JPH07100989A - Manufacture of laminated metal plate - Google Patents

Abstract

PURPOSE:To prevent deformation vanishment of an uneven part of a film surface without reducing adhesive properties of the film by coating a metal plate in which its substrate is processed with adhesive, baking it, then forcibly cooling the plate, and laminating a thermoplastic film at a specific temperature. CONSTITUTION:After a metal plate in which its substrate is processed with phosphate or chromate is coated with adhesive and baked, the plate is forcibly cooled, and a thermoplastic resin film is laminated at a temperature of a film softening point or lower and (a film softening temperature -30 deg.C) or higher. The adhesive which contains acryl, polyester, epoxy or urethane as a base and crosslinker added thereto is preferable. As the cooling method, a forcible cooling is conducted by using a mist cooler or an air cooler at an oven output side for baking. The film is preferably vinyl chloride or fluorine film.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a laminated metal sheet suitable for home electric appliances, interior building materials and the like, which is excellent in design and adhesion.

[0002]

2. Description of the Related Art Conventionally, a metal plate laminated with a vinyl chloride film has been widely used for home electric appliances such as VCRs and microwave ovens and decorative metal building materials. In addition, a metal plate laminated with a fluorine-based film is used for a soundproof wall of a highway.

These laminated metal sheets are required to have high designability as well as durability, and the requirement is particularly strong for home electric appliances and interior building materials.

The designability of the laminated metal sheet is, for example, the gloss level of the surface. This gloss is generally determined by the surface roughness of the laminating film. That is, during film production, the surface irregularities of the chill roll that cools the film-shaped molten resin discharged from the extruder are transferred to the film surface. When the irregularities are large, the gloss decreases, and when the irregularities are small, the gloss increases.

The surface gloss level of a laminated metal sheet has become popular, and recently, a so-called matte matte finish is often required. In that case, the unevenness of the film surface is increased.

On the other hand, a laminated metal plate is usually manufactured by
It is carried out by applying an adhesive on a metal plate which has been subjected to a phosphate or chromic acid base treatment, baking it, and then laminating the film.

Here, it is said that the higher the temperature during lamination, the better the adhesiveness of the film. Therefore, the adhesive is baked and then laminated, and the temperature at the time of baking is taken over by the laminate.

[0008]

However, in such a conventional method for producing a laminated metal plate, even if large irregularities are formed on the film surface, the surface is leveled during lamination, and There is a problem that gloss increases.

That is, in the conventional manufacturing method, since the temperature at the time of baking is taken over by the laminate, the laminating temperature is about [baking temperature− (10 to 20) ° C.]. As the baking temperature of the adhesive, for example, about 200 ° C. is adopted. In that case, the laminating temperature is 180-
It becomes about 190 ° C. However, since the film is a thermoplastic resin, whether it is a vinyl chloride film or a fluorine-based film, it softens at about 150 ° C. for a vinyl chloride film and about 170 ° C. for a fluorine film. Therefore, the film is softened at the time of lamination and the surface irregularities disappear.

When the baking temperature of the adhesive is lowered, the laminating temperature is lowered accordingly, and it is possible to prevent the unevenness from disappearing in the laminating, but such a temperature lowering is said to lead to a lowering of the adhesiveness of the film.

It is an object of the present invention to provide a method for producing a laminated metal plate which can prevent the deformation and disappearance of the unevenness provided on the film surface without lowering the adhesiveness of the film.

[0012]

Means for Solving the Problems It is necessary to consider the adhesiveness of a film in a laminated metal plate by dividing it into two: an adhesiveness between a base treatment layer and an adhesive layer, and an adhesiveness between an adhesive layer and a film. . Regarding the processing temperature, it is necessary to distinguish between the baking temperature of the adhesive and the temperature at which the film is laminated.

The inventors of the present invention have investigated the factors affecting the adhesiveness of the laminated film by paying attention to these points, and found that the poor adhesion of the film results in poor softening due to insufficient baking temperature of the adhesive. The effect of insufficient adhesion between the undercoat layer and the adhesive layer is large, and when the baking temperature of the adhesive is decreased by the conventional manufacturing method, the adhesiveness of the film is decreased because the decrease of the baking temperature itself. The lowering of the laminating temperature due to the lowering of the baking temperature does not significantly affect the adhesiveness of the film.If the baking temperature of the adhesive is sufficient, the film temperature will be low during lamination. Also, sufficient adhesiveness can be secured, after the film laminating temperature is independent of the adhesive baking temperature, after the adhesive is baked on the metal plate It has been found that if the metal plate is forcibly cooled, it is possible to prevent deformation and disappearance of irregularities on the film surface without lowering the adhesiveness of the film.

The present invention has been made on the basis of such findings, and in the production of a laminated metal plate coated with a thermoplastic resin film, an adhesive is applied onto a metal plate subjected to a phosphate or chromic acid base treatment. And baking, the metal plate is forcibly cooled, and a thermoplastic resin film is laminated at a temperature not higher than the film softening point and not lower than (film softening point −30 ° C.), thereby producing a laminated metal plate. The method is the gist.

A method of controlling the temperature of a roll used for laminating, specifically, a method of lowering the temperature of an upper roll in contact with a film, for the purpose of preventing disappearance of irregularities on the film surface, is disclosed in JP-A-63 / 1988. No. 168333 is disclosed. In such roll temperature control,
If the upper roll is a metal roll, the heat transfer is good, so the film surface temperature can be lowered in a short time and the change in the film gloss can be prevented, but it is difficult to pass the plate because the plate warps, It is difficult to make it. Further, when the upper roll is made of rubber, heat transfer is poor, and the film gloss cannot be maintained even if the roll temperature is controlled.

[0016]

The function of the present invention will be described in detail below for each step.

[0017] performing a surface treatment on the surface of the base-treated metal plate.

The metal plate is not particularly limited, and examples thereof include various plated steel plates, stainless steel plates, aluminum plates and the like which are usually used as a base material for laminated metal plates. The plating may be hot dip galvanizing, alloy hot dip galvanizing, hot dip galvanizing containing Al, electrogalvanizing, Ni—Zn alloy plating, or the like.

As the base treatment, well-known phosphate type and chromate type are used. The amount of adhesion is 0.3 to 1.
0 g / m ^2, about 20-100 mg / in chromate system
About m ² is desirable. The chromate-based treatment liquid may contain silica or phosphoric acid.

Application and Baking of Adhesive Agent An adhesive agent is applied and baked on a metal plate which has been subjected to a base treatment.

The adhesive is preferably based on an acrylic resin, polyester resin, epoxy resin, urethane resin or the like, to which a crosslinking agent such as melamine, amine or isocyanate is added. Of course, it is possible to include silica, calcium carbonate, titania, etc. as an extender pigment, and strontium, chromate, zinc chromate, etc. as rust preventive pigments.

Regarding the coating method, for example, a dry film thickness of about 1 to ²⁰ g / m ² is applied by a conventional means such as a roll coater.

Baking cures the applied adhesive. The adhesive contains solvents such as xylene and cyclohexanone, and these solvents are dried during baking and softening.

As the baking conditions, for example, a maximum reaching temperature of 120 to 250 ° C. and a time of 30 to 80 seconds are selected depending on the kind of the adhesive. In the present invention, the metal plate is forcibly cooled after baking, so that the film It is not necessary to intentionally lower the baking temperature to ensure adhesion. Rather, a sufficient baking temperature should be ensured to accelerate the curing of the adhesive and enhance the adhesion between the surface treatment layer and the adhesive layer.

Forced Cooling This is an important step in the present invention, and the metal plate on which the adhesive has been baked is forcibly cooled before being laminated.

As a cooling method, for example, a metal plate is forcibly cooled by using a mist clerer or an air cooler on the outlet side of a baking oven.

The cooling temperature is basically the laminating temperature which will be described later, but the metal plate may be once cooled to near room temperature by water cooling or the like and then reheated to the laminating temperature with a hot air oven or an infrared oven. If there is a laminating facility on the CCL (continuous coating facility) output side, No.
It is used to coat and cure the adhesive with one coater and heat the No. 2 oven to the laminating temperature.

The film is laminated on the metal plate adjusted to the laminating temperature by laminating cooling or reheating after cooling via an adhesive layer.

In a conventional general laminating line, the baking temperature is set to 1 because the baking temperature is designed to be used on the outlet side of the baking oven.
If the temperature is 70 ° C, the laminating temperature will be about 160 ° C.
When the softening point of the film is 150 ° C., unevenness on the film surface disappears during lamination, and gloss is exhibited. That is, the laminating temperature is under the influence of the baking temperature, and it has been difficult in many cases to satisfy both the recent high demand for gloss and the severe adhesive performance.

However, in the present invention, the lamination temperature is secured without being affected by the baking temperature by cooling before laminating or reheating after laminating.

The laminating temperature is set to be not higher than the softening point of the film used and not lower than (softening point −30 ° C.). When the laminating temperature exceeds the softening point of the film, the matte unevenness formed on the surface of the film disappears at the time of the laminated metal plate, and gloss appears. However, when the laminating temperature is lower than (softening point −30 ° C.), the adhesion of the film to the adhesive is not promoted, resulting in insufficient adhesion.

Such a laminating temperature is considerably lower than the conventional laminating temperature, but in the present invention, a high temperature can be secured in the step of baking the adhesive, and that temperature is dominant for the adhesiveness of the film. Therefore, even if the laminating temperature is lowered, the adhesion failure of the film does not occur.

When the laminating temperature is lowered by the conventional manufacturing method in which the laminating temperature is affected by the baking temperature,
Due to the decrease in the baking temperature accompanied with this, defective adhesion of the film cannot be avoided.

A thermoplastic resin film is used as the film. The type of the present invention is not limited, but the present invention is particularly effective for vinyl chloride and fluorine type. These films have a large change in surface unevenness due to heat, and the conventional manufacturing method in which the laminating temperature is under the influence of the baking temperature, when the baking temperature is increased for the purpose of ensuring adhesiveness,
As a result of the increase in the laminating temperature, the unevenness on the surface disappears, and the expected matting property cannot be obtained.

The applicant of the present invention has developed an adhesive having excellent adhesiveness even at low temperatures in order to lower the laminating temperature under the influence of the baking temperature (Japanese Patent Application No. 4-3392), but in the present invention, the laminating temperature is Is not under the influence of the baking temperature, there is no need to use such a special adhesive.

[0036]

EXAMPLES Next, examples of the present invention will be described, and the effects of the present invention will be clarified by comparing them with comparative examples.

Example 1 A hot-dip galvanized steel sheet (sheet thickness 0.5 mm, coating weight 120 g / m ² ) was used as a base material. After degreasing and washing with water on the plated steel sheet, zinc phosphate treatment (deposition amount of 0.
5 g / m ² ) was applied. Fine Tough C (for fluorine-based film) made by Dainippon Ink Co., Ltd. was applied as an adhesive to the plated steel sheet after the base treatment by a bar coater. Adhesion amount is 7g /
It was set to m ² . The coated steel sheet after coating was passed through an infrared oven to bake the adhesive at various temperatures. The baked steel sheet was forcibly cooled by an air cooler provided on the outlet side of the oven to change the laminating temperature. Further, some of the steel sheets were water-cooled to around room temperature and then reheated to the laminating temperature in the next pass. A DX film manufactured by Denki Kagaku KK was laminated on the steel plate after cooling or after reheating. This film is a fluorine-based film composed of a mixed component of vinylidene fluoride / acryl, and has a film thickness of 40 μm and a softening point of 175 ° C.
Met. The initial glossiness (60 ° gloss) is about 5
And, it was almost completely matte.

The softening point is Thermal Mech manufactured by Shimadzu Corporation.
Anical Analysis TM type is used, the tip glass diameter is 1mm,
It was measured by investigating the change in the penetration distance of the glass rod under the conditions of an initial load of 10 g and a temperature rising rate of 10 ° C./min.

The glossiness (60 gloss) of the various laminated steel sheets produced was measured. In addition, after making a 2 mm grid-shaped cut in the laminate film and projecting 8 mm Erichsen, a peel test with tape is performed to investigate the initial adhesion, and a peel test is performed after immersion in boiling water for 4 h to perform secondary adhesion. The properties were investigated, and those without peeling were evaluated as ◯, partial peeling as Δ, and entire surface peeling as ×. The results are shown in Table 1.

[0040]

[Table 1]

Nos. 1 to 4 are cases where the baking temperature is 240 ° C. In No. 1 where forced air cooling is not performed after baking, the laminating temperature is much higher than the film softening point.
At 20 ° C., the adhesiveness was good, but the unevenness on the film surface disappeared almost completely, and the matte property was lost.
Even in No. 2 which was subjected to weak air cooling, the matting property was considerably lowered because the laminating temperature exceeded the softening point.

On the other hand, in Nos. 3 and 4 in which the laminating temperature was adjusted in the range of the softening point to (softening point −30 ° C.) by air cooling or reheating after air cooling, the unevenness of the film surface remained as it was after laminating. , The original mattness was maintained. Regarding the adhesiveness, since the baking temperature is high,
Of course, good results were obtained.

Nos. 5 to 7 are cases where the baking temperature was 200 ° C. In No. 5 which was not subjected to forced cooling, although the adhesion was good, a slight gloss was generated because the laminating temperature exceeded the film softening point. In No. 6 which was weakly air-cooled, the adhesion was good and no gloss was generated. Air cooled No. 7
Then, the lamination temperature becomes less than (softening point -30 ° C),
Instead of producing no gloss, the adhesion was significantly reduced.

Nos. 8 and 9 are cases in which the matting property was tried to be secured without performing forced air cooling. In No. 8, the secondary adhesion was lowered because the baking temperature was lowered to 170 ° C, and in No. 9, the secondary adhesion was further decreased because the baking temperature was lowered to 150 ° C. In particular, as shown in No. 8, the laminating temperature is from softening point to (softening point −30
Even if it is in the range of (° C.), if the baking temperature is low, the adhesiveness is insufficient.

As described above, when air cooling is not performed after baking, the laminating temperature is affected by the baking temperature. Therefore, if the adhesiveness is prioritized, the laminating temperature is increased and the matting property is lost (No. 1, 5). ), If priority is given to maintaining the matting property, the baking temperature will decrease and the adhesive property will decrease (No. 8, 9).

Example 2 The same base material as in Example 1 was coated with chromate (50 mg / m ² ) as a base treatment. SC601 (acrylic adhesive) manufactured by Sony Chemicals was applied to the plated steel sheet as an adhesive. The adhesion amount was 5 g / m ² . And
The plated steel sheet was baked in the same manner as in Example 1, then forcibly cooled, and then laminated with a Riken vinyl salt film. The film thickness is 80 μm and the softening point is 1.
At 45 ° C, the initial glossiness was 30 (60 gloss).

Table 2 shows the results of evaluation of glossiness and adhesiveness of the produced laminated steel sheet in the same manner as in Example 1.
The present invention is also effective for a steel sheet laminated with a vinyl chloride film, and by the forced cooling and control of the laminating temperature, it is possible to satisfy both high requirements for gloss and strict adhesion performance.

[0048]

[Table 2]

[0049]

As described above, according to the method for producing a laminated metal plate of the present invention, the film is formed on the film surface while ensuring excellent film adhesiveness by performing forced cooling after baking the adhesive. It is possible to prevent deformation and disappearance of unevenness and to satisfy high requirements for gloss.

Front page continued (72) Inventor, Yoshida, 4-5-3 Kitahama, Chuo-ku, Osaka-shi, Osaka Prefecture Sumitomo Metal Industries, Ltd. (72) Inventor, Katsuji Kawanishi, 4-53, Kitahama, Chuo-ku, Osaka, Osaka No. Sumitomo Metal Industries, Ltd.

Claims (1)

[Claims] 1. In the production of a laminated metal sheet coated with a thermoplastic resin film, an adhesive is applied to a phosphate- or chromic acid-based undercoating-treated metal sheet and baked, and then the metal sheet is removed. It is forcibly cooled to a temperature below the film softening point ((film softening point-3
A method for producing a laminated metal plate, which comprises laminating a thermoplastic resin film at a temperature of 0 ° C. or higher.