JP2003311883A - Manufacturing method for resin-coated metal sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method for a resin-coated metal sheet excellent in economical efficiency and can-making properties, excellent in the flavor properties of an obtained metal can, and hard to generate a defective appearance (whitening of a resin film) on the outer surface of the metal can by hot water sterilization treatment performed after the filling with content. <P>SOLUTION: The resin coated metal sheet is manufactured by a method wherein a molten resin film obtained in such a state that olefinic resins are allowed to meet with each other at both ends using a T-die is cooled and solidified and both ends are subsequently cut off to obtain a resin film (A) and a resin film (B), and a method for laminating both resin films (A) and (B) to a heated metal sheet. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing a resin-coated metal plate. More specifically, the present invention relates to a method for producing a resin-coated metal plate having excellent can-making properties (for example, drawing / ironing processability) and flavor properties, and a resin suitable for a metal can to be sterilized with warm water. The present invention relates to a method for manufacturing a coated metal plate.

[0002]

2. Description of the Related Art Conventionally, for the purpose of preventing corrosion, the inner surface and the outer surface of a metal can are coated with various thermosetting resins such as epoxy type and phenol type which are dissolved or dispersed in a solvent.
The coating of metal surfaces has been widely practiced. However, this method of coating a thermosetting resin has drawbacks that it takes a long time to dry the coating material, resulting in reduced productivity and often causing undesirable problems such as environmental pollution due to a large amount of organic solvent.

In order to solve such a drawback, a method of coating a metal plate with a thermoplastic resin by a melt extrusion method has been disclosed (for example, refer to Patent Document 1). Further, there is disclosed a method in which a melt-extruded thermoplastic resin is once cooled and solidified, and then pressure-bonded to a heated metal plate (see, for example, Patent Document 2). Further, there is disclosed a method of press-bonding an unoriented film of polyethylene terephthalate and / or polybutylene terephthalate produced by a melt extrusion method onto a heated metal plate (for example, refer to Patent Document 3). However, in these thermoplastic resin coating methods, when the molten resin is extruded in layers from the T-die, the width of the molten resin film is greatly reduced (referred to as neck-in), which is several tens of centimeters with respect to the resin width required for coating. It was necessary to form a film with a wide width, which was not a satisfactory method from the economical point of view.

In order to solve such a drawback, a method of reducing the neck-in by using a polyester prepared by blending a polyester obtained by copolymerizing a trifunctional or higher functional polybasic acid or a polyhydric alcohol component has been disclosed. (For example, see Patent Documents 4 and 5). However, in these coating methods, the polyester obtained by copolymerizing a trifunctional or higher polybasic acid or polyhydric alcohol component is likely to be thermally deteriorated in the melting process from the extruder to the T-die, and even if a heat stabilizer is used in combination. Foreign substances (for example, gel-like foreign substances or foreign substances whose core is a deteriorated product) are likely to be generated in the obtained molten resin film, and cracks originating from the foreign substances are generated in the resin coating layer during can making. It was not satisfactory as a coated metal plate.

[0005]

[Patent Document 1] Japanese Patent Application Laid-Open No. 57-203545

[Patent Document 2] Japanese Patent Laid-Open No. 10-309775

[Patent Document 3] Japanese Patent Laid-Open No. 2001-1447

[Patent Document 4] Japanese Patent Laid-Open No. 10-86308

[Patent Document 5] Japanese Patent Laid-Open No. 2000-71388

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above problems of the prior art. That is, the neck-in at the time of melt extrusion is small, and since foreign matter is unlikely to occur in the obtained molten resin film, it is excellent in economical efficiency and can-making property, and the flavor property of the obtained metal can is excellent, and the contents are The present invention provides a method for producing a resin-coated metal plate in which appearance defects (whitening of a resin film) on the outer surface of a metal can are less likely to occur in a warm water sterilization treatment carried out after the filling.

[0007]

An object of the present invention is to cover one surface of a metal plate with a resin film (A) composed of a crystalline polyester having an melting point of 180 ° C. or higher and an olefin polymer and to melt the other surface with a melting point of 180 ° C. In the above-mentioned production method for coating the resin film (B) made of crystalline polyester, both ends are cut and removed after cooling and solidification of the molten resin film obtained in a state where the olefin polymer is joined at both ends using a T die. Method for obtaining resin film (A) and resin film (B) and resin film (A)
And a method for producing a resin-coated metal plate, which comprises laminating the resin film (B) on a heated metal plate, wherein the resin film (A) comprises polyethylene terephthalate and polybutyle terephthalate at 60:40 to 30: 70:30 by weight of polyester and olefinic polymer 70:30 to 10
The resin layer (B) is made of polyester of 60:40 to 30: 70% by weight of polyethylene terephthalate and polybutylene terephthalate. This is achieved by the manufacturing method.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, a dicarboxylic acid component other than terephthalic acid and a glycol component other than ethylene glycol and butanediol can be used as long as the characteristics of polyethylene terephthalate and polybutylene terephthalate are not impaired. For example, as dicarboxylic acids, aromatic dicarboxylic acids such as isophthalic acid, orthophthalic acid, naphthalene dicarboxylic acid, diphenyl sulfone dicarboxylic acid, 5-sodium sulfoisophthalic acid, oxalic acid, succinic acid, adipic acid, sebacic acid, decane dicarboxylic acid,
Aliphatic dicarboxylic acids such as maleic acid, fumaric acid and dimer acid, oxycarboxylic acids such as p-oxybenzoic acid, and alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid can be used. As glycol components other than ethylene glycol and butanediol, aliphatic glycols such as propanediol, pentanediol, hexanediol and neopentyl glycol, alicyclic glycols such as cyclohexanedimethanol, aromatic compounds such as bisphenol A and bisphenol S, etc. Glycol can be used.

In the polyester of the present invention, if necessary, an antioxidant, a heat stabilizer, an ultraviolet absorber, a plasticizer,
Pigments, antistatic agents, lubricants, crystal nucleating agents, lubricants composed of inorganic or organic particles, etc. may be added.

The method for producing the polyester in the present invention is not particularly limited. That is, any of those produced by the transesterification method or the direct polymerization method can be used. Further, it may be produced by a solid phase polymerization method to increase the molecular weight. Furthermore, from the viewpoint of reducing the amount of oligomers from the polyester resin in the pastelize treatment, retort treatment, etc., which is carried out after filling the can with contents, use polyester with a low oligomer content produced by the reduced pressure solid-state polymerization method. Is preferred.

It is preferable that the blend ratios of the polyethylene terephthalate and the polybutylene terephthalate of the polyester of the resin film (A) and the resin film (B) are the same.
The reason is that, from the viewpoint of saving the waste of the resin, when the resin including both ends obtained by cutting and removing the resin extruded in layers after cooling and solidifying is reused in the central portion of the resin film (A), This is because the quality of the coated resin film is stable.

The melting point of the polyester used in the present invention is 180 ° C. or more. Can-making property (in drawing and ironing, the resin on the inner surface of the can secures the releasability of the punch, and on the resin on the outer surface of the can, It is necessary to prevent galling [vertical scratches on the resin film].

The olefin polymer blended with the polyester is not particularly limited. Low density polyethylene, medium density polyethylene, high density polyethylene, linear low density polyethylene, ultra high molecular weight polyethylene, polypropylene, ethylene-propylene copolymer, ethylene-butene copolymer, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer Polymers, ethylene-vinyl alcohol copolymers, ionomers and the like can be used.

Layered resin film (A) extruded from a T-die
It is preferable that the olefin-based polymer used at both end portions and the central portion and the olefin-based polymer used at both end portions of the resin film (B) are the same. The reason is that, from the viewpoint of eliminating waste of resin, when the resin including both ends obtained by cutting and removing the resin extruded in layers after cooling and solidifying is reused in the central portion of the resin film (A), This is because the quality of the coated resin film is stable. In the present invention, when the resin including both ends is reused in the central portion of the resin film (A), the reuse ratio is not particularly limited, but is preferably 5 to 60% by weight.

In the present invention, when a polyester and an olefin polymer are extruded in layers from a T-die, both ends (one side is 5
It is necessary to use an olefin-based polymer for the part (cm or less).

In the present invention, a polymer obtained by dry blending or melt-mixing polyester and an olefin polymer is melted in a known single-screw or twin-screw extruder, and then a known multi-manifold die such as an edge lamination type is used. To obtain a layered molten resin film.

In the present invention, as a cooling and solidifying method, a known method in which a layer of molten resin is brought into contact with a rotating cooling roll from a T-die can be used. When the molten resin is brought into contact with the cooling roll, it is preferable to employ a method of forcibly blowing air or a method of adhering it by static electricity. or,
In both the forced air blowing method and the electrostatic adhesion method, it is more preferable to perform the method in which both end portions and the central portion of the layered resin are independent.

In the present invention, the resin film obtained by cooling and solidifying and then cutting off both ends is laminated directly on the heated metal plate, or after cooling and solidifying, both ends are cut off and obtained. Any of the methods in which the resin film is once wound and then laminated on a metal plate heated in another step can be used.

In the latter coating method, the cooled solidified product is longitudinally stretched (for example, 2.0 to 6.0 times stretched at a temperature not lower than the glass transition temperature of polyester and lower than the cold crystallization temperature), and further stretched. It is preferable to carry out heat treatment (for example, at a temperature of 50 ° C. or higher and a melting point of polyester of −20 ° C. for 1 to 20 seconds) under the conditions. The reason is that after the wound resin film roll is stored, when the resin film roll is coated on the heated metal plate, the wrinkles caused by the breakage of the resin film due to the unwinding tension and the temporal shrinkage during the storage of the resin film roll. This is because it is preferable for suppressing blocking and the like.

In the present invention, a surface-treated steel plate such as tin-free steel, an aluminum plate, an aluminum alloy plate, or a surface-treated aluminum plate or an aluminum alloy plate can be used as the metal plate. These metal plates have a polyester melting point of -20 ° C or higher and a melting point of +1
After heating to 50 ° C., the resin film (A) and the resin film (B) are simultaneously or sequentially laminated on a metal plate using a laminating roll, and subsequently, this laminated metal plate is melted at a melting point of polyester + 10 ° C. or higher and a melting point of 10 ° C. or more. After heating at + 60 ° C., water cooling and / or air cooling is performed to obtain a resin-coated metal plate.

In the present invention, the thickness of the resin film on the metal plate is not particularly limited, but 10 to 50 μm is preferable from the viewpoint of coating effect (rust prevention) and economical efficiency.

[0022]

EXAMPLES The present invention will be described below with reference to examples. [Evaluation methods]

(1) Melting Point of Polyester 10 mg of a sample obtained by heating and melting a polyester composition at 300 ° C. for 5 minutes and then rapidly cooling it with liquid nitrogen was used.
10 using a differential scanning calorimeter (DSC) in a nitrogen stream
When the exothermic / endothermic curve (DSC curve) was measured at a temperature rising rate of ° C / min, the peak temperature of the endothermic peak associated with melting was taken as the melting point Tm (° C).

(2) Neck-in amount T Die discharge port width (60 cm) and average value (Acm) of resin film width after cooling and solidification (resin film width before cutting and removing both ends) measured at n = 3 ) Was used to determine the neck-in amount (cm) by the following formula. The neck-in amount of 5 cm or less was evaluated as being practical. Neck-in amount (cm) = 60-A

(3) Method for producing resin-coated metal plate Aluminum alloy plate heated to 250 ° C. (thickness: 0.26
mm 3004 series alloy plate) is laminated with the resin film (A) on one side and the resin film (B) on the other side at the same time, and then 27
After heating at 5 ° C., it was rapidly cooled in water to prepare a laminated aluminum plate.

(4) Releasable laminated aluminum plate of the resin on the inner surface of the can and the processing punch was made into a can with n = 10, and the degree of buckling occurring at the upper part of the formed can was visually observed. The evaluation criteria were set as follows, and ◯ was evaluated as practical. ○: No buckling of the can opening △: Buckling occurred in about 1/3 of the circumference of the can opening ×: Buckling occurred in more than 1/3 of the circumference of the can opening

(5) Scuffing resistance of the outer surface of the can (longitudinal scratches on the resin on the outer surface of the can) A laminated aluminum plate was made into a can with n = 10, and the degree of occurrence of scratches on the resin on the outer surface of the body of the can body was visually observed. did.
The evaluation criteria were set as follows, and ◯ was evaluated as practical. ◯: No scratches were found Δ: Scratches were found on about 1/3 of the outer surface X: Severe scratches were found on more than 1/3 of the outer surface

(6) Flavoring A laminated aluminum plate of 5 cm square was dipped in d-limonene filled in a hermetically sealed glass container, and then allowed to stand in a thermostatic chamber at 40 ° C. for 10 days to adsorb d-limonene. Let
The d-limonene adhering to the surface is wiped off with Kimwipe and the weight W1 is measured. The laminated aluminum plate after measuring the weight W1 is vacuum dried at 60 ° C. for 24 hours, and then the weight W2 is measured. Furthermore, the weight W3 of the release film obtained by dissolving the aluminum plate of the laminated aluminum plate in an acid and drying it is measured. The adsorbed amount of d-limonene is calculated by the following formula and expressed in% by weight. Those having an adsorbed amount of D-limonene of 3% by weight or less are evaluated as being practical. Adsorption amount of d-limonene (% by weight) = (W1-W2) / W3
× 100

(7) Whitening of the outer surface of the can after hot water treatment The can obtained by making an aluminum laminate plate at 270 ° C.
Samples are those that have been heated for 40 seconds and then rapidly cooled in water. This sample was immersed in warm water of 80 ° C. for 10 minutes and then rapidly cooled in water to visually observe the outer surface of the can. The evaluation criteria were set as follows, and ○ was evaluated as practical. ◯: Whitening is inconspicuous △: Whitening is apparent, but the color of the aluminum alloy plate is visible ×: Color of the aluminum alloy plate is not visible due to whitening

[Abbreviations and Contents of Polyester and Olefin Polymer Used in Examples and Comparative Examples] (1) PET: polyethylene terephthalate (2) PBT: polybutylene terephthalate (3) CO-PES: terephthalic acid and ethylene glycol / Cyclohexanedimethanol (mol% 70/3
Copolymerized polyester with 0) (4) Olefin: Toughmer A-4085 (manufactured by Mitsui Chemicals, Inc., trade name) (5) Ionomer: Himilan 1706 (manufactured by Mitsui DuPont Polychemicals, trade name)

Example 1 As a raw material for the central portion of the resin film (A), 87% by weight of PET / PBT = 40/60% by weight of polyester and 13% by weight of olefin were melted at 280 ° C. to form a resin film (A). Olefin simple substance is melted at 250 ° C. as a raw material for both ends of the edge lamination type T die (olefin discharge port width / center discharge port width / olefin discharge port width = 2 cm / 56 cm / 2 cm,
Using a heating roll (heated to 260 ° C), cooling rolls (peripheral speed 2
0 m / min) (distance from the T-die to the ground point of the molten resin on the cooling roll is 15 cm, air is forcibly blown by separate devices for the center and both ends), then both ends (5 cm on each side) ) Was cut and removed and wound up to obtain a roll-shaped resin film having a thickness of 25 μm used for the resin film (A).

Further, P is used as a raw material for the central portion of the resin film (B).
ET / PBT = 40/60 wt% polyester 28
Melt at 0 ° C., melt olefin simple substance as a raw material for both ends of the resin film (B) at 250 ° C., and use edge lamination type T-die (olefin outlet width / central outlet width / olefin outlet) Width = 2 cm / 56 cm /
2 cm, heated to 260 ° C.) and cast into layers on a cooling roll (peripheral speed 20 m / min) (distance from T die to ground point of molten resin on cooling roll 15 cm, center part and both ends are separate) After forcibly blowing air with an apparatus, both ends (5 cm on one side) were cut and removed, and wound up to obtain a roll-shaped resin film having a thickness of 16 μm used for the resin film (B).

A resin film (A) is pressure-bonded to one surface of a 3004 series aluminum alloy plate (thickness 0.26 mm) heated to 250 ° C., and a resin film (B) is pressure-bonded to the other surface at 275 ° C.
After being heated to 1, it was rapidly cooled in water to obtain a laminated aluminum plate.

After applying a forming lubricant to the laminated aluminum plate thus obtained, it was heated and drawn at a plate temperature of 70 ° C. so that the resin film (A) was on the inner surface side of the can. Then, the temperature of the obtained cup was set to 40 ° C. and ironing was performed at a mold temperature of 80 ° C. to obtain a 350 ml size seamless can.

Melting point of polyester, neck-in amount during casting, can-making property (releasing property of resin film and punch on inner surface of can and degree of scratching of resin film on outer surface of can), flavor property, whitening of outer surface of can after hot water treatment The degree is shown in Table 1. The method of this embodiment is
A method for producing a resin-coated metal sheet having a small neck-in amount and excellent economic efficiency, a method for producing a resin-coated metal sheet having excellent can-making properties and flavor properties, and a metal having excellent hot water whitening resistance on the outer surface. It can be said that this is a method for producing a resin-coated metal plate from which a can is obtained.

Example 2 87% by weight of PET / PBT = 50/50% by weight polyester and 13% by weight of olefin were used as raw materials for the central portion of the resin film (A), and the raw material for the central portion of the resin film (B) was used. As PET / PBT = 50/5
A roll-shaped resin film having a thickness of 25 μm used for the resin film (A) and a roll-shaped resin film having a thickness of 16 μm used for the resin film (B) were obtained in the same manner as in Example 1 except that the content was 0% by weight.

Then, a laminated aluminum plate was prepared in the same manner as in Example 1, and a can was made to obtain a seamless can having a size of 350 ml.

[0038] Melting point of polyester, neck-in amount during casting, can-making property (releasing property of resin film and punch on inner surface of can and extent of scratching of resin film on outer surface of can), flavor property, whitening of outer surface of can after hot water treatment The degree is shown in Table 1. The method of this embodiment is
A method for producing a resin-coated metal sheet having a small neck-in amount and excellent economic efficiency, a method for producing a resin-coated metal sheet having excellent can-making properties and flavor properties, and a metal having excellent hot water whitening resistance on the outer surface. It can be said that this is a method for producing a resin-coated metal plate from which a can is obtained.

Example 3 87% by weight of PET / PBT = 40/60% by weight of polyester and 13% by weight of ionomer were used as raw materials for the central part of the resin film (A), and both ends of the resin film (A) Resin film (A) was prepared in the same manner as in Example 1 except that the ionomer was used as the raw material for both ends of the film (B).
A roll-shaped resin film having a thickness of 25 μm and a roll-shaped resin film having a thickness of 16 μm used for the resin film (B) were obtained.

Then, a laminated aluminum plate was prepared in the same manner as in Example 1 and made into a can of 350 ml in size.

Melting point of polyester, neck-in amount during casting, can-making property (releasability of resin film and punch on inner surface of can and degree of scratching of resin film on outer surface of can), flavor property, whitening of outer surface of can after hot water treatment The degree is shown in Table 1. The method of this embodiment is
A method for producing a resin-coated metal sheet having a small neck-in amount and excellent economic efficiency, a method for producing a resin-coated metal sheet having excellent can-making properties and flavor properties, and a metal having excellent hot water whitening resistance on the outer surface. It can be said that this is a method for producing a resin-coated metal plate from which a can is obtained.

Example 4 As a raw material for the central part of the resin film (A), 87% by weight of PET / PBT = 40/60% by weight polyester and 70% by weight of 13% by weight of olefin were used. The thickness used for the resin film (A) was 25 μm in the same manner as in Example 1 except that the polymer obtained by granulating the both ends cut and removed before obtaining A) was 30% by weight.
The thickness used for the roll-shaped resin film and the resin film (B) is 16μ
A roll-shaped resin film of m was obtained. Then, a laminated aluminum plate was prepared in the same manner as in Example 1, and a can was made into 350 ml.
Got a seamless can of size.

Melting point of polyester, neck-in amount during casting, can-making property (releasing property of resin film on inner surface of can and punch and degree of scratching of resin film on outer surface of can), flavor property, whitening of outer surface of can after hot water treatment The degree is shown in Table 1. The method of this embodiment is
A method for producing a resin-coated metal sheet having a small neck-in amount and excellent economic efficiency, a method for producing a resin-coated metal sheet having excellent can-making properties and flavor properties, and a metal having excellent hot water whitening resistance on the outer surface. It can be said that this is a method for producing a resin-coated metal plate from which a can is obtained.

Example 5: 87% by weight of PET / PBT = 40/60% by weight polyester and 70% by weight of olefin 13% by weight were used as raw materials for the central part of the resin film (A). 15% by weight of the polymer obtained by granulating the both ends cut and removed before obtaining A) and the polymer obtained by granulating the both ends cut and removed before obtaining the resin film (B) in Example 1. Was obtained in the same manner as in Example 1 except that the content was 15% by weight, to obtain a roll-shaped resin film having a thickness of 25 μm used for the resin film (A) and a roll-shaped resin film having a thickness of 16 μm used for the resin film (B). Then, a laminated aluminum plate was produced in the same manner as in Example 1, and a can was made to obtain a 350 ml size seamless can.

Melting point of polyester, neck-in amount during casting, can-making property (releasing property of resin film and punch on inner surface of can and degree of scratching of resin film on outer surface of can), flavor property, whitening of outer surface of can after hot water treatment The degree is shown in Table 1. The method of this embodiment is
A method for producing a resin-coated metal sheet having a small neck-in amount and excellent economic efficiency, a method for producing a resin-coated metal sheet having excellent can-making properties and flavor properties, and a metal having excellent hot water whitening resistance on the outer surface. It can be said that this is a method for producing a resin-coated metal plate from which a can is obtained.

Example 6 As a raw material for the central part of the resin film (A), 87% by weight of PET / PBT = 40/60% by weight polyester and 70% by weight of 13% by weight of olefin were used. The thickness used for the resin film (A) was 25 μm in the same manner as in Example 1 except that the polymer obtained by granulating the both ends cut and removed before obtaining B) was 30% by weight.
The thickness used for the roll-shaped resin film and the resin film (B) is 16μ
A roll-shaped resin film of m was obtained. Then, a laminated aluminum plate was prepared in the same manner as in Example 1, and a can was made into 350 ml.
Got a seamless can of size.

Melting point of polyester, neck-in amount during casting, can-making property (release property of can film on inner surface of can and punch and degree of scratching of resin film on outer surface of can), flavor property, whitening of outer surface of can after hot water treatment The degree is shown in Table 1. The method of this embodiment is
A method for producing a resin-coated metal sheet having a small neck-in amount and excellent economic efficiency, a method for producing a resin-coated metal sheet having excellent can-making properties and flavor properties, and a metal having excellent hot water whitening resistance on the outer surface. It can be said that this is a method for producing a resin-coated metal plate from which a can is obtained.

[Comparative Example 1] A rolled resin film was prepared in the same manner as in Example 1 except that the raw materials at both ends of the resin film (A) and the resin film (B) were PET / PBT = 40/60% by weight. Although it was tried to obtain the resin film, the method was not economical because the central portion having a large neck-in amount and a uniform thickness distribution could not be obtained unless both ends were cut and removed by 18 cm.

[Comparative Example 2] 87% by weight of PET / PBT = 20/80% by weight polyester and 13% by weight of olefin were used as raw materials for the central portion of the resin film (A), and raw materials for the central portion of the resin film (B) were used. As PET / PBT = 20/8
A film was formed in the same manner as in Example 1 except that 0 was used, but the resin film was often cracked between the cooling roll and the winding roll, and a resin film in a roll shape could not be stably obtained. It is not preferable as a film manufacturing method.

Comparative Example 3 87% by weight of PET / PBT = 70/30% by weight polyester and 13% by weight of olefin were used as the starting materials for the central part of the resin film (A), and the starting materials for the central part of the resin film (B) were used. As PET / PBT = 70/3
A roll-shaped resin film having a thickness of 25 μm used for the resin film (A) and a roll-shaped resin film having a thickness of 16 μm used for the resin film (B) were obtained in the same manner as in Example 1 except that the value was 0.

Then, a laminated aluminum plate was prepared in the same manner as in Example 1, and a can was made to obtain a 350 ml seamless can.

Melting point of polyester, neck-in amount during casting, can-making property (releasing property of resin film on inner surface of can and punch and scratching of resin on outer surface of can), flavor property, whitening of outer surface of can after hot water treatment Is shown in Table 1. This method is a method for producing a resin-coated metal sheet with a small amount of neck-in and excellent in economic efficiency, and was a method for producing a resin-coated metal sheet with excellent can-making properties and flavor properties, but the outer surface was resistant to warm water whitening. Since it is inferior in properties, it is not preferable as a method for producing a resin-coated metal plate.

[Comparative Example 4] 87% by weight of CO-PES and 13% by weight of olefin were used as raw materials for the central portion of the resin film (A), and CO-PE was used as raw material for the central portion of the resin film (B).
A resin film (A) was prepared in the same manner as in Example 1 except that S alone was used.
A roll-shaped resin film having a thickness of 25 μm and a roll-shaped resin film having a thickness of 16 μm used for the resin film (B) were obtained.

Then, a laminated aluminum plate was prepared in the same manner as in Example 1, and a can was made to obtain a seamless can having a size of 350 ml.

Melting point of polyester, neck-in amount during casting, can-making property (releasing property of resin film on inner surface of can and punch and scratching of resin on outer surface of can), flavor property, degree of whitening of outer surface of can after hot water treatment Is shown in Table 1. This method was a method for producing a resin-coated metal plate with a small neck-in amount and excellent economical efficiency. A metal plate (laminated aluminum plate) coated with this resin film was made into a can. The punch sticks and buckles occur all around the can opening,
Furthermore, since the outer surface of the resin on the outer surface of the can has scratches, the can-making property is inferior and the resin-coated metal plate (laminated aluminum plate) is also inferior in the flavor property, which is not preferable as a method for producing a resin-coated metal plate.

Comparative Example 5 Rolls were prepared in the same manner as in Example 1 except that 50% by weight of PET / PBT = 40/60% by weight polyester and 50% by weight of olefin were used as raw materials for the central portion of the resin film (A). A resin film was obtained.

Table 1 shows the melting point of polyester and the neck-in amount during casting. This method was a method for producing a resin film with a small neck-in amount and excellent economical efficiency, but the obtained resin-coated metal plate (laminated aluminum plate) had a poor flavor property, and the processing punch did not come off easily. Buckling occurred in about 1/3 of the opening, which is not preferable as a method for producing a resin-coated metal plate.

[0058]

[Table 1]

[0059]

Industrial Applicability The method for producing a resin-coated metal sheet of the present invention is not only an economical production method because it is possible to eliminate waste of raw materials, but also a production method by which a resin-coated metal sheet excellent in flavor can be obtained. Is. Furthermore, it is a method of producing a resin-coated metal plate having excellent can-making properties (particularly, the releasing property of the resin film on the can inner surface and the processing punch and the scratch resistance of the resin film on the can outer surface). Furthermore, since the appearance of the outer surface of the metal can (whitening of the resin film) is unlikely to occur in the warm water sterilization treatment performed after filling the contents, it can be said that this is a very useful method for producing a resin-coated metal plate.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) B29K 67:00 B29K 67:00 F term (reference) 3E061 AA15 AB21 AD01 3E062 AA04 AB02 AC03 JA01 JA07 JA08 JB22 JC02 JD08 4F100 AB01A AK03B AK03C AK41B AK41C AK42B BA02 BA03 BA07 BA27 EH23 EJ17 EK06 GB16 JA04B JA04C JA11B JA11C JL01 JL11 YY00B YY00C 4F207 AA03 AA24 AA25 AD03 AD08 AG03 AH55 KA01W17K17W23

Claims (3)

[Claims] 1. A resin film (B) consisting of a crystalline polyester having a melting point of 180 ° C. or higher and a crystalline polyester (A) having a melting point of 180 ° C. or higher as one body and a crystalline polyester having a melting point of 180 ° C. or higher on the other side. In a manufacturing method for coating a resin film (A) and a resin film (B), the molten resin film obtained by merging the olefin-based polymer at both ends with a T-die is cooled and solidified, and then both ends are cut and removed. And a resin film (A) and a resin film (B) are laminated on a heated metal plate, wherein the resin film (A) comprises polyethylene terephthalate and poly (ethylene terephthalate). Butyre terephthalate 60:40 to 30:70 wt% polyester and olefin polymer 70: 3
0 to 100: 0% by weight, and the resin film (B) is composed of polyethylene terephthalate and polybutylene terephthalate consisting of 60:40 to 30: 70% by weight polyester resin-coated metal Method of manufacturing a plate. 2. The resin according to claim 1, wherein the olefin polymer at both ends and the center of the resin film (A) and the olefin polymer at both ends of the resin film (B) are the same. A method for manufacturing a coated metal plate. 3. The resin-coated metal sheet according to claim 1, wherein the resin film (A) and the resin film (B) have the same blending ratio of polyethylene terephthalate and polybutylene terephthalate of polyester. Method.