JPH1179174A - Printed seamless can and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a printed seamless can and its manufacture, in which roughness at lap application parts and the distortion of printed images, or the deterioration of gloss, due to steps are eliminated, and which is excellent in the fine appearance of a printed part and in a commodity value in the printed seamless can having a printed ink layer provided on an outer surface thereof and a finish varnish layer provided on the printed ink layer, whose finish varnish layer contains an ultraviolet-curable resin and has, in the circumferential direction of a can body, a single application part and lap application parts at narrow intervals. SOLUTION: This printed seamless can has a printed ink layer 4 provided on an outer surface of the can and a finish varnish layer provided on the printed ink layer 4. The finish varnish layer contains an ultraviolet-curable resin and has, in the circumferential direction of a can body, a single application part and lap application parts at narrow intervals. The degree of surface roughness of the lap application parts of the finish varnish layer is at most 0.3 μm and moreover is controlled to a degree less than double of that of the single application part.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a seamless printing can using an ultraviolet-curable paint and a method for producing the same. The present invention relates to an improved printed seamless can and a method for producing the same.

[0002]

2. Description of the Related Art Cans are roughly classified into three-piece cans having a seam on the side of the can body and tightening the top and bottom with the lid, and a bottomed can body without a seam on the side of the can body. Two types are used, namely, a two-piece can (seamless can) that performs winding between a single lid and a single lid. In any of these cans,
It is common to print on the outer surface of the can to display the content and source of the food and to enhance the commercial value.

In a three-piece can, a metal material pre-printed is used to form a seam for forming a seam. In the case of the two-piece can, the outer surface of the can body after the can is painted and printed. It is common to do In this external printing, after a printing ink layer is provided, a transparent lacquer generally called a finishing varnish or a gloss varnish is applied thereon and cured to prevent abrasion of the printing ink layer and to reduce the gloss of a printed image. I try to improve.

[0004] An ink or a coating composition containing an ultraviolet curable resin has no problem of evaporation of a solvent at the time of drying or baking, and does not require heating of the coated material. Used and is being considered for use.

[0005]

However, in the case of external printing on a seamless can, in order to prevent a non-printed portion from being generated on the can body, one end and the other end in the circumferential direction of the print pattern must be always formed. In order to prevent the printed layer from being directly exposed even when applying the finishing varnish layer to the printed section, as well as to overlap, the coating pattern is overlapped at both ends, so that the single coated section and the lap coated section at a small interval Is formed. This is because the size of the printing plate is constant, but an error of a certain range (within the allowable range) always occurs on the outer periphery of the can body of the seamless can, and the printing and the application of the finishing varnish are generally synchronized. Not necessary.

However, when a UV-curable resin containing a UV-curable resin is used as the finishing varnish and UV-curing is performed, the gloss of the cured film is reduced, and the varnish of the above-mentioned finishing varnish layer is coated with the coating layer. It was found that the roughness became extremely large, the gloss of the printing layer was reduced, and the commercial value of the printing can was significantly reduced.

Thus, an object of the present invention is to provide a printing seamless can having an outer surface provided with a printing ink layer and a finishing varnish layer thereon, wherein the finishing varnish layer contains an ultraviolet curable resin. In the case where the finish varnish layer has a single coating portion and a lap coating portion at a small interval in the circumferential direction of the can body, disturbance of a printed image due to roughness or a step in the lap coating portion or reduction in gloss is eliminated, and An object of the present invention is to provide a printed seamless can excellent in aesthetics and commercial value and a method for producing the same.

[0008]

According to the present invention, in a printing seamless can having a printing ink layer on its outer surface and a finishing varnish layer thereon, the finishing varnish layer contains an ultraviolet curable resin. In addition, the finish varnish layer has a single coating portion and a wrap coating portion at a small interval in the circumferential direction of the can body, and the surface roughness of the wrap coating portion of the finishing varnish layer is 0.3 μm or less, and the single coating portion. The present invention provides a printed seamless can characterized in that the surface roughness is suppressed to less than twice the surface roughness of the portion. According to the present invention, a printing ink layer and a finish varnish layer containing an ultraviolet-curable resin are applied to the outer surface of the seamless can, and the finish varnish layer is provided with a single coating portion and a lap coating portion at a small interval in the circumferential direction of the can body. In the method for producing a printing seamless can, which is performed so that the finishing varnish layer or the printing ink layer is ultraviolet-cured, the finishing varnish is provided with a grooved pumping roller in which diagonal fine grooves are engraved. A method for producing a printed seamless can, characterized in that the method is applied to an outer surface of a seamless can in combination with an applicator roller, and that ultraviolet curing is performed at least three seconds after the application of the roller.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION

[Operation] In FIG. 1 for explaining the occurrence of disturbance of a printed image in a seamless can, an organic resin protective layer 3 is formed on the inner surface side of a metal substrate 2 of the seamless can 1, and the outer surface side of the metal substrate 1 Has a printing ink layer 4 formed thereon, and a transparent finishing varnish layer 5 is formed on the printing ink layer 4. The printing ink layer 4 has wrap portions 6 at minute intervals to which the printing ink is applied twice, and the finishing varnish layer 5 also has a single coating portion 7 and a small interval where the finishing varnish is applied twice. And a lap coating section 8 of the wrapping section.

[0010] The lap coating unit 8 includes a single coating unit 7
However, when the finishing varnish layer is made of an ultraviolet curable resin, the thickness of the varnish layer 8 is not only increased but also the surface roughness of the lap coating portion 8 is increased. The fact that the degree of surface roughness exceeded twice the surface roughness of the single coated part 7 was confirmed.

For example, as shown in an example to be described later, when a finish varnish made of an ultraviolet curable resin is applied through a normal solid roll, the surface roughness of the single application section 6 is 0.12 μm, and the surface of the lap application section 7 is The roughness is 0.29μ
m, and in the case of a print seamless can in which the surface roughness of the lap coating section 7 exceeds twice the surface roughness of the single coating section 6, the printed image is disturbed at the lap coating section 7. The facts are clearly confirmed.

On the other hand, according to the present invention, when the surface roughness of the wrap-applied portion of the finishing varnish layer is to be 0.3 μm or less and less than twice the surface roughness of the single-applied portion, the lap coating is required. It is possible to provide a printed seamless can excellent in aesthetics and commercial value of the printing section, by suppressing the occurrence of the disturbance of the printed image and the decrease in gloss in the section 7.

In the present invention, the means for suppressing the surface roughness of the varnish-applied portion of the finishing varnish layer to the above range is not necessarily limited to this.
It is preferable that the application is performed on the outer surface of the seamless can by a combination of a grooved pumping roller and an applicator roller in which the hatched microgrooves are engraved, and ultraviolet curing is performed at least 3 seconds after the roller application.

FIG. 2 of the accompanying drawings is a graph showing the surface roughness of a lap coating portion obtained by applying a finish varnish layer to the outer surface of a seamless can and immediately curing it with an ultraviolet ray using a combination of a grooved pumping roller and an applicator roller. In contrast, FIG. 3 is a graph showing the surface roughness of a lap coating portion obtained by applying a finish varnish layer to the outer surface of a seamless can using a combination of a grooved pumping roller and an applicator roller and curing the varnish after 4 seconds. It is.

Referring to these graphs, the use of grooved pumping rollers results in a significantly greater surface roughness of the lap application formed, but the lap application after application is aged prior to UV curing. Thus, it is apparent that a surprising effect that the surface roughness of the lap coating portion can be suppressed to a remarkably low value is achieved.

This fact indicates the following. That is, the ultraviolet curable paint has a high solid content concentration, and the fine irregularities formed at the time of painting are difficult to disappear, and these minute irregularities are superimposed on the lap coating portion, and easily become large irregularities. When a grooved roller is used, rather large irregularities are generated, but these large irregularities themselves have a leveling action that attempts to smoothen, and with this action, minute irregularities in the lap coating part are also eliminated. I think that the.

[Printing and UV Curing Step] In FIG. 4 for explaining the printing step and the UV curing step in the manufacturing method of the present invention, a printing turret 11 and a curing turret 12 are arranged adjacent to each other. The seamless can 13 is rotatably held around these turrets so as to rotate and revolve. A printing unit 14 and a finishing varnish application unit 15 are arranged around the periphery of the printing turret 11, while an ultraviolet light source 16 is arranged around the periphery of the curing turret 12.

The formed and trimmed seamless can 13 is supplied to a printing turret 11 by a supply mechanism 17, and a heat-curable ink layer is applied by a printing unit 14 to an outer surface of a side wall of the turret 11, and finishing is performed on the ink layer. The varnish application unit 15 applies a finish varnish layer in a wet-on-wet relationship.

The finishing varnish application unit 15 comprises a pan 19 for containing an ultraviolet-curing finishing varnish 18, a grooved pumping roller 20 for pumping the finishing varnish, a roller 20, and an applicator roller 21 in contact with the seamless can 13.

Referring to FIG. 5 for explaining the arrangement of the grooved roller 20, the roller 20 has a hatched minute groove 22.
Are provided in parallel. The depth of the groove 22 varies depending on the viscosity of the finishing varnish, but is generally 30 to 6.
It is preferably in the range of 0 μm, especially 35 to 55 μm. Further, it is desirable that the pitch of the grooves 22 is generally in the range of 100 to 180 lines / inch, particularly 120 to 150 lines / inch. The angle of the groove 22 with respect to the axis may be in the range of 25 to 75 degrees, especially 30 to 60 degrees.
The cross-sectional shape of the groove 22 is not particularly limited, but may be any shape such as an inverted trapezoidal shape, a V shape, a U shape, and a semicircle. The material of the grooved roller is not particularly limited, but is generally formed of steel. A suitable diagonal grooved roller is available under the trade name Anilox Roller.

On the other hand, as the applicator roller 21, a solid roller made of rubber is generally used. The applicator roller having a hardness in the range of 50 ° to 70 ° is excellent in applicability.

In the present invention, the following formula (1): RL = C / L In the formula, C is a coating length of the finishing varnish, and L is a circumference of the seamless can. RL
) Is generally from 1.1 to 1.6, especially from 1.2 to 1.4
In the range. The value of RL -1 represents the ratio of the length of the lap-coated portion.

The printed seamless can 13a moves onto the curing turret 12, and is irradiated with an ultraviolet light source 16 provided therearound to cure the finished varnish layer and the ink layer. At this time, in the present invention, the ultraviolet curing is performed after the printed seamless can 13a has passed at least 3 seconds, preferably 4 to 8 seconds. The seamless can 13b having the cured film is discharged to the outside by the conveyor 25 and supplied to the next step.

[Ultraviolet Curing Finish Varnish] In the present invention, an ultraviolet curing type varnish is used as the finishing varnish. This paint contains an ultraviolet-curable resin and a catalyst, and is roughly classified into a cationically curable type and a radically polymerizable type. The present invention shows excellent effects on any of these paint systems.

(1) Cationic Curable Coating As the ultraviolet cationic polymerization coating, a combination of an ultraviolet curing epoxy resin and a photocationic polymerization catalyst is used.

The UV-curable epoxy resin includes an epoxy resin component having an alicyclic group in the molecule and an adjacent carbon atom of the alicyclic group forming an oxirane ring. For example, an epoxy compound having at least one epoxycycloalkane group, for example, an epoxycyclohexane ring, an epoxycyclopentane ring, or the like is used alone or in combination.

Suitable examples include, but are not limited to,
Vinylcyclohexene diepoxide, vinylcyclohexene monoepoxide, 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexane carboxylate, 2- (3,4-epoxycyclohexyl-5,
5-spiro-3,4-epoxy) cyclohexane-m-
Dioxane, bis (3,4-epoxycyclohexyl)
Adipate, limonenedoxide, and the like.

The cationic ultraviolet polymerization initiator used in combination with the above epoxy resin is one which is decomposed by ultraviolet rays to release a Lewis acid, and this Lewis acid has an action of polymerizing an epoxy group. An aromatic iodonium salt, an aromatic sulfonium salt, an aromatic selenium salt, an aromatic diazonium salt and the like can be mentioned.

Examples of the diallyliodonium salt include diphenyliodonium hexafluoroantimonate, diphenyliodonium hexafluorophosphate, 4-chlorophenyliodonium tetrafluoroborate, di (4-methoxyphenyl) iodonium chloride and (4-methoxyphenyl) phenyl And iodonium.

Examples of the triarylsulfonium salt include, for example, triphenylsulfonium tetrafluoroborate, triphenylsulfonium hexafluorophosphate, p- (phenylthio) phenyldiphenylsulfonium hexafluoroantimonate, triphenylsulfonium hexafluoroantimonate, 4-chloro Phenyldiphenylsulfonium hexafluorophosphate and the like.

Examples of the triarylselenium salt include triphenylselenium hexafluorophosphate, triphenylselenium hexafluoroantimonate and the like.

As other cationic polymerization initiators,
(2,4-cyclopentagen-1-yl) [(1-methoxythiethyl) -benzene] -iron-hexafluorophosphate, diphenylsulfonium hexafluoroantimonate, dialkylphenylsulfonium hexafluoroantimonate, dialkylphenylsulfonium Hexafluorophosphate, 4,4'-bis [di (β-hydroxyethoxy) phenylsulfonio]
Phenylsulfide-bis-hexafluoroantimonate, 4,4-bis [di (β-hydroxyethoxy) phenylsulfonio] phenylsulfide-bis-hexafluorophosphate and the like can be mentioned.

The cationically curable coating composition may contain a known cationically polymerizable vinyl monomer, a diluent, another epoxy resin, a sensitizer, a crosslinking agent, and the like.
As the cationic polymerizable vinyl monomer, ethylene glycol divinyl ether, ethylene glycol monovinyl ether, propylene glycol divinyl ether, propylene glycol monovinyl ether, butylene glycol monovinyl ether, hexanediol monovinyl ether, neopentyl glycol monovinyl ether, glycerol divinyl ether, Examples include glycerol trivinyl ether, trimethylolpropane divinyl ether, trimethylolpropane trivinyl ether, diglycerol trivinyl ether, sorbitol tetravinyl ether, aryl vinyl ether, and phenyl vinyl ether.

Examples of the diluent include phenylglycidyl ether, methylphenylglycidylether, n-butylglycidylether, low-viscosity compounds having an oxirane ring such as 1,2-epoxyhexadecane, ethylene glycol monoalkyl ether, propylene glycol monoalkyl ether. And polyhydric alcohol derivatives such as diethylene glycol monoalkyl ether and dipropylene glycol monoalkyl ether, and alcohols such as propanol, isopropanol, butanol and isobutanol.

Other epoxy resins for modification include bisphenol-type epoxy resins derived from bisphenols such as bisphenol A and bisphenol F and epichlorohydrin, and novolak-type phenol resins and epichlorohydrin. Novolak type epoxy resin is used.

As sensitizers, thioxanthone derivatives,
Examples include 2,4-diethylthioxanthone and 2,4-diisopropylthioxanthone.

Examples of the crosslinking agent include various polyols such as ε-caprolactone triol.

Suitable examples of formulations for cationically curable coatings include:
Although not limited thereto, the cationic UV initiator may be used in an amount of 0.5 to 10 parts by weight, particularly 1 to 5 parts by weight, a diluent 0 to 20 parts by weight, particularly 0 to 10 parts by weight, per 100 parts by weight of the alicyclic epoxy resin. 0 to 20 parts by weight, especially 0 to 15 parts by weight of another epoxy resin, 0 to 20 parts by weight, particularly 0 to 10 parts by weight of a cation polymerizable vinyl monomer, and 0 sensitizer.
To 2 parts by weight, in particular, 0 to 30 parts by weight of a crosslinking agent.

(2) Ultraviolet Radical Curable Coating As the ultraviolet radical polymerization coating, a combination of an ultraviolet curing monomer or prepolymer and a photopolymerization catalyst is used.

As the ultraviolet-curable monomer or prepolymer, a monomer or prepolymer having a plurality of ethylenically unsaturated groups in a molecule or a mixture thereof is used. Suitable examples include epoxy acrylate resin, urethane acrylate resin, thermosetting acrylic resin, thermosetting polyester resin and the like.

Examples of the epoxy acrylate resin include an adduct of a bisphenol type epoxy resin and an ethylenically unsaturated carboxylic acid such as acrylic acid or methacrylic acid, or an adduct of the bisphenol type epoxy resin and an ethylenically unsaturated polycarboxylic acid anhydride such as, for example, A reaction product with maleic anhydride, itaconic anhydride or the like is used.

As the urethane acrylate resin, a urethane acrylate resin obtained by reacting an isocyanate-terminated polyester or an isocyanate-terminated polyol with a functional group-containing acrylic monomer such as acrylic acid, methacrylic acid, hydroxyethyl (meth) acrylate, etc. Is used.

Examples of the thermosetting acrylic resin include 1,6-hexanediol diacrylate (HDDA), 1,6-hexanediol dimethacrylate (HDDMA), neopentyl glycol diacrylate, neopentyl glycol dimethacrylate, and ethylene glycol diacrylate. Acrylate (EGD
A), ethylene glycol dimethacrylate (EGDMA), polyethylene glycol diacrylate (PEGA), polyethylene glycol dimethacrylate (PEGMA), polypropylene glycol diacrylate, polypropylene glycol dimethacrylate, butylene glycol diacrylate, butylene glycol dimethacrylate, pentaerythritol diacrylate Acrylate, 1,4-butanediol diacrylate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, pentaerythritol triacrylate, dipentaerythritol hexaacrylate, tetramethylolmethanetetraacrylate, N, N, N ', N'- Acrylate of tetrakis (β-hydroxyethyl) ethylenediamine, 2,2-bis [4- (3- Taku Leroy oxy -
2-hydroxypropoxy) phenyl) propane and the like are used.

Examples of the thermosetting polyester resin include polyesters containing an ethylenically unsaturated bond in the molecule, for example, ethylenically unsaturated polycarboxylic acids such as maleic acid, fumaric acid, itaconic acid and tetrahydrophthalic acid. , Isophthalic acid, trimellitic acid, pyromellitic acid, adipic acid, sebacic acid, combinations with other acid components such as polymerized fatty acids, and ethylene glycol, diethylene glycol, propylene glycol, glycerin, neopentyl glycol, trimethylolpropane, pentane Polyester resins obtained by condensation with polyhydric alcohols such as erythritol and bisphenols are used.

The above-mentioned polyfunctional monomers or prepolymers are usually used in combination with monofunctional monomers. Such monomers include acryloyl morpholine, glycidyl acrylate (GA), glycidyl methacrylate (GMA). ), Carbitol acrylate,
Tetrahydrofurfuryl acrylate, tetrahydrofurfuryl methacrylate, dicyclopentadienyl acrylate, dihydrodicyclopentadienyl methacrylate, isobornyl acrylate, acrylamide (AA
m), methacrylamide (MAm), N-methylolacrylamide (N-MAM), N-diacetoneacrylamide (DAA
M), N-vinylpyrrolidone, maleic acid, itaconic acid,
Methyl methacrylate (MMA), ethyl acrylate (E
A), styrene (ST), acrylonitrile (AN), vinyl acetate
(VAc), vinyl toluene (VT), etc.

Further, divinylbenzene, diallyl phthalate (DAP), diallyl isophthalate, diallyl adipate, diallyl glycolate, diallyl maleate, diallyl sebacate, triallyl phosphate,
Other polyfunctional monomers such as triallyl aconitate, allyl trimellitate, allyl pyromellitic acid and the like may also be used.

Representative examples of the photoradical initiator include benzoin such as benzoin, benzoin methyl ether, benzoin ethyl ether and benzoin isopropyl ether and their alkyl ethers; acetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone, 1,1-dichloroacetophenone, 1-hydroxycyclohexylphenyl ketone, 2-hydroxycyclohexylphenyl ketone, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholino -Propane-
Acetophenones such as 1-one; anthraquinones such as 2-methylanthraquinone and 2-amylanthraquinone; 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, 2-chlorothioxanthone, and 2,4
-Thioxanthones such as diisopropylthioxanthone, ketals such as acetophenone dimethyl ketal and benzyl dimethyl ketal; benzophenones such as benzophenone and xanthones.

The photo-radical initiator can be used in combination with one or more known and known photo-polymerization accelerators such as benzoic acid or tertiary amine.

In the radical-curable paint, the photo-radical initiator is used in an amount of 0.1 to 30 parts by weight based on 100 parts by weight of the ultraviolet-curable resin.
It is preferably used in a proportion of 1 part by weight, preferably 1 to 25 parts by weight.

The UV-curable finishing varnish used in the present invention exhibits a remarkable non-Newtonian behavior, so that it is difficult to define its viscosity. However, in general, the apparent viscosity at a shear rate of 1 sec-1 has an apparent viscosity of 1 to 5000 poise (p, 20). C).

[Printing Ink] In the present invention, an ultraviolet curable ink is generally used as the printing ink. The UV-curable ink is composed of a UV-curable resin composition similar to the finish varnish described above, in which a pigment is dispersed in a vehicle.

Suitable examples of pigments are as follows. Black pigments Carbon black, acetylene black, run black, aniline black. Yellow pigment zinc yellow, cadmium yellow, yellow iron oxide, mineral fast yellow, nickel titanium yellow, navels yellow, naphthol yellow S, Hansa yellow G,
Hansa Yellow 10G, Benzidine Yellow G, Benzidine Yellow GR, Quinoline Yellow Lake, Permanent Yellow NCG, Tartrazine Lake. Orange pigments Red mouth lead, molybdenum orange, permanent orange GTR, pyrazolone orange, Vulcan orange, induslen brilliant orange RK, benzidine orange G, induslen brilliant orange GK. Red pigment Bengala, cadmium red, lead red, cadmium mercury sulfide, permanent red 4R, lithol red, pyrazolone red, watching red calcium salt, lake red D, brilliant carmine 6B, eosin lake, rhodamine lake B, alizarin lake, brilliant carmine 3B. Purple pigment Manganese purple, fast violet B, methyl violet lake. Blue pigment Navy blue, cobalt blue, alkali blue lake, Victoria blue lake, phthalocyanine blue, metal-free phthalocyanine blue, partially chlorinated phthalocyanine blue, fast sky blue, indaslen blue B
C. Green pigment chrome green, chromium oxide, pigment green B,
Malachite Green Lake, Fanal Yellow Green G. White pigments zinc white, titanium dioxide, antimony white, zinc sulfide. Extender barite powder, barium carbonate, clay, silica, white carbon, talc, alumina white. As these pigments, it is preferable to use flash pigments from the viewpoint of dispersibility. Among these pigments, those which may cause ultraviolet curing inhibition can also be used by coating the surface of the pigment particles with a resin or the like.

These pigments are generally used in an amount of 10 per ink.
It is used in an amount of up to 60% by weight.

This ink can be blended with a compounding agent known per se in a known formulation. Examples of the compounding agent for the ink include silicone oil as an antifoaming agent, a fluorine-based surfactant as a leveling agent, and silicone as a leveling agent. System surfactant,
Thickeners, thinners, etc., such as acrylic copolymers, can be used.

[Production Process of Seamless Can and Its Production]
The seamless can used in the present invention is manufactured by drawing-redrawing or drawing-ironing of a metal material or an organic-coated metal material. An organic-coated metal plate may be formed into a cup, or a metal cup may be provided with an organic coating later.However, in terms of ease and simplicity of manufacture, an organic-coated metal plate is formed into a cup. It is suitable.

As the metal plate constituting the seamless can,
Various surface-treated steel plates and light metal plates such as aluminum are used.

As the surface-treated steel sheet, a cold-rolled steel sheet is annealed and then subjected to secondary cold rolling, and one or more surface treatments such as zinc plating, tin plating, nickel plating, electrolytic chromic acid treatment, and chromic acid treatment are performed. Can be used.
An example of a suitable surface-treated steel sheet is an electrolytic chromic acid-treated steel sheet, particularly provided with a chromium metal layer of 10 to 200 mg / m ² and a chromium oxide layer of 1 to 50 mg / m ² (in terms of chromium metal). This is excellent in the combination of coating film adhesion and corrosion resistance. Another example of a surface-treated steel plate is a hard tin plate having a tin plating amount of 0.5 to 11.2 g / m ² . This tin plate is desirably subjected to chromic acid treatment or chromic acid / phosphoric acid treatment so that the amount of chromium is 1 to 30 mg / m ^{2 in} terms of metal chromium. As still another example, an aluminum-coated steel sheet subjected to aluminum plating, aluminum pressure welding, or the like is used.

As the light metal plate, an aluminum alloy plate is used in addition to a so-called pure aluminum plate. An aluminum alloy sheet excellent in corrosion resistance and workability has a Mn of 0.1.
2 to 1.5% by weight, Mg 0.8 to 5% by weight, Zn
The composition has a composition of 0.25 to 0.3% by weight, 0.15 to 0.25% by weight of Cu, and the balance of Al. It is desirable that these light metal plates have also been subjected to a chromic acid treatment or a chromic / phosphoric acid treatment such that the chromium amount becomes 20 to 300 mg / m ^{2 in} terms of chromium metal.

The thickness of the metal plate, that is, the thickness of the bottom of the can (tB)
Has a thickness of 0.10 to 0.5 mm in general, though it depends on the type of metal, the use or the size of the container, and among them, in the case of a surface-treated steel sheet, it is preferable that the thickness be 0.1 mm.
The thickness is preferably 10 to 0.3 mm, and in the case of a light metal plate, 0.15 to 0.40 mm.

The organic coating optionally provided on the metal substrate may be a thermoplastic resin, a thermosetting resin, or a composition thereof, but is preferably a thermoplastic resin. When the metal base is an aluminum base, the resin coating on the outer surface may be omitted.

As the thermoplastic resin coated on the metal plate, a crystalline thermoplastic resin is preferable, and examples thereof include polyethylene, polypropylene, ethylene-propylene copolymer, ethylene-vinyl acetate copolymer and ethylene. Olefin resin films such as acrylic ester copolymers and ionomers; polyethylene terephthalate;
Polyesters such as polybutylene terephthalate and ethylene terephthalate / isophthalate copolymer; polyamides such as nylon 6, nylon 6,6, nylon 11 and nylon 12; polyvinyl chloride; polyvinylidene chloride;

The coating layer of the thermoplastic resin contains an inorganic filler (pigment) for the purpose of concealing the metal plate and assisting the transmission of wrinkle pressing force to the metal plate during drawing and redrawing. Can be. In addition, a compounding agent for a film known per se, for example, an antiblocking agent such as amorphous silica, various antistatic agents, a lubricant, an antioxidant, and an ultraviolet absorber may be added to the film according to a known formulation. it can.

Examples of the inorganic filler include inorganic white pigments such as rutile-type or anatase-type titanium dioxide, zinc white, and gloss white; barite, precipitated barium sulfate, calcium carbonate, gypsum, precipitated silica, aerosil, talc, calcined or the like. Are white clay pigments such as unfired clay, barium carbonate, alumina white, synthetic or natural mica, synthetic calcium silicate, magnesium carbonate; black pigments such as carbon black and magnetite; red pigments such as redwood; yellow pigments such as siena Blue pigments such as ultramarine blue and cobalt blue. These inorganic fillers can be incorporated in an amount of 10 to 500% by weight, particularly 10 to 300% by weight, based on the resin.

The coating of the coated thermoplastic resin on the metal plate is carried out by a heat fusion method, dry lamination, extrusion coating method, or the like, and the adhesiveness (heat fusion property) between the coated resin and the metal plate.
When the content is insufficient, for example, a urethane-based adhesive, an epoxy-based adhesive, an acid-modified olefin resin-based adhesive, a copolyamide-based adhesive, a copolyester-based adhesive, or the like can be interposed.

The thickness of the thermoplastic resin is generally in the range of 3 to 50 μm, preferably 5 to 40 μm. In the case of heat fusion using a film, it may be unstretched or stretched.

As a particularly preferred film, a polyester mainly composed of an ethylene terephthalate unit or a butylene terephthalate unit is formed into a film by a T-die method or an inflation film-forming method. A film produced by stretching and heat setting the stretched film can be mentioned.

As the raw material polyester, polyethylene terephthalate itself can be used under the conditions of stretching, heat setting and laminating, which are extremely limited. For this purpose, it is preferable to introduce a copolymer ester unit other than ethylene terephthalate into the polyester for this purpose. It is particularly preferable to use a biaxially stretched film of a copolymerized polyester mainly composed of ethylene terephthalate units or butylene terephthalate units and containing a small amount of other ester units and having a melting point of 210 to 252 ° C. The melting point of homopolyethylene terephthalate is generally from 255 to 265 ° C.

Generally, at least 70 mol%, especially at least 75 mol%, of the dibasic acid component in the copolyester is composed of the terephthalic acid component, and at least 70 mol%, especially at least 75 mol%, of the diol component is ethylene glycol or butylene glycol. Consisting of 1 to 30 mol% of the dibasic acid component,
In particular, it is preferable that 5 to 25 mol% is composed of a dibasic acid component other than terephthalic acid.

Examples of dibasic acids other than terephthalic acid include aromatic dicarboxylic acids such as isophthalic acid, phthalic acid and naphthalenedicarboxylic acid: alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid: succinic acid, adipic acid, sebacic acid, dodecane One or a combination of two or more aliphatic dicarboxylic acids such as dionic acid, and diol components other than ethylene glycol or butylene glycol include propylene glycol, diethylene glycol,
One or more of 1,6-hexylene glycol, cyclohexane dimethanol, an ethylene oxide adduct of bisphenol A and the like can be mentioned. Of course, the combination of these comonomers must be such that the melting point of the copolyester is within the above range.

The copolyester used should have a molecular weight sufficient to form a film, for which the intrinsic viscosity (IV) is between 0.55 and 1.9 dl / g, in particular between 0.
Those in the range of 65 to 1.4 dl / g are desirable.

The stretching of the film is generally carried out at 80 to 110 ° C.
At a temperature of, the area stretching ratio is preferably in the range of 2.5 to 16.0, particularly 4.0 to 14.0.
It is good to carry out in the range of 30 ° C.

The copolyester film is preferably biaxially stretched, and the degree of biaxial orientation can be confirmed by a polarization fluorescence method, a birefringence method, a density gradient tube method, or the like.

In laminating, in order to prevent excessive crystallization, the time required for the film to be laminated to pass through the crystallization temperature range is shortened as much as possible, preferably within 10 seconds, particularly 5 seconds. To pass within. For this,
During lamination, only the metal material is heated, and the laminate is forcibly cooled immediately after laminating the film. For cooling, direct contact with cold air or cold water or pressure contact of a forcedly cooled cooling roller is used. It is to be understood that the degree of crystal orientation can be relaxed by heating the film to a temperature near the melting point during the lamination and quenching after lamination.

When an adhesive primer is used, it is generally desirable that the surface of the film be subjected to a corona discharge treatment in order to enhance the adhesion to the adhesive primer to the film. The degree of the corona discharge treatment was such that the wetting tension was 44
Desirably, it should be dyne / cm or more.

In addition, the film may be subjected to a known surface treatment for improving adhesion such as plasma treatment or flame treatment, or a coating treatment for improving adhesion such as urethane resin or modified polyester resin. .

The adhesive primer optionally provided between the polyester film and the metal material exhibits excellent adhesiveness to both the metal material and the film. A typical primer paint excellent in adhesion and corrosion resistance is a phenol epoxy paint composed of a resol type phenol aldehyde resin derived from various phenols and formaldehyde, and a bisphenol type epoxy resin, Particularly, a phenol resin and an epoxy resin are mixed in a ratio of 50: 5.
0 to 5:95 weight ratio, especially 40:60 to 10:90
Is a paint contained in a weight ratio of

The adhesive primer layer generally has a thickness of 0.3 to 5
The thickness is preferably set to μm. The adhesive primer layer may be provided in advance on a metal material or may be provided in advance on a polyester film.

The polyester layer serving as a metal coating can be provided by a so-called extrusion coat instead of being applied in the form of a biaxially stretched film. In this extrusion coating method, a web of a molten resin extruded from a die is supplied onto a heated metal substrate, and is quenched immediately after pressing by a laminating roll.

The thermosetting resin paint used for coating includes:
For example, phenol-formaldehyde resin, furan-
Formaldehyde resin, xylene-formaldehyde resin, ketone-formaldehyde resin, urea formaldehyde resin, melamine-formaldehyde resin, alkyd resin, unsaturated polyester resin, epoxy resin, bismaleimide resin, triallyl cyanurate resin, thermosetting acrylic resin, silicone Resin, oily resin, or the above-mentioned thermosetting resin and thermoplastic resin paint, for example, vinyl chloride-
Examples thereof include a vinyl acetate copolymer, a vinyl chloride-maleic acid copolymer, a vinyl chloride-maleic acid-vinyl acetate copolymer, an acrylic polymer, and a composition with a saturated polyester resin. These resin coatings may be used alone or in combination of two or more.

Among the above thermosetting resin coatings, a combination of an epoxy resin (a), a bisphenol type epoxy resin and a curing agent resin (b) for this epoxy resin is preferable.

Among these curing agent resins, a phenol-formaldehyde resin, particularly a phenol-aldehyde resin component containing a polycyclic polyphenol, is used.
It is desirable in terms of adhesion to the film, barrier properties against corrosive components, and processing resistance.

Forming into a two-piece can (seamless can) can be carried out by means known per se, for example, drawing-redrawing, drawing-redrawing-ironing, drawing-bending and redrawing, drawing-bending-drawing and ironing. And so on.

For example, deep drawing (drawing-redrawing)
According to the pre-draw cup formed from the coated metal plate,
It is held by an annular holding member inserted into the cup and a re-drawing die located thereunder. A redrawing punch is arranged coaxially with the holding member and the redrawing die so as to be able to enter and exit the holding member. The redrawing punch and the redrawing die are relatively moved so as to mesh with each other.

As a result, the side wall of the front drawing cup is bent perpendicularly inward from the outer peripheral surface of the annular holding member through the curvature corner thereof so that the annular bottom surface of the annular holding member and the upper surface of the redrawing die. Through the area defined by the above, it is bent almost vertically in the axial direction by the working corner of the redrawing die,
It can be formed into a deep drawing cup having a smaller diameter than the front drawing cup.

Further, the radius of curvature (Rd) of the working corner of the redrawing die is set to 1 to 2.9 of the metal plate thickness (tB).
By making the dimensions twice, especially 1.5 to 2.9 times, the thickness of the side wall can be effectively reduced by bending and pulling. In addition, the variation in the thickness between the lower portion and the upper portion of the side wall portion is eliminated, and uniform thickness reduction can be achieved over the whole. Generally, the side wall portion of the can body has a thinning rate (variation in thickness) of 5 to 45% (-5 to-) with respect to the blank thickness (tB).
45%), especially 5 to 40% (-5 to -40%).

In the case of a deep drawn can, the following formula (1) In the formula, D is the diameter of the sheared laminate material, and d is the punch diameter.
To 3.0, and preferably 1.5 to 5.0 in total.

Further, an ironing die is arranged at the rear of the redrawing or bending and redrawing, and the following formula (2) is applied to the side wall portion. In the formula, tB is the thickness of the base plate, and tW is the thickness of the side wall portion. The ironing rate RI defined by 5 to 70%, particularly 10 to 60%, may be reduced by ironing. it can.

In drawing or the like, various lubricants, for example, liquid paraffin, synthetic paraffin, edible oil, hydrogenated edible oil, palm oil, various natural waxes and polyethylene wax are applied to the coated metal plate or the cup to form. Good to do. The amount of the lubricant applied varies depending on the type of the lubricant, but it is generally preferably in the range of 0.1 to 10 mg / dm ² , particularly preferably in the range of 0.2 to 5 mg / dm ^2. It is performed by spraying the surface in a state.

In order to improve the drawability of the cup,
It is advantageous to set the temperature of the resin-coated drawing cup in advance in the range of not less than the glass transition point (Tg) of the coated resin, particularly not more than the thermal crystallization temperature, and mold the resin coating layer in a state in which plastic flow is facilitated. is there.

The inner side organic coated metal cup after molding is
After so-called trimming, in which the ear portion of the cup opening is cut, the printing process is performed. Prior to the trimming process, the cup after molding is removed from the glass transition point (T
g) or more and heating to a temperature lower than the melting point, so that the distortion of the coating resin can be alleviated. This operation is particularly effective in the case of a thermoplastic resin in order to increase the adhesion between the coating and the metal.

[Printing, painting and curing] In the present invention,
The printing of the ink can be performed by a known can-making printing method such as offset printing, planographic printing, gravure printing, and screen printing. On the other hand, the application of the UV-curable finish varnish is performed by the above-described means. The coating thickness of the finishing varnish is generally in the range of 3 to 10 μm.

As the ultraviolet light used for curing the finishing varnish or the like, a light having a wavelength of 220 to 420 nm, particularly 240 to 400 nm, including a near ultraviolet region, is generally used. As an ultraviolet light source, a metal halide lamp, a high-pressure mercury lamp, a low-pressure mercury lamp, or the like is used. Since the thickness of the finishing varnish layer and the like is extremely small, it is advantageous that the energy required for curing is considerably small, and an energy of 500 to 5000 joules / m ² is generally sufficient.

The printed seamless can after UV curing is not generally necessary, but may be heated as required to remove the distortion of the ink layer or the finished varnish layer. This heating can be performed by a hot air heating furnace, an infrared heating furnace, or the like.

In the present invention, the seamless can after printing, coating and curing is subjected to neck-in processing and flange processing to obtain a final can for cans. The neck-in processing can be performed in one or more stages by a known neck-in processing method, for example, a die method or a spin neck-in method. The opening end of the neck-in cup is engaged with a flanging die to perform flanging, thereby forming a flange for double-tightening the can end.

[0095]

The present invention will be further described with reference to the following examples, but the present invention is not limited to these examples. Manufacture of the used can, adjustment of ink and paint, and printing and painting were performed by the following methods.

[Manufacture of Seamless Can] (1) Thin-walled deep-drawn can with a base plate thickness of 0.18 mm and a temper degree of DR-9 (a surface treatment coating amount of a metal chromium amount of 120 mg / m ² and a chromium oxide amount of 15 mg / m ² ) on both sides of a 2 μm thick 20 μm
The axially stretched polyethylene phthalate / isophthalate copolymer film was simultaneously heat-bonded on both sides at the melting point of the film, and immediately cooled with water to obtain an organic-coated metal plate. After uniformly applying glamor wax to this organic coated metal plate,
A circular plate having a diameter of 160 mm was punched out, and a shallow drawn cup was formed according to a conventional method. The drawing ratio in this drawing step is 1.
59. Next, primary and secondary redrawing processes were performed to obtain a thinned deep drawing cup. The molding conditions in the redrawing step and various characteristics of the redrawn deep drawn cup are shown below. Primary redrawing ratio 1.23 Secondary redrawing ratio 1.24 Redrawing die action corner radius of curvature 0.30 mm Redrawing die holding corner radius of curvature 1.0 mm Cup diameter 66 mm Dip height 130 mm Sidewall thickness change rate: -40% After that, after performing doming molding according to a standard method, the deep drawing cup was heat-treated at 215 ° C for 1 minute to remove processing distortion of the film and volatilize the lubricant. Next, the open end was trimmed to obtain a resin-coated thinned deep drawn can having a height of 123 mm.

(2) Squeezing and ironing can Aluminum alloy material (3004-
H39), a disc having a diameter of 140 mm was punched out, a cup was formed at a drawing ratio of 1.6, then redrawn (drawing ratio of 1.3) and iron-formed (3 steps, total thinning rate 65%), and the inner diameter was reduced to 6%.
A 6 mm drawn ironing cup was formed. After the drawn and ironed cup is subjected to doming molding according to a conventional method, the height becomes 1
The opening end was trimmed to 23 mm, washed, treated, and dried according to a conventional method to obtain an aluminum squeezed and ironed can.

[Preparation of Ink and Paint] (1) UV Curable Ink A 3,4-Epoxycyclohexylmethyl-3,4-epoxycyclohexylcarboxylate 35 parts 3-Ethylhydroxymethyloxetane 5 parts Limonene oxide 5 parts Acrylic resin 15 parts Bisphenol A type epoxy resin 10 parts Dipropylene glycol monomethyl ether 5 parts Yellow pigment (yellow 83) 25 parts Dispersant 0.2 parts UVI-6990 (photo initiator, Union Carbide Corporation) 6 parts Acrylic resin, epoxy The resin is previously heated and dissolved in a cycloaliphatic epoxy resin or oxetane, pigments, initiators, etc. are added to this masterbatch, premixed, and then dispersed and mixed with three rolls to prepare the desired ink did.

(2) UV curable ink B bisphenol A glycidyl ether acrylate 30 parts 2-propenoic acid, 1,6-hexanediylbis [oxy (2-hydroxy-3,1-propanediyl)] ester 10 parts Nonylphenol EO Adduct acrylate 25 parts Acrylic resin 10 parts Yellow pigment (yellow 83) 25 parts Dispersant 0.2 parts Oligo [2-hydroxy-2-methyl-1- [4- (1-methylvinyl) phenyl] propane] 5 parts Acrylic The resin was previously dissolved by heating in an acrylate monomer / oligomer mixture, and a pigment, an initiator, and the like were added to the master batch, preliminarily mixed, and then dispersed and mixed with three rolls to prepare a target ink.

(3) UV-curable finishing varnish 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexylcarboxylate 70 parts Bis (3,4-epoxycyclohexyl) adipate 10 parts Limonenedioxide 7.5 parts Hydroxybutyl Vinyl ether 7.5 parts Bisphenol F type epoxy resin 5 parts EO modified silicone resin 0.5 parts UVI-6990 (photoinitiator, UCC) 4 parts Epoxy resin is previously heat-dissolved in alicyclic epoxy resin or vinyl ether. Then, other components were added to the master batch, and the mixture was stirred and mixed to prepare a desired finished varnish.

[Printing and Coating] Coating and printing were carried out at a rate of 1500 cans / min using a two-piece can printer schematically shown in FIG. When painting, use a diagonal anilox roll (number of lines 150 lines / inch, marking depth 41μ)
m) using about 1.2-1.4 laps. The applicator roll used was a butyl rubber type having a hardness of 50 degrees.

Example 1 Using a resin relief printing plate mainly composed of a solid portion, printing was performed on the thin-walled seamless can with the UV-curable ink A by a printer for a two-piece can, and then wet-on-wet. After coating the UV-curable finishing varnish and transporting the coating can for 4 seconds by a pin chain, while rotating the can, irradiate ultraviolet rays with a 200 W / cm output metal halide lamp to form a wet film of the ink and the finishing varnish. It was cured. When the surface roughness of this printing can was measured by Surfcom (SURFCOM 573A-3DF, Tokyo Seimitsu Co., Ltd.), the single part of the finished varnish was 0.19 μm and the wrap part was 0.23 μm.
A printed can with excellent appearance, in which the single part and the lap part of the finished varnish were not noticeable, was obtained.

Example 2 A printing can was produced in the same manner as in Example 1 except that the UV curable ink B was used. The surface roughness of this printing can was 0.20 μm in the single part of the finished varnish, and 0.2 in the lap part.
The printing can was 6 μm, and a printed can excellent in appearance with no noticeable step difference between the single portion and the lap portion of the finished varnish was obtained.

Example 3 Printing was performed on the drawn and ironed can using the UV-curable ink A by a printer for a two-piece can using a resin relief plate mainly composed of a base portion, and then wet-on-wet. After applying the UV-curable finishing varnish in the above manner, and transporting the coated can by a pin chain for 4 seconds, irradiating ultraviolet rays from a 200 W / cm output metal halide lamp while rotating the can to obtain a wet film of the ink and the finished varnish. Was cured. The surface roughness of this printing can was 0.15 μm in the single part of the finished varnish, and 0.22 μm in the wrap part.
Thus, a printed can having an excellent appearance in which the single part and the lap part of the finished varnish were not noticeable was obtained.

Comparative Example 1 A printing can was produced in the same manner as in Example 1, except that the time from coating to UV irradiation was 0.5 seconds. The surface roughness of this printing can was 0.33 μm in the single portion of the finished varnish and 0.68 μm in the wrap portion, and both the single portion and the wrap portion were rough and had a bad appearance.

Comparative Example 2 A printing can was produced in the same manner as in Example 1 except that the time from coating to UV irradiation was 2 seconds. The surface roughness of this printing can was 0.25 μm at the single part of the finished varnish, and 0.37 μm at the wrapping part.

Comparative Example 3 Printing was performed using the same can and ink as in Example 1 using a two-piece can printer, but the finished varnish coating unit was removed, and no UV irradiation was performed to obtain an undried printing can. Was. Then, this can was coated with a UV curable finishing varnish by a solid roll method instead of an anilox roll method so that the dry coating amount was 110 mg / can. The solid roll method is a coating method in which the coating amount is adjusted in a gap between two solid steel rolls, the paint on the steel roll is transferred to a rubber roll, and the paint on the rubber roll is applied to a can. The rubber roll used had a hardness of 30 degrees. Then, 4 seconds after coating, ultraviolet rays were irradiated from a 200 W / cm metal halide lamp to cure the wet film of the ink and the finish varnish. The surface roughness of this printing can is 0.12 μm in the single part of the finished varnish and the lap part is 0.29 μm. The roughness of the single part and the lap part of the finished varnish is 0.3 μm or less, but the lap part is Since the roughness of the single part was more than twice as large as that of the single part, the printed part had a poor appearance with a noticeable step difference between the single part and the lap part.

[0108]

According to the present invention, in a printing seamless can having a printing ink layer on its outer surface and a finishing varnish layer thereon, the finishing varnish layer is wrapped with a single coating portion and a small gap in the circumferential direction of the can body. Apply so that the application part is formed,
At this time, the finish varnish is applied to the outer surface of the seamless can by a combination of a grooved pumping roller and an applicator roller in which diagonal fine grooves are engraved, and ultraviolet curing is performed at least 3 seconds after the roller application, Finish varnish layer with a surface roughness of 0.3%
μm or less and less than twice the surface roughness of the single coated part. According to the present invention, this makes it possible to eliminate the disorder of the printed image or the decrease in gloss due to the roughness or the step in the wrap coating portion, and to enhance the aesthetic appearance and commercial value of the printing portion of the print seamless can.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view for explaining the occurrence of disturbance of a printed image in a seamless can.

FIG. 2 is a graph showing the surface roughness of a lap-applied portion obtained by applying a finish varnish layer to the outer surface of a seamless can and immediately curing it with an ultraviolet ray using a combination of a grooved pumping roller and an applicator roller.

FIG. 3 is a graph showing the surface roughness of a lap-applied portion obtained by applying a finish varnish layer to the outer surface of a seamless can using a combination of a grooved pumping roller and an applicator roller and curing the varnish after 4 seconds.

FIG. 4 is a side view for explaining a printing step and an ultraviolet curing step in the manufacturing method of the present invention.

FIG. 5 is a perspective view for explaining the arrangement of grooves of a grooved roller.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Shinya Otsuka 1950-49, Estuary City 4th Building 301, Rokuuracho, Kanazawa-ku, Yokohama-shi, Kanagawa Prefecture (72) Inventor Yasuhiro Yukawa 6-7 Shimoodanaka, Nakahara-ku, Kawasaki-shi, Kanagawa Prefecture −27

Claims (3)

[Claims] 1. A printing seamless can having an outer surface provided with a printing ink layer and a finishing varnish layer thereon, wherein the finishing varnish layer contains an ultraviolet curable resin, and the finishing varnish layer comprises a can body. It has a single coating portion and a lap coating portion at small intervals in the circumferential direction, and the surface roughness of the varnish layer wrap coating portion is controlled to 0.3 μm or less and less than twice the surface roughness of the single coating portion. Printed seamless cans characterized by being made. 2. A printing ink layer and a finish varnish layer containing an ultraviolet curable resin are applied to the outer surface of a seamless can, and the finish varnish layer is formed by a single application portion and a wrap application portion at a small interval in a circumferential direction of the can body. A method for producing a printed seamless can comprising applying and forming the finishing varnish layer or the printing ink layer with ultraviolet rays, wherein the finishing varnish is provided with a grooved pumping roller and an applicator roller engraved with diagonal fine grooves. And apply at least 3 after roller application
A method for producing a printed seamless can, comprising performing ultraviolet curing after a lapse of seconds. 3. The grooved roller has a depth of 30 to 60 μm.
3. The method according to claim 2, wherein m grooves are formed at a pitch of 100 to 180 grooves / inch.