JP3366205B2 - Polyester film for lamination of metal plate for can body and method for producing laminated metal plate for can body using the film - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a film useful as a constituent material for a film-laminated metal plate for a can body , and a method for producing a laminated metal plate using the film.

[0002]

2. Description of the Related Art Metal cans, which are a form of food and drink packaging containers, have excellent mechanical strength and excellent sealing property, so that the contents can be stored for a long time, and the contents can be filled at high temperature. Since it can be sealed as it is and can be easily sterilized such as retort treatment, it is highly reliable in terms of safety and hygiene as a packaging container. Furthermore, the contents can be stored in a heated state, and the can body after use can be stored. Since it has many advantages that it is relatively easy to separate and collect, in recent years, various kinds of contents are filled and used in large amounts.

On the inner and outer surfaces of the metal can for food and drink, while maintaining the flavor of the contents, at the same time preventing the corrosion of the material of the metal can, or improving the cosmetic appearance of the outer surface of the can and protecting the printing surface. As a conventional method, a solvent-based paint containing a thermosetting resin as a main component has been applied. However, such a paint can has the following problems. (A) When the contents are filled and sealed and then subjected to a heating treatment such as a retort treatment, low molecular weight substances such as residual solvent in the coating film migrate into the contents, and the flavor of the contents remarkably deteriorates.
(Inferior in flavor) (B) With the reduction in diameter of the can lid and the reduction in the thickness of the can, the workability and impact resistance of the coating film are required to be higher than ever, while the coating film is white after retort treatment. Retort resistance is required for problems such as deterioration and peeling of the coating film, but it is difficult to obtain a coating film that satisfies these performances at the same time. (C) A large amount of organic solvent is used, and a large amount of heat energy is required for drying and baking the coating film.

In contrast to such a coated can, recently, a metal can manufactured by using a film-laminated metal plate obtained by laminating a single-layer or multi-layer plastic film on a metal plate has attracted attention. In particular, polyester films have the advantages of excellent mechanical strength, processability, heat resistance, pinholes, cracks, etc., the flavor of the contents is not impaired (excellent flavor), and relatively inexpensive. Yes, it is being actively put into practical use.

As a method of laminating a plastic film on a metal plate, an adhesive layer is provided in advance on at least one of the plastic film and the metal plate and heat bonding is performed, or a metal plate using a heat-adhesive plastic film is used. There is a method of thermocompression bonding and. In the former method, when an adhesive consisting of a solution in which an uncured thermosetting resin is dissolved in an organic solvent is used, the problems (a) and (c) described above and the problem between the adhesive layer and the film Since an interface is generated in the laminate, the workability of the laminated metal plate and the impact resistance of the laminated can are difficult. On the other hand, when the latter method is used, the above problems (a) to (c) are solved and the productivity of metal cans is improved. For example, JP-A-2-305827, JP-A-3-86729, and JP-B-7-350.
92, JP-A-5-154971, JP-A-5
No. 156,040, JP-A No. 6-39979,
JP-A-7-207040 and JP-A-64-2253.
No. 0, JP-A-6-116374, Japanese Patent Publication No. 7-
80253, JP-A-5-147647, JP-A-7-195617, and JP-B-57-23584.
JP-A No. 60-170532, JP-A No. 3-212433, and JP-A No. 5-925 disclose polyester films capable of thermocompression bonding.
35, JP-A-3-57514, JP-A-3-
101930, JP-A-58-220729, JP-B-57-22750 and the like describe a method for producing a laminated metal plate and a metal can body having a high drawing ratio by using a thermocompression-bondable polyester film. Has been done.

By the way, the conventional polyester film for laminating a metal plate has other components for the purpose of maintaining thermocompression bonding property and for improving the workability of the laminated metal plate and maintaining the impact resistance of the metal can body. It has been made possible to lower the crystallinity of the film by copolymerizing or blending with. However, when a conventional polyester film for metal plate lamination is used, a low molecular weight substance in the film easily migrates to the contents during high temperature treatment such as retort treatment, and the flavor of the contents is impaired. Are various problems that phenomena such as discoloration of contents occur, film crystallization occurs during retort processing, film peeling, microcracks occur, or spherulites grow and the film whitens. Occurred, and improvement was required. Performance such as processability of laminated metal plate, increase impact resistance of laminated can (usually lowering crystallinity of film), improve flavor of metallic can (usually increase crystallinity of film), etc. It has been proposed to devise thermocompression bonding conditions in order to achieve a good balance (Japanese Patent Application Laid-Open No. 5-92535 and Japanese Patent Application Laid-Open No. 7-223).
No. 646, Japanese Patent Publication No. 7-115411, Japanese Patent Publication No. 7-85923, Japanese Patent Laid-Open No. 7-195651), the temperature of the steel plate, the heat roll, the laminating speed, etc. must be uniformly and accurately controlled. In addition, there is a problem that the apparatus and equipment become very expensive and the economy is lost.

The present inventors have already blended a polyethylene terephthalate (PET) type polyester resin having a specific intrinsic viscosity and a polybutylene terephthalate (PBT) type polyester resin having a specific intrinsic viscosity in a specific ratio. A film made of a polyester resin composition having a specific degree of plane orientation and thermal characteristics can be thermocompression-bonded to a metal plate even if the crystallinity is high, and the conditions for thermocompression-bonding to the metal plate It has been found that the quality of the laminated metal plate obtained by the fluctuation is hard to change (Japanese Patent Application No. 8).
-268988). Further, the laminated metal plate obtained by thermocompression-bonding the above film with the metal plate under a specific condition is capable of producing a high drawing ratio can even if the film maintains a high crystallinity, and is excellent in molding. Have the following characteristics:
Further, the metal can body obtained by using this laminated metal plate had excellent flavor property and impact resistance because the high crystallinity of the film was maintained.

However, even in the above epoch-making invention, the can diameter is 60 mm or less, and the body height is 100 mm.
In the case of producing a metal can body that exceeds the above, or in the case of further performing ironing after drawing, the adhesiveness between the film and the metal plate and the formability are not sufficient, and the film is not formed during the forming. However, there is a problem in that they may be peeled off or microcracks may be generated. Further, when increasing the crystallinity of the film by heat treatment to reduce the elution of oligomers from the laminated metal plate or metal can obtained using the film of the invention,
When crystallized abruptly or excessively, spherulites grow and the film is whitened, and there are problems such as peeling phenomenon of the film and generation of microcracks, and there has been a demand for improvement.

[0009]

SUMMARY OF THE INVENTION The main object of the present invention is to solve such problems at once and achieve the following objects (1) to (2). It has excellent mechanical properties and heat resistance, and even if it has a high crystallinity, it can be thermocompression bonded to a metal plate. Moreover, the quality of the laminated metal plate changes due to fluctuations in the conditions when thermocompression bonding to the metal plate. To provide a film for metal laminating that is difficult to remove and can be thermocompression bonded at a relatively low temperature. It has excellent moldability and various processability, and even if the film of the laminated metal plate or metal can body is crystallized after thermocompression bonding and various molding processes, the film is whitened, peeled off, microcracks, etc. (EN) Provided is a film for laminating a metal plate, which is free from the problem of occurrence and is therefore capable of easily producing a metal can body having excellent flavor and impact resistance. To provide a method for producing a laminated metal plate capable of sufficiently expressing the features of the film of the present invention.

[0010]

Means for Solving the Problems As a result of intensive studies for solving the above problems, the present inventors have found that PET having a specific intrinsic viscosity or a polyester (A) mainly composed of PET
And a polyester resin composition in which PBT having a specific intrinsic viscosity or a polyester (B) mainly composed of PBT is blended in a specific ratio to form a specific compatible state, and a specific degree of plane orientation is obtained. That the above problems can be solved by the film described above, and further, by laminating the film of the present invention with a metal plate under specific conditions, it is found that the above problems can be more effectively achieved. The invention was reached.

That is, the gist of the present invention is as follows. (1) Polyethylene terephthalate or ethylene terephthalate
Polyester (A) 10 to 60 wt% of the intrinsic viscosity of 0.50 to 0.90 mainly composed of tallates, intrinsic viscosity mainly of polybutylene terephthalate or butylene terephthalate is 0.60 or more polyester (B) 90 ~
A film composed of a polyester resin composition containing 40% by weight, wherein the film has a degree of plane orientation of 0.11.
Is 0.16, and the can body, characterized in that the thermal characteristics of the film satisfies the conditions of the following (a) ~ (d)
Polyester film for metal plate laminating. (A) Melting point derived from polyester (A) [Tm
(A)] is 228 to 245 ° C (excluding 245 ° C
Ku) . (B) Melting point [Tm derived from polyester (B)
(B)] is 190 to 218 ° C. (C) The sum of heats of fusion [ΔHm (A + B)] derived from the crystal parts of the polyesters (A) and (B) in the film is 3
3 to 45 J / g. (D) Melting point [Tm derived from polyester (A)
(A)] of the heat of fusion [ΔHm (A1)] observed above
The ratio to [ΔHm (A + B)] is 0.05 to 0.3. (2) Using the film of (1) above, the following formula (a)
After contacting a metal plate having a temperature T (° C) satisfying the above condition with an S (sec) film for a time satisfying the following formula (B), 50 ° C
A method for producing a film-laminated metal plate for a can body, which comprises cooling the film to a temperature not higher than the glass transition temperature at a speed of not less than / sec. (Tv−3 ° C.) ≦ T ≦ (Tv + 10 ° C.) (a) (30 / T) −0.11 ≦ S ≦ (200 / T) (b)

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below.

The polyester (A) used in the present invention is one obtained by melt-polycondensation reaction containing a terephthalic acid component and an ethylene glycol component as main components, or subsequently solid-phase polymerized, and has an intrinsic viscosity of 0.50 to 0.50. 0.
It is necessary to be 90, preferably 0.55
0.80, and more preferably 0.60 to 0.77. When the intrinsic viscosity is less than 0.50, a film having mechanical strength that can be put to practical use cannot be obtained, and when the intrinsic viscosity exceeds 0.90, the thermocompression bonding property of the film to the metal plate is deteriorated, which is not preferable. .

The polyester (A) may be obtained by appropriately copolymerizing other components as long as the effects of the present invention are not impaired. Examples of the acid component as a copolymerization component include aromatic dicarboxylic acids such as isophthalic acid, (anhydrous) phthalic acid, 2,6-naphthalenedicarboxylic acid, and 5-sodium sulfoisophthalic acid, oxalic acid, succinic acid, adipic acid, sebacine. Acids, azelaic acid, dodecanedicarboxylic acid, (anhydrous) maleic acid, fumaric acid, itaconic acid, citraconic acid, mesaconic acid and other aliphatic dicarboxylic acids, (anhydrous) hexahydrophthalic acid, hexahydroterephthalic acid and other alicyclic groups Dicarboxylic acids, dimer acids having 20 to 60 carbon atoms, hydroxycarboxylic acids such as p-hydroxybenzoic acid, lactic acid, β-hydroxybutyric acid, ε-caprolactone, (anhydrous) trimellitic acid, trimesic acid, (anhydrous) pyromellitic acid Mention may be made of polyfunctional carboxylic acids such as acids. As the alcohol component as a copolymerization component, diethylene glycol, triethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6- Hexanediol, neopentyl glycol, molecular weight 200-2
Of aliphatic diol such as polyethylene glycol, polypropylene glycol, polytetramethylene glycol, 1,4-cyclohexanedimethanol, 1,4-
Alicyclic diol such as cyclohexanediethanol, aromatic diol such as ethylene oxide or propylene oxide adduct of bisphenol A or bisphenol S,
Examples thereof include polyfunctional alcohols such as trimethylolpropane, glycerin, and pentaerythritol.

As a method for producing the polyester (A), a known method can be adopted. For example, a slurry of terephthalic acid, ethylene glycol and, if necessary, other copolymerization components is continuously supplied to an esterification reaction tank in which bis (β-hydroxyethyl) terephthalate and its low polymer are present, and the temperature is set to 250 ° C. The reaction is carried out at a temperature in the vicinity for about 3 to 8 hours to continuously obtain an esterified product having an esterification reaction rate of about 95%. Then, this was transferred to a polymerization vessel, and in the presence of a catalyst such as germanium dioxide or antimony trioxide, under a reduced pressure of 1.3 hPa or less and at a temperature of 250 to 280 ° C.
Then, the melt polycondensation reaction may be carried out until a polyester having a desired intrinsic viscosity is obtained. Further, the polyester obtained by the above method may be further solid-phase polymerized.

The polyester (B) in the present invention is one obtained by melt-polycondensation reaction of a terephthalic acid component and a 1,4-butanediol component as main components, or subsequently solid-phase polymerized, and has an intrinsic viscosity of 0. It is necessary to be 60 or more, and 0.80 to 2.0 is preferable. When the intrinsic viscosity is less than 0.60, it is not possible to obtain a film having mechanical strength that can be put to practical use. The upper limit of the intrinsic viscosity is not particularly limited, but it is preferably 2.0 or less from the viewpoint of the productivity of the raw material polyester resin and the film. Further, the polyester (B) may appropriately be copolymerized with other components similar to the polyester (A) as long as the effects of the present invention are not impaired.

As a method for producing the polyester (B), a known method can be adopted. For example, dimethyl terephthalate, 1,4-butanediol, and optionally other copolymerization components are charged into a transesterification reaction tank, and
The reaction is carried out at a temperature near 0 ° C. for about 5 hours to obtain a transesterification reaction product having a transesterification reaction rate of about 95%. Then, this was transferred to a polymerization vessel, and in the presence of a catalyst such as tetra-n-butyl titanate or tetraisopropyl titanate, under a reduced pressure of 1.3 hPa or less and at a temperature of 220 to 250 ° C.
Then, the melt polycondensation reaction may proceed until a polyester having a desired intrinsic viscosity is obtained. Further, the polyester obtained by the above method may be further solid-phase polymerized.

The blending ratio of the polyester resin composition in the present invention is 10 to 60% by weight of the polyester (A),
It is necessary to make the polyester (B) 90 to 40% by weight. 10% by weight of polyester (A)
In the case of less than, when the film is crystallized after melt thermocompression bonding and quenching with a metal plate, spherulites are likely to grow, whitening or peeling of the film or microcracks occur, or the melting curve of DSC. There is a problem that the valleys are not recognized, and the quality of the laminated metal plate is likely to fluctuate due to fluctuations in conditions when thermocompression bonding with the metal plate. Also,
When the blending ratio of the polyester (A) exceeds 60% by weight, the crystal part derived from the polyester (B) in the film is reduced, and the quality of the laminated metal plate is improved against the fluctuation of the conditions when thermocompression bonding with the metal plate. It becomes easy to change,
It is not possible to sufficiently increase the crystallinity of the film by performing crystallization treatment after thermocompression bonding with the metal plate, and the processability of the laminated metal plate is impaired.

The film of the present invention has a plane orientation degree f of 0.1.
Must be between 1 and 0.16. Here, f is defined by the following formula. f = {(nx + ny) / 2} -nz where nx and ny are the maximum and minimum values of the refractive index in the plane direction of the film, and nz represents the refractive index in the thickness direction of the film. When the degree of plane orientation is less than 0.11, the mechanical properties and heat resistance of the film are not sufficient, and when it exceeds 0.16, microcracks occur in the film during processing of laminated metal plates such as drawing and neck processing. It causes a problem of breaking or breaking.

In the film of the present invention, the melting point derived from polyester (A) is 228 to 245 ° C, and the melting point derived from polyester (B) is 190 to 218 ° C. The melting points of the polyester (A) and the polyester (B) change depending on the degree of compatibility of both components (including the degree of transesterification reaction), and when these values are less than the respective lower limits, The exchange reaction has proceeded too much, and the crystallinity of the film cannot be increased even if a crystallization treatment is performed, and the flavor property is impaired. On the other hand, when the melting point derived from both polymer components exceeds the above upper limit, respectively, the compatibility becomes insufficient, the thermocompression bonding property of the film and the adhesiveness to the metal plate, the processability is lowered, and the film When it is stretched, it easily breaks.

As the polyesters (A) and (B) used as the raw materials in the present invention, polyesters composed of various constituents can be used according to the purpose. Preferred melting points depending on the type of polyester are as follows. It is shown. (B) In the case of PET / PBT, Tm (A) = 235-2
45 ° C, Tm (B) = 205 to 218 ° C. (B) In the case of copolymerized PET / PBT, Tm (A) = 22
8-240 degreeC, Tm (B) = 200-218 degreeC. (C) In the case of PET / copolymerized PBT, Tm (A) = 23
0-245 ° C, Tm (B) = 190-213 ° C. (D) In the case of copolymerized PET / copolymerized PBT, Tm (A)
= 230-240 ° C, Tm (B) = 195-213 ° C.

Further, the film of the present invention has a sum of heats of fusion [Δ that originates from the crystal parts of polyesters (A) and (B).
Hm (A + B)] is required to be 33 to 45 J / g, and more preferably 38 to 45 J / g. ΔHm
When (A + B) is less than 33 J / g, the flavor property may be impaired, and when it exceeds 45 J / g, the thermocompression bonding property of the film and the adhesiveness with the metal plate are deteriorated, and the laminated metal plate is used as a can body. When processed into a film, microcracks may occur in the film, or the film and the metal may peel off.

In the film of the present invention, the ratio of the heat of fusion [ΔHm (A1)] to [ΔHm (A + B)] observed above the melting point [Tm (A)] derived from polyester (A) is 0.05. -0.3, preferably 0.05-0.
25, and more preferably 0.06 to 0.20.
When the above value is less than 0.05, the film is whitened, peeled off, or has microcracks, particularly when subjected to crystallization treatment after thermocompression bonding with a metal plate preheated to a temperature of Tm (B) or higher. May occur. The above value is 0.3
If the value exceeds [can height, can height] / (can diameter) is 1.5 or more, the film peels off at the top of the can body at the time of forming a metal can body or drawing and ironing. May occur.

The film of the present invention has a temperature of 20 ° C./mi.
When the temperature was raised by n, crystallization was not observed at a temperature of [Tm (B)] or lower, or even if crystallization occurred, the crystallization start temperature Tc was 150 ° C. or higher and the crystallization The heat (ΔHc) is preferably less than 5 J / g. If the above requirements are not satisfied, it may cause laminating failure due to the heat shrinkage phenomenon of the film during thermocompression bonding with the metal plate.

Further, in the film of the present invention, in the melting curve obtained by differential scanning calorimetry (DSC), [Tm (A)] and [Tm (B)] in the film are close to each other, so that some of them overlap each other. , DSC chart, a valley (see FIG. 1b) of the melting curve appears between Tm (A) and Tm (B). And this [Tm (A)]
And the heat of fusion ΔHm (Tv) observed at a temperature (Tv) located in the valley between [Tm (B)] and [Tm (B)] is [ΔHm (A +
B)] is preferably 30 to 70%. That is, ΔHm (Tv) is 30 to 7 of [ΔHm (A + B)].
By setting it to 0%, the adhesiveness between the film and the metal plate,
It is possible to obtain molding processability and quality stability of the laminated metal sheet against variations in conditions when thermocompression-bonding to the metal sheet. When the above value exceeds 70%, in order to stabilize the quality of the laminated metal plate against the fluctuation of conditions when thermocompressing the metal plate, the thermocompression bonding must be performed at a high temperature, and as a result, There may be a problem that the film surface after thermocompression bonding is warped. Further, when the above value is less than 30%, the adhesiveness with the metal plate and the moldability of the laminated metal plate may be deteriorated in an attempt to stabilize the quality of the laminated metal plate.

The film of the present invention has an acid value of the resin composition constituting the film of 35 equivalent / ton or less, preferably 3
When the amount is 0 equivalent / ton or less, more preferably 27 equivalent / ton or less, the flavor property is further improved.
Further, by setting the acid value to 35 equivalents / ton or less, the elution of low molecular weight substances such as oligomers in the film after the retort treatment can be significantly reduced. Examples of the method for adjusting the acid value to 35 equivalents / ton or less include a method using a resin having a low acid value as a raw material polyester, an alcohol compound and a carbodiimide when melt-mixing and extruding the polyester (A) and the polyester (B). A method of blocking at least a carboxyl group by adding at least one compound, an epoxy compound, an oxazoline compound or the like can be used.

The metal plate laminating film of the present invention comprises
It can be produced by a known method such as a flat type or a tubular type film forming method, but having a plane orientation degree of the film defined in the present invention, a flat type is used for producing a film having less thickness unevenness. The simultaneous biaxial stretching method is preferable as the stretching method.

When the film of the present invention is produced by the flat simultaneous biaxial stretching method, for example, a resin composition comprising polyester (A) and polyester (B) in a predetermined mixing ratio is provided with a T die. Using an extruder, temperature 2
It is melted at 30 to 280 ° C., extruded in a sheet form from a T-die, brought into close contact with a casting roll whose temperature is controlled at 40 ° C. or lower, and rapidly cooled to obtain an unstretched sheet having a desired thickness. In addition, in order to sufficiently mix the resin composition as a raw material, a raw material which has been melt-kneaded in advance may be used.

The melting and kneading temperature of the resin, the shear rate applied to the resin in the extruder, and the residence time in the extruder are [Tm
(A)], [Tm (B)], [ΔHm (A1)], [Δ
Hm (A + B)] and the like have a great influence. That is, as the melt-kneading temperature is higher, the shear rate is higher, and the residence time is longer, the melting point derived from each component is lowered, and the crystallinity and the ratio of [ΔHm (A1)] to [ΔHm (A + B)] are decreased. Will tend to decrease. In particular, when the residence time is long, the viscosity of the resin is lowered due to thermal decomposition or hydrolysis of the resin and oligomer formation is caused. Therefore, the residence time is preferably 20 minutes or less, more preferably 15 minutes or less. In order to promote the compatibilization of the polyesters (A) and (B), a method of adding an ester exchange catalyst at the time of melt kneading can be adopted. Examples of the transesterification catalyst include germanium dioxide, antimony trioxide, tetra-n-butyl titanate, tetraisopropyl titanate, zinc acetate, cobalt acetate, sodium acetate, manganese acetate and the like.

Next, both ends of the unstretched sheet are grasped by clips and preheated by blowing hot air of 40 to 100 ° C. from the upper and lower surfaces of the sheet, and 2 to 4 in the vertical and horizontal directions in an atmosphere of 50 to 120 ° C., respectively. Biaxially stretched about twice. After that, the relaxation rate in the longitudinal direction and / or the lateral direction is set to several percent, and 150 to
The film is heat-set at [Tm (B) -10] ° C for several seconds, heat-fixed, cooled to room temperature, and wound at a speed of 20 to 300 m / min to obtain a film having a desired thickness. If the stretching temperature is lower than 50 ° C, the stretching stress becomes high and necking occurs. If the stretching temperature exceeds 120 ° C, the film is melted or the film is crystallized to be whitened, and the plane orientation of the film is lowered.

As a heat treatment method after stretching, a conventionally known method can be adopted, for example, a method of blowing hot air to the stretched film, a method of irradiating the stretched film with infrared rays, or a method of irradiating the stretched film with microwaves. Examples of the method include a method in which hot air is blown onto the stretched film because it can be uniformly and accurately heated. Also,
Japanese Patent Publication No. 35-11774, Japanese Patent Publication No. 43-5557
As disclosed in Japanese Unexamined Patent Publication (Kokai), a heat buffer zone may be provided between the stretching step and the heat setting step.

The film of the present invention contains one or more kinds of average particle diameters selected from inorganic lubricants such as silica, alumina, kaolin, calcium carbonate, titanium dioxide and barium sulfate, or organic lubricants such as silicone particles. 2.
A slipperiness can be imparted to the film surface by adding a necessary amount of a lubricant having a thickness of 5 μm or less, and the process passability at the time of film production or thermocompression bonding with a metal plate can be improved. Further, titanium dioxide, barium sulfate, a silicone compound or the like may be added to impart a hiding property to improve the appearance of the metal can or the printability on the metal can. Further, the film may contain a colorant, an antioxidant, an antistatic agent, a defoaming agent, a flame retardant and the like.

The film of the present invention has a thickness of 5 to 100 μm.
m, preferably 10 to 50 μm, more preferably 10
Is about 25 μm. If the thickness is less than 5 μm, breakage or the like is likely to occur during processing, and if it exceeds 100 μm, the quality is excessive and uneconomical.

Further, the film of the present invention has the purpose of further improving the thermocompression bonding property with a metal plate and the subsequent adhesive property.
The adhesive layer can be provided by a coextrusion method, a laminating process, or a coating process. The dry thickness of the adhesive layer is preferably 0.5 μm or less.

Further, on the opposite surface (hereinafter, abbreviated as the opposite surface) of the film which is thermocompression-bonded to the metal plate, the appearance and printability of the metal can body are improved, and the heat resistance and retort resistance of the film are improved. For this purpose, one kind or two or more kinds of resin layers can be provided. These layers can be provided by a coextrusion method, laminating or coating.

As a method of laminating the film and the metal plate of the present invention, the metal plate is preheated to a predetermined temperature in advance, and the film and the film are pressure-contacted by a temperature-controllable roll and thermocompression-bonded, and then at room temperature. A method of cooling to is adopted, and this method can be carried out continuously. Examples of the heating method for the metal plate include a heater roll heat transfer method, an induction heating method, a resistance heating method, and a hot air transfer method.
Particularly, in consideration of equipment cost and simplification of equipment, the heater roll heat transfer method is preferable. As a cooling method after lamination, a method of immersing in a coolant such as water or a method of contacting with a cooling roll can be used.

In the present invention, thermocompression bonding can be performed even at a temperature below [Tm (B)] at which the crystal part of the film is not substantially destroyed, specifically at a relatively low temperature of 180 to 190 ° C., but a high drawing ratio. When drawing or drawing and ironing of the film, it is better to amorphize a part of the film to improve the adhesion between the film and the metal plate and the molding processability. The following thermocompression bonding conditions are preferable in order to prevent fluctuations in the quality of the laminated metal plate due to fluctuations in the conditions during pressure bonding. That is, after contacting a metal plate having a temperature T (° C.) satisfying the following formula (a) with a film S (sec) satisfying the following formula (b) for 50 ° C./s
Cool to below the glass transition temperature of the film at a rate of ec or higher. (Tv−3 ° C.) ≦ T ≦ (Tv + 10 ° C.) (a) (30 / T) −0.11 ≦ S ≦ (200 / T) (b)

As the metal plate used in the present invention, a sheet-shaped or strip-shaped steel plate and an aluminum plate, or those obtained by subjecting their surfaces to various plating treatments or chemical conversion treatments are preferable. In particular, a film having a hydrated chromium oxide film on the surface has excellent adhesion to the film. In particular, tin-free steel (TFS) having a two-layer structure in which the lower layer is metallic chromium and the upper layer is chromium hydrated oxide is preferable, and the steel plate surface is plated with one or more layers of tin, nickel, zinc, aluminum, etc. , Plated with alloy and having the above-mentioned two-layer structure film or chromium hydrate oxide film formed on it, aluminum is subjected to electrolytic chromic acid treatment, immersion chromic acid treatment, etc. The thing etc. which formed the oxidization film can be used.

By using the laminated metal plate obtained as described above, heat resistance is excellent, high temperature treatment such as retort treatment is possible, and pinholes, microcracks, and films can be formed even if severe processing treatment is applied. It is possible to manufacture a metal can body in which defects such as peeling are unlikely to occur and which is excellent in flavor. The metal can also includes a metal container that has been processed to a form that can be filled with food and drink and used, and a part thereof. In particular, when the film of the present invention is used as a can body member for a three-piece can (3P can) that is subjected to severe neck-in processing or a can body member for a two-piece can (2P can) manufactured by drawing and ironing. The excellent workability of the laminated metal plate is exhibited. In addition, JP-A-3-57514 and JP-A-3-1019
It is particularly suitable in the case of producing a can body having a body height of 10 cm or more, which is shown in Japanese Patent Publication No. 30-34, and which is substantially not subjected to ironing but only by drawing. The metal can body of the present invention is suitable for filling contents such as coffee, green tea and black tea due to its excellent retort resistance and flavor property.

When a can body is produced using the laminated metal sheet of the present invention, it is usually processed at a temperature of room temperature to (glass transition temperature of film + 30 ° C.), but if necessary, it is further processed. Heat treatment may be applied to promote crystallization of the film. For example, the glass transition temperature of the film or higher, [T
m (B) -20] ° C., heat treatment for several seconds to about 30 minutes causes crystallization to proceed, but this treatment step is performed by printing the outer surface of the body, drying the top coat, and baking in the subsequent processing steps. It can be substituted in the processing step.

[0041]

The film of the present invention is characterized in that the quality of the laminated metal plate does not easily fluctuate due to fluctuations in conditions during thermocompression bonding with the metal plate, especially fluctuations in temperature. The reason for this is as follows from the DSC analysis of the film. Can be explained as follows. That is, the film of the present invention is composed of two substantially incompatible resin compositions having different melting points, and shows a melting curve by DSC as shown in FIG. 1 (b).
Further, FIG. 2 shows that the heat of fusion [ΔHm (T)] [ΔHm (A +
B)] is shown. When the metal plate preheated to the temperature T and the film are thermocompression bonded, the temperature of the film continuously changes in the thickness direction, and therefore the crystal structure of the film continuously changes in the thickness direction. In order to improve the adhesiveness with a metal plate and the processability of laminated metal plate, it is advantageous to raise the thermocompression bonding temperature to break the crystal structure of the film. The problem that the surface of the film on the side opposite to the plate side is warped occurs. In particular, in the case of a film having a small thickness that is industrially used, in order to improve the adhesiveness with a metal plate and prevent the surface on the opposite side of the film from being roughened, the heat of fusion shown in FIG. It is necessary to make the slope of the ratio curve steep, and there is a problem that the thermocompression bonding conditions must be controlled excessively uniformly and accurately.

On the other hand, the film of the present invention is shown in FIG.
As shown in (b), it has a plateau region near Tv in which the ratio of the heat of fusion hardly fluctuates, and moreover, by using a highly crystalline PBT resin as the low melting point resin, It is considered that the above problem is solved because the curve of the ratio of heat of fusion has a large slope.

[0043]

EXAMPLES Next, the present invention will be described more specifically by way of examples. The analysis method and measurement method of each characteristic value used in Examples and Comparative Examples are as follows.

Intrinsic viscosity [η] of resin: phenol / 1,
It measured at 20 degreeC using the equal weight mixed solvent of 1,2,2-tetrachloroethane. (Unit is dl / g.)

Acid value of resin: Resin sample was o-cresol /
Chloroform (weight ratio 7/3) 90 to 100 ° C, 20
It was dissolved under the condition of a minute, and potentiometric titration was performed with an alkali. (Unit is equivalent / ton.)

Degree of plane orientation f of film: manufactured by Atago Optical Co.,
The refractive index was measured using an Abbe type refractometer and calculated by the above formula. The refractive index was measured at a temperature of 25 ° C. using a polarizing plate analyzer attached to the eyepiece side of an Abbe type refractometer, and using monochromatic light NaD ray, using methylene iodide as a mount solution. The width of the film used for the measurement was 20 cm, and 3 cm portions were measured from the center and both ends of the film, and the average value was taken as the plane orientation degree.

Thermal properties of the film: from the film, the laminated metal plate and the film in the metal can body to 10 to 10 respectively.
A 12 mg sample was taken and DSC manufactured by Perkin Elmer
It measured using -7. Melting point of film, Tc, ΔHc
Each characteristic value of 25 is 25 at the temperature rising rate of 20 ° C./min.
The temperature was raised to 280 ° C. The melting points derived from the polyesters (A) and (B) were the temperatures at the peak tops of the respective melting peaks. The crystallization start temperature Tc was the temperature at which the exothermic peak rises. Heats of fusion [ΔHm (A + B)] derived from crystal parts of polyesters (A) and (B), and [ΔHm (A1)], [Δ
For Hm (Tv)], the baseline was unclear due to the crystallization peak, and the melting phenomenon of the crystallized portion during the DSC measurement could not be separated. That is, the temperature is raised to 25 to 190 ° C. at a temperature rising rate of 20 ° C./min,
Immediately after reaching 190 ° C, the temperature is lowered to 25 ° C at a rate of 50 ° C / min. And after holding at 25 ℃ for 3 minutes,
Again, the temperature was raised to 280 ° C. at 20 ° C./min, and [ΔHm (A + B)] and [ΔHm (A
1)] and [ΔHm (Tv)] were obtained. An example of the DSC chart obtained under the above two temperature rising conditions is shown in FIGS.

Lamination property: The condition after lamination was visually evaluated according to the following criteria. ⊚: The film laminated with the metal has no defects such as scratches and wrinkles, and the good thermocompression bonding area is 98% of the total area.
that's all. ◯: The above portion is 80% or more and less than 98% of the total area. Δ: The above portion is 50% or more and less than 80% of the total area. X: The above portion is less than 50% of the total area.

Adhesiveness: The above-mentioned laminating property is ⊚ or ○.
A strip-shaped test piece having a width of 18 mm from the laminated metal plate determined to be (the end of the laminated metal plate is not laminated,
The laminated portion is ensured to be 8 cm or more). Next, on the film surface of this test piece,
Adhere an adhesive tape specified in JIS Z-1522, and use an autograph manufactured by Shimadzu Corporation to obtain 10 mm / nin.
A 180 ° peel test was performed at a speed of 1, and the peel strength was measured and used as an index of adhesiveness. ◯: The peel strength of 10 or more test pieces out of 11 is 30
The film breaks at 0 gf or more or 300 gf or more. Δ: Peel strength of 5 or more test pieces out of 11 is 300
The film breaks at gf or more or 300 gf or more. X: Seven or more test pieces having a peel strength of less than 300 gf.

Moldability of the can body: Moldability-1: After the can was molded using the laminated metal plate, the presence or absence of damage such as peeling, breakage, cracks, etc. of the film was observed visually and by a fluorescent microscope (80 times magnification). And evaluated according to the following criteria. ◯: Out of 100 cans, 95 or more were not damaged. Δ: 80 to 94 out of 100 cans were not damaged. X: Out of 100 cans, 21 or more have some damage. In addition, about Examples 11-12, the test piece of 17 cm x 12 cm in size is cut out from the obtained laminated metal plate, and the formability of a can is evaluated assuming the case where it is used for a can body member of a 3P can. As a simple method for
-Using the Erichsen tester according to -5400, 100 pieces of laminated metal plates are extruded from both sides twice to a depth of 5 mm (molding condition: C-1), and then the same damage as the above of the laminated metal plate is performed. Was evaluated according to the same criteria.

Moldability-2: For metal can bodies whose moldability was evaluated as ◯, 10 can bodies were filled with 1 wt% concentration of saline solution and heated at 80 ° C. for 24 hours. The occurrence of rust in the can was evaluated according to the following criteria. ◯: No rust is visually observed. Δ: Rust occurred on less than 5% of the surface area of the film that was in contact with saline. X: Rust occurred on 5% or more of the surface area of the film that was in contact with saline. In addition, in Examples 11 to 12, five laminated metal plates processed by an Erichsen tester were immersed in a 1 wt% saline solution in a stainless steel container for heat treatment, and evaluated in the same manner as above.

Formability-3: The film of each laminated metal plate was subjected to a predetermined crystallization treatment, and then the formability-2 was evaluated.

Retort resistance: A metal can or a laminated metal plate (Examples 11 to 12) was put in an autoclave (BS-325 manufactured by Tommy Seiko Co., Ltd.) and subjected to retort treatment in steam at 125 ° C. for 30 minutes to obtain a film. The appearance of water spots (white spots) and white powder (derived from the oligomer in the film) was visually observed and used as an index of retort resistance. ◯: Good. Δ: Water spots or white powder were found in less than 5% of the film surface area. X: Water spots or white powder were observed on 5% or more of the surface area of the film.

Flavor: A 2P can body was obtained under the following molding conditions C-2 and C-3. C-2: Using a drawing die and a punch, draw forming is performed in four steps at room temperature, and then trimming and necking flange processing are performed to obtain an outer diameter of 53 mm and a body height of 2 mm, 2P.
I got a can body. C-3: Using a drawing die and a punch, drawing was performed in two stages at 40 ° C. That is, a disk with a diameter of 150 mm is cut out from a laminated metal plate, and the inner diameter is 75 m in the first step.
m can body, and in the second step, a can body having an inner diameter of 53 mm was formed. Then, using an ironing punch and a die with diameters of 52 and 65 mm, the thickness of the metal plate of the body is 65 times that of the bottom metal plate.
Squeeze molding at 45 ° C so that the outer diameter becomes 53%, then trimming and necking flange processing are performed to obtain an outer diameter of 53
A 2P can body having a diameter of 100 mm and a body height of 100 mm was obtained.

Next, using the obtained 2P can body, after performing a predetermined crystallization treatment, 190 g of distilled water was filled, and a commercially available 202 diameter aluminum EO lid was wound and sealed,
Retort treatment was performed in the same manner as above. Next, after sufficiently cooling to room temperature, 50 panelists taste the contents and judge whether the smell, taste, etc. are the same as those of distilled water, and the results are evaluated according to the following criteria. It was used as an index. ○: Less than 10 people sensed the difference between the two. Δ: The number of people who sensed the difference between the two was 10 or more and less than 30. X: The number of people who sensed the difference between the two was 30 or more. In addition, about Examples 11-12, after processing with an Erichsen tester and performing a predetermined crystallization treatment, it was put in a stainless steel container together with 400 g of distilled water per one laminated metal plate, sealed, and then retort. The treatment was carried out and evaluated in the same manner as above.

Impact resistance: The body part of the 2P can obtained under the molding conditions C-2 and C-3 was subjected to a predetermined crystallization treatment, then filled with 190 g of a salt solution having a concentration of 1% by weight, and aluminum having a diameter of 202 was used. Ten cans sealed with an EO lid were dropped onto the floor of the polyvinyl chloride tile from a height of 50 cm. next,
After heating at 80 ° C. for 24 hours, the moldability-2 (state of rust generation) was evaluated. In addition, about Examples 11-12, after laminating, it is 1 from the roll-shaped laminated metal plate.
A 0 cm × 10 cm square plate was cut out, subjected to a predetermined crystallization treatment, kept horizontal, and a 300 g cubic weight was placed on the square plate to perform a drop test. Then, it was immersed in a saline solution having a concentration of 1% by weight in a stainless steel container and subjected to a heat treatment to evaluate the formability-2.

Amount of eluted oligomer: After filling 190 g of distilled water, the product was sealed with an aluminum EO lid and subjected to retort treatment. Next, after sufficiently cooling to room temperature, the content was taken out, water was distilled off, the obtained non-volatile matter was weighed, and the value obtained by dividing this by the film-covered area on the inner surface of the 2P can was the amount of eluted oligomer (μg / cm ² ) It was confirmed in advance that no non-volatile matter was eluted from the aluminum EO lid by the retort treatment.

Polyester (A) and polyester (B) used in Examples and Comparative Examples are as follows. Polyester (A) A-1: 0.05 wt% silica having an average particle size of 1.0 μm
A solid-state PET having [η] of 0.71 and an acid value of 19 containing. Melting point is 254 ° C. A-2: 5 mo of isophthalic acid (hereinafter abbreviated as IPA)
PET subjected to solid-state polymerization with [η] of 0.76 copolymerized with 1%. The acid value is 23 and the melting point is 245 ° C. A-3: Polyester A-1 and A-2 dry blended at an equal weight ratio. A-4: PET subjected to solid phase polymerization with [η] of 0.92.
The acid value is 15 and the melting point is 255 ° C. A-5: PE having [η] of 0.67 and subjected to solid phase polymerization
T. The acid value is 25 and the melting point is 255 ° C. A-6: PE having [η] of 0.72 and subjected to solid phase polymerization
T. The acid value is 38 and the melting point is 255 ° C. In addition, A-2 to A-6 have an average particle size of 1.
It contains 0.05% by weight of 0 μm silica.

Polyester (B) B-1: PBT subjected to solid phase polymerization with [η] of 1.12.
The acid value is 27 and the melting point is 222 ° C. B-2: 5 mol% of IPA was copolymerized, and [η] was 0.
PBT subjected to solid phase polymerization at 98. Acid value 28, melting point 2
17 ° C. B-3: PB manufactured by Mitsubishi Engineering Plastics
T, Novadour 5009AS. B-4: [η] is 0.56 and P is not subjected to solid phase polymerization
BT. The acid value is 38 and the melting point is 222 ° C.

Example 1 40 parts by weight of polyester A-1 and polyester B-
1 was dry-blended in a ratio of 60 parts by weight, and this was blended with a cylinder part 275 using an extruder equipped with a T-die (slow compression type single screw having a diameter of 75 mm and L / D of 45).
Discharge rate 450g / mi at temperature of ℃, T die part 265 ℃
It was extruded into a sheet with n. Then, set this to the surface temperature 1
It was brought into close contact with a casting roll adjusted to 8 ° C. and rapidly cooled to obtain an unstretched sheet having a thickness of 130 μm. The end portion of this unstretched sheet was gripped with a clip of a tenter type simultaneous biaxial stretching machine, and after running in a preheating zone of 60 ° C for 2 seconds, at a temperature of 80 ° C, MD (longitudinal direction) was tripled and TD (transverse direction). Direction) was simultaneously biaxially stretched at a magnification of 3.5 times (the stretching zone passed in 3 sec). Next, the relaxation rate of TD was set to 5%, followed by heat setting treatment at 200 ° C. for 4 seconds, cooling to room temperature, and winding at a speed of 50 m / min to obtain a film having a thickness of 13 μm. Slit the resulting film, width 2
A 0 cm roll-shaped film A was obtained. Next, various characteristics were evaluated using this film. The results obtained are shown in Table 1.

Examples 2 to 9 and Comparative Examples 1 to 7 Various polyester films were prepared in the same manner as in Example 1 except that the raw material polyester resin, the compounding ratio, and the film production conditions were changed as shown in Tables 1 and 2. B to I and K to Q were obtained. The performance of the obtained film is shown in Tables 1 and 2.

Example 10 30 parts by weight of polyester A-1 and polyester B-1
Was dry-blended at a ratio of 70 parts by weight and sodium acetate at 0.5 parts by weight, and extruded into a sheet at a temperature of the cylinder to the T-die of 265 ° C. and a discharge rate of 480 g / min. To obtain a film J. The characteristic values of the stretched film are shown in Table 1.

[0063]

[Table 1]

Comparative Example 8 40 parts by weight of polyester A-5 and polyester B-3
Dry blend at a ratio of 60 parts by weight, and
The T-die portion was extruded into a sheet at a temperature of 265 ° C. and a discharge rate of 500 g / min.
An unstretched sheet of 0 μm was obtained. This unstretched sheet is
After running in a preheating zone of 0 ° C. for 2 seconds, MD and TD were simultaneously biaxially stretched at a magnification of 3 times in an atmosphere of 80 ° C. (the stretching zone passed in 3 seconds). Next, TD
Was relaxed to 5% and heat-treated for 4 seconds in hot air at 110 ° C. to obtain a film R. The characteristic values of the stretched film are shown in Table 2.

Comparative Example 9 30 parts by weight of polyester A-5 and polyester B-3
Was dry-blended at a ratio of 70 parts by weight to obtain an unstretched sheet having a thickness of 200 μm in the same manner as in Comparative Example 8. This unstretched sheet was run in a preheating zone of 50 ° C. for 2 seconds, and then simultaneously biaxially stretched in an atmosphere of 70 ° C. at a magnification of 3 times in MD and 3.5 times in TD (stretching zone was 3 seconds. Passing). Next, the relaxation rate of TD was set to 5%, and heat setting treatment was performed for 3 seconds in hot air at 195 ° C. to obtain a film S.
The characteristic values of the stretched film are shown in Table 2.

[0066]

[Table 2]

Comparative Example 10 An attempt was made to produce a film in the same manner as in Example 1 except that polyester B-4 was used as the polyester (B). However, the film was frequently broken during the stretching-heat setting steps, and However, a film having satisfactory mechanical properties could not be obtained.

Example 11 A tin-plated roll-shaped tin plate (steel-1) having a plate thickness of 0.20 mm and a plate width of 22 cm was heated to 226 ° C. with an induction heating roll, and obtained on both sides in Example 1. The roll-shaped film A having a width of 20 cm is applied to the surface temperature 100
Using a pair of silicone rolls adjusted to ° C, the laminate was laminated under the conditions of a nip length of 20 mm and a line speed of 20 m / min, and after 1 sec, it was immersed in ice water and cooled to obtain a laminated metal plate (lamination condition: L -1). In addition, it was confirmed that the laminated metal plate was cooled to 20 ° C. or lower after being immersed in ice water for 2 seconds. The obtained laminated metal plate was molded under molding conditions C-1, and then treated in an oven at 80 ° C for 5 minutes for crystallization (crystallization conditions: R-1). The properties of the obtained laminated metal plate are shown in Table 3.

Example 12 Using the film C, a laminated metal plate and each treated metal piece were obtained in the same manner as in Example 11. Table 3 shows the characteristic values and the performance evaluation results.

Example 13 A roll-shaped TFS (steel-2) having a plate thickness of 0.24 mm, a plate width of 22 cm and a temper degree of T-4 was heated to 233 ° C. by an induction heating roll, and the surface temperature of the silicone roll was 120 ° C. Example 11 except that the film B was used as
A laminated metal plate was obtained in the same manner as in (Lamination condition: L-2). Next, using a drawing die and a punch, the above-mentioned laminated metal plate was drawn at four stages at room temperature, and then trimmed and necked flanged to give a 2P can body with an outer diameter of 53 mm and a body height of 100 mm. Obtained (molding condition: C-2). Next, the obtained metal can was crystallized under the condition of R-1. Table 3 shows the performance of the obtained laminated metal plate and metal can body.

Examples 14 to 24 and Comparative Examples 11 to 16 Laminated metal plate and metal can in the same manner as in Example 13 except that the film composition, the type of metal plate, the laminating conditions, the molding conditions and the crystallization conditions were changed. Manufactured body. The properties of the obtained laminated metal plate and metal can body are shown in Tables 3 and 4.

The abbreviations in the table mean the following. Aluminum: 3004H19 material, thickness 0.26 mm, width 2
2 cm, phosphoric acid-chromate system chemical conversion product. Steel-3: A roll-shaped TFS having a plate thickness of 0.32 mm, a plate width of 22 cm, and a temper degree of T-1. Crystallization condition R-2: After standing still in an oven at 80 ° C. for 3 minutes, it was further held in an oven at 100 ° C. for 5 minutes.

[0073]

[Table 3]

[0074]

[Table 4]

Comparative Example 17 Using the film R and Steel-2, an attempt was made to carry out thermocompression bonding in the same manner as in Example 11, but since the film contracted immediately before contact with the metal plate, a good laminated metal plate could not be obtained. It was

Examples 25 to 26 and Comparative Examples 18 to 19 Using various films and Steel-2, an attempt was made to perform thermocompression bonding by changing the surface temperature of the metal plate during preheating according to the laminating condition L-2. By obtaining the following characteristic values, the change in the characteristics of the laminated metal sheet with respect to the change in conditions during thermocompression bonding was evaluated. The results obtained are shown in Table 5. T1: The minimum temperature of the metal plate surface temperature at which the evaluation of the formability-1 becomes O when the forming is performed under the condition of C-2. T2: The minimum temperature of the metal plate surface temperature at which the evaluation of the moldability-1 becomes O when the molding is performed under the condition of C-3. T3: Maximum temperature of the metal plate surface temperature where the film surface is not present during thermocompression bonding.

[0077]

[Table 5]

Example 27 A film T was obtained in the same manner as in Example 2 except that Polyester A-6 was used. The characteristics of the obtained film are shown in Table 6.

Example 28 N- based on 100 parts by weight of the polyester resin composition
A film U was obtained in the same manner as in Example 2 except that 0.2 part by weight of (2,3-epoxypropyl) phthalimide was added to obtain an unstretched sheet. The characteristics of the obtained film are shown in Table 6.

[0080]

[Table 6]

Examples 29 to 31 Films B, T and U were processed in the same manner as in Example 13 to obtain a 2P can body. Table 7 shows the results of evaluation of flavor and oligomer elution amount using the obtained metal can. Regarding the flavor property (2) in the table, after the retort treatment, a metal can sealed with distilled water was further added.
It is the result of evaluating the flavor property after storage at 3 ° C for 3 months.

[0082]

[Table 7]

[0083]

According to the present invention, the mechanical properties and heat resistance are excellent, and thermocompression bonding with a metal plate is possible even at a relatively low temperature. It is possible to provide a film for laminating a metal plate for a can body , which does not easily change the quality of the laminated metal plate even if it fluctuates, and is particularly excellent in moldability and various processability. And, even if the film of the laminated metal plate or the metal can body is subjected to the crystallization treatment, there is no problem that the film is whitened, peeling, microcracks, etc. occur, and the metal can is excellent in flavor property and impact resistance. The body can be easily manufactured. In addition,
As a method of making a part of the film amorphous when thermocompression-bonding the film to the metal plate and preventing the quality of the laminated metal plate from changing as much as possible due to changes in conditions during thermocompression bonding, Japanese Patent Publication No. 7-84532. Japanese Patent Laid-Open No. 7-90009
No. 3, JP-A-7-207039, JP-A-7-
As disclosed in JP-A-285206 and JP-A-7-290665, there is a method of using a multilayer film in which a resin layer having a low melting point is arranged in the adhesive layer on the metal plate side.
Interfacial peeling is likely to occur due to stress concentration between the film layers, and there is also a problem in terms of equipment cost and recycling, the single-layer film of the present invention does not have such a problem that the multilayer film has, It has an extremely high industrial utility value.

[Brief description of drawings]

FIG. 1 (a): D of a film composed of a resin of a single composition
It is a schematic representation of the melting phenomenon seen in the SC chart. (B): A schematic representation of the melting phenomenon seen in the DSC chart of a film made of a resin of two components that are essentially incompatible and have different melting points as in the present invention.

2 (a): In the case of FIG. 1 (a), the heat of fusion [ΔHm (T)] generated until reaching the temperature T, the heat of fusion [ΔHm (A) derived from the polyester (A)] ] It is the figure showing the value with respect to. (B): In the case of FIG. 1 (b), the heat of fusion [ΔHm (T)] generated before reaching the temperature T is derived from the polyesters (A) and (B) [ΔHm (A +
It is a figure showing the value for B)].

FIG. 3 is an example of a DSC chart obtained by increasing the temperature from 25 to 280 ° C. at a temperature increasing rate of 20 ° C./min.

FIG. 4 shows a temperature rising rate from 25 to 190 ° C. at a temperature rising rate of 20 ° C./min, and when the temperature reaches 190 ° C., 50 ° C./mi
The temperature is lowered to 25 ° C. at a rate of n. And 3 mi at 25 ° C
In the DSC chart obtained by raising the temperature to 280 ° C. again at 20 ° C./min after holding n, [ΔHm
(A + B)] is a diagram in which a portion corresponding to [A + B]] is hatched.

5 is a graph of [ΔHm (A
1]] is a diagram in which a portion corresponding to [1]] is hatched.

6 is a graph of [ΔHm (T
v)] is a diagram indicated by hatching.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁷ Identification code FI B29L 7:00 B29L 7:00 C08L 67:02 C08L 67:02 (72) Inventor Kiyomi Hata 23 Uji Kozakura, Uji City, Kyoto 23 Unitika Stock Central Research Laboratory (72) Inventor Yoshihiro Umemura 23 Uji Kozakura, Uji City, Kyoto Unitika Central Research Laboratory (56) Reference JP-A-7-145252 (JP, A) JP-A-5-331302 (JP, A) ) JP 5-186613 (JP, A) JP 5-186612 (JP, A) JP 51-90346 (JP, A) JP 3247053 (JP, B2) (58) Fields investigated (Int. Cl. ⁷ , DB name) C08J 5/18 B29C 55/16 B32B 15/08 C08L 67/02

Claims (5)

(57) [Claims] 1. Polyethylene terephthalate or ethylene
The intrinsic viscosity of terephthalate is 0.50
Polyester consisting of 0.9 to 60% by weight of polyester (A) and 90 to 40% by weight of polyester (B) mainly composed of polybutylene terephthalate or butylene terephthalate and having an intrinsic viscosity of 0.60 or more. A film composed of a resin composition, the degree of plane orientation of the film is 0.11 to 0.16, and the thermal characteristics of the film satisfy the following conditions (a) to (d) : A polyester film for laminating metal plates for can bodies characterized by: (A) Melting point [Tm derived from polyester (A)
(A)] is 228 to 245 ° C (excluding 245 ° C
Ku) . (B) Melting point [Tm derived from polyester (B)
(B)] is 190 to 218 ° C. (C) The sum of heats of fusion [ΔHm (A + B)] derived from the crystal parts of the polyesters (A) and (B) in the film is 3
3 to 45 J / g. (D) Melting point [Tm derived from polyester (A)
(A)] of the heat of fusion [ΔHm (A1)] observed above
The ratio to [ΔHm (A + B)] is 0.05 to 0.3. 2. The polyester film for a metal plate laminate for a can body according to claim 1, wherein the thermal properties of the film satisfy the following condition (e) . (E) 20 ° C /
No crystallization was observed at a temperature of [Tm (B)] or lower when the temperature was raised by min, or even if crystallization occurred, the crystallization start temperature Tc was 150 ° C. or higher and the crystallization Heat (ΔHc) is less than 5 J / g. 3. Differential scanning calorimetry (DSC) of the film
[Tm (A)] and [Tm (A)] in the melting curve obtained in
3. The heat of fusion ΔHm (Tv) observed below the temperature (Tv) located in the middle valley of (B)] is 30 to 70% of [ΔHm (A + B)]. Polyester film for laminating metal plates for can bodies . 4. The acid value of the resin composition constituting the film is 35 equivalents / ton or less.
3. A polyester film for laminating a metal plate for a can body according to any one of 3 above. 5. Using the polyester film for laminating a metal plate according to claim 1, a metal plate having a temperature T (° C.) satisfying the following formula (a) is represented by the following formula (b):
After contacting the S (sec) film for a time that satisfies
A method for producing a film-laminated metal plate for a can body, which comprises cooling the film to a glass transition temperature or lower at a rate of 50 ° C./sec or more. (Tv−3 ° C.) ≦ T ≦ (Tv + 10 ° C.) (a) (30 / T) −0.11 ≦ S ≦ (200 / T) (b)