JP7205246B2 - Aqueous gravure ink and its use - Google Patents

Description

The present invention relates to aqueous gravure inks using natural dyes.

In order to solve problems such as environmental conservation, compliance with laws and regulations, and improvement of working environments such as printing, conversion of organic solvent-based printing inks to water-based printing inks has been proposed. Since water-based printing ink uses water as a medium, it is difficult to dry during the printing process. It was widely used for printing on paper substrates such as cardboard. Water-based printing inks are also recommended for water-based gravure inks used in the field of plastic packages, mainly packaging applications, and water-based printing inks that are compatible with impermeable plastic substrates are expected.

On the other hand, there is growing interest in carbon-neutral printed matter, and there is a movement to conserve the environment by converting the components that make up printing inks into biomass, as well as flexible packaging materials, including base materials and adhesives, into biomass. Be active.

For example, Patent Document 1 discloses a water-based gravure printing ink composed of a synthetic pigment using a petroleum-based material and a binder resin using a petroleum-based material. Since the ink on the plate is not sufficiently re-dissolvable during printing, there is also a problem that plate clogging is likely to occur and printing defects are often caused. In addition, it does not achieve carbon neutrality by converting to biomass, which is expected for ink from the viewpoint of environmental conservation.

In addition, as a biomass ink, Patent Document 2 discloses a technique for providing a gravure ink using a urethane resin made from plant-derived castor oil. Compared to urethane resins made from polyols, its solubility in ester solvents is inferior, and the resolubility of the ink on the plate during printing is insufficient. There is also a problem. In addition, since a synthetic pigment made from a petroleum raw material is used as a pigment component, the biomass degree of the dried ink film is less than 20% by mass, which does not sufficiently contribute to carbon neutrality due to conversion to biomass.

As a dye-based water-based gravure ink, Patent Document 3 discloses a printing ink using a dye. However, since this printing ink is used for textile printing, it does not contain a binder that can adhere the ink to impermeable plastic substrates other than textile materials. It cannot be used for inks with

Thus, no water-based gravure ink has been known which has excellent printability on impermeable plastic substrates and which has a natural dye as a coloring agent.

JP 2015-067818 A JP 2018-109131 A JP 2017-2266 A

An object of the present invention is to provide a water-based gravure ink containing a biomass-derived component that can be applied to impermeable plastic substrates and has good printability.

As a result of intensive studies on the above problems, the inventors of the present invention have found that the above problems can be solved by using the water-based gravure ink described below, and have completed the present invention.

That is, the present invention relates to an aqueous gravure ink containing a natural dye (A) and an aqueous binder resin (B), and having a biomass content of 40% by mass or more in the total mass of non-volatile components of the ink.

The present invention also relates to the aqueous gravure ink, wherein the aqueous binder resin (B) contains an aqueous polyurethane resin (B1) and/or an aqueous vinyl resin (B2).

The present invention also relates to any one of the water-based gravure inks described above, wherein the water-based polyurethane resin (B1) has a structure derived from sebacic acid and/or succinic acid.

The present invention also relates to any one of the water-based gravure inks described above, wherein the natural dye (A) contains a dye derived from Benicouji.

The present invention also relates to a printed material comprising a base material and a printed layer formed of any of the water-based gravure inks described above.

INDUSTRIAL APPLICABILITY According to the present invention, it was possible to provide a water-based gravure ink containing a biomass-derived component that can be applied to impermeable plastic substrates and has good printability.

Embodiments of the present invention will be described in detail below, but the description of the constituent elements described below is an example (representative example) of embodiments of the present invention, and the present invention does not exceed the gist thereof. Content is not limited.

In the following description, "aqueous gravure ink" may be referred to as "ink" or "ink composition", but they have the same meaning. In the following description, non-volatile components refer to components other than volatile components such as water and organic solvents in the composition, and the printing layer of water-based gravure ink consists of non-volatile components in water-based gravure ink. The printed layer is sometimes called an "ink layer" or an "ink film", but they are synonymous.

In the following description, the degree of biomass refers to the mass ratio composed of components of plant-derived, biological-derived and other non-petroleum-derived compounds.

TECHNICAL FIELD The present invention relates to a water-based gravure ink containing a natural dye (A) and a water-based binder resin (B), which has excellent printability and has a biomass content of 40% by mass or more in the non-volatile components of the ink. Here, the natural dye (A) functions as a coloring material, and by using the water-based binder resin (B) described below, the re-solubility and dispersibility of the ink are improved compared to when a pigment is used. As a result, excellent substrate transferability to impermeable plastic substrates and the effect of suppressing plate fogging can be obtained.

<Natural dye (A)>
The natural dyes (A) used in the present invention are not limited to the following examples, but for example, dyes extracted from natural substances customarily used as foods are preferable, and carotenoid-based gardenia yellow dyes (crocin, crocetin), atner pigments (bixin, norbixin), paprika extract pigments (capsanthin), carrot pigments (β-carotene), tomato pigments (lycopene), marigold pigments (carotenoids, flavonoids), β-apo 8-carotenal, canthaxanthin , red pepper pigment, flavonoid pigment, onion pigment, shea nut pigment, pecan nut pigment, chicory pigment, chalcone safflower yellow pigment (safromine), safflower red pigment (carthamine), anthocyanin perilla pigment (shisonin, malonylshisonin), Red cabbage pigment (cyanidin acyl glycoside), red radish pigment (pelargonidin acyl glycoside), purple sweet potato pigment (cyanidin acyl glucoside, peonidin acyl glucoside), purple corn pigment, grape skin pigment (enocyanin), elderberry pigment (cyanidin glycoside) , delphinidin glycoside), grape juice pigment, blueberry pigment, hibiscus pigment, flavone-based cocoa pigment, persimmon pigment (flavonoid), tamarind pigment, sorghum pigment (apigeninidin, luteolinidin), flavonol-based carob pigment, licorice extract pigment, porphyrin-based Chlorophyll, anthraquinone-based cochineal pigment (carminic acid), lac pigment (laccaic acid), madder pigment (alizarin, rubritric acid), other, turmeric pigment (curcumin), red yeast yellow pigment (xanthomonasin), red yeast pigment (monas) colubrin, ankaflavin), gardenia pigment, beetlet (betaine betanin, isobetanin), copper chlorophyllin sodium, gardenia blue pigment, spirulina pigment (phycocyanin), vegetable charcoal powder pigment, caramel pigment, etc. Pigments that are dyes are preferred. The content of the dye (chromogen) in the ink varies depending on the shade of the desired color pattern and is not particularly limited. 70% by mass is even more preferable. This is because the color developability and adhesion to plastic substrates are improved.

<Aqueous binder resin (B)>
In the present invention, the water-based binder resin (B) refers to the main resin component in the ink. The water-based binder resin (B) is preferably a water-soluble or emulsion-like resin. (B1), water-based vinyl resins (B2), water-based polyester resins, water-based polyamide resins, water-based rosin resins, and the like can be suitably used. Furthermore, from the viewpoint of adhesion to plastic substrates when the natural dye (A) is used in combination, it is preferable to contain an aqueous polyurethane resin (B1) and/or an aqueous vinyl resin (B2). These resins are preferably contained in an amount of 70 to 100% by mass in the total mass of the binder resin.
The content of the water-based binder resin (B) in the ink film is preferably 10% by mass to 80% by mass, more preferably 40% by mass to 40% by mass, of the entire ink film, from the viewpoint of adhesion to plastic substrates and dye color development. 60% by mass is more preferred.

(Aqueous polyurethane resin (B1))
The weight average molecular weight of the water-based polyurethane resin (B1) in the present invention is preferably within the range of 5,000 to 100,000. A weight average molecular weight is a polystyrene conversion value measured by GPC. When the weight-average molecular weight is 5,000 to 100,000, there is an effect of improving adhesion to plastic substrates. Further, the obtained water-based printing ink has a suitable viscosity, so that the solubility in a water-alcohol mixed solvent is improved, and the re-solubility of the ink tends to be good. The acid value (acid value before neutralization) is preferably 10 to 60 mgKOH/g, more preferably 25 to 45 mgKOH/g. This is because the solubility in an aqueous medium or a medium consisting of a mixed solvent of water and alcohol is improved, and the re-solubility and light resistance of the ink are improved.

The water-based polyurethane resin used in the present invention is not limited by its manufacturing method, but is, for example, a water-based polyurethane resin obtained by reacting polyisocyanate, hydroxy acid and polyol (excluding hydroxy acid). preferably
It is also preferable to use an aqueous polyurethane resin obtained by reacting a urethane prepolymer obtained by reacting a polyisocyanate, a hydroxy acid and a polyol (excluding the hydroxy acid) with a polyamine.

(polyisocyanate)
As the polyisocyanate, 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, pentamethylene diisocyanate, hexamethylene 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)cyclohexane, methylcyclohexane Typical examples include 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. Aliphatic or alicyclic polyisocyanates are preferably used because of improved weather resistance, and polyisocyanates selected from pentamethylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, and cyclohexane-1,4-diisocyanate are preferably used as raw materials. .

(hydroxy acid)
Among the above hydroxy acids, the functional group constituting the acid includes acidic functional groups such as sulfonic acid (sulfone group) and carboxylic acid (carboxyl group), and carboxylic acid is preferred. The hydroxy acid is not limited to the following, but is preferably dimethylolalkanoic acid such as 2,2-dimethylolpropanoic acid, 2,2-dimethylolbutanoic acid, 2,2-dimethylolpentanoic acid, and the like. These can be used alone or in combination of two or more. Hydroxy acids generally leave most of the acidic functional groups unreacted in the reaction with polyisocyanate, allowing the water-based polyurethane resin to contain a predetermined acid value.

(polyol)
By using a polyester polyol, a polyether polyol, a polycarbonate polyol, or the like as the above polyol, it is possible to make the water-based polyurethane resin (B1) contain structural units derived from the corresponding polyol. The polyol preferably contains a polyether polyol and/or a polyester polyol among others. It is more preferable to contain a polyester polyol, because the use of a polyester polyol improves adhesion to plastic substrates, as well as re-solubility and plate fogging during printing.

The above polyester polyol is preferably a polyester polyol comprising a condensate of a polybasic acid and a low-molecular-weight polyol.

The above polybasic acid is preferably a dibasic acid, such as adipic acid, phthalic acid, isophthalic acid, terephthalic acid, maleic acid, fumaric acid, succinic acid, oxalic acid, malonic acid, glutaric acid, pimelic acid, and spelline. Preferred examples include acids, azelaic acid, sebacic acid, trimellitic acid, pyromellitic acid, 2,5-furandicarboxylic acid and the like.
The use of succinic acid, sebacic acid, adipic acid, bio-2,5-furandicarboxylic acid and the like is preferred. Among them, it is more preferable to use succinic acid and/or sebacic acid, and it is preferable to contain structural units derived from succinic acid and/or sebacic acid. The structural unit derived from succinic acid and/or sebacic acid is preferably contained in the aqueous polyurethane resin (B1) in an amount of 10 to 40% by mass, more preferably 15 to 35% by mass, more preferably 20 to 35% by mass. is more preferred.
Raw materials such as succinic acid and/or sebacic acid are called biomass raw materials, and are preferable from the viewpoint of environmental conservation. Since it is possible to increase the biomass content by suitably using a biomass raw material, the biomass content of the aqueous polyurethane resin (B1) is preferably 30% by mass or more based on the total amount of the aqueous polyurethane resin (B1), and is preferably 50 mass%. % or more is more preferable.

The low-molecular-weight polyol is preferably a low-molecular-weight diol, such as ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, diethylene glycol, triethylene. Glycol and the like are preferably mentioned. More preferably, it is a low-molecular-weight diol having a branched structure, and the low-molecular-weight diol having a branched structure refers to a diol in which at least one hydrogen of alkylene glycol is substituted with an alkyl group or the like. For example, 1,2-propanediol, 1,3-butanediol, 2-methyl-1,3-propanediol, neopentyl glycol, 1,4-pentanediol, 3-methyl-1,5-pentanediol, 2 ,5-hexanediol, 2-methyl-1,4-pentanediol, 2,4-diethyl-1,5-pentanediol, 2-butyl-2-ethyl-1,3-propanediol, 2-methyl-1 ,8-octanediol, 2,2,4-trimethyl-1,3-pentanediol, 2,2,4-trimethyl-1,6-hexanediol, and dipropylene glycol. This is because the adhesiveness to the film, the re-dissolving property, and the plate fogging property can be further improved.
Moreover, the polyester polyol is preferably a polyester polyol composed of a dibasic acid and a low-molecular-weight diol having a branched structure, in terms of adhesion to films and printability.
Furthermore, it is preferable to contain low-molecular-weight polyols having two or more hydroxyl groups and having a branched structure. Suitable low-molecular-weight polyols include glycerin, trimethylolpropane, trimethylolethane, and the like.

Polyether polyols include polyethylene glycol, polypropylene glycol, polytrimethylene glycol, and polytetramethylene glycol, which are polymers or copolymers of methylene oxide, ethylene oxide, propylene oxide, tetrahydrofuran, and co-polymers thereof. Polyether polyols composed of polymers are suitable. In particular, it is preferable to use polyethylene glycol as a raw material. This is because when polyethylene glycol is used, re-solubility in an aqueous medium or a medium consisting of a mixed solvent of water and alcohol is improved.

Also, the polyol preferably contains a low-molecular-weight diol selected from ethylene glycol, 1,3-propanediol, and 1,4-butanediol. Among these, it is more preferable to contain 1,3-propanediol. As a form containing such a low-molecular-weight diol, when it is contained as a structural unit in a polyester polyol or other polyol as described above, or when it is contained as a structural unit in an aqueous polyurethane resin (B1) (contained as a structural unit in a polyol except for the case). The low-molecular-weight diol is preferably derived from biomass from the viewpoint of environmental conservation.

The above-mentioned polycarbonate polyol refers to a polyol mainly having a carbonate ester linking group, and is not limited by the production method. can be obtained by the reaction of These can be used alone or in combination of two or more.

Furthermore, a monoalcohol may be used as a polymerization terminator to prevent overreaction in the urethanization reaction as long as it is in the range of 0% by mass to 30% by mass in the polyol. Examples include methanol, ethanol, propanol, n-butanol and the like.

The polyol used in the aqueous polyurethane resin (B1) in the present invention preferably has a number average molecular weight of 500 to 5,000. The number average molecular weight is calculated from the hydroxyl value, and the hydroxyl value is calculated by esterifying or acetylating the hydroxyl groups in the resin and back titrating the remaining acid with an alkali. It is a value converted into mg of potassium oxide and is a value obtained according to JISK0070. When the number average molecular weight is 500 to 5000, the carboxyl groups incorporated for water solubility can be scattered in the aqueous polyurethane resin, so resolubility in aqueous media and media consisting of mixed solvents of water and alcohol is improved. do. The number average molecular weight is more preferably 1000-3000.

(polyamine)
Polyamines that can be used as a constituent component of the aqueous polyurethane resin (B1) in the present invention include, for example, 2-hydroxyethylethylenediamine, 2-hydroxyethylpropylenediamine, di-2-hydroxyethylethylenediamine, and di-2-hydroxyethylpropylene. diamines, diamines having hydroxyl groups such as 2-hydroxypropylethylenediamine and di-2-hydroxypropylethylenediamine, ethylenediamine, propylenediamine, hexamethylenediamine, isophoronediamine, dicyclohexylmethane-4,4'-diamine, and carboxyl groups of dimer acids is converted to an amino group such as dimerdiamine, and amino acids such as glutamine, asparagine, lysine, diaminopropionic acid, ornithine, diaminobenzoic acid and diaminobenzenesulfonic acid. These can be used alone or in combination of two or more. A diamine having a hydroxyl group is preferred. This is because resolubility and printability in an aqueous medium or a medium comprising a mixed solvent of water and alcohol tend to be good.

(Production of water-based polyurethane resin (B1))
The water-based polyurethane resin (B1) in the present invention is synthesized using an organic solvent (eg, acetone or methyl ethyl ketone) that is inert to isocyanate and hydrophilic, and after adding water, the organic solvent is added. It can be obtained by an acetone method in which the solvent is distilled off under reduced pressure, or by a non-solvent synthesis method in which the organic solvent is not used at all. In the present invention, it is desirable to use the acetone method, in which an organic solvent is used to lower the viscosity and the synthesis reaction can be carried out uniformly and smoothly.

As a synthesis procedure, polyisocyanate, hydroxy acid and polyol are reacted to produce a urethane prepolymer having an isocyanate group at the end (hereinafter also referred to as a prepolymer reaction), and if necessary, a chain extension reaction is performed with polyamine. It is preferable to The prepolymer reaction is preferably carried out at 50-100° C. for 10 minutes-10 hours. The end point of the reaction is judged by viscosity measurement, NCO peak by IR measurement, NCO % measurement by titration, and the like. The chain extension reaction is preferably carried out at 20-80° C. for 10 minutes-10 hours. The end point of the reaction is judged by viscosity measurement, NCO peak by IR measurement, amine value measurement by titration, and the like.

A catalyst can also be used for the prepolymer reaction. Usable catalysts include known metal-based catalysts and amine-based catalysts. Metal catalysts include dibutyltin dilaurate, tin octoate, dibutyltin di(2-ethylhexoate), lead 2-ethylhexoate, 2-ethylhexyl titanate, iron 2-ethylhexoate, 2- Cobalt ethylhexoate, zinc naphthenate, cobalt naphthenate, tetra-n-butyltin and the like. Examples of the amine catalyst include tertiary amines such as tetramethylbutanediamine. These catalysts are used in the range of 0.001 to 1 mol % with respect to the polymer polyol.

A reaction terminator may be used in the chain extension reaction for the purpose of suppressing an excessive increase in molecular weight. Examples of such a reaction terminator include dialkylamines such as di-n-butylamine, monoethanolamine, diethanolamine, 2-amino-2-methyl-1-propanol, tri(hydroxymethyl)aminomethane, 2- Amines having a hydroxyl group such as amino-2-ethyl-1,3-propanediol can also be used. Furthermore, monoamine amino acids such as glycine, alanine, glutamic acid, taurine, aspartic acid, aminobutyric acid, valine, aminocaproic acid, aminobenzoic acid, aminoisophthalic acid, and sulfamic acid are also included.

Neutralizing the carboxyl groups of the aqueous polyurethane resin (B1) with a basic compound has the effect of improving the water solubility of the aqueous polyurethane resin (B1), and as a result, the printability of the ink is improved. Examples of the basic compound include ammonia, monoethylamine, diethylamine, trimethylamine, triethylamine, triisopropylamine, tributylamine, triethanolamine, methyldiethanolamine, monoethanolamine, dimethylethanolamine, diethylethanolamine, morpholine, and N-methylmorpholine. , 2-amino-2-methyl-1-propanol, and other organic amines; sodium hydroxide, potassium hydroxide, and other inorganic alkalis; From the viewpoints of water resistance, residual odor, etc., preferred are highly volatile substances that are water-soluble and can be easily eliminated by heat during drying, and ammonia is particularly preferred.

As the organic solvent used for synthesizing the water-based polyurethane resin (B1) in the present invention, an organic solvent that is inert to isocyanate and hydrophilic is preferred. Examples include ethers such as tetrahydrofuran and dioxane, esters such as ethyl acetate, ketones such as acetone, methyl ethyl ketone and cyclohexanone, and amides such as dimethylformamide and N-methylpyrrolidone. It is preferable to use a solvent having a boiling point lower than that of water because it can be removed by distillation (removing the solvent) and also because the drying speed can be increased even when the solvent is used without removing the solvent. When the solvent is removed, for example, after adding water and a basic compound as a neutralizing agent to the reaction solution, the temperature is raised and the required amount of the solvent is distilled off under normal pressure or under reduced pressure. .

In the following description, "(meth)acryl" means "methacryl and/or acryl".

(Aqueous vinyl resin (B2))
The water-based vinyl resin (B2) in the present invention refers to a water-based resin obtained by polymerizing a vinyl compound as a monomer, and may be water-soluble or an aqueous emulsion. Examples of polymerization methods include radical polymerization, anionic polymerization, and cationic polymerization. The water-based vinyl resin (B2) is preferably a linear polymer compound, preferably a thermoplastic resin. Suitable vinyl resins include polystyrene resins, acrylic resins, styrene-acrylic copolymer resins, styrene-maleic acid copolymer resins, and modified resins thereof. The water-based vinyl resin (B2) preferably has a neutralized acid value of 30 to 500 mgKOH/g, more preferably 50 to 300 mgKOH/g.
At least one selected from (meth)acrylic acid esters, styrene-based monomers, and acidic monomers is preferably used as the monomer constituting the vinyl-based resin.

(monomer)
The (meth)acrylic acid ester constituting the water-based vinyl resin (B2) includes, for example, methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, ( meth)butyl acrylate, isobutyl (meth)acrylate, octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, (meth)acrylic acid 2 -hydroxyethyl, 2-hydroxypropyl (meth)acrylate, 2-(dimethylamino)ethyl (meth)acrylate, 2-(diethylamino)ethyl (meth)acrylate, 2-methoxy (meth)acrylate Preferred examples include ethyl, 2-butoxyethyl (meth)acrylate, glycidyl (meth)acrylate and the like.
Styrene-based monomers constituting the aqueous vinyl-based resin (B2) preferably include styrene, α-methylstyrene, styrene derivatives, and the like.
Acidic monomers constituting the water-based vinyl resin (B2) include, for example, phthalic acid monohydroxyethyl (meth)acrylate, p-carboxybenzyl (meth)acrylate, ethylene oxide-modified (addition mole number: 2 to 18) phthalic acid ( monocarboxylic acid-containing monomers such as meth)acrylate, monohydroxypropyl (meth)acrylate phthalate, monohydroxyethyl (meth)acrylate succinate, β-carboxyethyl acrylate, 2-methacryloyloxyethylhexahydrophthalate, and , maleic acid, maleic anhydride, itaconic acid, citraconic acid, and fumaric acid. Among them, acrylic acid, methacrylic acid, maleic acid, maleic anhydride, itaconic acid, citraconic acid, fumaric acid and the like are preferable. These acidic monomers are partly or wholly neutralized after forming the vinyl-based resin and rendered water-based.

When the aqueous vinyl resin (B2) in the present invention is an aqueous emulsion, it can be obtained by a known emulsion polymerization method. A method of emulsion polymerization by charging the above monomers at once, a method of emulsion polymerization while continuously supplying each of the above monomers, a method of previously solution-polymerizing a part of the above monomers to form an oligomer, and adding other monomers in the resulting aqueous solution of the oligomer. Various methods such as a method of emulsion polymerization can be applied. As a polymerization aid for emulsion polymerization, an emulsifier, a polymerization initiator, a chain transfer agent such as mercaptans, a pH adjuster, and an antifoaming agent may be used.

Polymerization initiators used for polymerization of the above monomers include water-soluble types such as persulfates such as potassium persulfate and ammonium persulfate, hydrogen peroxide water, t-butyl hydroperoxide, hydrochloride of azobisamidinopropane, etc. Oil-soluble types such as benzoyl peroxide, cumene hydroperoxide, dibutyl peroxide, diisopropyl peroxydicarbonate, cumyl peroxyneodecanoate, cumyl peroxyoctoate, and azobisisobutyronitrile are exemplified. Furthermore, if necessary, a redox system using a reducing agent such as N,N-dimethylaniline, sodium acid sulfite, Rongalite, L-ascorbic acid, etc. can also be used. The amount of the polymerization initiator to be used is usually 0.01 to 5 parts by mass, more preferably 0.05 to 2 parts by mass, per 100 parts by mass of the total amount of the monomers.

The water-based vinyl resin (B2) has a pH is preferably adjusted to 6 to 11. Ammonia, ethylamine, diethylamine, triethylamine, ethanolamine, triethanolamine, dimethylethanolamine, sodium carbonate, potassium carbonate, sodium hydroxide, potassium hydroxide and the like can be suitably used as the adjusting agent for adjusting the pH.

(auxiliary resin)
In the water-based gravure ink of the present invention, an auxiliary resin can be used in combination with the binder resin (B), if necessary. Examples of resins used in combination include shellac, chlorinated polyolefin resins, and rosin-modified maleic acid resins. The combined resin can be used singly or in combination of two or more within a range that does not interfere with the object of the present invention.

(Other additives)
The aqueous gravure ink of the present invention may contain additives such as curing agents, antiblocking agents, thickeners, rheology modifiers, antifoaming agents, leveling agents, preservatives, surface tension modifiers, agents, pH adjusters, polyethylene particles, ultraviolet absorbers, and the like.

In the present invention, it is preferable to add an ultraviolet absorber in order to improve the durability of the natural dye (A). Many organic compounds and inorganic compounds are known as UV absorbers. -3,5-di-tert-amylphenyl)benzotriazole, 3-[3-(benzotriazol-2-yl)-5-tert-butyl-4-hydroxyphenyl]propionate of polyethylene glycol, and the like. .

(Manufacture of water-based gravure ink)
The aqueous gravure ink in the present invention can be produced by dissolving and/or dispersing the aqueous binder resin (B), the natural dye (A) and the like in an aqueous solution. Specifically, a natural dye is dissolved and/or dispersed in an aqueous solution with the aqueous binder resin (B) and the combined resin, and waxes, antifoaming agents, thickeners, curing agents, etc. are added to the resulting mixture. , a water-based gravure ink can be produced by blending other compounds.

A dispersing machine may be used when dispersion is required in the above mixing, and as such a dispersing machine, commonly used roller mills, ball mills, pebble mills, attritors, sand mills, etc. can be used. .

The ink viscosity of the water-based gravure ink produced by the above method is preferably 10 mPa s or more, more preferably 30 mPa s or more, from the viewpoint of preventing sedimentation of the dye and appropriately dispersing it. From the viewpoint of workability efficiency, it is preferably 1000 mPa·s or less, more preferably 500 mPa·s or less. The above viscosity is measured at 25° C. with a Brookfield viscometer.

The viscosity of the water-based gravure ink can be adjusted by appropriately selecting the types and amounts of raw materials used, such as polyurethane resins, colorants, aqueous solutions, and the like.

(Printing with water-based gravure ink)
The water-based gravure ink of the present invention can be printed on a plastic substrate or paper by a gravure printing method using a known gravure printing machine. When printing, it is diluted with an aqueous solution, such as ethyl alcohol, isopropyl alcohol, normal propyl alcohol, etc., diluted with a dilute solvent mixed with water to a viscosity and concentration suitable for the gravure printing method. They are mixed and supplied to each printing unit. Printing is performed by rotating an intaglio plate, scraping off excess ink with a doctor blade, and continuously transferring it to the substrate. The substrate is supplied by a winding method, and the printing speed is preferably 50 to 300 m/min.

(Base material)
A paper substrate or a plastic substrate may be used as the substrate that can be used to produce the printed matter of the present invention, and the plastic substrate can be preferably used. Examples of such substrates include polyolefins such as polyethylene and polypropylene, polyesters such as polyethylene terephthalate, polycarbonate and polylactic acid, polystyrene resins such as polystyrene, AS resins and ABS resins, nylon, polyamide, polyvinyl chloride, polyvinylidene chloride, and cellophane. , paper, aluminum, etc., or a film-like substrate made of a composite material thereof. In addition, a vapor deposition substrate obtained by vapor-depositing an inorganic compound such as silica, alumina, or aluminum on a polyethylene terephthalate or nylon film can also be used, and the vapor-deposited surface may be coated with polyvinyl alcohol or the like. The surface of the plastic substrate to be printed (the surface in contact with the printed layer) is preferably treated for easy adhesion, and the easy adhesion treatment includes, for example, corona discharge treatment, ultraviolet/ozone treatment, plasma treatment, and oxygen plasma treatment. , primer treatment, and the like. For example, in corona discharge treatment, hydroxyl groups, carboxyl groups, carbonyl groups, and the like appear on the substrate. Since hydrogen bonding can be used, the ink preferably contains a compound having a functional group such as a hydroxyl group or an amino group.

Usual paper, cardboard, etc. are used as the paper base material, and there is no particular specification for the film thickness, but for example, 0.2 mm to 1.0 mm and 20 to 150 g/m ² can be used, and the printing surface is corona treated. It's okay to be. In addition, the surface of the paper substrate may be vapor-deposited with metal such as aluminum for the purpose of imparting design, and the surface may be coated with acrylic resin, urethane resin, polyester resin, polyolefin resin, or other resins. may be applied, and further surface treatment such as corona treatment may be applied. Examples include coated paper and art paper.

A laminate laminate can be obtained by printing the water-based gravure ink of the present invention on a plastic substrate, and further laminating the above-described substrate onto the printed layer of the printed matter via an adhesive.
As the lamination method, 1) an extrusion lamination method in which a molten resin is laminated after applying an anchor coating agent on the printed layer of the obtained printed matter as necessary, 2) after applying an adhesive, if necessary A dry lamination method of drying and further laminating a plastic film on the adhesive layer may be used. Anchor coat agents (AC agents) include imine-based AC agents, isocyanate-based AC agents, polybutadiene-based AC agents, and titanium-based AC agents. Urethane-based laminate adhesives include polyether urethane-based laminate adhesives and polyester-based laminates. Adhesives and the like are included, and there are those containing organic solvents and those containing no solvents. Moreover, molten polyethylene etc. are mentioned as molten resin. As a method for manufacturing the laminate, for example, a normal extrusion laminate (extrusion laminate) is used to laminate a molten polyethylene resin on a printed layer via various anchor coating agents such as imine, isocyanate, polybutadiene, and titanium. ) method, the dry lamination method and non-solvent lamination method, in which a urethane-based adhesive is applied to the printed layer and a plastic film is laminated on it, and the direct lamination method, in which melted polypropylene is pressed directly onto the printed surface and laminated. It can be obtained by a known lamination process such as a method.

EXAMPLES The present invention will be described in detail below with reference to examples, but the following are examples of embodiments of the present invention, and the present invention is not limited to these examples. Parts and % represent parts by mass and % by mass, respectively, unless otherwise specified.

(hydroxyl value)
It was obtained according to JISK0070.
(acid value)
It was obtained according to JISK0070.

(Weight average molecular weight)
The weight-average molecular weight was obtained by measuring the molecular weight distribution using a GPC (gel permeation chromatography) device (HLC-8220 manufactured by Tosoh Corporation) and obtaining the converted molecular weight using polystyrene as a standard substance. Measurement conditions are shown below.
Column: The following columns were connected in series and used.
Guard column H _XL -H manufactured by Tosoh Corporation
TSKgelG5000H _XL manufactured by Tosoh Corporation
TSKgelG4000H _XL manufactured by Tosoh Corporation
TSKgelG3000H _XL manufactured by Tosoh Corporation
TSKgelG2000H _XL manufactured by Tosoh Corporation
Detector: RI (differential refractometer)
Measurement conditions: Column temperature 40°C
Eluent: Tetrahydrofuran Flow rate: 1.0 mL/min

(Biomass degree and mass% of structural units derived from sebacic acid)
In gas chromatography-mass spectrometry (GC/MS), a mass spectrometer was used to detect components separated by chromatography, and the components were qualitatively and quantitatively determined from mass information. GCMS-QP2010 manufactured by SHIMAZU was used for gas chromatography.

<Synthesis of Polyol>
[Polyester Polyol Synthesis Example E-1]
After purging a reaction vessel equipped with a stirrer, a dividing tube, a thermometer, a nitrogen blowing tube and a manhole with nitrogen gas, 2800 parts of sebacic acid (derived from castor oil) and 633 parts of 1,3-propanediol (derived from plant) and 865 parts of neopentyl glycol were charged and dissolved by heating to 130° C. in a nitrogen atmosphere. Then, 0.06 part of tetrabutoxytitanium was added, the temperature was raised to 230° C., and the reaction was allowed to proceed while distilling off the generated water until almost no water was distilled off. Heating and pressure reduction were continued until the acid value became 0.5 mgKOH/g or less while reducing the pressure to further distill off water. Polyester polyol E containing 63.1% structural units derived from sebacic acid, with a hydroxyl value of 51.0 mgKOH/g, a number average molecular weight of 2200, an acid value of 0.2 mgKOH/g, and a biomass degree of 82.2%. -1 was obtained.

<Synthesis Example 1> [Aqueous polyurethane resin P1]
While introducing nitrogen gas in a four-necked flask equipped with a thermometer, a stirrer, a reflux condenser and a nitrogen gas introduction tube, 143.9 parts of polyester polyol E-1 having a number average molecular weight of 2200 and a number average molecular weight of 2000 14.7 parts of polyethylene glycol (PEG2000), 1.0 part of 1,3-propanediol, 27.2 parts of 2,2-dimethylolbutanoic acid (DMBA), and 94.4 parts of isophorone diisocyanate were charged into methyl ethyl ketone (MEK). ) in 163 parts of ) for 6 hours to give a terminal isocyanate prepolymer, cooled to 40° C., and then 64 parts of MEK was added to obtain a solvent solution of a terminal isocyanate prepolymer. Next, a mixture of 13.35 parts of 2-hydroxyethylethylenediamine (AEA) and 34 parts of isopropyl alcohol (IPA) was gradually added to the resulting isocyanate-terminated prepolymer solution at room temperature and reacted at 50°C for 3 hours. to obtain a solvent type polyurethane resin solution. Next, 31.3 parts of 10% aqueous ammonia and 807 parts of deionized water are gradually added to the solvent-based polyurethane resin solution to neutralize it, and then the entire amount of MEK is distilled off under azeotropic conditions. After that, water was added to adjust the viscosity. An aqueous polyurethane resin (P1) containing 30.8% structural units was obtained. The aqueous polyurethane resin (P1) has structural units derived from polyester polyol and structural units derived from polyether polyol.

<Synthesis Example 2> [Aqueous polyurethane resin P2]
144.3 parts of PMPA2000 with a number average molecular weight of 2000 and polyethylene glycol with a number average molecular weight of 2000 (PEG2000 ), 0.63 parts of 1,4-butanediol, 27.2 parts of 2,2-dimethylolbutanoic acid (DMBA), and 94.4 parts of isophorone diisocyanate were charged in 163 parts of methyl ethyl ketone (MEK). for 6 hours to obtain a terminal isocyanate prepolymer, cooled to 40° C., and then 64 parts of MEK was added to obtain a solvent solution of a terminal isocyanate prepolymer. Next, a mixture of 13.35 parts of 2-hydroxyethylethylenediamine (AEA) and 34 parts of isopropyl alcohol (IPA) was gradually added to the resulting isocyanate-terminated prepolymer solution at room temperature and reacted at 50°C for 3 hours. to obtain a solvent type polyurethane resin solution. Next, 31.3 parts of 10% aqueous ammonia and 807 parts of deionized water were gradually added to the solvent-type polyurethane resin solution to neutralize it, and then the entire amount of MEK was distilled off under azeotropic conditions. After that, water is added to adjust the viscosity, and an aqueous polyurethane resin with an acid value of 35 mg KOH / g, a solid content of 24%, a viscosity of 2200 mPa s, a weight average molecular weight of 26000, and a biomass degree of 0% in the total resin mass excluding the solvent ( P2) was obtained. The aqueous polyurethane resin (P2) has structural units derived from polyester polyol and structural units derived from polyether polyol.

<Comparative Synthesis Example 1> [Organic solvent-based polyurethane resin PP1]
231.9 parts of polyester polyol E-1 having a number average molecular weight of 2200, 21.6 parts of 1,3 propanediol, and isophorone diisocyanate were placed in a four-necked flask equipped with a stirrer, thermometer, reflux condenser and nitrogen gas inlet tube. 108.4 parts of stannous 2-ethylhexylate, 0.04 parts of stannous 2-ethylhexylate and 79.0 parts of ethyl acetate were charged, reacted at 90° C. for 3 hours under nitrogen flow, added with 218.8 parts of ethyl acetate and cooled. 670.3 parts of a solvent solution of an isocyanate prepolymer were obtained. Then, 618.7 parts of the resulting terminal isocyanate prepolymer was gradually added to a mixture of 20.4 parts of isophoronediamine, 1.49 parts of di-n-butylamine, 349.3 parts of ethyl acetate and 160.8 parts of isopropyl alcohol at room temperature. and then reacted at 50° C. for 1 hour. Then, after adding 4.00 parts of isophorone diisocyanate to adjust the viscosity, the solid content was adjusted to 30% with a solvent in which ethyl acetate/isopropyl alcohol (hereinafter abbreviated as "IPA") was mixed at a mass ratio of 8/2. After adjustment, an organic solvent-based polyurethane resin (PP1) having a mass average molecular weight of 35,000 and a biomass degree of 54.6% in the total amount of the resin excluding the solvent was obtained.

Abbreviations of raw materials used in the above synthesis examples are shown.
PEG2000: polyethylene glycol (number average molecular weight 2000)
PMPA2000: Polyester diol composed of 3-methyl-1,5-pentanediol and adipic acid (number average molecular weight 2000)
DMBA: 2,2-dimethylolbutanoic acid IPDI: isophorone diisocyanate AEA: 2-hydroxyethylethylenediamine MEK: methyl ethyl ketone

[Aqueous acrylic emulsion]
In the following examples, commercially available PDX-7630a (aqueous emulsion, styrene-acrylic copolymer resin, acid value: 200 mgKOH/g, non-volatile content: 32%, manufactured by Johnson Polymer Co., Ltd.) was used as the water-based vinyl resin (B2).

(Example 1) [Preparation of ink S1]
10.7 parts of Super Monas P20000 (Benkoji pigment (manufactured by Yaegaki Fermentation Giken Co., Ltd.)), 44.5 parts of water-based polyurethane resin (P1), 22.4 parts of isopropyl alcohol, and 22.4 parts of water were stirred and mixed to obtain a natural dye. The water-based gravure ink (S1) used was obtained.

(Example 2) [Preparation of ink S2]
10.7 parts of Super Monas P20000 (Benkoji pigment (manufactured by Yaegaki Fermentation Giken Co., Ltd.)), 44.5 parts of water-based polyurethane resin (P2), 22.4 parts of isopropyl alcohol, and 22.4 parts of water were stirred and mixed, and the natural dye was added. The water-based gravure ink (S2) used was obtained.

(Example 3) [Preparation of ink S3]
Super Monas P20000 (Benkoji dye (manufactured by Yaegaki Fermentation Giken Co., Ltd.)) 13.4 parts, PDX-7630a (manufactured by Johnson Polymer Co., Ltd.; styrene-acrylic copolymer aqueous dispersion having an acid value of 200 mgKOH/g, non-volatile matter 32%) ), 22.4 parts of isopropyl alcohol and 22.4 parts of water were stirred and mixed to obtain an aqueous gravure ink (S3) using a natural dye.

(Comparative Example 1) [Preparation of ink SS1]
10.0 parts of Super Monas P20000 (Benkoji pigment (manufactured by Yaegaki Fermentation Giken Co., Ltd.)),
Organic solvent-based polyurethane resin (PP1) 40.0 parts, vinyl chloride-vinyl acetate copolymer resin (Solbin TAO: manufactured by Nissin Chemical Co., Ltd., vinyl chloride/vinyl acetate/vinyl alcohol = 91/2/7 (mass ratio) 5 parts of polymer resin, 30% solid content ethyl acetate solution)), 37.0 parts of n-propyl acetate, 5 parts of IPA, and 3.0 parts of methyl propylene glycol were mixed, dispersed for 30 minutes with an Eiger mill, and a natural dye was used. An organic solvent-based gravure ink SS1 was obtained.

(Comparative Examples 2 and 3) [Preparation of Inks SS2 and SS3]
Water-based gravure ink SS2 and organic solvent-based gravure ink SS3 were obtained in the same manner as in Comparative Example 1 except that the raw materials and ratios shown in Table 1 were used. Abbreviations in the table indicate the following.
F-783: Organic pigment C.I. manufactured by Dainichi Seika Co., Ltd. I. pigment red 146

(Creation of printed matter) [Printing of ink S1]
The water-based gravure ink S1 obtained above was adjusted to 16 seconds with a Zahn cup #3 (manufactured by Rigosha) using a mixed solvent of water/isopropyl alcohol mixed solvent (mass ratio 1/1), Using a gravure printing machine equipped with a Helio 175 line gradation plate (plate type compressed gradation 100% to 3%), a cellophane film (PL made by Futamura Chemical Co., Ltd., thickness 20 μm, biomass content 90%) corona discharge treated on one side. A print was obtained using the aqueous gravure ink S1 on the treated surface at a printing speed of 80 m/min.

(Preparation of printed matter) [Printing of S2, S3 (Example) and SS1 to SS3 (Comparative Example)]
Inks S2 and S3 (Examples) and inks SS1 to SS3 (Comparative Examples) were used in the same manner as in Example 1 except that inks S2 and S3 (Examples) and inks SS1 to SS3 (Comparative Examples) were used. got the print. For dilution of the organic solvent-based gravure ink, a mixed solvent of MEK:n-propyl acetate:IPA=40:40:20 (mass ratio) was used to adjust the printing viscosity.

<Evaluation>
The gravure inks S1 to S3 (examples), SS1 to SS3 (comparative examples) and their printed matter were used for the following evaluations.

<Appearance>
Printed materials using S1 to S3 (Examples) and SS1 to SS3 (Comparative Examples) were cut into 200 mm×200 mm size test pieces, and the appearance was visually evaluated in the following five grades. In the following description, the term "unevenness" refers to a dark and light portion of a printed portion, and the term "defect" refers to pinholes, repellency, or the like in a printed portion.
(Evaluation criteria)
A. No visible unevenness or defects in printed matter (good)
B. You can visually confirm one unevenness or defect in the printed matter (practical use possible)
C. 2 or more and 5 or less of print irregularities or defects can be visually confirmed (slightly poor)
D. 6 or more and 10 or less irregularities or defects can be visually confirmed on the printed matter (defective)
E. 11 or more irregularities or defects can be visually confirmed on the printed matter (extremely poor)
It should be noted that A and B are within a practically acceptable range.

<Substrate transferability>
Regarding the prints using S1 to S3 (Examples) and SS1 to SS3 (Comparative Examples), substrate transferability evaluation was performed on the 5% gradation portion based on the percentage of the ink transfer area.
A. Ink transfer area is 100% (good)
B. Ink transfer area is 80% or more and less than 100% (practical)
C. Ink transfer area is 60% or more and less than 80% (slightly poor)
D. Ink transfer area is 30% or more and less than 60% (defective)
E. The ink transfer area is less than 30%. (extremely bad)
It should be noted that A and B are within a practically acceptable range.

<Plate fogging>
Gravure inks S1 to S3 (examples) and SS1 to SS3 (comparative examples) were evaluated for plate fogging. For the evaluation, the area of the plate fog portion was visually determined after 60 minutes of idling of the plate in the printing press.
A. Plate fogging area is less than 5% (good)
B. Plate fogging area is 5% or more and less than 10% (Practical)
C. Plate fogging area is 10% or more and less than 30% (slightly poor)
D. Plate fogging area is 30% or more and less than 50% (defective)
E. Covered area is 50% or more (extremely poor)
It should be noted that A and B are within a practically acceptable range.

According to the present invention, it was confirmed that biomass water-based dye-based printing inks using natural dyes are excellent in substrate transferability, plate clogging resistance, and plate fogging resistance to impermeable plastic film substrates. Furthermore, compared to conventional pigment-based gravure inks, the degree of biomass in the dry ink film is extremely high at 40% or more, and it is possible to achieve carbon neutrality through biomass conversion, which is expected for inks from the viewpoint of environmental conservation. did it.

Claims (5)

A water-based gravure ink containing a natural dye (A) and a water-based binder resin (B),
The ink has a biomass degree of 40% by mass or more in the total mass of non-volatile components,
The aqueous binder resin (B) contains an aqueous polyurethane resin (B1) and/or an aqueous vinyl resin (B2),
An aqueous gravure ink , wherein the aqueous polyurethane resin (B1) has an acid value of 10 to 60 mgKOH/g . 2. The water-based gravure ink according to claim 1 , wherein the water-based binder resin (B) water-based polyurethane resin (B1) has a structure derived from sebacic acid and/or succinic acid. The water-based gravure ink according to claim 1 or 2, wherein the natural dye (A) contains a dye derived from Benicouji. The gravure ink according to any one of claims 1 to 3, further comprising an ultraviolet absorber. A printed matter comprising a substrate and a printed layer comprising the water-based gravure ink according to any one of claims 1 to 4 .