JP2021080402A - Liquid printing ink, and laminate - Google Patents

Abstract

To provide liquid printing ink which has adhesion to a base material, brightness and concealing properties of a printed part by forming a laminate obtained by overprinting liquid printing ink and high brilliant ink.SOLUTION: A liquid printing ink contains a binder resin, and an organic solvent. The binder resin is a polyvinyl acetal resin.SELECTED DRAWING: None

Description

The present invention relates to a liquid printing ink that can be used for flexographic printing or gravure printing and is useful as an anchor varnish (primer) for printing reflective metal inks containing special pigments such as gold ink and silver ink.

Conventionally, special pigments such as gold ink, silver ink, and pearl ink have been applied to print designs and print patterns in order to give higher design to laminates for packaging materials such as various packages mainly made of paper base materials. Ingenuity has been made to improve the design by using the bright ink that contains it. Printed matter that imitates metallic luster is given a sense of design by using aluminum-bonded paper or metal-deposited paper as the base material, or by stamping metal leaf on the finished printed matter by post-processing. This is a general method.
However, these methods are costly, low in productivity, and uneconomical.
On the other hand, in order to express gold or silver color by ordinary flexographic printing or gravure printing, it is possible to use an ink containing aluminum paste or bronze powder, but the above-mentioned aluminum laminated paper or metal vapor deposition paper can be used. Compared to printed matter printed on a base material or stamped with metal foil in post-processing, the brightness and concealment of the printed part are inferior, so a sufficient metallic appearance cannot be obtained and high design can be obtained. It was never enough.

As an example of primer coating for paper and paperboard, a primer composition using an acrylic monomer having a specific functional group and an acrylic oligomer in a specific ratio is disclosed, but a UV irradiation device is indispensable, and hot air drying is the mainstream. The versatility of the gravure printing is low (for example, Patent Document 1: Japanese Patent Application Laid-Open No. 2019-94506).

JP-A-2019-94506

The problem to be solved by the present invention is to form a laminate in which the liquid printing ink of the present invention and the high-brightness ink are overprinted, thereby achieving adhesion to a base material, a feeling of brightness, and concealment of a printed portion. It is an object of the present invention to provide a liquid printing ink.

As a result of diligent research to solve the above problems, the present inventors have made a liquid printing ink containing a binder resin and an organic solvent, wherein the binder resin is a polyvinyl acetal resin. We have found that the above problems can be solved by using ink, and have completed the present invention.

That is, the present invention relates to a liquid printing ink containing a binder resin and an organic solvent, wherein the binder resin is a polyvinyl acetal resin.

Further, in the present invention, the polyvinyl acetal resin is a polyvinyl butyral resin, the glass transition temperature is 60 ° C. to 75 ° C., and the polyvinyl alcohol component in the resin is 10% by mass to 30% by mass in the total resin. Regarding a certain liquid printing ink.

The present invention also relates to a liquid printing ink further containing a rosin-based resin.

The present invention also relates to a liquid printing ink applied to flexographic printing or gravure printing.

Further, the present invention is a laminate having at least a first printing layer and a second printing layer on a paper base material in this order, and the first printing layer is a printing layer of a liquid printing ink. The present invention relates to a laminate characterized in that the second print layer is a print layer of a reflective metal ink.

The liquid printing ink of the present invention can have adhesion to a base material, a feeling of brightness, and concealment of a printed portion by forming a laminate in which a reflective metal ink is overprinted.

The liquid printing ink of the present invention is a liquid printing ink containing a binder resin and an organic solvent, and it is essential that the binder resin is a polyvinyl acetal resin.

Examples of the polyvinyl acetal resin include polyvinyl butyral resin and polyvinyl acetal resin.
The polyvinyl butyral resin may be a known one obtained by acetalizing polyvinyl alcohol with an aldehyde in the presence of an acid such as hydrochloric acid.
Of these, polyvinyl butyral resin is preferable, and it can be obtained by converting polyvinyl alcohol into butyral with butyl alcohol in the presence of an acid such as hydrochloric acid.
The polyvinyl alcohol resin is not particularly limited, and conventionally known polyvinyl alcohol resins such as those produced by saponifying polyvinyl acetate with alkali, acid, aqueous ammonia or the like can be used.
The polyvinyl alcohol resin may be completely saponified, but if there is at least one unit having two hydroxyl groups for the meso and racemic positions in at least one part of the main chain, it is completely saponified. It is not necessary to use a partially saponified polyvinyl alcohol resin.
Further, as the polyvinyl alcohol resin, a copolymer of vinyl alcohol and a monomer copolymerizable with vinyl alcohol, such as ethylene-vinyl alcohol copolymer resin and partially saponified ethylene-vinyl alcohol copolymer resin, is also used. be able to. Further, a modified polyvinyl alcohol resin in which a carboxylic acid or the like is partially introduced can also be used.
The method of acetalization is not particularly limited, and examples thereof include a method of adding an aldehyde and an acid catalyst to the aqueous solution of the polyvinyl alcohol resin and acetalizing by a known method. The aldehyde is not particularly limited, and for example, formaldehyde (including paraformaldehyde), acetaldehyde (including paraacetaldehyde), propionaldehyde, butylaldehyde, amylaldehyde, hexylaldehyde, heptylaldehyde, 2-ethylhexylaldehyde, cyclohexylaldehyde, etc. Examples thereof include furfural, glioxal, glutaaldehyde, benzaldehyde, 2-methylbenzaldehyde, 3-methylbenzaldehyde, 4-methylbenzaldehyde, p-hydroxybenzaldehyde, m-hydroxybenzaldehyde, phenylacetaldehyde, β-phenylpropionaldehyde and the like. These aldehydes may be used alone or in combination of two or more. Of these, butyraldehyde and / or acetaldehyde is preferably used.
The acid catalyst is not particularly limited, and examples thereof include organic acids such as acetic acid and p-toluenesulfonic acid, and inorganic acids such as nitric acid, sulfuric acid, and hydrochloric acid. The agent for stopping the acetalization reaction is not particularly limited, and for example, an alkali neutralizing agent such as sodium hydroxide, potassium hydroxide, ammonia, sodium acetate, sodium carbonate, sodium hydrogencarbonate, potassium carbonate, etc.; ethylene oxide and the like. Alkylene oxides; glycidyl ethers such as ethylene glycol diglycidyl ether can be mentioned.

The polyvinyl butyral resin used in the liquid printing ink of the present invention preferably has a glass transition temperature (hereinafter sometimes abbreviated as Tg) in the range of 60 ° C. to 75 ° C., and the glass transition temperature is within this range. For example, when a laminate obtained by overprinting a reflective metal ink is formed, it is possible to maintain a sense of brightness and a concealing property of a printed portion.
Further, it is preferable that the polyvinyl alcohol component in the polyvinyl butyral resin is 10% by mass to 30% by mass in the total resin.
When the polyvinyl alcohol component is 10% by mass or more in the total resin, the feeling of brightness tends to be maintained, and when it is 30% by mass or less, the adhesion tends to be maintained.
The binder resin is preferably in the range of 5 to 35% by mass of the total amount of the liquid printing ink in terms of solid content. If it is 5% by mass or more, the feeling of brightness tends to be maintained, and if it is 35% by mass or less, the adhesion tends to be maintained.

As the binder resin used in the liquid printing ink of the present invention, a ketone resin, an alkyd resin, nitrified cotton or the like may be used in combination.
Examples of the ketone resin include known and commonly used ones, and formaldehyde resin, cyclohexanone / formaldehyde resin, ketone aldehyde condensed resin and the like can be preferably used. Examples of the ketone resin include TEGOVariPlus AP, TEGOVariPlus SK, TEGOVariPlus 1201, and TEGOVariPlus CA manufactured by Evonik Japan.
The amount of the ketone resin added is preferably 0.5 to 30% by mass, more preferably 5 to 20% by mass, based on the total solid content of the binder resin.

The alkyd resin used in the present invention is obtained by condensing vegetable oils and their fatty acids, polyvalent carboxylic acids and polyhydric alcohols. The properties of alkyd resin are affected by the type of oil used for modification and its content, and considering the softening point and drying property of the resin, the oil length indicating the ratio of the oil and fat used to the resin content is 50 to 50 to 90% is preferable. If the oil length is longer than 50%, the stability on the printing press is maintained without drying too fast. Further, if the oil length is shorter than 90%, the property as a vegetable oil is unlikely to be strengthened, and the pigment dispersion effect tends to be maintained.
The amount of the alkyd resin added is preferably 0.5 to 30% by mass, more preferably 5 to 20% by mass, based on the total solid content of the binder resin.

The nitricized cotton used in the present invention can be obtained as a nitrate ester in which three hydroxyl groups in the 6-membered ring of the anhydrous glucopyranose group in the natural cellulose are replaced with a nitric acid group by reacting natural cellulose with nitric acid. Is preferable.
By using nitricized cotton, high dispersibility in pigments can be obtained, so that the strength of the printing ink coating film can be improved, which is preferable. The nitricized cotton preferably has a nitrogen content of 10 to 13% by mass and an average degree of polymerization of 30 to 500, and more preferably a nitrogen content of 10 to 13% by mass and an average degree of polymerization of 45 to 290.
The amount of nitrified cotton added is preferably 0.5 to 30% by mass, more preferably 5 to 20% by mass, based on the total amount of the binder resin solid content.

It is more preferable that the liquid printing ink of the present invention contains a rosin-based resin as a binder resin for the purpose of improving the adhesion to the substrate. Examples of the rosin-based resin include rosin, hydrogenated rosin, acid-modified rosin, and ester rosin.
Examples of the rosin include unmodified rosins such as tall oil rosin, gum rosin, and wood rosin containing a resinic acid as a main component such as abietic acid, levopimalic acid, pulsetriic acid, neoavietic acid, dehydroabietic acid, and dihydroabietic acid.
Hydrogenated unmodified rosins can be used as hydrogenated rosins.
Examples of the acid-modified rosin include fumaropimalic acid in which fumaric acid is added to rosin by the Deals-Alder addition reaction, maleopimalic acid in which maleic acid is added, and the like.
Among the acid-modified rosins, rosin maleate is particularly preferable.
Examples of the esterified rosin include a glycerin ester obtained by esterifying rosin and glycerin, and a pentaerythritol ester obtained by esterifying pentaerythritol.

The rosin-based resin preferably has an acid value of 150 to 250 mgKOH / g. If the acid value of the rosin resin is 150 mgKOH / g or more, the tendency of the reprintability to decrease can be suppressed, and if it is 250 mgKOH / g or less, the solubility in the solvent does not decrease and the storage stability of the ink is maintained. It tends to be easy. The softening point of the rosin-based resin is preferably 100 to 170 ° C. When the softening point of the rosin resin is 100 ° C. or higher, the tendency of the ink coating film to become soft and the blocking property is lowered can be suppressed, and when the softening point is 170 ° C. or lower, the solubility in an organic solvent tends to be lowered. This can be avoided and the storage stability of the ink tends to be maintained.
The amount of the rosin-based resin added is preferably 0.5 to 30% by mass, more preferably 3 to 25% by mass, and may be in the range of 5 to 20% by mass with respect to the total solid content of the binder resin. Is even more preferable.

The organic solvent used in the liquid printing ink of the present invention is not particularly limited, but is, for example, aromatic hydrocarbons such as toluene, xylene, sorbesso # 100 and sorbesso # 150, hexane, methylcyclohexane, heptane, octane and decane. Examples thereof include various organic solvents such as aliphatic hydrocarbons such as methyl acetate, ethyl acetate, isopropyl acetate, normal propyl acetate, butyl acetate, amyl acetate, ethyl formate and butyl propionate. Also, as water-mixable organic solvents, alcohol-based solvents such as methanol, ethanol, propanol, butanol, and isopropyl alcohol, ketone-based solvents such as acetone, methyl ethyl ketone, and cyclohaxanone, ethylene glycol (mono, di) methyl ether, and ethylene glycol (mono, di) ethyl. Ether, ethylene glycol monopropyl ether, ethylene glycol monoisopropyl ether, monobutyl ether, diethylene glycol (mono, di) methyl ether, diethylene glycol (mono, di) ethyl ether, diethylene glycol monoisopropyl ether, diethylene glycol monobutyl ether, triethylene glycol (mono, di) Examples thereof include various glycol ether-based organic solvents such as di) methyl ether, propylene glycol (mono, di) methyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, and dipropylene glycol (mono, di) methyl ether. These can be used alone or in combination of two or more.
It is more preferable not to use an aromatic hydrocarbon solvent such as toluene or xylene from the viewpoints of both work hygiene during printing and harmfulness of the packaging material.

Since the liquid printing ink of the present invention of the present invention is mainly useful as an anchor varnish (primer) for printing reflective metal inks containing special pigments such as gold ink and silver ink, it is not possible to use a colorant together in principle. Although it is small, organic pigments and / or inorganic pigments used in general inks, paints, recording agents, etc. may be added as needed, as long as the feeling of brightness and the concealing property of the printed portion are not significantly deteriorated.

Examples of the coloring pigment used in the liquid printing ink of the present invention include organic pigments and dyes. Organic pigments include azo-based, phthalocyanine-based, anthraquinone-based, perylene-based, perinone-based, quinacridone-based, thioindigo-based, dioxazine-based, isoindolinone-based, quinophthalone-based, azomethinazo-based, dictopyrrolopyrrole-based, and isoindoline-based. Pigments can be mentioned.

As a typical color index name,
C. I. Pigment Yellow 1, 3, 12, 13, 14, 17, 42, 74, 83;
C. I. Pigment Orange 16;
C. I. Pigment Red 5, 22, 38, 48: 1, 48: 2, 48: 4, 49: 1, 53: 1, 57: 1, 63: 1, 81, 101;
C. I. Pigment Violet 19, 23;
C. I. Pigment Blue 23, 15: 1, 15: 3, 15: 4, 17: 1, 18, 27, 29
C. I. Pigment Green 7, 36, 58, 59;
C. I. Pigment Black 7;
C. I. Pigment White 4, 6, 18 and the like.

For indigo ink, C.I. I. Pigment Blue 15: 3 (copper phthalocyanine), yellow ink is C.I. from the viewpoint of cost and light resistance. I. Pigment Yellow83, C.I. for red ink. I. Pigment Red 57: 1, preferably carbon black is used as the black ink.

Examples of the inorganic pigment include white inorganic pigments such as titanium oxide, zinc oxide, zinc sulfide, barium sulfate, calcium carbonate, chromium oxide, silica, lithobon, antimony white, and gypsum. Among the inorganic pigments, the use of titanium oxide is particularly preferable. Titanium oxide has a white color and is preferable from the viewpoints of coloring power, hiding power, chemical resistance and weather resistance, and from the viewpoint of printing performance, the titanium oxide is preferably treated with silica and / or alumina.

The gold and silver inks of the reflective metal ink are preferably mixed with a vapor-deposited aluminum pigment and, if necessary, the coloring pigment. A vapor-deposited aluminum pigment (aluminum pigment produced by a vapor deposition method) is an aluminum flake produced by a vapor deposition method. In the above-mentioned thin-film deposition method, a metal (aluminum in the present invention) is vapor-deposited on an appropriate supporting base material (film, etc.) to prepare a thin-film metal (aluminum) film, which is then peeled off, pulverized, and if necessary. This is a method for producing thin-film vapor-deposited metal film fragments (deposited aluminum flakes) that are classified into flakes. According to the above-mentioned thin-film deposition method, aluminum flakes that are plate-shaped and thinner in thickness can be obtained as compared with the case of manufacturing by pulverization with a conventional ball mill (sometimes referred to as "ball mill method" or "wet ball mill method"). Can be done. Therefore, in the printing layer, the aluminum flakes, which are pigments, are likely to be oriented in the direction parallel to the paper base material, the orientation is improved, and the incident light is easily reflected. Therefore, the mirror glossiness and the transmission density of the print layer are improved, and an excellent metallic luster is exhibited.

The average particle size of the vapor-deposited aluminum pigment is preferably in the range of 5 to 40 μm, more preferably 8 to 20 μm. The pigment is in an amount sufficient to secure the concentration and coloring power of the oil-based liquid printing ink, that is, 1 to 60% by mass with respect to the total mass of the ink, and 5 to 90% by mass in terms of the solid content mass ratio in the ink. It is preferably contained in proportion. In addition, these pigments can be used alone or in combination of two or more.

In addition, in the present invention, extender pigments, pigment dispersants, leveling agents, defoaming agents, plasticizers, infrared absorbers, ultraviolet absorbers, fragrances, flame retardants and the like can also be included. Among them, polyolefins such as high-density polymerized polyethylene, low-density polymerized polyethylene, and oxidized polyethylene for imparting abrasion resistance and slipperiness, and silicon-based and non-silicon-based defoamers for suppressing foaming during printing. Various dispersants and the like that improve the wetting of agents and pigments are useful.

(Manufacturing method of liquid printing ink)
The liquid printing ink of the present invention is obtained by dispersing a mixture of a binder resin, an organic solvent, and other additives with a disperser and stirring and mixing them. As the disperser, it is manufactured by using a bead mill, an Eiger mill, a sand mill, a gamma mill, an attritor or the like which are generally used for manufacturing gravure and flexographic printing inks.

(Creation of printed matter)
The liquid printing ink of the present invention has excellent adhesion to various base materials and can be used for printing on paper, synthetic paper, thermoplastic resin film, plastic products, steel plates, etc. It is useful as an ink for gravure printing using a gravure printing plate, or for flexographic printing using a flexographic printing plate such as a resin plate, but for an inkjet method in which ink is ejected from an inkjet nozzle without using a plate. It excludes ink. That is, in the case of inkjet ink, the ink droplets ejected from the nozzle directly adhere to the substrate to form a printed matter, whereas in the water-based liquid ink of the present invention, the printing ink is once adhered to and transferred to the printing plate or printing pattern. After that, only the ink is brought into close contact with the base material again, and if necessary, it is dried to obtain a printed matter.
The film thickness of the printing ink formed by the gravure printing method or the flexographic printing method using the liquid printing ink of the present invention is, for example, 10 μm or less, preferably 5 μm or less.

When the liquid printing ink of the present invention is used, for example, it is a laminate having at least a first printing layer and a second printing layer on a paper substrate in this order, and the first printing layer is the liquid printing ink. The second printing layer can form a laminate composed of a printing layer of a reflective metal ink such as silver ink. Further, if necessary, an overprint varnish may be provided on the second print layer.
Specifically, for example, using a gravure printing machine equipped with a plate depth of 175 L / inch gravure plate on coated paper as printing paper, the liquid printing ink of the present invention and silver ink as high-brightness ink are printed in this order. A laminate can be obtained. Further, an oil-based or water-based overprint varnish may be printed on the laminate.

Reflective metal inks applied to porous and non-smooth substrates such as paper substrates permeate and soak into the porous substrate and dry in the non-smooth layer following the non-smooth surface contour of the substrate, resulting in As a result, it provides a low-brightness print appearance with low reflectivity. It is recommended to use the liquid ink of the present invention as a primer to prevent the penetration of the high-luminance ink and to control the orientation of the vapor-deposited aluminum pigment to help improve the brightness.

The printing base material for printing the liquid printing ink of the present invention is mainly high-quality paper, coated paper, art paper, etc. used for package printing of, for example, tobacco packaging, confectionery, cosmetics and beverages, pharmaceuticals, toys, electronic parts, etc. Paper base materials such as imitation paper, thin paper, thick paper, and various synthetic papers are preferable, but polyester resin, acrylic resin, vinyl chloride resin, vinylidene chloride resin, polyvinyl alcohol, polyethylene, polypropylene, polyacrylonitrile, and vinyl ethylene acetate are all used. Laminated using a polymer, ethylene vinyl alcohol copolymer, ethylene methacrylate copolymer, film or sheet such as nylon, polylactic acid, polycarbonate, cellophane, aluminum foil, or other substrate conventionally used as a printing substrate. You can make a body.

Hereinafter, the present invention will be described in more detail with reference to Examples. In the examples, "parts" represents "parts by mass" and "%" represents "% by mass".
The weight average molecular weight (in terms of polystyrene) measured by GPC (gel permeation chromatography) in the present invention was measured using the HLC8220 system manufactured by Tosoh Corporation under the following conditions.
Separation column: Uses 4 TSKgelGMHR-N manufactured by Tosoh Corporation. Column temperature: 40 ° C. Moving layer: Tetrahydrofuran manufactured by Wako Pure Chemical Industries, Ltd. Flow velocity: 1.0 ml / min. Sample concentration: 1.0% by mass. Sample injection volume: 100 microliters. Detector: Differential refractometer.
The glass transition temperature (Tg) is measured by using a differential scanning calorimeter (“DSC Q100” manufactured by TA Instruments Co., Ltd.) in a nitrogen atmosphere and using a cooling device to raise the temperature in the temperature range of -80 to 450 ° C. This was performed by scanning under the condition of a temperature of 10 ° C./min.

[Adjustment example 1]
A liquid printing ink was prepared by mixing and stirring 20 parts of polyvinyl butyral resin A (Tg 63 ° C., 19.5% polyvinyl alcohol component), 40 parts of isopropyl alcohol, and 40 parts of methyl ethyl ketone. Using the obtained liquid printing ink as a viscosity adjusting solvent, a diluting solvent was used, and Zahn Cup No. The viscosity was adjusted to 18 seconds (25 ° C.) at 3. Isopropyl alcohol: methyl ethyl ketone = 50:50 (mass ratio) was used as the diluting solvent.

[Adjustment example 2]
Except that 20 parts of polyvinyl butyral resin B (Tg 70 ° C., polyvinyl alcohol component 25.5%) was used instead of 20 parts of polyvinyl butyral resin A (Tg 63 ° C., polyvinyl alcohol component 19.5%) in Adjustment Example 1. A liquid printing ink was prepared by the same formulation and procedure as in Adjustment Example 1.

[Adjustment example 3]
Except that 20 parts of polyvinyl butyral resin C (Tg 70 ° C., polyvinyl alcohol component 25.5%) was used instead of 20 parts of polyvinyl butyral resin A (Tg 63 ° C., polyvinyl alcohol component 19.5%) in Adjustment Example 1. A liquid printing ink was prepared by the same formulation and procedure as in Adjustment Example 1.

[Adjustment example 4]
Except that 20 parts of polyvinyl butyral resin D (Tg 72 ° C., polyvinyl alcohol component 25.5%) was used instead of 20 parts of polyvinyl butyral resin A (Tg 63 ° C., polyvinyl alcohol component 19.5%) in Adjustment Example 1. A liquid printing ink was prepared by the same formulation and procedure as in Adjustment Example 1.

[Adjustment example 5]
20 parts of polyvinyl butyral resin A (Tg 63 ° C., polyvinyl alcohol component 19.5%), marquid NO. A liquid printing ink was prepared by mixing and stirring 4 parts of 31 (manufactured by Arakawa Chemical Industry Co., Ltd.), 36 parts of isopropyl alcohol, and 40 parts of methyl ethyl ketone. Using the obtained liquid printing ink as a viscosity adjusting solvent, a diluting solvent was used, and Zahn Cup No. The viscosity was adjusted to 18 seconds (25 ° C.) at 3. Isopropyl alcohol: methyl ethyl ketone = 50:50 (mass ratio) was used as the diluting solvent.

[Adjustment example 6]
A primer is prepared by mixing and stirring 20 parts of polyvinyl butyral resin A (Tg 63 ° C., polyvinyl alcohol component 19.5%), 4 parts of TEGOVARIPLUS CA (manufactured by Ebonic Japan Co., Ltd.), 36 parts of isopropyl alcohol, and 40 parts of methyl ethyl ketone as a ketone resin. did. Using the obtained liquid printing ink as a viscosity adjusting solvent, a diluting solvent was used, and Zahn Cup No. The viscosity was adjusted to 18 seconds (25 ° C.) at 3. Isopropyl alcohol: methyl ethyl ketone = 50:50 (mass ratio) was used as the diluting solvent.

[Adjustment example 7]
A primer was prepared by mixing and stirring 20 parts of polyvinyl butyral resin A (Tg 63 ° C., polyvinyl alcohol component 19.5%), 4 parts of alkyd resin 1308E (manufactured by DIC Corporation), 36 parts of isopropyl alcohol, and 40 parts of methyl ethyl ketone. .. Using the obtained liquid printing ink as a viscosity adjusting solvent, a diluting solvent was used, and Zahn Cup No. The viscosity was adjusted to 18 seconds (25 ° C.) at 3. Isopropyl alcohol: methyl ethyl ketone = 50:50 (mass ratio) was used as the diluting solvent.

[Adjustment example 8]
Viscosity at a solution concentration of 25.0% according to 20 parts of polyvinyl butyral resin A (Tg 63 ° C., polyvinyl alcohol component 19.5%), industrial vitrified cotton L1 / 8 (nitrocellulose, solid content 70%, JIS K-6703). 6-2.9% product Taihei Chemicals Limited) 4 parts, 36 parts of isopropyl alcohol and 40 parts of methyl ethyl ketone were mixed and stirred to prepare a primer. Using the obtained liquid printing ink as a viscosity adjusting solvent, a diluting solvent was used, and Zahn Cup No. The viscosity was adjusted to 18 seconds (25 ° C.) at 3. Isopropyl alcohol: methyl ethyl ketone = 50:50 (mass ratio) was used as the diluting solvent.

[Adjustment example 9]
30 parts of industrial nitrified cotton L1 / 8 (nitrocellulose, solid content 70%, viscosity 1.6-2.9% at a solution concentration of 25.0% according to JIS K-6703, manufactured by Taihei Chemicals Limited), isopropyl alcohol A nitrocellulose solution was prepared by mixing and stirring 20 parts and 50 parts of ethyl acetate. Using the obtained nitrocellulose solution as a viscosity adjusting solvent, a diluting solvent was used, and Zahn Cup No. The viscosity was adjusted to 18 seconds (25 ° C.) at 3. Isopropyl alcohol: ethyl acetate = 30:70 (mass ratio) was used as the diluting solvent.

[Adjustment example 10]
An acrylic resin solution was prepared by mixing and stirring 20 parts of Paraloid A11 (acrylic resin, Tg: 100 ° C., manufactured by Rome And Haas Company), 40 parts of methyl ethyl ketone, and 40 parts of toluene. Using the obtained acrylic resin solution as a viscosity adjusting solvent, a diluting solvent was used, and Zahn Cup No. The viscosity was adjusted to 18 seconds (25 ° C.) at 3. Methyl ethyl ketone: toluene = 50:50 (mass ratio) was used as the diluting solvent.

[Adjustment example 11]
A vinyl chloride resin solution was prepared by mixing and stirring 20 parts of solveine A (vinyl chloride vinyl acetate resin, Tg: 76 ° C., manufactured by Nisshin Chemical Industry Co., Ltd.), 50 parts of methyl ethyl ketone, and 30 parts of normal propyl acetate. Using the obtained vinyl chloride vinyl acetate resin solution as a viscosity adjusting solvent, a diluting solvent was used, and Zahn Cup No. The viscosity was adjusted to 18 seconds (25 ° C.) at 3. As a diluting solvent, methyl ethyl ketone: normal propyl acetate = 75:25 (mass ratio) was used.

[Making silver ink]
Industrial vitrified cotton L1 / 8 (nitrocellulose, solid content 70%, viscosity 1.6-2.9% at a solution concentration of 25.0% according to JIS K-6703, manufactured by Taihei Chemicals Limited), isopropyl alcohol After mixing and stirring 6 parts and 48 parts of ethyl acetate to prepare a nitrocellulose solution, 40 parts of vapor-deposited aluminum pigment BASF, "Metasheen 11-0010", average particle size: 10 μm, non-volatile content: 10% by mass) are mixed. A silver ink for overprinting was prepared by stirring. Using the obtained silver ink as a viscosity adjusting solvent, a diluting solvent was used, and Zahn Cup No. The viscosity was adjusted to 18 seconds (25 ° C.) at 3. Ethyl acetate: normal propyl acetate = 50:50 (weight ratio) was used as the diluting solvent.

[Example 1]
Printing on coated paper (CRC 230 g, manufactured by Rengo Co., Ltd.) as printing paper in the order of liquid printing ink and silver ink obtained in Adjustment Example 1 using a gravure proofing machine equipped with a plate depth of 175 L / inch gravure plate. A printed matter (laminated body) was obtained.

[Examples 2 to 8]
Instead of the liquid printing ink obtained in Adjustment Example 1 of Example 1, the printed matter obtained by printing the liquid printing ink obtained in Adjustment Examples 2 to 8 and the silver ink in this order was designated as Examples 2 to 8, respectively. ..

[Comparative Example 1]
Comparative Example 1 was obtained by printing silver ink directly on the printing paper using a gravure proofing machine equipped with a plate depth of 175 L / inch gravure plate on coated paper (CRC 230 g, manufactured by Rengo Co., Ltd.) as the printing paper.

[Comparative Examples 2 to 4]
Instead of the liquid printing ink obtained in Adjustment Example 1 of Example 1, the printed matter obtained in the order of the liquid printing ink obtained in Adjustment Examples 9 to 11 and the silver ink was designated as Comparative Examples 2 to 4, respectively. ..

The glossiness, concealment property, and substrate adhesion of each printed matter produced were evaluated according to the following evaluation procedure.

[Evaluation item 1: Gloss]
The metallic appearance of the printed matter was measured at 20 ° and 60 ° using a mirror gloss meter (“micro-TRI-gloss” manufactured by BYK-Gardner) in accordance with JIS Z 8741. The larger the numerical value, the higher the glossiness, indicating that the brilliance is excellent.

[Evaluation item 2: Concealment]
The metallic appearance of the printed matter was visually evaluated. The evaluation criteria are as follows.

(Evaluation criteria)
◯: The transferability of silver ink is good, and almost no plain part of the base paper is seen. Δ: The transferability of silver ink is slightly inferior, and a plain part of less than 20% is seen.
Within the practical range ×: The transferability of silver ink is inferior, and a plain part of 20% or more is observed.

[Evaluation item 3: Adhesion to base material]
After each of the produced printed matter was left for one day, a cellophane tape (Nichiban 12 mm width) was attached to the printed surface, and the appearance of the printed film when the printed matter was rapidly peeled off was visually evaluated.

(Evaluation criteria)
◯: 50% or more of the silver ink film is peeled off from the paper coat layer, and paper fibers are visible.
Δ: Less than 50% of the silver ink film is peeled off from the paper coat layer, and paper fibers are visible, but this is within the practical range.
X: The silver ink film is peeled off, but the paper fibers are not visible because it is not peeled off from the coat layer.

Table 1 shows the formulation of each adjustment example of the liquid printing ink, and Table 2 shows the evaluation results of each of the produced printed matter.

The liquid printing ink of the present invention can have adhesion to a base material, a feeling of brightness due to high glossiness, and sufficient concealment of a printed portion in a printed matter overprinted with silver ink.

Claims (5)

A liquid printing ink containing a binder resin and an organic solvent, wherein the binder resin is a polyvinyl acetal resin.
The first aspect of claim 1, wherein the polyvinyl acetal resin is a polyvinyl butyral resin, the glass transition temperature is 60 ° C. to 75 ° C., and the polyvinyl alcohol component in the resin is 10% by mass to 30% by mass in the total resin. Liquid printing ink.
The liquid printing ink according to claim 1 or 2, further containing a rosin-based resin.
The liquid printing ink according to any one of claims 1 to 3, which is applied to flexographic printing or gravure printing.
A laminate having at least a first printing layer and a second printing layer on a paper substrate in this order.
The first printing layer is the printing layer of the liquid printing ink according to any one of claims 1 to 4, and the second printing layer is the printing layer of the reflective metal ink. Laminated body.