JPH0258094B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a method for manufacturing a metal plate coated with a polyester resin film, and more particularly, the present invention relates to a method for manufacturing a metal plate coated with a polyester resin film, and more particularly, a biaxially oriented polyethylene terephthalate resin film (hereinafter referred to as PET).
A PET-BO film is laminated onto a metal plate heated above the melting point of the PET-BO film (referred to as -BO film), and a polyester resin film-coated metal plate having a PET-BO resin layer on the upper layer and a non-oriented PET resin layer on the lower layer is manufactured. It is about the method. [Prior Art] Conventionally, a metal plate obtained by laminating a thermoplastic film onto a metal plate has been widely used in various fields such as electrical parts, furniture, storage cases, and interior and exterior building materials. Generally, the following method is well known as a method for continuously laminating a thermoplastic film on a metal plate. One method is to apply adhesive to the surface of the metal plate using a roll coater, etc., evaporate volatile substances such as solvents, then laminate and cool immediately, or further perform post-heat treatment and cool. It is. Another method is to introduce a polar group or the like into a thermoplastic resin in advance and laminate a thermoplastic resin film that can be thermally bonded. Examples include a vinyl chloride resin-coated steel plate made by laminating a vinyl chloride resin film to a steel plate using an adhesive, a polyolefin film laminated to a metal plate (Japanese Patent Application Laid-Open No. 141786-1986), and a copolymerized polyester film laminated to a metal plate. There are laminated ones (Japanese Patent Publication No. 57-23584) and ones in which a polyester film is laminated to a metal plate using an adhesive (Japanese Patent Publication No. 58-39448). [Problems to be solved by the invention] However, vinyl chloride resin-coated steel sheets have poor heat resistance and
The surface scratch resistance is not satisfactory,
Polyolefin resin-coated steel sheets have poor heat resistance and corrosion resistance, and copolymer polyester resin-coated steel sheets have the disadvantage of being high in cost and lacking in practicality. Furthermore, a metal plate in which a polyester film is laminated to a metal plate via an adhesive requires an adhesive coating process and oven equipment for evaporating volatile substances such as solvents, resulting in a significant decrease in workability. As described above, the thermoplastic resin-coated metal plates conventionally invented have advantages and disadvantages, and none of them are satisfactory. [Means for Solving the Problems] Against this background, the present invention focuses on a PET-BO film that has excellent properties such as corrosion resistance, processability, electrical insulation, heat resistance, and chemical resistance. PET-
The object of this invention is to provide a metal plate coated with a polyester resin film in which a BO film is laminated to a metal plate without using an adhesive or the like, and has the following characteristics and effects. That is, the method of the present invention is characterized by laminating the PET-BO film continuously and at high speed on one or both sides of a metal plate heated to the melting point of the PET-BO film or higher, and then rapidly cooling the film. In the metal plate coated with a polyester resin film obtained by the method of the present invention, the biaxially oriented crystals are broken only near the interface with the metal plate, resulting in a thin non-oriented and amorphous state, and the surface layer is biaxially oriented. It has a so-called two-layer structure in which a crystal layer remains, and has excellent properties such as processing adhesion, processing corrosion resistance, and chemical resistance. In general, PET-BO film has oriented crystals and has excellent barrier properties against moisture and various ion permeability, and has been used in various packaging material fields. In addition, it has extremely excellent mechanical properties and heat resistance, so it has been widely used in fields such as magnetic tape and electrical insulation, but because it has highly oriented crystals, it has no adhesion to adherends without an adhesive. It had the disadvantage of not having. on the other hand
A non-oriented, amorphous state obtained by heating PET-BO film above its melting point and rapidly cooling it.
PET resin has such excellent adhesive strength that it is used as an adhesive between metal plates, as shown in Japanese Patent Publication No. 49-34180. However, non-oriented, amorphous PET resin has the drawbacks of significantly lowering its barrier properties against moisture and various ion permeability, and also significantly lowering its mechanical strength. As described above, PET resin has properties that vary greatly depending on whether or not it has oriented crystals. The reason why the polyester resin film-coated metal plate obtained by the method of the present invention has excellent processing adhesion and processing corrosion resistance is that, as already mentioned, the surface in contact with the metal plate has a non-oriented structure with excellent adhesive strength. amorphous
The PET resin layer is thin and uniformly formed.
On top of the unoriented, amorphous PET resin layer, there is a PET-BO resin layer that has barrier properties against water and various ions and has excellent mechanical properties, and the two are well balanced. it is conceivable that. The polyester resin film-coated metal plate according to the present invention has many excellent properties such as processing adhesion, processing corrosion resistance, heat resistance, and electrical insulation, so it can be used for can lids, squeezed cans, double-drawn cans, etc. It can be used not only as a material for cans, but also as a component for electrical products, taking advantage of the electrical insulation and heat resistance properties of PET resin. Hereinafter, the content of the present invention will be explained in detail.
First, PET-BO film is a polycondensate of polyethylene glycol and terephthalic acid, which is formed into a film after a known extrusion process, then stretched in both the vertical and horizontal directions, and then subjected to a heat-setting process. As for the film thickness,
Although not particularly limited, it is preferably 5 to 300 μm, and when the film thickness is 5 μm or less,
Lamination workability is significantly reduced, and after lamination, it is extremely difficult to maintain a good balance between the non-oriented, amorphous PET resin layer and the biaxially oriented PET resin layer. On the other hand, when the thickness is 300 μm or more, properties such as processing corrosion resistance and electrical insulation properties are ensured, but the economic efficiency is inferior. These films can be treated with heat, light stabilizers, antioxidants,
Additives such as pigments and antistatic agents may be added, or activation treatment such as corona discharge treatment may be performed to improve adhesion. Next, the metal plate used in the present invention is as follows:
Examples include sheet-like and coil-like steel plates, steel foils, iron foils and aluminum plates, aluminum foils, and surface-treated metal plates. In particular, electrolytic chromic acid treated steel sheets with a two-layer structure of metallic chromium in the lower layer and chromium hydrated oxide in the upper layer, ultra-thin tin-plated steel sheets, ultra-thin iron-tin alloy coated steel sheets, ultra-thin chromium-plated steel sheets, nickel-plated steel sheets. Steel sheets, copper-plated steel sheets, galvanized steel sheets, chromium hydrated oxide-coated steel sheets, organic-treated steel sheets with polar groups such as carboxyl groups or chelate structures, or phosphate-treated, chromate-treated, or organic-treated steel sheets as described above. This aluminum plate has particularly excellent adhesive strength with the PET-BO film, and is therefore suitable as the metal plate used in the present invention. Furthermore, the following two-layer and three-layer coated steel sheets, alloy plated and composite plated steel plates are also suitable. Examples include chromate-treated, phosphate-treated, chromium-chromate-treated or organic-treated steel sheets coated with these metals, double- or triple-layer plating of these metals, and steel sheets coated with alloys such as nickel-tin. Examples include composite galvanized steel sheets containing a small amount of at least one of nickel, cobalt, iron, chromium, and molybdenum in the form of a metal or a compound. Next, the temperature of the metal plate immediately before laminating the PET-BO film, which is one of the important factors in the present invention, is the melting point (Tm) of the PET-BO film.
It is necessary to keep the temperature at ~(Tm+100)°C. The melting point (Tm) here is determined from the endothermic peak of a differential scanning calorimeter (DSC) at a heating rate of 10°C/min, and Tm is the point indicating the maximum depth of the endothermic peak. Call me. The temperature of the metal plate is Tm
At the following temperatures, laminated PET-BO
PET-BO on the side of the film in contact with the metal plate
The film is not sufficiently oriented or amorphous, and sufficient adhesion cannot be obtained. On the other hand, if the metal plate is heated above (Tm+100)℃, the laminated PET−
Most of the BO film becomes non-oriented and amorphous, resulting in a decline in properties such as processing corrosion resistance and electrical insulation. Furthermore, when the temperature reaches (Tm+100)°C or higher, the shape (flatness) of the metal plate tends to collapse. Next, the surface temperature of the laminating roll when laminating the PET-BO film on the metal plate is also an important factor in the present invention. That is, the formation of the two-layer structure of the PET-BO film of the present invention is uniquely determined during the very short time that the PET-BO film is in contact with the laminating roll nip.
That is, when a PET-BO film is laminated onto a metal plate heated to a high temperature, a temperature gradient occurs in the PET-BO film, with the metal plate side being high temperature and the lamination roll side being low temperature. While passing through the laminating roll, a temperature gradient continues to occur in the PET film, and the temperature of the metal plate decreases due to the heat of fusion of the oriented crystals of the PET film and heat absorption from the laminating roll. Then, the moment the laminated metal plate comes out of the nip of the laminating roll,
There is no temperature gradient in the PET film, which matches the temperature of the metal plate. Therefore, it is necessary to lower the temperature of the metal plate to below the biaxially oriented fracture initiation temperature (To) of the PET-BO film while passing through the laminating rolls. In order to create such conditions,
The surface temperature of the laminating roll is a particularly important factor. In other words, the surface temperature of the laminating roll is
It is necessary to control the temperature at 30-180°C, more preferably at 50-150°C. When the surface temperature of the laminating roll exceeds 180°C, when a PET-BO film is laminated onto a metal plate, the biaxially oriented crystals will collapse across the gold layer in the film, although this will vary depending on the thickness of the PET-BO film. , processing corrosion resistance, electrical insulation properties, etc. deteriorate. On the other hand, if you try to lower the surface temperature of the laminating roll to 30℃ or less,
It is necessary to attach a special cooling device such as external cooling to the laminating roll itself, which is undesirable because the equipment becomes large-scale. Controlling the surface temperature of the laminating roll becomes more important as the laminating speed increases. As for the material of the laminating roll, any of chrome-plated rolls, ceramic rolls, and rubber rolls can be used, but rubber rolls are preferable in order to perform high-speed and beautiful lamination. The rubber material of the rubber roll is not particularly limited, but a silicone roll with excellent thermal conductivity and heat resistance is preferred. Next, the cooling conditions after laminating the PET-BO film on the metal plate are also important factors in the present invention. In other words, it is important to rapidly cool the polyester resin film-coated metal plate to below 100°C within 10 seconds after lamination.If the temperature is kept at 100°C or higher for a long time, the metal plate formed at the interface of the metal plate during lamination may The oriented and amorphous PET resin layer turns into coarse spherulites, resulting in a significant decrease in processing adhesion and processing corrosion resistance. The method of rapid cooling is not particularly limited, but preferred are an underwater immersion method, a water spray method, and the like. Next, methods for heating the metal plate include the known hot air heat transfer method, resistance heating method, induction heating method,
Examples include a heat roll heat transfer method, and although it is not particularly limited, the heat roll heat transfer method is preferable in consideration of equipment cost, simplification of equipment, and short-time temperature rising characteristics. Next, the amount of non-oriented, amorphous PET resin produced after laminating the PET-BO film to the metal plate is also an important factor, and the thickness of the PET-BO resin should be 15 to 95% of the total PET resin layer. is important. PET-
If the thickness of the BO resin layer is 95% or more of the total PET resin layer, the processing adhesion will be poor and it will be easy to peel off, especially when deep drawing processing is performed. On the other hand, when the content is less than 15%, workability, corrosion resistance, electrical insulation properties, etc. decrease significantly. As described above, the remaining amount of biaxially oriented crystals is an important factor, and methods for determining the remaining amount of biaxially oriented crystals include the birefringence method, density method, and X-ray diffraction method. According to the law, it is required as follows. (1) Measure the X-ray diffraction intensity of the PET-BO film before lamination and the PET film after lamination in the range of 2θ = 20 to 30°. (2) Connect the X-ray diffraction intensity curves at 2θ=20° and 2θ=30° with a straight line to form the baseline. (3) Measure the sharp peak height that appears around 2θ = 26° from the baseline. (4) When the peak height of the film before lamination is Ia and the peak height of the film after lamination is Ib, Ib/Ia×100 is the remaining amount of biaxially oriented crystals. [Example] Hereinafter, a detailed explanation will be given in Examples. Example 1 A cold-rolled steel plate with a thickness of 0.23 mm was electrolytically degreased in 70 g/sodium hydroxide solution, pickled with 100 g/sulfuric acid solution, washed with water, and then treated with a solution of chromic anhydride 30 g/sodium fluoride/1.5 g/sodium fluoride solution. Among them, the current density
A cathodic electrolytic treatment was performed under the conditions of 20 A/dm ² and an electrolyte temperature of 30° C., followed by washing with hot water of 80° C. and drying. A 16 μm thick PET-BO film (trade name: Lumirror, manufactured by Toray Industries, Inc.) was laminated continuously on both sides of the electrolytically chromic acid treated steel plate having a width of 300 mm as described above under the following conditions. Heating method for steel strip strips...Temperature of steel plate just before heat roll heating lamination...290℃ Lamination roll...Silicon roll Surface temperature of lamination roll...max 90℃ Time until the laminated steel plate is cooled to below 100℃ ...2 seconds The amount of biaxially oriented crystals of the obtained polyester resin film-coated steel plate was calculated by X-ray diffraction method under the following conditions. Diffraction conditions Target: Cu Tube voltage 40KV Tube current 20mA Method for calculating the amount of biaxial orientation (1) The film before lamination and the coated metal plate after lamination were each measured in the range of 2θ=20 to 30°. (2) The X-ray diffraction intensity curves at 2θ=20° and 2θ=30° were connected with a straight line to form a baseline. (3) The peak height of the sharp peak that appears around 2θ = 26° was measured from the baseline. (4) The peak height of the film before lamination is Ia,
When the peak height of the film after lamination is Ib, Ib/Ia×100 is defined as the remaining amount of biaxially oriented crystals. Example 2 A cold-rolled steel sheet similar to that in Example 1 was pretreated in the same manner as in Example 1, and then treated with 25 g of tin sulfate, 15 g of phenolsulfonic acid (60% aqueous solution), and ethoxylated α-naphtholsulfur. Using an electrolyte containing 2 g of fonic acid, a current density of 20 A/dm ² and an electrolyte temperature of 40°C.
Tin plating with a tin concentration of 0.3g/m ² was carried out under the conditions of
Dry. A PET-BO film (trade name: Lumirror, manufactured by Toray Industries, Inc.) having a thickness of 38 μm was laminated continuously on both sides of the tin-plated steel strip having a width of 300 mm under the following conditions. Heating method for steel strip strips...Temperature of steel strip just before heating with heat roll and lamination...280℃ Lamination roll...Silicon roll Surface temperature of lamination roll...160℃ Time until laminated steel plates are cooled to below 100℃ ...3 seconds The amount of biaxially oriented crystals in the obtained polyester resin film-coated steel sheet was determined by X-ray diffraction in the same manner as in Example 1. Example 3 A cold-rolled steel sheet similar to that in Example 1 was pretreated in the same manner as in Example 1, and then treated with nickel chloride (hexahydrate) 40
Nickel plating of 0.6 g/m 2 was performed using ^a Watts bath consisting of 250 g/g of nickel sulfate (hexahydrate) and 40 g of boric acid at a current density of 10 A/dm ² and a bath temperature of 45°C. provided. After washing with water, in a solution of 30 g of sodium dichromate, at a current density of 10 A/dm ² ,
Chromate treatment was performed at an electrolysis temperature of 45°C, washed with water, and dried. A PET-BO film (trade name: Lumirror, manufactured by Toray Industries, Inc.) having a thickness of 188 μm was continuously laminated on both sides of the nickel-plated steel strip having a width of 300 mm under the following conditions. Heating method for steel strip strips...Temperature of steel strip just before heat roll heating and lamination...350℃ Laminating roll...Silicon roll Surface temperature of laminating roll...120℃ Time until the laminated steel plate is cooled to below 100℃ ...8 seconds The amount of biaxially oriented crystals in the obtained polyester resin film-coated steel sheet was determined by X-ray diffraction in the same manner as in Example 1. Example 4 An aluminum plate with a thickness of 0.30 mm was cathodic electrolytically degreased in a 30 g/soda carbonate solution, washed with water, and then treated with phosphoric acid.
After immersion treatment at a bath temperature of 25° C. using a bath containing 60 g of chromic acid, 10 g of sodium fluoride, and 5 g of sodium fluoride, the sample was washed with water and dried. A 75 μm thick PET-BO film (product: Diafoil, manufactured by Diafoil Co., Ltd.) was continuously laminated on both sides of this 300 mm wide strip aluminum plate under the following conditions. Heating method for strip aluminum plate...Temperature of aluminum plate just before heat roll heating lamination...300
℃ Laminating roll...Silicon roll Laminating roll surface temperature...40℃ Time until the laminated aluminum plate is cooled to below 100℃...1 second Biaxially oriented crystals of the obtained polyester resin film-coated aluminum plate The amount was determined by X-ray diffraction in the same manner as in Example 1. Example 5 An aluminum plate with a thickness of 0.30 mm was cathodic electrolytically degreased in a 30 g sodium carbonate solution, and after washing with water, the
Chromate treatment was performed using a sodium dichromate solution, washed with water, and dried. A 25μm thick PET-BO film (product name: Diafoil: manufactured by Diafoil Co., Ltd.) is placed on this 300mm wide strip aluminum plate.
were continuously laminated on both sides under the following conditions. Heating method for strip aluminum plate...Temperature of aluminum plate just before heat roll heating lamination...270
°C Laminating roll...Silicon roll Surface temperature of the laminating roll...120°C Time until the laminated aluminum plate is cooled to below 100°C...5 seconds Biaxially oriented crystals of the obtained polyester resin film-coated aluminum plate The amount was determined by X-ray diffraction in the same manner as in Example 1. Comparative Example 1 Using the same PET-BO film and steel plate as in Example 1, lamination was carried out under the same conditions except for the surface temperature of the laminating roll. Surface temperature of laminating roll...max 210°C The amount of biaxially oriented crystals in the obtained polyester resin film coated steel plate was determined by X-ray diffraction in the same manner as in Example 1. Comparative Example 2 Using the same PET-BO film and steel plate as in Example 1, lamination was performed under the same conditions except for the cooling conditions after lamination. Time required for the laminated steel plate to cool to below 100°C...25 seconds The amount of biaxially oriented crystals in the obtained polyester resin film coated steel plate was determined by X-ray diffraction using the same method as in Example 1. . Comparative Example 3 Using the same aluminum plate and PET-BO film as in Example 4, lamination was performed under the same conditions except for the lamination temperature. Temperature of aluminum plate just before lamination...255
C. The amount of biaxially oriented crystals in the obtained aluminum plate coated with a polyester resin film was determined by X-ray diffraction in the same manner as in Example 1. Comparative Example 4 Using the same aluminum plate and PET-BO film as in Example 5, lamination was performed under the same conditions except for the lamination temperature. Temperature of aluminum plate just before lamination...405
C. The amount of biaxially oriented crystals in the obtained aluminum plate coated with a polyester resin film was determined by X-ray diffraction in the same manner as in Example 1. The polyester resin film-coated metal plate was evaluated by the following test method, and the results are shown in Table 1. (1) Measurement of the amount of plating on the metal plate The amount of plating and film amount was measured using a fluorescent X-ray method. (2) Adhesive strength between metal plate and polyester resin film The diameter of the metal plate coated with polyester resin film
After punching out an 80 mm disc and drawing it into a cylindrical cup at a drawing ratio of 2.0, the polyester resin film on the body was subjected to hot water treatment for 1 hour in boiling water. It was divided into 5 grades, with 5 points being rated as 1 point and 1 point being total peeling. (3) Processing corrosion resistance 50 ml of citric acid adjusted to pH 2.2 was placed in the cylindrical cup described in item (2) above, and the cup was left at 55°C for 30 days, and eluted iron or eluted aluminum was measured. Also, put 3% NaCl in the same cup and heat it at 55°C.
After being left for 30 days, the corrosion status was investigated by visual observation.

【table】

〔Effect of the invention〕

PET− on one or both sides thus obtained.
Metal plates laminated with BO film have excellent processing corrosion resistance and processing adhesion, so they can be used in a wide range of applications such as container materials, building materials, and electrical equipment components.

Claims (1)

[Claims] 1 When laminating PET-BO film on one or both sides of a metal plate heated to the melting point (Tm) of biaxially oriented polyethylene terephthalate resin (Tm) to (Tm + 100℃), the surface temperature of the laminating roll is controlled at 30 to 180℃. After laminating with a laminating roll, the film is cooled to 100°C or less within 10 seconds, and the upper layer has a PET-BO resin layer, the lower layer has a non-oriented PET resin layer, and the thickness of the PET-BO resin layer is completely covered. A method for producing a metal plate coated with a polyester resin film, characterized in that the PET resin layer is 15 to 95%.