JP2583472B2 - Thermoplastic resin film striped coated metal plate and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal plate coated with a thermoplastic resin film in the form of a horizontal stripe (hereinafter referred to as a thermoplastic resin film-stripe-coated metal plate), which is mainly used for the body of a welding can and the like. Regarding the manufacturing method,
More specifically, the present invention relates to a metal plate coated with a thermoplastic resin film having excellent weldability and corrosion resistance applied to food cans, beverage cans, art cans, 18 l cans and the like, and a method for producing the same.

[0002]

2. Description of the Related Art Conventionally, a film laminated steel strip for a three-piece can (Japanese Patent Application No. 3-236954) has been proposed as a thermoplastic resin-coated steel sheet for producing a welded can body. This is a film having a certain non-laminated portion extending in the length direction of the steel strip, and having a thermoplastic resin film coating extending in the length direction of the steel strip with a width corresponding to the height of the can. It is a laminated steel strip. In the present invention, in order to laminate the steel strip,
Either a method of bonding a long film slit in advance to the height of the can or a method of slitting while supplying a wide film is used. The non-laminated portion existing between the films is provided with a predetermined interval in advance so as to be a welded portion at the time of cylinder production (hereinafter, referred to as a vertical striped laminated steel strip).

[0003]

However, when the vertical striped laminated steel strip is applied to a welding can, there is a problem that a flanging crack is generated in a flanging step after manufacturing the welding can body. That is, when cutting a blank sheet for a welding can from a vertical striped laminated steel strip and manufacturing a welding can body, since the rolling direction and the height direction of the can are the same, the occurrence of flanging cracks from the welded portion may occur. Frequent. Further, when the can body is formed with the rolling direction as an axis, there is another problem that a so-called diamond can is easily formed because the elongation of the plate is not uniform in plastic working.

[0004]

The present invention has been studied to solve the above-mentioned problems. As a result, the thermoplastic resin film-stripe-coated metal plate of the present invention is uncoated with a thermoplastic resin film in a direction perpendicular to the longitudinal direction. And the dimension between adjacent uncoated portions is substantially the same as the dimension in the circumferential direction of the can. Further, the invention is characterized in that the metal plate is coated with a thermoplastic resin film cut at a predetermined interval so as to form a non-coated portion of the thermoplastic resin film in a direction perpendicular to the longitudinal direction of the metal plate.

[0005]

The horizontal striped coated metal plate of the present invention will be described with reference to the drawings. In FIG. 1, reference numeral 1 denotes a coated metal plate;
Is a thermoplastic resin film, and 3 is a non-coated portion of the thermoplastic resin film (hereinafter referred to as an uncoated portion). The uncovered portion 3 has a certain width and extends in a direction substantially perpendicular to the longitudinal direction of the metal plate (that is, extends in a direction substantially perpendicular to the rolling direction). The reason for extending in the perpendicular direction is to reduce the occurrence of flanging cracks in the flanging process. That is, when the rolling direction of the metal plate coincides with the height direction of the can, flanging cracks are likely to occur at the upper and lower ends of the can body in the flanging step of attaching the lid to the top and bottom of the can. For this reason, it is preferable that the can body blanking be performed so that the rolling direction and the can height direction are perpendicular to each other. Therefore, the uncovered portion serving as a welded joint is extended in a direction perpendicular to the rolling direction. Can provide a material having excellent can moldability. The reason that the distance between the non-coated portions corresponds to the circumferential direction of the can is that when the non-coated portions are aligned with each other and the can body is welded and joined, the distance between the non-coated portions becomes the can perimeter. . These correspondences will be described below with reference to the drawings. The width A of the thermoplastic resin film is determined depending on the type of the can of the horizontal striped coated metal plate. That is, since the width A of the thermoplastic resin film in FIGS. 2 and 3 substantially matches the circumference C of the can after molding, it is used for a large can such as an 18 l can or for a small beverage can such as a juice can. It depends on whether it is used. For example, when used as an 18 l can, as shown by the broken line in FIG. 2, the user determines the can height size B and cuts it into a blank sheet for a welded can body. The can height B is substantially equal to the height of the can after the can is formed. The blank sheet cut in this manner is processed and formed so that the non-covered portions 3 are overlapped and welded to each other with a predetermined width (referred to as a wrap margin), and are welded by applying a predetermined electrode pressing force. The wrap margin is usually 0.3 to 3 mm. The width of the non-covered portion 3 is determined in consideration of the wrap margin and the type of can. In a large can such as an 18 l can, the width D of the uncoated portion is set to about 3 to 8 mm. In a small can, the width of the uncoated portion is set smaller than in the case of the large can, and is about 1 to 4 mm. The welded portion and the uncovered portion 3 on the inner and outer surfaces of the can after welding are repaired with paint, a thermoplastic resin, a thermosetting resin, or the like. The paint or the like used for repair may be liquid or solid, but it is necessary to select a paint having good adhesion to the thermoplastic resin film. Further, a tape-shaped thermoplastic resin film can be repaired by heat fusion.
When a horizontal striped coated metal plate is used for an adhesive can, the uncoated portion 3 can be coated and then bonded using an adhesive such as nylon by a conventional method. Metal plates are non-ferrous metal plates such as cold rolled steel plates and aluminum plates,
A surface-treated steel plate or the like can also be used. As the surface-treated steel sheet, one or two or more of tin plating, thin tin plating, chromium plating, zinc plating, nickel plating, electrolytic chromic acid treatment, chromic acid treatment, and the like can be used. Usually, in these steel sheets, a chromate treatment layer is formed on the outermost layer in order to impart corrosion resistance and paint adhesion, but this chromate treatment layer is not always necessary. These materials generally have poor weldability due to heating in the painting and baking steps, but the effect of heating is particularly large for electrolytic chromic acid-treated steel sheets. It is considered that the reason for this is that an oxide film having poor electric conductivity grows on the surface layer by repeating heating at a temperature around 200 ° C. for about 10 minutes several times in the baking step. Therefore, when a thermoplastic resin film is used as the coating layer instead of the coating film, heating for a short time during coating is sufficient, so that the weldability is remarkably improved. Further, when the coating step is performed in a gas atmosphere containing no oxygen, further improvement in weldability can be expected.

Next, thermoplastic resin films include: (1) olefin resin films such as polyethylene, polypropylene, ethylene-propylene copolymer, ethylene-vinyl acetate copolymer, ethylene-acryl ester copolymer, and ionomer; 2) Polyester such as polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, ethylene terephthalate / isophthalate copolymer, etc. (3) Polyamide such as nylon 6, nylon 6.6, nylon 11, nylon 12, etc. (4) polyvinyl chloride, And polyvinylidene chloride. These thermoplastic resin films have different characteristics in terms of heat resistance, corrosion resistance, and adhesiveness to a metal plate, but can be properly used according to the contents of the food can. Further, when the adhesion of these thermoplastic resin films to the metal plate is not sufficient, for example, epoxy-based adhesive, phenol-based adhesive, amide-based adhesive, urethane-based adhesive, acid-modified olefin resin-based adhesive , A copolyamide-based adhesive, a copolyester-based adhesive, a blend thereof, and the like.

In general, the thickness of the thermoplastic resin film is preferably in the range of 3 to 50 μm. When the thickness is 3 μm or less, the coating workability is remarkably reduced, and pinholes are easily generated, so that sufficient working corrosion resistance cannot be obtained. On the other hand, when it exceeds 50 μm, it is not economical as compared with a paint widely used in the field of can making.

Next, a method for producing a metal plate in which the thermoplastic resin film of the present invention is coated in a stripe shape will be described with reference to the drawings. FIG. 4 is an embodiment showing a manufacturing apparatus for manufacturing a metal plate in which the thermoplastic resin film of the present invention is coated in a horizontal stripe shape. In FIG. 3, 50 and 50 are film pay-off reels, 51 and 51 are film running shearing devices, 52 and 52 are belt conveyor devices, and 53 and 53.
Is a belt having a number of small diameter holes, 54 and 54 are suction conveyor belt devices, 55 and 55 are rolls with holes, 56 and
56 is a coating roll. First, the roll-shaped thermoplastic resin film 20 rewound from the film pay-off reel 50 is sheared at a predetermined interval by the film running shearing device 51, and is sucked upward one by one by the suction conveyor belt device 54.

The peripheral speed of the film payoff reel is
By making the peripheral speed of the suction conveyor belt device 54 slower, a gap is formed between the cut films. This gap will be used as it is as the gap between the coating films of the coated metal plate (D). However, this gap may be slightly enlarged due to heat shrinkage at the time of coating the film, so it is necessary to confirm it by an experiment in advance. Since the roll 55 with holes has many small-diameter holes in the roll shell, the zone a is maintained at a negative pressure, the zone b is maintained at a positive pressure, and the zone c is maintained at an atmospheric pressure, and is supplied from the suction conveyor belt device 54. The cut film can be reliably transferred to the covering roll 56. Also, the voltage applying device 5 is
When an electrostatic charge is given at 7, 57, the cut film can be received more stably from the suction conveyor belt device 54. The cut films lined with a certain gap on the coating roll 56 are heat-coated on the metal plate 1,
A metal plate coated with a thermoplastic resin film in the form of a horizontal stripe in which an uncoated portion having a width of 8 mm extends in a direction perpendicular to the longitudinal direction of the metal plate is manufactured. When the film is coated on both sides of the metal plate in the form of a horizontal stripe, alignment of the double-sided film is important. For example, the use of an edge position controller or the like facilitates control. That is, the light amount detection sensors 58, 58 for detecting the amount of reflected light of the covering roll 56 are installed above the covering roll 56, and the position information of the cutting film is obtained by the change of the light amount, so that the thermoplastic resin film coated on the metal plate is obtained. 2, the displacement of the coating position can be known. By feeding this information back to one of the suction conveyor belt devices 54, both surfaces can be aligned. In addition, the coated metal plate of the present invention can be manufactured by a method other than the above method. For example, a metal plate may be coated with a film cut in advance to a predetermined size while keeping a certain interval.

Heating methods required for coating include a heater roll heat transfer method, an induction heating method, a resistance heating method, and a hot air transfer method. From the viewpoint of equipment costs and simplification of equipment, the heater roll heat transfer method is used. Is preferred. As for the cooling method after coating, it is preferable to cool the film to 100 ° C. or less within 5 seconds after coating from the viewpoint of preventing changes in physical properties of the thermoplastic resin film and oxidation of the metal plate surface. The metal plate coated with the thermoplastic resin film is wound into a coil shape after cooling, but the surface may be coated with oil to impart lubricity. It is necessary that the amount of oil applied does not hinder weldability. The coil-shaped metal plate coated with a thermoplastic resin film for a welding can body is cut as it is or in a sheet shape.

[0011]

【Example】

(Example 1) On both sides of a cold-rolled steel sheet having a thickness of 0.21 mm,
891 m2 of a trace tin-coated chromium-plated steel sheet coated with 100 mg / m2 of metallic chromium, 150 mg / m2 of tin and 10 mg / m2 of chromium hydrated oxide as chromium
The reel around which the biaxially stretched copolymerized polyester film having a width of m was cut was cut at an interval of 204 mm, and a steel strip having a width of 889 mm was coated on both sides of the steel strip at an interval of 4 mm and covered in a horizontal stripe shape. Polyester film thickness 20 μm Melting point of polyester film 230 ° C. Heating method of steel sheet Heater roll method Steel sheet temperature just before coating 220 ° C. Cooling method after coating Rapid cooling The obtained coated metal sheet is cooled to a predetermined size of a blank sheet for a welding can (207 × 125 mm: Same in the following examples)
Cut into pieces.

(Embodiment 2) An electrolytic chromic acid-treated steel sheet coated with 80 mg / m 2 of chromium metal and 5 mg / m 2 of chromium hydrated oxide as chromium on both sides of a cold-rolled steel sheet having a thickness of 0.21 mm, While cutting the biaxially stretched PET film having a shrinkage ratio of 2% in the width direction of the film when heated at 150 ° C. in a horizontal stripe shape with a razor blade immediately before the covering roll, the steel plate is continuously cut under the following conditions. Was coated on both sides. PET film thickness 15 μm Melting point of PET film 260 ° C Heating method of steel sheet Heater roll method Steel sheet temperature just before coating 275 ° C Cooling method after coating Rapid cooling The obtained coated metal sheet is cut into specified dimensions of a blank sheet for welding cans did.

(Example 3) A cold rolled steel sheet having a thickness of 0.21 mm is made of 80 mg / m 2 of chromium metal and 5 mg of chromium.
/ M2 of chromium hydrated oxide coated electrolytic chromic acid-treated steel sheet, a biaxially stretched maleic acid-modified polypropylene film having a shrinkage ratio of 1% in the width direction of the film when heated at 140 ° C. was placed just before the coating roll. , And continuously coated on both sides of the steel sheet under the following conditions while cutting in a horizontal stripe shape with a leather blade. Thickness of acid-modified polypropylene film 25 μm Melting point of acid-modified polypropylene film 150 ° C Heating method of steel sheet High frequency induction heating method Steel sheet temperature immediately before coating 170 ° C Cooling method after coating Rapid cooling The obtained coated metal sheet is used as a blank sheet for welding cans. Of the specified size.

The properties of the horizontal stripe-coated metal plates obtained in Examples 1, 2 and 3 were evaluated by the following methods, and the results are shown in Table 1. A 207 × 125 mm blank sheet for a welding can body was seam-welded to a diameter of 52.3 mm to form a cylindrical can body. This can body was evaluated by a spin flanger device 60 shown in FIG. That is, the welding can body is fixed to the lower end of the apparatus, and while rotating the spin holder 62 having five spins 61, the can body 63 is forcibly forced from the upper part of the apparatus.
Inserted inside. The can body end 64 has a shoulder radius of 2.03 mm.
The diameter is forcibly expanded by the spin. When the spin holder 62 is further lowered, flanging cracks occur at the can body end 64. In the evaluation, the degree of occurrence of flanging cracks was visually determined while keeping the holder descending distance constant. As a result, in the case where the blank sheet of the present invention was welded, no flanging crack GSA was found. In comparison, the blank sheet of the conventional product had one or several flanging cracks visually.

[0016]

According to the present invention, flanging cracks do not occur at all in the flanging process after the production of a welded can body, and a normal can body end is formed. A fastening is obtained. Further, the elongation of the plate became uniform in the can body forming step, and a so-called diamond can was not formed at all.

[Brief description of the drawings]

FIG. 1 is a schematic explanatory view of a metal plate in which a thermoplastic resin film is covered in a horizontal stripe shape.

FIG. 2 is a schematic explanatory view when a blank sheet for forming a can is taken from a coated metal plate.

FIG. 3 is an explanatory view for forming a can body.

FIG. 4 is an embodiment showing a manufacturing apparatus for manufacturing a coated metal plate.

FIG. 5 is a schematic explanatory view of a spin flanger.

[Explanation of symbols]

 Reference Signs List 1 coated metal plate 2 thermoplastic resin film 3 uncoated part

Claims (2)

(57) [Claims] 1. A striped thermoplastic resin film in which a non-coated portion of a thermoplastic resin film is formed in a direction perpendicular to a longitudinal direction of a metal plate, and a dimension between adjacent non-coated portions is substantially the same as a dimension in a circumferential direction of a can. Coated metal plate. 2. A method of coating a metal plate with a thermoplastic resin film cut at predetermined intervals so as to form a non-coated portion of the thermoplastic resin film in a direction perpendicular to a longitudinal direction of the metal plate. A method for producing a striped coated metal sheet of a plastic film.