JP2002178406A - Method for manufacturing thermoplastic resin film- coated aluminum plate having excellent strength, processability and adhesive properties - Google Patents

Abstract

PROBLEM TO BE SOLVED: To sufficiently secure adhesive properties and processability of a film without lowering the strength of an Al plate at laminating even when a thermoplastic resin film-coated Al plate having a relatively high melting point such as a polyester or the like is to be manufactured. SOLUTION: A method for manufacturing the thermoplastic resin film-coated aluminum plate comprises a first step of heating the Al plate at a temperature of a glass transition temperature to lower than a melting point (Tm), laminating the resin film on at least one surface of the Al plate, pressurizing the film by a laminating roll to temporarily adhere the film, and a second step of subsequently heating the resin film so as to become a temperature of Tm to Tm+30 deg.C. In the second step, the heating up to the Tm is executed by an induction heating method and the heating exceeding the Tm is executed by an infrared heating method.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a resin film-coated aluminum plate obtained by laminating a thermoplastic resin film on one or both surfaces of an aluminum plate. The present invention relates to a method for producing a thermoplastic resin-coated aluminum plate laminated with a thermoplastic resin film having a relatively high melting point of higher than ° C.

[0002]

2. Description of the Related Art Conventionally, a resin film-coated metal plate obtained by laminating a resin film on one or both surfaces of a metal plate has been widely used in various fields such as electric parts, furniture, and interior and exterior building materials. In recent years, the objective has been to protect the environment by reducing emissions of VOCs (volatile organic solvents) and CO ₂ , and to improve the stability and quality of contents by using the high barrier properties of polyester films. As
2. Description of the Related Art Polyester film-coated metal plates are frequently used for container materials such as beverage cans.

As a method of continuously laminating a thermoplastic resin film on a metal plate using a thermoplastic resin such as polyester as a resin film, for example, as disclosed in Japanese Patent Publication No. 2-58094, The plate is heated to a temperature equal to or higher than the melting point of the thermoplastic resin film, and in that state, the thermoplastic resin film is laminated on one or both surfaces of the metal plate, heated and pressed by a temperature-controlled laminating roll, and then immediately cooled, Alternatively, there is known a method of performing a heat treatment as a post-treatment and then cooling.

On the other hand, as a resin film to be laminated on a metal plate, a film having a single-layer structure made of a single resin is used, or a resin film having a different melting point as shown in Japanese Patent Application Laid-Open No. 2-501640. 2 using more than one kind of resin
In some cases, a film having a plurality of layers or more is used, and an adhesive layer may be interposed between the metal plate and the resin film. In addition, as such a resin film, generally, a biaxially stretched film is often used.

[0005] The heating temperature of the metal plate when laminating the resin film on the metal plate varies depending on the purpose of use of the metal plate coated with the resin film, but the high adhesion between the resin film and the metal plate and the processing of the resin film. In order to secure the property, the metal plate is often heated to a high temperature equal to or higher than the melting point of the resin film. Generally, as a heating method, various methods such as a hot air heat transfer method, an electric heating method, an induction heating method, a heat roll heat transfer method, and an infrared heating method are known, but immediately before laminating a resin film to a metal plate. In order to heat a metal plate, a heat roll heat transfer method is often used, and an induction heating method is often used for heat treatment after lamination.

[0006]

In laminating a thermoplastic resin film on a metal plate, in order to ensure high adhesion and workability of the resin film, it is necessary to heat at least a temperature higher than the glass transition temperature of the thermoplastic resin. In some cases, heating to a temperature higher than the melting point of the thermoplastic resin may be required. However, in such a case, the strength of the metal plate may be reduced by heating. In particular, the melting point of the thermoplastic resin is 20 such as polyester, polyamide, and fluorine resin.
If a resin exceeding 0 ° C. is used and an aluminum plate is used as the metal plate, there is a strong concern.

On the other hand, recently, as described above, a resin film-coated metal plate is often used for a beverage can. In that case, polyester is often used as the resin film, and an aluminum plate is often used as the metal plate. For such aluminum beverage cans, it is strongly desired to reduce the weight by thinning the wall. Therefore, in order to ensure sufficient pressure resistance even with a thin wall, it is desired to use a material having a high strength.
As described above, if a resin film is laminated at a high temperature in order to secure the adhesion of a resin film such as polyester, the demand for thinning may not be sufficiently satisfied due to a decrease in the strength of the aluminum plate.

The present invention has been made in view of the above circumstances. Even when a thermoplastic resin having a relatively high melting point exceeding 200 ° C., such as polyester, is used, aluminum is not used when laminating a thermoplastic resin film. An object of the present invention is to provide a resin film-coated aluminum plate capable of sufficiently securing the adhesion and workability of a resin film without causing a decrease in the strength of the plate, and a method for manufacturing the same.

[0009]

Means for Solving the Problems In order to solve the above-mentioned problems, the present inventors have conducted intensive experiments and studies, and as a result,
After heating the aluminum plate to an appropriate temperature range, laminating the thermoplastic resin film on the aluminum plate, and pressurizing and temporarily bonding by a laminating roll, as a heating means for the aluminum plate and the resin film, in particular, a heating furnace using an induction heating method. In combination with a heating furnace by infrared heating method,
By heating the resin film to an appropriately adjusted temperature range, it was possible to secure strong adhesion of the laminated resin without lowering the strength of the aluminum plate, and it was also found that the workability was also improved, and the present invention was found. I've reached the point.

More specifically, the invention of claim 1 is a method of manufacturing a thermoplastic resin film-coated aluminum plate by laminating a thermoplastic resin film on an aluminum plate. A first step of heating to a temperature within the range of not less than the temperature and less than the melting point (Tm), laminating a thermoplastic resin film on at least one surface of the aluminum plate, pressing with a laminating roll, and temporarily bonding, Subsequent to the first step, the temperature of the resin film is equal to or higher than Tm and (Tm + 3
0) a second step of heating to a temperature of not more than 0 ° C. In the heating of the second step, if the heating temperature of the second step is T2, the heating up to Tm is performed by an induction heating method, The heating from T2 to T2 is a method for producing a thermoplastic resin film-coated aluminum plate, wherein the heating is performed by an infrared heating method.

According to a second aspect of the present invention, there is provided a method for producing a thermoplastic resin film-coated aluminum plate by laminating a resin film having a multilayer structure composed of two or more thermoplastic resins on an aluminum plate. Heat to a temperature not lower than the glass transition temperature of the resin of the layer in contact with the aluminum plate in the thermoplastic resin film and less than the melting point of the resin of the outermost layer in the resin film, and apply the resin film to at least one surface of the aluminum plate. A first step of laminating and pressurizing with a laminating roll and temporarily bonding, and subsequent to the first step, with respect to the melting point (Tm ₁ ) of the resin having the highest melting point among the resins of the respective layers constituting the resin film. the second step of heating to be within a range temperature and the Tm ₁ or more _(Tm 1 + 30 ℃) or less of the resin film From it, yet at the heating of the second step it is heated up to the melting point Tm ₂ of resin film layer in contact with the aluminum plate is performed by induction heating system, beyond the _{Tm 2 (Tm 1 + 30 ℃} ) to within the range of The heating is performed by an infrared heating method, which is a method for producing an aluminum plate coated with a thermoplastic resin film.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The upper part (A) of FIG. 1 shows a conceptual structure of an apparatus for carrying out the method of the present invention by a continuous laminating method, and the lower part (B) of FIG. FIG. 1A shows changes in the temperature of the aluminum plate and the temperature of the thermoplastic resin when the thermoplastic resin is continuously laminated. FIG. 1
Shows an example in which a resin film is laminated on both sides of an aluminum plate. Further, in the following description, first, the overall configuration of the invention will be described in the case of laminating using a resin film having a single-layer configuration, and then, the case of using a resin film having a plurality of layers will be described.

In FIG. 1A, the aluminum plate 1 is, for example, previously formed as a coil, and the coiled aluminum plate 1 is continuously fed from the supply side reel 3 while passing through the first heating means 5. The glass transition temperature (Tg) of the resin of the thermoplastic resin film to be laminated,
It is heated to a temperature T1 within a range below the melting point (Tm). Subsequently, the aluminum plate 1 reaches between a pair of upper and lower laminate rolls (pressure rolls) 7A and 7B. At a position immediately before the laminating rolls 7A and 7B, the thermoplastic resin films 9A and 9B to be laminated are continuously supplied to one side or both sides (both sides in the illustrated example) of the aluminum plate 1, and are laminated by the laminating rolls 7A and 7B. It is pressed and bonded to the surface of the aluminum plate 1 in a temporary bonding state. The steps so far correspond to the first step in the method of the present invention. Then, with the thermoplastic resin temporarily bonded as described above, the aluminum plate 1 is
After passing through the heating means 12, the thermoplastic resin films 9A and 9B are heated to a temperature (Tm + Tm + 30 ° C.) (Tm
Heated to 2). This step corresponds to the second step in the method of the present invention. Here, in the case of the present invention, in particular, as the second heating means 11, a heating means of an induction heating method is applied to perform heating up to Tm, and as a third heating means 12, a heating means of an infrared heating method is applied, and
Heat up to 2. Then, after the resin film is heated by the second heating means of the induction heating method and the third heating means of the infrared heating method and laminated on the aluminum plate, and then cooled by the cooling device 13, the laminated aluminum plate 1 It is wound continuously on the winding reel 14.

First, the first step will be described. The first step is a step of heating the aluminum plate, laminating a thermoplastic resin film on one or both surfaces thereof, and pressing the laminate roll to temporarily adhere the thermoplastic resin film to the surface of the aluminum plate. The purpose of heating the aluminum plate in the process is to soften the thermoplastic resin film in contact with the aluminum plate and temporarily bond the film to the aluminum plate by pressing with a laminating roll. If the heating temperature in the first step is lower than the glass transition temperature of the resin, the softening of the resin film becomes insufficient, and the resin film may not be sufficiently adhered to the surface of the aluminum plate due to the entrainment of air or the like. On the other hand, the higher the heating temperature, the higher the adhesion can be obtained. However, if the heating temperature is higher than the melting point of the resin, the resin film is melted and adheres to the laminating roll, which causes a problem that the lamination cannot be performed smoothly. Therefore, the heating temperature of the aluminum plate in the first step needs to be in a temperature range not lower than the glass transition temperature of the resin constituting the resin film to be used and lower than the melting point.

The first heating means for heating the aluminum plate in the first step is not particularly limited, but may be a roll heating method, a hot air heating method, an infrared heating method, or the like.
Any method such as an electric heating method and an induction heating method may be applied. However, among these, the roll heating method is the most suitable in terms of making the temperature distribution uniform and efficient.

The surface temperature of the roll when pressurized by the laminating roll is not particularly limited, but is generally set to be slightly lower than the temperature of the aluminum plate. The pressure applied by the laminating roll is not particularly limited, but is generally 2 kgf / cm (19.6 N /
cm) or more is appropriate. If the pressing force by the laminating roll is less than 2 kgf / cm (19.6 N / cm) in a linear pressure, there is a possibility that a sufficient adhesion force cannot be obtained. The upper limit of the pressing force is not particularly limited, but may be a common sense pressure that does not damage the device.

Next, the second step will be described. The thermoplastic resin film temporarily bonded to the surface of the aluminum plate as described above is heated by an induction heating method up to the melting point range of less than Tm, and is heated by infrared heating up to the range of Tm + 30 ° C. or less beyond Tm. Heat according to the method.

The first purpose of the heating in the second step is to bond the resin film to the surface of the aluminum plate with a sufficient adhesion. That is, the resin film temporarily bonded in the first step is further softened and melted to remove air entrapped between the aluminum plate and the film, and to form fine recesses such as rolls and oil pits on the surface of the aluminum plate. The purpose of the present invention is to allow the resin of the film to penetrate into the aluminum plate and to firmly adhere the film to the aluminum plate.
In addition, even when the chemical conversion treatment was performed on the aluminum plate surface,
The shape of the concave portions such as the rolls and oil pits on the plate surface does not change significantly, and therefore, the same effect can be obtained even if the chemical conversion treatment is performed.

A second object is to break down the orientation of the oriented and crystallized resin film and to impart good workability to the film. That is, in general, a film oriented and crystallized by biaxial stretching is often used as a resin film for lamination, and since the oriented crystallized state does not have sufficient workability, the finally obtained resin is When the film-coated aluminum plate is pressed, the resin film may be cracked or broken, making the processing difficult. Therefore, in order to impart sufficient workability, it is necessary to collapse the orientation by heating.

The heating temperature of the resin film in the second step for these purposes must be in the range of Tm or more and Tm + 30 ° C. or less. That is, if the heating temperature of the resin film in the second step is lower than Tm, the resin film does not sufficiently advance in softening and melting, so that a high adhesion force cannot be obtained. Further, the processability is inferior because the collapse of the orientation of the resin film is not sufficient, so that the resin film may be cracked or broken at the time of processing, making the processing difficult. Therefore, the lower limit of the heating temperature of the resin film in the second step was Tm. The heating temperature is Tm
If the temperature is higher than + 30 ° C., a part of the molecular structure constituting the resin film may be cut off. In such a case, the film surface may be roughened or cracked during processing. When heating such as retort treatment is performed, peeling or whitening of the resin film may occur. Therefore, the upper limit of the heating temperature of the resin film in the second step was Tm + 30 ° C.

Here, as the heating method in the second step, it is necessary to use both the induction heating method and the infrared heating method and switch the heating method at a predetermined temperature. This is an important point in the present invention.

As described above, the purpose of the heating in the second step is to improve the adhesion and workability of the resin film. Generally the second
Since the heating temperature in the step is set to be higher than the heating temperature in the first step, the strength of the coated aluminum plate is usually determined by the heating temperature in the second step. On the other hand, the aluminum plate has a remarkably low softening temperature as compared with a steel plate or the like, so that the heating in the second step may significantly lower the strength. As described above, this reduction in strength causes a particular inconvenience when the coated plate is applied to an application requiring high pressure resistance, such as a beverage can. Therefore, the heating temperature in the second step is desirably as low as possible. However, if the heating temperature in the second step is low, the resin film cannot be sufficiently softened and melted as described above, and Is difficult to disintegrate, and as a result, it is difficult to obtain sufficient adhesion and good workability. As described above, ensuring a sufficient adhesive force and workability of the resin film and preventing the strength of the aluminum plate from decreasing are mutually contradictory in relation to the heating temperature in the second step. In order to overcome such contradictory objectives, the present inventors have conducted intensive experimental research, and as a result, as a heating method in the second step, it is possible to use both an induction heating method and an infrared heating method and switch at a predetermined temperature. I found it most appropriate.

In order to improve the adhesion, it is necessary to sufficiently melt and adhere the resin surface in contact with the aluminum plate. For that purpose, it is effective to cause the aluminum plate itself to generate heat by induction heating, and to melt the resin in contact with the aluminum plate from the inside by the heat and adhere the resin. In case of laminating work at high speed, heat conduction to the inside of the resin film is delayed, so that the resin surface in contact with the aluminum plate cannot be melted sufficiently because infrared heat or hot air heating inputs heat from the outside Is not preferred. Therefore, sufficient adhesion can be obtained by heating to the melting point Tm of the resin by induction heating that can be heated from the inside and that can be rapidly heated to reliably melt the resin.

In order to ensure sufficient workability, the resin film must be heated from the melting point Tm to a temperature of Tm + 30 ° C. to uniformly collapse the orientation of the entire resin film. However, in the induction heating method, the aluminum plate itself generates heat due to the induction current flowing through the aluminum plate, and the heat is conducted to the resin film, so that the temperature of the resin film tends to be lower than the temperature of the aluminum plate. If you try to raise the temperature of the film to a sufficiently high temperature, the temperature of the aluminum plate will also increase significantly,
As a result, there is a problem that the aluminum plate is significantly softened. To this end, after heating from the inside by induction heating, and after reaching the melting point Tm, heating from outside by infrared heating instead of induction heating.

In the infrared heating method, the energy radiated from the infrared irradiation heater is directly absorbed by the resin film covering the surface of the aluminum plate, so that the temperature of the resin film rises. Since infrared rays are not directly irradiated, the temperature rise is delayed. Here, in the case of infrared rays having a relatively long wavelength, the infrared rays may pass through the resin film and reach the aluminum plate surface, but even if the infrared rays reach the aluminum plate surface, the reflectance of the aluminum plate surface is low. Since the infrared rays are so high that the infrared rays are hardly absorbed, the infrared rays reaching the aluminum plate surface hardly contribute to the temperature rise of the aluminum plate. In addition, since the resin film generally has a low thermal conductivity, the heat conduction in the resin film is slow, and therefore, the temperature of the aluminum plate does not rapidly rise simultaneously with the temperature rise of the resin film due to the heat conduction. Therefore, these effects act synergistically, and according to the infrared heating method, as shown in FIG. 1B, the ultimate temperature of the aluminum plate present below the resin film is lower than the ultimate temperature of the resin film. Therefore, the resin film stays at a low temperature, and as a result, it is possible to sufficiently heat the resin film and to suppress a decrease in strength due to the softening of the aluminum plate.

The infrared heating method is also advantageous in that the resin film can be quickly and efficiently heated. In other words, infrared rays are a type of electromagnetic wave, and when the wavelength of the electromagnetic wave matches the absorption wavelength range of the object to be heated, energy is efficiently absorbed, molecular vibration becomes active, and the temperature rises rapidly. However, the wavelength of infrared rays is generally about 0.75 μm to 1000 μm, while most of resins generally used as resin films for coating have an absorption wavelength range of about 2 μm to 30 μm. By using a heater having a high infrared emissivity in the absorption wavelength region of the coating resin, the resin film can be efficiently and rapidly heated. However, heating from room temperature to the melting point Tm only by infrared heating requires a long furnace length, which is not only uneconomical but also requires a large installation space. Therefore, it is important to perform heating up to Tm by induction heating capable of more rapid heating, and then to use infrared heating in terms of speeding up work and increasing efficiency.

If the heating is switched from the induction heating to the infrared heating before reaching the melting point Tm, the heating is performed from the outside before the resin surface in contact with the aluminum plate is sufficiently softened and melted. Gets worse. If the resin surface in contact with the aluminum plate is heated by infrared rays until it melts in order to secure adhesion, the outer resin becomes T
m + 30 ° C., resulting in a problem that the film is roughened and whitened as described above. Alternatively, if the entire film is gradually heated so as to have substantially the same temperature, the furnace length becomes longer, which is problematic in terms of economy or equipment installation area.

As described above, first, the melting point T of the resin is determined by the induction heating method capable of rapid heating and heating from the inside of the resin.
m to melt the resin surface in contact with the aluminum plate to increase the adhesion, and then continue to exceed Tm to Tm +
Heating up to 30 ° C adopts an infrared heating method, which is effective to uniformly heat the resin and prevent softening of the aluminum plate by heating from the outside of the resin, thereby improving the workability of the resin film and preventing the softening of the aluminum plate. Thus, strong adhesion of the laminated resin can be ensured, workability is good, and a resin film-coated aluminum plate can be obtained if the strength of the aluminum plate is not reduced.

The heating method in the second step is as follows.
It is conceivable to apply a hot air heating method, but the hot air heating method is not desirable because rapid heating is difficult and a long furnace length is required. However, it is possible to simultaneously use the infrared heating method and the hot air heating method, and further rapid heating is expected. In addition, in the heating in the second step, the resin film needs to be softened and melted. Therefore, in the contact-type heat roll heating method, there is a disadvantage that the molten resin adheres to the roll. Accordingly, from these viewpoints, the induction heating method and the infrared heating method are most suitable as the heating method in the second step.

The cooling after heating in the second step is not particularly limited. However, in the case of slow cooling, unnecessary crystallization may be caused depending on the type of the film resin used.
Therefore, rapid cooling is generally preferred.

Next, a case where a thermoplastic resin film having two or more layers composed of two or more kinds of thermoplastic resins is used as a thermoplastic resin film laminated on one or both sides of an aluminum plate will be described.

When a resin film having a plurality of layers is used, the basic process and its operation are the same as those when the resin film having a single layer is used.
The heating temperature of the aluminum plate in the step and the heating temperature of the resin film in the second step need to be determined according to the resin of each layer constituting the resin film. That is, in the case of a resin film having a multilayer structure of two or more layers, a layer to be bonded to an aluminum plate (hereinafter referred to as an adhesive layer) and a layer exposed to the outer surface side in a final cover plate (hereinafter referred to as In the case of three or more layers, one or more intermediate layers are interposed between the adhesive layer and the outermost layer. Therefore, the heating temperatures in the first step and the second step need to be determined based on the glass transition temperature and the melting point of each of these layers.

Specifically, first, the heating temperature of the aluminum plate in the first step is a temperature not lower than the glass transition temperature of the resin forming the adhesive layer and lower than the melting point of the resin forming the outermost layer. It is necessary to That is, the temperature range is set so that the adhesive layer is softened and the outermost layer is not melted. As a result, the resin layer in contact with the aluminum plate is softened, and can be temporarily press-bonded to the aluminum plate by pressing with a laminating roll. If the heating temperature in the first step is lower than the glass transition temperature of the resin of the adhesive layer,
The resin of the adhesive layer may not be sufficiently softened, and the resin film may not be sufficiently adhered to the surface of the aluminum plate due to air entrainment or the like. On the other hand, if the heating temperature in the first step is equal to or higher than the melting point of the resin of the outermost layer, the resin of the outermost layer is melted and adheres to the laminating roll, and there is a possibility that the lamination cannot be performed smoothly.

In the first step in the case where the resin film having a plurality of layers is used, in order to increase the adhesion of the resin film to the aluminum plate as much as possible, the temperature of the adhesive layer reaches the melting point, and It is desirable that the resin in the layer be completely melted and pressed by a laminating roll. However, if the melting point of the resin of the outermost layer is equal to or lower than the melting point of the resin of the adhesive layer, the resin of the outermost layer is in a molten state while the resin of the adhesive layer is in a molten state. Disadvantageously adheres to the laminating roll. Therefore, it is desirable to use a resin film having a multilayer structure in which the melting point of the resin in the outermost layer is higher than the melting point of the resin in the adhesive layer.

When a resin film having a plurality of layers is used, the heating temperature in the second step is such that the melting point of the resin having the highest melting point among the resins of the plurality of layers constituting the resin film is Tm _1. For example, the temperature needs to be Tm ₁ or higher and Tm ₁ + 30 ° C. or lower. That is, the purpose of heating the resin film in the second step is not only to bond the resin film to the surface of the aluminum plate with a sufficient adhesive force as described above, but also to disintegrate the orientation of the crystallized resin film and obtain a favorable film. It is also important to provide good workability, and among the layers of the resin film having a multi-layer structure, the adhesion of the adhesive layer has progressed to some extent due to the heating in the first step, but has a melting point higher than that of the adhesive layer. Since the collapse of the orientation in the high layer is still insufficient, it is necessary to impart good workability by collapsing the orientation of these layers in the heating in the second step. Therefore, the heating temperature in the second step in the case of using a resin film having a plurality of layers is determined to be in the range of Tm ₁ or more and (Tm ₁ + 30 ° C.) based on the melting point Tm ₁ of the layer having the highest melting point. This is for melting the entire film.

The structure of the invention other than the above-mentioned heating temperature conditions when using a resin film having a plurality of layers is the same as that when using a resin film having a single layer as described above. Heating up to Tm ₂ is performed by induction heating, and heating up to Tm ₂ and below (Tm ₁ +30) ° C. is performed by infrared heating. By heating to the melting point Tm ₂ of the adhesive layer film and induction heating method, an aluminum plate by rapid heating to melt the adhesive layer, the effect of improving the adhesion. Also beyond Tm _{2 (Tm} 1 +30) ℃
Heating up to the following range is performed by the infrared heating method, so that heating from the outermost layer breaks the orientation of the film and imparts good workability, and also suppresses the temperature rise of the aluminum plate to prevent a decrease in strength. The effect to be obtained is obtained.

[0037]

EXAMPLE 1 An aluminum plate made of a JIS A3004 alloy having a thickness of 0.30 mm was subjected to a phosphoric acid chromate treatment of 20 mg / m ² as a base treatment to obtain a base treatment plate. The resin for the adhesive layer has a melting point of 215 ° C. and a glass transition temperature of 72.
° C polyester, melting point 26 as the resin of the outermost layer
0 ° C., using a polyester having a glass transition temperature of 75 ° C.,
A polyester film having a two-layer structure in which the thickness of the adhesive layer was 5 μm, the thickness of the outermost layer was 15 μm, and the total thickness was 20 μm, was laminated on both surfaces of the base treatment plate under the conditions shown in Table 1. In the present invention, an induction heating device and an infrared irradiation heater were used as heating means in the second step, and only an induction heating device was used as a comparative example. Here, as the infrared irradiation heater of the example of the present invention, a heater having a high infrared emissivity in a wavelength range of 2.5 to 25 μm was used. The strength (0.2% proof stress) of the finally obtained coated plate after lamination was examined. Further, workability and adhesion were examined by a cross-cut peel test of a plate rolled to 50% with a plate thickness including a laminate (hereinafter referred to as a 50% rolled plate). The workability was evaluated based on the presence or absence of cracks and surface roughness at the time of 50% rolling. In the cross-cut peeling test, 100 cross-cuts were cut in a 1 mm square with a cutter knife, and a peeling test was performed using Cellotape (registered trademark).
When the number of peeled grids was 10 or less, it was evaluated as ○, when it exceeded 10 and 50 or less, and when it exceeded 50, it was evaluated as ×. The results are also shown in Table 1.

[0038]

[Table 1]

From the above glass transition temperature and melting point of the resin,
The first step is within the scope of the present invention when heating to 72 to 260 ° C and the second step to induction heating to 215 ° C, and then heating to 260 to 290 ° C by infrared heating. In Production No. 1, sufficient workability and adhesion were not obtained because the heating temperature in the second step was low. Production numbers 2 and 3 are examples of the present invention, and showed good workability and adhesion. The production numbers 4, 5, and 6 are obtained by applying only the induction heating method as the heating means in the second step, while setting the heating temperature of each step to the same as that of the production numbers 1 to 3, respectively. At the temperature, the strength after final lamination is lower than in each of the present invention examples in which the induction heating method and the infrared heating method are used in combination. That is, the second
In step reachable temperature look at the case of 250 ° C., production number 1 of the present invention is the number 4 of the comparative example whereas a 276N / mm ² has a low value of 265N / mm ^2. Similarly, when the ultimate temperature is 265 ° C., Invention Example 2: 270 N / mm ²
Comparative Example 5: 260 N / mm ² , and ultimate temperature 2
In 80 ° C. Inventive Example 3: Comparative Example with respect to 260 N / mm ² 6: Both the 250 N / mm ² it can be seen that the strength is lowered. The production number 7 is a comparative example. Like the production number 2, the induction heating method and the infrared heating method are used in combination, and the adhesion is good. A decrease in strength is observed as compared with.
In the case of Production No. 8, since the heating temperature in the induction heating in the second step was too low and the heating was switched to infrared heating at a stage lower than the melting point of the adhesive layer, the result was slightly poor adhesion.

Example 2 The same base-treated plate as in Example 1 was laminated using a polyester film having the same two-layer structure as in Example 1 while changing only the heating conditions. Table 2 shows specific heating conditions in each step. The strength after lamination, and 5
Workability and adhesion were examined by a cross-cut peel test of a 0% rolled plate. The results are also shown in Table 2.

[0041]

[Table 2]

As shown in Table 2, the production number 9 is the same as that of the first embodiment.
This is a comparative example in which the heating temperature in the first step is lowered to 50 ° C. as compared with the inventive example of the production number 2 of the present invention. In this case, the strength after lamination is the same as that of the inventive example of the production number 2. ,
Since the heating temperature in the first step was low, the adhesive strength of the film was low, and peeling of more than 10 films occurred. Production number 10 is a comparative example in which the heating temperature in the second step is increased to 300 ° C. as compared with the inventive example of production number 3 in Example 1, and in this case, the heating temperature in the second step is high. Nevertheless, since the heating method is an infrared heating method,
The temperature rise of the aluminum plate was suppressed, and the strength after lamination was able to ensure 250 N / mm ² . However, the surface of the film was roughened by rolling, and peeling in the layer of the film, which was partially deteriorated in the cross-cut peeling test, occurred, resulting in loss of commercial value. Production number 11 is a comparative example in which the heating temperature in the second step is too low.
In this case, the formability and adhesion of the film were inferior, and as a result, cracking and peeling of the film were caused by rolling.

Example 3 Lamination was carried out in the same manner as in Example 1 except that a single-layer polyester film having a glass transition temperature of 72 ° C. and a melting point of 250 ° C. was used as the resin film. The specific heating conditions in each step are shown in Table 3, and the strength after lamination and the workability and adhesion were examined by a cross-cut peel test of a 50% rolled plate. The results are also shown in Table 3.

[0044]

[Table 3]

From the glass transition temperature and melting point of the above resin,
The first step is within the scope of the present invention when heating is performed at 72 to 250 ° C. and the second step is performed at up to 250 ° C. by induction heating, and then at 250 to 280 ° C. by infrared heating. In Table 3, production numbers 12 and 13 are examples of the present invention, and showed good workability and adhesion. Production numbers 14 and 15 were sufficient as the ultimate temperature in the second step, and the strength and workability after lamination were good. However, since the heating temperature by induction heating was lower than the melting point of the film, the adhesion was poor. The result was slightly inferior. Production numbers 16 and 17 correspond to 12, 1 and 12 of the present invention, respectively.
The heating temperature in Step 3 and each step are set to the same temperature, but only the induction heating method is applied as the heating means in the second step, instead of using both induction heating and infrared heating. Good workability and adhesion, but low strength (260 ° C
In the case of, number 12: 270 N / mm ² → number 16:26
No. 13: 265 at 3 N / mm ² and 270 ° C.
N / mm ² → number 17: 258N / mm ²⁾ has become.
No. 18 did not use induction heating in the heating of the second step,
Adhesion was slightly poor.

[0046]

According to the method of the present invention, an induction heating system and an infrared heating system are applied as heating means in the second step.
In addition, the heating temperature of the first step and the heating temperature of the second step are appropriately determined according to the melting point and the glass transition temperature of the laminated resin, and the temperature up to the melting point of the laminated resin is further heated by the induction heating method, and thereafter, the infrared heating method Because it is heated in
It is possible to obtain high adhesion and workability of the resin film while keeping the temperature attained by the aluminum plate low, suppressing the softening of the plate, and securing a sufficiently high strength after lamination. Therefore, according to the method of the present invention, it is possible to reliably and stably obtain a coated aluminum plate having high strength, good adhesion of the resin film and excellent workability. And especially in applications such as beverage cans where pressure resistance is required, even when using a resin film having a relatively high melting point exceeding 200 ° C., such as polyester,
The adhesiveness and workability of the resin film can be sufficiently ensured without reducing the strength of the aluminum plate, so that it is possible to sufficiently cope with thinning of beverage cans and the like.

[Brief description of the drawings]

FIG. 1A is a schematic view showing an example of a conceptual configuration of a situation in which a method of the present invention is performed, and FIG. 1B is an aluminum plate in each step corresponding to the configuration of FIG. FIG. 3 is a diagram illustrating temperature transition of a resin film.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 aluminum plate 3 supply reel 5 first heating means 7A, 7B laminating roll 9A, 9B thermoplastic resin film 11 second heating means (induction heating method) 12 third heating means (infrared heating method) 13 cooling device 14 winding Side reel

Continued on the front page F-term (reference) 4F100 AB10A AK01B AK01C AK17 AK41 AK46 BA02 BA03 BA06 BA10B BA10C EJ192 EJ432 EJ462 GB08 GB48 GB81 JB16B JB16C JK01 JK06 JL01 4F211 AA16 AA24 AA29 AD03 AD08 A08 AD03 A08 A08 TN16 TN26 TQ03 TQ10

Claims (2)

[Claims] 1. A method for producing a thermoplastic resin film-coated aluminum plate by laminating a thermoplastic resin film on an aluminum plate, wherein the aluminum plate is heated to a temperature above the glass transition temperature of the thermoplastic resin film and the melting point (T
m), a first step of laminating a thermoplastic resin film on at least one surface of the aluminum plate and pressing with a laminating roll to temporarily bond the aluminum sheet, and subsequent to the first step. And the temperature of the resin film is T
m and a temperature of (Tm + 30) ° C. or less. In the heating of the second step, if the heating temperature of the second step is T2, Tm
A method of producing an aluminum plate coated with a thermoplastic resin film, wherein heating up to Tm is performed by an induction heating method, and heating from Tm to T2 is performed by an infrared heating method. 2. A thermoplastic resin having two or more layers on an aluminum plate.
Laminate a multi-layer resin film composed of
Method for producing an aluminum plate coated with a plastic resin film
In, the aluminum plate to the thermoplastic resin film
Transition temperature of the resin in the layer in contact with the aluminum plate in
Degree or higher and the melting point of the resin in the outermost layer of the resin film
Heat to a temperature within the range of less than
Laminate by laminating resin film on at least one side
A first step of pressing with a roll and temporarily bonding,
Subsequent to the process, the resin of each layer constituting the resin film is
The melting point of the resin with the highest melting point (Tm₁) Against the tree
The temperature of the fat film is Tm ₁Above and (Tm₁+30
℃) From the second step of heating to be within the following range
And in the second step of heating, an aluminum plate
Melting point Tm of resin film of layer in contact with₂Heating until induction
Performed by heating method, Tm₂Beyond (Tm ₁+30
℃) Heating to below range is performed by infrared heating method.
Aluminum coated with thermoplastic resin film
Manufacturing method of the aluminum plate.