JP4203407B2 - LAMINATE STEEL STEEL EXCELLENT IN RESISTANCE IN CANNING - Google Patents

Description

  The present invention relates to a laminated steel sheet used for applications in which the outer surface after canning is a laminated surface and a method for producing the same.

In recent years, steel plates laminated with thermoplastic resin such as polyethylene (PE), polypropylene (PP), and polyethylene terephthalate (PET) on electric steel plate, TFS, and other surface-treated steel plates (instead of coated steel plates) Hereinafter referred to as a laminated steel plate).
As a method for producing a laminated steel sheet, a pre-heated steel sheet pressed by a pair of rolls, a thermal laminating method in which a pre-formed thermoplastic resin film is bonded to a surface-treated steel sheet (hereinafter referred to as a steel sheet) by thermocompression bonding, and There is a T-die laminating method in which a thermoplastic resin film having a temperature higher than that of a T-die is supplied near the interface of one roll and adhered to a steel plate.

  Regarding this T-die laminating method, for example, in JP-A-2-241737, a rolling roll is pressed against a preheated steel sheet wound around a winding roll, and an extruder is disposed in the vicinity of the interface between the pressing roll and the steel sheet. A method of manufacturing a laminated steel sheet is disclosed in which a thermoplastic resin film having a temperature higher than that of a T-die is flowed down and laminated on a surface-treated steel sheet and then cooled, and JP-A-3-158235 discloses. Then, a high-temperature thermoplastic resin film wider than the width of the steel sheet is allowed to flow down, and the entire width of the steel sheet is covered with a uniform film thickness at the center in the width direction of the resin film. Insert the film between the preheated steel sheet and the winding roll so that the film is covered with the non-uniform film thickness of the part, and the operation will not be disabled by winding the resin around the winding roll To do In both cases, a method for obtaining a laminated steel sheet having a uniform resin film thickness over the entire width of the steel sheet is disclosed, and further, JP-A-10-16132 discloses that a film is inserted between a preheated steel sheet and a high-temperature thermoplastic resin film. Then, after laminating, before or after cooling the laminated steel sheet, a method of forming a non-laminated portion by peeling the film together with the thermoplastic resin film is disclosed.

As for the composition of the resin layer, for example, Japanese Patent No. 3343423 discloses a resin-coated metal plate for cans having a resin film made of a saturated polyester resin and an ionomer resin, as disclosed in Japanese Patent No. 2677512. The publication discloses a resin-coated metal plate for cans composed of two layers of a crystalline saturated polyester resin layer and a resin layer made of a saturated polyester resin and an ionomer resin.
However, although the conventional PET laminated steel sheet is difficult to be scratched by devising the material of the resin film in this way, it is often manufactured by a can-making machine that also serves as a non-laminated steel sheet, and the resin film on the surface of the laminated steel sheet There was a problem that wrinkles were likely to enter compared to the metal surface and painted surface of the non-laminated steel sheet.
Therefore, conventionally, the laminated surface is coated with oil to such an extent that no wrinkles enter, and depending on the product, a degreasing step is required thereafter.
In addition, as a prior art which prescribed | regulated the surface roughness of the resin layer, Unexamined-Japanese-Patent No. 2000-272048 and Unexamined-Japanese-Patent No. 2000-190423 have disclosed the steel plate which has a matt surface, and the steel plate excellent in impact resistance. However, there was no one that defined the roughness from the viewpoint of the resistance to wrinkling at the time of can making, which is the subject of the present invention.
JP-A-2-241737 Japanese Patent Laid-Open No. 3-158235 Japanese Patent No. 3343423 Japanese Patent No. 2677512 JP 2000-272048 A JP 2000-190423 A

The present invention solves the problems of the prior art as described above, and is a single-sided laminated steel plate used for forming processing of a can bottom of a three-piece can whose outer surface after canning is a laminated surface. Providing a laminated steel sheet and a method for producing the same that are excellent in rust resistance at the time of can and can reduce costs by omitting an oiling process and a degreasing process that are conventionally required or by reducing oiling. Let it be an issue.

As a result of intensive studies to solve the above-mentioned problems, the present invention provides a surface roughness of the PET laminate surface in which the surface PET resin is a crystalline saturated polyester resin in order to improve wrinkle resistance at the time of making the laminate surface. By adjusting the degree, it has excellent scratch resistance when making the laminate surface used for the outer surface after canning, reducing the cost by omitting the oiling process and degreasing process that were conventionally required or by reducing oiling The present invention provides a laminated steel sheet and a method for producing the laminated steel sheet, the gist of which is as follows.
(1) A single-sided laminated steel sheet used for forming a bottom of a three-piece can whose outer surface after canning is a laminated surface,
Forming a PET resin film having a resin layer (A) comprising a mixture of a saturated polyester resin and an ionomer resin on the steel sheet side, and having a crystalline saturated polyester resin layer (B) on the outer surface side; and
A laminated steel sheet having excellent wrinkle resistance during can making, wherein the surface roughness of the laminate surface of the PET resin film is 0.14 to 0.20 μmRa.
(2) A method for producing the laminated steel sheet according to (1) by a T-die laminating method,
Production of a laminated steel sheet having excellent scratch resistance at the time of can-making, characterized in that the pressure roll for pressing the resin film flowing down from the T-die onto the steel sheet surface is a rubber roll having a surface roughness of 1.0 to 1.2 μmRa Method.
(3) The method for producing a laminated steel sheet having excellent scratch resistance during can making according to (2), wherein the rubber roll is a silicon roll.

According to the present invention, the outer surface after canning is adjusted by adjusting the surface roughness of the PET laminate surface using a crystalline saturated polyester resin as the surface PET resin in order to improve the wrinkle resistance during canning of the laminate surface. Providing a laminated steel sheet and its manufacturing method that have excellent resistance to wrinkling when making a laminated surface for cans and can reduce the cost by omitting the oiling process and degreasing process or reducing the oiling required in the past It has a remarkable effect which is useful in the industry.

The best mode for carrying out the present invention will be described in detail with reference to FIGS.
FIG. 1 is a view showing a T-die laminating apparatus used in the present invention.
In FIG. 1, 1 is a steel plate, 2 is a resin, 2 'is a laminate surface, 3 is a T die, 4 is a winding roll, and 5 is a pressure roll.
The heated and melted resin 2 flows down from the T-die 3 and is sandwiched between the winding roll 4 and the pressure-bonding roll 5 and is pressure-bonded to the surface of the steel plate 1 to form a resin film having a thickness of 10 to 30 μm on the surface of the steel plate. Form.

FIG. 2 is a view showing a resin configuration of the laminated steel sheet of the present invention.
As shown in FIG. 2, the laminated steel sheet of the present invention has a resin layer (A) made of a mixture of a saturated polyester resin and an ionomer resin on one side of the steel sheet 1, and a crystalline saturated polyester resin layer ( A PET resin film having B) is formed.
Since the resin layer (A) made of a mixture of a saturated polyester resin and an ionomer resin has good adhesion to the steel plate, it is arranged on the steel plate side.
Moreover, since the crystalline saturated polyester resin layer (B) arrange | positioned at the outer surface side is a hard resin layer, wrinkles can be reduced.

Furthermore, the laminated steel sheet of the present invention is characterized in that the surface roughness on the laminate surface of the PET resin film is 0.14 μmRa or more.
As a result of various experiments on the relationship between the roughness of the laminated surface and the scratch resistance, the present inventors have found that the scratch resistance is good when the surface roughness is 0.14 μmRa or more. .
The reason for this is that if the surface roughness of the laminate surface is small, the contact area with the mold for can manufacturing becomes large, and it is difficult to slip, so the laminate surface is likely to be scratched by the mold. When the roughness is large, the contact area with the can mold is small and slippery, so the laminate surface is considered to be difficult to be wrinkled by the mold.
If the surface roughness of the laminate surface exceeds 0.20 μmRa, the glossiness of the laminate surface is lost. Therefore, when the appearance is important, the surface roughness of the laminate surface is preferably 0.14 to 0.20 μmRa.

FIG. 3 is a cross-sectional view of a pressure roll used in the method for producing a laminated steel sheet of the present invention.
In the present invention, it is preferable to use a rubber roll having a surface roughness of 1.0 μmRa or more of the pressure roll for pressure bonding the resin film.
By setting the surface roughness of the pressure roll to 1.0 μmRa or more, the surface roughness transferred to the laminate surface can be set to 0.14 μmRa or more.
Further, when the surface roughness of the pressure roll exceeds 1.2 μmRa, the polishing marks of the roll are transferred to the laminate surface. Therefore, when importance is attached to the appearance, the surface roughness of the rubber roll is preferably 1.0 to 1.2 μmRa. .
Further, the pressure-bonding roll used in the present invention has releasability with respect to PET resin and has sufficient heat resistance. As in the comparative example shown on the left side of FIG. 3, a Teflon tube (Teflon tube) However, Teflon tubes have relatively poor durability and need to be replaced in a short time.
On the other hand, as shown in the example of the present invention shown on the right side of FIG. 3, by using a rubber roll made of silicon rubber instead of the Teflon tube, the operation time until replacement can be extended.

FIG. 4 is a diagram showing the relationship between the surface roughness of the pressure roll and the roughness of the laminate surface in the laminated steel sheet of the present invention.
In FIG. 4, the horizontal axis represents the surface roughness (μmRa) of the pressure-bonding roll, and the vertical axis represents the lamellar surface roughness (μmRa).
As shown in FIG. 4, the larger the surface roughness of the pressure roll, the greater the roughness of the laminate surface. When the surface roughness of the pressure roll is 1.0 (μmRa) or more, the roughness of the laminate surface is appropriate. The range can be 0.14 (μm Ra) or more.
In addition, when the surface roughness of the pressure roll exceeds 1.2 (μmRa), the roll polishing marks are transferred to the laminate surface. Therefore, the preferable range of the surface roughness of the pressure roll is 1.0 to 1.2 (μmRa). .

Table 1 shows examples in which the can bottom of the three-piece can shown in FIG.
When the roughness of the laminate surface was changed sequentially in the range of 0.06 to 0.24 (μmRa), wrinkles at the time of canning occurred when it was less than 0.14 (μmRa), but at 0.14 (μmRa) or more, wrinkles at the time of canning were Did not occur.
Further, when the roughness of the laminate surface was less than 0.20 (μmRa), gloss was observed, but when the roughness was more than 0.20 (μmRa), no appearance gloss was recognized.

It is a figure which shows the T-die laminating apparatus used for this invention. It is a figure which shows the resin structure of the laminated steel plate of this invention. It is sectional drawing of the crimping | compression-bonding roll used for the manufacturing method of the laminated steel plate of this invention. It is a figure which shows the relationship between the surface roughness of the crimping | compression-bonding roll in the laminated steel plate of this invention, and the roughness of a lamination surface. It is a figure which shows the test piece used for the Example in the laminated steel plate of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Steel plate 2 Resin 2 'Laminating surface 3 T die 4 Winding roll 5 Crimp roll

Claims (3)

A single-sided laminated steel sheet used for forming a bottom of a three-piece can where the outer surface after making the can is a laminated surface,
Forming a PET resin film having a resin layer (A) comprising a mixture of a saturated polyester resin and an ionomer resin on the steel sheet side, and having a crystalline saturated polyester resin layer (B) on the outer surface side; and
A laminated steel sheet having excellent wrinkle resistance during can making, wherein the surface roughness of the laminate surface of the PET resin film is 0.14 to 0.20 μmRa. A method for producing the laminated steel sheet according to claim 1 by a T-die lamination method,
Production of a laminated steel sheet having excellent scratch resistance at the time of can-making, characterized in that the pressure roll for pressing the resin film flowing down from the T-die onto the steel sheet surface is a rubber roll having a surface roughness of 1.0 to 1.2 μmRa Method.   The method for producing a laminated steel sheet having excellent scratch resistance during can making according to claim 2, wherein the rubber roll is a silicon roll.

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