JP2643800B2 - Method for coating metal surface with fluororesin film - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for coating a metal surface with a fluorine resin film containing a fluorine atom.

[0002]

2. Description of the Related Art In general, fluororesin films are excellent in properties such as corrosion resistance, stain resistance, adhesion resistance, heat resistance, and nonflammability. If possible, such characteristics of the film can be added to the excellent strength and workability of the stainless steel sheet, so that a laminated steel sheet having excellent functionality can be obtained. If there is such a laminated steel plate, it can be used for baking molds, food cooking utensils and food processing utensils used for baking bread, cake, confectionery, etc., or microwave oven inner plates, rice cooker inner pots and gas table top plates. Since it can be widely used for various cooking utensils, kitchen utensils such as range hood materials, etc., it has been desired to establish a technology for industrially producing such steel materials.

On the other hand, conventionally, JP-A-61-137534, JP-A-61-138567 and JP-B-63-11147 have been disclosed.
No. 59-16836, Japanese Patent Publication No. 59-16837, etc.
A material in which an Al-plated steel sheet is coated with a fluororesin, or JP-B-54-24434, JP-B-59-10304, JP-A-63
Development of a material in which a fluororesin film is laminated on a so-called Al or Al alloy material as seen in -126728, etc., and furthermore, thermosetting of a fluororesin film on a steel sheet, as seen in JP-A-63-168333, etc. Techniques for developing a method of laminating using a mold adhesive have already been proposed.

[0004]

As described above, a steel sheet obtained by laminating a fluororesin film has corrosion resistance,
Excellent in stain resistance, adhesion resistance, heat resistance, wear resistance and workability. However, fluororesin films are generally
Lamination with an adhesive is difficult because of low surface tension and strong non-adhesiveness. In particular, as in a tetrafluoroethylene-perfluoroalkylvinyl ether copolymer resin (PFA) and a tetrafluoroethylene-6-fluoropropylene copolymer resin (FEP), four or more fluorine atoms are contained in one molecular unit. As for the fluororesin film, an appropriate bonding method to a metal surface has not been developed so far, and the fact is that its practical use has been delayed.

[0005] In this regard, the present inventors first applied a mixture of a fluororesin and a heat-resistant resin to an aluminum-based steel sheet, a zinc alloy-based steel sheet, and a stainless steel sheet.
A film of the same type of resin is stuck thereon, and the roll is rolled down. When the roll is rolled down, a method of heating the interface between the film and the metal (steel plate) to a temperature just above the melting point of the film and fusing it with the underlying resin layer was found. No. 3-327744. More recently, in Japanese Patent Application No. 5-138770, a metal that has been subjected to a base treatment such as application of a primer, if necessary, is used.
Heat to a temperature of 50 to 450 ° C, and pre-press the fluororesin film on the surface by roll pressing or the like. Then, the interface temperature between the fluororesin film and its underlying metal surface is 280 ° C.
By reheating to the above temperature, a method of coating the fluororesin film on the metal surface was proposed,
Further improvements were desired. That is, the object of the present invention is to have excellent heat resistance, durability and adhesion,
In proposing a novel film coating method for manufacturing a fluororesin film-coated steel sheet excellent in various properties such as corrosion resistance, stain resistance, adhesion resistance, abrasion resistance, workability and material rigidity, In particular, it is an object of the present invention to establish a technique capable of continuously and pressure-bonding a fluororesin film containing four or more fluorine atoms in one molecular unit onto a metal surface with good adhesion.

[0006]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies for realizing the above object, and have found that the temperature of the metal surface and the temperature of the pressing roll surface can be controlled without being limited only to the temperature adjustment of the metal surface. By adjusting both, it was newly found that a good adhesive force between the fluororesin film and the metal can be stably obtained, and the present invention has been reached.

That is, the present invention provides a Zn-plated steel material which has been subjected to a phosphate treatment, a coating type chromate treatment, a primer coating containing a fluororesin and a heat-resistant resin, or a combination thereof, if necessary. -Al alloy plated steel, Zn-Fe alloy plated steel, Zn-Ni alloy plated steel, Al plated steel, Al-Si alloy plated steel, 55% Al-Zn
In a method of coating a metal film such as an alloy-plated steel material or a stainless steel material with a resin film made of a fluororesin containing 4 or more fluorine atoms in one molecule unit such as PFA or FEP, the resin film of the metal is used. The adherend surface is heated and adjusted in advance to a temperature 30 to 120 ° C. higher than the melting point of the fluororesin, and when the resin film is pressed against the metal surface with a pair of rolls, the roll surface on the film side is 100 to 21 from the melting point of the fluororesin
By adjusting the temperature to 0 ° C. lower, this is an advantageous method of coating the fluororesin film on the metal surface with high adhesion, and it is preferable that the surface of the metal film to which the resin film is applied be heated by induction heating.

[0008]

According to the present invention, first, a metal (hereinafter referred to as "steel plate") is used.
Immediately before the fluororesin film is superimposed on the surface and roll-rolled down, the surface of the steel sheet (in the case of primer treatment, the primer-treated steel sheet) of which the resin film is to be adhered is 30 to 120 degrees below the melting point of the fluororesin. It is necessary to adjust the heating to a temperature higher by ° C. For example, 340 to 430 ° C. in the case of a PFA resin film having a melting point of 310 ° C., a melting point of 2
In the case of a 70 ° C. FEP resin film, it is necessary to heat the film to 300 to 390 ° C. The temperature of the steel sheet or the like at this time in the above range is controlled by the type and thickness of the film, the surface temperature of the pressure roll, and the like. For example, a steel plate or primer-treated steel sheets were heated by Tsuban the tunnel furnace, when then out of the furnace as performing roll reduction of the film is necessary to heat only from the high temperature pre-temperature drop is there. Experience has shown that the temperature drop can be affected by factors such as sheet thickness, threading speed, the distance between the furnace and the reduction roll,
5050 ° C., and it is important to heat this much more. In this way, the surface temperature of the steel sheet or the like at the position immediately before the roll pressure is adjusted to a temperature 30 to 120 ° C. higher than the melting point of the fluororesin.

The reason why the surface temperature of the steel sheet is adjusted to the above range is that the temperature of the film-applied surface is lower than the melting point of the fluororesin by 30%.
If the temperature is not higher than ℃, the bonding surface of the fluororesin film does not melt, so that the bonding between the film and the steel plate surface or between the film and the primer becomes insufficient.
On the other hand, if the surface temperature exceeds 120 ° C. higher than the melting point of the fluororesin, the film itself may be melted and cut at the time of pressure bonding, and if a primer is used, the adhesion may be reduced due to thermal decomposition of the primer resin. Because it is done.

Although a general hot-air tunnel furnace may be used for heating the steel sheet, it is more preferable to use an electromagnetic induction heating furnace. The reason for this is that according to the electromagnetic induction heating, only the interface (adhesion surface) between the steel sheet and the film can be sufficiently heated, so that the adhesion of the film is improved. In addition, when a primer is used, the primer is heated from the inside (the steel plate side), so that the solvent remains less.

Next, the present invention provides a method of pressing a fluororesin film on a steel sheet surface which has been temperature-adjusted as described above, using a pair of rolls. It is necessary to adjust the temperature to 100 to 210 ° C lower. As the material of the pair of pressure rolls at this time, rubber or the like which is familiar with the steel sheet surface and has elasticity is suitably used. Therefore, rolls made of such a material are easily deteriorated by heat from the steel strip,
The temperature of the roll itself should not be raised to a high temperature such as 300 ° C or higher, and it is important to cool it appropriately so as to keep it at 210 ° C or lower.

The reason for adjusting the roll surface temperature on the film side during the pressure bonding to the above range is that when the roll surface temperature exceeds a temperature 100 ° C. lower than the melting point of the fluororesin, the cooling of the film surface is insufficient. This is because the film is in a molten state and there is a risk that the film is blown. On the other hand, when the temperature of the roll surface is lower than the temperature 210 ° C. lower than the melting point of the fluororesin, the film is rapidly cooled, and the film interface does not melt, resulting in poor adhesion.

The roll surface temperature on the side of the steel sheet which is not in direct contact with the film is not particularly limited, but is controlled in a range from a temperature 100 ° C. lower than the melting point of the fluororesin film to a temperature 50 ° C. higher than the melting point of the fluororesin film. Is preferred.

As described above, according to the present invention, the surface of the steel sheet to which the resin film is attached and the surface of the roll on the resin film side are both adjusted to a predetermined temperature range, and are usually subjected to pressure bonding at normal temperature. Since the resin film is subjected to pressure bonding in a state of being melted only at the interface with the steel sheet, a fluororesin film laminated steel sheet having excellent adhesion strength and the like can be continuously manufactured by roll pressing.

After the resin film is pressed against the steel sheet, a quenching treatment such as slow cooling by water cooling or water cooling is performed. However, cooling by any method affects the adhesive strength between the resin film and the steel sheet. Is negligible.

In the present invention, the base metals to be treated include the above-mentioned steel sheets, for example, galvanized steel, zinc-aluminum alloy-plated steel, zinc-iron alloy-plated steel, zinc-nickel alloy-plated steel, aluminum Plated steel, aluminum-silicon plated steel, 55% aluminum-zinc alloy plated steel, stainless steel, or the like is preferably used. When the metal is a steel plate, the metal preferably has a thickness of about 0.2 to 1.6 mm, but the type is not particularly limited and is selected according to the application. For example, for applications requiring high heat resistance, such as a gas stove top plate, an aluminum-plated steel plate or a stainless steel plate is suitable. Also, in order to obtain high film adhesion with a high melting point fluororesin film such as PFA, the metal surface must be heated to a high temperature of around 400 ° C. Dissolves and cannot be manufactured.

In the present invention, the fluororesin film to be coated on the above-mentioned metal material is one having particularly poor adhesion.
Fluororesin film containing 4 or more atoms of fluorine atoms in the molecule within the unit, for example, tetrafluoroethylene - perfluoro A
Alkyl vinyl ether copolymer resin (PFA) film and ethylene tetrafluoride-6-propylene copolymer resin (F
This is effective when a thermoplastic resin film such as EP) is used. Among them, PFA is most preferred. The thickness of the fluororesin film is not particularly limited, but is preferably 10 to 100 μm. In addition, these films are originally colorless and transparent, but those containing pigment powder for coloring or containing additives for imparting functionality, or those that have been treated in some way, can be used similarly. .

Further, in the present invention, before the heating adjustment of the metal surface, a base treatment of the metal is performed if necessary. This undercoating treatment is desirably performed by applying a primer. In addition, when the primer is not applied as the base treatment, a general method of performing pickling or electrolytic etching after polishing by shot blasting or wire brushing, or a coating type chromate treatment is performed as another pretreatment method. You may. In the case of a stainless steel plate, it is not just a primer treatment,
If the primer is treated after the coating type chromate treatment, the film adhesive strength, heat resistance and durability are remarkably improved.

As the primer for the base treatment of the base steel sheet, polytetrafluoroethylene (PTFE), tetrafluoroethylene-perfluoroalkylvinyl ether copolymer resin (PFA), tetrafluoroethylene-6-propylene fluoride copolymer resin (FEP), 4 tetrafluoroethylene - ethylene copolymer resin (ETFE), click Rollo trifluoroethylene, fluororesin powder selected and the like polyvinylidene fluoride, polyether sulfone (PES),
Polyphenylene sulfide (PPS), polyimide,
A water-based or organic solvent-based primer of a resin mixed with a heat-resistant resin selected from polyamideimide, epoxy resin, silicone resin, phenol resin and the like is preferably used.

[0020]

EXAMPLES Examples of the present invention will be described below in comparison with comparative examples. (Examples 1 to 4) PFA, FEP and PES were 1:
Fluororesin films were heat-sealed to various steel plates provided with a primer containing a 2: 1 mixed resin to obtain products. (Examples 5 to 6) Fluororesin films were heat-sealed to various steel sheets provided with a primer containing a mixed resin of FEP and PES at a ratio of 1: 2 to obtain products. (Examples 7 to 10) Fluororesin films were heat-sealed to various steel sheets subjected to a base treatment by a coating type chromate treatment to obtain products. Comparative Examples 1 to 6 Comparative Examples 1 to 6
Fluororesin films were heat-sealed to the various steel plates to obtain products. The respective manufacturing conditions are shown in Table 1 (FIG. 1).
reference). Table 2 shows the performance test results for the primary adhesion of each product.

[0021]

[Table 1]

[0022]

[Table 2]

In the above-described Examples 1 to 10 and Comparative Examples 1 to 6 under the conditions of thermocompression bonding of the fluororesin film, the pressure of the pressure roll on the steel sheet side is in the range of 150 to 250 ° C., and the linear pressure of the roll is
0.3 kg / cm. The processing conditions of the coating type chromate were chromium adhesion amount of 30 mg / m ² and drying at 150 ° C. for 30 seconds.

The test method and the judgment method of the adhesion in the above examples were performed under the following conditions. That is, JIS
The test was performed according to the Z type Ericksen test method of Z 6744. Two types of test specimens to be used in the Ericksen test were prepared by immersing them in boiling water for 1 hour or 2 hours, then drying them naturally for 30 minutes and not immersing them in boiling water. After extruding 6 mm with a machine, the cut edge of the extruded portion was lifted with a knife, grasped with tweezers and forcibly peeled off the film. The evaluation criteria are as shown in Table 3. For example, a case where the film could not be floated in all three types was set as an evaluation point 5.

[0025]

[Table 3]

As is evident from the results of the above tests, all of the fluororesin film-coated steel sheets produced according to the method of the present invention were superior in film adhesion to the fluororesin film-coated steel sheets according to Comparative Examples. . Moreover, according to the method of the present invention, it was possible to continuously produce a fluororesin film-coated steel sheet without causing the film to be melted when the resin film was pressed.

[0027]

As described above, according to the method of the present invention, a fluororesin film containing four or more fluorine atoms in one molecular unit can be firmly adhered to the metal surface. It is possible to continuously and inexpensively produce a fluororesin film-coated steel sheet having excellent properties.
Accordingly, the fluororesin film-coated steel sheet according to the present invention can be used as a material for cooking equipment, a material for kitchen equipment, an inner plate of a microwave oven, a top plate of a gas table, etc., as well as a material for electronic parts, a printed circuit board, or the like. It is possible to supply inexpensive and excellent materials suitable for a wide range of applications.

[Brief description of the drawings]

FIG. 1 is a view showing heat fusion conditions (based on a film melting point) in Examples and Comparative Examples.

Claims (3)

(57) [Claims] 1. A method of coating a metal film with a resin film made of a fluororesin containing 4 or more fluorine atoms in one molecular unit, wherein the surface of the metal film to which the resin film is adhered is determined in advance by a melting point of the fluororesin. While heating and adjusting to a temperature higher by 30 to 120 ° C. and pressing the resin film on the metal surface with a pair of rolls, the roll surface on the film side should be 100 to 210 ° C. higher than the melting point of the fluororesin.
A method of coating a metal surface with a fluororesin film, which is adjusted to a low temperature. 2. The method for coating a metal surface with a fluororesin film according to claim 1, wherein the heating of the surface on which the metal resin film is applied is performed by induction heating. 3. A fluorine resin containing in one molecule unit of 4 or more atoms of fluorine atoms, tetrafluoroethylene - is perfluoroalkyl vinyl ether copolymer resin or a tetrafluoroethylene-hexafluoropropylene copolymer resin A method for coating a metal surface with the fluororesin film according to claim 1.