JPH06226913A - Laminated metallic plate and its production - Google Patents

Abstract

PURPOSE:To improve brightness of reflectivity of a laminated metallic plate in which films are laminated in the upper and lower two layers. CONSTITUTION:Surface roughness of the coated surface of a base metallic plate is regulated to Ra <=1mum and Rmax <=3mum. Softening point or melting point (TA) of resin of the upper layer film and softening point or melting point (TB) of resin of the lower layer film satisfy the relation of TA>TB. The laminate is reheated and treated at the temperature T for satisfying TB<T<TA in a state under nonpressure after lamination and the brightness of reflectivity is enhanced. Thereby the laminated metallic plate high in brightness of reflectivity is obtained at high product yield without necessitating drastic improvement of a manufacturing facility.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laminated metal plate in which two or more kinds of thermoplastic resin film layers of different types are laminated on a metal plate and a method for producing the same. More particularly, the present invention relates to a laminated metal plate having excellent image clarity and suitable for use in the fields of home electric appliances and building materials, and a manufacturing method thereof with high yield.

[0002]

2. Description of the Related Art Laminated metal plates in which two or more multi-layer resin film layers are laminated on a metal plate for various purposes have been conventionally known. For example, in Japanese Examined Patent Publication No. 60-51424, a turn sheet (lead-tin alloy plated steel sheet) is laminated with a polyvinyl chloride resin coating as a lower layer and an acrylic resin or fluororesin film as an upper layer, and is excellent in corrosion resistance and weather resistance. Decorative steel sheets are described.

Japanese Patent Publication No. 57-27814 discloses a laminated steel sheet in which a lower layer polyvinyl chloride resin film and an upper layer transparent polyethylene terephthalate (PET) resin film are laminated. By backprinting a pattern on the back side of the upper transparent PET resin film,
It is possible to obtain a laminated steel sheet having a pattern and having a high design property.

A general method of manufacturing a laminated metal plate is as follows.
After applying the adhesive to the metal plate, baking and drying the adhesive,
The heated metal plate and the laminating resin film are passed through a laminating roll and bonded together. Even when the laminating resin film is a multi-layer resin film composed of two or more resin films, a laminated resin film prepared by laminating two or more resin films is prepared in advance, and the laminated resin film is used. Laminating with a metal plate in the same manner as above is an efficient method because a laminated metal plate can be manufactured using the same manufacturing apparatus (laminator).

However, when the laminated resin film is laminated by this method, the surface smoothness of the obtained laminated metal plate is not so good, and in particular, the upper resin film layer prints a pattern on the back side of the transparent PET resin film. In the laminated resin film-laminated metal plate composed of the above, the surface irregularities formed during lamination may significantly impair the commercial value of the product.

As a means for eliminating the surface irregularities and improving the image clarity of the laminated metal plate, it is conceivable to heat the obtained laminated metal plate and pass it through a mirror-finished roll for reduction. To improve the smoothness by heating the resin coating and lightly reducing it with a mirror surface roll is disclosed in, for example, Japanese Patent Publication No. 4-11269.
It is also disclosed in the issue. However, the resin coating in this case is a resin coating obtained by coating powder coating,
It has a remarkable surface irregularity called "Yuzu-skin" which is peculiar to powder coatings.

[0007]

A conventional method for improving the clarity of a laminated metal sheet by rolling a roll in a heated state is to remove foreign matter such as dust and dust onto the heated film surface before rolling. Since it adheres, indentation flaws are often generated, and the product yield was extremely low.

Of course, if no foreign matter is present in the line, such a flaw does not occur, but it may be quite difficult to eliminate dust that adheres to and intrudes on a metal plate such as a steel plate. Many. Further, it is not realistic to modify the line so as to remove dust from the entire production line of the laminated metal plate to make it into a clean room, which requires enormous equipment costs. On the other hand, it is conceivable to remove foreign matter from the resin film surface by removing dust from the heated laminated metal plate before rolling it down, but since the resin film has a high temperature of around 150 ° C and is sticky, suction The dust removal with a sticky roll is not effective.

According to the present invention, a laminated metal plate having two or more multi-layered resin film layers laminated with good image clarity and a laminated metal plate for producing such a laminated metal plate with a good yield without requiring a major line modification. And a manufacturing method.

[0010]

Means for Solving the Problems The inventors of the present invention have studied the improvement of the image clarity of a laminated metal plate in which two or more multi-layer resin film layers are laminated, and as a result, the surface roughness of the base metal plate When the softening point of the uppermost resin film and the resin film directly below it is properly selected, the laminated metal plate with high sharpness can be obtained by simply heating it under no-pressure condition after lamination. It was found that it can be manufactured well.

Here, the gist of the present invention is a laminated metal plate in which at least one surface of the metal plate is covered with two or more thermoplastic resin film layers.
The surface roughness of the coated surface of the metal plate is Ra ≦ 1 μm, Rmax
≦ 3 μm, and the softening point or melting point (T _A ) of the resin of the uppermost film and the softening point or melting point (T _B ) of the resin of the film layer immediately below it satisfy the relation of T _A > T _B. A laminated metal plate having excellent image clarity, and a method for producing the laminated metal plate, comprising laminating the two or more resin film layers on the metal plate with an adhesive under heating. Then, after laminating the resin film layer on the metal plate, the obtained laminated body is reheated at a temperature T satisfying T _B <T <T _A in a non-pressurized state.
It is in a method for manufacturing a laminated metal plate.

[0012]

The base material of the laminated metal plate of the present invention includes, but is not limited to, cold rolled steel plates, various plated steel plates, stainless steel plates, aluminum plates and titanium plates. Examples of galvanized steel sheets include galvanized steel sheets such as electrogalvanized steel sheets and hot dip galvanized steel sheets, aluminum plated steel sheets, zinc alloy plated steel sheets, aluminum alloy plated steel sheets, and the like.

The surface roughness of the base metal plate is Ra 1 μm or less and Rmax 3 μm or less. Surface roughness (Ra and Rmax
If one or both) exceeds this value, a laminated metal plate having good image clarity cannot be obtained even if the method of the present invention is applied. The preferred surface roughness of the base metal plate is R
a is 0.5 μm or less and Rmax is 1 μm or less.

The base metal plate may be subjected to an appropriate undercoating treatment in order to improve the adhesion between the adhesive and the base material and the corrosion resistance. For example, when the base material is a zinc-plated steel sheet, it is preferable to perform phosphoric acid-based or chromate-based surface treatment. This base treatment may be carried out according to a conventional method, and the type of base treatment and the adhesion amount are not particularly limited.

The adhesive used for laminating may also be appropriately selected from those capable of satisfactorily adhering the metal plate and the lowermost resin film. For example, an acrylic-based, urethane-based, polyester-based, or epoxy-based adhesive can be used. After applying the adhesive to the metal plate, heat it to an appropriate temperature according to the adhesive used and bake the adhesive.
dry. The application conditions (adhesion amount, baking temperature, etc.) of the adhesive may be the same as conventional ones.

The laminating film in the laminated metal sheet of the present invention is a multi-layer resin film composed of two or more thermoplastic resin film layers. Each of the resins constituting the multi-layer resin film has a softening point or melting point (T _A ) of the resin of the uppermost film layer and a softening point or melting point (T _B ) of the resin of the film layer immediately below the T _A > T _B. Are selected to satisfy the relationship of. That is, in the case of a two-layer film, the melting point or softening point of the upper layer resin is higher than the melting point or softening point of the lower layer resin. In the following, in order to simplify the description, a multi-layer resin film composed of two layers of an upper layer and a lower layer will be described as an example. However, for a resin film having three or more layers, the uppermost film and the film immediately below are the present invention. The effect of the present invention can be obtained by satisfying the relationship defined by.

As a two-layer resin film having a combination satisfying the relationship of T _A > T _B , a lower layer is a polyvinyl chloride resin film (T _B = about 140 ° C.) and an upper layer is a fluororesin film (T _A = about 140 ° C.). 190 ℃) or PET resin film (T
_A = about 250 ° C.) is exemplified. T _A > T _B
Other combinations of two-layer resin films can also be used as long as the above relationship is satisfied.

Although the thickness of each resin film layer is not particularly limited, for example, the lower layer is a polyvinyl chloride resin layer having a thickness of 20 to 200 μm and the upper layer is a fluororesin layer having a thickness of 10 to 50 μm.
Examples thereof include a two-layer resin film, a lower layer is a polyvinyl chloride resin layer having a thickness of 50 to 200 μm, and an upper layer is a polyester resin layer having a thickness of 10 to 100 μm. A printed pattern may be used between the upper layer and the lower layer (on the back side of the upper layer or on the front side of the lower layer) to impart a design property.

The multi-layer resin film for lamination may be used in the form of a laminated resin film in which the respective resin layers are previously bonded by an appropriate adhesive or thermocompression bonding. It is convenient because it can be done. However, it is also possible to manufacture a laminated metal plate in which a multilayer resin film is laminated by sequentially laminating the resin film layer from the lower layer to the metal plate.

Lamination of the multi-layered resin film to the metal plate can be carried out by applying an adhesive and passing the heated metal plate through a laminating roll together with the laminating resin film to adhere them in a conventional manner. . The laminating temperature varies depending on the type of adhesive and the resin type of the film, but when the lower layer is a polyvinyl chloride resin film, it is generally laminated by a rubber roll within the range of 150 to 200 ° C. Lamination may be performed on both sides of the base metal plate, but when used for home electric appliances and building materials, it is usually laminated on only one side.

In this way, the laminated body (laminated metal plate) laminated with the multilayer resin film has a sharpness as it is even if the surface roughness of the base metal plate is limited within the predetermined range as described above. Not good. In particular, when the multilayer resin film has a printed pattern between the upper layer and the lower layer, the pattern may appear as surface irregularities during lamination, and sharpness may be significantly impaired.

In the method of the present invention, the laminate obtained by laminating is reheated at a temperature T satisfying T _B <T <T _A in a non-pressurized state. By the reheating at this temperature T, the upper layer resin film does not melt or soften, but the elastic force at the high temperature acts as a driving force for smoothing, the surface unevenness of the upper layer resin film is eliminated, and the surface smoothness is eliminated. Be promoted. On the other hand, since the lower resin film is melted or softened by reheating at the temperature T and becomes fluid,
It can flow following the smoothing of the upper resin film. Therefore, the smoothing of the upper layer resin film is not hindered by the presence of the lower layer resin film adhered thereto.

That is, without rolling down the roll, the high temperature fluidity of the lower layer resin and the elastic modulus of the upper layer resin at high temperature can be utilized to improve the image clarity by smoothing the surface. The higher the fluidity of the lower layer resin and the higher the elastic modulus of the upper layer resin, the greater the effect of improving the image clarity. Generally, as the thermoplastic resin becomes higher in temperature, the viscosity and elastic modulus decrease remarkably, so depending on the combination of the resin of the upper layer and the lower layer and the film thickness thereof,
The reheating temperature and the holding time (line speed) are appropriately set so as to obtain the desired image clarity.

For example, when the lower layer is a polyvinyl chloride resin and the upper layer is a fluororesin, the reheating treatment condition is a temperature of 150.
A temperature of ~ 180 ° C and a holding time of 60 seconds are suitable. If the lower layer is polyvinyl chloride resin and the upper layer is PET resin, the temperature 1
Reheating is preferably performed at 50 to 230 ° C. for a holding time of about 60 seconds.

The reheating may be carried out after the laminated body is cooled after the laminating, or may be carried out as it is after the laminating without being forcibly cooled. It is advantageous to continuously reheat the laminated body obtained after the lamination without cooling, because it is thermally resource-saving, and in that case, a post-heater is required after the laminator. As the heater, any conventional heating device such as a hot air type, an induction heating type or an infrared type may be used.

When a post heater cannot be provided in the laminate manufacturing facility, the laminate may be rapidly cooled (eg, water-cooled, air-cooled) or allowed to cool after lamination, and once wound into a coil. In that case, the coiled laminate is unwound and reheated in a separately provided heating device.

By this reheating treatment, the surface of the laminated multi-layer resin film is smoothed, and a laminated metal plate having remarkably improved image clarity can be obtained. However, after cooling, the laminated surface can be covered with a turn roll or a recoiler. When the material is subjected to pressure reduction, it is preferable to remove dust and dirt by means such as suction or an adhesive roll to prevent the occurrence of indentation flaws. In the cooled state, since the film surface has no adhesiveness, such dust removing means effectively functions.

The laminated metal sheet of the present invention has a distortion of 40 or more, preferably 70 or more, and a contrast of 40 or more, preferably 60 or more as measured by NSIC (Nippon Paint-Suga Test Instruments image clarity measuring device). Excellent image clarity. On the other hand, as illustrated in the following examples, even if the surface roughness of the base material and the type of the multilayer resin film satisfy the conditions of the present invention, reheat treatment is not performed or the conditions are If it goes out of the range of the present invention, the sharpness is remarkably lowered. Further, when the surface roughness of the base material becomes large outside the range of the present invention, it becomes impossible to obtain a remarkable improvement in the image clarity by the reheating treatment.

According to the present invention, it is possible to obtain a laminated metal plate having excellent image clarity without performing reduction in a heated state where push-in flaws are likely to occur, so that the product yield is remarkably improved.

[0030]

Example 1 As a base metal plate, Ra = 0.5 μm, Rmax = 1.0 μm
Using a double-sided hot-dip galvanized steel sheet (60/60 g / m ² , coating thickness 0.5 mm) with skin pass treatment, one side is coated with chromate treatment (Cr deposition amount = 60 mg /
m ² ), an acrylic adhesive (Sony Chemical: SC 610) was applied thereon at a thickness of 5 g / m ² , and dried and baked (180 ° C. × 60 seconds).

As a multilayer resin film for lamination, a polyvinyl chloride / PET two-layer film (manufactured by Riken Vinyl Co., Ltd.) laminated in advance was used and laminated so that the polyvinyl chloride resin layer was a lower layer. The film thickness of each layer was 100 μm for polyvinyl chloride and 25 μm for PET, and the softening points were about 140 ° C. (= T _A ) for polyvinyl chloride resin and about 250 ° C. (= T _B ) for PET resin. .

Using a continuous laminating device having a hot air oven as a post heater at a position about 5 m behind the laminating roll, baking and drying of the adhesive were completed, and the adhesive was preheated to the laminating temperature (150 ° C or 200 ° C). The above two-layer film was laminated on the adhesive layer of the hot-dip galvanized steel sheet and reheated in a hot air oven as it was. The reheating temperature was the maximum plate temperature reached in the oven, and the reheating time was the length of the hot air oven divided by the line speed.

The image clarity of the laminated steel sheet obtained after cooling was measured for distortion and contrast by NSIC. The results are shown in Table 1 below together with the lamination temperature and the reheating treatment conditions.

[0034]

[Table 1]

As can be seen from Table 1, when the reheating temperature is lower than the softening point of the polyvinyl chloride resin of the lower layer even after the reheating treatment (Test Nos. 2 and 5), no reheating was performed.
Only the same level of image clarity as (Test Nos. 1 and 4) was shown, and improvement in image clarity by reheating was not obtained. In contrast,
According to the present invention, when the reheating treatment was carried out at a temperature higher than the softening point of the polyvinyl chloride resin of the lower layer and a lower temperature than the softening point of the PET resin of the upper layer, a remarkable improvement in sharpness was obtained in any test ( Test No. 3, 6, 7).

Comparative Example 1 A laminated steel sheet was prepared in the same manner as in Example 1 except that a single-sided electrogalvanized steel sheet with Ra = 2 μm and Rmax = 4 μm (plating adhesion amount: 40 g / m ² ) was used as the base metal plate. The production and reheat treatment were performed, and the image clarity of the obtained laminated steel sheet was evaluated in the same manner. The laminating temperature was 150 ° C. The processing conditions and results are shown in Table 2 below.

[0037]

[Table 2]

When the surface roughness of the base steel sheet is large, even if reheating after lamination is carried out under the conditions within the scope of the present invention, the effect of improving the sharpness is small, and the laminated steel sheet excellent in the sharpness is obtained. Couldn't get

[0039]

EFFECTS OF THE INVENTION The image clarity of a laminated metal plate significantly affects the commercial value. Especially, in the case of a conspicuous application such as a refrigerator door, the one with low image clarity cannot be used. The laminated metal plate of the present invention exhibits high image clarity suitable for such applications. Further, since the laminate film is a multi-layer resin film having two or more layers, it is possible to give the film a specific function such as designability and high durability due to the pattern.

Polyvinyl chloride / PE with a design pattern
Since the price of T2 layer film and highly durable polyvinyl chloride / fluorine resin two layer film is high, the product yield has a great influence on the production cost in the production of a laminated metal plate laminated with these two layer films. give. According to the method of the present invention, since there is no occurrence of indentation defects due to dust or the like accompanying the roll pressure under heating,
It is possible to manufacture the above-described laminated metal plate having high image clarity with a high product yield and without requiring a major modification of manufacturing equipment.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Akihiro Yauchi 4-5-3 Kitahama, Chuo-ku, Osaka City Sumitomo Metal Industries Co., Ltd. (72) Inventor Toshiaki Shiota 4-53-3 Kitahama, Chuo-ku, Osaka Issue Sumitomo Kinzoku Kogyo Co., Ltd. (72) Inventor Nagaharu Tanaka 2 Dejima Nishimachi Sakai City Igeta Steel Plate Co., Ltd. (72) Inventor Susumu Kameda 2 Dejima Nishimachi Sakai City Igeta Steel Co., Ltd. (72) Inventor Tomohiro Actually, 2 Dejima Nishimachi, Sakai City, Igeta Steel Co., Ltd. (72) Inventor, Kazuhiro Kuroki 2 Deshima Nishimachi, Sakai City, Igeta Steel, Co., Ltd.

Claims (2)

[Claims] 1. A laminated metal plate in which at least one surface of the metal plate is coated with two or more thermoplastic resin film layers, and the surface roughness of the coated surface of the metal plate is Ra ≤1.
μm, Rmax ≦ 3 μm, and the softening point or melting point (T _A ) of the resin of the uppermost film and the softening point or melting point (T _B ) of the resin of the film layer immediately below have a relationship of T _A > T _B. A laminated metal plate with excellent image clarity, which is characterized by satisfying. 2. The method for producing a laminated metal plate according to claim 1, wherein the two or more resin film layers are laminated on the metal plate via an adhesive under heating. _A method for producing a laminated metal plate, comprising: laminating on a metal plate and then reheating the obtained laminate at a temperature T satisfying T _B <T <T _A in a non-pressurized state.