JP2003291199A - Production method for resin-coated metal plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a production method for a resin-coated metal plate excellent in economical efficiency and can-making property, wherein impact resistance hardly lowers in heating for baking coating of an external surface to be beautifully made after can making, and which is suitable for a metal can to be executed with a hot water sterilization treatment. <P>SOLUTION: The production method for a resin-coated metal plate comprises a method for cutting and removing the opposite ends of the metal plate to obtain a plastic film (A) and a plastic film (B) after the molten resin film obtained in a state that an olefin polymer is merged at the opposite ends of the metal plate using a T-die is cooled and solidified, and a method for laminating the resin film (A) and the resin film (B) on the heated metal plate. <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 sheet which is excellent in can-making properties (for example, drawability / ironing processability) and impact resistance, and which is suitable for a metal can to be sterilized by warm water.

[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.

Further, the resin for coating the resin-coated metal plate used in the squeezing / ironing can requires not only excellent moldability capable of following the can making (squeezing / ironing), but also beautiful after the can making. It is required that the impact resistance is not deteriorated even in the heating of the outer surface baking coating, which is carried out for the purpose of improving the efficiency. However, the above-mentioned resin-coated metal plate often deteriorates in impact resistance, and thus does not satisfy the requirements for impact resistance.

[0006]

[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

[0007]

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 economic efficiency and can-making property, and external baking coating is performed for the purpose of beauty after can-making. The impact resistance does not easily decrease even when heated,
The present invention also provides a method for producing a resin-coated metal plate suitable for a metal can to be sterilized by warm water.

[0008]

An object of the present invention is to provide a resin film (A) mainly composed of crystalline polyester on one surface of a metal plate.
And a resin film (B) made of a crystalline polyester on the other surface, a molten resin film obtained by merging the olefin polymer at both ends with a T-die by cooling and solidifying. A resin-coated metal plate comprising a method of later cutting and removing both ends to obtain a resin film (A) and a resin film (B), and a method of laminating the resin film (A) and the resin film (B) on a heated metal plate. And the resin film (A) has a composite structure of (I) layer / (II) layer,
The layer comprises 60:40 to 30: 70% by weight of polyethylene terephthalate and polybutylene phthalate, (II)
The layer is made of crystalline polyester and polyester elastomer of 95: 5 to 70: 30% by weight of polyester and olefin polymer of 70:30 to 100: 0% by weight, and the resin film (B) is made of polyethylene terephthalate and polybutylene terephthalate. Is 60:40 to 30:70
It is achieved by a method for producing a resin-coated metal sheet, which is characterized by comprising polyester by weight.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION In the layer (I) of the resin film (A) and the resin film (B) of the present invention, a dicarboxylic acid component other than terephthalic acid and ethylene are used as long as the characteristics of polyethylene terephthalate and polybutylene terephthalate are not impaired. Glycol components other than glycol and butanediol can be used. 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.

The crystalline polyester forming the layer (II) of the resin film (A) in the present invention is a polymer composed of a dicarboxylic acid component and a glycol component, and as dicarboxylic acid, terephthalic acid, isophthalic acid, orthophthalic acid,
Aromatic dicarboxylic acids such as naphthalene dicarboxylic acid, diphenyl sulfone dicarboxylic acid, 5-sodium sulfoisophthalic acid, Aliphatic acids such as oxalic acid, succinic acid, adipic acid, sebacic acid, decane dicarboxylic acid, maleic acid, fumaric acid, dimer acid An oxycarboxylic acid such as dicarboxylic acid or p-oxybenzoic acid, or an alicyclic dicarboxylic acid such as cyclohexanedicarboxylic acid can be used. As glycol components, ethylene glycol, propanediol, butanediol, pentanediol, hexanediol,
Aliphatic glycols such as neopentyl glycol, alicyclic glycols such as cyclohexanedimethanol, and aromatic glycols such as bisphenol A and bisphenol S can be used.

The ratio of the crystalline polyester to the polyester elastomer in the layer (II) of the resin film (A) in the present invention must be 95: 5 to 70: 30% by weight. When the polyester elastomer content is less than 5% by weight, impact resistance is low, which is not preferable. On the other hand, if it exceeds 30% by weight, ejection from the T-die becomes unstable, which is not preferable.

The polyester elastomer is a polyester whose hard segment is mainly composed of terephthalic acid residues and ethylene glycol residues or butanediol residues, and aromatic dicarboxylic acids such as isophthalic acid and orthophthalic acid, adipic acid, sebacic acid, It may contain an aliphatic dicarboxylic acid such as decanedicarboxylic acid. The soft segment preferably contains 5 to 50 mol% of polytetramethylene oxide having a weight average molecular weight of 400 to 5,000.

The polyester in the present invention may contain an antioxidant, a heat stabilizer, an ultraviolet absorber, a plasticizer, if necessary.
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.

Layer (I) of resin film (A) and resin film (B)
It is preferable that the blending ratio of polyethylene terephthalate and polybutylene terephthalate of the polyester is the same. The reason is that, when the resin containing both ends obtained by cutting and removing the resin extruded in layers after cooling and solidifying is reused in the (II) layer of the resin film (A) from the viewpoint of saving waste of the resin, This is because the quality of the resin film coated on the plate is stable.

The method for producing the polyester elastomer 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.

The melting point of the polyester used in the present invention is 180 ° C. or more. Can-making properties (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 in the (II) layer of the resin film (A) 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 in both ends of the layer (II) and the olefin-based polymer used in both ends of the resin film (B) are the same. The reason is that, when the resin containing both ends obtained by cutting and removing the resin extruded in layers after cooling and solidifying is reused in the (II) layer of the resin film (A) from the viewpoint of saving waste of the resin, This is because the quality of the resin film coated on the plate is stable.

In the present invention, when the resin including both ends is reused in the (II) layer of the resin film (A), the reuse ratio is not particularly limited, but is preferably 5 to 90% by weight.

In the present invention, when the polyester and the olefin-based polymer are extruded in a layer form from a T die, both end portions (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 a 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, a method of directly laminating a resin film obtained by cutting and removing both ends after cooling and solidifying, or by cooling and solidifying and then cutting and removing both ends is 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 point of polyester and lower than the cold crystallization temperature) and further strained. 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. However, in the case of laminating the resin film (A) on a metal plate, it is preferable that the (II> layer side and the metal plate are brought into contact with each other in order to ensure canning property.

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), impact resistance and economical efficiency.

[0028]

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 melting and melting a polyester composition at 300 ° C. for 5 minutes and then rapidly cooling 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 resin 3004 series alloy plate), the resin film (A) is laminated on one surface and the resin film (B) is laminated on the other surface at the same time.
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 manufactured at n = 10, and the degree of buckling occurring at the upper part of the molded 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) A can obtained by making an impact-resistant aluminum laminate plate at 280 ° C.
A sample of 7 cm square is cut out from the center of the body wall of the can which is heated in 40 seconds and quenched in water. A weight (600 g) having a tip diameter of 10 mm was dropped from a height of 10 cm on the surface corresponding to the outer surface of the can of this sample to give an impact. Then, the sample was placed on a glass container filled with 7% diluted hydrochloric acid (the sample was placed in a state where the convex portion was immersed), and after 3 days, the corrosion state of the convex portion was visually observed. The evaluation criteria were set as follows, and ◯ was evaluated as practical. ○: Corrosion of convex part not generated ×: Corrosion of convex part occurred

(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) PET-I: polyethylene terephthalate / isophthalate ( Repeating unit of ethylisophthalate 10
Mol%) (4) Elastomer: copolymer of polybutylene terephthalate and polybutylene oxide (weight average molecular weight is 1
000 butylene oxide repeating unit 15 mol%) (5) CO-PET: terephthalic acid and ethylene glycol / cyclohexanedimethanol (mol% 70/3
0) Copolymerized polyester (6) olefin: Tuffmer A-4085 (trade name, manufactured by Mitsui Chemicals, Inc.)

[Example 1] PET / PBT = 40/60% by weight polyester as the (I) layer raw material of the resin film (A), (I) layer raw material / elastomer = 85/15 weight as the (II) layer raw material Is melted at 280 ° C. and olefin simple substance is used as a raw material for both ends of the resin film (A) at 250 ° C.
And melted with an edge lamination type T-die (olefin outlet width / central outlet width / olefin outlet width = 2 cm / 56 cm / 2 cm, heated to 260 ° C.) to form a layered cooling roll ( Peripheral speed 20m / min) After casting (distance from the T die to the grounding point of the molten resin on the cooling roll is 15cm, air is forcibly blown with a separate device at the center and both ends), then both ends ( One side (5 cm) is cut off and wound up, and the thickness used for the resin film (A) is 25
μm ((I) layer thickness 12.5 μm, (II) layer thickness 12.
A roll-shaped resin film having a thickness of 5 μm was obtained.

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) was pressure-bonded to one surface of a 3004 series aluminum alloy plate (thickness 0.26 mm) heated to 250 ° C. so that the (II) layer side was in contact with the aluminum alloy plate, and the other surface was coated with resin. The film (B) was pressure-bonded, heated to 275 ° C., and then rapidly cooled in water to obtain a laminated aluminum plate.

After applying a molding 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), degree of whitening of outer surface of can after hot water treatment, resistance to The impact properties are shown in Table 1. The method of the present example is a method for producing a resin-coated metal plate having a small neck-in amount and excellent in economic efficiency, excellent in can-making properties, and a metal can having excellent hot water whitening resistance and impact resistance on the outer surface. It can be said that this is a method for producing the obtained resin-coated metal plate.

Example 2 The thickness used for the resin film (A) is 25 μm in the same manner as in Example 1 except that the raw material for the (II) layer of the resin film A is PET-I / elastomer = 85/15% by weight. ((I) layer thickness 12.5 μm, (II) layer thickness 1
A roll-shaped resin film of 2.5 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 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 (release property of resin film and punch on inner surface of can and degree of scratching of resin film on outer surface of can), degree of whitening of outer surface of can after hot water treatment, resistance to The impact properties are shown in Table 1. The method of the present example is a method for producing a resin-coated metal plate having a small neck-in amount and excellent in economic efficiency, excellent in can-making properties, and a metal can having excellent hot water whitening resistance and impact resistance on the outer surface. It can be said that this is a method for producing the obtained resin-coated metal plate.

Example 3 As Example 1 except that the (II) layer raw material of the resin film A was (I) layer raw material / elastomer = 85/15% by weight of polyester of 87% by weight and olefin of 13% by weight. Similarly, the thickness used for the resin film (A) is 25 μm ((I) layer thickness 12.5 μm, (II) layer thickness 1
A roll-shaped resin film of 2.5 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 350 ml size seamless can.

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

Example 4 The (II) layer raw material of the resin film A was (I) layer raw material / elastomer = 85/15% by weight of polyester of 50% by weight, and before the resin film (A) was obtained in Example 1. The polymer obtained by granulating the both ends cut and removed into 50
A resin film (A) was prepared in the same manner as in Example 1 except that the weight% was changed.
The thickness used for is 25 μm ((I) layer thickness 12.5 μm,
(II) A roll-shaped resin film having a layer thickness of 12.5 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 (releasability of resin film and punch on inner surface of can and degree of scratching of resin film on outer surface of can), degree of whitening of outer surface of can after hot water treatment, resistance to The impact properties are shown in Table 1. The method of the present example is a method for producing a resin-coated metal plate having a small neck-in amount and excellent in economic efficiency, excellent in can-making properties, and a metal can having excellent hot water whitening resistance and impact resistance on the outer surface. It can be said that this is a method for producing the obtained resin-coated metal plate.

[Example 5] (II) layer raw material of resin film A: (I) layer raw material / elastomer = 85/15% by weight of polyester is 50% by weight and before obtaining the resin film (B) in Example 1. The polymer obtained by granulating the both ends cut and removed into 50
A resin film (A) was prepared in the same manner as in Example 1 except that the weight% was changed.
The thickness used for is 25 μm ((I) layer thickness 12.5 μm,
(II) A roll-shaped resin film having a layer thickness of 12.5 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 350 ml seamless can.

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), degree of whitening of outer surface of can after hot water treatment, resistance to The impact properties are shown in Table 1. The method of the present example is a method for producing a resin-coated metal plate having a small neck-in amount and excellent in economic efficiency, excellent in can-making properties, and a metal can having excellent hot water whitening resistance and impact resistance on the outer surface. It can be said that this is a method for producing the obtained resin-coated metal plate.

[Comparative Example 1] A rolled resin film was prepared in the same manner as in Example 1 except that the raw materials for 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 PET / PBT = 20/80 wt% polyester was used as the raw material for the (I) layer of the resin film (A), and PET was used as the raw material for the central portion of the resin film (B).
An attempt was made to form a film in the same manner as in Example 1 except that / PBT was set to 20/80, but the resin film was often cracked between the cooling roll and the winding roll, and a roll-shaped resin film was stably obtained. Therefore, it is not preferable as a method for producing a resin film.

COMPARATIVE EXAMPLE 3 PET / PBT = 70/30 wt% polyester was used as the raw material for the layer (I) of the resin film (A), and PET was used as the raw material for the central portion of the resin film (B).
Roll-shaped resin having a thickness of 25 μm ((I) layer thickness 12.5 μm, (II) layer thickness 12.5 μm) used for the resin film (A) in the same manner as in Example 1 except that / PBT = 70/30. A roll-shaped resin film having a thickness of 16 μm used for the film and the resin film (B) was 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 and punch on inner surface of can and degree of scratching of resin film on outer surface of can), degree of whitening of outer surface of can after hot water treatment, resistance to The impact properties are shown in Table 1. This method is a method for producing a resin-coated metal sheet having a small neck-in amount and excellent in economic efficiency, and was a method for producing a resin-coated metal sheet having excellent can-making properties and impact resistance. Since the whitening property is poor, it is not preferable as a method for producing a resin-coated metal plate.

[Comparative Example 4] (I) layer of resin film (A),
PET-I / elastomer = 85 as raw material for layer (II)
The thickness used for the resin film (A) was 25 μm ((I)
A roll-shaped resin film having a layer thickness of 12.5 μm and (II) a layer thickness of 12.5 μm) and a roll-shaped resin film having a thickness of 16 μm used for the resin film (B) were obtained.

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), degree of whitening of outer surface of can after hot water treatment, resistance to The impact properties are shown in Table 1. This method was a method of manufacturing a resin-coated metal sheet with a small amount of neck-in and excellent in economic efficiency, but since the inner surface resin of the can and the processing punch adhere to each other and buckling occurs, the resin-coated metal sheet It is not preferable as a manufacturing method.

[Comparative Example 5] The thickness used for the resin film (A) was the same as in Example 1 except that CO-PET was used as the raw material for the (II) layer of the resin film (A) and the resin film (B). 25μ
m ((I) layer thickness 12.5 μm, (II) layer thickness 12.5
A roll-shaped resin film having a thickness of 16 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 350 ml seamless can.

Melting point of polyester, neck-in amount during casting, can-making property (release property of resin film and punch on inner surface of can and extent of scratching of resin film on outer surface of can), degree of whitening on outer surface of can after hot water treatment, resistance to The impact properties are shown in Table 1. This method is a method for producing a resin-coated metal sheet having a small amount of neck-in and excellent in economic efficiency, and was a method for producing a resin-coated metal sheet having an excellent hot water whitening resistance on the outer surface, but the can-making property and the Since it has poor impact resistance, it is not preferable as a method for producing a resin-coated metal plate.

[Comparative Example 6] The same procedure as in Example 1 was carried out except that 50% by weight of polyester of PET / PBT = 40/60% by weight and 50% by weight of olefin were used as raw materials for the (II) layer of the resin film (A). The thickness used for the resin film (A) is 25
μm ((I) layer thickness 12.5 μm, (II) layer thickness 12.
A roll-shaped resin film having a thickness of 5 μm and a roll-shaped resin film having a thickness of 16 μm used for the resin film (B) were obtained. A roll-shaped resin film was obtained.

Melting point of polyester, neck-in amount during casting, can-making property (release property of resin film and punch on inner surface of can and degree of scratching of resin film on outer surface of can), degree of whitening of outer surface of can after hot water treatment, resistance to The impact properties are shown in Table 1. This method was a resin film manufacturing method with a small neck-in amount and excellent economical efficiency,
The obtained resin-coated metal plate is somewhat inferior in can-making property, which is not preferable as a method for producing a resin-coated metal plate.

[0065]

[Table 1]

[0066]

The method for producing a resin-coated metal sheet according to the present invention is not only an economically excellent production method because waste of raw materials can be eliminated, but also canning properties (especially, the resin film on the inner surface of the can and the processing punch can be used). This is a method for producing a resin-coated metal plate having excellent releasability and scratch resistance of the resin film on the outer surface of the can. In addition, the appearance of the outer surface of the metal can (poor whitening of the resin film) is less likely to occur in the warm water sterilization process that is performed after filling the contents. It can be said that this is a very useful method for producing a resin-coated metal sheet whose impact resistance is unlikely to deteriorate even if it is carried out.

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 4F100 AB01A AB10 AB31 AK03C                       AK41B AK41C AK41D AK41E                       AL05B AL05C AL05D AL05E                       AL09C BA05 BA07 BA10B                       BA10E GB16 GB23 JA04B                       JA04C JA04D JA11E YY00C                       YY00E                 4F207 AA03K AA24K AA45K AD03                       AG01 AG03 KA01 KA17 KB26                       KW23

Claims (4)

[Claims] 1. A resin film comprising a crystalline polyester (A) having a melting point of 180 ° C. or higher as a main component and a crystalline polyester (A) having a melting point of 180 ° C. or higher and a melting point of 180 ° C. or higher on the other side of the metal plate. In the manufacturing method for coating B), T
A method for obtaining a resin film (A) and a resin film (B) by cutting and removing both ends of a molten resin film obtained by merging the olefin polymer at both ends using a die, after cooling and solidifying, and a resin film ( A method for producing a resin-coated metal plate, which comprises laminating A) and a resin film (B) on a heated metal plate, wherein the resin film (A) is (I) layer / (II) layer / (I ) Layer is a composite structure, and the (I) layer comprises polyethylene terephthalate and polybutylene phthalate from 60:40 to 30:70.
(II) layer is crystalline polyester and polyester elastomer 95: 5 to 70: 30% by weight polyester and olefin polymer is 70: 3.
0 to 100: 0% by weight, and the resin film (B) is made of polyethylene terephthalate and polybutylene terephthalate from 60:40 to 30: 70% by weight of polyester. Method. 2. The hard segment of the polyester elastomer is a polyester having a terephthalic acid residue and an ethylene glycol residue and / or a butanediol residue as main components, and the soft segment is polybutylene oxide. Item 1. A method for producing a resin-coated metal plate according to item 1. 3. The olefin-based polymer of both ends of the resin film (A) and the (II) layer and the olefin-based polymer of both ends of the resin film (B) are the same. Method for producing a resin-coated metal plate. 4. The (I) layer of the resin film (A) and the resin film (B)
The method for producing a resin-coated metal plate according to claim 1, wherein the polyester terephthalate and the polybutylene terephthalate have the same blending ratio.