin does not gel.

(A compound in which the amino group of a polyamine compound is ketiminated with a ketone compound)
A polyamine compound obtained by previously ketiminizing a polyamine compound with an excess amount of a ketone compound can be used as a chain extender and/or a reaction terminator. In particular, it is preferable to use isophoronediamine and/or N-(2-hydroxyethyl)ethylenediamine as the polyamine compound.
The polyamine compound ketiminated with a ketone compound has a structure in which the oxygen atom of the ketone compound is replaced by the nitrogen atom of the amino group of the polyamine compound. The ketone compound to be used is preferably acetone, diethyl ketone, methyl ethyl ketone, or diacetone alcohol.
In this ketiminization reaction, it is preferable not to use any solvent other than the ketone compound.
Incidentally, a polar organic solvent may be blended, rather than under solvent-free conditions, within a range that does not impede the subsequent chain extension/reaction termination reaction or the effect of the polyurethane polyurea resin having no odor.

(mixture)
The urethane prepolymer solution and a compound in which the amino group of a polyamine compound is ketiminated with a ketone compound under solvent-free conditions are mixed uniformly.

In this step, a reaction terminator can be added. Examples of reaction terminators include alkanolamines such as monoethanolamine and diethanolamine, monoamine compounds such as n-propylamine and n-butylamine, dialkylamines such as di-n-butylamine, and monoalcohol compounds such as ethanol. It is preferable to add a reaction terminator to the urethane prepolymer solution in step B between steps B and C described below and react it with part of the isocyanate in the urethane prepolymer.

<D. A process of adding water under the following conditions, and then carrying out chain extension and/or reaction termination to obtain a polyurethane polyurea resin solution for gravure printing>
(water)
The amount of water added in the chain extension and/or reaction termination step described below is preferably within a range in which the polyurethane polyurea resin for gravure printing obtained by the method for producing a polyurethane polyurea resin solution for gravure printing does not precipitate. Specifically, the amount of water is preferably 0.2 to 5.0 mass %, more preferably 0.4 to 1.5 mass %, based on the solid content of the polyurethane polyurea resin solution for gravure printing.

Chain Extension and/or Termination
Furthermore, after stirring and mixing the above-mentioned urethane prepolymer and an organic solvent, a compound in which the amino group of a polyamine compound is ketiminated under solvent-free conditions with a ketone compound is added, and water is added to the solution that has been uniformly stirred and mixed to carry out chain extension and/or reaction termination, thereby obtaining a polyurethane polyurea resin solution for gravure printing.
The amine value of the polyurethane polyurea resin for gravure printing obtained by this production method is preferably 1 to 10 mgKOH/g. If the amine value is less than 1 mgKOH/g, for example, when the composition is used as a gravure ink composition for lamination, the adhesion to the film may decrease and further the lamination suitability may decrease, and if the amine value exceeds 10 mgKOH/g, the blocking resistance may decrease. In the present invention, the amine value means the amine value per 1 g of solid content, and refers to the value measured by potentiometric titration using a 0.1 N aqueous hydrochloric acid solution (e.g. COMTITE (AUTO TITRATOR COM-900, BURET B-900, TITSTATION K-900), manufactured by Hiranuma Sangyo Co., Ltd.) and then converted into the equivalent amount of potassium hydroxide.

Between step B and step C, a step of adding a reaction terminator to the urethane prepolymer solution in step B to react with a part of the isocyanate of the urethane prepolymer may be included.
(Reaction stopper)
As the reaction terminator, known reaction terminators such as alkanolamines such as monoethanolamine and diethanolamine, monoamine compounds such as n-propylamine and n-butylamine, dialkylamines such as di-n-butylamine, and monoalcohol compounds such as ethanol can be used.

<E. Step of adding a colorant to a polyurethane polyurea resin solution for gravure printing>
In the present invention, a pigment and/or a dye can be used as the colorant. When the polyurethane polyurea resin solution for gravure printing is made into a gravure printing ink, the content of the colorant in the ink composition is preferably about 1 to 50% by mass.
(Pigment)
The pigments that can be used in the present invention are, for example, various inorganic pigments, organic pigments, or extender pigments that are generally used in printing inks. Examples of the inorganic pigments include color pigments such as titanium oxide, red iron oxide, antimony red, cadmium yellow, cobalt blue, Prussian blue, ultramarine blue, carbon black, and graphite, and examples of the extender pigments include silica particles, calcium carbonate, kaolin, clay, barium sulfate, aluminum hydroxide, and talc. Among these, it is preferable to use titanium oxide as a white pigment. Examples of the organic pigments include soluble azo pigments, insoluble azo pigments, azo lake pigments, condensed azo pigments, copper phthalocyanine pigments, and condensed polycyclic pigments.

(dye)
Dyes that can be used in the present invention include, for example, various dyes that are generally used in ink compositions for gravure printing, such as azo dyes, phthalocyanine dyes, anthraquinone dyes, perylene dyes, perinone dyes, quinacridone dyes, thioindigo dyes, dioxazine dyes, isoindolinone dyes, quinophthalone dyes, azomethine azo dyes, dicepyrrolopyrrole dyes, isoindoline dyes, and the like.

(Other compounds)
In the step of incorporating a colorant into a polyurethane polyurea resin solution for gravure printing, the solution may contain, as a binder resin, a vinyl chloride/vinyl acetate copolymer, a vinyl chloride/acrylic copolymer, or the like; as an adhesion improver, rosin and its derivatives, chlorinated polypropylene, or dammar resin; as an antiblocking agent, silica particles, polyethylene wax, fatty acid amide, cellulose acetate propionate resin, cellulose acetate butyrate resin, nitrocellulose, or the like; a pigment dispersant or dispersion aid; an organic solvent; water; an antistatic agent; and a silane coupling agent.

Vinyl chloride/vinyl acetate copolymer as binder resin The vinyl chloride/vinyl acetate copolymer contains, as essential components, vinyl chloride monomer and vinyl acetate monomer conventionally used in gravure ink compositions and the like, and, as necessary, fatty acid vinyl monomers such as vinyl propionate, vinyl monochloroacetate, vinyl versatate, vinyl laurate, vinyl stearate, vinyl benzoate, and monomers having functional groups such as hydroxyl groups, which are produced by conventional known methods.
Among them, in the organic solvent system of the environmentally friendly ink composition, a vinyl chloride/vinyl acetate copolymer having a hydroxyl group, preferably a vinyl chloride/vinyl acetate copolymer having a hydroxyl group with a hydroxyl value of 50 to 200 mgKOH/g, is suitable. Such a vinyl chloride/vinyl acetate copolymer having a hydroxyl group can be obtained by saponifying a part of the acetate moiety and introducing a (meth)acrylic monomer having a hydroxyl group.
In the case of a vinyl chloride/vinyl acetate copolymer having a hydroxyl group obtained by saponifying a portion of the acetate moiety, the film properties and dissolution behavior of the resin are determined by the ratio of the constituent units based on the reactive sites of vinyl chloride in the molecule (formula 1 below), the constituent units based on the reactive sites of vinyl acetate (formula 2 below), and the constituent units based on the saponification of the reactive sites of vinyl acetate (formula 3 below). That is, the constituent units based on the reactive sites of vinyl chloride impart toughness and hardness to the resin film, the constituent units based on the reactive sites of vinyl acetate impart adhesion and flexibility, and the constituent units based on the saponification of the reactive sites of vinyl acetate impart good solubility to the organic solvent system of the environmentally friendly ink composition.
Formula 1 -CH2-CHCl-
Formula 2 -CH2-CH(OCOCH3)-
Formula 3 -CH2-CH(OH)-
Such vinyl chloride/vinyl acetate copolymers may be commercially available, and examples thereof include Solvine A, AL, TA5R, TA2, TA3, TAO, TAOL, C, CH, CN, and CNL manufactured by Nissin Chemical Industry Co., Ltd.
The vinyl chloride/vinyl acetate copolymer used in the ink composition containing the polyurethane polyurea resin obtained by the present invention preferably has various functional groups in the molecule from the viewpoints of solubility in organic solvents and printability, which will be described later.
When an environmentally friendly solvent is used as the organic solvent, the vinyl chloride/vinyl acetate copolymer preferably has a hydroxyl value of 50 to 200 mgKOH/g. Commercially available vinyl chloride/vinyl acetate copolymers such as Solvine A, AL, TA5R, TA2, TA3, TAO, and TAOL manufactured by Nissin Chemical Industry Co., Ltd. are preferably used.

Vinyl chloride/acrylic copolymer as binder resin: A copolymer of vinyl chloride and an acrylic monomer is the main component. The form of the copolymer is not particularly limited, and for example, the acrylic monomer may be incorporated in the main chain of polyvinyl chloride in a block or random manner, or may be graft-copolymerized in the side chain of polyvinyl chloride.
As the acrylic monomer, a (meth)acrylic acid ester, an acrylic monomer having a hydroxyl group, etc. can be used. Examples of the (meth)acrylic acid ester include an alkyl (meth)acrylate ester, and the alkyl group may be any of linear, branched, and cyclic, but is preferably a linear alkyl group. For example, methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, cyclohexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, decyl (meth)acrylate, dodecyl (meth)acrylate, tetradecyl (meth)acrylate, hexadecyl (meth)acrylate, and octadecyl (meth)acrylate can be mentioned.
Examples of acrylic monomers having a hydroxyl group include (meth)acrylic acid hydroxyalkyl esters such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, and 8-hydroxyoctyl (meth)acrylate; glycol mono(meth)acrylates such as polyethylene glycol mono(meth)acrylate, polypropylene glycol mono(meth)acrylate, and 1,4-cyclohexanedimethanol mono(meth)acrylate; caprolactone-modified (meth)acrylate; and hydroxyethylacrylamide.
The acrylic monomer may also have a functional group other than a hydroxyl group, such as a carboxyl group, an amide bond, an amino group, or an alkylene oxide group.
The vinyl chloride/acrylic copolymer resin preferably has a mass weight average molecular weight of 10,000 to 70,000.
In addition, from the viewpoints of solubility in an environmentally friendly organic solvent and adhesion to a substrate, it is preferable that the vinyl chloride/acrylic copolymer has a hydroxyl value of 50 to 200 mg KOH/g.

Depending on the pigment to be blended, a vinyl chloride/vinyl acetate copolymer or a vinyl chloride/acrylic copolymer as a binder resin can be added in the step of adding a colorant to a polyurethane polyurea resin solution for gravure printing in order to improve adhesion.
When vinyl chloride/vinyl acetate copolymer or vinyl chloride/acrylic copolymer is contained as a binder resin, the polyurethane polyurea resin for gravure printing and (vinyl chloride/vinyl acetate copolymer and/or vinyl chloride/acrylic copolymer) can be contained in a ratio of 100/0 to 45/55 (mass ratio) of polyurethane polyurea resin for gravure printing/(vinyl chloride/vinyl acetate copolymer and/or vinyl chloride/acrylic copolymer). More preferably, this mass ratio may be 95/5 to 70/30. By containing the polyurethane polyurea resin for gravure printing and the vinyl chloride/vinyl acetate copolymer and/or vinyl chloride/acrylic copolymer in such a ratio, the gravure printing ink composition obtained by the present invention has even better printability and adhesion to films. Furthermore, when lamination processing is performed, it has even better lamination suitability.
When the ratio of the polyurethane polyurea resin for gravure printing to the vinyl chloride/vinyl acetate copolymer and/or the vinyl chloride/acrylic copolymer is less than 45/55, the proportion of the vinyl chloride/vinyl acetate copolymer and/or the vinyl chloride/acrylic copolymer becomes large, and the printed matter formed using the ink composition for gravure printing obtained according to the present invention becomes hard, and the adhesion to the film may also become insufficient.

Rosin and its derivatives as adhesion improvers Examples of rosins include gum rosin, tall oil rosin, wood rosin, etc. Generally, rosin is an amber-colored, amorphous resin obtained from pine trees, and since it is obtained naturally, it is a mixture, but it may be used after being isolated into its constituent components, namely abietic acid, neoabietic acid, palustric acid, pimaric acid, isopimaric acid, sandaracopimaric acid, and dehydroabietic acid, and these are also defined as rosin in the present invention.
The rosin derivatives are compounds obtained by modifying the above-mentioned rosins, and specific examples thereof are listed below.
(1) Hydrogenated rosin: A rosin whose weather resistance has been improved by adding hydrogen to the conjugated double bonds (hydrogenation).
(2) Disproportionated rosin: Disproportionation is a modification in which two molecules of rosin react with each other, and two molecules of abietic acid with conjugated double bonds become aromatic, while the other becomes a molecule with a single double bond. In general, it is less weather-resistant than hydrogenated rosin, but is better than untreated rosin.
(3) Rosin-modified phenolic resin: In offset printing ink compositions, rosin-modified phenolic resin is often used as the main binder. The rosin-modified phenolic resin can be obtained by a known manufacturing method.
(4) Rosin ester: an ester resin derived from rosin, which has long been used as a tackifier for adhesives and pressure sensitive adhesives.
(5) Rosin-modified maleic acid resin: a resin obtained by addition reaction of rosin with maleic anhydride, and optionally including a resin obtained by grafting a hydroxyl-containing compound such as glycerin with the anhydride group through esterification.
(6) Polymerized rosin: A derivative containing dimerized resin acid derived from natural resin rosin.
In addition, known rosins and rosin derivatives can also be used, and these can be used alone or in combination.
Furthermore, the acid value of the rosin and rosin derivative is preferably 120 mgKOH/g or more. When the acid value is 120 mgKOH/g or more, the laminate strength is improved. The acid value is more preferably 160 mgKOH/g or more. The total amount of the rosin and rosin derivative used is preferably 3.0 mass % or less, more preferably 0.1 to 3.0 mass %, based on the solid content of the ink composition for gravure printing obtained by the production method of the present invention.

Chlorinated polypropylene as an adhesion improver Chlorinated polypropylene having a degree of chlorination of 20 to 50 can be used. Chlorinated polypropylene having a degree of chlorination of less than 20 tends to have a low compatibility with organic solvents. On the other hand, when the degree of chlorination is more than 50, the adhesion of the chlorinated polypropylene to the film tends to be low. The degree of chlorination is defined as the mass % of chlorine atoms in the chlorinated polypropylene resin. The chlorinated polypropylene is preferably a modified or unmodified chlorinated polypropylene having a weight average molecular weight of 5000 to 200000. When the weight average molecular weight is less than 5000, the adhesion of the chlorinated polypropylene tends to be low. On the other hand, when the weight average molecular weight is more than 200000, the solubility of the chlorinated polypropylene in organic solvents tends to be low. The amount of the chlorinated polypropylene used is preferably 3.0 mass % or less, more preferably 0.1 to 3.0 mass %, based on the solid content of the gravure printing ink obtained by the production method of the present invention.

Dammar resin as an adhesion improver Dammar resin is also written as damar or dammar, and is a type of natural resin derived from plants. Specifically, it is a type of natural resin obtained from Dipterocarpaceae or Burseraceae plants growing in Southeast Asia such as Malaysia and Indonesia. When used, it is dissolved in an appropriate organic solvent to form a varnish. Since dammar resin does not contain chlorine, it is possible to eliminate or reduce chlorine compared to the case where a chlorinated polyolefin resin is used in the ink composition. In addition, the amount of dammar resin used is preferably 3.0% by mass or less, more preferably 0.1% by mass to 3.0% by mass, based on the solid content of the ink composition for gravure printing obtained by the production method of the present invention.

Silica particles as anti-blocking agent Examples of silica include natural products, synthetic products, crystalline, non-crystalline, hydrophobic, and hydrophilic silica. The silica particles preferably have an average particle size in the range of 1 to 5 μm (the average particle size of silica particles means the particle size at 50% cumulative value (D50) in the particle size distribution, and can be determined by the Coulter counter method). The silica particles may be hydrophilic silica having a hydrophilic functional group on the surface, or may be hydrophobic silica in which the hydrophilic functional group is modified with an alkylsilane or the like to be hydrophobic, but hydrophilic particles are preferred. An ink composition containing hydrophilic silica particles also has the effect of promoting wetting and spreading of the ink composition during overprinting, and improving the overprinting effect (hereinafter sometimes referred to as "trapping property"). The amount of silica particles used in the gravure printing ink composition obtained by the manufacturing method of the present invention is preferably 3.0% by mass or less, more preferably 0.1 to 3.0% by mass, and even more preferably 0.2 to 1.5% by mass. If the amount is more than 3.0% by mass, gloss may be reduced.

Polyethylene wax as anti-blocking agent The polyethylene wax used has an average particle size in the range of 1.0 to 20 μm (the average particle size means the particle size measured by #1 Microtrac UPA manufactured by Honeywell). If the particle size of the polyethylene wax is smaller than 1.0 μm, the slipperiness and blocking properties during the preparation of a laminate are reduced, and if the particle size is larger than 20 μm, the trapping properties are reduced. The content of the polyethylene wax in the gravure printing ink composition obtained by the production method of the present invention is preferably 0.1 to 1.5% by mass. If it is less than 0.1% by mass, the desired effect may not be obtained, and if it is more than 1.5% by mass, the gloss may be reduced.

Fatty Acid Amides as Antiblocking Agents There are no particular limitations on the fatty acid amides as long as they have a fatty acid residue and an amide group.
Examples of fatty acid amides include monoamides, substituted amides, bisamides, methylol amides, and ester amides, and at least one selected from the group consisting of monoamides, substituted amides, and bisamides is preferred because it improves blocking resistance. The amount of fatty acid amide used is preferably 1.0% by mass or less, more preferably 0.01 to 1.0% by mass, in the gravure printing ink composition obtained by the production method of the present invention.
Monoamide: Monoamide is represented by the following general formula (1):
General formula (1) R1-CONH ₂
(In the formula, R1 represents a residue obtained by removing COOH from a fatty acid.)
Specific examples of monoamides include lauric acid amide, palmitic acid amide, stearic acid amide, behenic acid amide, hydroxystearic acid amide, oleic acid amide, and erucic acid amide.
Substituted amide: The substituted amide is represented by the following general formula (2):
General formula (2) R2-CONH-R3
(In the formula, R2 and R3 represent a residue obtained by removing COOH from a fatty acid, and may be the same or different.)
Specific examples of the substituted amide include N-oleyl palmitic acid amide, N-stearyl stearic acid amide, N-stearyl oleic acid amide, N-oleyl stearic acid amide, and N-stearyl erucic acid amide.
Bisamide: Bisamide is represented by the following general formula (3) or general formula (4).
General formula (3) R4-CONH-R5-HNCO-R6
General formula (4) R7-NHCO-R8-CONH-R9
(In the formula, R4, R6, R7, and R9 represent a residue obtained by removing COOH from a fatty acid and may be the same or different, and R5 and R8 represent an alkylene group or an arylene group having 1 to 10 carbon atoms.)
Specific examples of bisamides include methylene bisstearic acid amide, ethylene biscapric acid amide, ethylene bislauric acid amide, ethylene bisstearic acid amide, ethylene bishydroxystearic acid amide, ethylene bisbehenic acid amide, hexamethylene bisstearic acid amide, hexamethylene bisbehenic acid amide, hexamethylene hydroxystearic acid amide, ethylene bisoleic acid amide, ethylene biserucic acid amide, hexamethylene bisoleic acid amide, N,N'-distearyl adipamide, N,N'-distearyl sebacic acid amide, N,N'-dioleyl adipamide, and N,N'-dioleyl sebacic acid amide.
Methylolamide: Methylolamide is represented by the following general formula (5).
General formula (5) R10-CONHCH ₂ OH
(In the formula, R10 represents a residue obtained by removing COOH from a fatty acid.)
Specific examples of methylol amides include methylol palmitic acid amide, methylol stearic acid amide, methylol behenic acid amide, methylol hydroxystearic acid amide, methylol oleic acid amide, and methylol erucic acid amide.
Ester amide: Ester amide is represented by the following general formula (6):
General formula (6) R11-CONH-R12-OCO-R13
(In the formula, R11 and R13 represent a residue obtained by removing COOH from a fatty acid and may be the same or different, and R12 represents an alkylene group or arylene group having 1 to 10 carbon atoms.)
Specific examples of ester amides include stearamide ethyl stearate, oleamide ethyl urearate, and the like.
The melting point of the fatty acid amide is preferably from 50°C to 150°C.
Moreover, the fatty acid constituting the fatty acid amide is preferably a saturated fatty acid having 12 to 22 carbon atoms and/or an unsaturated fatty acid having 16 to 25 carbon atoms, and more preferably a saturated fatty acid having 16 to 18 carbon atoms and/or an unsaturated fatty acid having 18 to 22 carbon atoms. Particularly preferred saturated fatty acids are lauric acid, palmitic acid, stearic acid, behenic acid, and hydroxystearic acid, and particularly preferred unsaturated fatty acids are oleic acid and erucic acid.

Cellulose acetate propionate resin as antiblocking agent As the cellulose acetate propionate resin, a cellulose acetate propionate resin that has been conventionally used in gravure ink compositions and the like can be used.
The cellulose acetate propionate resin is obtained by triesterifying cellulose with acetic acid and propionic acid, followed by hydrolysis. Generally, resins having 0.6 to 2.5% by weight of acetyl groups, 42 to 46% by weight of propionate groups, and 1.8 to 5% by weight of hydroxyl groups are commercially available. The amount of the cellulose acetate propionate resin used in the ink composition for gravure printing obtained by the production method of the present invention is preferably 3.0% by weight or less.

Cellulose acetate butyrate resin as anti-blocking agent As the cellulose acetate butyrate resin, a cellulose acetate butyrate resin that has been conventionally used in gravure ink compositions and the like can be used.
Cellulose acetate butyrate resin is obtained by triesterification with acetic acid and butyric acid, followed by hydrolysis. Generally, resins with 2 to 30% by weight of acetylation, 17 to 53% by weight of butyrylation, and 1 to 5% of hydroxyl groups are commercially available. The amount of cellulose acetate butyrate resin used in the ink composition for gravure printing obtained by the production method of the present invention is preferably 0.1 to 3.0% by mass.

Nitrocellulose as an Anti-blocking Agent Nitrocellulose that has been conventionally used in gravure ink compositions and the like can be used. Nitrocellulose is obtained by reacting natural cellulose with nitric acid to replace three hydroxyl groups in the six-membered ring of the anhydrous glucopyranose group in the natural cellulose with nitric acid groups to form a nitric acid ester. Nitrocellulose having a nitrogen content of 10 to 13% and an average degree of polymerization of 35 to 90 is preferably used in the present invention. Specific examples include SS1/2, SS1/4, SS1/8, TR1/16, NC RS-2, (KCNC, KOREA CNC LTD.)
The amount of soluble nitrocellulose used is preferably 2.0% by mass or less in the ink composition for gravure printing obtained by the production method of the present invention.

Pigment dispersant As the pigment dispersant, a polyester-based pigment dispersant that can be used in ink compositions such as gravure ink compositions that generally contain organic solvents can be used. Specific examples include AJISPER PB821, PB822, PB824, PB881 (manufactured by Ajinomoto Fine-Techno Co., Ltd.), Solsperse 24000, 56000 (manufactured by Lubrizol Nippon Co., Ltd.), etc., and among these, a basic group-containing polyester-based polymer dispersant can be preferably used.
The content of the pigment dispersant is preferably 1 to 200 parts by mass, and more preferably 1 to 60 parts by mass, based on 100 parts by mass of the total pigment.

Organic Solvent Any of the organic solvents described in the step of stirring and mixing the urethane prepolymer, the organic solvent, and the chain extender and/or the reaction terminator in which the amino group of the polyamine compound has been ketiminated with a ketone compound under solvent-free conditions can be used.
Furthermore, in order to improve the wetting and spreading properties, 0.1 to 20% by weight of a glycol ether-based organic solvent may be contained in 100% by weight of the organic solvent. Specific examples of the glycol ether-based organic solvent include ethylene glycol monomethyl ether, diethylene glycol monomethyl ether, ethylene glycol mono n-propyl ether, ethylene glycol monoisopropyl ether, diethylene glycol monoisopropyl ether, ethylene glycol monobutyl ether, diethylene glycol monobutyl ether, ethylene glycol monoisobutyl ether, propylene glycol monomethyl ether, dipropylene glycol monomethyl ether, propylene glycol mono n-propyl ether, diethylene glycol dimethyl ether, diethylene glycol methyl ethyl ether, diethylene glycol diethyl ether, and the like.

Water: It is preferable to contain water in order to reduce printing defects caused by static electricity, prevent plate fogging, and improve cell reproducibility. However, it is necessary that the effect of the present invention is not impaired, such as by preventing the precipitation of resins dissolved in the solvent. The amount of water used is preferably 10.0% by mass or less, and more preferably 0.1 to 5.0% by mass, in the ink composition for gravure printing obtained by the production method of the present invention.

The gravure printing ink composition of the present invention can be produced, for example, by kneading a mixture of a polyurethane polyurea resin solution for gravure printing, a pigment, and, if necessary, a binder resin, an organic solvent, a pigment dispersant, etc., using a high-speed mixer, a ball mill, a sand mill, an attritor, etc., and further adding and mixing the remaining materials such as an adhesion improver, an anti-blocking agent, an organic solvent, water, etc., as described above.

<Method for producing a laminate print using the gravure printing ink composition according to the present invention>
A method for producing a laminate print using the gravure printing ink composition obtained by the production method of the present invention will be described below.
The method for obtaining a laminate print includes at least the following printing method. For example, a gravure printing ink composition is printed at least once on a resin film that is a known substrate for lamination by gravure printing. Next, another gravure printing ink composition is printed by gravure printing at any position on the surface side of the gravure printing ink composition formed by these printings (the lower layer side as viewed from the surface layer after final lamination), and then dried by a dryer.
A resin film or the like can be laminated by various methods on the layer of the gravure printing ink composition of the printed matter obtained by the above method to obtain a laminated printed matter for packaging bags, etc. Examples of the lamination method that can be used include an extrusion lamination method in which an anchor coating agent is applied to the surface of the printed matter and then a molten polymer is laminated thereon, and a dry lamination method in which an adhesive is applied to the surface of the printed matter and then a film-like polymer is laminated thereon.

The extrusion lamination method is a method in which, if necessary, an anchor coating agent such as a titanium-based, urethane-based, imine-based, polybutadiene-based agent is applied to the surface of a printed material containing a layer of the gravure printing ink composition, and then a molten polymer is laminated using a known extrusion laminator. Furthermore, the molten resin can be laminated in a sandwich shape with other materials as an intermediate layer.
The molten polymer used in the extrusion lamination method may be a resin that has been conventionally used, such as low-density polyethylene, ethylene-vinyl acetate copolymer, polypropylene, etc. Among these, the effect of the present invention is enhanced when low-density polyethylene, which is easily oxidized during melting to generate carbonyl groups, is used.

The dry lamination method is a method in which a urethane-based, isocyanate-based or other adhesive is applied to the surface of the layer of the gravure printing ink composition, and then a film-like polymer is laminated using a known dry laminating machine. Polyethylene, non-oriented polypropylene, etc. can be used as the resin for the film used in the dry lamination method. In particular, in order to obtain a packaging material for retort applications, aluminum foil can be sandwiched between the substrate and the resin film to be laminated. Such a laminated product can also be used for boiling and retort applications after being made into a bag and filled with the contents.
Examples of the resin film used in this case include oriented and unoriented polyolefins such as polyethylene and polypropylene, polyester, nylon, cellophane, vinylon, etc. Furthermore, with regard to these resin films, films obtained by processing the resin film in advance, such as coating or kneading an anti-fogging agent, or surface coating or kneading a matting agent, can also be used.

The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. Unless otherwise specified, "%" means "% by mass" and "parts" means "parts by mass." The figures for the amounts of each material in the tables are also "parts by mass." The unit of acid value is mgKOH/g.

<Method of producing ketimine solution 1>
51 parts of isophoronediamine, 31.2 parts of N-(2-hydroxyethyl)ethylenediamine, and 174 parts of acetone were mixed and stirred at room temperature for 1 hour to obtain Ketimine Solution 1.
<Method of producing ketimine solution 2>
51 parts of isophoronediamine, 31.2 parts of N-(2-hydroxyethyl)ethylenediamine, and 258 parts of diethyl ketone were mixed and stirred at room temperature for 1 hour to obtain a ketimine solution 2.
<Method of producing ketimine solution 3>
51 parts of isophoronediamine, 31.2 parts of N-(2-hydroxyethyl)ethylenediamine, and 210 parts of methyl ethyl ketone were mixed and stirred at room temperature for 1 hour to obtain Ketimine Solution 3.
<Method of producing ketimine solution 4>
51 parts of isophoronediamine, 31.2 parts of N-(2-hydroxyethyl)ethylenediamine, and 348 parts of diacetone alcohol were mixed and stirred at room temperature for 1 hour, to obtain Ketimine Solution 4.

<Production method of PU-1 (ketiminization with acetone)>
A four-neck flask equipped with a stirrer, a cooling tube, and a nitrogen gas inlet tube was charged with 400 parts of 3-methyl-1,5-pentyleneadipate diol having a number average molecular weight of 4000, 33.3 parts of isophorone diisocyanate, and 0.04 parts of tetrabutyl titanate, and the mixture was reacted at 90 to 100° C. for 6 hours while introducing nitrogen gas.
Next, 808 parts of propyl acetate and 201 parts of isopropyl alcohol were added, and the mixture was cooled to near room temperature. 25.6 parts of Ketimine Solution 1 was added and stirred for 20 minutes, and 3 parts by mass of water was further added and stirred for 15 minutes to obtain PU-1 (solid content 30% by mass).

<Production method of PU-2 (ketiminization with diethyl ketone)>
A four-neck flask equipped with a stirrer, a cooling tube, and a nitrogen gas inlet tube was charged with 400 parts of 3-methyl-1,5-pentyleneadipate diol having a number average molecular weight of 4000, 33.3 parts of isophorone diisocyanate, and 0.04 parts of tetrabutyl titanate, and the mixture was reacted at 90 to 100° C. for 6 hours while introducing nitrogen gas.
Next, 801 parts of propyl acetate and 200 parts of isopropyl alcohol were added, and the mixture was cooled to near room temperature. 34 parts of Ketimine Solution 2 was added and stirred for 20 minutes, and 3 parts by mass of water was further added and stirred to obtain PU-2 (solid content 30% by mass).

<Production method of PU-3 (ketiminization with methyl ethyl ketone)>
A four-neck flask equipped with a stirrer, a cooling tube, and a nitrogen gas inlet tube was charged with 400 parts of 3-methyl-1,5-pentyleneadipate diol having a number average molecular weight of 4000, 33.3 parts of isophorone diisocyanate, and 0.04 parts of tetrabutyl titanate, and the mixture was reacted at 90 to 100° C. for 6 hours while introducing nitrogen gas.
Next, 805 parts of propyl acetate and 201 parts of isopropyl alcohol were added, and the mixture was cooled to near room temperature. 29.2 parts of Ketimine Solution 3 were added and stirred for 30 minutes, and 3 parts by mass of water were further added and stirred to obtain PU-3 (solid content 30% by mass).

<Production method of PU-4 (ketiminization with diacetone alcohol)>
A four-neck flask equipped with a stirrer, a cooling tube, and a nitrogen gas inlet tube was charged with 400 parts of 3-methyl-1,5-pentyleneadipate diol having a number average molecular weight of 4000, 33.3 parts of isophorone diisocyanate, and 0.04 parts of tetrabutyl titanate, and the mixture was reacted at 90 to 100° C. for 6 hours while introducing nitrogen gas.
Next, 795 parts of propyl acetate and 198 parts of isopropyl alcohol were added, and the mixture was cooled to near room temperature. 43 parts of Ketimine Solution 4 were added and stirred for 30 minutes, and 3 parts of water were further added and stirred to obtain PU-4 (solid content 30% by mass).

<PU-5 manufacturing method (biomass, ketiminization with acetone)>
A four-neck flask equipped with a stirrer, a cooling tube, and a nitrogen gas inlet tube was charged with 400 parts of a polyester diol having an average molecular weight of 4000 obtained from sebacic acid (derived from castor oil)/succinic acid (derived from plant)=70/30 (mass ratio) and 1,3-propanediol (derived from plant), 33.3 parts of isophorone diisocyanate, and 0.04 parts of tetrabutyl titanate, and the mixture was reacted at 90 to 100° C. for 6 hours while introducing nitrogen gas.
Next, 808 parts of propyl acetate and 201 parts of isopropyl alcohol were added, and the mixture was cooled to near room temperature. 25.6 parts of Ketimine Solution 1 was added and stirred for 20 minutes, and 3 parts by mass of water was further added and stirred for 15 minutes to obtain PU-5 (solid content 30% by mass).

<Production method of PU-6 (ketiminization with monoethanolamine and acetone)>
A four-neck flask equipped with a stirrer, a cooling tube, and a nitrogen gas inlet tube was charged with 400 parts of 3-methyl-1,5-pentyleneadipate diol having a number average molecular weight of 4000, 33.3 parts of isophorone diisocyanate, and 0.04 parts of tetrabutyl titanate, and the mixture was reacted at 90 to 100° C. for 6 hours while introducing nitrogen gas.
After adding 810 parts of propyl acetate and 201 parts of isopropyl alcohol, the mixture was cooled to near room temperature, 0.3 parts of monoethanolamine was added and stirred for 15 minutes, and then 23.35 parts of Ketimine Solution 1 was added and stirred for 20 minutes, and 3 parts of water was added and stirred for 15 minutes to obtain PU-6 with a mass average molecular weight of 45,000 (solid content 30%).

<PU-7 manufacturing method (adding acetone after chain extension and end termination with diamine)>
A four-neck flask equipped with a stirrer, a cooling tube, and a nitrogen gas inlet tube was charged with 400 parts of 3-methyl-1,5-pentyleneadipate diol having a number average molecular weight of 4000, 33.3 parts of isophorone diisocyanate, and 0.04 parts of tetrabutyl titanate, and the mixture was reacted at 90 to 100° C. for 6 hours while introducing nitrogen gas.
Next, 810 parts of propyl acetate and 202 parts of isopropyl alcohol were added, and the mixture was cooled to near room temperature. 5.1 parts of isophoronediamine and 3.1 parts of N-(2-hydroxyethyl)ethylenediamine were added and stirred for 30 minutes, and then 17.4 parts of acetone was added and stirred for 60 minutes to obtain PU-7 (solid content 30% by mass).

<PU-8 manufacturing method (diethyl ketone is added after chain extension and end termination with diamine)>
A four-neck flask equipped with a stirrer, a cooling tube, and a nitrogen gas inlet tube was charged with 400 parts of 3-methyl-1,5-pentyleneadipate diol having a number average molecular weight of 4000, 33.3 parts of isophorone diisocyanate, and 0.04 parts of tetrabutyl titanate, and the mixture was reacted at 90 to 100° C. for 6 hours while introducing nitrogen gas.
Next, 803 parts of propyl acetate and 201 parts of isopropyl alcohol were added, and the mixture was cooled to near room temperature. 5.1 parts of isophoronediamine and 3.1 parts of N-(2-hydroxyethyl)ethylenediamine were added and stirred for 30 minutes, and then 25.8 parts of diethyl ketone was added and stirred for 60 minutes to obtain PU-8 (solid content 30% by mass).

<PU-9 manufacturing method (chain extension and end termination with diamine, followed by addition of methyl ethyl ketone)>
A four-neck flask equipped with a stirrer, a cooling tube, and a nitrogen gas inlet tube was charged with 400 parts of 3-methyl-1,5-pentyleneadipate diol having a number average molecular weight of 4000, 33.3 parts of isophorone diisocyanate, and 0.04 parts of tetrabutyl titanate, and the mixture was reacted at 90 to 100° C. for 6 hours while introducing nitrogen gas.
Next, 807 parts of propyl acetate and 202 parts of isopropyl alcohol were added, and the mixture was cooled to near room temperature. 5.1 parts of isophoronediamine and 3.1 parts of N-(2-hydroxyethyl)ethylenediamine were added and stirred for 30 minutes, and then 21 parts of methyl ethyl ketone was added and stirred for 60 minutes to obtain PU-9 (solid content 30% by mass).

<PU-10 manufacturing method (Diacetone alcohol is charged after chain extension and end termination with diamine)>
A four-neck flask equipped with a stirrer, a cooling tube, and a nitrogen gas inlet tube was charged with 400 parts of 3-methyl-1,5-pentyleneadipate diol having a number average molecular weight of 4000, 33.3 parts of isophorone diisocyanate, and 0.04 parts of tetrabutyl titanate, and the mixture was reacted at 90 to 100° C. for 6 hours while introducing nitrogen gas.
Next, 796 parts of propyl acetate and 199 parts of isopropyl alcohol were added, and the mixture was cooled to near room temperature. 5.1 parts of isophoronediamine and 3.1 parts of N-(2-hydroxyethyl)ethylenediamine were added and stirred for 30 minutes, and then 34.8 parts of diacetone alcohol was added and stirred for 60 minutes to obtain PU-10 (solid content 30% by mass).

<PU-11 manufacturing method (biomass, chain extension with diamine, terminal termination, then acetone)>
A four-neck flask equipped with a stirrer, a cooling tube, and a nitrogen gas inlet tube was charged with 400 parts of a polyester diol having an average molecular weight of 4000 obtained from sebacic acid (derived from castor oil)/succinic acid (derived from plant)=70/30 (mass ratio) and 1,3-propanediol (derived from plant), 33.3 parts of isophorone diisocyanate, and 0.04 parts of tetrabutyl titanate, and the mixture was reacted at 90 to 100° C. for 6 hours while introducing nitrogen gas.
Next, 810 parts of propyl acetate and 202 parts of isopropyl alcohol were added, and the mixture was cooled to near room temperature. 5.1 parts of isophoronediamine and 3.1 parts of N-(2-hydroxyethyl)ethylenediamine were added and stirred for 30 minutes, and then 17.4 parts of acetone was added and stirred for 60 minutes to obtain PU-11 (solid content 30% by mass).

<PU-12 manufacturing method (reaction stopped with monoethanolamine, chain extension with diamine, terminal termination, and then acetone is added)>
A four-neck flask equipped with a stirrer, a cooling tube, and a nitrogen gas inlet tube was charged with 400 parts of 3-methyl-1,5-pentyleneadipate diol having a number average molecular weight of 4000, 33.3 parts of isophorone diisocyanate, and 0.04 parts of tetrabutyl titanate, and the mixture was reacted at 90 to 100° C. for 6 hours while introducing nitrogen gas.
After adding 810 parts of propyl acetate and 201 parts of isopropyl alcohol, the mixture was cooled to near room temperature, and 0.3 parts of monoethanolamine was added and stirred for 15 minutes. Then, 4.65 parts of isophoronediamine and 2.84 parts of N-(2-hydroxyethyl)ethylenediamine were added and stirred for 30 minutes, and then 15.86 parts of acetone was added and stirred for 60 minutes to obtain PU-12 (solid content 30% by mass).

<Production method of PU-13 (chain extension and end termination with diamine)>
A four-neck flask equipped with a stirrer, a cooling tube, and a nitrogen gas inlet tube was charged with 400 parts of 3-methyl-1,5-pentyleneadipate diol having a number average molecular weight of 4000, 33.3 parts of isophorone diisocyanate, and 0.04 parts of tetrabutyl titanate, and the mixture was reacted at 90 to 100° C. for 6 hours while introducing nitrogen gas.
Next, 823.9 parts of propyl acetate and 205.5 parts of isopropyl alcohol were added, and the mixture was cooled to near room temperature. 5.1 parts of isophoronediamine and 3.1 parts of N-(2-hydroxyethyl)ethylenediamine were added and stirred for 30 minutes to obtain PU-13 (solid content 30% by mass).

(Pigment)
Titanium oxide (R-960, manufactured by DuPont)
Phthalocyanine Blue (Pigment Blue 15:4)
<Silica particles>
Silica particles with an average particle size of 4.5 μm

<Production Examples of Ink Compositions in Examples and Comparative Examples>
The pigment, polyurethane resin varnish (PU-1 to PU-13), silica and solvent were kneaded using a paint conditioner manufactured by Red Devil Co., Ltd., to obtain the ink compositions of the examples and comparative examples shown in Table 1.

<Temperature stability of ink composition>
The ink compositions of the Examples and Comparative Examples obtained above were put into glass bottles, and the viscosity stability over time was evaluated based on the change in viscosity before and after aging at 40°C for 14 days (the viscosity at a liquid temperature of 25°C was measured using a No. 2 rotor of a B-type viscometer (manufactured by Tokyo Keiki Co., Ltd.) at 30 rpm), and the evaluation was performed according to the following evaluation criteria. The results are shown in Table 1.
Good: The viscosity ratio after aging/before aging was less than 1.5.
x: The viscosity ratio after aging/before aging is 1.5 or more, and no settling is observed.

<Production of printed matter>
100 parts by mass of each of the ink compositions of the Examples and Comparative Examples was diluted with a mixed solvent (ethyl acetate/propyl acetate/isopropyl alcohol = 50/25/25, mass ratio) and the viscosity was adjusted to 15 seconds using Zahn Cup No. 3 manufactured by Rigo Co., Ltd., to obtain ink compositions with adjusted concentrations.
Each of the obtained ink compositions was used to print on the treated surface of a polypropylene film (P-2161 manufactured by Toyobo Co., Ltd.) under the following conditions, followed by drying to obtain a print.
Furthermore, the obtained prints were evaluated for amine odor and ketimine odor. The specific evaluation method is shown below.

(Printing method/printing conditions)
Printing room environment: Temperature 25°C, humidity 50%
Coating machine: Gravure printing machine
Coating speed: 150 m/min
Printing plate: Direct 175 lines 28 μm solid plate Drying temperature: 55° C.

(Method for evaluating amine odor and ketimine odor on printed matter)
The printed surface of each of the resulting prints was placed against the nose and the odor was evaluated in a sensory test according to the following criteria. The results are shown in Table 1.
◯: No amine odor or ketimine odor is observed.
△: A slight amine odor or ketimine odor is observed.
×: Amine odor/ketimine odor is observed.

The ink compositions of Examples 1 to 7, which used the polyurethane polyurea resin obtained by the method of the present invention, had excellent stability over time. In addition, the printed parts had no amine odor or ketimine odor after being made into printed matter.
In contrast, the ink compositions of Comparative Examples 1 to 7, which were not produced according to the method of the present invention and used polyurethane polyurea resins that had not been ketiminated, were inferior in stability over time. In addition, the printed parts had a ketimine odor after being printed. The ink compositions of Comparative Examples 8 and 9, which used polyurethane polyurea resins obtained by a method of only chain extension and terminal termination with diamine, were slightly inferior in stability over time. In addition, the printed parts had an amine odor after being printed.

Claims (4)

A method for producing an ink composition for gravure printing, comprising the following steps A to E:
A. A process for synthesizing a urethane prepolymer from an organic diisocyanate compound and a polymeric diol compound;
B. A step of mixing a urethane prepolymer with an organic solvent to obtain a urethane prepolymer solution;
C. A step of adding a compound in which an amino group of a polyamine compound is ketiminated with a ketone compound to the urethane prepolymer solution and mixing the compound;
D. A process of adding water under the following conditions to extend the chain and/or terminate the reaction, thereby obtaining a polyurethane polyurea resin solution for gravure printing;
Condition: Within a range in which the polyurethane polyurea resin for gravure printing obtained by the method for producing a polyurethane polyurea resin for gravure printing does not precipitate. E. A step of adding a colorant to a polyurethane polyurea resin solution for gravure printing The method for producing an ink composition for gravure printing according to claim 1, wherein the ratio of the organic diisocyanate compound to the polymer diol used is such that the equivalent ratio of isocyanate groups to hydroxyl groups (isocyanate index) is NCO groups/OH groups = 1.2 to 3.0. The method for producing an ink composition for gravure printing according to claim 1 or 2, wherein the organic solvent is a mixed solvent of an ester-based organic solvent and an alcohol-based organic solvent, or an ester-based organic solvent. The method for producing an ink composition for gravure printing according to any one of claims 1 to 3, wherein the ketiminated compound is a compound in which the amino group of a polyamine compound is ketiminated with one or more ketone compounds selected from acetone, diethyl ketone, methyl ethyl ketone, and diacetone alcohol.