JPS5892520A - Preparation of resin film covered metal plate - Google Patents

Abstract

PURPOSE:To obtain a resin film covered metal plate which is excellent in adhesiveness between base materials and useful as a material for can making by such an arrangement wherein a strip of metal plate is covered with a polyester film having a metallic thin membrane, and then the surface of contact between said thin membrane and said film is heated at a specified temperature. CONSTITUTION:A film of polyester C (most preferably such one of which melting point is 130-300 deg.C) having a metallic thin membrane B (for instance: single thin membrane of Al, etc.) is caused to cover a strip of metal plate A which is heated up to a temperature of a value, the melting point of ingredient C, Tm- Tm+130 deg.C, and then the contact surface between the ingredient B and C is heated up to a temperature of the melting point of ingredient C, Tm-Tm+ 130 deg.C, to cause the ingredient B and the ingredient A and C to adhere to each other, and by this, the intended metal plate is obtained. As a heating method, high frequency heating, etc. are preferable. EFFECT:The product is excellent in corrosion resistibility, appearance and mechanical properties.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a metal plate coated with a resin film, and more specifically, the present invention relates to a method for manufacturing a metal plate coated with a resin film, and more particularly, a metal plate obtained by coating a metal plate with a polyester resin film having a metal thin film, a metal plate coated with a metal thin film, and a polyester resin. The present invention relates to a method for manufacturing a resin film-coated metal plate that has extremely good adhesive properties.

Traditionally, the main material for cans has been tin, but with the depletion of tin and the soaring prices, and changes in the content of cans, there has been a growing trend for tin cans to be coated on the inside. On the other hand, due to the rapid increase in demand for beverage cans, electrolytic chromic acid treated steel sheets (Tin Free 5teel...
...The use of TFS (hereinafter referred to as TFS) has increased and achieved considerable results, and from the comparison with the tinplate mentioned above, TFS
has become highly valued as a material for cans. However, there are still some aspects of TFS that are not as good as tinplate in terms of its properties (mainly aesthetics and corrosion resistance), and attempts have been made to cover it with painting, but there are limits to the improvement of corrosion resistance by painting.

On the other hand, attempts were made to improve the coating method (coil-shaped precoating) with the aim of reducing costs, but these efforts resulted in limited paint types (fast-curing paints) and high equipment costs (4 to 5 coats of sheet paint).
The reality is that LA has hardly been put into practical use due to reasons such as low productivity and low productivity.

On the other hand, a resin film-coated metal plate is manufactured by applying an adhesive to the metal surface, heating it in an oven with a long distance capacity (to about 20°C), laminating a resin film, and cooling it. Alternatively, a method has generally been adopted in which a post-heating treatment is further performed and then cooled. However, such a method is difficult to install a long oven.
There are limitations due to equipment problems, and as a result, productivity is extremely low (speed: 20 to 30 m/min), production costs are high, and performance is not sufficient.

In addition, looking at the history of demand for resin film-coated metal sheets in terms of applications, they have mainly been used for interior and exterior building materials, electrical parts, storage case materials, vehicle interior materials, furniture, and household goods materials, etc., but recently, It has become possible to use it as a material for containers, especially cans. However, if a thin Sn-plated plate or a chrome-plated plate is used as a metal plate, the aesthetics and corrosion resistance will be poor.
In addition, the current situation is that sufficient features of resin film-coated metal plates have not been discussed, such as the fact that the use of thick Sn-plated metal plates would result in high costs.

From this perspective, the present invention focuses on its usefulness as a material for cans, and also improves corrosion resistance, aesthetics, and 81! The purpose is to provide a resin film-coated metal plate with mechanical properties, and has the following features and effects. In the method for producing a film-coated metal plate that covers the surface, after coating a strip-shaped base metal plate with a polyester resin film having a metal thin film on at least one side, preheating the metal plate or, if necessary, post-heating the coated plate. The present invention aims to provide a resin film-coated metal plate that can withstand the molding process of cans by heating the interface between the metal thin film and the polyester resin to a temperature higher than the melting point of the polyester resin, thereby strengthening the adhesion between the metal thin film and the polyester resin. This is the purpose.

Hereinafter, the content of the present invention will be explained in detail.

First, the metal plates used in the method of the present invention are as follows: A: Mild steel plate (including rolled foil) or electroformed iron foil; B: Sn, Cr, Zn, Cu,
A single substance whose main component is one or more of Aji or Ni.

Multilayer or alloy plated metal plate, C: above A,
Examples include a metal plate whose surface has been subjected to electrolytic chromic acid treatment, immersion chromic acid treatment, or phosphate treatment.

Next, we will discuss polyester resin.

As the coating material used in the present invention, polyester resins are preferable in consideration of adhesion to metal plates and anticorrosion properties, and among them, the following saturated polycarboxylic acids and saturated polyhydric alcohols, namely saturated polycarboxylic acids: phthalic acid, Isophthalic acid.

Terephthalic acid, cobalic acid, azelaic acid, adipic acid, sepacic acid, dodecanedioic acid, diphenylcarboxylic acid, 2.6 naphthalene dicarboxylic acid, 1.4 cyclohexane dicarboxylic acid, trimethic anhydride.

Saturated polyhydric alcohol: ethylene glycol.

1,4 butanediol, 1.5bentanediol.

1,6 hexanediol, propylene glycol.

polytetramethylene glycol, diethylene glycol, polyethylene glycol, triethylene glycol,
Neopentyl glycol.

1,4 cyclohexane dimetatool, trimethylolpropane, pentaerythritol.

It is preferable that the synthesized resin has a melting point of 130 to 300°C. If the melting point is below 130°C, film peeling will occur during heat sterilization.
Productivity is poor at temperatures above 300°C. Note that the melting point referred to here is determined from the endothermic peak by differential thermal analysis. When the resin is a mixture of two or more types and has two or more endothermic peaks, the endothermic peak resulting from the main component of the resin is taken as the melting point. In addition, the thickness of the film formed from the resin is 3 to 30% considering corrosion resistance and economical efficiency.
Preferably, it is 50 μm.

Next, we will discuss metal thin films aimed at providing aesthetic appeal and improving corrosion resistance.

The metal thin film used in the method of the present invention is shown below.

Metal thin film of either E or F, that is, D: Sn,
Single metal thin film of Cr, Zn, Cu, Ni, Kl, E: Multilayer thin film of two or more metals listed above, F: Composite thin film containing one or more of the metals listed above as a main component. In consideration of aesthetics and economy, the thickness of the metal thin film is preferably 50 to 2000X.

If the thickness of the metal thin film is less than 50X, sufficient improvement in aesthetics cannot be achieved, and if it is more than 2000X, it is less economical.
Also, I cannot see much of an effect by increasing zoooX or higher. The method for forming the metal thin film on the polyester resin film is not particularly limited, and methods such as vacuum evaporation and electroless plating, or a combination of these methods may be used.

Next, a method of coating the metal plate with the polyester resin film having the metal thin film thus obtained will be described.

First, in order to coat a metal plate with the polyester resin film, it is necessary to heat the metal plate to a temperature corresponding to the bonding conditions of the polyester resin.

In other words, the temperature of the metal plate is set to the melting point (Tm) of the polyester resin.
) to Tm+130°C. If the temperature of the metal plate is below Tm, the coverage will be poor.1. Also Tm+130℃
The above heating of the metal plate is unnecessary and is not preferable because it causes severe thermal deterioration of the polyester resin. Next, in order to withstand the can molding process, not only the metal plate but also the metal thin film and polyester resin must be firmly bonded. To achieve this objective, the temperature at the interface between the metal thin film and the polyester resin must be adjusted to the melting point of the polyester resin (
Tm) to Tm+130°C. If the interface temperature is below Tm, the adhesion will be poor, and if it is above Tm + 130°C, it is unnecessary and undesirable as it will cause deterioration of the polyester resin and significant oxidation of the metal thin film.

Further, after coating the metal plate with the polyester resin film, post-heating may be performed, but the post-heating time is preferably within 30 seconds in consideration of deterioration of the polyester resin. In addition, heating methods include oven heating, infrared heating, and high frequency heating.

A method such as resistance heating or a combination thereof may be used, but in consideration of productivity, a heating method using high frequency heating and resistance heating is preferable. Further, in the present invention, it is preferable that the polyester resin film is temporarily coated and then rapidly cooled after heating. Slow cooling progresses oxidative decomposition and excessive crystallization of the polyester resin, resulting in poor processability and adhesion of the polyester resin film coating II&. As for the cooling method, water cooling, liquid nitrogen cooling, or other methods may be used, but it is preferable to cool the base film to below the melting point within 1 second in a water bath at 0 to 90'C.

As described above, since the resin film-coated steel sheet manufactured by the method of the present invention has a base material of a metal plate,
It is easy to heat the contact interface between the metal thin film and the polyester resin to a temperature higher than the melting point of the polyester resin, and according to the present invention, the metal thin film and the resin film can be firmly bonded.

If there is no metal plate, there are problems such as poor adhesion between the metal thin film and polyester resin (even if the film is heat-treated with an adhesive, the shape of the base film will deteriorate, etc.). For example, the resin film with
Polyester films deposited with aluminum have insufficient adhesion between the aluminum thin film layer and the polyester film layer, and only the method of the present invention can improve the adhesion between the metal thin film and polyester.

Furthermore, unlike a simple combination of a resin film and a metal thin film, the resin film-coated metal plate obtained by the present invention can be plastic-processed and has a wide range of applications as a material for cans.

Examples will be shown below to explain the effects.

Example 1 One side of a metal plate with nickel plating (C2, O9/d) on both sides of a mild steel plate (plate width: 1 m, plate thickness: 0.23 fi),
Polyester resin film with Ae thin film (60'OX) (manufactured by Toyobo Co., Ltd., product name: E-5000, 20 μm)
After coating (temperature of metal plate at the time of coating: 290° C., lamination speed: 80 m/min), soaking was performed for 10 seconds and then quenched by immersion in water to obtain a resin film-coated metal plate.

10% resin film coated metal plate made under the above conditions
After stretching, 180° peel test (tensile speed: 100 m/
As a result, the resin film was broken and could not be peeled off, and the adhesiveness was good. In addition, a can (inner surface: surface covered with resin film) obtained by deep drawing a resin film-coated metal plate (drawing ratio: 1.7) was filled with a citric acid aqueous solution adjusted to pH 20, and then placed in an atmosphere at 55°C for one month. As a result of standing, the amount of iron ions eluted into the contents was 0.1 ppm or less. Moreover, the appearance of the resin film-coated metal plate exhibits the appearance of A6 even after deep drawing, and is excellent in appearance.

Example 2 Sn and Ni composite plating (Sn: 0.2?/w) on both sides of a mild steel plate (width: 208m, thickness: 0.32fi)
l, Ni: 0.1f/G) on both sides of the metal plate.
Polyester resin film with n thin film (1200X) (manufactured by Toyobo Co., Ltd., product name: Pylon GM800.15
After coating (temperature of metal plate at the time of coating = 270°C, lamination speed: 100.m/min,), 280
After heating in an atmosphere of ℃ for 5 seconds, quenching with water spray,
A metal plate coated with a resin film was obtained.

10% resin film coated metal plate made under the above conditions
After stretching, 180° peel test (tensile speed: 100 wx
/ min,), the resin film broke,
It could not be peeled off and had good adhesion. In addition, cans obtained by deep drawing (drawing ratio: 2.0) resin film-coated metal plates (
After filling the inner surface (resin film coated surface) with a phosphoric acid aqueous solution adjusted to pH 3.0 and leaving it in an atmosphere at 55.degree. C. for one month, the amount of iron ions eluted into the contents was 0.1 ppm or less. Ta. Further, the appearance of the resin film-coated metal plate exhibits a Sn appearance even after deep drawing, and is excellent in aesthetic appearance.

Example 3 Sr − on iron electroformed foil (plate width: 1 m, thickness: 30 μm)
After coating a polyester resin film (manufactured by ICI, trade name: Melinex #850.30μm) having a Ni thin film (average thickness of Sn: 3ooXyN; average thickness: 200X) on polyethylene terephthalate (the thickness of the metal plate at the time of coating) Temperature: 300℃, lamination speed: 120m
/min, ), and was rapidly cooled by immersion in water to obtain a resin film-coated metal plate.

10% resin film coated metal plate made under the above conditions
After stretching, 180° peel test (tensile speed: 100 tx
/ min,), the resin film broke,
It could not be peeled off and had good adhesion. Further, a can obtained by deep drawing a resin film-coated metal plate (drawing ratio: 1.5) was filled with a phosphoric acid aqueous solution adjusted to pH 3.0, and then heated at 55°C.
As a result of being left in the atmosphere for one month, the amount of iron ions eluted into the contents was 0.1 ppm or less. Further, the resin film-coated metal plate has a 5n-Ni metallic luster even after deep drawing, and is excellent in aesthetic appearance.

Comparative Example 1 - A polyester resin film (manufactured by Toyobo Co., Ltd., trade name: E-5000, 2) was coated on one side of the same plated metal plate as in Example 1.
After coating (temperature of metal plate at the time of coating: 290℃,
After soaking for 10 seconds at a lamination speed of 80 m/min, the sample was rapidly cooled by immersion in water to obtain a resin film-coated metal plate.

After filling a can (inner surface: resin film coated surface) obtained by deep drawing the resin film coated metal plate created under the above conditions (drawing ratio: 1.7) with a citric acid aqueous solution adjusted to pH 2.0, After being left in an atmosphere at 55°C for one month, the amount of iron ions eluted into the contents was 0.6 ppm'. Moreover, the aesthetic appearance is inferior to that of the resin film-coated metal plate of Example 1.

' Comparative Example 2 Iron electroformed foil same as Example 3 (plate width: 1 m, thickness 130μ
m) was coated with a polyester film having the same 5n-I-Ni thin film as in Example 3 (temperature of the metal plate at the time of coating:
230℃, lamination speed: 120m/min, ),
It was quenched by immersion in water to obtain a resin film-coated metal plate.

The resin film coated metal plate made under the above conditions was 109
6 After stretching, 180° peel test (tensile speed: 100 ws
/min,), the resin film was completely peeled off. Further, when the resin film-coated metal plate was deep drawn (drawing ratio: 1.5), significant peeling of the 5n-Ni thin film from the polyester resin was observed.

Claims (1)

[Scope of Claims] (1) In a method for producing a resin film-coated metal plate in which a belt-shaped metal plate is continuously coated with a polyester resin film having a metal thin film, the contact interface between the metal thin film and the polyester resin film is provided. and a method for producing a resin film-coated metal plate, in which the temperature of the metal plate is heated to the melting point (T, m) of the film to Tm+130°C, and the polyester resin is bonded to the metal plate and the metal thin film. (2) The metal plate is one of the following metal plates: A: Mild steel plate (including rolled foil) or electroformed iron foil; B: Sn, Cr, Zn, Cu on the surface of A above. A single 1. A multilayer or alloy-plated metal plate; C: A metal plate whose surfaces of A and B have been subjected to electrolytic chromic acid treatment, immersion chromic acid treatment, or phosphate treatment. A method for producing a resin film-coated metal plate according to item 1. (3) The metal thin film is one of the following metal thin films 'E and F, namely D: Sn, Cr, Zn, Cu, A7! ,
Claim 1, which is a single metal thin film of Ni, E: a multilayer thin film of two or more metals listed above, F: a composite thin film containing one or more of the metals listed above as a main component The method for producing the resin film-coated metal plate described above. (4) The method for manufacturing a resin film-coated metal plate according to claim 1, wherein the metal thin film has a thickness of 50 to 2'00OX. (5) Melting point of polyester resin is 130-300℃
And, the resin has the following saturated polycarboxylic acids and saturation ratios (hydric alcohols), ie, saturated polycarboxylic acids: phthalic acid, isophthalic acid. Terephthalic acid, succinic acid, azelaic acid, adipic acid,
Sebacic acid, dodecanedioic acid, diphenylcarboxylic acid, 2.6-naphthalene dicarboxylic acid, 1.4-chlorohexanedicarboxylic acid, trimethic anhydride, saturated polyhydric alcohol: ethylene glycol. 1.4 butanediol, 1.5bentanediol. 1,6 hexanediol, propylene glycol. polytetramethylene glycol, diethylene glycol, polyethylene glycol, triethylene glycol,
Neopedothyl glycol. 1.4 The method for producing a resin film-coated metal plate according to claim 1, which is obtained by the synthesis of cyclohexane dimetatool, trimethylolpropane, and pentaerythritol. (6) The thickness of the polyester resin film is 3 to 50 mm.
The method for producing a resin film-coated metal plate according to claim 1, wherein the diameter is .mu.m.