JPH05124648A - Three-piece can with multi-layer structure organic film on can external surface - Google Patents

Abstract

PURPOSE:To make a continuous operation of painting and printing processes possible, and at the same time, provide a three-piece can with an excellent printing appearance by constituting the film of the three-piece can, of a specified structure. CONSTITUTION:The can external surface shall have a thermosetting adhesive layer/printing ink layer to show a trade mark design/polyester film layer with stretching orientational property/lubricant film layer, from the steel plate side, or a thermosetting organic coating layer/thermosetting adhesive layer/printing ink layer to show a trade mark design/polyester film layer with stretching orientational property/organic film with a multi-layer structure, consisting of a lubricant film layer, from the steel plate side. By having such a structure, a continuous operation of painting and printing processes for a three-piece can is made possible. That is, a biaxially oriented polyester film, etc., is made to be a base, and a trade mark design to show the content is printed at a photogravure printing line, and the film is laminated on the surface of a steel plate at a high speed coil coating line to achieve the continuous operation.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a can container, and more particularly to a three-piece can in which a can body is manufactured by bonding or welding. At least the outer surface of the can body has a printing ink layer having a trademark design and a stretch orientation. The present invention relates to a three-piece can having a multi-layered organic film in which an organic film such as a polyester film layer is laminated.

[0002]

2. Description of the Related Art Looking at a can container from the viewpoint of the can manufacturing process,
There are two major categories. One is a can with the can bottom and can body integrated, and is usually wrapped in a canopy. Usually called a two-piece can, a typical can is a D1 can (Draw and can) made by squeezing and ironing. lroned
And a DrD can (Draw) that is made by drawing.
and Redrown can). The other is a body and canopy wrapped around the body, usually called three-piece cans. Typical cans are solder cans, adhesive cans, and welded cans. Cans are the mainstream.

As materials for three-piece cans, tin-based materials in which a steel plate is subjected to tin plating and chromate treatment, nickel-based materials in which a steel plate is subjected to nickel plating and chromate treatment, and steel sheets including metallic chromium and hydrated chromium oxide are used. Tin-free steel-based materials with layer coatings and others are used. In most of these materials, the inner surface of the can is coated from the viewpoint of content retention (corrosion resistance), and the outer surface of the can is printed with a trademark design for indicating the content.

Such inner surface coating and outer surface printing are carried out by cutting the above-mentioned material for a three-piece can into a cutting plate, and then, on a cutting plate coating line, an inner surface coating (first time), an outer surface printing base coating (second time), It is manufactured by three-pass printing of outer surface printing (third time). For applications that require a high degree of corrosion resistance, it may be necessary to coat the inner surface twice, and if the outer surface printing is multicolor printing of 5 colors or more, it may be necessary to print twice. As a result, the inner and outer surfaces may be painted or printed by four-pass or five-pass. Then, it is necessary to heat the cut plate in the baking oven for each passing of the plate.

In order to rationalize such a coating and printing process,
It is expected that the so-called coil coating method will consistently and continuously perform internal coating, white coating for external printing, and even external printing, but it is difficult to achieve printing accuracy when using a metal base. , Has not been put to practical use. Then, the can-body joint part of the steel plate coated and printed by such a number of cutting plate line passing is left uncoated in the case of, for example, a welded can, and after being cut into a can size. It is rolled into a cylindrical shape and welded into a three-piece can body.

The technique of laminating a film on a steel plate has been around for a long time, and has been conventionally studied in the field of can containers. For example, as seen in JP-A-62-227642 and JP-A-58-82717, the prior art is mainly used for two-piece cans such as squeezed cans and squeezed and ironed cans, 18 liter cans and can lids. There is no technology called a three-piece can in which a film on which a product design is printed is laminated on the outer surface of the can as in the present invention.

[0007]

As described above, in the current three-piece can field, in order to reduce the can manufacturing cost,
Efforts have been made to make the cut plate coating and printing processes continuous, but only the coating was continuous, but the continuous printing was not achieved. On the other hand, there is a demand for the appearance of cans that are cheaper than conventional three-piece cans, are more vivid, have a deep print appearance, and have a high product image and excellent design.

[0008] The three-piece can coating printing process is (1)
Poor productivity, (2) long work-in-progress, (3) requiring a lot of manpower, (4) difficult to improve the appearance of the finished print, (5) difficult to use ultra-thin materials, etc. It had many problems and was a cause of reducing the competitiveness of the three-piece can. The present invention drastically changes this complicated coating and printing process to enable coating and printing in a coil shape continuously by one pass, and to achieve a more vivid and deep printing appearance. An object is to provide a can having a high product image and excellent design.

[0009]

Means for Solving the Problems That is, the gist of the present invention is to provide a thermosetting adhesive layer / printing ink layer for displaying a trademark design / stretch orientation from the steel sheet side on the surface of the steel sheet which is the outer surface of the can. Polyester film layer / lubricating film layer having, or thermosetting organic coating layer / thermosetting adhesive layer / printing ink layer showing trademark design / polyester film layer having stretch orientation / lubricity from the steel plate side A three-piece can having a multi-layer organic coating film layer.

The present invention will be described in detail below. The present invention is to laminate a film on which a trademark design is printed in advance on the surface of a steel plate to obtain a three-piece can manufactured from the steel plate. The reason why the can body of the present invention requires the above-mentioned multilayer structure is as follows. First, the polyester film layer having stretch orientation is used as a carrier for the printing ink layer and the top coat layer. That is, since it is difficult to perform direct continuous printing on a steel plate, continuous printing is performed on a film, and by continuously laminating the printed film on the steel plate surface, continuous printing on the steel plate is indirectly possible. Is.

The printing ink layer is for displaying canned contents, brands, etc., and for displaying a trademark design. The primary purpose of the lubricating film layer is to prevent surface scratches in a high-speed can manufacturing line, but it is also necessary to secure the appearance such as image clarity. The thermosetting adhesive layer is a pre-printed film laminated with sufficient adhesive strength over the entire can size, and has sufficient adhesive strength to prevent peeling during can manufacturing processing or heat sterilization processing after filling the contents. Is to secure.

The thermosetting organic coating layer is used to secure the clarity of the print design, and a paint containing a white pigment is often used, but a paint containing no pigment is used to improve the adhesion. May be used. The present invention also includes the case where this thermosetting organic coating layer is not required. next,
Each layer of the multilayer organic coating layer applied to the can of the present invention will be described.

[0013] As for the body of a three-piece can, at present, both the bonding and welding methods are the mainstream. However, in the case of a welding can by the welding method, since the welding is performed without painting, repair painting is performed from the viewpoint of corrosion resistance after welding. Is required. This repair coating is also in the direction of baking for a short time from the viewpoint of productivity, and the maximum attainable temperature may locally reach 280 ° C. The influence of such heat causes local melting or a change in crystal state when the melting point of the film is low, which causes a deterioration in designability of the trademark design. Further, after the body is made, the canopy is fastened, the contents are filled, and the ground is fastened. However, except when the contents are carbonated beverages, usually high temperature filling or heat sterilization treatment (retort treatment) in a temperature range of 80 to 130 ° C. ) Is done. At this time, if the crystal structure of the resin film changes,
This leads to the deterioration of the appearance described above.

In the case of a polyester resin film, a polyester having a high melting point of about 260 ° C. can be obtained by selecting an alcohol component and an acid component, and by imparting stretch orientation, heat resistance in a can making process and a filling process. Since it can also be secured, it has wide applicability and is preferable. Even a polyester film having a structure having no orientation is not practical because it has a crystal structure having processability or corrosion resistance in a can making process, a filling process, or the like.

Next, the thickness of the film applied to the present invention will be described. In the present invention, the film thickness is 20 μm
The following applies. If it is less than 5 μm, if the film is scratched during the can making process, it may cause rusting of the film.
It is not preferable because it causes deterioration of appearance. On the other hand, the upper limit is limited in terms of rust resistance and appearance. In order to secure the rust resistance of the outer surface of the can, it is advantageous to have a thick film,
If it is too thick, a step will be formed between the film laminated portion and the non-laminated portion (in the vicinity of the welded portion), which may cause deterioration in touch feeling or damage to the film, thus causing a problem. Therefore, the thickness of the laminated film is 8 to 2
It can be said that the range of 0 μm is preferable.

As the adhesive used in the present invention, it is necessary to select an adhesive that does not cause wrinkles or film peeling due to the above-mentioned baking or retort treatment of the repair coating. It is necessary to use a thermosetting adhesive. The thickness of the adhesive layer is 0.5 to 4 μm. If it is less than 0.5 μm, the adhesive strength is not sufficiently secured, and if it exceeds 4 μm, the effect is saturated. The range is preferably 1 to 3 μm.

The lubrication film on the outermost surface is formed from the viewpoint of preventing scratches on the film in the can manufacturing process and from the viewpoint of plate passing, and is a film having a static friction coefficient of 0.2 or less, such as an acrylic film.
A polyester-based paint containing Si-based fine particles or an organic lubricant is applied. Thickness is 0.5-4μ
m. If it is less than 0.5 μm, the friction coefficient does not decrease and no effect is observed. If it exceeds 4 μm, the friction coefficient does not decrease further and the effect is saturated.

The ink layer applied to the present invention is for printing a trademark design, and an ink containing urethane resin as a main binder and having excellent heat resistance and retort resistance is used. From the viewpoint of enhancing the appearance of printing, which is an important object of the present invention, it is judged that gravure printing is preferable.
It goes without saying that the thickness of the ink layer varies widely depending on the trademark design and cannot be basically limited.

In the present invention, there are cases where a thermosetting organic coating layer is required between the steel sheet and the adhesive, and where it is not required. When a thermosetting organic coating layer is not required, a four-layer coating of thermosetting adhesive layer / printing ink layer displaying a trademark design / polyester film layer having stretch orientation / lubricant coating layer from the steel plate side Become. On the other hand, when the thermosetting organic coating layer is required, the composition is thermosetting organic coating layer / thermosetting adhesive layer / printing ink layer indicating the trademark design / stretch orientation from the steel sheet side. It becomes a five-layer film of polyester film layer / lubricating film layer.

The thermosetting organic coating layer referred to in the present invention means an epoxy-based paint, an acrylic-based paint, a polyester-based paint,
This refers to resin coatings such as phenolic paints and is a heat-curable type. As described above, a white pigment such as titanium oxide may be added to the thermosetting organic coating layer in order to secure the sharpness of printing. Pigment addition amount is 1 to 30% by weight
The range of is selected. The coating layer containing no white pigment may have a thickness of 1 to 3 μm, and the coating layer containing a white pigment may have a thickness of 5 μm.
15 μm.

The steel sheets used in the present invention are Al, Cr,
A surface-treated steel plate plated with Ni, Sn, or the like and having a plate thickness of 0.10 to 0.25 mm is often used. Specifically, after the tin plating coating weight 0.5 to 3.0 g / m ^2, tin-plated steel sheet subjected to chemical conversion treatment, Ni deposition amount 0.3 to 2.0 g / m ²
Nickel-plated steel sheet after nickel plating, which has been subjected to chemical conversion treatment, and Sn and Ni adhesion amounts of 0.5 to 2.0, respectively.
g / m ^2, after plating the 0.1 to 0.5 g / m ² Ni, in the order of Sn, chemical Sn / Ni plated steel sheet subjected to the treatment, a metal chromium coating weight 50~120mg / m ^2, chrome oxide coating weight 5-2
0 mg / m ² normal TFS (Tin Free Stage)
l) Chromium / chromate treated steel plate, etc.

The can of the present invention can be formed by a dry laminating method in which a film on which a lubricious film has been applied and a trademark design has been printed is laminated on a steel plate to which an adhesive has been applied. After printing, there is a method such as applying an adhesive to the ink layer surface and laminating a dried film on a heated steel plate.The steel plate having the multi-layer organic film thus obtained is used for ordinary welding cans, adhesive cans, etc. Can be made by means of a three-piece can body.

The effects of the present invention will be specifically shown in the following examples.

[0024]

【Example】

Example 1 A thermosetting polyester coating containing a silicone lubricant was added to a 10 μm biaxially stretched polyester film in an amount of 2 μm.
After coating and drying, a trademark design of four colors was gravure-printed on the opposite surface, and a urethane adhesive of 1.5 μm was coated on the printing ink and dried. The total thickness of the printed film produced was 16 μm. On the other hand, S with a thickness of 0.16 mm
Sn / N with n deposition of 1.0 g / m ² and Ni deposition of 0.3 g / m ²
After i-plating, 5 μm of an epoxy ester-based paint containing a white pigment was applied to a chromate-treated steel plate, and when the temperature reached 200 ° C. by induction heating, the above-mentioned printed film was thermocompression bonded (Sample 1).

A printed film with the same specifications as above is
It was laminated at 200 ° C. on a steel plate having an epoxy ester coating film containing a white pigment of 3 μm (Sample 2). In any of the prototyped laminated steel sheets, the crystal orientation of the biaxially stretched polyester film remained without any problem.
It had the structure intended by the present invention. From the organic laminated steel sheets having the multilayer structure of Sample 1 and Sample 2 thus obtained, the multilayer organic film surface was made to be the outer surface of the can.
We manufacture a 50 ml juice can body by welding, repair painting the welded part, and reach the maximum temperature (local temperature of the repair painting part) 250
It was dried at ° C.

The can bodies obtained from Sample 1 and Sample 2 were both good in gloss and free from color unevenness, and the image clarity was better than that of the existing three-piece cans. The can body thus obtained was necked-in, and the canopy was further wound on one end, then the contents were filled, and the lid was closed and sealed, and then retorted at 125 ° C for 30 minutes. When the film was examined for changes in appearance and adhesion, no change was observed and it had a good appearance.

Example 2 A thermosetting polyester coating prepared by adding a silicone lubricant to a 9 μm biaxially oriented polyester film was used.
After the coating of μm and drying, a trademark design of 6 colors was gravure-printed on the opposite surface, and a 2.0 μm urethane adhesive was applied and dried on the printing ink. The total thickness of the produced printing film was 15.5 μm. The same plated steel sheet as in Example 1 was coated with an epoxy paint containing no white pigment at 6 μm.
After coating and drying, the above-mentioned film was laminated thereon at 195 ° C. (Sample 3).

The same film was directly laminated on the same plated steel sheet as in Example 1 at 195 ° C. without applying an undercoat (Sample 4). As a result of analyzing the polyester resin film structures of the sample 3 and sample 4 that were prototyped, the crystal orientation of the biaxially stretched polyester film remained without any problem, and it had the structure intended by the present invention.

From the multi-layered organic laminated steel sheets of Samples 3 and 4 thus obtained, a 250 ml juice can barrel was manufactured by welding so that the surface of the multi-layered coating was the outer surface of the can, and the welded portion was repair-painted. It was dried at a maximum reaching temperature of 230 ° C. The obtained can bodies were both glossy and free of color unevenness, and the image clarity was better than that of the existing three-piece cans. After necked-in processing, and further winding the canopy on one end, filling the contents, winding the lid and sealing, and then performing retort treatment at 125 ° C for 30 minutes. There was no problem in adhesion.

Example 3 A steel plate having a thickness of 0.15 mm was plated with Ni having an adhesion amount of 0.6 g / m ² and then a chromate-treated steel plate was coated with 8 μm of an epoxy ester-based paint containing a white pigment, heated and dried. After 8
Cooled to 0 ° C.

On the other hand, a 12 μm biaxially stretched polyester film was coated with 1 μm of a thermosetting polyester paint containing a silicone lubricant, dried, and then 1.8 μm was applied to the film surface on which the trademark design of 5 colors was gravure printed.
A urethane-based adhesive of m 2 was applied as a solvent, and the solvent was blown off to laminate the adhesive on the surface of the steel sheet (Sample 5).

From the multi-layered organic coating steel sheet of Sample 5 thus obtained, 2 so that the surface of the multi-layered organic coating was the outer surface of the can.
A 50 ml juice can body was manufactured by welding, the welded part was repaired and painted, and dried at a maximum attainable temperature of 250 ° C. The can body obtained from Sample 5 had good gloss, no color unevenness, and more excellent image clarity than the existing three-piece cans. After necked-in processing, and further wrapping the canopy on one end, fill the contents, wrap the hood and seal, then
The film appearance and adhesion after retort treatment at 25 ° C. for 30 minutes were also good.

[0033]

The invention guarantees many advantages. That is, by using a special multi-layer structure, continuous coating printing using coil products can be performed at high speed with a wide width, and it is possible to secure productivity more than double that of the cutting plate coating line. it can. Since it is not necessary to pass the line through many times, the work-in-process period can be shortened. The use of coil products also has the advantage that even if the material plate is extremely thin, it does not cause such a great handling problem. It is possible to solve the problems in the conventional painting and printing process of a steel plate for a three-piece can, such as labor saving by omitting the process.

Further, by adopting the gravure printing, it is possible to print with a clearer image and deeper than the current external printing cans, and it is possible to supply three-piece cans that are compatible with the diversification and high quality of consumers. Yes, it has great social significance.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Ochigi Yachichi 20-1 Shintomi, Futtsu-shi, Chiba Central Research Division, Nippon Steel Corporation (72) Inventor Tomohiko Hayashi 20-1 Shintomi, Futtsu-shi, Chiba Japan Central Research Division, Steel Works Co., Ltd.

Claims (3)

[Claims] 1. A thermosetting adhesive layer / printing ink layer for displaying a trademark design / polyester film layer having stretch orientation / lubricant coating layer, or a steel sheet side on the steel sheet surface corresponding to the outer surface of a can. Can having a multi-layered organic coating of thermosetting organic coating layer / thermosetting adhesive layer / printing ink layer for displaying trademark design / polyester film layer having stretch orientation / lubricant coating layer Three-piece can with a multi-layered organic coating on the outer surface. 2. A three-piece can having a multi-layered organic coating on the outer surface of the can, wherein the thermosetting organic coating layer contains a white pigment. 3. The total film thickness of the thermosetting adhesive layer / printing ink layer displaying a trademark design / polyester film layer having stretch orientation / lubricant film layer is 20 μm or less. A three-piece can having a multi-layered organic coating on the outer surface of the can.