JPH01249331A - Manufacture of metallic sheet coated with polyester resin superior in processability - Google Patents

Abstract

PURPOSE:To enable the title sheet to be widely applied as a material for a can be imparting excellent adhesion processing, corrosion resistance processing, post-heat resistance, by a method wherein a polyester film having a specific resin composition layer is laminated continuously at a high speed to one side or both sides of a metallic sheet. CONSTITUTION:0.1-5.0g/m<2> of a polymeric composition containing at least a kind out of an epoxy group, hydroxyl group, amide group, ester group carboxyl group, urethane group, acrylic group and amino group within a molecule is applied to one side of a polyester film whose softening starting temperature is 170-235 deg.C, crystalline melting temperature is 210-250 deg.C, breaking extension is 150-400%, 75-99% of ester repeating unit is an ethylene terephthalate unit. Then the polyester film is laminated to one side or both sides of a metallic sheet heat to a sphere of (crystalline melting temperature-50) deg.C - (crystalline melting temperature+50) deg.C so that its coating surface of its polymeric composition comes into contact with the surface of the metallic sheet.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a method for producing a polyester resin-coated metal plate with excellent processability C1. A specific polyester film coated with a polymer composition having one or more of ester groups, carboxyl groups, urethane groups, acrylic groups, and amino groups in the molecule is heated to a temperature of ±50°C the crystal melting temperature of the polyester film. This invention relates to a polyester resin-coated metal plate laminated on one or both sides of a metal plate.

[Conventional technology]

Traditionally, in the can manufacturing industry, metal plates such as tinplate, electrolytic chromic acid treated steel sheets, and aluminum were coated once or multiple times. The baking process was not only complicated, but also required a long baking time.Also, since a large amount of solvent was emitted during coating film formation, the emitted solvent had to be led to a special incinerator and incinerated in order to prevent pollution. In order to solve these drawbacks, attempts have been made to laminate a thermoplastic resin film to a metal plate.

Examples include a polyolefin film laminated on a metal plate (JP-A-53-141786) and a polyethylene terephthalate film laminated on a metal plate without using an adhesive (JP-A-60-47103, JP-A-6O-168643). ), or those in which a biaxially stretched polyethylene terephthalate film is laminated onto a metal plate using an adhesive (JP-A-61-20736, JP-A-61-149341) have been disclosed.

[Problem to be solved by the invention]

However, when a metal plate laminated with a polyolefin film is used as a container material, the polyolefin film has no barrier properties against the contents, so corrosive media easily permeate through the polyolefin film and corrode the metal plate. It had drawbacks. In addition, polyolefin film usually has a melting point within the range of 100 to 170°C, so when it undergoes a post-heating process (usually 170 to 210°C) such as external printing during the can manufacturing process, the polyolefin film becomes molten and cannot be manufactured. It tends to soften and adhere to can tools, significantly reducing workability.

JP 60-47103, JP 60-168641=
In the case where a polyethylene terephthalate film is laminated to a metal plate without using the disclosed adhesive, the amorphous, non-oriented polyethylene terephthalate resin j- generated near the interface of the metal plate has good adhesive strength with the metal plate. However, when post-heat treatment is applied during the can manufacturing process, it becomes amorphous and
The non-oriented polyethylene terephthalate resin layer forms random spherulites, which significantly reduces the adhesion to the metal plate (2. If stored for a long period of time, filamentous corrosion is likely to occur, significantly degrading the appearance). are doing.

JP-A-61-20736 and JP-A-61-149341 disclose biaxially oriented polyethylene terephthalate film laminated onto a metal plate using a specific adhesive. The polyethylene terephthalate film laminated on a metal plate has excellent barrier properties and exhibits good anticorrosion effects against various contents because the polyethylene terephthalate film is stretched into two wheels. In addition, since an adhesive exhibiting good adhesive strength is present between the biaxially stretched polyethylene terephthalate film and the metal plate, the biaxially stretched polyethylene terephthalate film is firmly adhered to the metal plate.

In addition, because the film is laminated to a metal plate at a temperature below the melting point of the biaxially stretched polyethylene terephthalate film, non-oriented, amorphous polyethylene terephthalate resin is produced, as seen in Japanese Patent Publication No. 60-47103 and Japanese Patent Application Publication No. 60-16864. Therefore, processing adhesion and processing corrosion resistance do not deteriorate even after various post-heating steps are performed in the can manufacturing process.

However, since biaxially oriented polyethylene terephthalate film has tightly oriented crystals, the free movement of molecules is restricted by the oriented crystal regions, so it is required for deep drawing and easy open end processing, which require severe processing. When rivets or scoring are applied to the film, cracks tend to form in the biaxially stretched polyethylene terephthalate film, which limits processability.

[Means to solve the problem]

The present invention aims to solve the above-mentioned problems (as a result of various studies, the present invention is one in which a polyester film having a specific resin composition layer is laminated continuously at high speed on one or both sides of a metal plate. The polyester resin-coated metal sheet obtained by this method has many excellent properties such as processing adhesion, processing corrosion resistance, and post-heating resistance, so it can be used for cans that have undergone severe processing such as scoring and riveting. It can be widely applied as a material for cans that requires external printing of lids, squeezed cans, two- or three-time squeezed cans, high-back mortars, crowns, and caps that have been drawn and lightly ironed.

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

First, as a polyester film, at least 75 to 999 of the ester repeating units consist of ethylene terephthalate units, and the remaining 1 to 2596 ester repeating units consist of phthalic acid, isophthalic acid, terephthalic acid, succinic acid, azelaic acid, etc. , adipic acid, sebacic acid, dodecanedioic acid, diphenylcarboxylic acid, Z, 6-naphthalene dicarboxylic acid, 1.4-cyclohexanedicarboxylic acid, and trimethic anhydride; and ethylene glycol, 1.4 Butanediol, 1.
5bentanediol% 1.6 hexanediol, propylene glycol, polytetramethylene glycol, trimethylene glycol, triethylene glycol, neopentyl glycol, 1.4 cyclohequinane dimethanol, trimethylolpropane, pentaerythritol
The species or two or more saturated polyhydric alcohols are used.

Such a polyester resin can be formed into a film using a known extruder and provided as an unstretched polyester film, but after the film is formed and stretched in both the longitudinal and lateral directions,
It is more preferable to use a polyester film that has been subjected to a heat setting process because it improves the barrier properties of the polyester film.

Although the thickness of the polyester film is not particularly limited, it is preferably 5 to 50 μm.

If the thickness is less than 5 μm, the lamination workability will be significantly reduced and sufficient processing corrosion resistance will not be obtained. On the other hand, if the thickness is more than 50 μm, it will be less economical than epoxy paints widely used in the can manufacturing field. Not on point.

Such a polyester film has a softening start temperature of 170
The temperature is preferably within the range of ~235°C. The softening start temperature here refers to the temperature at which a needle starts penetrating the polyester film when the temperature is raised at a temperature increase rate of 10"C/rnin using a thermomechanical analyzer (TMAloo, manufactured by Seiko Electronics Co., Ltd.). temperature.

When the softening start temperature is 235° C. or higher, the processability of the polyester film decreases and cracks are likely to occur when deep drawing is performed. On the other hand, if the softening start temperature is 170° C. or lower, when normal external printing is applied and baked in the can manufacturing process, the temperature will be higher than the softening temperature of the polyester film, and workability will be significantly reduced, which is not practical.

Next (=, the crystal melting temperature of the polyester film is also important, and is preferably within the range of 210 to 250°C.

The crystal melting temperature here refers to the differential scanning calorimeter (881
0, manufactured by Seiko Electronics Co., Ltd.) (from the second, 10°C/m
An endothermic peak is observed when the temperature is raised at a temperature increase rate of in. This is the temperature that indicates the maximum depth of the endothermic peak.

The crystal melting temperature of polyester film is 250' (j2
If the polyester film itself becomes very rigid, processability becomes poor.

On the other hand, when the crystal melting temperature is C=210° C. or lower, the heat resistance of the polyester film itself decreases, and when post-heating is applied in the can-making process, the mechanical strength decreases significantly.

Next, the mechanical properties of the polyester film are also one of the important factors, and it is particularly desirable that the elongation at break of the polyester film is within the range of 150 to 40,096.

Here, the elongation at break of the polyester film is measured using a normal tensile tester at a tensile rate of 1 at a constant temperature of 25°C.
It is determined by performing a tensile test at 00 mm/rnin.

When the elongation at break of the polyester film is below 15096 Jl, the processability of the polyester film becomes poor,
When subjected to severe processing such as deep drawing or stretching, the film is prone to cracking due to its lack of ductility. On the other hand, when the elongation at break exceeds 4005% J2, thickness unevenness tends to occur during film molding, and in particular, it tends to break during the biaxial stretching process, which is not practical.

Next, the polymer composition applied to one side of the polyester film contains one or more of epoxy groups, hydroxyl groups, amide groups, ester groups, carboxyl groups, urethane groups, acrylic groups, and amino groups in the molecule. Preferably.

Examples of these polymer compositions include epoxy resins, phenol resins, nylon resins, polyester resins, modified vinyl resins, phletane resins, acrylic resins, and urethane resins.

The form of such a polymer composition is not particularly limited, but in order to apply a thin film onto a polyester film, it is preferably in a solution state that can be roll coated or spray coated. In addition, after applying the polymer composition in a solution state,
After drying in an open dryer, the polymer composition is preferably tack-free.

If the tack of the polymer composition is large, it is possible to wind the film, but when unwinding, the polymer composition tends to set off onto the uncoated surface of the polyester film, which is not preferable.

The drying temperature of the polymer composition in the dryer oven is also important, and the drying temperature is preferably in the range of 60 to 150°C. If the drying temperature is lower than 60° C., the solvent releasability will be significantly reduced and the tack of the polymer composition will become large, making it impractical.

On the other hand, if the drying temperature is 150° C. or higher, the chemical reaction of the polymer composition will proceed significantly during the drying process, and the adhesion to the metal plate described below will be significantly reduced, and the shape of the film will easily collapse.

When applying the polymer composition to a polyester film, the diluting solvent may be water or an organic solvent, but a low boiling point solvent is preferred in view of drying properties when the dryer is open.

Although the process of applying the polymer composition to the polyester film is satisfactory as described above, the present purpose is to add pigments and dyes to the polymer composition in order to improve the aesthetic appearance, to the extent that it is acceptable. May be blended.

Next, the coating weight of the polymer composition is particularly important, and the dry weight is preferably 0.1 to 5.0 g/m2, more preferably 0.1 to 1.0 g/m2. If the coating weight is less than 0.1 g 7 m 2 , the continuous thin film coating of the polymer composition becomes difficult and uniform coating becomes difficult. On the other hand, when the coating weight exceeds 5.0 si/mzB, the adhesion strength decreases significantly when the metal plate and polyester film are heated and integrated and then subjected to deep drawing.

Furthermore, the solvent releasability of the polymer composition on the polyester film in a dryer oven is also significantly reduced, resulting in a significant decrease in workability.

It is relatively easy to continuously apply a polymer composition onto a polyester film to a dry weight within the range of 0.1 to 5.0 g/m2, but it is difficult to apply it continuously and uniformly onto a strip metal plate. is extremely difficult.

The reason for this is that strip-shaped metal plates lack flatness ζ compared to polyester film, resulting in a marked drop in thin film coating properties, and the disadvantage that coaters for strip-shaped metal plates require higher equipment costs compared to coaters for plastic films. This is because it has

Next, examples of the metal plate used in the present invention include sheet-shaped and coil-shaped steel plates, steel foils, and aluminum plates, or those metal plates subjected to surface treatment.

Special features: Electrolytic chromic acid treated steel sheets or ultra-thin tin-plated steel sheets, nickel-plated steel sheets, galvanized steel sheets, and chromium hydrated steel sheets with a two-layer structure of metallic chromium on the bottom layer and hydrated chromium oxide on the top layer. Surface treated with an oxide or two-layer structure consisting of an upper layer of hydrated chromium oxide and a lower layer of metallic chromium, or phosphate-treated, chromate-treated, or chromium-chromate-treated aluminum. The board has excellent adhesion C1 to the polymer composition.

Next, in the process of laminating the polyester film coated with the polymer composition on one side in advance to the metal plate, the (crystalline melting temperature -50) of the polyester film is
A metal plate heated in the range of 'C to (crystal melting temperature +50)C is laminated on one or both sides of the metal plate so that the coated side of the polymer composition is in contact with the surface of the metal plate, and after lamination, it is rapidly cooled and slowly cooled. There is no problem even if you go through this process.

One of the features of the present invention is that the polyester film can be firmly bonded to the metal plate only through the above process, and the polymer composition is applied to the metal plate in advance and the metal plate is heated to a predetermined lamination temperature. Even when heated, the polyester film shows no adhesion to the metal plate.

Here, if the lamination temperature is higher than the crystalline melting temperature of the polyester film + 50'C or more, the polyester film will not partially deteriorate due to heat, and when used as a material for cans, it will have a barrier property against the contents. The metal plate becomes more susceptible to corrosion.

When the polyester film used in the present invention is laminated on a metal plate heated to C2 above the melting point of the polyester film, a non-oriented and amorphous polyester layer is produced. Compared to polyester film, it is difficult to recrystallize even when subjected to post-heat treatment, so there is little decrease in barrier properties, and there is also little decrease in adhesiveness to the metal plate due to the adhesive interposed between the polyester film and the metal plate. −
On the other hand, if the lamination temperature is below the (crystal melting temperature -50) of the polyester film, the adhesion between the polyester film and the metal plate tends to decrease, and when deep drawing is performed, the polyester film peels off more easily than the metal plate. Become.

Methods for heating the metal plate include the known hot air circulation heat transfer method, resistance heating method, induction heating method, and heat roll heat transfer method, and are not particularly limited, but equipment costs and equipment simplification should be taken into consideration. In this case, the heat roll heat transfer method is preferable.

Next, the surface temperature of the laminating roll when laminating the polyester film onto the metal plate is also an important factor in the present invention.

That is, the surface temperature of the laminating roll is 80 to 180
It is necessary to control the temperature within the range of ℃. If the surface temperature falls below 80°C, it becomes easy for bubbles to form during lamination, and once air bubbles form, there is no improvement even after post-heat treatment.

This is thought to be due to the fact that the polymer compositions have different reactivity towards the metal plate surface or the polyester film surface during the lamination process.

That is, the polymer composition easily reacts with the surface of the metal plate heated to a high temperature. On the other hand, the reactivity between the polyester film and the polymer composition is controlled by the temperature at the interface between the polyester film and the polymer composition, and the lower the temperature of the laminating roll, the lower the temperature at the interface between the film and the polymer composition. and the reactivity becomes smaller.

Therefore, at a roll surface temperature of 80°C or less, the polymer composition reacts well only with the metal plate heated to a high temperature, so the polymer composition is transferred from the polyester film side to the metal plate, and as a result, the polymer composition Air bubbles can easily form between objects and the polyester film.

On the other hand, when the surface temperature of the laminate roll is 180° C. or higher, it approaches the crystal melting temperature of the polyester film, so the laminate roll C copolyester film tends to soften and adhere, significantly reducing workability.

The material of the laminating roll can be chrome plated roll, ceramic roll, or rubber roll.
In order to achieve beautiful lamination at high speed, a rubber roll is preferable for I:.

The rubber material of the rubber roll is not particularly limited, but silicone rolls with excellent thermal conductivity and heat resistance are preferred.

〔Example〕

This will be explained in detail in Examples below.

Example 1 A cold rolled steel plate with a thickness of 0.21 mm was electrolytically degreased in a 70 g/l sodium hydroxide solution, pickled with a 100 v'l sulfuric acid solution, washed with water, and then treated with chromic anhydride 609/l. l
, in a solution of 3 v'l of sodium fluoride at a current density of 2
Cathode electrolytic treatment was performed under the conditions of 0 A7 dm2 and an electrolyte temperature of 50° C., and immediately washed with hot water of 80° C. and dried. A polyester film treated under the conditions shown below was continuously laminated on one side of the electrolytically chromic acid treated steel plate having a medium size of 56 mm and 300 mm.

Biaxially oriented polyester film 25 μm Softening start temperature 176°C Crystal melting temperature 215°C Breaking elongation 330% Dry weight of polymer composition 0.2 g/m2 Drying temperature of polymer composition Heating method for 100'C steel plate Heat roll lamination Temperature of steel plate immediately before: 185℃ Roll Silicone roll Laminating roll surface temperature Mail 154
Cooling method after lamination at °C Slow cooling 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 120 g/J of chromic anhydride and 0.8 v' of hydrofluoric acid. ! , using an electrolyte of 0.5 v'l of sulfuric acid and a current density of 50 Vdrn2. After performing chromic acid treatment at an electrolyte temperature of 60° C., it was washed with water.

Subsequently, using an electrolyte containing 1011 stannous sulfate, 20 g/J of phenol sulfonic acid (6096 aqueous solution), and 5 V'l of ethoxylated α-caftol sulfonic acid, a current density of 5 A7 dm2 and an electrolyte temperature of 40°C were used. After tin plating, wash with water and then chromic anhydride 50 V/I
! , using an electrolyte of 0.1 Jl of sulfuric acid and a current density of 30
After post-treatment was carried out under the conditions of A/dm2 and electrolyte temperature of 55°C, it was washed with hot water of 80°C and dried. Obtained width 300
1! ll11 strip bridge thin Romu tin plated steel plate one side 1
; Polyester films treated under the following conditions were laminated continuously under the following conditions.

Biaxially oriented polyester film 25 μm Softening start temperature 192°C Crystal melting temperature 239°C Elongation at break
210% Dry weight of polymer composition 0.6 g/m2 Drying temperature of polymer composition 120'C Steel plate heating method Steel plate temperature just before heat roll lamination 219°C Roll Silicon roll Surface of laminating roll Temperature max 175
Cooling method after lamination at °C Slow cooling 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 40 vyt of nickel chloride (hexahydrate) and sulfuric acid =
y KeA/ (hexahydrate salt) 250 v/1! , a current density of 10 A using a Wacht bath consisting of 40 g/l of boric acid.
/dm2, 0.6g/m2 nickel plating at a bath temperature of 45°C, and after washing with water, 30v'l of sodium dichromate.
Chromate treatment was carried out in a solution at a current density of 10 ψm2 and an electrolyte temperature of 45°C, washed with water, and dried. On one side of the obtained strip-shaped nickel-plated steel plate with a width of 300si,
The polyester films treated under the conditions shown below were laminated continuously under the conditions shown below.

Biaxially oriented polyester film 16 μm Softening start temperature 212°C Crystal melting temperature 241°C Elongation at break 17296 Dry weight of polymer composition 1.56/m2 Drying temperature of polymer composition 120°C Steel plate heating method
Steel plate temperature just before heat roll lamination 25
5°C lamination) Roll Silicone roll Surface temperature of laminating roll max 128°C Cooling method after lamination Slow cooling example 4 A cold-rolled steel sheet similar to Example 1 was subjected to the same pretreatment as Example 1. , tin sulfate 80 Jl, phenolsulfonic acid (6096 aqueous solution) 609/J, ethoxylated α-naphtholsulfonic acid 5 g/l electrolyte under the conditions of current density 15 A, 'dm2 and electrolyte temperature 40°C. After tin plating, reflow treatment was performed and water was washed, followed by chromium plating using an electrolyte containing 30 v'l of chromic anhydride and 0.39/l of sulfuric acid at a current density of 40)y'dm2 and an electrolyte temperature of 50°C. It was treated with acid, washed with water, and dried.

A polyester film treated under the following conditions was continuously laminated on one side of the obtained belt-shaped silver-plated steel plate having a width of 300 mm under the following conditions.

Biaxially oriented polyester film 25μm softening start temperature J, 76℃ crystal melting temperature
215°C Breaking elongation 330% Dry weight of polymer composition 2.09/m2 Drying temperature of polymer kneaded product 80°C Heating method of steel plate Steel plate temperature immediately before heat roll lamination 215°C Laminating roll Silicone roll Laminating roll Surface temperature max 16
Cooling method after lamination at 5°C Slow cooling example 5 An aluminum plate with a thickness of 0.3III11 was heated to 30'a
After degreasing by cathode electrolysis in 1 liter of sodium carbonate solution, washing with water, immersion treatment in a bath containing 60 tall of phosphoric acid, 10 vol of chromic acid, and 5 Jl of sodium fluoride at a bath temperature of 25°C, washing with water, and drying. .

A polyester film treated under the following conditions was continuously laminated on one side of the obtained belt-shaped aluminum plate having a width of 300 aai under the following conditions.

Polyester film 30μm Softening start temperature 235℃ Crystal melting temperature 250'C elongation at break
155% Polymer Composition Dry It 1.5 g/
Drying temperature of m2 polymer composition 135℃ Aluminum plate heating method Heat roll Temperature of aluminum plate immediately before lamination 245℃ Lamination roll Silicone roll Lamination roll surface temperature max l 50℃ Cooling method after lamination Rapid cooling comparative example 1 Implementation Using the same steel plates as in Example 1, lamination was carried out continuously under the same conditions as in Example 1 except for the polyester film.

Biaxially oriented polyethylene terephthalate film (product name Lumirror Azuma) 25 μm Softening start temperature 240'C Crystal melting temperature
257° C. Breaking Elongation 12596 Ratio Example 2 Using the same steel plates as in Example 2, they were laminated continuously under the same conditions as in Example 2 except for the polyester film.

Biaxially oriented polyethylene terephthalate 25 μm film (trade name: Emblet, Uniteca H) Softening start temperature 238°C Crystal melting temperature 257°C Elongation at break 138% Comparative example 3 Using the same aluminum plate as in Example 5, a polyester film was prepared. Except for this, lamination was carried out continuously under the same conditions as in Example 5 except for the following conditions.

Unstretched polyethylene terephthalate 30 μm film (product name: Tetron Sheet Kijin ■) Softening start temperature
242°C Crystal melting temperature 254°C Breaking elongation
11096 Comparative Example 4 Using the same steel plate as in Example 1, lamination was carried out continuously under the same conditions as in Example 1 except for the temperature immediately before laminating the polyester film and the steel plate.

Biaxially oriented polyester film 25μm polyester resin: ethylene glycol and terephthalic acid 859
6/Isophthalic acid condensation polymer softening onset temperature 192°C Crystal melting temperature
239°C elongation at break
21096 Steel plate temperature just before lamination: 175℃
Comparative Example 5 Using the same aluminum plate as in Example 5, the 25 μm thick biaxially stretched polyethylene terephthalate film used in Comparative Example 1 was laminated continuously on one side without using an adhesive under the following conditions.

Heating method for aluminum plate Temperature of aluminum plate just before heat roll lamination 280'C laminating roll Silicone roll Surface temperature of laminating roll max l Q Cooling method after 5℃ lamination Metal plate laminated with polyester film only on one side after rapid cooling A polyester resin-coated metal plate was coated with an epoxy resin paint on the other side of the sheet to a dry weight of 8 SQL/dm2, and then baked at 195°C for 10 minutes.The metal plate was evaluated using the following test method. The results are shown in Table 1.

(1) Metal plate plating amount M (1 constant The plating amount and film amount were measured using a fluorescent X-ray method.

(2) Stretching process of polyester resin-coated metal plate After cutting the polyester resin-coated metal plate into 10 cm (width) x 30 cm (length), apply palm oil to both sides, and then cut the polyester resin-coated metal plate at right angles to the rolling direction of the polyester resin-coated metal plate. The limit at which cracks appear in the polyester resin film was defined as the critical reduction rate.

The limit reduction rate (ε) is calculated when tO is the thickness of the polyester resin-coated metal plate before re-rolling, and t is the thickness of the polyester resin-coated metal plate at which cracks begin to appear in the polyester resin film.The limit reduction rate (ε') is
It was calculated as = + (to-t)÷to)X100.

(3) Drawing process of polyester resin-coated metal plate The polyester resin-coated metal plate was punched out into a disc with a diameter of 140 mm, and the drawing ratio was 2.
55, the cylindrical cup was drawn, and the degree of cracking of the polyester resin was evaluated as 5 points (no cracking or peeling), 4 points,
3 points, 2 points, 1 point (Evaluation was divided into 5 grades depending on the degree of cracking and peeling.

(4) Score processing of polyester resin-coated metal plate After cutting the polyester resin-coated metal plate into 30ao x 70mm, from the opposite side of the polyester resin-coated side, cut the blade width 25mm.
A straight score tool having a cutting edge angle of 60' and a length of 50 m was used to cut into a metal plate with a load of 600 kg, and the plate thickness at the point where cracks began to appear in the polyester resin was taken as the critical score residual thickness.

〔Effect of the invention〕

The thus obtained metal plate laminated with a polyester film on one or both sides has excellent processing corrosion resistance, so it can be used for easy-open lids, deep-drawn cans or lightly ironed cans, crowns, etc., which have been subjected to severe processing such as scoring and re-petting. It can be widely applied as a material for containers such as caps.

Claims (1)

[Claims] Softening start temperature is 170-235℃, crystal melting temperature is 21
On one side of a polyester film exhibiting an elongation at break of 150 to 400% at 0 to 250°C and in which at least 75 to 99% of the ester repeating units are ethylene terephthalate units,
A simple substance or a mixture of a polymer composition having one or more of epoxy group, hydroxyl group, amide group, ester group, carboxyl group, urethane group, acrylic group, and amino group in the molecule is 0.1 to 5% by dry weight. The polyester film coated with .0 g/m^2 is placed in contact with one or both sides of a metal plate heated within the range of (crystal melting temperature +50) °C to (crystal melting temperature -50) °C of the polyester film. A method for manufacturing a laminated polyester resin-coated metal plate with excellent workability.