JP4099711B2 - Method for producing resin-coated metal sheet - Google Patents

Description

【００６２】
【発明の効果】
本発明の樹脂被覆金属板の製造方法は原料の無駄を省けるため、経済性に優れた製造方法であるばかりでなく、製缶性（特に、缶内面樹脂膜と加工ポンチの離型性と缶外面樹脂膜の耐キズつき性）に優れた樹脂被覆金属板が得られる製造方法である。さらに、内容物を充填後に実施される温水殺菌処理で金属缶外面の外観不良（樹脂膜の白化）が発生しにくく、製缶後に美麗化を目的として実施される外面焼付け塗装を想定した加熱を実施しても耐衝撃性が低下しにくい極めて有用な樹脂被覆金属板の製造方法といえる。[0001]
BACKGROUND OF THE INVENTION
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 that is excellent in can manufacturing property (for example, drawing / ironing workability) and impact resistance and suitable for a metal can that is subjected to hot water sterilization treatment.
[0002]
[Prior art]
Conventionally, the inner surface and outer surface of a metal can have been widely coated with a solution in which various thermosetting resins such as epoxy and phenol are dissolved or dispersed in a solvent for the purpose of preventing corrosion. Has been done. However, this thermosetting resin coating method has a drawback in that it takes a long time to dry the paint, so that productivity is lowered and undesired problems such as environmental pollution due to a large amount of organic solvent often occur.
[0003]
In order to solve such drawbacks, a method of coating a metal plate with a thermoplastic resin by a melt extrusion method is disclosed (for example, see Patent Document 1). Further, a method is disclosed 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, a method is disclosed in which an unoriented film of polyethylene terephthalate and / or polybutylene terephthalate produced by a melt extrusion method is pressure-bonded to a heated metal plate (see, for example, 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 (called neck-in), and several tens of centimeters relative 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 viewpoint of economy.
[0004]
In order to solve such a drawback, a method of reducing neck-in by using a polyester obtained by blending a polyester obtained by copolymerizing a tribasic or higher polybasic acid or a polyhydric alcohol component is disclosed (for example, (See Patent Documents 4 and 5.) However, in these coating methods, a polyester obtained by copolymerizing a tribasic or higher polybasic acid or a polyhydric alcohol component is likely to be thermally deteriorated in a melting process from an extruder to a T die, and a heat stabilizer may be used in combination. The resulting molten resin film is likely to generate foreign matters (for example, foreign matters having a gel-like foreign matter or deteriorated core), and the resin coating layer is cracked starting from the foreign matters during can making. It was not satisfactory as a coated metal plate.
[0005]
Resin-coated metal sheet coating resins used for squeezing and ironing cans are not only required to have excellent moldability to follow canning (drawing and ironing), but also to beautify after making the cans It is required that the impact resistance is not lowered even in the heating of the outer surface baking coating performed as described above. However, the resin-coated metal plate often has a reduced impact resistance, and does not satisfy the demand for impact resistance.
[0006]
[Patent Document 1]
JP-A-57-203545
[Patent Document 2]
JP-A-10-309775
[Patent Document 3]
JP 2001-1447 A
[Patent Document 4]
JP 10-86308 A
[Patent Document 5]
JP 2000-71388 A
[0007]
[Problems to be solved by the invention]
The object of the present invention is to solve the problems of the prior art. In other words, because the neck-in at the time of melt extrusion is small and foreign matter is not easily generated in the obtained molten resin film, it is excellent in economic efficiency and can-making properties, and is baked on the outside surface for the purpose of beautification after can-making Thus, the present invention provides a method for producing a resin-coated metal plate suitable for a metal can in which impact resistance is unlikely to decrease even during heating, and a hot water sterilization treatment is performed.
[0008]
[Means for Solving the Problems]
An object of the present invention is to coat a resin film (A) mainly composed of crystalline polyester having a melting point of 180 ° C. or higher on one side of a metal plate and to form a resin film (B) made of crystalline polyester having a melting point of 180 ° C. or higher on the other side. ), The molten resin film obtained in a state where the olefinic polymer is joined to both ends using a T die is cooled and solidified, and then both ends are cut and removed to obtain a resin film (A) and a resin film ( B) and a method for producing a resin-coated metal plate comprising a method of laminating a resin film (A) and a resin film (B) on a heated metal plate, and the resin film (A) is (I) Layer / (II) layer, wherein (I) layer comprises 60: 40-30: 70 wt% of polyethylene terephthalate and polybutylene phthalate, and (II) layer comprises 50 mol% or more of the total acid component Terephthalic acid residue and 5-50 mol % Is an aliphatic dicarboxylic acid residue having 10 or more carbon atoms and the olefin polymer is 70:30 to 100: 0% by weight, and the resin film (B) is 60:40 to polyethylene terephthalate and polybutylene terephthalate. This is achieved by a method for producing a resin-coated metal plate, which is made of 30: 70% by weight of polyester.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
In the resin film (A) (I) layer and resin film (B) of the present invention, a dicarboxylic acid component other than terephthalic acid and a glycol component other than ethylene glycol and butanediol are used so long as the properties of polyethylene terephthalate and polybutylene terephthalate are not impaired. Can be used. For example, as dicarboxylic acid, aromatic dicarboxylic acid such as isophthalic acid, orthophthalic acid, naphthalenedicarboxylic acid, diphenylsulfone dicarboxylic acid, 5-sodium sulfoisophthalic acid, oxalic acid, succinic acid, adipic acid, sebacic acid, decanedicarboxylic 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 neopentylglycol, alicyclic glycols such as cyclohexanedimethanol, and aromatics such as bisphenol A and bisphenol S Glycol can be used.
[0010]
In the polyester constituting the (II) layer of the resin film (A) in the present invention, 50 mol% or more of the total acid component is a terephthalic acid residue and 5 to 50 mol% is an aliphatic dicarboxylic acid having 10 or more carbon atoms. It is necessary. If the terephthalic acid residue is less than 50 mol%, the heat resistance is insufficient, and the releasability of the punch at the time of can-making is deteriorated. Examples of the aliphatic dicarboxylic acid having 10 or more carbon atoms include sebacic acid, eicoic acid, decanedicarboxylic acid, and dimer acid. Dimer acid is obtained by a dimerization reaction of a higher unsaturated fatty acid such as oleic acid, and usually has an unsaturated bond in the molecule, but it can also be used after hydrogenation to reduce the degree of unsaturation. Hydrogenation is more preferable because heat resistance and flexibility are improved. In addition, a linear branched structure, an alicyclic structure, and an aromatic ring structure are generated during the dimerization reaction, but these structures and amounts are not particularly limited. Aliphatic dicarboxylic acid residues having less than 10 carbon atoms are not preferred because they do not provide sufficient impact resistance. If the aliphatic dicarboxylic acid residue having 10 or more carbon atoms is less than 5 mol%, it is not preferable because the impact resistance is not sufficient. On the other hand, if it exceeds 50 mol%, not only the impact resistance is saturated but also the heat resistance is lowered, which is not preferable.
[0011]
The polyester constituting the (II) layer of the resin film (A) can be a dicarboxylic acid other than these acids, provided that the terephthalic acid residue and the aliphatic dicarboxylic acid residue having 10 or more carbon atoms satisfy the above range. Including an acid residue is not particularly limited. Moreover, one type of aliphatic dicarboxylic acid residue having 10 or more carbon atoms may be used, or two or more types may be used in combination. Further, the glycol residue of the polyester constituting the (II) layer of the resin film (A) is not particularly limited, and aliphatic such as ethylene glycol, propanediol, butanediol, pentanediol, hexanediol, neopentylglycol, etc. It may be a residue of an alicyclic glycol such as glycol or cyclohexanedimethanol, or an aromatic glycol such as bisphenol A or bisphenol S.
[0012]
In the polyester of the present invention, an antioxidant, a heat stabilizer, an ultraviolet absorber, a plasticizer, a pigment, an antistatic agent, a lubricant, a crystal nucleating agent, a lubricant composed of inorganic or organic particles, and the like are blended as necessary. May be.
[0013]
The method for producing the polyester in the present invention is not particularly limited. That is, it can be used even if it is produced by either the transesterification method or the direct polymerization method. Further, it may be produced by a solid phase polymerization method in order to increase the molecular weight. Furthermore, use a polyester with a low oligomer content produced by the low-pressure solid-state polymerization method from the viewpoint of reducing the amount of oligomers from the polyester resin in pastry treatment, retort treatment, etc. that are carried out after filling the contents in the can. Is preferred.
[0014]
It is preferable that the blend ratio of the polyethylene terephthalate and the polybutylene terephthalate of the polyester of the resin film (A) (I) and the resin film (B) is the same. The reason is that when the resin including both ends obtained by cutting and removing the resin extruded in a layer form after cooling and solidification is reused in the (II) layer of the resin film (A) from the viewpoint of eliminating the waste of the resin, This is because the quality of the resin film coated on the plate is stabilized.
[0015]
Polyester used in the present invention has a melting point of 180 ° C. or higher. Can manufacturing ability (in drawing and ironing process, the inner surface of the can ensures punch releasability, the outer surface of the can suppresses galling [ It is necessary from vertical scratches in the resin film]).
[0016]
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.
[0017]
It is preferable that the both ends of the layered resin film (A) extruded from the T-die and the olefin polymer used in the (II) layer and the olefin polymer used in both ends of the resin film (B) are the same. The reason is that when the resin including both ends obtained by cutting and removing the resin extruded in a layer form after cooling and solidification is reused in the (II) layer of the resin film (A) from the viewpoint of eliminating the waste of the resin, This is because the quality of the resin film coated on the plate is stabilized.
[0018]
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.
[0019]
In the present invention, when the polyester and the olefin polymer are extruded in a layer form from the T die, it is necessary to use the olefin polymer at both end portions (portions where one side is 5 cm or less).
[0020]
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 layered using a known multi-manifold die such as an edge lamination type. A molten resin film is obtained.
[0021]
In the present invention, as a cooling and solidification method, a known method in which a resin melted in a layer form from a T die is brought into contact with a rotated cooling roll 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 closely contacting with static electricity. Moreover, both the forced air spraying method and the electrostatic contact method are more preferable to carry out the method in which both end portions and the central portion of the layered resin are made independent.
[0022]
In the present invention, a method of directly laminating a resin film obtained by cutting and removing both ends after cooling and solidification on a heated metal plate, or a resin film obtained by cutting and removing both ends after cooling and solidification Any of the methods of once winding the film and laminating it on a metal plate heated in a separate process can be used.
[0023]
In the latter coating method, the cooled solidified material is longitudinally stretched (for example, stretched by 2.0 to 6.0 times at a temperature not lower than the glass transition temperature of the polyester and lower than the cold crystallization temperature), and further heat-treated under tension. It is preferable to carry out (for example, at a temperature of 50 ° C. or higher and a melting point of polyester of −20 ° C. for 1 to 20 seconds). The reason for this is that, after storing the wound resin film roll, when the resin film roll is coated on a heated metal plate, the resin film roll is wrinkled due to breakage of the resin film due to unwinding tension and shrinkage with time during storage of the resin film roll. This is because it is preferable to suppress blocking and the like.
[0024]
In the present invention, as the metal plate, a surface-treated steel plate such as tin-free steel, an aluminum plate, an aluminum alloy plate, an aluminum plate or an aluminum alloy plate subjected to surface treatment can be used. After heating these metal plates to a melting point of -20 ° C. or higher and a melting point of + 150 ° C. of polyester, the resin film (A) and the resin film (B) are simultaneously laminated or sequentially laminated on the metal plate using a laminating roll, and subsequently The laminated metal plate is heated at a melting point of polyester of + 10 ° C. or higher and a melting point of + 60 ° C., and then cooled with water and / or air to obtain a resin-coated metal plate. However, when laminating the resin film (A) on a metal plate, it is preferable to contact the (II) layer side with the metal plate in order to ensure canability.
[0025]
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 economy.
[0026]
【Example】
Hereinafter, the present invention will be described based on examples.
[Evaluation methods]
[0027]
(1) Melting point of polyester
After heating and melting the polyester composition at 300 ° C. for 5 minutes, 10 mg of a sample obtained by quenching with liquid nitrogen was used, and the temperature rising rate was 10 ° C./min using a differential scanning calorimeter (DSC) in a nitrogen stream. When the exothermic / endothermic curve (DSC curve) was measured, the peak temperature of the endothermic peak accompanying melting was defined as the melting point Tm (° C.).
[0028]
(2) Neck-in amount
Using the average value (Acm) of the T die outlet width (60 cm) and the resin film width after cooling and solidification (resin film width before cutting and removing both ends) measured at n = 3, The amount (cm) was determined. A neck-in amount of 5 cm or less was evaluated as practical.
Neck-in amount (cm) = 60-A
[0029]
(3) Method for producing resin-coated metal plate
Resin film (A) on one side of an aluminum alloy plate heated to 250 ° C. (3004 series alloy plate having a thickness of 0.26 mm), and a resin film (II) on the other side so that the layer (II) is in contact with the metal plate After laminating B) at the same time, it was heated at 275 ° C. and then quenched in water to produce a laminated aluminum plate.
[0030]
(4) Releasability between can inner surface resin and processing punch
A laminated aluminum plate was canned at n = 10, and the degree of buckling occurring at the upper part of the molded can was visually observed. Evaluation criteria were set as follows, and ○ was evaluated as practical.
○: No buckling at the can opening
Δ: Buckling occurred at about 1/3 of the circumference of the can opening
×: Buckling occurs at 1/3 or more of the circumference of the can opening
[0031]
(5) Scratch resistance of the outer surface of the can (longitudinal scratch on the outer surface of the can)
A laminated aluminum plate was canned at n = 10, and the degree of generation of scratches on the outer surface of the molded can body wall portion was visually observed. Evaluation criteria were set as follows, and ○ was evaluated as practical.
○: No scratch
Δ: Scratches occur in about 1/3 of the outer surface
×: Severe scratches occurred to 1/3 or more of the outer surface
[0032]
(6) Impact resistance
A 7 cm square sample is cut out from the center of the barrel wall of a can that was obtained by heating an aluminum laminate plate at 280 ° C. for 40 seconds and then quenching in water. A weight (600 g) having a tip diameter of 10 mm is 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% dilute hydrochloric acid (with the convex portion of the sample immersed), and the corrosive state of the convex portion was visually observed after 3 days. Evaluation criteria were set as follows, and ○ was evaluated as practical.
○: No protrusion corrosion
X: Corrosion of convex part
[0033]
(7) The degree of whitening of the outer surface of the can after hot water treatment
A can obtained by making an aluminum laminate plate was heated at 270 ° C. for 40 seconds and then rapidly quenched in water. After immersing this sample in warm water at 80 ° C. for 10 minutes, the outer surface of the can obtained by quenching in water was visually observed. Evaluation criteria were set as follows, and ○ was evaluated as practical.
○: Whitening is not noticeable
Δ: Clearly whitened, but the color of the aluminum alloy plate is visible
×: The color of the aluminum alloy plate is not visible due to whitening
[0034]
[Abbreviations and contents of polyester and olefin polymer used in Examples and Comparative Examples]
(1) PET: Polyethylene terephthalate
(2) PBT: Polybutylene terephthalate
(3) Polyester A: Copolyester of terephthalic acid / C36 dimer acid (molar ratio 90/10) and ethylene glycol
(4) Polyester B: Copolyester of terephthalic acid / C36 dimer acid (molar ratio 95/5) and ethylene glycol / 1,4 butanediol (molar ratio 30/70)
(5) Polyester C: Copolyester of terephthalic acid and ethylene glycol / cyclohexanedimethanol (mol% 70/30)
(6) Olefin: Tuffmer A-4085 (Mitsui Chemicals, trade name)
[0035]
[Example 1]
The resin film (A) (I) layer raw material PET / PBT = 40/60% by weight polyester, and the (II) layer raw material polyester A alone is melted at 280 ° C., and the raw material at both ends of the resin film (A). The olefin simple substance is melted at 250 ° C. and 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.) is used. , Cast into cooling rolls (circumferential speed 20m / min) in layers (distance 15cm from the T die to the ground point of the molten resin with the cooling rolls, forcibly blowing air at the center and both ends with separate devices) Then, both ends (5 cm on one side) are 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 12.5 μm). Obtain a resin film .
Also, PET / PBT = 40/60% by weight of polyester is melted at 280 ° C. as a raw material at the center of the resin film (B), and olefin is melted at 250 ° C. as a raw material at both ends of the resin film (B). , Using 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.), layered cooling rolls (circumferential speed 20 m / Min) cast (distance from the T die to the contact point of the molten resin with the cooling roll is 15cm, the center and both ends are forcibly blown with separate devices), then both ends (5cm on one side) Was removed by cutting, and a roll-shaped resin film having a thickness of 16 μm used for the resin film (B) was obtained.
[0036]
A resin film (A) is pressure-bonded to one side of a 3004 series aluminum alloy plate (thickness 0.26 mm) heated to 250 ° C. so that the (II) layer side is in contact with the aluminum alloy plate, and a resin film (B ) And heated to 275 ° C., and then quenched in water to obtain a laminated aluminum plate.
[0037]
A lubricant for molding was applied to the laminated aluminum plate thus obtained, and then 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. Next, 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.
[0038]
Melting point of polyester, neck-in amount during casting, can-making ability (can releasability of can inner surface resin film and punch and occurrence of scratches on can outer surface resin film), degree of whitening of can outer surface after hot water treatment, impact resistance Table 1 shows. The method of this example is a method for producing a resin-coated metal plate having a small neck-in amount and excellent in economic efficiency, and a metal can excellent in can manufacturing performance and 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 resulting resin-coated metal sheet.
[0039]
[Example 2]
The thickness used for the resin film (A) is 25 μm ((I) layer thickness 12.5 μm, (II) layer thickness 12) in the same manner as in Example 1 except that the material for the (II) layer of the resin film A is polyester B alone. 0.5 μm) roll-shaped resin film and 16 μm-thick roll-shaped resin film used for the resin film (B) were obtained.
[0040]
Next, a laminated aluminum plate was produced in the same manner as in Example 1, and canned to obtain a 350 ml size seamless can.
[0041]
Melting point of polyester, neck-in amount during casting, can-making ability (can releasability of can inner surface resin film and punch and occurrence of scratches on can outer surface resin film), degree of whitening of can outer surface after hot water treatment, impact resistance Table 1 shows. The method of this example is a method for producing a resin-coated metal plate having a small neck-in amount and excellent in economic efficiency, and a metal can excellent in can manufacturing performance and 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 resulting resin-coated metal sheet.
[0042]
[Example 3]
The thickness used for the resin film (A) is 25 μm in the same manner as in Example 1 except that the (II) layer raw material of the resin film A is 87% by weight of polyester B and 13% by weight of olefin. A roll-shaped resin film having a thickness of 16 μm and a roll-shaped resin film having a thickness of 5 μm and a (II) layer thickness of 12.5 μm) were obtained.
[0043]
Next, a laminated aluminum plate was produced in the same manner as in Example 1, and canned to obtain a 350 ml size seamless can.
[0044]
Melting point of polyester, neck-in amount during casting, can-making ability (can releasability of can inner surface resin film and punch and occurrence of scratches on can outer surface resin film), degree of whitening of can outer surface after hot water treatment, impact resistance Table 1 shows. The method of this example is a method for producing a resin-coated metal plate having a small neck-in amount and excellent in economic efficiency, and a metal can excellent in can manufacturing performance and 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 resulting resin-coated metal sheet.
[0045]
[Example 4]
(II) layer raw material of the resin film A is 50% by weight of polyester A and the polymer obtained by granulating both ends cut and removed before obtaining the resin film (A) in Example 1 is made 50% by weight. Is used in the same manner as in Example 1 for the roll-shaped resin film and the resin film (B) having a thickness of 25 μm ((I) layer thickness 12.5 μm, (II) layer thickness 12.5 μm) used for the resin film (A). A roll-shaped resin film having a thickness of 16 μm was obtained.
Next, a laminated aluminum plate was produced in the same manner as in Example 1, and canned to obtain a 350 ml size seamless can.
[0046]
Melting point of polyester, neck-in amount during casting, can-making ability (can releasability of can inner surface resin film and punch and occurrence of scratches on can outer surface resin film), degree of whitening of can outer surface after hot water treatment, impact resistance Table 1 shows. The method of this example is a method for producing a resin-coated metal plate having a small neck-in amount and excellent in economic efficiency, and a metal can excellent in can manufacturing performance and 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 resulting resin-coated metal sheet.
[0047]
[Example 5]
(II) layer raw material of the resin film A is 50% by weight of polyester A and the polymer obtained by granulating both ends cut and removed before obtaining the resin film (B) in Example 1 is made 50% by weight. Is used in the same manner as in Example 1 for the roll-shaped resin film and the resin film (B) having a thickness of 25 μm ((I) layer thickness 12.5 μm, (II) layer thickness 12.5 μm) used for the resin film (A). A roll-shaped resin film having a thickness of 16 μm was obtained. Next, a laminated aluminum plate was produced in the same manner as in Example 1, and canned to obtain a 350 ml size seamless can.
[0048]
Melting point of polyester, neck-in amount during casting, can-making ability (can releasability of can inner surface resin film and punch and occurrence of scratches on can outer surface resin film), degree of whitening of can outer surface after hot water treatment, impact resistance Table 1 shows. The method of this example is a method for producing a resin-coated metal plate having a small neck-in amount and excellent in economic efficiency, and a metal can excellent in can manufacturing performance and 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 resulting resin-coated metal sheet.
[0049]
[Comparative Example 1]
A roll-shaped resin film was obtained 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 changed to PET / PBT = 40/60% by weight. If the amount is large and both end portions are not cut and removed by 18 cm, a central portion with a uniform thickness distribution cannot be obtained.
[0050]
[Comparative Example 2]
Example except that PET / PBT = 20/80 wt% polyester as the raw material of the (I) layer of the resin film (A) and PET / PBT = 20/80 as the raw material of the central part of the resin film (B) However, since the resin film often breaks between the cooling roll and the take-up roll and a roll-shaped resin film cannot be obtained stably, it is not preferable as a method for producing a resin film.
[0051]
[Comparative Example 3]
Example except that PET / PBT = 70/30 wt% polyester as the raw material of the (I) layer of the resin film (A) and PET / PBT = 70/30 as the raw material of the central part of the resin film (B) The thickness used for the resin film (A) is 25 μm ((I) layer thickness 12.5 μm, (II) layer thickness 12.5 μm) and the thickness used for the resin film (B) is 16 μm. A roll-shaped resin film was obtained.
[0052]
Next, a laminated aluminum plate was produced in the same manner as in Example 1, and canned to obtain a 350 ml size seamless can.
[0053]
Melting point of polyester, neck-in amount during casting, can-making ability (can releasability of can inner surface resin film and punch and occurrence of scratches on can outer surface resin film), degree of whitening of can outer surface after hot water treatment, impact resistance Table 1 shows. This method is a method for producing a resin-coated metal plate having a small neck-in amount and excellent in economic efficiency, and was a method for producing a resin-coated metal plate having excellent can-making properties and impact resistance. Since whitening property is inferior, it is not preferable as a manufacturing method of a resin-coated metal sheet.
[0054]
[Comparative Example 4]
The thickness used for the resin film (A) is 25 μm in the same manner as in Example 1 except that the polyester film A is used as the raw material for the (I) and (II) layers of the resin film (A) (the (I) layer thickness is 12.5 μm). , (II) layer-shaped resin film having a 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.
[0055]
Melting point of polyester, neck-in amount during casting, can-making ability (can releasability of can inner surface resin film and punch and occurrence of scratches on can outer surface resin film), degree of whitening of can outer surface after hot water treatment, impact resistance Table 1 shows. This method was a method for producing a resin-coated metal plate with a small neck-in amount and excellent economic efficiency.However, since the resin on the inner surface of the can adheres to the processing punch and buckling occurs around the entire circumference, This is not preferable as a production method.
[0056]
[Comparative Example 5]
The thickness used for the resin film (A) is 25 μm ((I) layer thickness of 12) in the same manner as in Example 1 except that the material (II) of the resin film (A) and the material of the resin film (B) are polyester C alone. 0.5 μm, (II) layer thickness 12.5 μm) and a roll-shaped resin film having a thickness of 16 μm used for the resin film (B) were obtained.
[0057]
Next, a laminated aluminum plate was produced in the same manner as in Example 1, and canned to obtain a 350 ml size seamless can.
[0058]
Melting point of polyester, neck-in amount during casting, can-making ability (can releasability of can inner surface resin film and punch and occurrence of scratches on can outer surface resin film), degree of whitening of can outer surface after hot water treatment, impact resistance Table 1 shows. This method is a method for producing a resin-coated metal plate having a small neck-in amount and excellent in economic efficiency, and a method for producing a resin-coated metal plate having excellent hot water whitening resistance on the outer surface. Since the impact property is inferior, it is not preferable as a method for producing a resin-coated metal sheet.
[0059]
[Comparative Example 6]
A roll-shaped resin film was obtained in the same manner as in Example 1 except that 50% by weight of polyester / 50% by weight of olefin and PET / PBT = 40/60% by weight were used as raw materials for the (II) layer of the resin film (A). .
[0060]
Melting point of polyester, neck-in amount during casting, can-making ability (can releasability of can inner surface resin film and punch and occurrence of scratches on can outer surface resin film), degree of whitening of can outer surface after hot water treatment, impact resistance Table 1 shows. This method was a resin film production method having a small neck-in amount and excellent in economic efficiency, but because the resulting resin-coated metal plate is somewhat inferior in canability, it is preferable as a method for producing a resin-coated metal plate. Absent.
[0061]
[Table 1]

[0062]
【The invention's effect】
The method for producing a resin-coated metal sheet according to the present invention is not only an economical method because it eliminates waste of raw materials, but also has a can-making property (particularly, a mold inner surface resin film and a processing punch release property and a can. This is a manufacturing method for obtaining a resin-coated metal plate excellent in scratch resistance of the outer resin film. In addition, the hot water sterilization performed after filling the contents is unlikely to cause a bad appearance on the outer surface of the metal can (whitening of the resin film), and heating that assumes the outer surface baking coating performed for the purpose of beautification after the can is made. It can be said that this is a very useful method for producing a resin-coated metal plate, which is hardly reduced in impact resistance even if it is carried out.

Claims (3)

One surface to the melting point 180 ° C. or higher of the crystalline polyester resin coated film (A) composed mainly of other surface consisting of a melting point 180 ° C. or more crystalline polyester resin film of a metal plate (B) a resin which is coated A method for producing a coated metal plate, comprising:
The resin film (A) has a composite structure of (I) layer / (II) layer, the (I) layer is composed of 60:40 to 30:70 wt% of polyethylene terephthalate and polybutylene phthalate, and the (II) layer is Polyester and olefin polymer in which 50 mol% or more of all acid components are terephthalic acid residues and 5 to 50 mol% are aliphatic dicarboxylic acid residues having 10 or more carbon atoms are composed of 70:30 to 100: 0 wt%. , the resin film (B) is polyethylene terephthalate and polybutylene terephthalate 60: 40-30: all SANYO consisting 70 wt% of a polyester,
A step of obtaining a resin film (A) and a resin film (B) by cutting and removing both ends after cooling and solidifying the molten resin film obtained in a state in which the olefin polymer is merged at both ends using a T die ;
A method for producing a resin-coated metal plate, comprising a step of laminating a resin film (A) and a resin film (B) on a heated metal plate.   2. The resin-coated metal plate according to claim 1, wherein the olefinic polymer in both ends of the resin film (A), the (II) layer, and the olefinic polymer in both ends of the resin film (B) are the same. Manufacturing method.   The resin-coated metal sheet according to claim 1, wherein the blend ratio of the polyethylene terephthalate and the polybutylene terephthalate of the polyester of the resin film (A) and the resin film (B) is the same. Method.