JP7392195B1 - Liquid printing ink and laminates - Google Patents

Abstract

[Problem] 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 a high brightness ink are overprinted to improve adhesion to the base material, brightness, and concealment of the printed part. The purpose of the present invention is to provide a liquid printing ink that has both properties. [Solution] As a result of intensive research in order to solve the above problems, the present inventors have found that the solution of the present invention is a liquid printing ink containing a binder resin and an organic solvent, wherein the binder resin is polyvinyl acetal resin. This invention relates to a liquid printing ink characterized by: [Selection diagram] None

Description

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

Traditionally, special pigments such as gold ink, silver ink, pearl ink, etc. have been applied to printing designs and patterns in order to give higher design quality to laminates for packaging materials such as various packages mainly made of paper base material. Efforts have been made to improve the design quality by using glittering ink containing. Prints that imitate metallic luster are given a sense of design by using aluminum laminated paper or metallized paper as the base material, or by stamping metal foil on the finished prints in post-processing. This is a common method.
However, these methods are expensive, have low productivity, and are not economical.
On the other hand, it is also possible to use ink containing aluminum paste or bronze powder to express gold or silver colors with regular flexographic printing or gravure printing, but it is also possible to use ink containing aluminum paste or bronze powder, but it is also possible to use ink containing aluminum paste or bronze powder. Compared to printed matter printed on a base material or stamped with metal foil in post-processing, this method does not provide a sufficient metallic appearance due to inferior brightness and concealment of the printed area, but is a method that provides a high level of design. It was never enough.

As an example of primer coating for paper and paperboard, a primer composition using acrylic monomers and acrylic oligomers with specific functional groups in a specific ratio has been disclosed, but a UV irradiation device is essential and hot air drying is mainstream. Gravure printing has low versatility (for example, Patent Document 1: JP 2019-94506).

JP2019-94506A

The problem to be solved by the present invention is to form a laminate by overprinting the liquid printing ink of the present invention and a high brightness ink, thereby achieving both adhesion to the base material, brightness, and concealment of the printed area. The purpose is to provide a liquid printing ink that

As a result of intensive research to solve the above problems, the present inventors have discovered a liquid printing ink containing a binder resin and an organic solvent, wherein the binder resin is a polyvinyl acetal resin. The inventors have discovered 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% to 30% by mass based on the total resin. Regarding a certain liquid printing ink.

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

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

Further, the present invention provides a laminate having at least a first printed layer and a second printed layer in this order on a paper base material, the first printed layer being a printed layer of liquid printing ink, The present invention relates to a laminate, wherein the second printed layer is a printed layer of reflective metallic ink.

The liquid printing ink of the present invention can have adhesion to the base material, brightness, and concealment of the printed part by forming a laminate in which 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 the binder resin is essentially a polyvinyl acetal resin.

Examples of the polyvinyl acetal resin include polyvinyl butyral resin, polyvinyl acetoacetal resin, and the like.
The polyvinyl butyral resin may be a known resin obtained by acetalizing polyvinyl alcohol with an aldehyde in the presence of an acid such as hydrochloric acid.
Among these, polyvinyl butyral resin is preferred, and can be obtained by butyralizing polyvinyl alcohol 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, etc. can be used.
The above-mentioned polyvinyl alcohol resin may be completely saponified, but it is completely saponified if it has at least one unit having a double hydroxyl group in the meso or racemic position at least at one location in the main chain. It is not necessary to use a partially saponified polyvinyl alcohol resin.
Furthermore, as the polyvinyl alcohol resin, a copolymer of vinyl alcohol and a monomer copolymerizable with vinyl alcohol, such as an ethylene-vinyl alcohol copolymer resin or a partially saponified ethylene-vinyl alcohol copolymer resin, may also be used. be able to. Furthermore, a modified polyvinyl alcohol resin into which a carboxylic acid or the like is introduced can also be used.
The method of acetalization is not particularly limited, and includes, for example, a method of adding an aldehyde and an acid catalyst to an aqueous solution of the polyvinyl alcohol resin and performing acetalization using a known method. The above aldehydes are not particularly limited, and include, for example, formaldehyde (including paraformaldehyde), acetaldehyde (including paraacetaldehyde), propionaldehyde, butyraldehyde, amylaldehyde, hexylaldehyde, heptylaldehyde, 2-ethylhexylaldehyde, cyclohexylaldehyde, Examples include furfural, glyoxal, glutaraldehyde, 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. Among these, it is preferable to use butyraldehyde and/or acetaldehyde.
The acid catalyst is not particularly limited, and includes, for example, organic acids such as acetic acid and p-toluenesulfonic acid, and inorganic acids such as nitric acid, sulfuric acid, and hydrochloric acid. In addition, the terminator for the acetalization reaction is not particularly limited, and includes, for example, alkali neutralizing agents such as sodium hydroxide, potassium hydroxide, ammonia, sodium acetate, sodium carbonate, sodium bicarbonate, and potassium carbonate; ethylene oxide, etc. Alkylene oxides include glycidyl ethers such as ethylene glycol diglycidyl ether.

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 even if the glass transition temperature is within this range. For example, when a laminate is formed by overprinting reflective metal ink, it is possible to maintain the brightness and concealability of the printed portion.
Further, it is preferable that the polyvinyl alcohol component in the polyvinyl butyral resin is 10% by mass to 30% by mass based on the total resin.
If the polyvinyl alcohol component is 10% by mass or more based on the total resin, brightness tends to be maintained, and if it is 30% by mass or less, adhesiveness tends to be maintained.
Incidentally, the binder resin preferably ranges from 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, brightness tends to be maintained, and if it is 35% by mass or less, adhesion tends to be maintained.

As the binder resin used in the liquid printing ink of the present invention, ketone resin, alkyd resin, nitrified cotton, etc. may be used in combination.
Examples of the ketone resin include known and commonly used ones, and formaldehyde resins, cyclohexanone formaldehyde resins, ketone aldehyde condensation resins, and the like can be suitably used. Examples of the ketone resin include TEGOVariPlus AP, TEGOVariPlus SK, TEGOVariPlus 1201, and TEGOVariPlus CA manufactured by Evonik Japan.
The amount of 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, their fatty acids, polyhydric carboxylic acids, and polyhydric alcohols. The properties of alkyd resin are affected by the type and content of oil used for modification, and if the softening point and drying properties of the resin are taken into consideration, the oil length, which indicates the ratio of oil to resin content, can be calculated from 50 to 50. 90% is preferred. If the oil length is longer than 50%, stability on the printing press can be maintained without drying too quickly. Moreover, if the oil length is shorter than 90%, the properties as a vegetable oil will not become strong, and the pigment dispersion effect will tend to be maintained.
The amount of 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 nitrified cotton used in the present invention is obtained as a nitric acid ester in which three hydroxyl groups in the six-membered ring of the anhydrous glucopyranose group in natural cellulose are replaced with nitric acid groups by reacting natural cellulose with nitric acid. Preferably.
By using nitrified cotton, high dispersibility in the pigment can be obtained, and therefore the strength of the printing ink coating can be improved, which is preferable. The nitrified cotton preferably has a nitrogen content of 10 to 13% by mass and an average degree of polymerization of 30 to 500, 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 solid content of the binder resin.

It is more preferable that the liquid printing ink of the present invention contains a rosin resin as a binder resin for the purpose of improving adhesion to the substrate. Examples of the rosin resin include rosin, hydrogenated rosin, acid-modified rosin, and ester rosin.
Examples of the rosin include unmodified rosin, such as tall oil rosin, gum rosin, and wood rosin, which are mainly composed of resin acids such as abietic acid, levopimaric acid, palustric acid, neoabietic acid, dehydroabietic acid, or dihydroabietic acid.
Each of the unmodified rosins described above can be hydrogenated and used as the hydrogenated rosin.
Examples of the acid-modified rosin include fumaropimaric acid obtained by adding fumaric acid to rosin by Diels-Alder addition reaction, maleopimaric acid obtained by adding maleic acid, and the like.
Among the aforementioned acidic modified rosins, maleic acid rosin is particularly preferred.
Examples of the esterified rosin include glycerin ester obtained by esterifying rosin and glycerin, and pentaerythritol ester obtained by esterifying pentaerythritol.

The rosin 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 for overprinting suitability to decrease can be suppressed, and if it is 250 mgKOH/g or less, the solubility in solvents will not decrease and the storage stability of the ink will be maintained. It tends to be easy. Further, the softening point of the rosin resin is preferably 100 to 170°C. If the softening point of the rosin resin is 100°C or higher, the tendency for the ink coating to become soft and the blocking property to decrease can be suppressed, and if the softening point is 170°C or lower, the tendency for the solubility in organic solvents to decrease can be suppressed. This can be avoided and the storage stability of the ink tends to be maintained.
The amount of rosin resin added is preferably 0.5 to 30% by mass, more preferably 3 to 25% by mass, and even within the range of 5 to 20% by mass based on the total solid content of the binder resin. It is even more preferable.

The organic solvent used in the liquid printing ink of the present invention is not particularly limited, but includes aromatic hydrocarbons such as toluene, xylene, Solvesso #100 and Solvesso #150, hexane, methylcyclohexane, heptane, octane, and decane. and ester-based organic solvents such as methyl acetate, ethyl acetate, isopropyl acetate, n-propyl acetate, butyl acetate, amyl acetate, ethyl formate, and butyl propionate. In addition, water-miscible organic solvents include alcohols such as methanol, ethanol, propanol, butanol, and isopropyl alcohol, ketones 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 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.
In addition, from the viewpoint of both operational hygiene during printing and toxicity of packaging materials, it is more preferable not to use aromatic hydrocarbon solvents such as toluene and xylene.

The liquid printing ink of the present invention is mainly useful as an anchor varnish (primer) for printing with reflective metal inks containing special pigments such as gold ink and silver ink, so in principle, colorants should not be used together. Although the amount is small, organic pigments and/or inorganic pigments used in general inks, paints, recording agents, etc. may be added as necessary to the extent that the brightness and hiding properties of printed areas are not significantly reduced.

The colored pigments used in the liquid printing ink of the present invention include organic pigments and dyes. Examples of organic pigments include azo, phthalocyanine, anthraquinone, perylene, perinone, quinacridone, thioindigo, dioxazine, isoindolinone, quinophthalone, azomethine azo, dictopyrrolopyrrole, and isoindoline. Examples include pigments.

Typical color index names include:
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.

C. for indigo ink. I. Pigment Blue 15:3 (copper phthalocyanine), yellow ink is C. I. Pigment Yellow 83, C. I. Pigment Red 57:1 and carbon black are preferably used for 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, use of titanium oxide is particularly preferred. Titanium oxide is white and is preferred from the viewpoint of coloring power, hiding power, chemical resistance, and weather resistance. From the viewpoint of printing performance, the titanium oxide is preferably treated with silica and/or alumina.

It is preferable that the gold or silver ink of the reflective metal ink contains a vapor-deposited aluminum pigment and, if necessary, the coloring pigment. Vapor-deposited aluminum pigments (aluminum pigments produced by vapor deposition) are aluminum flakes produced by vapor deposition. The above-mentioned vapor deposition method is to create a vapor-deposited metal (aluminum) film by vapor-depositing a metal (aluminum in the present invention) on a suitable supporting substrate (film, etc.), then peeling it off, pulverizing it, and, if necessary, This is a method for producing vapor-deposited metal film strips (vapor-deposited aluminum flakes) that are classified into flakes. According to the above vapor deposition method, it is possible to obtain aluminum flakes that are plate-shaped and thinner than those produced by conventional pulverization using a ball mill (sometimes referred to as the "ball mill method" or "wet ball mill method"). I can do it. Therefore, in the printing layer, the aluminum flakes that are pigments are easily oriented in a direction parallel to the paper base material, and the orientation is improved, making it easier to regularly reflect incident light. Therefore, the specular gloss and transmission density of the printed layer are improved, and 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 used in an amount sufficient to ensure the concentration and coloring power of the oil-based liquid printing ink, that is, 1 to 60% by mass based on the total mass of the ink, and 5 to 90% by mass in terms of solid content in the ink. It is preferable that it is contained in a proportion. Further, these pigments can be used alone or in combination of two or more.

In the present invention, extender pigments, pigment dispersants, leveling agents, antifoaming agents, plasticizers, infrared absorbers, ultraviolet absorbers, fragrances, flame retardants, and the like may also be included. Among them, polyolefins such as high-density polymerized polyethylene, low-density polymerized polyethylene, and oxidized polyethylene to provide friction resistance and slipperiness, and silicone-based and non-silicon-based antifoaming to suppress foaming during printing. Various dispersants and the like that improve wetting of agents and pigments are useful.

(Method for manufacturing liquid printing ink)
The liquid printing ink of the present invention can be obtained by dispersing a mixture of a binder resin, an organic solvent, and other additives using a dispersing machine, and stirring and mixing the mixture. As a dispersing machine, a bead mill, an Eiger mill, a sand mill, a gamma mill, an attritor, etc., which are commonly used in the production of gravure and flexo printing inks, are used.

(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., and can be used for printing on electronic engraving intaglio etc. While it is useful as an ink for gravure printing using a gravure printing plate made by a company, or for flexo printing using a flexo printing plate made of a resin plate, etc., it is also useful as an ink for an inkjet method in which ink is ejected from an inkjet nozzle without using a plate. This excludes ink. That is, in the case of inkjet ink, ink droplets ejected from a nozzle directly adhere to the base material and form printed matter, whereas with 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, dried to form 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.

If the liquid printing ink of the present invention is used, for example, a laminate having at least a first printing layer and a second printing layer in this order on a paper base material, the first printing layer is a layer in which the liquid printing ink is used. It is possible to create a laminate in which the second printing layer is a printing layer of reflective metal ink such as silver ink. Further, an overprint varnish may be provided on the second printing layer as necessary.
Specifically, for example, on coated paper as printing paper, using a gravure printing machine equipped with a gravure plate with a plate depth of 175 L/inch, print the liquid printing ink of the present invention and silver ink as high brightness ink in that order, A laminate can be obtained. Furthermore, an oil-based or water-based overprint varnish may be printed on the laminate.

Reflective metallic inks applied to porous and non-smooth substrates, such as paper substrates, penetrate and soak into the porous substrate and dry in a non-smooth layer that follows the non-smooth surface contours of the substrate, resulting in , resulting in a low-intensity print appearance with low reflectivity. Use of the liquid ink of the present invention as a primer is recommended to prevent penetration of high-brightness inks, control the orientation of vapor-deposited aluminum pigments, and help improve brightness.

Printing substrates on which the liquid printing ink of the present invention is printed include, for example, high-quality paper, coated paper, art paper, used for printing packages for cigarette packaging, confectionery, cosmetics, beverages, pharmaceuticals, toys, electronic parts, etc. Paper base materials such as imitation paper, thin paper, cardboard, various synthetic papers, etc. are preferred, but polyester resins, acrylic resins, vinyl chloride resins, vinylidene chloride resins, polyvinyl alcohol, polyethylene, polypropylene, polyacrylonitrile, and ethylene vinyl acetate are also preferred. Laminated using films or sheets of polymers, ethylene vinyl alcohol copolymers, ethylene methacrylic acid copolymers, nylon, polylactic acid, polycarbonate, etc., cellophane, aluminum foil, and other base materials conventionally used as printing base materials. It is possible to create a body.

The present invention will be explained in more detail with reference to Examples below. In the examples, "parts" and "%" represent "parts by mass" and "% by mass," respectively.
In the present invention, the weight average molecular weight (in terms of polystyrene) was measured by GPC (gel permeation chromatography) using HLC8220 system manufactured by Tosoh Corporation under the following conditions.
Separation columns: Four TSKgelGMHHR-N manufactured by Tosoh Corporation were used. Column temperature: 40°C. Mobile layer: Tetrahydrofuran manufactured by Wako Pure Chemical Industries, Ltd. Flow rate: 1.0ml/min. Sample concentration: 1.0% by mass. Sample injection volume: 100 microliters. Detector: Differential refractometer.
In addition, the glass transition temperature (Tg) was measured using a differential scanning calorimeter (“DSC Q100” manufactured by TA Instruments Co., Ltd.) under a nitrogen atmosphere using a cooling device in the temperature range of -80 to 450°C and increasing the temperature. The scanning was performed at 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, polyvinyl alcohol component 19.5%), 40 parts of isopropyl alcohol, and 40 parts of methyl ethyl ketone. Using a diluting solvent as a viscosity adjusting solvent, the obtained liquid printing ink was transferred to Zahn Cup No. 1 manufactured by Rigosha. The viscosity was adjusted to 18 seconds (25° C.) at No. 3. Note that isopropyl alcohol: methyl ethyl ketone = 50:50 (mass ratio) was used as a 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 Preparation Example 1. A liquid printing ink was prepared using the same formulation and procedure as in Preparation Example 1.

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

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

[Adjustment example 5]
20 parts of polyvinyl butyral resin A (Tg 63°C, polyvinyl alcohol component 19.5%), Marquid NO. 31 (manufactured by Arakawa Chemical Industries, Ltd.), 36 parts of isopropyl alcohol, and 40 parts of methyl ethyl ketone were mixed and stirred to prepare a liquid printing ink. Using a diluting solvent as a viscosity adjusting solvent, the obtained liquid printing ink was transferred to Zahn Cup No. 1 manufactured by Rigosha. The viscosity was adjusted to 18 seconds (25° C.) at No. 3. Note that isopropyl alcohol: methyl ethyl ketone = 50:50 (mass ratio) was used as a diluting solvent.

[Adjustment example 6]
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 TEGOVARI PLUS CA (manufactured by Evonik Japan Co., Ltd.) as a ketone resin, 36 parts of isopropyl alcohol, and 40 parts of methyl ethyl ketone. did. Using a diluting solvent as a viscosity adjusting solvent, the obtained liquid printing ink was transferred to Zahn Cup No. 1 manufactured by Rigosha. The viscosity was adjusted to 18 seconds (25° C.) at No. 3. Note that isopropyl alcohol: methyl ethyl ketone = 50:50 (mass ratio) was used as a 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 Alkydia 1308E (manufactured by DIC Corporation) as an alkyd resin, 36 parts of isopropyl alcohol, and 40 parts of methyl ethyl ketone. . Using a diluting solvent as a viscosity adjusting solvent, the obtained liquid printing ink was transferred to Zahn Cup No. 1 manufactured by Rigosha. The viscosity was adjusted to 18 seconds (25° C.) at No. 3. Note that isopropyl alcohol: methyl ethyl ketone = 50:50 (mass ratio) was used as a diluting solvent.

[Adjustment example 8]
20 parts of polyvinyl butyral resin A (Tg 63°C, polyvinyl alcohol component 19.5%), industrial nitrified cotton L1/8 (nitrocellulose, solid content 70%, viscosity 1.0 at a solution concentration of 25.0% according to JIS K-6703). A primer was prepared by mixing and stirring 4 parts of 6% to 2.9% product (manufactured by Taihei Chemical Products Co., Ltd.), 36 parts of isopropyl alcohol, and 40 parts of methyl ethyl ketone. Using a diluting solvent as a viscosity adjusting solvent, the obtained liquid printing ink was transferred to Zahn Cup No. 1 manufactured by Rigosha. The viscosity was adjusted to 18 seconds (25° C.) at No. 3. Note that isopropyl alcohol: methyl ethyl ketone = 50:50 (mass ratio) was used as a diluting solvent.

[Adjustment example 9]
30 parts of industrial nitrified cotton L1/8 (nitrocellulose, solid content 70%, viscosity 1.6 to 2.9% at a solution concentration of 25.0% according to JIS K-6703, manufactured by Taihei Chemical Products Co., Ltd.), isopropyl alcohol A nitrocellulose solution was prepared by mixing and stirring 20 parts of ethyl acetate and 50 parts of ethyl acetate. Using a diluting solvent as a viscosity adjusting solvent, the obtained nitrocellulose solution was transferred to Zahn Cup No. 1 manufactured by Rigosha. The viscosity was adjusted to 18 seconds (25° C.) at No. 3. Note that isopropyl alcohol:ethyl acetate=30:70 (mass ratio) was used as a 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 Roam and Haas Company), 40 parts of methyl ethyl ketone, and 40 parts of toluene. Using a diluting solvent as a viscosity adjusting solvent, the obtained acrylic resin solution was transferred to Zahn Cup No. 1 manufactured by Rigosha. The viscosity was adjusted to 18 seconds (25° C.) at No. 3. Note that methyl ethyl ketone:toluene=50:50 (mass ratio) was used as a diluent solvent.

[Adjustment example 11]
A salt vinyl acetate resin solution was prepared by mixing and stirring 20 parts of Solvine A (vinyl chloride vinyl acetate resin, Tg: 76°C, manufactured by Nissin Chemical Industry Co., Ltd.), 50 parts of methyl ethyl ketone, and 30 parts of n-propyl acetate. The obtained vinyl chloride vinyl acetate resin solution was heated using a diluting solvent as a viscosity-adjusting solvent, using a Zahn cup No. manufactured by Rigosha. The viscosity was adjusted to 18 seconds (25° C.) at No. 3. Note that methyl ethyl ketone: normal propyl acetate = 75:25 (mass ratio) was used as a diluting solvent.

[Preparation of silver ink]
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 Chemical Products Co., Ltd.) 6 parts, isopropyl alcohol After mixing and stirring 6 parts of ethyl acetate and 48 parts of ethyl acetate to prepare a nitrocellulose solution, 40 parts of a vapor-deposited aluminum pigment (manufactured by BASF, "Metasheen 11-0010", average particle size: 10 μm, non-volatile content: 10% by mass) was mixed. A silver ink for overprinting was prepared by stirring. Using a diluting solvent as a viscosity adjusting solvent, the obtained silver ink was coated with Zahn Cup No. 1 manufactured by Rigosha. The viscosity was adjusted to 18 seconds (25° C.) at No. 3. Note that ethyl acetate: normal propyl acetate = 50:50 (weight ratio) was used as a diluting solvent.

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

[Examples 2 to 8]
In place of the liquid printing ink obtained in Preparation Example 1 of Example 1, the liquid printing inks obtained in Preparation Examples 2 to 8 and the silver ink were printed in that order, and the printed matter was designated as Examples 2 to 8, respectively. .

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

[Comparative Examples 2 to 4]
In place of the liquid printing ink obtained in Preparation Example 1 of Example 1, the liquid printing inks obtained in Preparation Examples 9 to 11 and the silver ink were printed in that order, and the printed matter was designated as Comparative Examples 2 to 4, respectively. .

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

[Evaluation item 1: Glossiness]
Regarding the metallic appearance of the printed matter, the glossiness at 20° and 60° was measured in accordance with JIS Z 8741 using a specular gloss meter (manufactured by BYK-Gardner, "micro-TRI-gloss"). The higher the gloss value, the higher the gloss and the better the glitter.

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

(Evaluation criteria)
○: The transferability of the silver ink is good, and the plain area of the base paper is hardly seen. △: The transferability of the silver ink is slightly poor, and less than 20% of the plain area is seen.
Within the practical range ×: The transferability of silver ink is poor, and 20% or more of the plain area is observed.

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

(Evaluation criteria)
○: 50% or more of the silver ink film is peeled off from the paper coating layer, and paper fibers are visible.
Δ: Less than 50% of the silver ink film was peeled off from the paper coating layer, and paper fibers were visible, but within the practical range.
×: The silver ink film peels off, but it does not peel off from the coating layer, and the paper fibers are not visible.

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

The liquid printing ink of the present invention can have adhesion to the substrate, brightness due to high gloss, and sufficient concealment of the printed part in printed matter overprinted with silver ink.

Claims (4)

A laminate having at least a first printed layer and a second printed layer in this order on a paper base material, wherein the first printed layer contains a binder resin and an organic solvent, and the binder resin is polyvinyl acetal. 1. A laminate comprising a printed layer of liquid printing ink which is a resin, and wherein the second printed layer is a printed layer of reflective metal ink. In the liquid printing ink, 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 based on the total resin. The laminate according to claim 1. The laminate according to claim 1 or 2 , wherein the liquid printing ink further contains a rosin resin. The laminate according to any one of claims 1 to 3, wherein the printed layer is a printed layer formed by flexographic printing or gravure printing.