JP3484999B2 - Manufacturing method of laminated metal sheet - 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 laminated metal plate for containers. More specifically, it is excellent in moldability, impact resistance, taste characteristics, and retort whitening resistance, and is a method for producing a laminated metal plate suitable for the material of a lid or body of a metal can produced by a forming process such as drawing or ironing. It is about.

[0002]

2. Description of the Related Art Conventionally, for the purpose of preventing corrosion, the inner and outer surfaces of metal cans are coated with various thermosetting resins such as epoxy or phenol dissolved or dispersed in a solvent to coat the metal surface. It has been widely practiced. However, such a coating method of a thermosetting resin has a problem that it takes a long time to dry the coating material, productivity is lowered, and environmental pollution is caused by a large amount of organic solvent.

As a method of solving these problems, there is a method of laminating a film on a metal plate which is a material of a metal can, a metal plate such as an aluminum plate, or a metal plate which has been subjected to various surface treatments such as plating on the metal plate. . When a metal can is manufactured by drawing or ironing a laminated metal plate of a film, the film is required to have the following characteristics. (1) Excellent adhesion between the film and the metal plate. (2) It has excellent moldability and does not cause defects such as pinholes after molding. (3) The film is not peeled off, and cracks and pinholes are not generated by the impact on the metal can. (4) The scent component of the contents of the can is adsorbed on the film,
The flavor of the contents should not be impaired by the odor of the film (hereinafter referred to as taste characteristics). (5) The film does not turn white when exposed to heat after drawing or lid molding, for printing or curing of the sealant, or in the steam sterilization process after filling the contents (retort whitening resistance). .

Many proposals have been made in order to solve these requirements. For example, Japanese Patent Application Laid-Open No. 64-22530 discloses a polyester film for metal plate lamination having a specific density and a plane orientation coefficient, and Japanese Patent Application Laid-Open No. Japanese Patent No. 57339 discloses a copolyester film for laminating metal plates having a specific crystallinity. However, these proposals are not ones that can comprehensively satisfy the various required characteristics as described above, and can be said to be at a sufficiently satisfactory level particularly in applications where high moldability and excellent taste characteristics are required. There wasn't.

Further, Japanese Patent Application Laid-Open No. 9-155969 discloses a polyester film for laminating metal plates, which has a specific structure. Although this proposal solves a wide range of required properties to some extent, it deteriorates adhesion and whitens the film appearance due to the molding process heat when molding into cans, the heating process after molding, and the high temperature sterilization process after filling the contents. However, there is a problem that workability is deteriorated.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the above-mentioned problems of the prior art, and to provide a laminated metal sheet excellent in moldability, heat resistance, impact resistance, taste characteristics and whitening resistance. Manufacturing method, in particular, moldability, impact resistance, taste characteristics, manufactured by molding processing such as drawing and ironing,
An object of the present invention is to provide a method for producing a laminated metal plate suitable for a material of a metal can having excellent retort whitening resistance.

[0007]

The above-mentioned object of the present invention can be achieved by the following means.

(1) Amorphous Young's modulus is 120 to 220 kg
When a biaxially stretched polyester film having a thickness of 1 / mm ² is laminated on at least one side of a metal plate, the temperature T ₀ of the metal plate at the start of lamination is equal to or higher than the melting point T _f of the film, and the temperature of the metal plate on the exit side of the laminating roll nip. A method for producing a laminated metal plate, which comprises laminating T ₁ at a melting point T _f of the film or less and further setting a laminating index K defined by the following formula within a range of 1 to 20 msec. K = (T ₀ −T _f ) × t / (T ₀ −T ₁ ), where t: nip time

(2) Amorphous Young's modulus is 140 to 200 kg
/ Mm²Biaxially stretched polyester film is a metal plate
Temperature of the metal plate at the start of lamination
Degree T ₀Is the melting point T of the film_fAbove, the laminating roll
Temperature T of the metal plate on the outlet side₁Is the melting point T of the film_fThe following
In addition, the laminate index defined by
Laminate the box K within the range of 1 to 20 msec.
A method for producing a laminated metal plate, comprising: K = (T₀-T_f) × t / (T₀-T₁) However, t: nip time

(3) When laminating a biaxially stretched polyester film in which 95 mol% or more of the polyester units constituting the film are ethylene terephthalate units on a metal plate, the temperature T ₀ of the metal plate at the start of lamination is adjusted to the film temperature. melting point T _f above, as well as the temperature T ₁ of the metal plate of the lamination roll nip exit-side below the melting point T _f of the film, it is laminated to a laminate index K which is defined further by the following formula in the range of 1~20msec A method for manufacturing a laminated metal plate, comprising: K = (T ₀ −T _f ) × t / (T ₀ −T ₁ ), where t: nip time

(4) When laminating a biaxially stretched polyester film having an amorphous Young's modulus of 120 to 220 kg / mm ² on the metal plate, 95 mol% or more of the polyester units constituting the film are ethylene terephthalate units. The temperature T ₀ of the metal plate at the start of lamination is set to the melting point T _f of the film or more, and the temperature T ₁ of the metal plate on the exit side of the laminating roll nip is set to the melting point T _f or less of the film.
Furthermore, the lamination index K defined by the following formula is 1 to
A method for producing a laminated metal plate, which comprises laminating within a range of 20 msec. K = (T ₀ −T _f ) × t / (T ₀ −T ₁ ), where t: nip time

(5) When laminating a biaxially stretched polyester film having an amorphous Young's modulus of 140 to 200 kg / mm ² on the metal plate, 95 mol% or more of the polyester units constituting the film are ethylene terephthalate units. The temperature T ₀ of the metal plate at the start of lamination is set to the melting point T _f of the film or more, and the temperature T ₁ of the metal plate on the exit side of the laminating roll nip is set to the melting point T _f or less of the film.
Furthermore, the lamination index K defined by the following formula is 1 to
A method for producing a laminated metal plate, which comprises laminating within a range of 20 msec. K = (T ₀ −T _f ) × t / (T ₀ −T ₁ ), where t: nip time

(6) A method for producing a laminated metal plate according to any one of (1) to (5) above, wherein the nip time t is in the range of 0.005 to 0.05 sec.

(7) In the above (1) to (6), the film is composed of at least two layers and the difference in intrinsic viscosity between the non-laminated surface and the laminated surface is 0.01 to 0.5.
The method for producing a laminated metal plate according to claim 1.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION As a result of intensive studies, the present invention has revealed that a film having a controlled amorphous Young's modulus due to an amorphous component of the film is used to control the thermal history of the laminate, thereby making Formability, even after processing and heating history
It is based on the finding that a laminated steel sheet having good taste characteristics and particularly excellent impact resistance and whitening resistance can be obtained.

The present invention will be described in detail below.
The polyester used in the present invention is a polymer composed of a dicarboxylic acid component and a glycol component, and examples of the dicarboxylic acid component include terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, diphenyldicarboxylic acid, diphenylsulfonedicarboxylic acid, diphenoxyethanedicarboxylic acid. Acids, aromatic dicarboxylic acids such as 5-sodium sulfoisophthalic acid, phthalic acid, oxalic acid, succinic acid, adipic acid, sebacic acid, dimer acid, maleic acid, fumaric acid and other aliphatic dicarboxylic acids, cyclohexyne dicarboxylic acid, etc. Alicyclic dicarboxylic acid, oxycarboxylic acid such as p-oxybenzoic acid, and the like. Among these dicarboxylic acid components, terephthalic acid and isophthalic acid are preferable in terms of heat resistance and taste characteristics.

On the other hand, examples of the glycol component include ethylene glycol, propanediol, butanediol,
Examples thereof include aliphatic glycols such as pentanediol, hexanediol and neopentyl glycol, alicyclic glycols such as cyclohexanedimethanol, and aromatic glycols such as bisphenol A and bisphenol S. Among these, ethylene glycol is preferable among these glycol components. Two or more kinds of these dicarboxylic acid components and glycol components may be used in combination.

Further, a polyfunctional compound such as trimellitic acid, trimesic acid and trimethylolpropane may be copolymerized as long as the effects of the present invention are not impaired.

In the present invention, in terms of heat resistance and taste characteristics,
The amount of the metal element of the metal compound arbitrarily selected from the antimony compound, the germanium compound and the titanium compound contained in the polyester is 0.01 ppm or more and 1000 pp.
It is preferably less than m, more preferably 0.0
5 ppm or more and less than 800 ppm, particularly preferably 0.1
It is not less than ppm and less than 500 ppm.

It is preferable that a germanium compound is mainly contained because the taste characteristics after being subjected to a high-temperature heat history such as drying and retort treatment in a can-making process become good. Further, mainly containing an antimony compound is preferable because the amount of by-produced diethylene glycol can be reduced and the heat resistance can be improved. Further, a phosphorus compound is used as a heat stabilizer in 10
-200 ppm, preferably 15-100 ppm may be added. Examples of the phosphorus compound include phosphoric acid and phosphorous acid compounds, but are not particularly limited.

The polyester used in the present invention preferably has an amount of diethylene glycol component of 0.01 to 3.0% by weight, more preferably 0.02 to 2.5% by weight, and particularly preferably 0.1 to 2.0% by weight. % Is desirable in order to maintain good impact resistance even if it is subjected to a good moldability in the can making process, or a lot of heat history such as heat treatment in the can making process and retort treatment after the can making. By this, 200 ℃
It is considered that the above resistance to oxidative decomposition is improved, and 0.0001 to 1% by weight of a known antioxidant may be further added.

In order to improve the taste characteristics, the content of acetaldehyde in the film is preferably 30 ppm.
The following is more preferable, 25 ppm or less is more preferable, and 20 ppm or less is particularly preferable. If the content of acetaldehyde exceeds 30 ppm, the taste characteristics are poor. The method for controlling the content of acetaldehyde in the film to 30 ppm or less is not particularly limited, but for example, in order to remove acetaldehyde generated by thermal decomposition when the polyester is produced by a polycondensation reaction or the like, the polyester is reduced in pressure or A method of heat-treating at a temperature not higher than the melting point of polyester in an inert gas atmosphere, preferably 150 under reduced pressure or in an inert gas atmosphere.
A method of solid-state polymerization at a temperature of ℃ or more and a melting point or less, a method of melt-extruding using a vent-type extruder, an extrusion temperature at the time of melt-extruding a polymer is within a melting point of the high-melting polymer side + 30 ° C., preferably a melting point A method of extruding at + 25 ° C. within a short time, preferably within an average residence time of 1 hour, can be mentioned.

From the viewpoint of taste characteristics, the polyester used in the present invention preferably has an oligomer content of 1.0% by weight or less, more preferably 0.8% by weight or less, and more preferably 0.8% by weight or less. Is preferably 0.7% by weight or less. If the oligomer content in the polyester exceeds 1.0% by weight, the taste characteristics are inferior, which is not preferable. The method for controlling the oligomer content in the polyester to 1.0% by weight or less is not particularly limited, but can be achieved by adopting the same method as the method for reducing the acetaldehyde content in the polyester described above. .

The polyester used in the present invention is preferably a polyester containing ethylene terephthalate as a main constituent, a polyester in which 95 mol% or more of the repeating unit is ethylene terephthalate, and more preferably 97 mol% or more is particularly preferable. It is also desirable from the viewpoint of improving the characteristics. The polyester preferably has a melting point of 240 ° C. or higher, more preferably 245 ° C. or higher, and particularly preferably 250 ° C. or higher in view of heat resistance, taste characteristics, aging resistance and the like.

In the present invention, in order to improve impact resistance and taste characteristics, the intrinsic viscosity of the polyester is preferably 0.5 or more and 1.0 or less, more preferably 0.6 or more. It is considered that when the intrinsic viscosity is 1.0 or less, particularly preferably 0.7 or more and 1.0 or less, the entanglement density of polymer molecular chains is increased, but impact resistance and taste characteristics can be further improved. preferable.

Further, in order to improve the handleability and processability of the film used in the present invention, the average particle size is 0.1 to 1
It is preferable that 0.01 to 10% by weight of particles arbitrarily selected from 0 μm known internal particles, external particles such as inorganic particles and / or organic particles are contained,
Further, it is preferable that the inner particles having an average particle diameter of 0.1 to 5 μm, the inorganic particles and / or the organic particles are contained in an amount of 0.01 to 3% by weight.

As a method of depositing the internal particles, a known technique can be adopted. For example, JP-A-48-61556,
JP-A-51-12860, JP-A-53-4135
The techniques described in Japanese Patent Laid-Open No. 5 and Japanese Patent Laid-Open No. 54-90397 are cited. Further, it can be used in combination with other particles such as JP-A-59-204617. 10
It is not preferable to use particles having an average particle size of more than μm because defects in the film are likely to occur.

The inorganic particles and / or organic particles include, for example, wet and dry silica, colloidal silica,
Examples thereof include inorganic particles such as titanium oxide, calcium carbonate, calcium phosphate, barium sulfate, alumina, mica, kaolin and clay, and organic particles having styrene, silicone, acrylic acid and the like as a constituent component. Among them, inorganic particles such as wet and dry colloidal silica and alumina, and organic particles having styrene, silicone, acrylic acid, methacrylic acid, polyester, divinylbenzene and the like as constituent components can be mentioned. These internal particles, inorganic particles and / or organic particles may be used in combination of two or more kinds.

The biaxially stretched polyester film used in the present invention has a monolayer structure and an A layer / B layer structure.
Layer, B layer / A layer / B layer or A layer / B layer / C layer
It may have a layered structure of a layer, or more than three layers.

When the film is composed of a laminated biaxially stretched polyester film having at least two layers, the difference in intrinsic viscosity between the non-laminated surface and the laminated surface is 0.01 to 0.5. It is also preferable from the viewpoint of exhibiting excellent laminating characteristics, impact resistance and taste characteristics.

The thickness of the biaxially stretched polyester film used in the present invention is 5 to 6 in terms of moldability after being laminated on a metal plate, coatability with respect to the metal plate, impact resistance and taste characteristics.
It is preferably 0 μm, more preferably 10 μm.
It is 40 μm.

The center line average roughness Ra of the film is
From the viewpoint of taste characteristics and moldability, 0.001 to 0.
08 μm, more preferably 0.002-0.06 μm
Is. Further, the ratio Rt / Ra with the maximum roughness Rt is 5 to
When it is 50, preferably 8 to 40, high-speed can making property is improved.

When the film is composed of two layers, A layer and B layer, and the A layer is a non-laminated surface and the B layer is a laminated surface, the laminated thickness is 0.01 to 5
From the viewpoint of taste characteristics and moldability, it is preferably 0.1 μm, more preferably 0.1 to 3 μm, and particularly preferably 0.5 μm.
~ 2 μm. The thickness of the B layer is preferably 4 to 60 μm, more preferably 8 to 30 μm.

The particles may be added to either the A layer or the B layer, but the center line average roughness Ra of the B layer is preferably 0.005.
To 0.08 μm, more preferably 0.008 to 0.0
It is 6 μm. Furthermore, the ratio Rt / Ra with the maximum roughness Rt
Is 5 to 50, preferably 8 to 40, whereby the high-speed can making property is improved. The center line average roughness Ra of the layer A is preferably 0.001 to 0.05 μm, more preferably 0.0.
The range of 02 to 0.04 μm is preferable because the taste characteristics are improved.

When the film in the present invention is composed of at least a non-laminated surface layer (A layer) and a laminated surface layer (B layer), the melt specific resistance (ra) of the A layer and the melt specific resistance (b) of the b layer ( It is desirable that the ratio ra / rb of rb) is 2 to 200 in order to improve the thickness unevenness. The method for controlling the melting specific resistance is not particularly limited, but known methods for limiting the amounts of alkali metal compounds, alkaline earth metal compounds, phosphorus compounds and the like can be used in combination.

The amorphous Young's modulus of the film used in the present invention in both the longitudinal direction and the width direction at right angles to the film is 120 to 2
20 kg / mm ² is necessary from the viewpoint of exhibiting excellent moldability, impact resistance, and taste characteristics, preferably 130 to 210 kg / mm ² , and more preferably 140 to 210 kg / mm ² .
200 kg / mm ² , more preferably 150 to 190
It is kg / mm ² . Amorphous Young's modulus is 120 kg / mm ²
If it is less than 1, the impact resistance and the taste characteristics after can making are deteriorated, which is not preferable. On the other hand, if the amorphous Young's modulus exceeds 220 kg / mm ² , the elongation of the film will be low and the formability will be poor.
It is not preferable because sufficient cans cannot be produced. The amorphous Young's modulus is calculated by the following formula and is considered to indicate the easiness of elongation of the amorphous part.

Amorphous Young's modulus is 120 to 220 kg / mm
^The method of ² can be achieved by adopting a high temperature stretching method at the time of film production, but is not particularly limited, and for example, the proper viscosity of the raw material, the catalyst, the amount of diethylene glycol and the stretching conditions, the heat treatment conditions, etc. Can be achieved by

Ea = (1-φ) Ef Here, Ea: amorphous Young's modulus, φ: crystallinity, Ef: Young's modulus of the film. The crystallinity is calculated by the following formula using the density (ρ) measured by a density gradient tube. φ = (ρ-1.335) /0.12

In the present invention, in order to obtain excellent moldability, the elongation at break of the film is preferably 170% or more, more preferably 180% or more, particularly preferably 200% or more in both the longitudinal and transverse directions of the film. . Elongation is 170
If it is less than%, the moldability is deteriorated, which is not preferable.

The method for producing the film (including the laminated film) used in the present invention is not particularly limited, but, for example, after drying each polyester as necessary, the film may be used alone and / or
Alternatively, each is supplied to a known extruder for melt lamination, extruded into a sheet form from a slit die, and brought into close contact with a casting drum by a method such as electrostatic application to be cooled and solidified to obtain an unstretched sheet. A biaxially stretched film is obtained by stretching the unstretched sheet obtained by bringing the sheet into close contact with a casting drum and solidifying by cooling in the longitudinal direction and the width direction of the film.

The draw ratio is the degree of orientation of the desired film,
It can be arbitrarily set according to strength, elastic modulus, etc., but a tenter method is preferable in terms of film quality, and a sequential biaxial stretching method of stretching in the longitudinal direction and then in the width direction, longitudinal direction A simultaneous biaxial stretching method that stretches in the width direction at substantially the same time is desirable.

The draw ratio is 1.5 in each direction.
˜4.0 times, preferably 1.8 to 4.0 times. Either the stretching ratio in the longitudinal direction or the width direction may be increased,
It may be the same. The stretching speed is 1000 to 200.
The stretching temperature is preferably 000% / min, and the stretching temperature can be any temperature as long as it is equal to or higher than the glass transition temperature of polyester, but is preferably 80 to 150 ° C., which exhibits excellent moldability and high elongation. 100 ~ 150 ℃ to get
Is preferred.

Further, the film is subjected to a heat treatment after the biaxial stretching, and this heat treatment can be carried out by any conventionally known method such as in an oven or on a heated roll. The heat treatment temperature can be any temperature between 140 ° C. and 255 ° C., but is preferably 150 to 245 ° C.
The heat treatment time may be arbitrary, but usually 1 to
It is preferably performed for 60 seconds. The heat treatment may be performed while relaxing the film in the longitudinal direction and / or the width direction thereof.

Further, re-stretching may be carried out once or more in each direction, and then heat treatment may be carried out.

Further, the film used in the present invention may be coated with various coatings and is not particularly limited.

The film used in the present invention is 150 ° C. × 30
The heat shrinkage percentage per minute is preferably 7% or less. When the heat shrinkage rate is 7% or less, preferably 6% or less, more preferably 5% or less, particularly preferably 4% or less, not only the thermal laminating property with a metal is excellent but also the impact resistance is improved.

Further, in producing the film used in the present invention, if necessary, additives such as an antioxidant, a plasticizer, an antistatic agent, a weatherproofing agent and a terminal blocking agent can be appropriately used. In particular, the combined use of an antioxidant is preferable because it prevents deterioration of the laminate surface due to heat history during the can making process. The amount is 0.001-1% by weight based on the total film weight.
A degree is preferable.

Next, a method for laminating the film will be described. Considering the production of ordinary laminated metal plates, the film is brought into contact with a heated metal plate, pressure is applied with a roll, the film resin at the interface of the metal plate is melted, and the metal plate is wetted to form a metal plate. We are adhering the film.

When the biaxially stretched polyester film targeted by the present invention is laminated on a metal plate by the above-mentioned method, the film resin is melted at the film-metal plate interface by the heated metal plate. The suppressed molecular mobility expressed by the relaxation time T1ρ, once the film is melted, the suppression effect is canceled, and crystallization is easily caused by heating, and the molding process heat and the heating step after molding are performed. In the high temperature sterilization process after filling the contents, crystals grow on this adhesive interface, resulting in deterioration of adhesion, whitening of film appearance, deterioration of processability, and the like.

As a result of a detailed study by the present inventors, in order to prevent the film from losing the function of suppressing the molecular mobility of the film during lamination, the time of contact with a high-temperature metal plate is strictly limited, and particularly, the metal. It has been found that it is necessary to strictly limit the time the plate is in contact with the film at a temperature above the melting point of the film.

It was also found that when the laminated metal plate is used for a container, the film temperature after lamination and before water cooling has a great influence on the formability and impact resistance. That is, as the film temperature after lamination to water cooling is higher, the molding performance after lamination is more excellent, but when the film exceeds the melting point, the impact resistance is lost, and the crystallization suppressing effect is lost, and heating during the can manufacturing process is performed. Therefore, after this heating step, the moldability and the adhesion of the film are lost. On the other hand, when the film temperature after lamination and before water cooling is low, the impact resistance is excellent, but the film workability of the laminated metal sheet is insufficient, and high-level molding cannot be endured.

The temperature of the film is highest on the surface in contact with the metal plate at the time of lamination. It was found that the processability, impact resistance and retort whitening resistance of the film can be maintained by limiting the temperature of the metal plate during lamination and the lamination time. This is because melting the resin requires temperature and time, so if the temperature is high for a very short time, it does not melt even at a temperature above the melting point and the physical properties of the film are essentially In a state where it remains for a while,
It is considered that since the extreme surface layer portion of the film that is in contact with the metal plate is deformed along the surface of the metal plate, good adhesion is possible.

In the conventional laminating method, since it is difficult to achieve fusion in a short time, it is necessary to laminate at a higher speed.

In order to achieve a high degree of molding and excellent adhesion even after heating in the can making process, the metal plate is heated to a temperature higher than the melting point of the film to start lamination, and the film is pressure-bonded by a roll in the shortest possible time. It was also found that it is indispensable to lower the film temperature to a temperature below the melting point of the film, and it is also important to cool the laminated film at the nip to a temperature below the glass transition point in the shortest possible time.

As a result of further study on such findings,
It has been revealed that the method described below is suitable for laminating the film.

In the present invention, when the above biaxially stretched polyester film is laminated on a metal plate, the temperature T ₀ of the metal plate at the start of lamination is equal to or higher than the melting point T _f of the film, and the nip exit side of the laminating roll. The temperature T ₁ of the metal plate of is less than or equal to the melting point T _f of the film, and the lamination index K defined by the following formula is 1 to 20 ms.
It is necessary to laminate within the range of ec. K = (T ₀ −T _f ) × t / (T ₀ −T ₁ ), where t: nip time

When the lamination index K is less than 1 msec, the film is not sufficient to adhere to the metal plate,
Peel during processing without enduring processing. 20 msec
If it exceeds, the effect of suppressing molecular mobility near the contact surface with the metal plate is lost. Molding performance can be obtained as it is, but when subjected to heating such as strain relief of the film after molding, near the interface between the film and the metal plate of the laminated metal plate,
Spherulites grow, resulting in adhesion, molding performance after heating, whitening in the sterilization step after filling the contents, and the like. The more preferable range of the lamination index K is 2 to 15 ms.
ec, a particularly preferred range is 5 to 10 msec.

In order to obtain good adhesion, retort whitening resistance, and workability, the metal plate temperature T ₀ at the start of lamination is equal to or higher than the melting point T _f of the film, and the temperature T ₁ of the metal plate on the nip exit side of the laminating roll. _{Is set to be} equal to or lower than the melting point T _f of the film.

When the temperature T ₀ of the metal plate at the start of lamination exceeds the film melting point + 40 ° C., the film is easily melted at the interface of the laminate. There is a case where the adhesion is insufficient and it becomes difficult to secure the adhesion after processing. Therefore, the temperature T ₀ of the metal plate at the start of lamination is the film melting point + 2 ° C to the film melting point +4.
It is preferably in the range of 0 ° C., more preferably in the range of film melting point + 10 ° C. to film melting point + 40 ° C.,
A particularly preferred range is from the film melting point + 20 ° C to the film melting point + 30 ° C.

If the nip time (nip length / laminating speed) exceeds 0.05 sec, the laminating time becomes too long, and either the workability or the impact resistance is deteriorated. If it is less than 0.005 sec, the adhesion between the metal plate and the film becomes insufficient, and it may be difficult to secure the adhesion after processing. Therefore, the preferable nip time is 0.005 to 0.05 sec, more preferably 0.01 to 0.04 sec, and particularly preferably,
It is 0.015 to 0.03 sec.

The nip pressure is the roll pressure divided by the nip area, and the nip pressure is 1 to 30 kg.
/ Cm ² is preferred. If it is too low, even if it is above the melting point, the time is short and the deformation during adhesion is not sufficient, and it is difficult to obtain sufficient adhesion. Furthermore, the cooling effect during bonding cannot be sufficiently obtained. Even if the applied pressure is large, there is no particular disadvantage in terms of quality, but the force applied to the laminating roll is large, and the strength of the equipment is required, so the equipment becomes large and uneconomical. More preferable range of pressing force is 5 to 20 k
g / cm ² , and a particularly preferred range is 5 to 15 kg / cm ² .

If the ratio of the diameter of the laminating roll / the laminating speed exceeds 0.3 sec, it becomes difficult to control the plate temperature on the inlet side and the outlet side of the laminating roll within the desired range while laminating in a short time. Therefore, the ratio of laminating roll diameter / laminating speed is 0.3 sec.
The following is preferable, and 0.25se is more preferable.
c or less, particularly preferably 0.2 sec or less.

If the time after laminating until water cooling exceeds 5 seconds, crystallization will proceed and workability and adhesion after processing will deteriorate, so less than 5 seconds is preferable. More preferably 2
It is less than sec, particularly preferably less than 1 sec. There is no particular inconvenience even if the laminating time is short. The water temperature during water cooling is not particularly specified, but is preferably a temperature not higher than the glass transition point of the film. In the case of a film having two or more layers, it is preferable that the glass transition temperature is lower than the lower temperature.

If necessary, after laminating, a paraffin wax or the like may be applied to the surface to impart lubrication performance when processing the can.

The metal plate of the present invention is not particularly limited,
A metal plate made of iron, aluminum or the like is preferable in terms of formability. Furthermore, in the case of a metal plate made of iron, an inorganic oxide coating layer that improves the adhesion and corrosion resistance on the surface of the metal plate, for example, chromic acid treatment, phosphoric acid treatment, chromic acid / phosphoric acid treatment, electrolytic chromic acid treatment A chemical conversion treatment coating layer represented by, for example, chromate treatment or chromium chromate treatment may be provided. Particularly, in terms of metallic chromium, 6.5 to 6.5 as chromium
Preferably the metal plate having the upper layer of metallic chromium and 150 mg / m ² of chromium layer and 5 to 30 mg / m ² of hydrated oxide,
In addition, malleable metal plating layers such as nickel, tin,
Zinc, aluminum, gun metal, brass, etc. may be provided. For tin plating 0.5-15 / m ^2, it is preferable to have a plating amount when nickel or aluminum 1.8~20g / m ^2.

The laminated metal sheet of the present invention can be suitably used for coating the inner surface of a two-piece metal can produced by drawing or ironing. Further, it can be preferably used for coating the lid portion of a two-piece can or the body, lid, and bottom of a three-piece can because it has good metal adhesion and moldability.

[0067]

The present invention will be described in detail below with reference to examples.

As a metal plate, a continuously cast slab of low carbon Al-killed steel was hot-rolled, descaled, cold-rolled, annealed, temper-rolled, temper T4CA, dimension 0.19.
Using a cold-rolled steel strip of 6 mm x 920 mm, degreasing, pickling, and electrolytic chromate treatment followed by metal chromium 130
A TFS plated with mg / m ² and chromium oxide of 15 mg / m ² was prepared.

As the biaxially stretched polyester film, a PET film consisting of one layer or two layers having a thickness of 25 μm was prepared.

The prepared biaxially stretched polyester film was laminated on the prepared metal plate. At the time of lamination, following the heating with a steel roll, the plate temperature of TFS at the time of lamination was heated to 282 ° C. using an induction heating roll, and the film was laminated on both sides by applying pressure with a laminating roll having a width of 1400 mm. Water temperature after lamination 7
After cooling in distilled water at 5 ° C, paraffin wax was applied to both sides using a roll coater at 50 mg / m ² per side.
It was applied and wound up to produce a laminated metal plate. In the case of a two-layer film, the layer B was laminated so that the layer B was the laminating surface. The performance of the laminated metal plate obtained above was investigated.

Table 1 shows the investigation results of the properties, laminating conditions and performance of the prepared biaxially stretched polyester film. The abbreviations in Table 1 are as follows. PET: Polyethylene terephthalate PET / I: Isophthalic acid copolymerized polyethylene terephthalate (numerical values are copolymerized mol%) DEG: Diethylene glycol

The characteristics of the film are as follows (1)-
(6) The characteristics of the laminated metal plate are as follows (7) to (1)
It was measured and evaluated by the method of 1). Furthermore, (7) to (1
A comprehensive evaluation is performed on the evaluation result of 1), and (7)-
If the evaluation of (11) is good or better, the overall evaluation is: ○,
If any of the evaluations is below, the overall evaluation:
It was set to x.

(1) Content of diethylene glycol component in polyester It was measured by NMR ( ¹³ C-NMR spectrum).

(2) Content of Metal Element in Polyester The content of the element in the polyester composition and the peak intensity were quantified by fluorescent X-ray measurement.

(3) Intrinsic viscosity of polyester Dissolve polyester in orthochlorophenol and prepare 25
It was measured at ° C.

(4) Melting point of polyester Crystallization of polyester was performed at 10 ° C./min with a differential scanning calorimeter (DSC-2 type manufactured by Perkin Elmer Co., Ltd.).
The heating rate was measured.

(5) Content of acetaldehyde in the film 2 g of the fine powder of the film was sampled and charged into a pressure vessel together with ion-exchanged water, extracted with water at 120 ° C. for 60 minutes, and then quantified by high sensitivity gas chromatography.

(6) Young's Modulus, Elongation, Amorphous Young's Modulus Tensile Young's modulus, ASTM-D882-81 (A
Method). The breaking elongation at that time was defined as the elongation. The amorphous Young's modulus was calculated from the above Young's modulus (Ef) by the following formula. Amorphous Young's modulus (Ea) = (1-φ) Ef

Φ is the crystallinity and is calculated by the following formula from the density (ρ) measured using a density gradient tube. φ = (ρ-1.335) /0.12

(7) Formability sample was drawn using a drawing machine.
A can was obtained in the three stages of drawing ratio (diameter before molding / diameter after molding) 1.6, 2.1, and 2.8 in a temperature range that can be molded at 80 to 100 ° C. Put 1% saline solution into the cans obtained in the second and third molding steps, apply a voltage of 6v to the electrode in the saline solution and the metal can, read the current value after 3 seconds, and measure 10 cans. The subsequent average value was obtained and the following evaluations were made. Excellent: Less than 0.001 mA Good: 0.001 mA or more and less than 0.01 mA Possible: 0.01 mA or more and less than 0.1 mA Impossible: 0.1 mA or more

(8) Impact resistance After the third stage draw forming process, water was fully poured into cans having good formability evaluations, and 10 pieces for each test from the height of 1 m to the PVC tile floor surface. Then, apply a voltage of 6v to the electrode and the metal can and read the current value after 3 seconds.
The average value after measuring 10 cans was calculated and evaluated as follows. Excellent: Less than 0.001 mA Good: 0.001 mA or more and less than 0.01 mA Possible: 0.01 mA or more and less than 0.1 mA Impossible: 0.1 mA or more

(9) Retort whitening resistance After canning after the third stage draw forming, the can was fully filled with water, and then the lid was tightened.
It was kept in pressurized steam at 30 ° C. for 30 minutes, and the degree of whitening of the bottom surface and the body portion was visually judged according to the following criteria. Yu: No change. Good: Almost no change was observed. Acceptable: A slight whitening is partially observed. No: Whitening is observed on the whole.

(10) Adhesion after heat processing The can after the third stage draw forming was heated at 200 ° C for 2 hours.
After heating for one minute to remove the wax content, the upper part of the can was subjected to neck-in drawing processing, and subsequently, flange molding was performed for lid winding. The degree of adhesion of the film on the inner and outer surfaces of the flange portion was judged according to the following criteria. Yu: No change. Good: Almost no change was observed. Acceptable: A slight peeling is observed at the end. No: Peeling is observed on the entire flange.

(11) Taste characteristics After the third step of draw forming, the can was subjected to pressure steam treatment at 120 ° C. for 30 minutes, and then the perfume aqueous solution d-limonene 25p.
350 ml of a pm aqueous solution was filled, the mixture was sealed at 40 ° C., left for 45 days, and then opened, and a sensory test was performed to evaluate changes in odor according to the following criteria. Yu: No change in odor was observed. Good: Almost no change in odor. Fair: Slight change in odor can be seen. No: A large change is seen in the odor.

[0085]

[Table 1]

Inventive Examples 1 to 9 satisfying the scope of the present invention all have good moldability, and also have good impact resistance to adhesiveness after heat processing, and the overall evaluation is good.

Comparative Examples 1 and 2 in which the amorphous Young's modulus is out of the range of the present invention are inferior in moldability and are inferior in any of taste characteristics, retort whitening resistance, and adhesion after heating. In Comparative Examples 3 to 6 in which the laminating index is out of the range of the present invention, the moldability is inferior to that of the present invention, and the retort whitening resistance and the adhesion after heating are obviously inferior to those of the present invention. In each of Comparative Examples 1 to 6, the comprehensive evaluation is x.

[0088]

EFFECTS OF THE INVENTION The biaxially stretched polyester film-laminated metal sheet of the present invention is not only excellent in moldability when molded into a can, but also excellent in taste characteristics, impact resistance, retort whitening resistance and the like. And is suitable as a material for a lid or a body of a metal can manufactured by molding.

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masahiko Shigeno 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Japan Steel Pipe Co., Ltd. (72) Inventor Shinsuke Watanabe 1-2-1 Marunouchi, Chiyoda-ku, Tokyo Nippon Steel Pipe Within the corporation (56) Reference JP 4-201237 (JP, A) JP 9-1555969 (JP, A) JP 5-98465 (JP, A) JP 6-340047 (JP, A) (58) Fields surveyed (Int.Cl. ⁷ , DB name) B29C 63/00-65/82 B32B 1/00-35/00 B29C 55/12 C08J 5/18

Claims (7)

(57) [Claims] 1. An amorphous Young's modulus is 120 to 220 kg / m.
When laminating the biaxially stretched polyester film of m ^{2 on} at least one side of the metal plate, the temperature T ₀ of the metal plate at the start of lamination is equal to or higher than the melting point T _f of the film and the temperature T of the metal plate on the exit side of the laminating roll nip. _{1. A} method for producing a laminated metal sheet, which comprises laminating ₁ to a melting point T _f of the film or less and further setting a laminating index K defined by the following equation within a range of 1 to 20 msec. K = (T ₀ −T _f ) × t / (T ₀ −T ₁ ), where t: nip time 2. The amorphous Young's modulus is 140 to 200 kg / m.
When laminating a biaxially stretched polyester film of m ² on a metal plate, the temperature T of the metal plate at the start of lamination
₀ The film melting point T _f or more, the temperature T ₁ of the metal plate of the lamination roll nip exit side as well as below the melting point T _f of the film, and a laminate index K which is defined further by the following formula in the range of 1~20msec A method of manufacturing a laminated metal plate, which comprises laminating the metal plates. K = (T ₀ −T _f ) × t / (T ₀ −T ₁ ), where t: nip time 3. When laminating a biaxially stretched polyester film in which 95 mol% or more of the polyester units constituting the film are ethylene terephthalate units to a metal plate, the temperature T ₀ of the metal plate at the start of lamination is set to the melting point of the film. The temperature T ₁ of the metal plate on the exit side of the laminating roll nip is set to T _f or more and the melting point of the film is set to T _f or less, and the laminating index K defined by the following formula is 1 to 2
A method for producing a laminated metal plate, which comprises laminating within a range of 0 msec. K = (T ₀ −T _f ) × t / (T ₀ −T ₁ ), where t: nip time 4. 95 mol% or more of the polyester units constituting the film are ethylene terephthalate units,
When a biaxially stretched polyester film having an amorphous Young's modulus of 120 to 220 kg / mm ² is laminated on a metal plate, the temperature T ₀ of the metal plate at the start of lamination is equal to or higher than the melting point T _f of the film and the laminating roll nip exit side. The temperature T ₁ of the metal plate is set to be equal to or lower than the melting point T _f of the film, and the lamination index K defined by the following formula is set to 1 to 20.
A method for producing a laminated metal plate, comprising laminating within a range of msec. K = (T ₀ −T _f ) × t / (T ₀ −T ₁ ), where t: nip time 5. The ethylene terephthalate unit accounts for 95 mol% or more of the polyester unit constituting the film,
When a biaxially stretched polyester film having an amorphous Young's modulus of 140 to 200 kg / mm ² is laminated on a metal plate, the temperature T ₀ of the metal plate at the start of lamination is equal to or higher than the melting point T _f of the film, and the laminating roll nip exit side. The temperature T ₁ of the metal plate is set to be equal to or lower than the melting point T _f of the film, and the lamination index K defined by the following formula is set to 1 to 20.
A method for producing a laminated metal plate, comprising laminating within a range of msec. K = (T ₀ −T _f ) × t / (T ₀ −T ₁ ), where t: nip time 6. The nip time t is 0.005 to 0.05 s.
It is in the range of ec, The manufacturing method of the laminated metal plate in any one of Claims 1-5 characterized by the above-mentioned. 7. The film is composed of at least two layers and the intrinsic viscosity difference between the non-laminated surface and the laminated surface is 0.01 to 0.5.
The method for manufacturing a laminated metal plate according to claim 6.