JPS5882717A - Manufacture of polyester resin film-coated metal plate - Google Patents

Abstract

PURPOSE:To provide a coated metal plate which consists of an upper layer comprising a crystalline saturated polyester resin and of a lower layer comprising an amorphous polyester resin, by a method wherein a metal plate is heated to a melting point Tm, of a crystalline saturated polyester resin film, -Tm+ 160 deg.C, and after said film is laminated, the lamination is cooled within 60sec. CONSTITUTION:In case a crystalline saturated polyester resin film is laminated to a metal plate, the metal plate is heated to the melting point Tm, of said resin, -Tm+160 deg.C, and after said film is laminated, the lamination is cooled within 60sec. This forms a tow-layer structure comprising a crystalline saturated polyester resin for an upper layer and an unfixed polyester resin having a crystalline index of 0-20% for a lower layer, and permits the production, in a very high productivity, of a polyester resin film-coated metal plate which has said unfixed polyester resin layer with a thickness of not more than 40% of that of a total polyester resin layer and is not more than 20mum thick.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a metal plate coated with a crystalline saturated polyester resin film. It had a two-layer structure including a crystalline saturated polyester resin layer and an amorphous polyester resin layer on the lower N (the surface in contact with the base metal plate).

The present invention relates to a method for manufacturing a metal plate coated with a crystalline saturated polyester resin film with extremely high productivity.

Conventionally, the method of continuously coating a metal surface with a resin film is to apply an adhesive to the metal surface, heat it in an oven with a long distance capacity (to about 200°C), and laminate the resin film. It has generally been the case that the material is cooled or further cooled after being subjected to a post-heat treatment. However, such a method takes a long time to install an oven.

There are limitations due to equipment problems, and as a result, productivity is extremely low (speed: 20 to 30 m/m1n), production costs are high, and performance is not sufficient.

The reason for this is that it takes time for the adhesive to harden, and that the post-heating of the metal plate after laminating the film takes a long time, which increases the thermal history of the adhesive and film (and makes them more susceptible to thermal decomposition). (There were problems such as decreased performance.

- There is also a method of using a film coated with an adhesive on a crystalline saturated polyester film, but this method complicates the manufacturing process to create an adhesive film and is not economical. There was a problem.

Next, looking at the history of demand for resin film-coated metal sheets from the perspective of use, the main applications were interior and exterior building materials, electrical parts, storage case materials, vehicle interior materials, furniture and household goods materials, etc.; , it has become possible to use it as a material for containers, especially cans. In other words, the main material for cans has traditionally been tin, but due to the depletion of tin and the soaring price of tin, as well as changes in the content of cans, there has been a growing trend for cans made of tin to be coated on the inside. On the other hand, due to the rapid increase in demand for beverage cans, electrolytic chromate treated steel sheets (Tin Free 5tee+
--...The use of TF8 (hereinafter referred to as TF8) has been increasing and has achieved considerable results, and from the comparison with the tinplate mentioned above, T
FS has become highly regarded as a material for cans.

However, TFS still has some characteristics (mainly corrosion resistance) that are not as good as tinplate, and attempts have been made to cover it by painting, but there are limits to the improvement in 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 it is rarely put into practical use due to reasons such as low productivity and low productivity.

From this point of view, the present invention focuses on the usefulness as a material for cans, and also focuses on a crystalline saturated polyester resin film that has corrosion resistance, aesthetic properties, and mechanical properties for general use. The object is to provide a metal plate coated with a resin film, and has the following features and effects.

That is, in a method for producing a film-coated metal plate in which the metal surface is coated with a crystalline saturated polyester resin film under heat treatment of the base metal plate, when the film is laminated onto the strip-shaped base metal plate, the metal plate is Heat the crystalline saturated polyester resin film to a temperature equal to or higher than its melting point, and adhere the resin film to one or both sides of the film continuously and at high speed, maintaining the state of the crystalline saturated polyester resin on the upper layer of the film. It is characterized by a two-layer structure in which the adhesive surface that contacts the lower layer, that is, the metal plate, becomes an amorphous state while the adhesive is in contact with the metal plate.

The method of the present invention eliminates the need for lengthy and expensive furnace equipment after the film is laminated. In addition, it is possible to easily coat the metal plate with carbonate instead of coating the crystalline saturated polyester resin film with an adhesive.

The resin film-coated metal plate obtained by the method of the present invention is not only extremely effective as a material for cans, but also suitable for general use, being inexpensive and aesthetically pleasing.

High corrosion resistance 2 Can be widely used as a material with excellent mechanical properties.

The contents of the present invention will be explained in detail below.

First, the crystalline saturated polyester used in the method of the present invention needs to have a crystallinity of 25% or more, and if it is less than 25%, the corrosion resistance will be poor and it is not preferable.

The M crystalline saturated polyester can be obtained by the following synthesis of a saturated polyhydric carboxylic acid and a saturated polyhydric alcohol.

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 cyclohexane dicarboxylic acid, trimethic anhydride.

Saturated polyhydric alcohol: ethylene glycol, 1.4 butanediol, 1.5 bentanediol, 1.6 hexanediol, propylene glycol, polytetramethylene glycol9. Diethylene glycol.

Polyethylene glycol, triethylene glycol, neopentyl glycol, 1.4 cyclohexane dimetatool, trimethylolpropane, pentaeryth
Little.

Note that the crystallinity referred to herein is a value measured by a commonly used X-ray diffraction method.

Furthermore, additives such as stabilizers, pigments, antistatic agents, and rust preventives may be mixed into the film as required.

Next, the base metal plate used in the method of the present invention is a belt-shaped mild steel plate (including foil), an aluminum plate (including foil), or the surface of the metal plate is subjected to one of the following surface treatments, namely (a) ; Plating of Sn, Zn, he, Pb, Ni, Cr or Cu (b); Multilayer plating of two or more metals shown in (a) above; (C) one of the metals shown in (a) above Plating of alloys containing the above (d); Examples include surface-treated steel sheets that have been subjected to composite plating containing one or more of the metals shown in 1d (a) above as main components.

It is also possible to use the above-mentioned base metal plate subjected to chromate treatment or phosphate treatment.

The heating temperature of the metal plate is preferably from the melting point (Tm) of the crystalline saturated polyester resin 1 film to Tm + 160°C.

The melting point (Tm) referred to herein is determined from the endothermic peak by differential thermal analysis. If the resin is a mixture of two or more types and has two or more endothermic peaks,
The endothermic peak due to the main component of the resin is defined as Tm.

If the heating temperature of the metal plate is below the melting point (Tm), the adhesion of the resin film will be poor, and if it is above Tm+160°C, the resin film will undergo significant thermal deterioration and it will be difficult to maintain the crystal structure.

Further, the heating time is 60 seconds or less, preferably 10 seconds or less. If the heating time exceeds 60 seconds, the entire crystalline saturated polyester resin film becomes amorphous, which significantly reduces the corrosion resistance of the film-coated steel sheet, which is not preferable.

Japanese Patent Publication No. 49-34180 uses a crystalline saturated polyester resin film as an adhesive.

In this method, almost all crystalline saturated polyester is changed into amorphous polyester, and metal plates are bonded together using an adhesive.

If the upper layer is a crystalline polyester resin as in the invention of the present application, it has excellent corrosion resistance and mechanical properties, and if the lower layer is an amorphous polyester resin, the adhesion to the metal plate is excellent. Further, if the steel sheet has a two-layer structure as described above, a film-coated steel sheet with excellent corrosion resistance, adhesion, and mechanical properties can be obtained.

As mentioned above, in order to obtain a film-coated steel sheet with a two-layer structure using a crystalline saturated polyester resin film, the above-mentioned heating conditions are This is particularly important, and it is desirable that the amorphous polyester layer be as thin as possible. Note that the amorphous polyester herein refers to polyester with a crystallinity of 20% or less.

The thickness of the film is not particularly limited, but is 5 to 100 μm.
is common, and in this case, the degree of crystallinity can be reduced to 2 by heating.
It is desirable to limit the amount of material that changes to 0% or less amorphous polyester to 40% or less of the total thickness and 20I1m or less. When the thickness is 40% or more or 20 μm or more, there is a tendency for the whitening phenomenon to be significant and the properties to deteriorate in corrosion resistance tests such as exposure to steam at 100° C. or higher. Further, the amorphous polyester resin layer does not need to be 100% amorphous, but the crystallinity of the layer needs to be 20% or less.

If it exceeds 20%, the adhesion will decrease, which is not preferable.

In addition, as for the heating method, in order to obtain a coated metal plate rapidly and continuously, it is necessary to rapidly heat the metal plate to a temperature corresponding to the bonding conditions of the film.

This rapid heating includes oven heating, infrared heating, high frequency heating, resistance heating, etc. Any method may be used, but it is necessary to heat the metal plate to a predetermined plate temperature. As a result of studies on energy-efficient and effective rapid heating methods, it has been found that a manufacturing method using resistance heating is preferable.

Furthermore, the time required to raise the temperature from normal temperature to the appropriate temperature by resistance heating is not particularly limited, but it is preferably 1 to 20 seconds. Further, after coating with a film, it is preferable to rapidly cool the film depending on the characteristics of the film. Regarding the cooling method, water cooling, cooling with liquid nitrogen, or other methods may be used, but it is preferable that the temperature is lowered to below the melting point of the base film within 1 second in a water bath at 0 to 90°C.

As mentioned above, coated metal plates laminated at high speed by resistance heating using coating metal plates and films have good corrosion resistance and adhesion when applied to general paints or crystalline saturated polyester resin films using heating methods using adhesives. It is much better than the one produced by.

Below, examples will be shown and the effects thereof will be explained.

Example 1 Electrolytic chromic acid treatment was performed to form metallic chromium (100F/G) as a lower layer and chromium hydrated oxide (151F/G, as chromium) on the upper layer on one side (film-coated surface) of a mild steel plate. , plated plate with only metallic chromium (100 coats/d) formed on one side (width: 1 m, plate thickness: 0.2111
f) a crystalline saturated polyester film (manufactured by ICI,
(trade name: Melinex S, 20 μm) was laminated under the following conditions to obtain a coated metal plate.

Creation conditions (1) Heating method: Resistance heating (a) Voltage (between conductor and roll): 150V (b) Temperature of metal plate during temporary bonding: 240°C (c) Temperature of metal plate just before cooling: 280°C ) Heating time from room temperature to appropriate temperature by resistance heating = 6 seconds (e) Time to cool after lamination = 2 seconds (2)
Lamination speed: 200 m/rrlil The coated metal plate prepared under the above conditions was stretched by 20% and then subjected to a 180° peeling test (attraction speed: 100 w/m1n). As a result,
The film was broken and could not be peeled off, and the adhesion was good. In addition, as a corrosion resistance test of the film-coated surface, a citric acid aqueous solution adjusted to pH 2.2 (
After filling 50cc) and leaving it in an atmosphere at 55℃ for one month, the amount of iron ions eluted into the contents was 0.1 ppm.
It was below. In addition, an amorphous polyester layer having a thickness of about 2 μm was formed on the portion in contact with the base metal plate surface, and its crystallinity was 5%.

In addition, by heating in an oven, it can be heated for an additional 260°C after lamination.
When heated for 1 minute at ℃, almost all of it changes to amorphous polyester, and in the iron elution test similar to the bait record,
ppm of iron ions were eluted.

Example 2 Sn-plated (2,8F/#) metal plate (plate width = 1m.

Immediately after heating a crystalline saturated polyester film (plate thickness: 0.15ff) by infrared heating (manufactured by Toshi).

After laminating a coated metal plate (trade name: Nilmirror F, 50 μm), the coated metal plate was rapidly cooled.

Creation conditions (1) Heating method: Infrared heating (a) Temperature of metal plate just before cooling: 300°C (b) Time until cooling after lamination: 10 seconds (2) Lamination speed: 100 m/min Created under the above conditions After stretching the coated metal plate by 2096 degrees, it is 180 degrees! As a result of the 'II release test, the film was broken and could not be peeled off, and the adhesion was good. In addition, as a corrosion resistance test for the film-coated surface, a can obtained in the same manner as in Example 1 was filled with a phosphoric acid aqueous solution (50 cc) adjusted to pH 2.2, and then left in an atmosphere at 55°C for one month. The amount of iron ions eluted into the material was 0.42 ppm. Furthermore, as a corrosion resistance test on the non-film-covered surface, a salt spray test was conducted according to JIS Z2371, and as a result, no red rust was observed even after 12 hours. In addition, an amorphous polyester layer having a thickness of about 10 μm was formed on the portion in contact with the base metal plate surface, and its crystallinity was 10%.

Example 3 A metal plate (width: 1 m, thickness: 0.321 fi) with Ni plating (4,5 f/d) on both sides was subjected to electrolytic chromic acid treatment, and one side (film-coated side) was coated with metallic chromium ( 6,0q
A crystalline saturated polyester film (manufactured by ICI) was prepared using a metal plate on which chromium hydrated oxide (8q/wf, as chromium) was formed as a lower layer and as an upper layer.

(trade name: Melinex 377.20 μm) was laminated under the following conditions to obtain a coated metal plate.

Creation conditions (1) Heating method: Resistance heating (a) Voltage (between conductor and roll): 115V (0
) Temperature of metal plate during temporary bonding: 240℃ (c) Temperature of metal plate just before cooling: 320℃ (d) Time to raise temperature from room temperature to appropriate temperature by resistance heating: 12 seconds (e) Until cooling after lamination Time: 1 second (2)
Lamination speed: 100 m/min After stretching the coated metal plate created under the above conditions by 20%, a 180° peel test (
As a result, the film was broken and could not be peeled off, and the adhesion was good. In addition, as a corrosion resistance test of the film-coated surface, Example 1
After filling a can obtained in the same manner as above with an acetic acid aqueous solution (50 cc) adjusted to pH 2.2 and leaving it in an atmosphere at 55°C for one month, the amount of iron ions eluted into the contents was 0.1 p.
It was below pm.

Furthermore, as a corrosion resistance test on the non-film coated surface, J1.
As a result of testing with S Z 2371, 15 hours
Even after that, no red rust was observed.

Example 4 Zn, Ni alloy plating on both sides of a mild steel plate (Zn: 14 min β
, Ni: 1.2 fA/) L/metal plate (plate width = 1 m.

Plate thickness: 0.32m+1) is electrolytically treated with chromic acid, and one side (film-covered side) is coated with metallic chromium (30cm/ltf).
is formed on the lower layer, chromium hydrated oxide (10 capes/d, as chromium) is formed on the upper layer, and one side is formed with metallic chromium (6
0q/ll) as the lower layer and chromium hydrated oxide (5 capes ~.

Using a metal plate with (as chromium) formed on the upper layer,
Crystalline saturated polyester film (manufactured by Banjin).

Product name: W3030.60 (μm) was laminated under the following conditions to obtain a coated metal plate.

Creation conditions (1) Heating method: Resistance heating (a) Voltage (between conductor and roll): 100V (b) Temperature of metal plate during temporary bonding = 120°C (c) Temperature of metal plate just before cooling: 250°C ( d) Time to raise temperature from room temperature to appropriate temperature by resistance heating = 12 seconds (e) Time to cool down after lamination: 20 seconds (2)
Lamination speed: 100 m/min The coated metal plate prepared under the above conditions was stretched by 20% and then subjected to a 1800 peel test (
As a result, the film was broken and could not be peeled off, and the adhesion was good.

Further, as a corrosion resistance test on the outer surface of the can during can molding, the non-film coated surface was tested according to JIS Z2371, and as a result, no red rust was observed even after 20 hours.

Note that an amorphous polyester layer having a thickness of about 20 μm was formed on the portion in contact with the base metal plate surface, and its crystallinity was 20%.

Example 5 A coated metal plate was obtained by laminating crystalline saturated polyester (manufactured by IC1, trade name: Melinex 0.20 μm) under the following conditions using a rolled steel foil of 50 μm that had been subjected to chromate treatment (Cr: 3qβ). Ta.

Creation conditions (1) Heating method: Induction heating (a) Temperature of metal plate just before cooling: 280°C (0)
Time until cooling after lamination: 10 seconds (2) Lamination speed: 2.0-m/min As a result of conducting the same peel test and corrosion resistance test as in Example 1, the same dimpled results as in Example 1 were obtained. Example 6 Crystalline saturated polyester (manufactured by Toyobo, trade name: E-5000, 50 μm) was laminated and coated using a 100 μm aluminum foil that had been chromate treated (Cr: 1 β) under the following conditions. I got a metal plate.

Creation conditions (1) Heating method: Gas oven heating (a) Temperature of metal plate just before cooling: 280°C (b) Time until cooling after lamination: 5 seconds (2) Lamination speed: 50
As a result of conducting the same adhesion test and corrosion resistance test as in Example 1, the adhesion was poor as in Example 1, and the amount of aluminum ions eluted was 0.5 ppm.

Example 7 Chromate treatment (Cr: 3 W/111) A mild steel plate with a thickness of 0 and 251 ff was laminated with crystalline saturated polyester film (trade name: Nilmirror 810.20 μm, manufactured by Toshi Co., Ltd.) in the same manner as in Example 1. A coated metal plate was obtained.

An amorphous polyester layer having a thickness of approximately 1 μm was formed on the portion that contacted the surface of the base metal plate, and its crystallinity was 3%. Further, when the same peeling test and iron elution test as in Example 1 were conducted, almost the same results as in Example 1 were obtained.

90-

Claims (1)

[Claims] When laminating a crystalline saturated polyester resin film on a metal plate, the plate temperature of the metal plate is set to the melting point (Tm) of the resin
The film is heated to Tm + 160°C, and after laminating the film, it is cooled within 60 seconds to form a two-layer structure of a crystalline saturated polyester resin for the upper layer and an amorphous polyester resin with a crystallinity of ~20% for the underwear. A method for producing a metal plate coated with a polyester resin film, characterized in that the thickness of the amorphous polyester resin layer is 40% or less of the total polyester resin layer and 20 μm or less.