Resin-coated metal plate for container and method for producing same

Abstract

Provided is a resin-coated metal plate for containers, which is capable of suppressing breakage of a resin coating layer due to can-making processing and scratching of the resin coating layer due to insufficient sliding properties during the can-making processing, and which has excellent adhesion to a printing coating material after the can-making processing. A resin-coated metal plate (1) for containers, which is provided with a polyester resin coating layer (3) on at least one surface of a metal plate (2), said polyester resin coating layer (3) having a half-value width of a peak caused by C = O stretching vibration near 1730 cm-1 as determined by laser Raman spectroscopy of 24 cm-1 to 28 cm-1, and a half-value width of a peak caused by C = O stretching vibration near 1730 cm-1 as determined by laser Raman spectroscopy. The present invention is characterized by containing 0.010-1.0 mass% of an organic lubricant when measured by causing the polarization plane of a linearly polarized laser beam having a wavelength of 532 nm to be incident on the surface of the polyester resin coating layer (3) in parallel with the rolling direction of the metal plate. The contact angle of diiodomethane on the surface of the polyester resin coating layer after heat treatment from room temperature to 240 DEG C within 2 minutes is 23-40 DEG C.

Description

Technical Field

[0001] The present invention relates to a resin-coated metal sheet for containers, the metal sheet having a polyester resin coating layer on at least one surface thereof. Background Art

[0002] Generally speaking, metal containers are roughly divided into two-piece cans and three-piece cans. A two-piece can is a metal container composed of two parts: a can body and a lid body that are integrated with the can bottom. On the other hand, a three-piece can is a metal container composed of three parts: a can body, an upper lid, and a bottom lid. A two-piece can has no welded parts on the can body, so it looks beautiful, but it generally requires a high degree of processing.

[0003] In the past, metal plates such as tin-free steel (TFS) and aluminum used as materials for metal containers were coated for the purpose of improving corrosion resistance. However, the technology for implementing this coating is a complex coating and sintering process, which requires a lot of processing time and discharges a large amount of solvents and carbon dioxide, so there is a problem of heavy environmental load. As a means to solve these problems, a resin-coated metal sheet for containers having a thermoplastic film on the metal surface has been developed, and is currently widely used in industry, mainly for beverage can blanks.

[0004] Patent documents 1 to 3 disclose technologies for manufacturing two-piece cans by drawing and DI (Draw & Ironing) using a resin-coated metal plate having resin coating layers on both sides of the metal plate as a blank. Patent documents 4 and 5 disclose technologies for adding a white pigment to the resin coating layer located on the outer surface side of the metal container after canning in order to enable processing such as printing to improve the appearance of the can body.

[0005] In recent years, with the diversification of can body shapes, the need for a higher degree of processing of can bodies has increased. By reducing the can diameter and increasing the can height, the number of can bodies that can be stored per unit area can be increased. On the other hand, with the higher degree of processing, the resin coating layer of the container resin-coated metal sheet located on the outer surface of the can body may be damaged or scratched, making it impossible to process. In Patent Document 6, as a technology for suppressing scratches on the resin coating layer when manufacturing a two-piece can with a high degree of processing, a technology for adding a lubricant component to the resin coating layer is proposed.

[0006] Prior art literature

[0007] Patent Literature

[0008] Patent Document 1: Japanese Patent Application Laid-Open No. 2-303634

[0009] Patent Document 2: Japanese Patent Application Laid-Open No. 4-91825

[0010] Patent Document 3: Japanese Patent Application Publication No. 2004-148324

[0011] Patent Document 4: Japanese Patent Application Laid-Open No. 8-169098

[0012] Patent Document 5: Japanese Patent Application Publication No. 2004-130536

[0013] Patent Document 6: Japanese Patent Application Publication No. 2017-30210 Summary of the invention

[0014] As described above, in order to suppress scratches on the resin coating layer when manufacturing a two-piece can with a high degree of processing, it is necessary to improve the sliding property of the surface of the resin coating layer by, for example, adding a lubricant component to the resin coating layer.

[0015] On the other hand, the lubricant component hinders the close adhesion of the printing coating used in the printing process, and may also cause poor close adhesion of the printing coating. Therefore, it is necessary to suppress the excessive exudation of the lubricant component to the surface of the resin coating layer (the phenomenon that the additive in the polymer floats to the surface). When the lubricant component floats excessively on the surface of the resin coating layer due to exudation, the lubricant component present on the surface of the resin coating layer repels the printing coating, reducing the close adhesion of the printing coating.

[0016] Furthermore, the resin coating layer is also required to have flexibility so as to be able to follow the canning process with a high degree of processing and, as a result, to suppress the breakage of the resin coating layer.

[0017] In view of such characteristics, conventionally, it has not been possible to obtain a resin-coated metal sheet for a container that achieves all of the following: suppressing breakage and scratching of the resin coating layer during canning processing with a high degree of processing, and improving paint adhesion.

[0018] The present invention has been made in view of the above problems, and an object of the present invention is to provide a resin-coated metal sheet for containers which can suppress breakage and scratching of the resin coating layer accompanying canning processing and has excellent adhesion to a printed coating after canning processing.

[0019] The present inventors have conducted intensive studies to solve the above-mentioned problems and have obtained the following findings.

[0020] In order to suppress the damage of the resin coating layer accompanying the canning process with high processing degree, it is necessary to ensure the softness of the surface of the resin coating layer. It was found that in order to ensure the softness of the surface of the resin coating layer, it is necessary to reduce the crystallinity of the surface of the resin coating layer. As an indicator of the crystallinity of the surface of the resin coating layer, the 1730cm －1 The half value width of the peak due to C═O stretching vibration in the vicinity of φ. By setting the value within a specific range, the damage of the resin coating layer accompanying the can manufacturing process can be suppressed.

[0021] In addition, in order to suppress scratches on the resin coating during canning, it is necessary to improve the sliding properties. In order to improve the sliding properties, it is necessary to add an organic lubricant. On the other hand, as mentioned above, the lubricant component hinders the close adhesion with the printed coating, and may also cause poor close adhesion of the printed coating. Therefore, it is necessary to suppress the excessive oozing of the lubricant component to the surface of the resin coating. The inventors of the present invention have found that when the crystallinity of the surface of the resin coating is high, the oozing of the organic lubricant to the surface of the resin coating is further promoted. That is, in the present invention, it is found that by reducing the crystallinity of the surface of the resin coating, it is possible to take into account both ensuring the softness of the resin coating and suppressing the excessive oozing of the organic lubricant to the surface of the resin coating.

[0022] Furthermore, it is found that the adhesion of the printed coating on the surface of the resin coating layer is mainly to control the affinity with the non-polar liquid. The resin coating layer and the printed coating are closely attached by van der Waals force, and the adhesion with the printed coating can be improved by increasing the van der Waals force component of the surface tension possessed by the resin coating layer. The van der Waals force component of the surface tension can be evaluated by the contact angle with the non-polar liquid, and the larger the van der Waals force component of the surface tension, the smaller the contact angle of the non-polar liquid. The inventors of the present invention have found that by controlling the contact angle of diiodomethane in the resin coating layer after the heat treatment from room temperature to 240°C within 2 minutes to a specific value, a container resin coated metal plate with excellent adhesion with the printed coating can be obtained.

[0023] The present invention has been completed based on the above findings, and the gist of the present invention is as follows.

[0024] [1] A resin-coated metal sheet for a container, comprising a polyester resin coating layer on at least one surface of the metal sheet,

[0025] In the above polyester resin coating layer,

[0026] The 1730 cm －1 The half-value width of the peak caused by the C=O stretching vibration nearby is 24 cm －1 ~28cm －1 The laser Raman spectroscopy is performed by making the polarization plane of a linearly polarized laser with a wavelength of 532 nm parallel to the rolling direction of the metal plate incident on the surface of the polyester resin coating layer for measurement.

[0027] Contains 0.010 mass % to 1.0 mass % of an organic lubricant, and

[0028] The contact angle of diiodomethane on the surface of the polyester resin coating layer after the heat treatment from room temperature to 240° C. over 2 minutes was 23° to 40°.

[0029] [2] The resin-coated metal sheet for a container according to [1], wherein the polyester resin coating layer contains 30% by mass or less of titanium oxide.

[0030] [3] A resin-coated metal sheet for a container, comprising a polyester resin coating layer on at least one surface of the metal sheet,

[0031] In the above polyester resin coating layer,

[0032] having a structure consisting of at least three layers including a topmost layer, an intermediate layer and a bottommost layer,

[0033] The 1730 cm －1 The half-value width of the peak caused by the C=O stretching vibration nearby is 24 cm －1 ~28cm －1 The laser Raman spectroscopy is performed by making the polarization plane of a linearly polarized laser with a wavelength of 532 nm parallel to the rolling direction of the metal plate incident on the surface of the outermost layer for measurement.

[0034] The contact angle of diiodomethane on the surface of the outermost layer after heat treatment from room temperature to 240° C. within 2 minutes was 23° to 40°.

[0035] The outermost layer contains 0.010 mass % to 1.0 mass % of an organic lubricant.

[0036] The outermost layer and the lowermost layer each contain 0% to 2.0% by mass of titanium oxide, and the intermediate layer contains 10% to 30% by mass of titanium oxide.

[0037] The film thickness of the outermost layer and the lowermost layer is 1.0 μm to 5.0 μm, respectively, and the film thickness of the intermediate layer is 6.0 μm to 30 μm.

[0038] [4] The resin-coated metal sheet for a container according to any one of [1] to [3], wherein the polyester resin coating layer is composed of a resin material containing 90 mol % or more of ethylene terephthalate units.

[0039] [5] The resin-coated metal sheet for a container according to any one of [1] to [4], wherein the organic lubricant comprises an acid-modified polyolefin or an oxidized polyolefin having an acid value of 1.0 mgKOH / g to 100 mgKOH / g.

[0040] [6] A method for producing a resin-coated metal sheet for a container, which is the method for producing a resin-coated metal sheet for a container according to [1] or [2] above,

[0041] A polyester resin coating layer containing 0.010 mass % to 1.0 mass % of an organic lubricant is pressed onto a metal plate, and then

[0042] The surface of the polyester resin coating layer is maintained at a temperature not lower than the melting start temperature of the polyester resin coating layer for 0.50 seconds or more, and then cooled at a cooling rate of not lower than 150° C. / second.

[0043] [7] The method for producing a resin-coated metal sheet for a container according to [6], wherein the polyester resin coating layer contains 30% by mass or less of titanium oxide.

[0044] [8] A method for producing a resin-coated metal sheet for a container, which is the method for producing a resin-coated metal sheet for a container according to [3] above,

[0045] A polyester resin coating layer is crimped onto a metal plate, wherein the polyester resin coating layer has a structure consisting of at least three layers including an outermost layer, an intermediate layer, and a lowermost layer, wherein the outermost layer contains 0.010 mass % to 1.0 mass % of an organic lubricant, the outermost layer and the lowermost layer each contain 0 mass % to 2.0 mass % of titanium oxide, and the intermediate layer contains 10 mass % to 30 mass % of titanium oxide, and then,

[0046] After the surface of the outermost surface layer is maintained at a temperature higher than the melting start temperature of the outermost surface layer for 0.50 seconds or longer, it is cooled at a cooling rate of 150° C. / second or higher.

[0047] [9] The method for producing a resin-coated metal sheet for a container according to any one of [6] to [8], wherein the polyester resin coating layer is composed of a resin material containing 90 mol % or more of ethylene terephthalate units.

[0048]

[10] The method for producing a resin-coated metal sheet for a container according to any one of [6] to [9], wherein the organic lubricant comprises an acid-modified polyolefin or an oxidized polyolefin having an acid value of 1.0 mgKOH / g to 100 mgKOH / g.

[0049] According to the present invention, it is possible to provide a resin-coated metal sheet for containers which can suppress breakage and scratching of the resin coating layer accompanying can-making processing and has excellent adhesion to a printed coating after can-making processing. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 It is a cross-sectional view showing the structure of a resin-coated metal sheet for a container as one embodiment of the present invention.

[0051] Figure 2 This is a cross-sectional view showing the structure of a resin-coated metal sheet for a container according to another embodiment of the present invention. DETAILED DESCRIPTION

[0052] Hereinafter, a resin-coated metal sheet for a container which is one embodiment of the present invention will be described.

[0053] Figure 1 1 is a cross-sectional view showing the structure of a resin-coated metal plate for a container as one embodiment of the present invention. Figure 1 As shown, a resin-coated metal plate 1 for a container as one embodiment of the present invention comprises a metal plate 2, a polyester resin coating layer 3 (hereinafter sometimes simply referred to as a resin coating layer 3) formed on the surface side of the metal plate 2, and a resin coating layer 4 formed on the back side of the metal plate 2. The resin coating layers 3 and 4 respectively become the outer surface side and the inner surface side of the metal container after canning.

[0054] In this embodiment, the metal plate 2 is formed of a steel plate such as tinplate or tin-free steel. As tinplate, it is preferable to use a tinplate with a coating amount of 0.5 g / m 2 ~15g / m 2 Tinplate. Wuxi steel preferably has an adhesion of 50mg / m 2 ~200g / m 2 The metal chromium layer and the metal chromium conversion adhesion amount is 3mg / m 2 ~30g / m 2 The type of steel sheet has no particular problem as long as it can be formed into a target shape, but the following components and production methods are preferred.

[0055] (1) Using low carbon steel having a C (carbon) content in the range of more than 0.003 mass % and not more than 0.10 mass %, recrystallization annealing is performed by continuous annealing.

[0056] (2) Using low carbon steel having a C content in the range of more than 0.003 mass % and not more than 0.10 mass %, recrystallization annealing and overaging treatment are performed by continuous annealing.

[0057] (3) Using low carbon steel having a C content in the range of more than 0.003 mass % and not more than 0.10 mass %, recrystallization annealing is performed by box annealing.

[0058] (4) Low carbon steel having a C content in the range of more than 0.003 mass % and not more than 0.10 mass % is used, and recrystallization annealing is performed by continuous annealing or box annealing, followed by secondary cold rolling (DR (Double Reduced) rolling).

[0059] (5) Recrystallization annealing is performed by continuous annealing using IF (Interstitial Free) steel in which an element that fixes solid solution C, such as Nb and Ti, is added to an ultra-low carbon steel having a C content of approximately 0.003 mass % or less.

[0060] The mechanical properties of the steel sheet are not particularly limited as long as it can be formed into the target shape. In order to ensure sufficient can strength without compromising processability, it is preferred to use a steel sheet with a yield point (YP) of 220 MPa to 580 MPa. In addition, the Lankford value (r value), which is an index of plastic anisotropy, is preferably 0.8 or more. Furthermore, the absolute value of the in-plane anisotropy Δr of the r value is preferably 0.7 or less.

[0061] The composition of the steel used to achieve the above characteristics is not particularly limited, for example, as long as it contains Si, Mn, P, S, Al, N and other components. Preferably, the Si content is 0.001% to 0.1% by mass, the Mn content is 0.01% to 0.6% by mass, the P content is 0.002% to 0.05% by mass, the S content is 0.002% to 0.05% by mass, the Al content is 0.005% to 0.100% by mass, and the N content is 0.0005% to 0.020% by mass. The remainder can be Fe and unavoidable impurities. In addition, other components such as Ti, Nb, B, Cu, Ni, Cr, Mo, and V may also be contained, but from the viewpoint of ensuring corrosion resistance, the content of these components is preferably less than 0.02% by mass in total.

[0062] In the present invention, the surface of at least one side of the polyester resin coating layer 3 (the resin coating layer that becomes the outer surface of the container by molding) is analyzed by laser Raman spectroscopy at 1730 cm －1 The half-value width of the peak caused by the C=O stretching vibration nearby is 24 cm －1 ~28cm －1 The laser Raman spectroscopy is performed by making the polarization plane of linearly polarized laser light with a wavelength of 532 nm incident in parallel with the rolling direction of the metal plate (steel plate).

[0063] It is known that the Raman shift determined by laser Raman spectroscopy is 1730 cm －1 The half-value width of the peak based on C=O stretching vibration near 1730 cm is related to the density of the polyester resin (J. Polymer Science 10.317.1972.). In addition, it is known that there is a correlation between the density of the resin and the volume fraction crystallinity (Solid Structure of Polymers II (Kyoritsu Publishing, 1984)). Therefore, by measuring 1730 cm －1The half-value width of the peak due to C=O stretching vibration near 1730 cm-1 can be used to determine the crystallinity of the polyester via the density of the polyester. －1 The half-value width of the peak based on the C═O stretching vibration in the vicinity is used as an indicator of the crystallinity of the surface of the resin coating layer.

[0064] At 1730cm －1 The half-value width of the peak due to the C=O stretching vibration near the ions (hereinafter also referred to as the half-value width of the peak) is 24 cm －1 ~28cm －1 In the case of , the crystallinity of the surface of the resin coating layer 3 is low, and a resin coating layer with high flexibility can be obtained. It should be noted that when the half-value width of the peak is less than 24 cm －1 When the peak half-value width is less than 22 cm, the organic lubricant cannot be prevented from seeping out, and the adhesion of the printed coating is poor. －1 In such a case, the surface flexibility of the resin coating layer 3 is poor, and thus the resin coating layer 3 cannot follow the deformation during canning processing, resulting in damage to the resin coating layer 3.

[0065] In addition, from the viewpoint of suppressing excessive oozing of the organic lubricant to the surface of the resin coating layer 3, it is very important that the surface crystallinity of the resin coating layer 3 is low. If the crystallinity of the resin coating layer 3 becomes high, the oozing of the organic lubricant present in the resin coating layer 3 is promoted, and the contact angle of diiodomethane described later cannot be controlled within the range specified in the present invention, thereby reducing the adhesion of the printed coating. Therefore, from the viewpoint of the adhesion of the printed coating, the Raman shift of 1730 cm －1 The half-value width of the peak caused by the C=O stretching vibration near the －1 ~28cm －1 The half-value width of the peak is more preferably 25 cm －1 ~28cm －1 Here, since the 1730cm －1 The half-value width of the peak caused by the C=O stretching vibration nearby is 28 cm －1 , so the upper limit of the half-value width in the present invention is 28cm －1 In addition, the half-value width of the peak can be measured in detail by the method described in the Examples.

[0066] The resin-coated metal plate 1 for a container is produced by respectively pressing the resin coating layers 3 and 4 onto the front and back sides of a metal plate 2 heated to a temperature above the melting point of the resin coating layers 3 and 4 using a laminating roller, and then cooling the metal plate 2. The crystallinity of the surface of the resin coating layer 3 can be adjusted by changing the surface temperature of the resin coating layer 3 after pressing and the time for which the surface temperature of the resin coating layer 3 after pressing is maintained above the melting start temperature of the resin coating layer 3.

[0067] In order to control the crystallinity of the surface of the resin coating layer 3 to be within the range specified in the present invention, it is necessary to quench the surface of the resin coating layer 3 after the resin coating layer 3 is crimped to the metal plate 2, and the surface of the resin coating layer 3 is kept at a temperature above the melting start temperature of the resin coating layer 3 for more than 0.50 seconds. After the resin coating layer 3 is crimped to the metal plate 2, when the time for which the surface of the resin coating layer 3 is kept at a temperature above the melting start temperature of the resin coating layer 3 is less than 0.50 seconds, the surface of the resin coating layer 3 is not fully melted, and the crystallinity of the surface specified in the present invention cannot be obtained. On the other hand, when the surface of the resin coating layer 3 is kept at a temperature above the melting start temperature of the resin coating layer 3 for more than 3.0 seconds after the resin coating layer 3 is crimped to the metal plate 2, the production line becomes longer and the productivity is significantly reduced. Therefore, after the resin coating layer 3 is crimped to the metal plate 2, the time for which the surface of the resin coating layer 3 is kept at a temperature above the melting start temperature of the resin coating layer 3 is preferably less than 3.0 seconds.

[0068] It should be noted that rapid cooling refers to cooling the surface of the resin coating layer 3 from the melting start temperature of the resin coating layer 3 to 120°C at a cooling rate of 150°C / sec or more. The cooling rate is preferably 200°C / sec or more. After the surface of the resin coating layer 3 is maintained at a temperature above the melting start temperature of the resin coating layer 3, when the temperature reaches a temperature below the melting start temperature by naturally cooling, the surface of the resin coating layer 3 is crystallized, and the crystallinity of the present invention cannot be obtained.

[0069] Furthermore, during the period from when the resin coating layer 3 is crimped to the metal plate 2 until it is quenched, it is necessary to avoid contact between the resin coating layer 3 and a roller or the like. When the resin coating layer 3 contacts a roller or the like whose melting start temperature is lower than the melting start temperature of the resin coating layer 3, the surface of the resin coating layer 3 is cooled and drops to a temperature lower than the melting start temperature of the resin coating layer 3, and the crystallinity of the surface of the resin coating layer 3 cannot be controlled to be within the range specified in the present invention. In addition, when the resin coating layer 3 contacts a roller or the like whose melting point is higher than the melting point, welding to the roller occurs. Therefore, during the period from when the resin coating layer 3 is crimped to the metal plate 2 until it is quenched, it is necessary to avoid contact between the resin coating layer 3 and a roller or the like.

[0070] In order to increase the surface temperature of the resin coating layer 3 after being crimped to the metal plate 2, there are methods of increasing the heating temperature of the metal plate 2 before crimping, reducing the pressure of the laminating roller during crimping, and increasing the temperature of the laminating roller during crimping. In order to obtain the crystallinity as the target of the present invention, the heating temperature of the metal plate 2 is preferably about 20°C to 50°C higher than the melting point of the resin coating layer 3. In addition, by reducing the pressing pressure of the roller during crimping, the cooling effect brought by the roller during crimping can be reduced, and the surface temperature of the resin coating layer 3 after crimping can be kept high. In addition, the higher the temperature of the laminating roller, the more the cooling effect brought by the roller during crimping can be reduced, and the surface temperature of the resin coating layer 3 after crimping can be kept high. However, if the temperature of the laminating roller becomes a temperature higher than the glass transition temperature of the resin coating layer 3 + 60°C, the roughness of the laminating roller is transferred with the softening of the resin coating layer 3, resulting in appearance defects. Therefore, the temperature of the laminating roller needs to be below the glass transition temperature of the resin coating layer 3 + 60°C.

[0071] In order to improve the sliding property during canning, the resin coating layer 3 contains an organic lubricant in the range of 0.010 mass% to 1.0 mass%. When the content of the organic lubricant is less than 0.010 mass%, sufficient sliding property cannot be ensured during canning, and the resin coating layer 3 is scratched. In addition, when the content of the organic lubricant exceeds 1.0 mass%, the proportion of the organic lubricant in the resin coating layer 3 becomes large, thereby causing the embrittlement of the resin coating layer 3, and scratches occur during canning. The content of the organic lubricant is preferably 0.020 mass% or more. In addition, the content of the organic lubricant is preferably 0.90 mass% or less, and more preferably 0.80 mass% or less.

[0072] The organic lubricant contained in the resin coating layer 3 preferably includes an acid-modified polyolefin with an acid value of 1.0 mgKOH / g to 100 mgKOH / g or an oxidized polyolefin with an acid value of 1.0 mgKOH / g to 100 mgKOH / g. By controlling the acid value of the organic lubricant, the seepage behavior of the organic lubricant to the surface of the resin coating layer 3 can be adjusted. The lower the acid value of the organic lubricant, the easier it is to seep out to the surface of the resin coating layer 3 during heat treatment, and the higher the acid value of the organic lubricant, the less likely it is to seep out to the surface of the resin coating layer 3 during heat treatment. If the acid value of the organic lubricant contained in the resin coating layer 3 is 1.0 mgKOH / g or more, excessive seepage to the surface of the resin coating layer 3 accompanying the heat treatment can be more effectively suppressed. In addition, if the acid value of the organic lubricant contained in the resin coating layer 3 is 100 mgKOH / g or less, a more appropriate amount of seepage to the surface of the resin coating layer 3 can be obtained, and scratches during canning can be more effectively suppressed. The acid value of the organic lubricant is more preferably 2.0 mgKOH / g or more, and further preferably 10 mgKOH / g or more. In addition, the acid value of the organic lubricant is more preferably 80 mgKOH / g or less, and further preferably 60 mgKOH / g or less. It should be noted that the acid value of the organic lubricant can be measured according to JIS K5902.

[0073] In addition, the melting point of the organic lubricant is preferably 80°C to 230°C. If the melting point of the organic lubricant is 80°C or higher, the oozing of the organic lubricant to the surface of the resin coating layer 3 can be more effectively suppressed. On the other hand, if the melting point of the organic lubricant is 230°C or lower, better sliding properties can be obtained during processing. The melting point of the organic lubricant is more preferably 90°C or higher, and more preferably 100°C or higher. In addition, the melting point of the organic lubricant is more preferably 200°C or lower, and more preferably 180°C or lower.

[0074] In the present invention, the contact angle of diiodomethane on the surface of the resin coating layer 3 after the resin coating layer 3 is subjected to a heat treatment from room temperature (normal temperature) to 240°C within 2 minutes is 23° to 40°. Here, the heat treatment from room temperature to 240°C within 2 minutes refers to a heat treatment in which the temperature of the container resin-coated metal plate 1 becomes 240°C (reaches 240°C) within 2 minutes from the start of the heat treatment (room temperature). It should be noted that the room temperature is not particularly limited, and as an example, it is 20°C ± 15°C. This heat treatment simulates the heat treatment performed after processing in order to improve the close fit between the resin coating layer and the metal plate when manufacturing the can body on the canning line. The contact angle of diiodomethane is related to the van der Waals force component of the surface tension of the resin coating layer 3. The larger the contact angle of diiodomethane, the smaller the van der Waals force component of the surface tension of the resin coating layer 3. Therefore, when the contact angle of diiodomethane exceeds 40°, the adhesive force generated by the van der Waals force between the printed coating becomes smaller, and the printed coating peels off. In addition, when the contact angle of diiodomethane is less than 23°, there is almost no organic lubricant on the surface of the resin coating layer 3, and scratches during canning cannot be suppressed. Therefore, the contact angle of diiodomethane on the surface of the resin coating layer 3 after the above-mentioned heat treatment must be 23° to 40°. The above-mentioned contact angle is preferably 25° or more, and more preferably 27° or more. In addition, the above-mentioned contact angle is preferably 38° or less, more preferably 36° or less, and further preferably 29° or less. It should be noted that the contact angle of diiodomethane can be measured by the method described in the examples in detail. It should be noted that in the present invention, by controlling the half-value width (crystallinity) of the peak and the organic lubricant content, the contact angle of diiodomethane described above can be set to the desired contact angle of diiodomethane. In the case where the resin coating layer 3 does not contain an organic lubricant, even if the crystallinity is controlled, there is no organic lubricant on the surface of the resin coating layer 3, so the contact angle of diiodomethane on the surface of the resin coating layer 3 becomes smaller, and scratches on the resin coating layer 3 occur.

[0075] The resin coating layer 3 is preferably formed of a resin material having 90 mol% or more of ethylene terephthalate units. Specifically, the resin coating layer 3 is preferably a polyester having 90 mol% or more of ethylene terephthalate units constituting polyethylene terephthalate, wherein the polyethylene terephthalate is composed of terephthalic acid as a carboxylic acid component and ethylene glycol as a glycol component. The resin coating layer 3 is more preferably formed of a resin material having 92 mol% or more of ethylene terephthalate units. It is further preferably formed of a resin material having 92 mol% to 97 mol% of ethylene terephthalate units. If the ethylene terephthalate units are 90 mol% or more, higher heat can be tolerated for the heat generated during the continuous canning process.

[0076] Various dicarboxylic acid components and diol components can be used in the raw materials of polyester resin. In addition, multiple dicarboxylic acid components and diol components can be copolymerized within the range that does not damage heat resistance and processability. As dicarboxylic acid components, aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, naphthalene dicarboxylic acid, diphenyl dicarboxylic acid, diphenyl sulfone dicarboxylic acid, diphenoxy ethane dicarboxylic acid, 5-sodium sulfoisophthalic acid, phthalic acid, oxalic acid, succinic acid, adipic acid, sebacic acid, dimer acid, maleic acid, fumaric acid, aliphatic dicarboxylic acids such as cyclohexane dicarboxylic acid, hydroxycarboxylic acids such as p-hydroxybenzoic acid, etc. can be exemplified. As diol components, aliphatic diols such as ethylene glycol, propylene glycol, butanediol, pentanediol, hexanediol, neopentyl glycol, aliphatic diols such as cyclohexanedimethanol, aromatic diols such as bisphenol A and bisphenol S, and diethylene glycol can be exemplified.

[0077] The resin material forming the resin coating layer 3 is not limited by its preparation method. For example, the resin material can be formed by the following method: terephthalic acid, ethylene glycol and copolymer components are subjected to esterification reaction, and then the obtained reaction product is subjected to polycondensation reaction to form a copolyester. Alternatively, the resin material can be formed by the following method: dimethyl terephthalate, ethylene glycol and copolymer components are subjected to ester exchange reaction, and then the obtained reaction product is subjected to polycondensation reaction to form a copolyester. In addition, in the manufacture of polyester, additives such as fluorescent whitening materials, antioxidants, heat stabilizing materials, ultraviolet absorbers, antistatic materials, etc. can also be added as needed.

[0078] In order to improve the appearance after printing, the resin coating layer 3 is sometimes required to be white. In this case, titanium oxide of less than 30% by mass can be contained in the resin coating layer 3 as an arbitrary component. The content of titanium oxide is preferably more than 10% by mass, and more preferably more than 12% by mass. In addition, the content of titanium oxide is more preferably less than 25% by mass, and further preferably less than 20% by mass. If the content of titanium oxide is more than 10% by mass, a more excellent whiteness after processing can be obtained. In addition, if the content of titanium oxide is less than 30% by mass, even in the molding with a high degree of processing, better adhesion between the metal plate 2 and the resin coating layer 3 and better processability of the resin coating layer 3 can be obtained.

[0079] The titanium oxide added to the resin coating layer 3 is not particularly limited, but preferably the rutile titanium oxide has a purity of 90% or more because it has better dispersibility when mixed with the resin material.

[0080] It should be noted that the resin material forming the resin coating layer 4 (which becomes the resin coating layer on the inner surface side of the container by molding) may be the same resin material as the resin material forming the above-mentioned resin coating layer 3. In particular, it is preferred that the polyester has 90 mol% or more of ethylene terephthalate units constituting polyethylene terephthalate, wherein the polyethylene terephthalate is composed of terephthalic acid as a carboxylic acid component and ethylene glycol as a diol component. It should be noted that the resin coating layer 4 may have the same structure as the resin coating layer 3, or may be different.

[0081] As an example of a preferred method for manufacturing a resin-coated metal plate for a container according to the present embodiment, the following manufacturing method can be cited: a polyester resin coating layer (resin material forming the polyester resin coating layer) is crimped onto a metal plate, and then the surface of the polyester resin coating layer is kept at a temperature above the melting start temperature of the polyester resin coating layer for more than 0.50 seconds, and then cooled at a cooling rate of more than 150°C / second. The polyester resin coating layer contains 0.010% to 1.0% by mass of an organic lubricant. In addition, the polyester resin coating layer is preferably composed of a resin material containing 90 mol% or more of ethylene terephthalate units. The organic lubricant preferably contains an acid-modified polyolefin or an oxidized polyolefin having an acid value of 1.0 mgKOH / g to 100 mgKOH / g.

[0082] Next, another embodiment of the resin-coated metal sheet for containers of the present invention is described. The resin-coated metal sheet for containers of this embodiment includes a polyester resin coating layer on at least one surface of the metal sheet, and the polyester resin coating layer has at least three layers of an outermost layer, an intermediate layer, and a lowermost layer.

[0083] Figure 2 1 is a cross-sectional view showing the structure of a resin-coated metal plate 10 for containers as an example of the present embodiment. In the present embodiment, components corresponding to those of the resin-coated metal plate 1 for containers are denoted by the same reference numerals and detailed description thereof is omitted.

[0084] Figure 2 The resin-coated metal plate 10 for a container shown is different from the above-mentioned resin-coated metal plate 1 for a container in that the polyester resin coating layer 30 (hereinafter sometimes simply referred to as the resin coating layer 30) formed on the surface side of the metal plate 2 is composed of multiple polyester resin coating layers (the outermost layer 30a, the middle layer 30b, and the lowermost layer 30c).

[0085] In the resin-coated metal sheet 10 for a container, the configurations of the metal sheet 2 and the resin coating layer 4 are respectively the same as those of the metal sheet 2 and the resin coating layer 4 of the resin-coated metal sheet 1 for a container described above.

[0086] The laser Raman spectroscopic analysis method was used to determine the 1730 cm-1 value of the resin coating layer 30 on at least one side of the resin-coated metal plate 10 for a container (the resin coating layer that becomes the outer surface of the container by molding). －1 The half-value width of the peak caused by the C=O stretching vibration near the resin coating layer 3 of the resin-coated metal plate 1 for the container is the same as that of the resin coating layer 3 of the resin-coated metal plate 1 for the container. The laser Raman spectroscopic analysis method is to make the polarization plane of the linear polarized laser with a wavelength of 532nm parallel to the rolling direction of the metal plate incident on the surface of the resin coating layer 30 (i.e., the surface of the outermost layer 30a) and measure it. That is, the half-value width of the peak is 24cm －1 ~28cm －1 .

[0087] The contact angle of diiodomethane on the surface of the resin coating layer 30 (i.e., the surface of the outermost layer 30a) after the resin coating layer 30 was subjected to heat treatment from room temperature (normal temperature) to 240°C within 2 minutes was the same as that of the resin coating layer 3 of the resin-coated metal plate 1 for a container. That is, the contact angle was 23° to 40°.

[0088] The outermost layer 30a has the same structure as the above-mentioned resin coating layer 3. That is, the outermost layer 30a is made of the same resin material as the resin coating layer 3, and contains 0.010 mass % to 1.0 mass % of an organic lubricant.

[0089] In addition, examples of the resin material forming the intermediate layer 30 b and the lowermost layer 30 c include the same resin materials as those forming the above-mentioned resin coating layer 3 .

[0090] In the resin-coated metal sheet 10 for containers, the film thickness of the outermost layer 30a and the lowermost layer 30c is preferably 1.0 μm to 5.0 μm, respectively. The film thickness of the outermost layer 30a and the lowermost layer 30c is more preferably 1.5 μm or more, and further preferably 2.0 μm or more. In addition, the film thickness of the outermost layer 30a and the lowermost layer 30c is more preferably 4.0 μm or less, and further preferably 3.0 μm or less. The film thickness of the intermediate layer 30b is preferably 6.0 μm to 30 μm. The film thickness of the intermediate layer 30b is more preferably 8.0 μm or more, and further preferably 10 μm or more. In addition, the film thickness of the intermediate layer 30b is more preferably 25 μm or less, and further preferably 20 μm or less. In the case of adding titanium oxide to the resin coating layer 30, from the viewpoint of suppressing the embrittlement of the outermost layer 30a, the amount of titanium oxide contained in the outermost layer 30a is preferably 0 mass % to 2.0 mass % relative to the outermost layer 30a. In addition, from the viewpoint of suppressing the decrease in the adhesion between the bottom layer 30c and the metal plate 2, the amount of titanium oxide contained in the bottom layer 30c is preferably 0% to 2.0% by mass relative to the bottom layer 30c. In addition, from the viewpoint of ensuring the whiteness after processing, the amount of titanium oxide contained in the middle layer 30b is preferably 10% to 30% by mass relative to the middle layer 30b.

[0091] It should be noted that the resin-coated metal plate 10 for containers can be made in the same manner as the resin-coated metal plate 1 for containers. That is, a resin coating layer 30 consisting of a topmost layer 30a, an intermediate layer 30b, and a bottommost layer 30c is formed in advance by a known method. For example, after the same or different polyester resins are melted in multiple extruders (single-axis or double-axis extruders), molten resin films (30a to c) are co-extruded from a T-die and stacked into three layers. Then, any of an unstretched film solidified and wound by a cooling roller, and a film (longitudinal uniaxial stretch film, transverse uniaxial stretch film, sequential biaxial stretch film, simultaneous biaxial stretch film, etc.) formed by stretching the cooled and solidified film can be used as a resin layer. The resin coating layers 30 and 4 are respectively pressed onto the front and back surfaces of the metal plate 2 heated to above the melting point of the resin coating layers 30 and 4 by laminating rollers, and then cooled, thereby making it. At this time, the crystallinity of the surface of the resin coating layer 30 (that is, the surface of the outermost layer 30 a ) can be adjusted in the same manner as in the above-mentioned resin-coated metal sheet 1 for a container.

[0092] As an example of a preferred method for manufacturing a resin-coated metal plate for a container of the present embodiment, the following method can be cited: a polyester resin coating layer (resin layer forming a polyester resin coating layer) having a structure consisting of at least three layers of an outermost layer, an intermediate layer and a lowermost layer is crimped onto a metal plate, and then the surface of the outermost layer is kept at a temperature above the melting start temperature of the outermost layer for more than 0.50 seconds, and then cooled at a cooling rate of more than 150°C / second. The outermost layer contains 0.010% to 1.0% by mass of an organic lubricant. In addition, it is preferred that the outermost layer and the lowermost layer each contain 0% to 2.0% by mass of titanium oxide, and the intermediate layer contains 10% to 30% by mass of titanium oxide. The polyester resin coating layer is preferably composed of a resin material having 90 mol% or more of ethylene terephthalate units. The organic lubricant preferably contains an acid-modified polyolefin or an oxidized polyolefin having an acid value of 1.0 mgKOH / g to 100 mgKOH / g.

[0093] The resin-coated metal sheet for containers of the present embodiment also provides the same effects as those of the resin-coated metal sheet for containers 1 described above.

[0094] Example

[0095] As the metal plate, TFS (Tin Free Steel, metal Cr layer: 120 mg / m2) with a thickness of 0.22 mm was used. 2 , Cr oxide layer: 10 mg / m2 in terms of metal Cr 2 , tempering degree: T3CA), the resin coating layers shown in Tables 1 to 4 are formed by a film lamination method (film hot melt method). For Examples 1 to 24, Comparative Examples 1, 6, and 9, resin-coated metal plates for containers having resin coating layers on both sides of a metal plate are manufactured by the following method. The metal plate is heated to a temperature 20 to 40°C higher than the melting point of the resin coating layer, and a film-like resin coating layer produced by a biaxial stretching method is hot-pressed onto the metal plate using a laminating roller. Then, the surface of the resin coating layer (the outermost layer when multiple layers) located on the outer surface side of the container after canning is maintained at a temperature above the melting start temperature of the resin coating layer (the outermost layer when multiple layers) for 0.50 to 3.0 seconds, followed by rapid cooling (water cooling). In addition, for Comparative Examples 2 to 5, 7, and 8, resin-coated metal plates for containers having resin coating layers on both sides of a metal plate are manufactured by the following method. After the film is hot-pressed, the surface of the resin coating layer (the outermost layer when multiple layers) located on the outer surface side of the container after canning is maintained at a temperature above the melting start temperature of the resin coating layer (the outermost layer when multiple layers) for less than 0.50 seconds, followed by rapid cooling (water cooling).

[0096] The obtained resin-coated metal plate for a container was measured for the 1730 cm-1 concentration determined by laser Raman spectroscopy by the following method. －1 The half-value width of the peak caused by the nearby C=O stretching vibration and the contact angle of diiodomethane.

[0097] <1730cm determined by laser Raman spectroscopy －1 The half-value width of the peak caused by the C=O stretching vibration near

[0098] The surface of the resin coating layer on the outer surface of the container after canning of the resin-coated metal plate for the container was taken as the measurement object, and the measurement was performed by laser Raman spectroscopy using linearly polarized laser. The polarization direction of the laser was parallel to the rolling direction of the metal plate (steel plate) for measurement. The peak for the half-value width measurement was the peak with a Raman shift of 1730 cm －1 The peak is caused by the stretching vibration of C=O near the surface. A laser Raman spectrometer (RAMAN force manufactured by Nanophoton Corporation) was used for the measurement. The incident light used a laser with a wavelength of 532 nm. The measurement conditions were a laser intensity of 6.0 mW, a slit width of 50 μm, a diffraction grating of 600 gr / mm, and a cumulative number of 1. 10 points × 10 points were measured at 5 μm intervals, a total of 100 points, and the 1730 cm peak was obtained from the average spectrum. －1 The half-value width of the peak caused by the C=O stretching vibration near 1730cm －1 The pseudo-Voigt function was used for curve fitting of the half-value width of the peak due to the nearby C=O stretching vibration.

[0099] <Contact angle of diiodomethane>

[0100] The container resin-coated metal plate was heat treated in a hot air drying furnace from room temperature to 240°C within 2 minutes, and cooled to room temperature. Then, the contact angle of diiodomethane was measured on the surface of the resin coating layer that became the outer surface of the container after canning. Using a CA-DT contact angle meter manufactured by Kyowa Interface Science Co., Ltd., a 2 μL drop of diiodomethane was dropped onto the surface of the resin coating layer under an environment of 20°C, and the static contact angle was calculated by the θ / 2 method 1 second after the drop.

[0101] In addition, the obtained resin-coated metal plate for containers was evaluated for processability (breakage resistance), scratch resistance, and print coating adhesion by the methods shown below.

[0102] (1) Processability

[0103] After coating the container with paraffin, a circular plate with a diameter of 180 mm was punched out. The circular plate was processed by deep drawing using a cup punching machine, followed by two stages of re-drawing and one stage of thinning to form a can with an inner diameter of 52 mm and a can height of 163 mm. For the formed can, the surface of the resin coating layer on the outer surface side of the can was visually observed and the processability was evaluated according to the following criteria. In the following evaluation, "○" was judged as being able to suppress the damage of the resin coating layer accompanying the canning process and was rated as qualified.

[0104] Evaluation "○": No damage to the resin coating layer was observed. No practical problem.

[0105] Evaluation "x": Damage to the resin coating layer or damage to the can body was observed. There are practical problems.

[0106] (2) Scratch resistance

[0107] After coating the container with paraffin on the resin-coated metal plate, a circular plate with a diameter of 180 mm is punched out. The circular plate is processed by deep drawing using a cup punching machine, followed by two stages of re-drawing and one stage of thinning to form a can with an inner diameter of 52 mm and a can height of 163 mm. The formed can is heated from room temperature to 240°C within 2 minutes, and then forced to cool with cold air. For the cooled can, the surface of the resin coating layer on the outer surface of the can is visually observed, and the scratch resistance is evaluated according to the following criteria. In the following evaluation, "◎" and "○" are judged as being able to suppress scratches on the resin coating layer during canning processing and are rated as qualified.

[0108] Evaluation "◎": No scratches were observed.

[0109] Evaluation "○": Scratches occurred within 5 mm from the can flange portion. No practical problem.

[0110] Evaluation "△": Scratches occurred at a height of more than 5 mm and within 20 mm from the can flange portion. There is a practical problem.

[0111] Evaluation "x": Scratches or damage to the can body occurred at a height exceeding 20 mm from the can flange portion. There is a practical problem.

[0112] Evaluation "-": The resin coating layer or the can body was damaged during can manufacturing, and the scratch resistance could not be evaluated. There is a practical problem.

[0113] (3) Printing coating adhesion

[0114] For the resin-coated metal plate for the container, a hot air drying furnace was used to heat treat the plate from room temperature to 240°C within 2 minutes, and then cooled to room temperature. Then, a polyester-based printed coating was printed on the resin coating layer on the outer surface side of the container of each sample, and a hot air drying furnace was used to heat treat the plate from room temperature to 185°C for 90 seconds, and then cooled to room temperature. For the surface of the sample printed with the printed coating, a scratch coating hardness meter was used to scan from the printed end at a speed of 10 mm / min. under a load of 500 g, and the maximum pencil hardness at which the printed coating does not peel off was measured. Based on the pencil hardness, the adhesion of the printed coating was evaluated according to the following criteria. In the following evaluation, "◎" and "○" were judged as having excellent adhesion of the printed coating after canning and were rated as qualified.

[0115] Evaluation "◎": pencil hardness 3H or more.

[0116] Evaluation "○": Pencil hardness 2H. No practical problem.

[0117] Evaluation "△": pencil hardness H. There are practical problems.

[0118] Evaluation "×": Pencil hardness is F or less. There are practical problems.

[0119] Table 5 shows the respective evaluation results.

[0120]

[0121]

[0122]

[0123]

[0124] [Table 5]

[0125] Processability Scratch resistance Printing coating adhesion Example 1 ○ ◎ ◎ Example 2 ○ ◎ ◎ Example 3 ○ ◎ ◎ Example 4 ○ ◎ ◎ Example 5 ○ ◎ ◎ Example 6 ○ ◎ ◎ Example 7 ○ ◎ ◎ Example 8 ○ ◎ ◎ Example 9 ○ ◎ ○ Example 10 ○ ◎ ◎ Embodiment 11 ○ ○ ◎ Example 12 ○ ○ ◎ Embodiment 13 ○ ◎ ◎ Embodiment 14 ○ ◎ ◎ Embodiment 15 ○ ◎ ◎ Example 16 ○ ◎ ◎ Embodiment 17 ○ ○ ◎ Embodiment 18 ○ ○ ◎ Embodiment 19 ○ ◎ ◎ Embodiment 20 ○ ◎ ◎ Embodiment 21 ○ ◎ ◎ Embodiment 22 ○ ◎ ○ Embodiment 23 ○ ○ ◎ Embodiment 24 ○ ◎ ◎ Comparative Example 1 ○ × ◎ Comparative Example 2 × - × Comparative Example 3 × - △ Comparative Example 4 × - △ Comparative Example 5 × - × Comparative Example 6 ○ × ◎ Comparative Example 7 × - × Comparative Example 8 × - △ Comparative Example 9 ○ △ ×

[0126] As shown in Table 5, in each example, the processability (breakage resistance), scratch resistance, and print coating adhesion are all good. In addition, a resin-coated metal sheet for a container that can suppress the breakage and scratching of the resin coating layer accompanying the canning process and has excellent adhesion to the print coating after the canning process is obtained. In contrast, in each comparative example, the evaluation results of any one of the processability, scratch resistance, and print coating adhesion are insufficient.

[0127] Explanation of symbols

[0128] 1.10 Resin-coated metal sheets for containers

[0129] 2 Metal Plate

[0130] 3.30 (Polyester) resin coating

[0131] 4 Resin coating

[0132] 30a The most superficial layer

[0133] 30b Middle layer

[0134] 30c bottom layer

Claims

1. A resin-coated metal sheet for a container, comprising a polyester resin coating layer on at least one surface of the metal sheet, In the polyester resin coating layer, The 1730 cm －1 The half-value width of the peak caused by the C=O stretching vibration nearby is 24 cm －1 ~28cm －1 The laser Raman spectroscopy is performed by making the polarization plane of a linearly polarized laser with a wavelength of 532 nm parallel to the rolling direction of the metal plate incident on the surface of the polyester resin coating layer for measurement. Furthermore, it contains 0.010 mass % to 1.0 mass % of an organic lubricant, and The contact angle of diiodomethane on the surface of the polyester resin coating layer after the heat treatment from room temperature to 240° C. within 2 minutes was 23° to 40°.

2. The resin-coated metal sheet for a container according to claim 1, wherein The polyester resin coating layer contains 30 mass % or less of titanium oxide.

3. A resin-coated metal plate for a container, comprising a polyester resin coating layer on at least one surface of the metal plate, In the polyester resin coating layer, having a structure consisting of at least three layers including a topmost layer, an intermediate layer and a bottommost layer, The 1730 cm －1 The half-value width of the peak caused by the C=O stretching vibration nearby is 24 cm －1 ~28cm －1 The laser Raman spectroscopy is performed by making the polarization plane of a linearly polarized laser with a wavelength of 532 nm parallel to the rolling direction of the metal plate incident on the surface of the outermost layer for measurement. The contact angle of diiodomethane on the surface of the outermost layer after heat treatment from room temperature to 240° C. within 2 minutes was 23° to 40°. The outermost layer contains 0.010 mass % to 1.0 mass % of an organic lubricant, The outermost layer and the lowermost layer each contain 0% to 2.0% by mass of titanium oxide, and the intermediate layer contains 10% to 30% by mass of titanium oxide. The film thickness of the outermost layer and the lowermost layer is 1.0 μm to 5.0 μm respectively, and the film thickness of the intermediate layer is 6.0 μm to 30 μm.

4. The resin-coated metal sheet for a container according to any one of claims 1 to 3, wherein The polyester resin coating layer is composed of a resin material containing 90 mol % or more of ethylene terephthalate units.

5. The resin-coated metal sheet for a container according to any one of claims 1 to 4, wherein The organic lubricant comprises an acid-modified polyolefin or an oxidized polyolefin having an acid value of 1.0 mgKOH / g to 100 mgKOH / g.

6. A method for producing a resin-coated metal sheet for a container, which is the method for producing a resin-coated metal sheet for a container according to claim 1 or 2, A polyester resin coating layer containing 0.010 mass % to 1.0 mass % of an organic lubricant is pressed onto a metal plate, and then The surface of the polyester resin coating layer is maintained at a temperature not lower than the melting start temperature of the polyester resin coating layer for 0.50 seconds or more, and then cooled at a cooling rate of 150° C. / second or more.

7. The method for producing a resin-coated metal sheet for a container according to claim 6, wherein: The polyester resin coating layer contains 30 mass % or less of titanium oxide.

8. A method for producing a resin-coated metal sheet for a container, which is the method for producing a resin-coated metal sheet for a container according to claim 3, A polyester resin coating layer is crimped onto a metal plate, the polyester resin coating layer having a structure consisting of at least three layers including an outermost layer, an intermediate layer, and a lowermost layer, the outermost layer containing 0.010 mass % to 1.0 mass % of an organic lubricant, the outermost layer and the lowermost layer each containing 0 mass % to 2.0 mass % of titanium oxide, the intermediate layer containing 10 mass % to 30 mass % of titanium oxide, and then, After the surface of the outermost surface layer is maintained at a temperature higher than the melting start temperature of the outermost surface layer for 0.50 seconds or longer, it is cooled at a cooling rate of 150° C. / second or higher.

9. The method for producing a resin-coated metal sheet for a container according to any one of claims 6 to 8, wherein: The polyester resin coating layer is composed of a resin material containing 90 mol % or more of ethylene terephthalate units.

10. The method for producing a resin-coated metal sheet for a container according to any one of claims 6 to 9, wherein: The organic lubricant comprises an acid-modified polyolefin or an oxidized polyolefin having an acid value of 1.0 mgKOH / g to 100 mgKOH / g.

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