JP7238715B2 - water-based gravure or flexographic inks, prints and laminates - Google Patents

Description

The present invention relates to aqueous gravure or flexographic inks, prints and laminates.

In recent years, in printing inks, especially gravure or flexographic inks (hereinafter abbreviated as inks), there have been concerns about safety and health during work due to the organic solvent that is the medium of the ink, suitability for the work environment, and packaging when using the ink. From the standpoint of reducing residual solvents in materials, the demand for water-based inks is stronger than before. In water-based inks, water-based polyurethane resins are used as the main binder resin because of their good adhesion to substrates, particularly in printing on plastic substrates. Such printed matter is further subjected to a lamination process to form a laminate, which is often used as a packaging bag for foods, medicines, and the like. For example, Patent Documents 1 to 3 disclose technical developments related to water-based polyurethane resins for inks.

In recent years, the above-mentioned packaging bags have been diversified and packaging technology has been advanced, and high functionality (moisture resistance, oxygen barrier, heat resistance, retort resistance, etc.) has been achieved not only with solvent-based inks, but also with water-based inks. is sought in any case. Even if conventional water-based inks satisfy adhesiveness, laminating suitability, and printability to plastic substrates, they often fail to satisfy boiling resistance and retorting resistance. rice field. For example, in Patent Document 4, a polyurethane resin having a polyester structure as a main skeleton is used. Boiling resistance suitability and retort resistance suitability are important physical properties that are essential depending on the layer structure of the laminate or the applicable range and type of the packaging bag.

Moreover, in recent years, the above laminates and packaging bags are often used for foods that require long-term storage (the contents of conventional cans or bottles). This is for the purpose of reducing waste and reducing VOCs. Products to be stored for a long period of time are exposed to indoor light and sunlight for a long period of time, such as in stores and at home. For example, in Patent Document 5, since polyol having an ether structure is used in large amounts as a raw material for the water-based polyurethane resin, there is a high possibility that the ether skeleton in the polyurethane resin will be cleaved by ultraviolet rays, resulting in poor light resistance. When the ink layer of the packaging bag is deteriorated by ultraviolet rays, the color tone of the ink layer is lost, and the laminated state of the packaging bag is adversely affected. Cited Document 6 does not use a liquid aliphatic polycarbonate polyol, so the light resistance after 12 hours of UV irradiation is not sufficient.

Conventional water-based inks generally tend to be inferior to solvent-based inks in boilability, retort resistance, and lightfastness. Therefore, the types of plastic substrates that can be used and the laminate structure of the laminated laminate are limited, and this often hinders the sophistication of packaging bags in the case of using water-based ink.
Furthermore, with conventional water-based inks, if the water resistance and retort resistance are improved, the light resistance tends to be inferior, or if the light resistance is improved, the water resistance and retort resistance tend to be inferior, and it is difficult to achieve both physical properties. . Therefore, no water-based gravure ink or flexographic ink has been developed which satisfies the above boiling resistance, retorting resistance and light resistance.

JP-A-2008-49706 Japanese Unexamined Patent Application Publication No. 2001-40057 JP-A-2005-272587 JP 2013-234214 A Japanese Patent Application Laid-Open No. 2004-189968 JP-A-11-293191

An object of the present invention is to provide a water-based gravure or flexo ink excellent in light resistance, retort resistance, laminate strength, and printability, as well as printed materials and laminates using the same.

The inventors conducted intensive studies, found that the problem can be solved by using the following means, and completed the present invention.

That is, the present invention provides a water-based gravure or flexographic ink for lamination containing a water-based polyurethane resin,
The aqueous polyurethane resin has a glass transition temperature of −40 to 0° C., a hydroxyl value of 0.1 to 15 mgKOH/g, and an acid value of 15 to 60 mgKOH/g.
Further, the water-based polyurethane resin contains structural units derived from an aliphatic polycarbonate polyol, and the aliphatic polycarbonate polyol is liquid at 25°C.

The present invention also relates to the water-based gravure or flexo ink, wherein the aliphatic polycarbonate polyol contains a structural unit derived from a branched diol having tertiary carbon and/or quaternary carbon.

The present invention also relates to the water-based gravure or flexo ink, wherein the aliphatic polycarbonate polyol has a branched diol having tertiary carbon and/or quaternary carbon and an aliphatic diol having a linear structure as structural units.

Further, in the present invention, the mass ratio of the branched diol having a tertiary carbon and/or a quaternary carbon and the aliphatic diol having a linear structure (the former: the latter) is 95:5 to 30:70. It relates to the water-based gravure or flexo ink.

The present invention also relates to the water-based gravure or flexo ink, wherein the water-based polyurethane resin contains 2 to 30% by mass of polyethylene glycol-derived structural units in the total weight of the water-based polyurethane resin.

The present invention also relates to a printed material having a print layer made of the water-based gravure or flexographic ink on the substrate 1 .

The present invention also relates to a laminate having an adhesive layer and a substrate 2 in this order on the printed layer of the printed matter.

ADVANTAGE OF THE INVENTION By this invention, the water-based gravure or flexographic ink which was excellent in light resistance, retort-resistant suitability, laminate strength, and printability, the printed matter using the same, and the laminated body were able to be provided.

Preferred embodiments of the present invention are described below, but the following are examples of the embodiments of the present invention, and the present invention is not limited to these embodiments.

In this specification, "aqueous gravure or flexographic ink" may be simply referred to as "ink" or "printing ink", but they have the same meaning. A printed layer made of water-based gravure or flexographic ink may be described as "ink layer", "ink film" or "printed layer", but they have the same meaning.

<Aqueous polyurethane resin>
In the present invention, the aqueous polyurethane resin functions as a binder resin, contains a structural unit derived from an aliphatic polycarbonate polyol, has a glass transition temperature of −40 to 0° C., and a hydroxyl value of 0.1 to 15 mgKOH/ and contains a polyurethane resin having an acid value of 15 to 60 mgKOH/g. The aliphatic polycarbonate polyol structure has the effect of achieving both light resistance and retort resistance, and the glass transition temperature within this range provides the effect of excellent lamination strength. Furthermore, since the hydroxyl value is within the above range, the effect of balancing the dispersibility and solubility in water of the polyurethane resin and the suitability for retort resistance is achieved. It is inferred that the characteristics of are improved and compatible. However, the present invention is not limited by these conjectures.

The water-based polyurethane resin has a glass transition temperature of -40 to 0°C, preferably -25 to 0°C, more preferably -20 to -5°C. In this specification, the glass transition temperature means the temperature at the maximum value of tan δ in dynamic viscoelasticity measurement. For example, after drying the water-based polyurethane resin to form a dry coating film, it can be measured with a dynamic viscoelasticity measuring device DVA-200 manufactured by IT Keisoku Co., Ltd. By setting the glass transition temperature within the relevant range, both blocking resistance and lamination suitability can be achieved.

The hydroxyl value of the aqueous polyurethane resin in the present embodiment may be 0.1 to 15 mgKOH/g, preferably 0.1 to 10 mgKOH/g, and more preferably 0.5 to 8 mgKOH/g. . More preferably 2 to 7 mg KOH/g. This is because the dispersibility of the water-based polyurethane resin in water, the dispersibility of the pigment, and the adhesion to the substrate are improved. The hydroxyl value is a value obtained by converting the amount of hydroxyl groups in 1 g of resin, which is calculated by esterifying or acetylating the hydroxyl groups in the resin and back-titrating the remaining acid with an alkali, into mg of potassium hydroxide, according to JIS K0070. It is the value that went.

The acid value of the water-based polyurethane resin may be from 15 to 60 mgKOH/g, preferably from 15 to 55 mgKOH/g, and more preferably from 15 to 45 mgKOH/g. More preferably 15 to 40 mgKOH/g. The water-based polyurethane resin has an acid value of 15 mgKOH/g or more, and the acidic functional groups are neutralized with a basic compound, so that the dispersibility and solubility in water are sufficient, and the pigment dispersibility and re-dissolution of the ink are obtained. It promotes the improvement of printability and printability. Further, if the acid value of the water-based polyurethane resin is 65 mgKOH/g or less, the water resistance of the ink film when used as a binder is not impaired. As the acidic functional group, a carboxyl group, a sulfonic acid group, and the like are preferably mentioned.

(basic compound)
The polyurethane resin is made water-based by neutralizing the acidic functional groups it has with a basic compound. Examples of the basic compound include sodium hydroxide, potassium hydroxide, ammonia, methylamine, ethylamine, propylamine, butylamine, hexylamine, octylamine, ethanolamine, propanolamine, diethanolamine, N-methyldiethanolamine, dimethylamine, and diethylamine. , triethylamine, N,N-dimethylethanolamine, 2-dimethylamino-2-methyl-1-propanol, 2-amino-2-methyl-1-propanol, and morpholine. Used in combinations of more than one species. Depending on the type of the basic compound, the compatibility with the polyurethane resin solution or the stability after making it water-based may differ, so it is necessary to select an appropriate one. Of these, ammonia and alkyl-substituted amines are preferred, and ammonia is more preferred, from the viewpoint of water resistance of printed matter, residual odor, and the like.

(Structure of water-based polyurethane resin)
The water-based polyurethane resin is not limited to the following, but includes, for example, a polyol containing at least an aliphatic polycarbonate polyol, a compound having a carboxyl group and at least two active hydrogen-containing groups in the molecule, and a polyisocyanate. Reactant aqueous polyurethane resins are preferred.

(polyol)
Polyols used in aqueous polyurethane resins include aliphatic polycarbonate polyols, and may further include polyether polyols, polyester polyols, polycaprolactone polyols, and the like. These can be used singly or in combination of two or more.

(aliphatic polycarbonate polyol)
The aliphatic polycarbonate polyol in this embodiment has two or more hydroxyl groups and two or more carbonate bonds in the molecule. The average number of hydroxyl groups possessed by the aliphatic polycarbonate polyol may be 1.5 to 2.5. In addition, those having two or more hydroxyl groups and one carbonate bond in the molecule may also be included.
Although the aliphatic polycarbonate polyol is not limited by the production method, it is preferably a polycondensate obtained by transesterification of an aliphatic diol and a carbonate compound, for example.
In the present invention, "aliphatic diol" does not include cycloaliphatic. Aliphatic diols are preferably in the form of substituted or unsubstituted alkylene glycol. Moreover, as an aliphatic diol, those obtained by condensing a plurality of alkylene glycols via an ether bond or an ester bond can also be mentioned. Among the aliphatic diols, an aliphatic diol in which at least one hydrogen atom of the alkylene group of the alkylene glycol is replaced with a non-hydrogen atom is called a branched diol. Therefore, the aliphatic polycarbonate polyol is distinguished from those having a cycloalkylene group or other alicyclic structures. The branched diol preferably contains tertiary carbon and/or quaternary carbon as the carbon having a substituent, and more preferably contains tertiary carbon.
The aliphatic diol preferably has 4 to 10 carbon atoms, such as ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,5 -pentanediol, 2-methyl-1,3-propanediol, neopentyl glycol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, 1,8-octanediol, 1,9-nonanediol , 2-methyl-1,8-octanediol, 1,10-decanediol, 2-butyl-2-ethyl-1,3-propanediol, 1,4-butynediol, 2,2,4-trimethyl-1 ,3-pentanediol, 1,4-cyclohexanedimethanol, diethylene glycol, polypropylene glycol, dipropylene glycol and the like are suitable, and these can be used alone or in combination of two or more. In addition, it is preferable that the substituent which the alkylene glycol has is an alkyl group having 10 or less carbon atoms.
The aliphatic polycarbonate polyol preferably has a number average molecular weight of 500 to 5,000, more preferably 800 to 4,000. It is more preferably 1000-3000. In addition, it is preferable that it is an aliphatic polycarbonate diol.

The carbonate compound mentioned above includes, but is not limited to, dialkyl carbonate, diaryl carbonate, or alkylene carbonate. Specific examples of carbonate compounds include dialkyl carbonates such as dimethyl carbonate, diethyl carbonate and dibutyl carbonate, diaryl carbonates such as diphenyl carbonate, and alkylene carbonates such as ethylene carbonate. The structure of the carbonate compound is not limited, and a compound having good reactivity may be appropriately selected because it becomes a polycondensate in a transesterification reaction with a substituted or unsubstituted alkylene glycol and is substituted.
When diaryl carbonate or alkylaryl carbonate is used as a raw material, unreacted raw materials may remain or a carbonate monool having an aryl group at the end may be produced as a by-product. It does not exclude the presence of non-aliphatic carbonates in the ink within the technical scope of the present invention.

The aliphatic polycarbonate polyol is preferably liquid at 25°C. By using a liquid aliphatic polycarbonate polyol, the flexibility of the ink film containing the water-based polyurethane resin can be obtained, and thus lamination suitability is improved. In addition, since it is liquid, it has good wettability to the pigment, and the high cohesion of the carbonate bond makes it difficult to detach from the pigment, so it is excellent in pigment dispersion and improves the stability of diluted ink. For example, as the aliphatic diol component, an aliphatic diol having an odd number of carbon atoms and having a linear structure, an aliphatic polycarbonate polyol using an aliphatic diol having an even number of carbon atoms and having a linear structure, and an alkyl substituent Aliphatic polycarbonate polyols having alkylene glycols (branched diols) having (alkyl groups) as structural units, and the like are suitable. Further, an aliphatic polycarbonate polyol containing structural units derived from a branched diol and an aliphatic diol having a linear structure is preferred.
In the branched diol, the alkyl group is preferably an alkyl group having 6 or less carbon atoms, more preferably an alkyl group having 4 or less carbon atoms. More preferably, it is a methyl group.

The aliphatic polycarbonate polyol is preferably an aliphatic polycarbonate polyol having an aliphatic diol containing the following branched diol as a structural unit.
Branched diols having tertiary and/or quaternary carbons are preferred as such branched diols. This is because lamination aptitude and the like are improved. Branched diols with tertiary carbons are, for example, 1,2-propanediol, 2-methyl-1,3-propanediol, 3-methyl-1,5-pentanediol, 2-methyl-1,8-octanediol , 2,2,4-trimethyl-1,3-pentanediol, etc., preferably 3-methyl-1,5-pentanediol. Branched diols having quaternary carbon atoms are preferably exemplified by neopentyl glycol, 2-butyl-2-ethyl-1,3-propanediol, and the like. In addition, these branched diols are not limited to those illustrated.

Further, the aliphatic polycarbonate polyol preferably has the following aspects. It preferably has a structural unit, and the mass ratio (former: latter) in the total mass of aliphatic polycarbonate polyol is preferably 95:5 to 30:70, more preferably 95:5 to 40:60. . More preferably 90:10 to 50:50.
Constituent units of the aliphatic polycarbonate polyol preferably contain a branched diol having a tertiary carbon and an aliphatic diol having a linear structure. The mass ratio is preferably the same as above. The branched diol preferably contains 3-methyl-1,5-pentanediol, and the diol having a linear structure preferably contains 1,6-hexanediol.

Since both light resistance and retort resistance can be achieved at a higher level, the aqueous polyurethane resin preferably contains 30 to 75% by mass of aliphatic polycarbonate polyol-derived structural units in the total weight of the aqueous polyurethane resin, and 40 to 65% by mass. % by mass is more preferred, and 50 to 65% by mass is even more preferred.

(polyether polyol)
The water-based polyurethane resin preferably contains structural units derived from polyether polyol. Polyether polyols include polymers or copolymers such as methylene oxide, ethylene oxide, propylene oxide, and tetrahydrofuran, and polyethylene glycol. , polypropylene glycol, polytetramethylene glycol and copolymers thereof are preferred. These can be used alone or in combination of two or more. The aqueous polyurethane resin preferably contains 2 to 30% by mass of polyethylene glycol-derived structural units in the total weight of the aqueous polyurethane resin, more preferably 2 to 30% by mass. 10% by mass. Containing a structural unit derived from polyethylene glycol increases the solubility in water, and the water resistance can be ensured by adjusting the content to 2 to 30% by mass.

(polyester polyol)
When polyester polyol is used for the aqueous polyurethane resin, for example, ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,3-butanediol, pentanediol, 2-methyl-1,3-propane Diol, neopentyl glycol, 3-methyl-1,5-pentanediol, hexanediol, octanediol, 1,9-nonanediol, 2-methyl-1,8-octanediol, 2-butyl-2-ethyl- Low molecular weight polyols such as 1,3-propanediol, 1,4-butynediol, 2,2,4-trimethyl-1,3-pentanediol, 1,4-cyclohexanedimethanol, diethylene glycol, polypropylene glycol and dipropylene glycol and adipic acid, phthalic acid, isophthalic acid, terephthalic acid, maleic acid, fumaric acid, succinic acid, oxalic acid, malonic acid, glutaric acid, pimelic acid, spelic acid, azelaic acid, sebacic acid, trimellitic acid, pyro Polyvalent carboxylic acids such as mellitic acid or dehydration condensates or polymers with these anhydrides can be mentioned. These can be used alone or in combination of two or more.
Polycaprolactone polyol in the present invention is obtained by ring-opening polymerization of ε-caprolactone.

(polyisocyanate)
As the polyisocyanate used in the aqueous polyurethane resin of the present invention, various known aromatic, aliphatic or alicyclic diisocyanates can be used. For example, 1,5-naphthylene diisocyanate, 4,4′-diphenylmethane diisocyanate, 4,4′-diphenyldimethylmethane diisocyanate, 4,4′-dibenzyl isocyanate, dialkyldiphenylmethane diisocyanate, tetraalkyldiphenylmethane diisocyanate, 1,3- Phenylene diisocyanate, 1,4-phenylene diisocyanate, tolylene diisocyanate, butane-1,4-diisocyanate, hexamethylene diisocyanate, 1,5-pentamethylene diisocyanate, isopropylene diisocyanate, methylene diisocyanate, 2,2,4-trimethylhexamethylene Diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, cyclohexane-1,4-diisocyanate, xylylene diisocyanate, isophorone diisocyanate, lysine diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, 1,3-bis(isocyanatomethyl) Representative examples include cyclohexane, methylcyclohexane diisocyanate, m-tetramethylxylylene diisocyanate, and dimer diisocyanate obtained by converting the carboxyl group of dimer acid to an isocyanate group. These can be used alone or in combination of two or more. Isophorone diisocyanate is preferred from the viewpoint of reactivity and the like.

(Compound having a carboxyl group and at least two active hydrogen-containing groups in the molecule)
Compounds having a carboxyl group and at least two active hydrogen-containing groups in the molecule used in the aqueous polyurethane resin of the present invention include, for example, 2,2-dimethylolpropionic acid, 2,2-dimethylolbutanoic acid, 2, Examples thereof include dimethylolalkanoic acids such as 2-dimethylolbutyric acid and 2,2-dimethylolvaleric acid, and one or more of these may be used in combination. Among them, it is preferable to use 2,2-dimethylolpropionic acid and/or 2,2-dimethylolbutanoic acid in terms of compatibility and reactivity with other urethane raw materials. The active hydrogen-containing group is preferably a hydroxyl group. Since the carboxyl group has low reactivity in the process of synthesizing the polyurethane resin, most of it is contained in the polyurethane resin as an acid value for neutralization.

The water-based polyurethane resin in the present embodiment can be produced as appropriate, for example, by the method described in JP-A-2013-234214. Acetone method using an organic solvent is preferred.

The water-based polyurethane resin preferably has a urea bond by chain extension with a polyamine. The water-based polyurethane resin having a urea bond is, for example, a polyol containing at least an aliphatic polycarbonate polyol, a compound having a carboxyl group and at least two active hydrogen-containing groups in the molecule, and a polyisocyanate reacted with an isocyanate group at the end. It can be produced by previously producing a urethane prepolymer to be contained and further chain-extending it with a polyamine.

(polyamine)
The polyamines include, for example, ethylenediamine, propylenediamine, hexamethylenediamine, isophoronediamine, dicyclohexylmethane-4,4′-diamine, dimerdiamine obtained by converting the carboxyl group of dimer acid into an amino group, 2-hydroxyethylethylenediamine, 2 -Hydroxyethylpropylenediamine, di-2-hydroxyethylethylenediamine, di-2-hydroxyethylpropylenediamine, 2-hydroxypropylethylenediamine, di-2-hydroxypropylethylenediamine, etc. can be used, and polyamines having hydroxyl groups are preferred. be. The polyurethane resin having structural units composed of a polyamine having a hydroxyl group contributes to the improvement of dispersibility and solubility in water. In addition, since polyamines having hydroxyl groups preferentially react with amino groups, it is possible to allow the polyurethane resin to contain predetermined hydroxyl groups.
Polyamine These can be used alone or in combination of two or more. More preferred are isophoronediamine and 2-hydroxyethylethylenediamine (2-aminoethylethanolamine).

The weight average molecular weight (GPC measurement, standard polystyrene conversion) of the aqueous polyurethane resin is not particularly limited, but is preferably 10,000 to 100,000, more preferably 20,000 to 60,000.

The content of the water-based polyurethane resin is preferably 4 to 25% by mass, more preferably 5 to 18% by mass, and still more preferably 5 to 15% by mass in the total mass of the ink.

(medium)
Although the water-based ink in the present embodiment contains water as a medium, it may contain organic solvents such as alcohol-based, ketone-based, and ester-based solvents. Solvents are preferred. Specific examples include methanol, ethanol, n-propanol, isopropyl alcohol, 1-butanol, 2-methyl-1-propanol, 2-butanol, 2-methyl-2-propanol, ethylene glycol, propylene glycol, and diethylene glycol. Among them, n-propanol and/or isopropyl alcohol are preferred. The organic solvent is preferably contained in an amount of 20% by mass or less, more preferably 10% by mass or less, based on the total mass of the ink.

(coloring agent)
Examples of the coloring agent blended to have the functions required for the water-based printing ink of the present invention include organic and inorganic pigments and dyes used in general inks, paints, recording agents, and the like. . Examples of organic pigments include azo, phthalocyanine, anthraquinone, perylene, perinone, quinacridone, thioindigo, dioxazine, isoindolinone, quinophthalone, azomethineazo, ditopyrrolopyrrole, and isoindoline pigments. pigments. Examples of inorganic pigments include carbon black, titanium oxide, zinc oxide, zinc sulfide, barium sulfate, calcium carbonate, chromium oxide, silica, red iron oxide, aluminum, and mica (mica). From the viewpoint of cost and coloring power, it is preferable to use titanium oxide for white ink, carbon black for black ink, aluminum for gold and silver inks, and mica for pearl ink.

The colorant is preferably contained in an amount sufficient to ensure the density and coloring power of the ink, that is, in a proportion of 1 to 50% by mass with respect to the total mass of the ink. Further, the colorants can be used singly or in combination of two or more.

(Additive)
The water-based ink in the present embodiment can contain known additives such as antifoaming agents, thickeners, leveling agents, pigment dispersants, curing agents, and ultraviolet absorbers, if necessary.

In order to stably disperse the pigment in the aqueous medium, the water-based polyurethane resin of the present invention can be used alone, but a dispersant can also be used in combination to stably disperse the pigment. Anionic, nonionic, cationic, and amphoteric surfactants can be used as dispersants. The dispersant is preferably contained in the ink in an amount of 0.05% by mass or more relative to the total mass of the ink from the viewpoint of storage stability of the ink, and 5% by mass or less from the viewpoint of laminate strength, and more preferably 0% by mass. .1 to 2% by mass.

(curing agent)
The water-based gravure or flexographic ink of the present invention can be improved in adhesion to the substrate, lamination strength, and water resistance by cross-linking the water-based polyurethane resin with a curing agent. Since the water-based polyurethane resin has a carboxyl group, it is preferable to use a hydrazine-based compound, a carbodiimide compound, or an epoxy compound as a curing agent.
Preferred hydrazine-based compounds are dihydrazide adipic acid, dihydrazide sebacate, dihydrazide isophthalate and other dihydrazide compounds.
The carbodiimide compound is a compound having a carbodiimide group, and examples thereof include Carbodilite E-02, E-03A, SV-02, V-02, V02-L2, V-04 manufactured by Nisshinbo.
An epoxy compound means a compound having an epoxy group, and examples thereof include alicyclic epoxies such as ADEKA ADEKA RESIN EP-4000, EP-4005 and 7001.
The curing agent is preferably used in an amount of 0.05 to 5% by weight, more preferably 0.1 to 3% by weight, based on the total weight of the ink.

(Other resins)
In addition, water-based resins other than the above water-based polyurethane resins may be included as long as the functions and effects of the present invention are not impaired. Examples of such resins include conventional water-based polyurethane resins other than the above-mentioned water-based polyurethane resins, water-based polyester resins, water-based acrylic resins, water-based styrene-acrylic resins, water-based styrene-maleic anhydride resins, water-based rosin-modified maleic acid resins, and water-based cellulose. water-based resins, water-based vinyl chloride copolymer resins, and water-based chlorinated polyolefins.

(Production of water-based gravure or flexo ink)
The method for producing the water-based gravure or flexo ink is not particularly limited, but it can be preferably produced by mixing or dispersing the ingredients using, for example, a ball mill, an attritor, or a bead mill. For example, it can be produced by mixing a pigment, an aqueous polyurethane resin, and water with a disper for about 20 minutes and then dispersing them with a sand mill or other bead mill for about 10 to 60 minutes.

The ink viscosity of the water-based ink produced by the above method is in the range of 10 mPa s or more from the viewpoint of preventing sedimentation of the pigment and appropriately dispersing it, and 1000 mPa s or less from the viewpoint of work efficiency during ink production or printing. Preferably. As the viscosity, a viscosity measured at 25° C. with a Brookfield viscometer can be used.

The printed matter in this embodiment has a printed layer formed on the surface of a plastic substrate using the water-based ink described above. Either the gravure printing method or the flexographic printing method can be used depending on the intended printed material.

(Base material 1)
The type and thickness of the substrate are not particularly limited, but it is preferably in the form of a plastic film. Deposits of oxides and the like can be mentioned. In the case of a polyolefin substrate, a corona discharge-treated polyolefin substrate having a functional group such as a hydroxyl group or a carbonyl group can be used to obtain good printed matter. The plastic substrate is preferably a uniaxially or biaxially stretched substrate. Printed matter is always treated as a rolled matter, and then cut into a specific size through a laminating process, a slitting process, etc., if necessary.

The method for producing a plastic substrate printed material in this embodiment includes printing on the surface of a wound plastic substrate using the water-based ink described above. After printing, processes such as lamination, slitting (cutting unnecessary width portions), and bag making (cutting and heat-sealing to form bags) can be performed.

Both the gravure printing method and the flexographic printing method are roll-up printing methods, enabling high-speed printing and excellent productivity.
Gravure printing usually uses a gravure plate with cells (recesses) for expressing patterns and/or characters on the peripheral surface of a cylindrical cylinder. A printing method in which the printing ink filled in the cells is transferred to the material to be printed by passing the material) between the gravure plate and the impression cylinder, thereby reproducing patterns and/or characters on the material to be printed. be.
In flexographic printing, ink is supplied directly from a container for storing printing ink or via an ink supply pump or the like to an anilox roller having an uneven surface. It is transferred to the plate surface by contact with the plastic substrate, and finally transferred to the plastic substrate by contact between the plate surface and the plastic substrate to form a pattern and/or characters.

Since the plastic substrate is of a winding type, it is in the form of a roll with a specified width. Therefore, it differs from the sheet form in which each sheet is cut in advance. The width of the substrate is appropriately selected based on the plate width of the printing machine to be used and the width of the image (pattern) portion of the gravure plate. When multiple colors of printing inks are printed in layers, the printing order of the inks is not particularly limited.

When printing in gravure and flexographic printing methods, in the case of reverse printing, which is preferably used for lamination, the web plastic substrate is first printed with colored ink and then printed with white ink. is common. When multiple colors of ink are used, for example, printing can be performed in the order of black, cyan, magenta, and yellow, but there is no particular limitation. In large-sized printing presses, special colors and the like can be used in addition to the basic colors. That is, a large-sized printing press has a plurality of printing units corresponding to 5 to 10 colors, one printing unit is provided with ink of one color, and 5 to 10 colors of overprinting can be performed at one time.

(Laminate)
The laminate in the present invention can be obtained through a step of laminating a substrate on the printed layer of the printed matter. It can be obtained by applying an anchor coating agent, a molten resin, an adhesive, or the like on the printed layer, drying it, and bonding it to the substrate 2 . The substrate 2 may be the same as or different from the substrate 1 described above. In the laminate, the printed layer made of water-based gravure or flexographic ink is positioned as an intermediate layer (for example, base material 1/printed layer/adhesive layer/base material 2).

As the lamination method, 1) an extrusion lamination method in which an anchor coating agent is applied on the printed layer of the obtained printed material as necessary, and then the molten resin and the base material 2 are laminated in this order, or 2) ) A dry lamination method of applying an adhesive on the printed layer of the obtained printed matter, drying it if necessary, and laminating the base material 2, and the like. Low-density polyethylene, polypropylene, ethylene-vinyl acetate copolymer, and the like can be used as the molten resin, and imine, isocyanate, polybutadiene, and titanate adhesives can be used as the anchor coating agent. As the adhesive, a urethane adhesive is suitable, and a two-liquid adhesive is more suitable. For example, ether-based urethane adhesives, ester-based urethane adhesives, etc. correspond to this.

A laminated laminate can be preferably used as a packaging material, and is preferably used as a general packaging material, particularly as a packaging material for food.

Specific examples of the present invention will be described below together with comparative examples, but the present invention is not limited to the following examples. In addition, unless otherwise specified, "parts" and "%" in Examples and Comparative Examples represent "parts by mass" and "% by mass", respectively.
"Ink" shown below is an abbreviation for water-based gravure or flexographic ink.

(Glass-transition temperature)
For the glass transition temperature, the temperature at the maximum value of tan δ was measured using a dynamic viscoelasticity measuring device (DVA-200 manufactured by IT Keisoku Co., Ltd.). Measurement conditions are shown below.
Measurement sample: Dried resin film with a film thickness of 150 μm Measurement temperature range: -90 to 200 ° C
Temperature rise: 5°C/min Measurement frequency: 10Hz

(Weight average molecular weight)
The weight average molecular weight is a polystyrene-equivalent value measured by GPC (gel permeation chromatography). The dried water-based polyurethane resin is dissolved in tetrahydrofuran to prepare a 0.1% solution, and the weight average molecular weight is determined by Tosoh HLC-8320-GPC (column number M-0053 molecular weight measurement range of about 2,000 to about 4,000,000). was measured.

(hydroxyl value and acid value)
It was determined according to the method described in JISK0070.

<Synthesis of water-based polyurethane resin>
(Comparative Synthesis Example 7)
PC(HD)2000 (a number containing 1,6-hexanediol "HD" component) was run while introducing nitrogen gas in a reactor equipped with a reflux condenser, dropping funnel, gas inlet tube, stirrer, and thermometer. Polycarbonate diol having an average molecular weight of 2000 (solid at 25° C.) 235.7 parts, 2,2-dimethylolpropionic acid (DMPA) 30.0 parts, and methyl ethyl ketone (MEK) 250 parts are mixed and stirred while isophorone diisocyanate (IPDI) Add 91.6 parts dropwise over 1 hour, react at 80° C. for 4 hours to obtain a terminal isocyanate prepolymer, then cool to 30° C. and add 100 parts of isopropyl alcohol to obtain a solvent solution of the terminal isocyanate prepolymer. Obtained. A mixture of 2.7 parts of 2-aminoethylethanolamine (AEA) and 150 parts of isopropyl alcohol (IPA) was gradually added to the resulting isocyanate-terminated prepolymer at room temperature and reacted at 40° C. for 2 hours. to obtain a solvent type polyurethane resin solution. Next, 13.6 parts of 28% aqueous ammonia and 1,080 parts of ion-exchanged water are gradually added to the above solvent-type polyurethane resin solution to neutralize it, and the methyl ethyl ketone and isopropyl alcohol are distilled off under reduced pressure. Water is added to adjust the solid content, and the acid value is 35 mg KOH / g, the hydroxyl value is 4.1 mg KOH / g, the glass transition temperature is -22 ° C., and the weight average molecular weight is 30,000. ) to obtain an aqueous solution.

(Synthesis Examples 1 to 13 and Comparative Synthesis Examples 1 to 6 and 8)
Aqueous polyurethane resins P1 to P13 and comparative aqueous polyurethane resins PP1 to PP6 and PP8 were synthesized in the same manner as in Comparative Synthesis Example 7 except that the raw material compounds shown in Table 1 were used.
In addition, the abbreviations of the raw material compounds in Table 1 indicate the following compounds, respectively.

(Diol Constituting Aliphatic Polycarbonate Diol)
PD: 1,5-pentanediol MPD: 3-methyl-1,5-pentanediol NPG: neopentyl glycol BD: 1,4-butanediol

(aliphatic polycarbonate diol)
PC (MPD/HD = 9/1) 2000: polycarbonate diol with a number average molecular weight of 2000 in which the above diol ratio MPD/HD is 9/1 PC (MPD/HD = 5/5) 2000: above diol Polycarbonate diol with a number average molecular weight of 2000 with a ratio MPD/HD of 5/5 Liquid PC at 25° C. (MPD/HD=7/3) 2000:number average molecular weight with a ratio MPD/HD of 7/3 2000 PC liquid at 25°C (HD/PD = 5/5) 2000: Polycarbonate diol with a number average molecular weight of 2000 with the above diol ratio HD/PD of 5/5 Liquid PC at 25°C (BD/NPG = 5/5) 2000: Polycarbonate diol with a number average molecular weight of 2000 in which the above diol ratio BD/NPG is 5/5 PEG2000: Polyethylene glycol with a number average molecular weight of 2000 PTG2000: Polytetramethylene glycol with a number average molecular weight of 2000 PMPA2000: Poly(3-methyl-1,5-pentaneadipate) diol with a number average molecular weight of 2000 UC-100: Polycarbonate diol with a number average molecular weight of 1000 having a cyclic diol as a main skeleton manufactured by Ube Industries, Ltd. Solid at 25°C
DMBA: dimethylolbutanoic acid DMPA: dimethylolpropionic acid

(Properties of water-based polyurethane resin)
Table 1 shows the acid value (mgKOH/g), the hydroxyl value (mgKOH/g), the amount of polyethylene glycol in the aqueous polyurethane resin solid content (composition) of the aqueous polyurethane resins P1 to P13 (examples) and PP1 to PP8 (comparative examples). (% by mass of unit), amount of polycarbonate in solid content (% by mass of structural unit), glass transition temperature (° C.), and weight average molecular weight are shown.

(Comparative Example 7) (Production of Ink T7)
Copper phthalocyanine indigo (indigo pigment C.I. Pigment Blue 15:3 manufactured by Toyocolor Co., Ltd.) 15 parts, polyurethane resin PP7 aqueous solution 30 parts, antifoaming agent 0.1 part, adipic acid dihydrazide (ADH) 0.2 parts, n - 5 parts of propanol and 19.7 parts of water were stirred and mixed and dispersed for 20 minutes in a sand mill, which is a bead mill, and then 20 parts of an aqueous solution of polyurethane resin P1, 5 parts of n-propanol and 5 parts of water were stirred and mixed to obtain Ink T7. rice field. (Table 2 shows the total amount of each component.)

Comparative Example 7 of printed matter, laminate and packaging bag using ink T7 is shown below.

(Preparation of printed matter for laminate using ink T7) (OPP base material)
Gravure printing: Ink T7 obtained above is adjusted to 16 seconds using a mixed solvent of water/n-propanol mixed solvent (mass ratio 1/1) with Zahn cup #3 (manufactured by Rigosha). Then, using a gravure printing machine manufactured by Iwase Printing Machine Co., Ltd., a plastic substrate (polypropylene (OPP) substrate P-2161 film thickness 20 μm) was printed at a speed of 50 m / min and dried at 60 ° C. to obtain a printed matter. . The plate used was a 250-line corrosion solid plate with a depth of 15 μm.
(Preparation of laminate using ink T7)
After applying an isocyanate-based anchor coating agent (EL557A/B, manufactured by Toyo-Morton Co., Ltd.) on the printed layer of the OPP printed matter, the low-density polyethylene is melted and extruded, and a plastic substrate (unstretched polyethylene ( LLDPE) base material (TUX-FCD film thickness 40 μm) and laminated to obtain a laminate. Laminate strength evaluation was performed using this laminate.

(Preparation of printed material for packaging bag using ink T7) (PET base material)
A printed matter was prepared in the same manner as described above, except that a polyethylene terephthalate (PET) base material (polyester base material E5100, thickness 12 μm) was used instead of the OPP base material.
(Creation of packaging bag using ink T7)
TM250-HV manufactured by Toyo-Morton Co., Ltd. is applied as a urethane-based adhesive onto the printed layer of the PET printed matter at 2 g/m ² , and laminated with an aluminum foil substrate (manufactured by Toyo Aluminum Co., Ltd., film thickness 7 μm). A laminate was obtained by laminating with ZK-207 (manufactured by Toray Industries, Inc., unstretched polypropylene substrate, thickness 60 μm). The edges of the unstretched polypropylene surfaces of this laminate were heat-sealed at 190° C. to form a bag to obtain a packaging bag. The content was water. Using this packaging bag, the following light resistance and retort resistance tests were performed.

(Examples 1 to 16) (Inks S1 to S16)
Inks S1 to S16 (Examples), their printed materials, laminates, and packaging bags were obtained in the same manner as in T7, except that the inks and compositions shown in Table 2 were used.

(Comparative Examples 1 to 6, 8) (Inks T1 to T6, T8)
Inks T1 to T6, T8 (comparative example), its printed matter, laminate and packaging bag were obtained in the same manner as for T7, except that the inks and compositions shown in Table 2 were used.

[Characteristic evaluation]
Using the above inks S1 to S16 (Examples) and T1 to T8 (Comparative Examples) and printed matter, laminates and packaging bags using them, the following specific evaluations were carried out, and the results are shown in Table 2. In the table, *1 in Comparative Example 3 represents the following.
*1: The dispersion state of the ink was poor and it was impossible to evaluate.

[Laminate strength]
Laminates using S1 to S16 (Examples) and T1 to T8 (Comparative Examples) were cut to a width of 15 mm, and the peel strength when peeled between the ink surface and the molten resin layer was measured using Intesco 201 Universal Tensile. It was measured using a testing machine. Evaluation criteria are shown below. The practical level is 3-5.
5: Peel strength of 1.0 N/15 mm or more 4: Peel strength of 0.7 N/15 mm or more and less than 1.0 N/15 mm 3: Peel strength of 0.5 N/15 mm or more and 0.7 N/15 mm Less than 2: Peel strength is 0.3 N / 15 mm or more and less than 0.5 N / 15 mm 1: Peel strength is less than 0.3 N / 15 mm

[Lightfastness]
The packaging bags using S1 to S16 (examples) and T1 to T8 (comparative examples) were irradiated with ultraviolet rays for 6 hours and 12 hours using an ultraviolet autofedometer (manufactured by Suga Test Instruments Co., Ltd., model: UA48AUHB). The laminate strength after irradiation was measured, and the laminate strength before and after irradiation was compared. Evaluation criteria are shown below. The practical level is 3-5.
5: No decrease in peel strength was observed before and after irradiation with ultraviolet rays, and the peel strength after irradiation was 2.0 N/15 mm or more. 2. The peel strength after irradiation is 2.0 N/15 mm or more 3: A decrease in peel strength of 1.0 N/15 mm or more is observed before and after UV irradiation, but the peel strength after irradiation is 1.0 N/15 mm or more; Less than 0 N / 15 mm 2: A decrease in peel strength of 1.0 N / 15 mm or more is observed before and after ultraviolet irradiation, and the peel strength after irradiation is 0.5 N / 15 mm or more and less than 1.0 N / 15 mm 1: Ultraviolet A decrease in peel strength of 1.0 N/15 mm or more is observed before and after irradiation, and the peel strength after irradiation is less than 0.5 N/15 mm

[Retort resistance suitability]
The packaging bags using S1 to S16 (Examples) and T1 to T8 (Comparative Examples) were subjected to a retort test at 120°C for 80 minutes, and the laminate strength immediately after retort was compared with the laminate strength before the retort test. Evaluation criteria are shown below. The practical level is 3-5.
5: No decrease in peel strength was observed before and after retorting, and the peel strength after retort was 2.0 N/15 mm or more. Peel strength of 2.0 N / 15 mm or more 3: A decrease in peel strength of 1.0 N / 15 mm or more is observed before and after retort, but the peel strength after retort is 1.0 N / 15 mm or more, 2.0 N / 15 mm Less than 2: A decrease in peel strength of 1.0 N/15 mm or more is observed before and after retorting, and the peel strength after retorting is 0.5 N/15 mm or more and less than 1.0 N/15 mm 1: 1.0 N/15 mm or more before and after retorting A decrease in peel strength of 0 N/15 mm or more is observed, and the peel strength after retort is less than 0.5 N/15 mm

[Diluted ink stability]
The viscosity of the diluted ink for gravure printing adjusted to 16 seconds with Zahn cup #3 was measured after storage at 40° C. for 7 days, and the degree of thickening was measured according to the following evaluation criteria.
5: No increase in viscosity 4: Increase in viscosity within 2 seconds 3: Increase in viscosity within 5 seconds 2: Increase in viscosity within 10 seconds 1: Significant increase in viscosity, viscosity cannot be measured

The inks of Examples 1 to 16 are superior in light resistance after 12 hours of UV irradiation compared to the inks of Comparative Examples 1 to 8, and provide excellent inks with practical levels of lamination strength and retort resistance. was made.

As shown above, in the examples, it was confirmed that inks with blocking resistance, water resistance, and lamination strength all at or above practical levels were obtained, and that the inks were suitable for printing on plastic substrates. did it. On the other hand, the inks of the comparative examples did not have sufficient lightfastness after 12 hours of ultraviolet irradiation, or had no retort resistance.

[Example 17] (Evaluation by flexographic printing)
A printed matter related to ink S1 was printed in the same manner as in Example 1 except that printing was performed by a flexographic printing method using a flexographic printing machine equipped with a flexographic plate (photosensitive resin plate, plate thickness 1 mm, plate line number 150 lines) and an anilox roll. A laminate and a packaging bag were obtained. Furthermore, when the same characteristic evaluation as described above was performed, the evaluation results were the same as in Example 1 above.

Claims (7)

A water-based gravure or flexographic ink for lamination containing a water-based polyurethane resin, comprising:
The aqueous polyurethane resin has a glass transition temperature of −40 to 0° C., a hydroxyl value of 0.1 to 15 mgKOH/g, and an acid value of 15 to 60 mgKOH/g.
and the aqueous polyurethane resin contains structural units derived from an aliphatic polycarbonate polyol, and the aliphatic polycarbonate polyol is liquid at 25°C.
Water-based gravure or flexo ink. 2. The water-based gravure or flexographic ink according to claim 1, wherein said aliphatic polycarbonate polyol contains structural units derived from branched diols having tertiary and/or quaternary carbons. 3. The water-based gravure or flexographic ink according to claim 2, wherein the aliphatic polycarbonate polyol has a branched diol having tertiary carbon and/or quaternary carbon and an aliphatic diol having a linear structure as structural units. The mass ratio of the branched diol having a tertiary carbon and/or a quaternary carbon and the aliphatic diol having a linear structure (the former: the latter) is 95:5 to 30:70 according to claim 3. Water-based gravure or flexo ink. 5. The water-based gravure or flexographic ink according to claim 1, wherein the water-based polyurethane resin contains 2 to 30% by mass of polyethylene glycol-derived structural units in the total weight of the water-based polyurethane resin. A printed matter having a print layer formed of the water-based gravure or flexo ink according to any one of claims 1 to 5 on a substrate 1. A laminate having an adhesive layer and a base material 2 in this order on the printed layer of the printed matter according to claim 6 .