JP2002226780A - High brilliance coating material for laminated can and method for manufacturing laminated can - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high brilliance coating material for laminated cans which has a feeling of brilliance and opacifying properties and excellent adhesion to the neck-processed portion after retorting, and a method for manufacturing a laminated can. SOLUTION: The high brilliance coating material for laminated cans is obtained by dispersing metallic thin foil strips into a varnish containing a thermoplastic resin, and the method for manufacturing a laminated can comprises printing or coating the high brilliance coating material for laminated cans on the surface of a film to form a surface layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to metal cans such as beverage cans, cans, aerosol cans and art cans for soft drinks, coffee, tea, tea, beer, etc.
The present invention relates to a high-brightness coating agent for laminated cans used for a laminated metal plate having rust resistance.

[0002]

2. Description of the Related Art As a method for producing metal cans, gravure printing on polyester film is used because of its advantages such as high productivity, excellent flavor, environmental hormonal measures, and a clear printing effect.
A laminated metal plate method in which a gravure coating or the like is applied and the resultant is bonded to a metal plate with an adhesive has been in practical use for several years. Conventionally, in order to impart high brightness to the printed matter, a so-called metallic coating agent in which a pigment such as aluminum paste, aluminum powder, or pearl (mica) is added to the coating agent has been used. However, in order to develop a high brightness feeling, the pigment having a relatively large particle size is used. On the contrary, the concealing property is reduced, and at the same time, peeling of the neck processed portion and blistering after retort treatment are liable to occur.

[0003]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a high-brightness for a laminate can which gives a high brightness without impairing the concealing property and which does not cause peeling of a neck processed portion and blistering after retort processing. An object of the present invention is to provide a coating agent and a method for producing a laminate can using the coating agent.

[0004]

Means for Solving the Problems As a result of intensive studies, the present inventors have found that a high-brightness coating agent containing a metal thin film strip solves the above-mentioned problems, and has reached the present invention. That is, the present invention provides a high-brightness coating agent for laminate cans, characterized in that a metal thin film strip is dispersed in a varnish containing a thermoplastic resin. The present invention also relates to a method for producing a laminate can having a glittering surface layer, comprising printing or applying a high-brightness coating agent for a laminate can, in which metal thin film strips are dispersed in a varnish containing a thermoplastic resin, on the film surface. The present invention provides a method for producing a laminate can, characterized in that a surface layer is formed by the method.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The high-brightness coating agent for a laminate can used in the present invention contains a metal thin film strip and a thermoplastic resin. Normally, metal powder is used for the metallic coating agent, but when a metal thin film is used, the metal thin film is oriented in a direction parallel to the surface of the workpiece when the coating agent is applied. Thus, a high-luminance mirror-like metallic luster that cannot be obtained with conventional metal powders can be obtained.

(1) Metal thin film strip The metal of the metal thin film strip is aluminum, gold, silver,
Copper, brass, titanium, chromium, nickel, nickel chrome, stainless steel and the like can be used. As a method of forming a metal into a thin film, in the case of a metal having a low melting point such as aluminum, aluminum, gold, silver, copper or the like having a malleable foil, in the case of a metal having a high melting point and having no malleability, , Sputtering and the like. The thickness of the metal thin film is preferably from 0.01 to 0.1 μm, more preferably from 0.03 to 0.08 μm. The size in the plane direction of the metal thin film strip dispersed in the coating agent is
5 to 25 μm is preferred, and more preferably 10 to 15 μm.
μm. When the size is less than 5 μm, the luminance of the coating film becomes insufficient, and when it exceeds 25 μm, the metal thin film strips are less likely to be oriented, so that the luminance is reduced. Further, when the high-brightness coating agent is printed or applied by a gravure method or a screen printing method, it causes clogging of the plate.

Hereinafter, a method for producing a metal thin film strip will be described by taking a vapor deposition method as an example. As the support film on which the metal is deposited, a polyolefin film, a polyester film, or the like can be used. First, after a release layer is provided on a support film by coating, a metal is deposited on the release layer to a predetermined thickness. A top coat layer is applied to the surface of the deposited film to prevent oxidation. The same coating agent can be used for the release layer and the top coat layer.

[0008] The resin used for the release layer or the top coat layer is not particularly limited. Specific examples include cellulose derivatives, acrylic resins, vinyl resins, polyamides, polyesters, EVA resins, chlorinated polypropylenes, chlorinated EVA resins, and petroleum resins. Examples of the solvent include aromatic hydrocarbons such as toluene and xylene, aliphatic or alicyclic hydrocarbons such as n-hexane and cyclohexane, esters such as ethyl acetate and propyl acetate, methanol, ethanol, isopropyl alcohol and the like. Alcohols, ketones such as acetone and methyl ethyl ketone, and alkylene glycol monoalkyl ethers such as ethylene glycol monoethyl ether and propylene glycol monomethyl ether can be used.

The above-mentioned metal-deposited film is immersed in a solvent for dissolving the release layer and the top coat layer and stirred, and the metal-deposited film is peeled off from the support film. Filter to about 150 μm, filter and dry. The solvent is not particularly limited except that it dissolves the resin used for the release layer or the top coat layer.

When a metal thin film is formed by sputtering, a metal thin film strip can be formed in the same manner as described above. When a metal foil is used, it may be pulverized to a predetermined size with a stirrer as it is in a solvent.

The metal thin film strip is preferably subjected to a surface treatment in order to enhance dispersibility in a high-brightness coating agent for a laminate can. Examples of the surface treatment agent include organic fatty acids such as stearic acid, oleic acid, and palmitic acid, methylsilyl isocyanate, nitrocellulose, cellulose acetate propionate, cellulose acetate butyrate, and cellulose derivatives such as ethylcellulose. To adsorb on the surface of the metal thin film strip.

(2) Thermoplastic resin varnish As the thermoplastic resin, polyurethane resin, polyester resin, polyurethane urea resin, vinyl chloride / vinyl alcohol copolymer resin, vinyl acetate / vinyl alcohol copolymer resin, vinyl chloride / vinyl acetate / vinyl resin Examples thereof include an alcohol copolymer resin, a vinyl chloride / vinyl acetate copolymer resin, an acrylic resin, a polyamide resin, a nitrified cotton, an epoxy resin, an acetal resin, and a butyral resin. These resins do not need to be one kind and can be used by mixing.
The resin constituting the thermoplastic resin varnish preferably contains a resin having active hydrogen and a blocked isocyanate compound.

As the resin having active hydrogen, polyurethane resin, polyester resin, polyurethane urea resin,
Vinyl chloride / vinyl alcohol copolymer resin, vinyl acetate / vinyl alcohol copolymer resin, vinyl chloride / vinyl acetate / vinyl alcohol copolymer resin, vinyl chloride / maleic acid copolymer resin, vinyl acetate / maleic acid copolymer resin,
Examples thereof include a vinyl chloride / vinyl acetate / maleic acid copolymer resin, an acrylic resin, a polyamide resin, a nitrified cotton, an epoxy resin, an acetal resin, and a butyral resin. These resins do not need to be one kind and can be used by mixing.

As the blocked isocyanate compound,
Use isocyanurate-type polyisocyanate, violet-type polyisocyanate, and adduct-type polyisocyanate in which terminal isocyanate groups are masked with a blocking agent. Preferred as organic diisocyanate as a raw material of the blocked isocyanate compound,
Examples include 1,6-hexamethylene diisocyanate, isophorone diisocyanate, 4,4'-diphenylmethane diisocyanate, xylylene diisocyanate, tolylene diisocyanate, naphthylene diisocyanate, and mixtures thereof. Also, as a blocking agent,
Malonate diester, acetoacetate, acetylacetone and the like as active methylene compounds, acetoxime and ketoxime (methylethylketoxime, butanone oxime) and the like as oxime compounds, phenol and cresol as phenol compounds, ε-caprolactam and the like as lactam compounds, Examples of the imidazole compound include 2-methylimidazole. The blocking agent does not necessarily need to be one kind, and can be used by mixing.

If necessary, zinc octylate for the purpose of accelerating the dissociation of the blocking agent of the blocked isocyanate compound;
An organic metal catalyst such as dioctyltin diacetate (DOTDA), dibutyltin dilaurate (DBTDL), or dibutyltin diacetate (DBTDA) can be used in combination.

As long as high brightness and physical properties are not impaired, defoaming, settling prevention, blocking prevention,
Various additives for the purpose of preventing static charge and the like can be used in combination.

The high-brightness coating agent for a laminate can of the present invention is prepared by mixing the above-mentioned raw materials for mixing, since the metal thin-film flakes to be compounded in order to exhibit a metallic luster are suitably about 5 to 25 μm in size. Is preferred. For the purpose of improving dispersibility, it is preferable that the above-mentioned metal thin film strip is surface-treated.

Examples of a plastic film that can be used for a laminate can include a polyester resin film, polypropylene, nylon, and a polyethylene resin film. A polyester resin film is particularly preferably used. Film thickness is usually 10-20
About μm is preferably used. For a two-piece can,
Since the film is laminated by being wound around an undrawn can body, the film thickness is usually thicker than in the case of a three-piece can.

The coating agent for a laminate can of the present invention is printed or applied to these films. As a printing method, a method such as gravure printing, flexographic printing, or screen printing is used. As a coating method, a gravure coater, gravure reverse coater, flexi coater, blanket coater, roll coater, knife coater, air knife coater, kiss touch coater, comma coater and the like can be used. According to the present invention, it is possible to manufacture a laminated can having a high-brightness surface comparable to metal deposition or the like by a high-speed and inexpensive method called printing or coating. As the adhesive, any known adhesive may be used. For example, an adhesive having a white pigment such as titanium using a thermoplastic polyester resin or polyurethane resin as a binder is used.

The metal plates used include galvanized steel plates, chromium-plated steel plates, tin-plated steel plates, nickel-plated steel plates, aluminum-plated steel plates, various other alloy-plated steel plates,
It is also possible to use stainless steel, aluminum plate, copper plate, titanium plate, or, if necessary, those subjected to phosphoric acid treatment, chromate treatment, organic chromate treatment, cobalt composite oxide film treatment, or the like.

In the case of a three-piece can, the printed or coated film is laminated on a metal plate and then processed by a conventional process. In the case of a two-piece can, the film is cut into a can size. The laminated film is laminated while being wound around a can body having an unprocessed neck. After that, the neck is drawn. The laminate can needs to withstand a retort process at about 125 ° C. for about 30 minutes as needed. The high-brightness coating agent for a laminate can of the present invention,
Even when severe processing such as three-step and four-step neck processing, barrel can processing, and the like, which were difficult in the past, exfoliation and blistering of the processed part after retort processing can be eliminated, and high design with excellent design properties can be achieved. This enables the production of a laminated can with high brightness.

[0022]

EXAMPLES The present invention will be described below in detail with reference to examples, but the present invention is not limited to these examples. In the examples, parts are parts by weight.

Example 1 Nitrocellulose (HIG)
Aluminum-deposited film strip slurry 3 surface-treated in 7)
0 parts (10% slurry part), polyurethane urea resin (Barnock L4-079, manufactured by Dainippon Ink and Chemicals) 20
Parts, 25 parts of methyl ethyl ketone, 17.5 parts of toluene,
7.5 parts of isopropanol was blended and stirred and mixed to produce a high-brightness coating agent (A) for a laminate can. After adjusting this ink for 17 seconds (Zahn cup NO3) with a predetermined diluting solvent, it was printed on a polyester film having a thickness of 12 μm by a printing machine equipped with a gravure plate having a depth of 35 μm and dried to obtain a printed film. Obtained. Next, an electron beam and a thermosetting white adhesive were applied to the printing surface in an amount of 1
Coating to 1 g / m ² (dry), after drying 7 at room temperature
Aged for days. Next, the coated film and the tin-plated steel sheet are thermocompressed using a hot roll at 180 ° C., irradiated with an electron beam of 30 KGy at an acceleration voltage of 165 KV and a current value of 3 mA, and further baked at 215 ° C. for 90 seconds. To produce a laminated metal plate.

Example 2 High Brightness Coating Agent (A)
A blocked isocyanate compound in which the terminal isocyanate group of isocyanurate-type polyisocyanate using hexamethylene diisocyanate as a raw material is blocked with methyl ketoxime [blocked isocyanate compound (C), effective NCO% = 6.5%] 2 per 100 parts Was added and mixed with stirring to prepare a high-brightness coating agent for a laminate can. Hereinafter, a laminated metal plate was prepared under the same conditions as in Example 1.

Example 3 30 parts (10% slurry part) of aluminum-deposited film strip slurry surface-treated with CAP (“CAP482-05” manufactured by Eastman Chemical Company), polyurethane urea resin (Burnock L4-07)
9, Dainippon Ink and Chemicals, Inc.), 25 parts of methyl ethyl ketone, 17.5 parts of toluene, and 7.5 parts of isopropanol were mixed and stirred and mixed to prepare a high-brightness coating agent (B) for a laminate can. Example 1 below
Under the same conditions as above, a laminated metal plate was prepared.

Example 4 A block isocyanate compound obtained by blocking terminal isocyanate groups of isocyanurate type polyisocyanate using hexamethylene diisocyanate as a raw material with methyl ethyl ketoxime with respect to 100 parts of a high-brightness coating agent (B) for a laminate can [ Blocked isocyanate compound (C), effective NCO%
= 6.5%], and stirred and mixed to prepare a high-brightness coating agent for laminate cans. Hereinafter, a laminated metal plate was prepared under the same conditions as in Example 1.

Comparative Example 1 20 parts of aluminum paste having an average particle diameter of 10 μm (AL content 70%, toluene / mineral spirits 30%), polyurethane urea resin (Bernock L4-079, manufactured by Dainippon Ink and Chemicals, Inc.)
30 parts, methyl ethyl ketone 25 parts, toluene 17.5
Parts and 7.5 parts of isopropanol were blended and mixed by stirring to prepare a comparative coating agent. Hereinafter, a laminated metal plate was prepared under the same conditions as in Example 1.

Comparative Example 2 20 parts of aluminum paste having an average particle diameter of 30 microns (AL content 70%, toluene / mineral spirits 30%), and polyurethane urea resin (Bernock L4-079, manufactured by Dainippon Chemical) 30
Parts, 25 parts of methyl ethyl ketone, 17.5 parts of toluene,
7.5 parts of isopropanol was blended and stirred and mixed to prepare a comparative coating agent. Hereinafter, a laminated metal plate was prepared under the same conditions as in Example 1.

The performance of the laminated metal plates obtained in Examples 1 to 4 and Comparative Examples 1 and 2 was evaluated.
It was shown to. The conditions for each performance evaluation are as follows.

[Appearance of laminated metal plate] The prepared laminated metal plate was subjected to a retort treatment at 125 ° C for 30 minutes.
The appearance (luminance, concealing property, etc.) was evaluated on a five-point scale with a magnifying glass or visually. Very good (◎), good (○), slightly poor (△), bad (×), very bad (xx).

[Neck workability] The prepared laminated metal plate was drawn down to a diameter of 25 mm, a height of 8 mm and a height of 12 mm using a deep drawing Erichsen machine, and subjected to a retort treatment at 125 ° C for 30 minutes, and the appearance (blister of blister). (E.g., occurrence of wrinkles, film wrinkles, etc.) were evaluated on a five-point scale with a magnifying glass or visually.
“8mm height drawing” is roughly equivalent to 3 steps neck processing, “1 height”
“0 mm drawing” corresponds to approximately four-step neck processing. Very good (◎), good (○), slightly poor (△), poor (×), very poor (xx).

[0032]

[Table 1]

From the above experimental results, it can be seen that the high-brightness coating agent for a laminated can of the present invention has improved adhesion to the film and the adhesive layer after baking the can, and particularly after the coating agent is laminated and subjected to severe neck processing. It can be seen that the retort resistance of the is improved.

[0034]

The use of the high-brightness coating agent for laminated cans of the present invention makes it possible to achieve three-stage and four-stage coatings which have been difficult in the past.
In the case of severe processing such as step neck processing and barrel can processing, peeling of the processed portion and occurrence of blisters after retort processing can be eliminated, thereby enabling production of a laminated can excellent in design.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C09C 3/10 C09D 5/00 Z C09D 5/00 7/12 7/12 11/10 11/10 175 / 04 175/04 B65D 1/00 BF term (reference) 3E033 AA06 BA07 BA13 BA17 BA19 BA21 BA24 BB08 EA10 GA02 3E061 AA16 AB13 AC01 AD04 BA01 BA02 DB08 4J037 AA04 AA05 CC02 CC11 CC12 CC15 CC16 CC24 CC27 DD10 EE02 EE04 FE04 CD041 CE021 CE071 CF021 CG001 DA011 DB001 DD001 DG101 DG111 DG151 DG161 DG171 DG191 DG301 DH001 GA03 GA06 GA12 HA066 KA08 KA15 KA20 MA07 MA10 NA01 NA12 NA19 PB04 PC08 4J039 AB02 AD05 AD06 AD07 AD08 AD04 AE01 FA03 AE01 GA09 GA10

Claims (4)

[Claims] 1. A high-brightness coating agent for laminated cans, characterized in that a thin metal film strip is dispersed in a varnish containing a thermoplastic resin. 2. The high-brightness coating agent for a laminated can according to claim 1, wherein the metal thin film strip is surface-treated with a cellulose derivative. 3. A resin constituting a thermoplastic resin varnish,
The high-brightness coating agent for a laminated can according to claim 1 or 2, comprising a resin having active hydrogen and a blocked isocyanate compound. 4. A method for producing a laminate can having a brilliant surface layer, comprising printing or coating a high-brightness coating agent for a laminate can, in which a thin metal thin film is dispersed in a varnish containing a thermoplastic resin, on the film surface. Forming a surface layer by performing the method.