JP5912565B2 - Printing ink composition for laminate cans - Google Patents

Description

The present invention relates to a printing ink composition for laminate cans, and more particularly to a printing ink composition for laminate cans excellent in adhesion (laminating suitability) of a printed matter after retorting to the can.

Metal cans made of steel, aluminum, and the like have high oxygen barrier properties and light shielding properties, and are excellent in strength. Therefore, they have been used as containers for various beverages and foods regardless of liquid or solid. The metal can includes a three-piece can with a top cover, a bottom cover, and a body part composed of three separate parts, and a two-piece structure composed of two parts: a body part integrally molded with the bottom cover and the can body, and a top cover. There is a can. Most of the 3-piece cans are made of steel, and the flat plate-shaped body is rounded into a cylinder, the ends are welded together, and the top and bottom lids are stacked and wrapped around the outside of the body. Although the can operation is complicated, there is an advantage that it is sturdy and hardly deformed. On the other hand, the two-piece can has the advantage that it can be easily made because it can omit the work of processing the body and attaching the bottom lid. Taking advantage of both of these advantages, traditionally three-pieces that are not easily deformed at atmospheric pressure, such as tea or coffee, where the inside of the can has a negative pressure when it is filled hot and cooled. When the can has a high internal pressure such as carbonated drinks or beer, a two-piece can is mainly used.

Since metal cans have high oxygen barrier properties and light shielding properties, their contents are rarely altered even when compared with plastic bottles and the like. However, contrary to that, the inside of the can cannot be confirmed from the outside, so there is a problem that the contents cannot be understood as it is. Therefore, in order for manufacturers such as beverages to differentiate their products by appearance, it is necessary to provide an exterior to the can. Ordinarily, the exterior of metal cans not only displays the contents but also makes the contents feel more attractive as a result of focusing on how consumers can appeal and select their products. Is given. The main components of this decoration are printing of multicolor ink and resin coating for making the surface glossy or matte. Printing ink dedicated to the can is used for printing the metal can, and an overcoat agent for the outer surface of the can is used for the resin coating. Printing ink printing and overcoat agent coating are performed directly on the outer surface of the metal can. However, when printing ink is printed on the curved surface after making the can, work efficiency is reduced. Work is performed when the body is flat plate-like.

However, when the material is a steel plate (steel plate), it is difficult to perform precise printing with a high-speed winding method. Therefore, usually, when printing on steel plates, the printing steel is cut for each color by an offset printing method in which a steel plate is cut into a sheet shape with an area that allows multiple chamfering and then printed using a soft material such as a blanket. A method of printing and finally applying an overcoat agent for the outer surface of the can was used. However, this method has a problem that printing and coating are very inefficient.

Also, printing inks and overcoat agents have a tough coating that prevents the outer surface of the can from being scratched even if the printed or coated can is handled violently by loading it into a vending machine. A baked type resin is used. Therefore, when such a baking type resin is used, there has been a problem that much energy and time are required for drying and curing (baking) of the printing ink and the overcoat agent.

Therefore, in recent years, a laminated steel plate is used in which a plastic film such as polyester, which is preprinted with printing ink by a gravure method or the like, is bonded to the outer surface of a metal plate via an adhesive on the outer surface of the steel plate serving as a body portion. The method has been put into practical use. The can obtained by this method is also called a laminate can, and since a high-speed winding method can be used as a method of printing ink on a plastic film, a steel sheet supplied in a coil shape and a printed plastic film are used. When laminating, it is possible to perform a series of operations without cutting the steel sheet into a sheet, and the work efficiency until finally obtaining the laminated steel sheet is improved. In addition, the printing surface printed with printing ink is laminated so that it is sandwiched between the steel plate and the base film, and the base film on the outermost side acts as a protective layer for the printing surface. It does not have to be formed. In addition, since the printed surface seen through the base film exhibits a high gloss feeling, no overcoat agent is required.

As the colorant contained in the printing ink composition, a colorant called a high-brightness pigment such as an aluminum paste, a pearl pigment, or aluminum powder is used so that an excellent decorative effect can be obtained (for example, Patent Documents). 1, see Patent Document 2). The use of high-intensity pigments makes the printed material look very good and allows decoration to make the contents more attractive.
However, a laminated can obtained using a conventional high-intensity pigment as a colorant is filled with the contents, and then subjected to a retort treatment with hot water for sterilization, the metal surface of the can, an adhesive layer, There was a problem that the adhesion between the printing layer of the printing ink and each layer of the plastic film was likely to be lowered. In particular, when using a pearl pigment whose surface is treated with a general treatment agent such as organic fatty acid, when using a pearl pigment whose titanium oxide is coated on the surface of mica, retort treatment There was a problem that later deterioration of adhesiveness was likely to manifest.

JP-A-08-198272 JP 2003-342509 A

An object of this invention is to provide the printing ink composition for laminated cans which is excellent in the adhesiveness (laminate suitability) to the can of the printed matter after a retort process.

The present invention is a pigment, a binder resin, and, a laminate can for printing ink composition containing an organic solvent, wherein the pigment contains mica and titanium oxide and tin and zirconium oxide is coated on the front surface And the said binder resin is a printing ink composition for laminate cans containing a polyurethane resin.
The present invention is described in detail below.

As a result of intensive studies, the present inventors have used aluminum paste containing aluminum particles surface-treated with an acrylic resin, and / or mica whose surface is coated with titanium oxide, tin oxide, and zirconium oxide, and By using a polyurethane resin as the binder resin, it was found that a printed ink composition for laminate cans having excellent adhesion to a can of a printed product after retort treatment can be obtained, and the present invention has been completed.

The printing ink composition for laminate cans of the present invention contains a pigment.
The pigment contains an aluminum paste containing aluminum particles surface-treated with an acrylic resin and / or mica whose surface is coated with titanium oxide, tin oxide and zirconium oxide.

The aluminum paste is a mixture of aluminum powder and a solvent such as mineral split.
In the printing ink composition for laminate cans of the present invention, the aluminum particles constituting the aluminum powder are surface-treated with an acrylic resin. By surface-treating the aluminum particles with an acrylic resin, wettability to a binder resin containing a polyurethane resin can be improved. Therefore, a printing ink composition for a laminate can obtained by using an aluminum paste containing aluminum particles surface-treated with an acrylic resin as a pigment and using a polyurethane resin as a binder resin is used for a printed product after retorting. Excellent adhesion.

As an aluminum paste containing the aluminum particle surface-treated with the said acrylic resin, what is marketed from Toyo Aluminum Co., Ltd., Asahi Kasei Chemicals Co., Ltd., etc. is mentioned, for example.

The preferable lower limit of the average particle diameter of the aluminum particles is 5 μm, and the preferable upper limit is 50 μm. If the average particle size of the aluminum particles is less than 5 μm, the brightness of the printed matter may be insufficient. When the average particle diameter of the aluminum particles exceeds 50 μm, clogging of the plate may occur when the obtained printing ink composition for laminate cans is printed by the gravure method. A more preferable upper limit of the average particle diameter of the aluminum particles is 35 μm.
In the present specification, the average particle diameter can be determined by measuring by a method such as a Coulter counter method using electrical resistance change, a laser method using light scattering, or the like.

Also, a printing ink composition for laminate cans obtained by using mica (hereinafter also referred to as pearl pigment) whose surface is coated with titanium oxide, tin oxide and zirconium oxide as a pigment and using a polyurethane resin as a binder resin. The product also has excellent adhesion to the can of the printed product after the retort treatment. The pearl pigment is preferably coated with tin oxide and zirconium oxide after the surface of mica is coated with titanium oxide.

The preferable lower limit of the average particle diameter of the pearl pigment is 5 μm, and the preferable upper limit is 50 μm. When the average particle size of the pearl pigment is less than 5 μm, the brightness of the printed matter may be insufficient. When the average particle diameter of the pearl pigment exceeds 50 μm, clogging of the plate may occur when the obtained printing ink composition for laminate cans is printed by the gravure method. A more preferable upper limit of the average particle diameter of the pearl pigment is 35 μm.

The minimum with preferable content (solid content) of the said pigment in the printing ink composition for laminate cans of this invention is 1 mass%, and a preferable upper limit is 40 mass%. When the content of the pigment is less than 1% by mass, the color density of the printed matter may be lowered. When content of the said pigment exceeds 40 mass%, the viscosity of the printing ink composition for laminate cans may become high. The minimum with more preferable content of the said pigment is 5 mass%, and a more preferable upper limit is 20 mass%.

The printing ink composition for laminate cans of the present invention contains a binder resin. The binder resin contains a polyurethane resin.
As the polyurethane resin, a polyurethane resin obtained by synthesizing a urethane prepolymer by reaction of an organic diisocyanate compound and a polymer diol compound and reacting with a chain extender and a reaction terminator as necessary is suitably used. it can.

Examples of the organic diisocyanate compound include aromatic diisocyanate compounds such as tolylene diisocyanate, alicyclic diisocyanate compounds such as 1,4-cyclohexane diisocyanate and isophorone diisocyanate, aliphatic diisocyanate compounds such as hexamethylene diisocyanate, α , Α, α ′, α′-tetramethylxylylene diisocyanate and other aromatic aliphatic diisocyanate compounds. Of these, alicyclic diisocyanate compounds, aliphatic diisocyanate compounds, and araliphatic diisocyanate compounds are preferred. These organic diisocyanate compounds may be used alone or in combination of two or more.

Examples of the polymer diol compound include polyalkylene glycols such as polyethylene glycol and polypropylene glycol, polyether diols such as an alkylene oxide adduct of bisphenol A, and two types such as adipic acid, sebacic acid, and phthalic anhydride. One or more basic acids and one or more glycols such as ethylene glycol, propylene glycol, 1,4-butanediol, neopentyl glycol, 3-methyl-1,5-pentanediol, and the like Polyester diols obtained by condensation reaction of polyester diol, polyester diol compounds such as polycaprolactone diol, and the like. Especially, since the obtained printing ink composition for laminate cans becomes the thing excellent in the adhesiveness after a retort process, a polyesterdiol compound is preferable. These polymer diol compounds may be used alone or in combination of two or more. The organic solvent used in the printing ink composition for laminate cans is an ester organic solvent and an alcohol. In the case of a mixed solvent of an organic solvent, it is preferable to use a polyether diol compound and a polyester diol compound as the polymer diol compound from the viewpoint of the solubility of the resulting polyurethane resin.

Further, in addition to the above polymer diol compound, 1,4-pentanediol, 2,5-hexanediol, 3-methyl-1,5-pentanediol, ethylene glycol, propylene glycol, 1,4-butanediol, 1 , 3-butanediol and other low molecular diol compounds can be used alone or in admixture of two or more.

As the use ratio of the organic diisocyanate compound and the high molecular diol compound or the mixture of the high molecular diol compound and the low molecular diol compound, the equivalent ratio of isocyanate groups to 1 equivalent of hydroxyl groups (hereinafter also referred to as isocyanate index) A preferred lower limit is 1.2 and a preferred upper limit is 3.0. If the isocyanate index is less than 1.2, the resulting polyurethane resin may have insufficient hardness and may need to be used in combination with another hard resin. A more preferable lower limit of the isocyanate index is 1.3, and a more preferable upper limit is 2.0.

As the chain extender, known chain extenders used for polyurethane resins can be used, specifically, for example, aliphatic diamines such as ethylenediamine, propylenediamine, tetramethylenediamine, hexamethylenediamine, Cycloaliphatic diamines such as isophorone diamine and 4,4'-dicyclohexylmethane diamine, aromatic diamines such as toluylenediamine, araliphatic diamines such as xylene diamine, N- (2-hydroxyethyl) Diamines having a hydroxyl group such as ethylenediamine, N- (2-hydroxyethyl) propylenediamine, N, N′-di (2-hydroxyethyl) ethylenediamine, ethylene glycol, propylene glycol, 1,4-butanediol, neopentyl Glycol, diethylene glycol Diol compounds such as triethylene glycol, and the like. Furthermore, polyamines such as diethylenetriamine and triethylenetetramine can be used in combination as the chain extender as long as the polyurethane resin does not gel.

As the reaction terminator, known reaction terminators used for polyurethane resins can be used. Specifically, for example, monoalkylamines such as n-propylamine and n-butylamine, di-n- Examples thereof include dialkylamines such as butylamine, alkanolamines such as monoethanolamine and diethanolamine, and monoalcohols such as ethanol.

A polyurethane resin can be obtained by a known method for producing a polyurethane resin using the above material. Also, if the molecular weight, chemical structure and equivalent ratio of the components constituting each material are different, the physical properties such as hardness of the resulting polyurethane resin will also be different. It is possible to adjust the adhesion after retorting.

The preferable lower limit of the mass average molecular weight of the polyurethane resin is 10,000, and the preferable upper limit is 100,000. If the mass average molecular weight of the polyurethane resin is less than 10,000, the drying property, blocking resistance, and film strength of the printing ink composition for laminate cans may be lowered. If the mass average molecular weight of the polyurethane resin exceeds 100,000, the viscosity of the printing ink composition for laminate cans increases, and the gloss of the printed film may decrease. The minimum with a more preferable mass average molecular weight of the said polyurethane resin is 20,000, and a more preferable upper limit is 80,000.
In addition, in this specification, the said mass mean molecular weight is a value calculated | required by polystyrene conversion by measuring with gel permeation chromatography (GPC).
Examples of the apparatus for measuring the mass average molecular weight in terms of polystyrene by GPC include Water 2690 (manufactured by Waters) and PLgel 5μ MIXED-D (manufactured by Polymer Laboratories) as a column.

The minimum with preferable content of the said polyurethane resin in the printing ink composition for laminate cans of this invention is 5 mass%, and a preferable upper limit is 20 mass%. When the content of the polyurethane resin is less than 5% by mass, the obtained printing ink composition for laminate cans may be inferior in adhesiveness. When content of the said polyurethane resin exceeds 20 mass%, the viscosity of the printing ink composition for laminate cans may become high.

From the viewpoint of the dispersibility of the pigment in the printing ink composition for laminate cans and the blocking resistance after printing on the base film, the binder resin is a vinyl chloride-vinyl acetate copolymer, polyurethane resin: vinyl chloride. -It is preferable to contain in the quantity used as the mass ratio of vinyl acetate copolymer = 50: 50-95: 5. When the mass ratio of the vinyl chloride-vinyl acetate copolymer exceeds the mass ratio of the polyurethane resin, the suitability of the laminate after the retort treatment may be deteriorated.

The vinyl chloride-vinyl acetate copolymer has a chemical resistance, toughness, adhesiveness, solubility, etc. that change depending on the molar ratio of vinyl chloride and vinyl acetate, the degree of polymerization, and the molecular weight. It is preferable to appropriately select a vinyl chloride-vinyl acetate copolymer that optimizes the ink performance depending on the material constituting the composition.
Among the above vinyl chloride-vinyl acetate copolymer resins, those commercially available include, for example, SOLBIN C, SOLBIN CL, SOLBIN CH, SOLBIN CN, SOLBIN C5R, SOLBIN A, SOLBIN AL, SOLBIN TA2, SOLBIN TA3, SOLBIN TAO, SOLBIN TA5R, SOLBIN M, SOLBIN ME, SOLBIN MFK (all manufactured by Nissin Chemical Industry), VINNOL E14 / 45, VINNOL H14 / 36, VINNOL H40 / 55, VINNOL E15 / 45M (all, WACKER Etc.). In the case where toluene is not used as the organic solvent, it is preferable to use a vinyl chloride-vinyl acetate copolymer resin having a hydroxyl group from the viewpoint of the solubility of the vinyl chloride-vinyl acetate copolymer.

Examples of the organic solvent include ketone organic solvents such as acetone, methyl ethyl ketone, and methyl isobutyl ketone, ester organic solvents such as methyl acetate, ethyl acetate, n-propyl acetate, n-butyl acetate, and isobutyl acetate, methanol, Examples include alcohol organic solvents such as ethanol, n-propanol, isopropanol and butanol, and hydrocarbon organic solvents such as toluene and methylcyclohexanone. In particular, in consideration of recent environmental problems, a mixed solvent of an ester organic solvent and an alcohol organic solvent, a mixed solvent of an ester organic solvent, an alcohol organic solvent and a ketone organic solvent, toluene and an ester organic solvent A mixed solvent of an alcohol organic solvent and a ketone organic solvent is preferable, and a mixed solvent of an ester organic solvent and an alcohol organic solvent is more preferable.

The printing ink composition for laminate cans of the present invention may further contain various additives such as a tackifier, a crosslinking agent, a lubricant, an anti-blocking agent, an antistatic agent, and a surfactant.

The printing ink composition for laminate cans of the present invention is prepared by dispersing and kneading pigments, binder resins, organic solvents, and additives such as tackifiers to be added as necessary using a known dispersing and kneading apparatus. Can be manufactured.

As a method of printing the printing ink composition for laminate cans of the present invention on a substrate for printing, the printing ink composition for laminate cans of the present invention is specifically designed to have an appropriate viscosity at the time of printing. It is possible to use a method of diluting with an organic solvent until the outflow coefficient of No. 3 is about 14 to 18 seconds, and about 14 to 16 seconds for high-speed printing, and printing by a general gravure printing method using a printing plate.
As the printing plate, an intaglio plate produced by a normal gravure plate making method can be used. Examples of the plate making method of the printing plate include engraving gravure and the like.

As a substrate for printing on which the printing ink composition for laminate cans of the present invention is printed, a plastic film such as a polyester film, a nylon film, a polyethylene film, and a polypropylene film can be used. Because of its excellent adhesiveness, a polyester film and a nylon film can be preferably used.
The thickness of the printing substrate is usually about 5 to 50 μm.

The printing substrate on which the printing ink composition for laminate cans of the present invention is printed can be bonded to a metal plate via an adhesive.
Specifically, known coating means such as spray coating, roll coating, gravure coating, etc. on the printing surface of a printing substrate such as a plastic film on which the printing ink composition for laminate cans of the present invention has been printed by the above printing method. The adhesive is applied at a temperature of 150 to 200 ° C. and dried at a temperature of 150 to 200 ° C., and the obtained printing ink layer and the printing substrate having the adhesive layer are bonded to a metal plate and short at a temperature of about 100 to 250 ° C. By laminating for a time, the substrate for printing on which the printing ink composition for laminate cans of the present invention is printed can be bonded to a metal plate.

Examples of the adhesive include a one-component or two-component polyester resin adhesive, a polyurethane resin adhesive, and an epoxy resin adhesive.

As the metal plate, hot rolled steel plate, cold rolled steel plate, hot dip galvanized steel plate, electrogalvanized steel plate, iron-zinc alloy plated steel plate, zinc-aluminum alloy plated steel plate, nickel-zinc alloy plated steel plate, nickel-tin alloy plated Various steel plates such as steel plate, tinplate, chrome plated steel plate, aluminum plated steel plate, turn plated steel plate, nickel plated steel plate, stainless steel, tin-free steel, aluminum plate, steel plate, titanium plate, etc. As these metal materials, for example, those subjected to chemical conversion treatment such as phosphate treatment, chromate treatment, and composite oxide film treatment can be used.

By using a metal plate bonded with a printing base material on which the printing ink composition for a laminating can of the present invention is printed, a laminated can excellent in the adhesiveness of the printed matter after the retort treatment can be produced.

ADVANTAGE OF THE INVENTION According to this invention, the printing ink composition for laminate cans which is excellent in the adhesiveness (laminate suitability) to the can of the printed matter after a retort process can be provided.

Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited only to these examples. Unless otherwise specified, “%” means “% by mass”, and “part” means “part by mass”.

(Polyurethane resin varnish A)
In a four-necked flask equipped with a stirrer, a condenser tube and a nitrogen gas introduction tube, 100 parts by mass of 3-methyl-1,5-pentylene adipate diol having a mass average molecular weight of 2000, 100 parts by mass of polypropylene glycol having a mass average molecular weight of 2000, and Then, 44.4 parts by mass of isophorone diisocyanate was charged and reacted at 100 to 105 ° C. for 6 hours while introducing nitrogen gas. The mixture was allowed to cool to near room temperature, 244 parts by mass of toluene, 244 parts by mass of ethyl acetate and 121 parts by mass of n-propyl alcohol were added, and then 15.6 parts by mass of isophoronediamine was added to extend the chain. The reaction was stopped by adding 1 part by mass to obtain a polyurethane resin varnish A having a weight average molecular weight of 30,000 (solid content: 30% by mass).
(Polyurethane resin varnish B)
In a four-necked flask equipped with a stirrer, a condenser tube and a nitrogen gas introduction tube, 100 parts by mass of 3-methyl-1,5-pentylene adipate diol having a mass average molecular weight of 2000, 100 parts by mass of polypropylene glycol having a mass average molecular weight of 2000, and Then, 44.4 parts by mass of isophorone diisocyanate was charged and reacted at 100 to 105 ° C. for 6 hours while introducing nitrogen gas. The mixture was allowed to cool to near room temperature, 518 parts by mass of ethyl acetate and 91 parts by mass of n-propyl alcohol were added, then 15.6 parts by mass of isophoronediamine was added to extend the chain, and 1.1 parts by mass of monoethanolamine was further added. In addition, the reaction was stopped to obtain a polyurethane resin varnish B (solid content: 30% by mass) having a weight average molecular weight of 30,000.
(Vinyl chloride-vinyl acetate copolymer)
Vinyl chloride-vinyl acetate copolymer having hydroxyl groups (vinyl chloride resin)
(Aluminum paste)
Aluminum paste containing aluminum particles surface-treated with acrylic resin and a solvent (average particle size 7 μm, solid content 50%)
Aluminum paste containing aluminum particles and a solvent that have not been surface-treated (average particle size 10 μm)
(Pearl pigment)
Mica whose surface is coated with titanium oxide, tin oxide and zirconium oxide (average particle size 10μm)
Mica whose surface is coated only with titanium oxide (average particle size 10μm)
(Organic solvent)
Mixed solvent A (toluene: ethyl acetate: n-propyl alcohol = 40: 40: 20)
Mixed solvent B (ethyl acetate: n-propyl alcohol = 85: 15)

( Reference Example 1)
Disperse the mixture obtained by mixing 10 parts by weight of aluminum paste (solid content 50%) containing aluminum particles surface-treated with acrylic resin, 33 parts by weight of polyurethane resin varnish A, and 57 parts by weight of mixed solvent A. And the printing ink composition for laminate cans of Reference Example 1 was obtained.

( Reference Example 2)
10 parts by mass of an aluminum paste (solid content 50%) containing aluminum particles surface-treated with an acrylic resin and a solvent, 20 parts by mass of a polyurethane resin varnish A, 4 parts by mass of a vinyl chloride-vinyl acetate copolymer having a hydroxyl group, and The mixture obtained by mixing 66 parts by mass of the mixed solvent A was stirred with a disper to obtain a printing ink composition for laminate cans of Reference Example 2.

( Reference Example 3)
Mixture obtained by mixing 10 parts by mass of aluminum paste (solid content 50%) containing aluminum particles surface-treated with acrylic resin, 33 parts by mass of polyurethane resin varnish B, and 57 parts by mass of mixed solvent B Was stirred with a disper to obtain a printing ink composition for laminate cans of Reference Example 3.

( Reference Example 4)
10 parts by mass of aluminum paste (solid content 50%) containing aluminum particles surface-treated with an acrylic resin and a solvent, 20 parts by mass of polyurethane resin varnish B, 4 parts by mass of a vinyl chloride-vinyl acetate copolymer having a hydroxyl group, and The mixture obtained by mixing 66 parts by mass of the mixed solvent B66 was stirred with a disper to obtain a printing ink composition for laminate cans of Reference Example 4.

(Comparative Example 1)
A mixture obtained by mixing 10 parts by mass of aluminum paste (solid content 50%) containing aluminum particles not subjected to surface treatment, 33 parts by mass of polyurethane resin varnish A, and 57 parts by mass of mixed solvent A The mixture was stirred with a disper to obtain a printing ink composition for laminate cans of Comparative Example 1.

(Comparative Example 2)
10 parts by mass of aluminum paste (solid content 50%) containing aluminum particles not subjected to surface treatment and a solvent, 20 parts by mass of polyurethane resin varnish A, 4 parts by mass of vinyl chloride-vinyl acetate copolymer having a hydroxyl group, and The mixture obtained by mixing 66 parts by mass of mixed solvent A was stirred with a disper to obtain a printing ink composition for laminate cans of Comparative Example 2.

(Example 5)
A mixture obtained by mixing 10 parts by mass of mica coated with titanium oxide, tin oxide and zirconium oxide on the surface, 33 parts by mass of polyurethane resin varnish A, and 57 parts by mass of mixed solvent A was stirred with a disper. No. 5 printing ink composition for laminate cans was obtained.

(Example 6)
10 parts by mass of mica coated with titanium oxide, tin oxide and zirconium oxide on the surface, 20 parts by mass of polyurethane resin varnish A, 4 parts by mass of vinyl chloride-vinyl acetate copolymer having a hydroxyl group, and 66 parts by mass of mixed solvent A The mixture obtained by mixing was stirred with a disper to obtain a printing ink composition for laminate cans of Example 6.

(Example 7)
A mixture obtained by mixing 10 parts by mass of mica whose surface was coated with titanium oxide, tin oxide and zirconium oxide, 33 parts by mass of polyurethane resin varnish B, and 57 parts by mass of mixed solvent B was stirred with a disper. No. 7 printing ink composition for laminate cans was obtained.

(Example 8)
10 parts by mass of mica coated with titanium oxide, tin oxide and zirconium oxide on the surface, 20 parts by mass of polyurethane resin varnish B, 4 parts by mass of vinyl chloride-vinyl acetate copolymer having a hydroxyl group, and 66 parts by mass of mixed solvent B The mixture obtained by mixing was stirred with a disper to obtain a printing ink composition for laminate cans of Example 8.

(Comparative Example 3)
A mixture obtained by mixing 10 parts by mass of mica whose surface is coated with only titanium oxide, 33 parts by mass of polyurethane resin varnish A, and 57 parts by mass of mixed solvent A was stirred with a disper, and printing for laminate can of Comparative Example 3 An ink composition was obtained.

(Comparative Example 4)
It was obtained by mixing 10 parts by mass of mica whose surface was coated only with titanium oxide, 20 parts by mass of polyurethane resin varnish A, 4 parts by mass of vinyl chloride-vinyl acetate copolymer having a hydroxyl group, and 66 parts by mass of mixed solvent A. The mixture was stirred with a disper to obtain a printing ink composition for laminate cans of Comparative Example 4.

<Evaluation>
(Printing of printing ink composition for laminate cans)
The mixed solvent A was added to the printing ink compositions for laminate cans of Reference Examples 1 to 4 and Comparative Examples 1 and 2 and diluted so that the viscosity would be 15 seconds with Zahn Cup # 3 manufactured by Koiso Co., Ltd. Similarly, the mixed solvent B is added to the printing ink compositions for laminate cans of Examples 5 to 8 and Comparative Examples 3 and 4 so that the viscosity becomes 15 seconds with Zahn Cup # 3 manufactured by Koiso Co., Ltd. did. Next, the diluted printing ink composition for each laminate can was subjected to a corona discharge treatment on one side with a gravure printing machine (manufactured by Toya Seisakusho) equipped with an engraving plate (Helio 175 line) (Toyobo Co., Ltd.). A printed PET film was obtained by printing on a treated surface of “E-5101”, 12 μm thick, hereinafter referred to as a PET film).

(Manufacture of metal plate with PET film)
A thermosetting epoxy resin adhesive was applied to the printing ink printing part for laminate cans of each printed PET film so that the dry coating film weight was 10 g / m ² and preliminarily dried. Next, a printed PET film coated with an adhesive is superposed on a tin-plated steel plate as a metal plate for cans so that the adhesive layer is in contact with the tin-plated steel plate, and a roll pressure of 4 kg / cm ² and a roll temperature of 200 ° C. are used. And a heat treatment at 210 ° C. for 2 minutes to obtain a metal plate on which a printed PET film was bonded.

(Appearance change before and after the hot water test)
Retort treatment was performed in 125 ° C. for 30 minutes of water vapor on a metal plate on which each printed PET film on which the printing ink composition for laminate cans of Reference Examples 1 to 4, Examples 5 to 8 and Comparative Examples 1 to 4 had been printed was bonded. The appearance (brightness, whitening, bubble generation, film wrinkles, etc.) was visually observed, and “○” indicates that the appearance was good as before retorting, and the appearance was poor after retorting. The appearance change before and after the hot water test was evaluated as “×”. The results are shown in Tables 1 and 2.

ADVANTAGE OF THE INVENTION According to this invention, the printing ink composition for laminate cans which is excellent in the adhesiveness (laminate suitability) to the can of the printed matter after a retort process can be provided.

Claims (4)

A printing ink composition for a laminate can containing a pigment, a binder resin, and an organic solvent,
The pigment contains mica and titanium oxide and tin and zirconium oxide is coated on the front surface,
The printing ink composition for laminate cans, wherein the binder resin contains a polyurethane resin. The binder resin contains a vinyl chloride-vinyl acetate copolymer in an amount of a mass ratio of polyurethane resin: vinyl chloride-vinyl acetate copolymer = 50: 50 to 95: 5. The printing ink composition for laminated cans as described. The printing ink composition for laminate cans according to claim 1 or 2, wherein the organic solvent is a mixed solvent of toluene, an ester organic solvent, an alcohol organic solvent, and a ketone organic solvent. The printing ink composition for laminate cans according to claim 1 or 2, wherein the organic solvent is a mixed solvent of an ester organic solvent and an alcohol organic solvent.