JP2020019166A - Polyester resin-coated metal plate, method for manufacturing polyester resin-coated metal plate, and container and container lid formed of the polyester resin-coated metal plate - Google Patents

Abstract

To provide a polyester resin-coated metal plate which can suppress generation of retort brushing (white spot) and is excellent in impact resistance, moldability, retort adhesion, and the like, in a container and a container lid such as a beverage can and a food product can.SOLUTION: A polyester resin-coated metal plate has a metal plate 1 and a polybutylene terephthalate layer A stacked so as to contact at least one surface of the metal plate 1, in which an X-ray diffraction intensity ratio R of an X-ray diffraction intensity of plane (100) to an X-ray diffraction intensity ratio of plane (1-11) in the polybutylene terephthalate layer A is within the range of 1.3 or more and 6.6 or less. The X-ray diffraction intensity of the plane (100) is the maximum value seen at a diffraction angle 2θ of 23.0° to 24.0°, the X-ray diffraction intensity of the plane (1-11) is the maximum value seen at a diffraction angle 2θ of 25.0° to 26.0°, and the X-ray diffraction intensity ratio R is a ratio of diffraction intensity of plane (100) to diffraction intensity of plane (1-11).SELECTED DRAWING: Figure 1

Description

  The present invention relates to a polyester resin-coated metal plate, a method for producing a polyester resin-coated metal plate, a container made of the polyester resin-coated metal plate, and a container lid.

  BACKGROUND ART Conventionally, a resin-coated metal plate in which a thermoplastic resin film is laminated on a metal plate surface is known as a material for containers such as metal cans for beverages and foods. As the thermoplastic resin film, a polyester film or the like is used.

  Containers such as metal cans for beverages and foods as described above need to be able to withstand retort sterilization performed after filling the contents. The retort sterilization treatment includes a plurality of methods such as a batch type and a continuous type.For example, the batch type retort treatment includes a step of exposing a container such as a metal can to high-temperature steam for several minutes to several tens of minutes. . In addition, the continuous retort treatment includes a step of exposing a container such as a metal can conveyed to a sterilization chamber by an endless chain conveyor into high-temperature steam for several minutes to several tens of minutes. In recent years, continuous production lines, which are relatively new systems compared to the batch system, have been increasing for the purpose of improving productivity.

  In this new type of continuous production line, heating and heating are extremely fast, such as dipping the filled containers into high-temperature hot water while transporting them, so that the containers are stacked on the surface of the metal plate more than previously assumed. This is a severe environment for the thermoplastic resin film. Heat for laminating metal sheets, which has the property that delamination of films from metal sheets does not occur even under severe retort sterilization treatment environments with extremely high temperature rising rates such as continuous production lines. There is a strong need for a plastic resin film.

  In addition, during the retort sterilization treatment as described above, the problem of retort brushing (white spots) that may occur on the top lid of a three-piece can or the bottom of a two-piece can on the outer surface side of a container such as a metal can has been studied. Have been. The retort brushing (white spots) is a phenomenon in which the resin layer that has undergone the above-described retort sterilization treatment becomes partially white and impairs the appearance.

  There are several possible causes of the occurrence of such retort brushing (white spots). During the retort sterilization treatment, a portion where water droplets adhere to the can lid or the bottom of the can and a portion where water droplets do not adhere are formed. It is estimated that the film crystallizes faster and therefore looks whiter than other parts.

Alternatively, it is also presumed that water droplets adhering to the can lid or the bottom of the can pass through the thermoplastic resin film and become bubbles between the metal plate and the resin film. In addition, during the retort sterilization treatment, it is presumed that the water contained in the film foams inside the film when it reaches the vaporization temperature due to a sudden rise in temperature, so that the portion looks white.
In any case, there is a great dependence on the heating rate of the retort pot, and there is a need for the development of a thermoplastic resin-coated metal container that can be applied to a retort pot with a particularly high heating rate, such as a continuous production line.

  In order to improve such a problem of retort brushing (white spots), a method of using a resin in which polyethylene terephthalate (PET) is blended with polybutylene terephthalate (PBT) has been proposed as a thermoplastic resin film. Since PBT has a high crystallization rate, the film is crystallized in a short time from the start of the retort sterilization treatment, thereby suppressing water vapor transmission and suppressing the occurrence of retort brushing (white spots). It cannot be applied to applications in which the temperature of the retort kettle is extremely high, as in the production line of the formula.

  On the other hand, a homopolymer of polybutylene terephthalate (PBT) having a higher crystallization rate has been considered to be effective as a method for further improving the resistance to retort brushing (white spots) due to the higher crystallization rate. .

  For example, Patent Literature 1 discloses a resin-coated steel sheet for a container in which an unoriented polybutylene terephthalate (PBT) homopolymer is coated on a steel sheet.

  Patent Document 2 discloses a laminated metal plate in which a biaxially stretched polybutylene terephthalate film is laminated, for example, as a laminated metal plate for a can used as a material for a beverage can or a food can, in contact with the surface of the metal plate. I have.

JP 2001-1447 A Japanese Patent No. 4765257

  The technique disclosed in Patent Document 1 aims at improving thermal embrittlement and thermal shrinkage of a film in a coating baking process and a welding process by setting a specific polyester film in an unoriented state. The use of the container is not premised on the retort sterilization treatment, and its performance is not confirmed on the assumption that retort adhesion is required.

  On the other hand, a stretched polybutylene terephthalate film as disclosed in Patent Document 2 has a merit that the film strength is large by stretching and the dimensional stability is good, so that the wound shape of the film is not easily collapsed. That is, it is preferable to use a stretched film from the viewpoint of productivity, since the risk of film breakage or film wrinkling when laminating on a metal plate is reduced. However, since the stretched polybutylene terephthalate film has higher crystallinity than the stretched polyethylene terephthalate film and has a large residual stress inside the film due to the oriented crystal by stretching, when the resin-coated metal plate is processed into a container or a lid, There was a problem that the film was easily peeled off during the retort sterilization treatment.

  In view of the various problems as described above, the present inventors have solved the problem of retort brushing (white spots) under retort conditions with a very high heating rate, such as a continuous retort method, and at the same time, have improved the impact resistance and the container. In order to solve the moldability of the film and the container lid, and the adhesiveness of the film during the retort sterilization treatment (retort adhesiveness), intensive studies were made.

  As a result, the inventors have found that the above-mentioned problems can be solved simultaneously by controlling the oriented crystals of the film to a specific state in a polyester resin-coated metal plate on which a polybutylene terephthalate film is laminated, and have reached the present invention.

The present invention has the following features.
(1) A polyester resin-coated metal plate of the present invention has a metal plate and a polybutylene terephthalate layer laminated so as to be in contact with at least one surface of the metal plate, and the (100) plane in the polybutylene terephthalate layer Wherein the ratio R of the X-ray diffraction intensity of the (1) to the X-ray diffraction intensity of the (1-11) plane is in the range of 1.3 or more and 6.6 or less. (However, the X-ray diffraction intensity of the (100) plane is the maximum value at which the diffraction angle 2θ is found in the range of 23.0 ° to 24.0 °, and the X-ray diffraction intensity of the (1-11) plane is Is the maximum value at which the diffraction angle 2θ is found in the range of 25.0 ° to 26.0 °, and the X-ray diffraction intensity ratio R = (100) plane diffraction intensity / (1-11) plane diffraction intensity Is.)
(2) In the polyester resin-coated metal plate according to the above (1), the polybutylene terephthalate layer is laminated on one surface of the metal plate, and the polybutylene terephthalate layer is formed on the other surface of the metal plate. Preferably, different polyester resin layers are laminated.
(3) In the polyester resin-coated metal sheet according to (2), the different polyester resin layer is a polyethylene terephthalate resin layer, a polyethylene terephthalate resin layer in which isophthalic acid is copolymerized, or a blend of polyethylene terephthalate and polybutylene terephthalate. Or a resin layer in which polyethylene terephthalate copolymerized with isophthalic acid and polybutylene terephthalate are blended.
(4) In the polyester resin-coated metal plate according to the above (2) or (3), the different polyester resin layers are preferably laminated in an unoriented state.
(5) In the polyester resin-coated metal sheet according to any one of the above (1) to (4), it is preferable that the X-ray diffraction intensity ratio R is in a range of 1.3 or more and 3.0 or less.
(6) In the polyester resin-coated metal sheet according to the above (5), it is more preferable that the X-ray diffraction intensity ratio R is in a range of 1.3 or more and 2.7 or less.
(7) A container of the present invention is formed by using the polyester resin-coated metal plate according to any one of the above (1) to (6).
(8) A container lid of the present invention is formed by using the polyester resin-coated metal plate according to any one of the above (1) to (6).
(9) In the method for producing a polyester resin-coated metal plate of the present invention, the X-ray diffraction intensity of the (100) plane and the X-ray diffraction of the (1-11) plane of the polybutylene terephthalate layer after lamination are provided on at least one surface of the metal plate. A method for producing a polyester resin-coated metal plate, comprising laminating a biaxially stretched polybutylene terephthalate film using a laminating roll so that a line diffraction intensity ratio R falls within a range of 1.3 or more and 6.6 or less. The plate temperature of the plate is in the range of 240 ° C. to 300 ° C., and the surface temperature of the laminating roll is in the range of 30 ° C. to 180 ° C., and the plate temperature of the metal plate before lamination and the surface temperature of the laminating roll. A laminating step of laminating the biaxially stretched polybutylene terephthalate film on the metal plate under the condition that the temperature difference of 80 ° C. or more is secured, and after the laminating step, An orientation return step in which the oriented crystals of the biaxially oriented polybutylene terephthalate film dissolved in the laminating step are restored, and after the orientation return step, the metal plate on which the biaxially oriented polybutylene terephthalate film is laminated is quenched. And a quenching step. (However, the X-ray diffraction intensity of the (100) plane is the maximum value at which the diffraction angle 2θ is found in the range of 23.0 ° to 24.0 °, and the X-ray diffraction intensity of the (1-11) plane is Is the maximum value at which the diffraction angle 2θ is found in the range of 25.0 ° to 26.0 °, and the X-ray diffraction intensity ratio R = (100) plane diffraction intensity / (1-11) plane diffraction intensity Is.)

ADVANTAGE OF THE INVENTION According to this invention, while resolving the problem of retort brushing (white spots) at the time of retort sterilization processing (retort brushing resistance), impact resistance after performing severe processing, such as drawing and ironing, and can production. It is possible to provide a polyester resin-coated metal plate excellent in moldability that can withstand severe processing such as drawing and ironing, and adhesion between the film and the metal plate during retort sterilization (retort adhesion).
Further, according to the present invention, it is possible to provide a method for producing a polyester resin-coated metal plate, a container made of the polyester resin-coated metal plate, and a container lid.

It is sectional drawing which shows typically the example of the polyester resin coating metal plate of this embodiment. It is sectional drawing which shows another example of the polyester resin coating metal plate of this embodiment typically. It is a schematic diagram which shows the example of the manufacturing apparatus of the polyester resin coating metal plate of this embodiment. FIG. 3 is a view showing an X-ray diffraction peak intensity of a polybutylene terephthalate layer A of a polyester resin-coated metal plate in Example 1. FIG. 9 is a view showing an X-ray diffraction peak intensity of a polybutylene terephthalate layer A of a polyester resin-coated metal plate in Example 2.

  Hereinafter, the present invention will be described in detail with the following embodiments. Note that the present invention is not limited to the following embodiments.

[Polyester resin coated metal plate]
As shown in FIG. 1, the polyester resin-coated metal plate in the present embodiment includes a metal plate 1 and a polybutylene terephthalate layer A laminated (laminated) so as to be in contact with at least one surface of the metal plate 1.
The polybutylene terephthalate layer A is preferably provided on the outer side when the metal plate 1 is formed into a container or a container lid.

<Metal plate 1>
As the metal plate 1, a known metal plate used for a container such as a normal metal can or a container lid can be used, and is not particularly limited. For example, as a metal plate that is preferably used, a surface-treated steel plate or a light metal plate such as an aluminum plate and an aluminum alloy plate can be used.

  Aluminum-killed steel, low-carbon steel, or the like can be used as the surface-treated steel sheet. For example, after cold-rolled steel sheet is subjected to secondary cold rolling, tin plating, nickel plating, zinc plating, electrolytic chromic acid treatment, chromic acid treatment, non-chromium treatment using aluminum or zirconium, one or more types Can be used.

As the light metal plate, an aluminum plate and an aluminum alloy plate are used. As the aluminum alloy plate, for metal cans, for example, JIS A3000 (Al-Mn) can be used. For the can lid, for example, JIS A5000-based (Al-Mg-based) can be used.
The thickness and the like of the metal plate can be appropriately selected according to the purpose of use.

<Polybutylene terephthalate layer A>
In this embodiment, a polybutylene terephthalate layer A is provided on at least one surface of the metal plate 1. The polybutylene terephthalate layer A is characterized by being composed of a homopolymer of polybutylene terephthalate (PBT). That is, the polybutylene terephthalate layer A of the present embodiment is not a blend film with polyethylene terephthalate (PET) or the like, and does not include a copolymer component such as isophthalate.

The homopolymer of polybutylene terephthalate (PBT) in the present embodiment preferably has a melting point (Tm) of 215 ° C. to 225 ° C. and an intrinsic viscosity (IV value) of 1.15 to 1.30 dl / g. . In addition, additives such as a lubricant, an antiblocking agent, an inorganic extender, an antioxidant, an ultraviolet absorber, an antistatic agent, a flame retardant, a plasticizer, a colorant, a crystallization inhibitor, and a crystallization accelerator, as necessary. May be added.
Further, as a method for producing a polybutylene terephthalate film, it is difficult to apply a sequential biaxial stretching method due to a high crystallization rate, and production by a simultaneous biaxial stretching method is general. Examples of the simultaneous biaxial stretching method include a tubular method and a tenter method, but the tubular method is particularly preferable in that the strength balance in the vertical and horizontal directions is good. The stretching ratio is preferably in the range of 2.7 to 4.5 times for each of MD and TD in consideration of the strength physical properties, transparency, and thickness uniformity of the film.

<X-ray diffraction intensity ratio>
In the polybutylene terephthalate layer A in the present embodiment, the ratio R of the X-ray diffraction intensity of the (100) plane to the X-ray diffraction intensity of the (1-11) plane is in the range of 1.3 or more and 6.6 or less. Features. Here, the X-ray diffraction intensity of the (100) plane is the maximum value at which the diffraction angle 2θ is confirmed in the range of 23.0 ° to 24.0 °, and the X-ray diffraction intensity of the (1-11) plane is Is the maximum value observed when the diffraction angle 2θ is in the range of 25.0 ° to 26.0 °. The X-ray diffraction intensity ratio R represents the value of “(100) plane diffraction intensity / (1-11) plane diffraction intensity”.
In this specification, for convenience of notation,
Is described as “(1-11) plane”.

  Generally, it is known that the peak at which the diffraction angle 2θ is found in the range of 23.0 ° to 24.0 ° in X-ray diffraction is the intensity brought about by the oriented crystal of PBT. This is because the benzene ring in the molecular chain of PBT is plane-oriented to the (100) plane.

On the other hand, the peak where the diffraction angle 2θ is confirmed in the range of 25.0 ° to 26.0 ° is the diffraction intensity of the (1-11) plane. The (1-11) plane is a plane inclined at 45 ° with respect to the (100) plane of the film surface.
Therefore, the observation of the peak derived from the (1-11) plane is considered to mean that a part of the benzene ring in the PBT is oriented at 45 ° to the film surface. .

  The peak derived from the (1-11) plane is observed in any of a homopolymer of polyethylene terephthalate (PET), a copolymer film of polyethylene terephthalate and isophthalate (PET / I), and a blend film of PET and PBT. It is not strongly observed. Therefore, the peak derived from the (1-11) plane is presumed to be a peculiar phenomenon in the PBT homopolymer.

In the present embodiment, the meaning of defining the X-ray diffraction intensity ratio R of the (100) plane and the X-ray diffraction intensity of the (1-11) plane is as follows.
As described above, it is known that the X-ray diffraction intensity of PBT appears strongly when the orientation of the benzene ring in the molecular chain is aligned with a specific plane.

  In the oriented crystal obtained by stretching, the X-ray diffraction intensity appears on the (100) plane because the benzene rings are aligned parallel to the film surface.

  On the other hand, when the stretched film is brought into contact with a heated metal plate for lamination, for example, the stretched film is melted by heat during lamination, so that the oriented crystals by stretching are broken. Thereafter, during the period from immediately after lamination until the laminate plate is rapidly cooled, a phenomenon occurs in which the collapsed oriented crystal tends to return to the original orientation state (hereinafter, in the present invention, focusing on this phenomenon, it is also referred to as “orientation return”). Name). It is considered that this orientation return is caused by the crystallization speed of PBT as described above.

  It has been found that a new X-ray diffraction intensity appears on the (1-11) plane due to this orientation return. The peak of the X-ray diffraction intensity in the (1-11) plane is not observed in the biaxially stretched film of the PBT homopolymer, but in the laminated metal plate obtained by thermocompression-bonding the biaxially stretched film under specific laminating conditions. Observation has been confirmed in the present invention.

  Therefore, the present inventors, in the polybutylene terephthalate layer A of the polyester resin-coated metal plate, by strictly controlling the amount of the oriented crystal and the amount of the orientation return, impact resistance, moldability, retort adhesion, It has been found that favorable results are obtained in all cases. Then, as a method for strictly controlling the amount of the oriented crystal and the amount of the orientation return, the ratio R of the X-ray diffraction intensity of the (100) plane to the X-ray diffraction intensity of the (1-11) plane is 1.3 or more. That is, the range of 6 or less was reached.

In the above description, an example is described in which the value of the X-ray diffraction intensity ratio R is set in a preferable range by a method of thermally bonding a biaxially stretched PBT film to a metal plate, but the present embodiment is limited to this example. is not.
That is, if the X-ray diffraction intensity ratio R of the laminated PBT film is within the specified range by a method other than the thermal bonding, the impact resistance, moldability, retort adhesion, retort brushing resistance required by the present invention are required. , It is possible to obtain preferable characteristics.

When the oriented crystal of the biaxially stretched PBT film is broken by the heat generated during lamination, the peak of the X-ray diffraction intensity of the (100) plane after laminating is the X-ray diffraction of the (100) plane of the raw film before lamination. It was confirmed that a peak of the X-ray diffraction intensity of the (1-11) plane appeared within a range of 60% or less of the intensity peak. This is because in the region where the X-ray diffraction intensity on the (100) plane is 60% or less, the so-called “melt layer” in which the oriented crystals are completely dissolved on the contact side between the metal plate and the biaxially stretched PBT film during lamination. It is presumed that an oriented layer is formed. It is known that the thicker the “melt layer” is, the more it contributes to the improvement of adhesion. However, in the case of a resin having a high crystallization rate such as PBT, the extremely short time until the “melt layer” is rapidly cooled is obtained. It is assumed that the peak of the X-ray diffraction intensity appears on the (1-11) plane because the orientation is restored in time.
Therefore, it can be said that the peak of the X-ray diffraction intensity on the (1-11) plane is a parameter linked to the change in the peak of the X-ray diffraction intensity on the (100) plane, which is an index of the oriented crystal. When the oriented crystal is further broken down by heat, the peak of the X-ray diffraction intensity of the (1-11) plane gradually decreases, while the X-ray diffraction intensity of the (100) plane, which is an index of the oriented crystal, is larger. Shows a downward trend. In the present invention, it has been found that when the difference between the two peak intensities linked with each other is small and the intensity ratio is within the above-specified range, both the moldability and the retort adhesion can be achieved.
Specifically, it was confirmed that the ratio between the X-ray diffraction intensity of the (100) plane and the X-ray diffraction intensity of the (1-11) plane had to be 6.6 or less.

  That is, when a large amount of oriented crystals exist in the polybutylene terephthalate layer A, the elongation of the polybutylene terephthalate layer A decreases, which causes a reduction in the moldability of the polyester resin-coated metal sheet. Further, since the heat shrinkage stress of the polybutylene terephthalate layer A is large at the time of the retort sterilization treatment, there is a problem that the polybutylene terephthalate layer A is easily separated from the metal plate 1 (insufficient retort adhesion).

As described above, in the stretched PBT film, the X-ray diffraction intensity is observed not only on the (100) plane but also on the (1-11) plane. The X-ray diffraction intensity of the (1-11) plane was such that the oriented crystals in the film were completely melted by heat during lamination, that is, the so-called “melt layer” was formed on the contact side between the metal plate and the film. Can be considered. Therefore, a state where a certain amount of X-ray diffraction intensity peaks can be confirmed on the (1-11) plane is considered to represent a state where a certain amount of a “melt layer” that effectively acts on the adhesion is formed. .
On the other hand, since PBT is a resin with a very high crystallization rate, if the cooling is not performed in a short time after lamination, the above-mentioned orientation return increases the ratio of returning to the original oriented crystal state, resulting in sufficient adhesion. May not be able to be secured. From these estimations, the peak of the X-ray diffraction intensity on the (1-11) plane indicates that a certain amount of the “melt layer” effectively acting on the adhesion is formed, and that the amount of orientation return after lamination is small. We thought that it could be an index to show that it was suppressed.

By controlling the oriented crystals in the film using a parameter based on the peak intensity in the (1-11) plane, the present inventors achieved the required formability and retort adhesion even in the PBT single film. I thought I could.
Furthermore, it was considered that both the properties of the moldability and the retort adhesiveness could be compatible with more preferable dimensions by the ratio of the peak intensities in both the (100) plane and the (1-11) plane.

Since it is not realistic that the X-ray diffraction intensity of the (1-11) plane is larger than the X-ray diffraction intensity of the (100) plane, it is not realistic that the X-ray diffraction intensity ratio R is less than 1.3. It is not a target.
On the other hand, when the above-mentioned X-ray diffraction intensity ratio R exceeds 6.6, the amount of the oriented crystal of the (100) plane is too large relative to the amount of the orientation return of the (1-11) plane. When performing severe processing such as drawing or drawing and ironing, or during retort sterilization, the film may peel off from the metal plate, which is not preferable.

  The ratio R of the X-ray diffraction intensity of the (100) plane and the X-ray diffraction intensity of the (1-11) plane is more preferably 1.3 or more and 3.0 or less, and 1.3 or more and 2.7 or less. Is more preferable.

In the present embodiment, the measurement of the peak intensity in the X-ray diffraction of the polybutylene terephthalate layer A can be performed by a general resin X-ray diffraction measurement method.
For example, the resin-coated surface of the metal plate on which the polybutylene terephthalate layer A is formed is measured using an X-ray diffractometer. As an example of the measurement conditions, Cu (wavelength λ = 0.1542 nm) is used as an X-ray tube (target), and a light receiving slit is selected so that a diffraction peak can be separated at a tube voltage of 40 kV and a tube current of about 200 mA. .

The sample is mounted so that the incident angle and the reflection angle of the X-ray are each θ with respect to the diffraction angle 2θ, and the incident X-ray and the diffraction X-ray are symmetric with respect to the normal to the film surface. While keeping the angle θ always equal, the X-ray diffraction spectrum is measured by scanning the diffraction angle 2θ between, for example, 10 and 30 °.
In the present embodiment, background correction is not required, and the peak height of the obtained X-ray diffraction spectrum is measured without background correction.

In this embodiment, the polybutylene terephthalate layer A is preferably a single layer. The reasons are as follows.
That is, as described above, the homopolymer of polybutylene terephthalate (PBT) is effective for improving the problem of retort brushing (white spots) due to its high crystallization speed. If the polybutylene terephthalate layer A is formed as a multilayer with a resin other than the PBT homopolymer, the crystallization rate of the resin layer other than the PBT homopolymer is slow and insufficient, and a sufficient water vapor barrier property cannot be secured. As a result, retort brushing (white spots) occurs in the resin layer other than the PBT homopolymer, which is not preferable.

  The thickness of the polybutylene terephthalate layer A formed on the metal plate 1 is preferably 5 to 30 μm from the viewpoint of moldability and retort adhesion during the retort sterilization treatment.

When the thickness of the polybutylene terephthalate layer A is less than 5 μm, the ratio of the metal exposed portion after molding increases, and rust is generated after retort sterilization.
On the other hand, when the thickness of the polybutylene terephthalate layer A exceeds 30 μm, the residual stress in the film is too large, which makes it difficult to ensure retort adhesion and is undesirable from the viewpoint of cost.

  As described above, the polyester resin-coated metal plate in the present embodiment includes the metal plate 1 and the polybutylene terephthalate layer A laminated so as to be in contact with at least one surface of the metal plate 1.

  The polybutylene terephthalate layer A may be laminated on both sides of the metal plate 1 as shown in FIG. As shown in FIG. 2B, a polybutylene terephthalate layer A is laminated on one surface of the metal plate 1, and a polyester resin layer B different from the polybutylene terephthalate layer A is laminated on the other surface. May be.

In the description on the drawings, the thickness of the resin layer and the thickness of the metal plate are schematically illustrated for the sake of convenience, and thus are different from the exact thickness ratio.
Hereinafter, the polyester resin layer B will be described.

<Polyester resin layer B>
Examples of the polyester resin constituting the polyester resin layer B include polyethylene terephthalate resin, polyethylene terephthalate / isophthalate resin in which isophthalic acid is copolymerized, resin in which polyethylene terephthalate and polybutylene terephthalate are blended, and polyethylene in which isophthalic acid is copolymerized. Examples of the resin include a resin in which terephthalate / isophthalate and polybutylene terephthalate are blended. However, the invention is not limited thereto, and a known polyester resin can be applied.

  It is preferable that the polyester resin layer B is laminated in a non-oriented state from the viewpoint of ensuring moldability and retort adhesion in a container having high molding difficulty, for example, a DI (Drawing & Ironing) can. Further, the polyester resin layer B may be a single layer or a multilayer.

  The above-mentioned polyester resin layer B can be blended with known additives, for example, an antiblocking agent, a pigment, an antistatic agent, an antioxidant, a lubricant, and the like by a known formulation.

[Method for producing polyester resin-coated metal plate]
Next, a method for producing a polyester resin-coated metal plate in the present embodiment will be described, but the present invention is not limited to the following description.
The polyester resin-coated metal plate of the present embodiment can be manufactured by forming a polybutylene terephthalate layer A on at least one surface of the metal plate 1 by thermal bonding.

The method for producing a polyester resin-coated metal plate of the present embodiment is characterized in that the X-ray diffraction intensity of the (100) plane and the X-ray of the (1-11) plane in the polybutylene terephthalate layer A after lamination are formed on at least one surface of the metal plate. A method for producing a polyester resin-coated metal sheet, comprising laminating a biaxially stretched polybutylene terephthalate film using a laminating roll so that a diffraction intensity ratio R falls within a range of 1.3 or more and 6.6 or less. Is characterized by having the following steps.
(1) The sheet temperature of the metal plate is set in the range of 240 ° C. to 300 ° C., the surface temperature of the laminating roll is set in the range of 30 ° C. to 180 ° C. A laminating step of laminating the biaxially stretched polybutylene terephthalate film on the metal plate under the condition that the difference from the surface temperature of the roll is maintained at 80 ° C. or more;
(2) after the laminating step, an orientation returning step in which the oriented crystals of the biaxially stretched polybutylene terephthalate film dissolved in the laminating step return due to the influence of the plate temperature immediately after lamination;
(3) A quenching step of quenching the metal plate on which the biaxially stretched polybutylene terephthalate film is laminated after the orientation return step.

However, the X-ray diffraction intensity of the (100) plane is the maximum value at which the diffraction angle 2θ is found in the range of 23.0 ° to 24.0 °, and the X-ray diffraction intensity of the (1-11) plane is The diffraction angle 2θ is the maximum value observed in the range of 25.0 ° to 26.0 °, and the X-ray diffraction intensity ratio R = (100) plane diffraction intensity / (1-11) plane diffraction intensity. is there.
Hereinafter, each step will be described.

First, the laminating step will be described.
As shown in FIG. 3, the metal plate 1 is heated to a temperature of 240 ° C. to 300 ° C. by a heating roll (not shown). Then, the heated metal plate 1 is supplied between the laminating rolls 3A and 3B.
Here, when the heating temperature of the metal plate 1 is lower than 240 ° C., the X-ray diffraction intensity of the (100) plane of the biaxially stretched PBT film remaining after the formation of the polybutylene terephthalate layer A, that is, the amount of oriented crystals is reduced. Since it is too large, it is difficult to make the value of the X-ray diffraction intensity ratio R within a preferable range, which is not preferable.
On the other hand, when the heating temperature of the metal plate 1 exceeds 300 ° C., when the polybutylene terephthalate layer A is laminated, the whole film is in a molten state and is welded to the laminating roll or the surface of the laminating roll is rough. It is not preferable because the degree is transferred.

  Subsequently, the polybutylene terephthalate film A 'for forming the polybutylene terephthalate layer A is rewound from the supply roll and supplied between the laminate rolls 3A and 3B so as to be in contact with one surface of the metal plate 1. The metal plate 1 and the polybutylene terephthalate film A 'are sandwiched between the laminating rolls 3A and 3B to form a polyester resin-coated metal plate.

  In the present embodiment, a known roll can be used as the laminating roll. Known rolls include, for example, fluororubber rolls and silicone rubber rolls. Although the diameter of the laminating roll is not particularly limited, for example, a laminating roll having a diameter of 200 mm to 550 mm can be used.

  Further, it is preferable that the surface temperature of the laminating roll is controlled to a predetermined temperature by a cooling roll or a heating roll (not shown). Although the surface temperature of the laminating roll varies depending on the type of the manufacturing apparatus and the like, in the present embodiment, the temperature is preferably set to 30 ° C. to 180 ° C. in a preferable range of the value of the X-ray diffraction intensity ratio R of the polybutylene terephthalate layer A. It is preferable to set it within.

  Furthermore, in the present embodiment, the laminating speed for producing the polyester resin-coated metal plate is not particularly limited, but is generally preferably 50 mpm to 300 mpm.

Here, the laminating speed is related to the transit time of the nip portion of the laminating roll. That is, when the laminating speed is high, the passing time of the nip is short, and when the laminating speed is low, the passing time of the nip is long.
That is, the passage time of the nip portion is a time during which the polyester resin-coated metal plate is cooled by the laminating roll. Therefore, it can be said that the laminating speed is one of the parameters for controlling the value of the X-ray diffraction intensity ratio R of the polybutylene terephthalate layer A.

In the present embodiment, if the laminating speed is less than 50 mpm, it is not preferable because the time during which the film receives radiant heat from the metal plate immediately before sticking becomes longer and the film wrinkles easily occur.
On the other hand, if the laminating speed exceeds 300 mpm, the amount of air bubbles caught between the metal plate and the film increases significantly, which is not preferable from the viewpoint of corrosion resistance and retort adhesion.

  In addition, at the stage before the thermal bonding, it is preferable that the polybutylene terephthalate film A 'is biaxially stretched by the general method as described above. The degree of biaxial orientation of the biaxially stretched film is not particularly limited.

Further, as shown in FIG. 3, a resin layer may be formed by simultaneously laminating films on both surfaces of the metal plate 1.
In that case, the polybutylene terephthalate layer A may be formed on both surfaces of the metal plate 1.
Alternatively, a polybutylene terephthalate layer A may be formed on one side of the metal plate 1 and a polyester resin layer B different from the polybutylene terephthalate layer A may be provided on the other side. In this case, as shown in FIG. 3, the polyester resin film B ′ to be the polyester resin layer B can be sandwiched between the laminating rolls 3A and 3B in the same manner as the polybutylene terephthalate film A ′ and thermally bonded.

Next, the alignment return step will be described.
As shown in FIG. 3, a quench tank 12 containing cooling water is provided below the laminating rolls 3A and 3B. After the above-described laminating step, the obtained polyester resin-coated metal sheet is sent to the quench tank 12.
The oriented crystals in the polybutylene terephthalate resin layer A are dissolved by the heat in the laminating step. However, as described above, since the homopolymer of polybutylene terephthalate has a very high crystallization rate, the collapsed oriented crystal loses its original orientation until the obtained polyester resin-coated metal plate is sent to the quench tank 12. A phenomenon of returning to the crystalline state occurs (orientation return).

  In the present embodiment, the time T in which the orientation return occurs is defined as the time from immediately after lamination to the time of entering the cooling water of the quench tank. More specifically, as shown in FIG. 3, the Y from the point X immediately after the arbitrary point P of the polyester resin-coated metal plate has come out of the nip portion of the laminating roll to the point at which the cooling water of the quench tank 12 enters is removed. Defined as the time required to move to a point.

In the present embodiment, it is preferable that the time T during which the alignment return occurs is 3 seconds or less.
If the time T during which the orientation return occurs exceeds 3 seconds, the above-described orientation return becomes too large, and it becomes difficult to control the X-ray diffraction intensity ratio R, which is a feature of the present embodiment, to a preferable value.
Therefore, in the present embodiment, it can be said that the time T is preferably set to 3 seconds or less.

Next, the quenching step in the present embodiment will be described.
As described above, the quench tank 12 containing cooling water is provided below the laminating rolls 3A and 3B, as shown in FIG. The obtained polyester resin-coated metal sheet is sent to the quench tank 12 and immediately quenched to 80 ° C. or less, in order to control the X-ray diffraction intensity ratio R, which is a feature of the present embodiment, to a preferable value. Is preferred.
If the cooling temperature is higher than 80 ° C., the orientation return proceeds even after cooling, and the value of the X-ray diffraction intensity ratio R, which is a feature of the present embodiment, may not be able to be controlled to a preferable range. Absent.

  As described above, in the present embodiment, (a) the temperature of the metal plate 1 before the thermal bonding, (b) the surface temperature of the laminating roll, (c) the cooling time at the laminating roll nip portion, and (d) the orientation return occurs. The state of the oriented crystal of the polybutylene terephthalate layer A is controlled by setting each parameter of the time T to an optimum value.

  Then, by setting the value of the X-ray diffraction intensity ratio R of the polybutylene terephthalate layer A within the specified range, a polyester resin-coated metal plate having preferable impact resistance, moldability, retort adhesion, and retort brushing resistance is obtained. What you get.

[container]
Next, a container such as a metal can in this embodiment will be described.
Examples of the container in the present embodiment include, but are not limited to, metal cans such as beverage cans and food cans, square cans, cans, drums, battery cases, and pouches.

  The container of the present embodiment is manufactured by a known can manufacturing method using the above-described polyester resin-coated metal plate. Known methods for making cans include, for example, drawing, drawing and ironing, stretch draw and ironing, and the like.

  In the container of the present embodiment, it is preferable that the above-mentioned polybutylene terephthalate layer A is formed on the outer surface from the viewpoint of suppressing the occurrence of retort brushing (white spots).

In this embodiment, the polybutylene terephthalate layer A may be laminated on both the outer surface and the inner surface of the container.
Alternatively, the above-mentioned polybutylene terephthalate layer A may be formed on the outer surface of the container, and the above-mentioned polyester resin layer B may be laminated on the inner surface.

[Container lid]
Examples of the container lid in the present embodiment include a so-called stay-on-tab type SOT can lid and a full open type easy open can lid (EOE). Alternatively, a three-piece can roof can be mentioned. These can lids can also be manufactured by a known method.

  In the container lid of the present embodiment, it is preferable that the above-mentioned polybutylene terephthalate layer A is formed on the outer surface from the viewpoint of suppressing the occurrence of retort brushing (white spots).

  The above-mentioned polybutylene terephthalate layer A may be laminated on the outer surface and the inner surface of the container lid. Alternatively, a polyester resin layer B may be laminated on the inner surface of the container lid, or a coating film (not shown) may be formed.

  Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to the following examples.

[Production of polyester resin coated metal plate]
As the metal plate, a tin-free steel (TFS) plate having a thickness of 0.225 mm was used.

(Example 1)
As the polybutylene terephthalate layer A, a biaxially stretched polybutylene terephthalate film (trade name: BOBLET) having a thickness of 15 μm from Kojin Film & Chemicals Co., Ltd. was prepared.

  Next, BOBLET 15 μm from Kojin Film & Chemicals Co., Ltd. was brought into contact with both surfaces of a metal plate heated to 260 ° C., sandwiched between a pair of laminating rolls, pressed and laminated, and coated with a polyester resin. A metal plate was produced. In addition, a roll made of fluororubber was used as a laminating roll, and its surface temperature was 180 ° C. The laminating speed was 55 mpm (meter per minute).

  The obtained polyester resin-coated metal plate was immediately sent to a quench tank containing cooling water and cooled. The temperature of the cooling water was 50 ° C, and the temperature of the polyester resin-coated metal plate after cooling in the quench tank was 50 ° C. In addition, the time T during which the alignment return occurred was 3 seconds.

  The X-ray diffraction intensity ratio of the polybutylene terephthalate layer A of the obtained polyester resin-coated metal plate was calculated. The measurement conditions of X-ray diffraction were as follows.

(Calculation of X-ray diffraction intensity ratio by X-ray diffraction)
X-ray diffractometer: RINT-2500 manufactured by Rigaku Corporation
X-ray: CuKα X-ray (wavelength λ = 0.1542 nm)
Tube voltage: 40kV
Tube current: 200mA
Divergence slit: 1/2 °
Light receiving slit: 0.15mm

FIG. 4 shows the obtained X-ray diffraction spectrum. As shown in FIG. 4, as the X-ray diffraction intensity of the (100) plane, 3800 cps, which is the maximum value found in the range of 2θ = 23.0 to 24.0 °, was employed. As the X-ray diffraction intensity of the (1-11) plane, 1900 cps, which is the maximum value found in the range of 2θ = 25.0 ° to 26.0 °, was used. The background correction was not performed (the same applies to other examples and comparative examples).
By the calculation of “(100) plane diffraction intensity / (1-11) plane diffraction intensity”, a value of X-ray diffraction intensity ratio R = 2.0 was obtained. Table 1 shows the results.

(Evaluation of impact resistance)
Paraffin wax is applied to the polyester resin-coated metal plate obtained as described above at a rate of 50 mg / m ^{2 on} each side, and punched into a disk (blank) having a diameter of 142 mm so that the polybutylene terephthalate layer A becomes the outer surface of the can. At the same time, a 1st cup was produced by drawing. The produced 1st cup was subjected to redrawing to prepare a DRD (Draw and Reddraw) cup having a drawing ratio of 2.15.

Ion-exchanged water was put into the obtained cup up to the upper end, and a retort sterilization treatment was performed at 125 ° C. for 45 minutes.
Next, a weight of 172 g from a height of 50 mm was dropped on a punch (tip R = 0.5 mm) at a height of 40 mm from the bottom of the cup using a Dupont impact tester to give a dent. The dents were provided at three locations: the rolling direction of the sheet, the 45 ° direction, and the perpendicular direction.
Thereafter, the ERV (Enamel Rate Value) of the dent portion was measured. At the time of measurement, a solution obtained by diluting a specified electrolytic solution (1% NaCl + surfactant (rapizol, manufactured by NOF Corporation) 200 mg / L) with ethanol at a ratio of 2: 1 was used. A voltage of 6.3 V was applied, the current value after 4 seconds was measured, and evaluation was performed as follows.
◎ ... 0.005mA or less
: More than 0.005 mA and 0.05 mA or less,
△ ・ ・ ・ More than 0.05mA and 0.5mA or less,
× ・ ・ ・ Over 0.5mA

(Formability evaluation)
Paraffin wax was applied to both sides of the obtained polyester resin-coated metal plate at 50 mg / m ^{2 on} each side. After punching into a disk (blank) having a diameter of 151 mm, drawing was performed so that the polybutylene terephthalate layer A became the outer surface of the can, and processed into a 1st cup. Subsequently, a B / M (Body Maker) was used to make a DI can (No. 7 can) with a reduction ratio of 45% at a speed of 200 cpm, and it was confirmed whether or not the outer surface of the can was shaved.
The results were evaluated as follows.
○ ・ ・ ・ At the level where actual production can be performed without external shavings.
×: The level of production of the actual machine is difficult due to the occurrence of external scraping.

(Evaluation of retort adhesion)
The obtained polyester resin-coated metal plate was coated with paraffin wax at 50 mg / m ^{2 on} each side, punched into a disk (blank) having a diameter of 142 mm, and simultaneously drawn to produce a 1st cup. The produced 1st cup was subjected to redrawing to prepare a DRD (Draw and Reddraw) cup having a drawing ratio of 2.15.

Cuts were made on the entire periphery of the obtained cup with a cutter at positions 25 mm and 50 mm from the bottom from the bottom. The cup was submerged in a container filled with water and subjected to a retort sterilization treatment at 125 ° C. for 45 minutes. The maximum peel length of the film at the cut was measured. The evaluation was performed as follows.
◎ ・ ・ ・ Peel length is 5mm or less ○ ・ ・ ・ Peel length is more than 5mm and 10mm or less △ ・ ・ ・ Peel length is more than 10mm and 15mm or less × ・ ・ ・ Peel length is more than 15mm and 20mm or less × ×: The peel length exceeds 20 mm

(Retort brushing evaluation)
The obtained polyester resin-coated metal plate was coated with paraffin wax at 50 mg / m ^{2 on} each side, punched into a disk (blank) having a diameter of 142 mm, and simultaneously drawn to produce a 1st cup. The produced 1st cup was subjected to redrawing to prepare a DRD (Draw and Reddraw) cup having a drawing ratio of 2.15.

120 ml of ion-exchanged water is put into the obtained cup, the cup is put into a SUS punching metal (hole diameter Φ = 5 mm) container, and the temperature is raised at 125 ° C. for 10 minutes in a retort pot having a temperature rising rate of 40 ° C./min. A retort sterilization treatment was performed. The taken out cans were evaluated on a 5-point scale according to the following criteria.
XX: Punch holes are transferred to the entire surface of the cup bottom. X: Punch holes are transferred to almost the entire bottom of the cup (about 80%).
△ ・ ・ ・ Half of the punch holes are transferred to the bottom of the cup ○ ・ ・ ・ Slight punch holes are transferred to the bottom of the cup (less than 20%)
A: No transfer of punch holes on the bottom of the cup The results obtained above are shown in Table 1.

(Example 2)
The operation was performed in the same manner as in Example 1 except that the surface temperature of the laminating roll was set to 150 ° C.
FIG. 5 shows a chart of the obtained X-ray diffraction peak. As shown in FIG. 5, as the X-ray diffraction intensity of the (100) plane, 7500 cps, which is the maximum value found in the range of 2θ = 23.0 to 24.0 °, was adopted. As the X-ray diffraction intensity of the (1-11) plane, 2080 cps, which is the maximum value found in the range of 2θ = 25.0 ° to 26.0 °, was used.
By the calculation of “(100) plane diffraction intensity / (1-11) plane diffraction intensity”, a value of X-ray diffraction intensity ratio R = 3.6 was obtained. Table 1 shows the results.

(Example 3)
The procedure was performed in the same manner as in Example 1 except that the heating temperature of the metal plate before lamination, the surface temperature of the laminating roll, the laminating speed, and the time T during which the orientation was restored were as shown in Table 1.

(Example 4)
The procedure was performed in the same manner as in Example 1 except that the heating temperature of the metal plate before lamination, the surface temperature of the laminating roll, the laminating speed, and the time T during which the orientation was restored were as shown in Table 1.

(Example 5)
Example 1 Example 1 was repeated except that the thickness of the biaxially stretched polybutylene terephthalate film forming the polybutylene terephthalate layer A was 25 μm, the heating temperature of the metal plate before lamination was 275 ° C., and the surface temperature of the laminating roll was 150 ° C. Was performed in the same manner as described above.

(Example 6)
The procedure was performed in the same manner as in Example 5, except that the heating temperature of the metal plate before lamination, the surface temperature of the laminating roll, the laminating speed, and the time T during which the orientation was returned were as shown in Table 1.

(Comparative Example 1)
Example 1 was repeated except that the heating temperature of the metal plate before lamination was 235 ° C and the surface temperature of the laminating roll was 165 ° C.

(Comparative Example 2)
The procedure was performed in the same manner as in Example 1 except that the laminating speed was 40 mpm, the heating temperature of the metal plate before laminating was 240 ° C., the surface temperature of the laminating roll was 150 ° C., and the time T during which the orientation return occurred was 4 seconds. .

(Comparative Example 3)
The procedure was performed in the same manner as in Example 6, except that the laminating speed was 150 mpm, the heating temperature of the metal plate before laminating was 265 ° C., the surface temperature of the laminating roll was 80 ° C., and the time T during which the orientation return occurred was 1 second. .

(Comparative Example 4)
An unstretched two-layer film was prepared as the polybutylene terephthalate layer A. The surface layer of the two-layer film was a polyethylene terephthalate / isophthalate resin in which isophthalic acid was copolymerized at 11 mol%, and the lower layer was a polybutylene terephthalate homopolymer resin.
The heating temperature of the metal plate before the lamination, the surface temperature of the laminating roll, the laminating speed, and the time T during which the orientation was restored were as shown in Table 1. Other than that, it carried out similarly to Example 1.

(Comparative Example 5)
An unstretched two-layer film was prepared as the polybutylene terephthalate layer A. The surface layer of the two-layer film was a homopolymer of polyethylene terephthalate, and the lower layer was a homopolymer of polybutylene terephthalate.
The heating temperature of the metal plate before the lamination, the surface temperature of the laminating roll, the laminating speed, and the time T during which the orientation was restored were as shown in Table 1. Other than that, it carried out similarly to Example 1.

(Example 7)
On one side of the metal plate, a biaxially stretched film made of the same homopolymer of polybutylene terephthalate as in Example 1 was laminated. On the other hand, on the other surface of the metal plate, a biaxially stretched film of a homopolymer of polyethylene terephthalate and a thickness of 12 μm were laminated under the condition that oriented crystals remain.
The heating temperature of the metal plate before the lamination, the surface temperature of the laminating roll, the laminating speed, and the time T during which the orientation return occurs were as shown in Table 2. Other than that, it carried out similarly to Example 1.

(Example 8)
On one side of the metal plate, a biaxially stretched film made of the same homopolymer of polybutylene terephthalate as in Example 1 was laminated. On the other hand, a biaxially stretched film of a polyethylene terephthalate / isophthalate resin in which isophthalic acid was copolymerized at 11 mol% and a thickness of 19 μm were laminated on the other surface of the metal plate under the condition that no oriented crystals remain.
The heating temperature of the metal plate before the lamination, the surface temperature of the laminating roll, the laminating speed, and the time T during which the orientation return occurs were as shown in Table 2. Other than that, it carried out similarly to Example 2.

(Example 9)
On one side of the metal plate, a biaxially stretched film made of the same homopolymer of polybutylene terephthalate as in Example 1 was laminated. On the other hand, on the other surface of the metal plate, a biaxially stretched film made of a blend resin of polyethylene terephthalate and polybutylene terephthalate (blend ratio 4: 6) and a thickness of 18 μm were laminated under the condition that no oriented crystals remain.
The heating temperature of the metal plate before the lamination, the surface temperature of the laminating roll, the laminating speed, and the time T during which the orientation return occurs were as shown in Table 2. Other than that, it carried out similarly to Example 3.

  According to Examples 1 to 6, the polyester resin-coated metal sheet according to the present embodiment showed excellent results in all items of impact resistance, moldability, retort adhesion, and retort brushing resistance.

  On the other hand, according to Comparative Examples 1 to 3, when the value of the X-ray diffraction intensity ratio R of the polybutylene terephthalate layer A is not more than 1.3 and not more than 6.6, the impact resistance, the moldability, the retort adhesion, the retort Unsatisfactory results were obtained in one or more items of the brushing resistance.

  Further, according to Comparative Examples 4 and 5, when the polybutylene terephthalate layer A is a multilayer resin, even when the layer in contact with the metal plate is a homopolymer of polybutylene terephthalate, the crystallization rate of the resin in the surface layer is low. Resulted in retort brushing (white spots).

  According to Examples 7 to 9, when the polybutylene terephthalate layer A was laminated on one side of the metal plate and another polyester resin was laminated on the other side, the lamination conditions were adjusted to conditions suitable for forming the polybutylene terephthalate layer A. Also, the resin layer on the opposite surface was formed well, and the result was practically usable as a container or a container lid.

  In the examples described above, the impact resistance evaluation, the moldability evaluation, the retort adhesion evaluation, and the retort brushing evaluation were evaluated using containers. Generally, it can be said that the container lid has a lower degree of processing than the container. Therefore, if the value of the X-ray diffraction intensity ratio R, which is a feature of the present invention, is within the specified range, the container lid is also evaluated for impact resistance. It can be clearly seen that all of the evaluations of moldability, evaluation of retort adhesion, and evaluation of retort brushing give good results.

  ADVANTAGE OF THE INVENTION According to this invention, generation | occurrence | production of retort brushing (white spot) can be suppressed in the container and container lids, such as a drink can and a food can. Further, it is possible to provide a polyester resin-coated metal plate excellent in impact resistance, moldability, retort adhesion, and the like, and has extremely high industrial applicability.

In this new type of continuous production line, heating and heating are extremely fast, such as dipping the filled containers into high-temperature hot water while transporting them, so that the containers are stacked on the surface of the metal plate more than previously assumed. This is a severe environment for the thermoplastic resin film. A thermoplastic resin film-coated metal that has the property that delamination of a film from a metal plate does not occur even under a severe retort sterilization environment such as a continuous production line with a very high temperature rise rate. Boards are in great demand.

(Evaluation of impact resistance)
A paraffin wax is applied to the polyester resin-coated metal plate obtained as described above at a rate of 50 mg / m ^{2 on} one side, and the polybutylene terephthalate layer A is applied to a disk (blank) having a diameter of 142 mm so as to be the outer surface of the can. At the same time as the removal, a 1st cup was prepared by drawing. The produced 1st cup was subjected to redrawing to prepare a DRD (Draw and Reddraw) cup having a drawing ratio of 2.15.

(Formability evaluation)
Paraffin wax was applied to both sides of the obtained polyester resin-coated metal plate at 50 mg / m ^{2 on} each side. After punching into a disk (blank) having a diameter of 151 mm, drawing was performed so that the polybutylene terephthalate layer A became the outer surface of the can, and processed into a 1st cup. Subsequently, a B / M (Body Maker) was used to make a DI can (No. 7 can) with a reduction ratio of 45% at a speed of 200 cpm, and it was confirmed whether or not the outer surface of the can was shaved.
The results were evaluated as follows.
○ ・ ・ ・ At the level where actual production can be performed without external shavings.
×: The level of production of the actual machine is difficult due to the occurrence of external scraping.

(Evaluation of retort adhesion)
A paraffin wax is applied to the obtained polyester resin-coated metal plate at a rate of 50 mg / m ^{2 on} each side, and punched into a disk (blank) having a diameter of 142 mm so that the polybutylene terephthalate layer A becomes the outer surface of the can. Produced the 1st cup. The produced 1st cup was subjected to redrawing to prepare a DRD (Draw and Reddraw) cup having a drawing ratio of 2.15.

Entire circumference with a cutter to the height 25mm and 50mm position from the bottom on the outside of the resulting cup was scored on. The cup was submerged in a container filled with water and subjected to a retort sterilization treatment at 125 ° C. for 45 minutes. The maximum peel length of the film at the cut was measured. The evaluation was performed as follows.
◎ ・ ・ ・ Peel length is 5mm or less ○ ・ ・ ・ Peel length is more than 5mm and 10mm or less △ ・ ・ ・ Peel length is more than 10mm and 15mm or less × ・ ・ ・ Peel length is more than 15mm and 20mm or less × ×: The peel length exceeds 20 mm

(Retort brushing evaluation)
A paraffin wax is applied to the obtained polyester resin-coated metal plate at a rate of 50 mg / m ^{2 on} each side, and punched into a disk (blank) having a diameter of 142 mm so that the polybutylene terephthalate layer A becomes the outer surface of the can. Produced the 1st cup. The produced 1st cup was subjected to redrawing to prepare a DRD (Draw and Reddraw) cup having a drawing ratio of 2.15.

Claims (9)

A metal plate,
Having a polybutylene terephthalate layer laminated so as to be in contact with at least one surface of the metal plate,
A polyester resin, wherein the ratio (R) of the X-ray diffraction intensity of the (100) plane and the X-ray diffraction intensity of the (1-11) plane in the polybutylene terephthalate layer is in the range of 1.3 to 6.6. Coated metal plate.
(However, the X-ray diffraction intensity of the (100) plane is the maximum value at which the diffraction angle 2θ is found in the range of 23.0 ° to 24.0 °, and the X-ray diffraction intensity of the (1-11) plane is Is the maximum value at which the diffraction angle 2θ is found in the range of 25.0 ° to 26.0 °, and the X-ray diffraction intensity ratio R = (100) plane diffraction intensity / (1-11) plane diffraction intensity Is.) The polybutylene terephthalate layer is laminated on one surface of the metal plate,
The polyester resin-coated metal plate according to claim 1, wherein a polyester resin layer different from the polybutylene terephthalate layer is laminated on the other surface of the metal plate.   The different polyester resin layer is a polyethylene terephthalate resin layer, a polyethylene terephthalate resin layer in which isophthalic acid is copolymerized, a resin layer in which polyethylene terephthalate and polybutylene terephthalate are blended, and a polyethylene terephthalate and polybutylene in which isophthalic acid is copolymerized. The polyester resin-coated metal plate according to claim 2, which is any one selected from a resin layer blended with butylene terephthalate.   The polyester resin-coated metal sheet according to claim 2 or 3, wherein the different polyester resin layers are laminated in a non-oriented state.   The polyester resin-coated metal plate according to any one of claims 1 to 4, wherein the X-ray diffraction intensity ratio R is in a range of 1.3 or more and 3.0 or less.   The polyester resin-coated metal plate according to claim 5, wherein the X-ray diffraction intensity ratio R is in a range of 1.3 or more and 2.7 or less.   A container formed by using the polyester resin-coated metal plate according to claim 1.   A container lid formed by using the polyester resin-coated metal plate according to claim 1. A ratio R of the X-ray diffraction intensity of the (100) plane and the X-ray diffraction intensity of the (1-11) plane of the polybutylene terephthalate layer after lamination is at least 1.3 and not more than 6.6 with respect to at least one surface of the metal plate. A method for producing a polyester resin-coated metal plate by laminating a biaxially stretched polybutylene terephthalate film using a laminating roll to be inside,
The sheet temperature of the metal plate is in the range of 240 ° C. to 300 ° C., and the surface temperature of the laminating roll is in the range of 30 ° C. to 180 ° C. A laminating step of laminating the biaxially stretched polybutylene terephthalate film on the metal plate under the condition that the temperature difference from the temperature is maintained at 80 ° C. or higher,
After the laminating step, an orientation returning step in which the oriented crystals of the biaxially stretched polybutylene terephthalate film dissolved in the laminating step return,
After the orientation return step, a quenching step of quenching the metal plate on which the biaxially stretched polybutylene terephthalate film is laminated,
A method for producing a polyester resin-coated metal sheet, comprising:
(However, the X-ray diffraction intensity of the (100) plane is the maximum value at which the diffraction angle 2θ is found in the range of 23.0 ° to 24.0 °, and the X-ray diffraction intensity of the (1-11) plane is Is the maximum value at which the diffraction angle 2θ is found in the range of 25.0 ° to 26.0 °, and the X-ray diffraction intensity ratio R = (100) plane diffraction intensity / (1-11) plane diffraction intensity Is.)